scholarly journals Temperate Air Breathing Increases Cycling Performance in Hot and Humid Climate Environment

Life ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 911
Author(s):  
Clovis Chabert ◽  
Aurélie Collado ◽  
Olivier Hue
Keyword(s):  
Air Temperature ◽  
Cycling Performance ◽  
Humid Climate ◽  
Constant Intensity ◽  
Male Athletes ◽  
Perceived Effort ◽  
Sports Events ◽  
Hot Air ◽  
Air Temperatures ◽  
Hot And Humid Climate

Practicing physical activity in a hot and humid climate (HHC) is becoming increasingly common due to anthropogenic climate change and the growing number of international sports events held in warm countries. The aim of this study was to understand the physiological and psychological effects of breathing two air temperatures during cycling exercise in HHC. Ten male athletes performed two sessions of exercise in HHC (T°: 32.0 ± 0.5 °C, relative humidity: 78.6 ± 0.7%) during which they breathed hot air (HA, 33.2 ± 0.06 °C) or temperate air (TA, 22.6 ± 0.1 °C). Each session was composed of 30 min of pre-fatigue cycling at constant intensity, followed by a 10 min self-regulated performance. During pre-fatigue, TA induced a better feeling score and a lower rating of perceived effort (respectively, +0.9 ± 0.2, p < 0.05; 1.13 ± 0.21; p < 0.05) with no changes in physiological parameters. During performance, oxygen consumption and mechanical workload were increased by TA (respectively, +0.23 ± 0.1 L min−1, p < 0.05 and +19.2 ± 6.1 W, p < 0.01), whereas no significant differences were observed for psychological parameters. Reducing the breathed air temperature decreased the discomfort induced by HHC during exercise and increased the performance capacity during self-regulated exercise. Thus, breathed air temperature perception is linked to the hardship of training sessions and directly contributes to the performance decrease in HHC.

scholarly journals Performance of low-pressure fans operating with hot air

2016 ◽  
Vol 20 (suppl. 5) ◽  
pp. 1435-1447
Author(s):  
Jasmina Bogdanovic-Jovanovic ◽  
Dragica Milenkovic ◽  
Zivan Spasic ◽  
Dragan Svrkota
Keyword(s):  
Air Temperature ◽  
Axial Flow ◽  
Low Pressure ◽  
Operating Conditions ◽  
Empirical Formulas ◽  
Hot Air ◽  
Air Temperatures ◽  
The Common ◽  
Law Of Similarity ◽  
Temperature And Pressure

Performance characteristics of fans are generally provided for the normal temperature and pressure conditions (tI = 20?C, pI = 101.325 kPa, ? I = 1.2 kg/m3). Very often, fans operate in different air conditions, occasionally at different air temperatures. In these cases, equations obtained by the law of similarity are usually used for recalculation of the fan operating parameters. Increasing the inlet air temperature causes a decrease in the characteristic of Reynolds number, and may lead to efficiency lowering of the fan. There are also some empirical formulas for recalculation of fan efficiency, when operating at different air temperatures. In this paper, the common way for obtaining fan performance for different operating conditions (air temperature changing) is presented. The results, obtained by recalculation of fan parameters using a law of similarity, are compared to numerical simulation results of the axial-flow fan operating with different air temperatures. These results are compared with results obtained by some recommended empirical formulas, as well. This paperwork is limited to low-pressure and mid-pressure fans, which represents the majority of all fans used in practice, for different purposes.

scholarly journals 135 Energy Balance and Water Loss of Two Shade Tree Species over Asphalt and Turf in Contrasting Climates

HortScience ◽  
2000 ◽  
Vol 35 (3) ◽  
pp. 412E-413
Author(s):  
Roger Kjelgren ◽  
Janet Cole
Keyword(s):  
Stomatal Conductance ◽  
Vapor Pressure ◽  
Air Temperature ◽  
Water Loss ◽  
Stomatal Closure ◽  
Longwave Radiation ◽  
Humid Climate ◽  
Silver Maple ◽  
Air Temperatures ◽  
Temperature Surface

We investigated water loss of shade trees over turf and asphalt in an arid and humid climate for Russian olive and silver maple. Total daily tree water loss, and dawn-to-dusk stomatal conductance (gs) and leaf temperature (Tl), as well as air temperature, surface temperature, and vapor pressure deficit, were measured in Logan, Utah, and Stillwater, Okla., in early and mid-summer. Midday air temperatures in mid-summer were similar at both locations, 30 to 35 °C. Comparable vapor pressure deficits (VPD, kPa) were much higher in Logan, 3.5–5.0, than Stillwater, 2–2.5. Differences in humidity and air temperature between asphalt and turf were negligible at both Stillwater and Logan. Midday surface temperatures for asphalt and turf averaged 34 and 50 °C, respectively, in Logan, but were 10 °C higher for both surfaces in Oklahoma. The effect of higher longwave radiation from hotter surfaces on stomatal conductance and water loss of trees over asphalt in Stillwater was not consistently different for either species from those over turf. However, at Logan, Tl of trees over asphalt were consistently 2 to 4 °C higher and gs was 10% to 20% lower than those over turf. Stomatal closure for trees over asphalt resulted in water loss that was the same or slightly lower as trees over turf. The effect of paved surfaces on tree water loss appears to be more pronounced in an arid than a humid climate. The combined effect of higher VPD in an arid region and greater longwave radiation from hotter paved surfaces induces stomatal closure that limits water loss, and likely photosynthesis. By contrast, in humid regions, increased tree radiation interception over asphalt does not appear to trigger stomatal closure due to lower VPD.

Flame Propagation Following the Autoignition of Axisymmetric Hydrogen, Acetylene, and Normal-Heptane Plumes in Turbulent Coflows of Hot Air

2007 ◽  
Vol 130 (1) ◽  
Author(s):  
Christos N. Markides ◽  
Epaminondas Mastorakos
Keyword(s):  
Flame Propagation ◽  
Air Temperature ◽  
High Speed ◽  
High Speed Camera ◽  
Stoichiometric Mixture ◽  
Air Velocity ◽  
Flame Propagation Velocity ◽  
Hot Air ◽  
Air Temperatures ◽  
Continuous Injection

Axisymmetric plumes of hydrogen, acetylene, or n-heptane were formed by the continuous injection of (pure or nitrogen-diluted) fuel into confined turbulent coflows of hot air. Autoignition and subsequent flame propagation was visualized with an intensified high-speed camera. The resulting phenomena that were observed include the statistically steady “random spots” regime and the “flashback” regime. It was found that with higher velocities and smaller injector diameters, the boundary between random spots and flashback shifted to higher air temperatures. In the random spots regime the autoignition regions moved closer to the injector with increasing air temperature and/or decreasing air velocity. After a localized explosive autoignition event, flames propagated into the unburnt mixture in all directions and eventually extinguished, giving rise to autoignition spots of mean radii of 2–5mm for hydrogen and 6–10mm for the hydrocarbons. The average flame propagation velocity in both the axial and radial directions varied between 0.5 and 1.2 times the laminar burning speed of the stoichiometric mixture, increasing as the autoigniting regions shifted upstream.

Influence of Water Bodies on Outdoor Air Temperature in Hot and Humid Climate

ICSDC 2011 ◽  
2012 ◽  
Author(s):  
Nyuk Hien Wong ◽  
Chun Liang Tan ◽  
Andrita Dyah Shinta Nindyani ◽  
Steve Kardinal Jusuf ◽  
Erna Tan
Keyword(s):  
Air Temperature ◽  
Water Bodies ◽  
Outdoor Air ◽  
Humid Climate ◽  
Influence Of Water ◽  
Hot And Humid Climate

scholarly journals Thermal performance of a non–segmented and segmented tall atrium in hot and humid climate

2021 ◽  
Vol 2042 (1) ◽  
pp. 012162
Author(s):  
Priya Pawar ◽  
Deying Zhang ◽  
Xiaoying Wu ◽  
Werner Lang
Keyword(s):  
Wind Velocity ◽  
Air Temperature ◽  
Indoor Air ◽  
Thermal Conditions ◽  
Wind Pressure ◽  
Humid Climate ◽  
Pressure Coefficients ◽  
Starting Point ◽  
Buoyancy Forces ◽  
Hot And Humid Climate

Abstract The study was designed to quantify the thermal conditions in tall atria in office buildings to serve as a starting point towards understanding their performance. The simulation study of a non-segmented and segmented atrium of 250 m height reveals indoor air temperature, wind velocity contours and wind pressure coefficients at various heights of each atrium type. In a hot and humid climate like that of Singapore, the internal temperatures within each atrium stack remain constant at 27°C. However, the wind velocity in the non-segmented atrium (of 0.5 - 0.7 m/s) is lower than acceptable (0.9 m/s) for human occupancy. Adding segments and a larger inlet to the atrium solves the problem of low wind velocity without increasing the effective ambient temperature within the atrium stack. Additionally, the segmented atrium offers the advantage of displaying lower buoyancy forces by lowering the pressure differential within a tall stack thereby providing better comfort conditions.

Influence of Glazing Types on the Indoor Thermal Performance of Tropical High-Rise Residential Buildings

2016 ◽  
Vol 692 ◽  
pp. 27-37
Author(s):  
Nedhal Al-Tamimi ◽  
Abdultawab Qahtan
Keyword(s):  
Air Temperature ◽  
Indoor Air ◽  
Residential Buildings ◽  
Primary Objective ◽  
Radiation Absorption ◽  
Base Case ◽  
Indoor Environments ◽  
Humid Climate ◽  
High Rise ◽  
Hot And Humid Climate

In tropical climates, the solar radiation absorption of glazed windows results in overheated indoor environments and increased cooling energy loads during daytime. Meanwhile, situations differ during nighttime. The present study focuses on the effects of glazing type on the indoor temperature in high-rise residential buildings in the hot and humid climate of Malaysia. The primary objective of this study is to assess the effects of six glazing types on the indoor air temperature of the base case room oriented toward the southwest with a Window Wall Ratio WWR of 45% under both ventilated and unventilated conditions. The effects during daytime and nighttime are investigated separately. A computerized simulation tool (Virtual Environment by Integrated Environmental Solutions) is used to conduct the investigation. Penang is selected as the empirical background location of a hot and humid climate. The study found that reflective double glazing exhibits lower indoor air temperature throughout the day regardless of the ventilation condition, with an optimum improvement of up to 107% and 14% in unventilated and ventilated rooms, respectively, compared with single clear glazing. The study recommends the use of reflective single or double glass in regions with a hot and humid climate similar to that of Malaysia.

Flame Propagation Following the Autoignition of Axisymmetric Hydrogen, Acetylene and Normal-Heptane Plumes in Turbulent Co-Flows of Hot Air

2006 ◽  
Author(s):  
Christos N. Markides ◽  
Epaminondas Mastorakos
Keyword(s):  
Flame Propagation ◽  
Air Temperature ◽  
High Speed ◽  
Stoichiometric Mixture ◽  
Air Velocity ◽  
Flame Propagation Velocity ◽  
Hot Air ◽  
Air Temperatures ◽  
Intensified Camera ◽  
Continuous Injection

Axisymmetric plumes of hydrogen, acetylene or n-heptane were formed by the continuous injection of (pure or nitrogen-diluted) fuel into turbulent co-flows of hot air. Autoignition and subsequent flame propagation was visualized with a high-speed intensified camera. The resulting phenomena include the statistically steady ‘Random Spots’ and the ‘Flashback’ regimes. It was found that with higher velocities and smaller injector diameters, the boundary between Flashback and Random Spots shifted to higher air temperatures. In the Random Spots regime, the autoignition regions moved closer to the injector with increasing air temperature and/or decreasing air velocity. After a localized explosive autoignition event, flames propagated into the unburnt mixture in all directions and eventually extinguished, giving rise to autoignition ‘spots’ of mean radius 2–5mm for hydrogen and 6–10mm for the hydrocarbons. The average flame propagation velocity in both the axial and radial directions varied between 0.5 and 1.2 times the laminar burning speed of the stoichiometric mixture, increasing as the autoigniting regions shifted upstream.

On the dynamics of distribution of the American White Butterfly, Hyphantria cunea Drury, 1973 (Lepidoptera, Arctiidae), in Ukraine regarding the annual minimal air temperatures

2018 ◽  
Vol 14 (1) ◽  
pp. 44-57
Author(s):  
S. N. Shumov
Keyword(s):  
Air Temperature ◽  
Annual Reports ◽  
Complete Elimination ◽  
Hyphantria Cunea ◽  
White American ◽  
Gis Technologies ◽  
Data Analyses ◽  
Air Temperatures ◽  
Negative Temperatures

The spatial analysis of distribution and quantity of Hyphantria cunea Drury, 1973 across Ukraine since 1952 till 2016 regarding the values of annual absolute temperatures of ground air is performed using the Gis-technologies. The long-term pest dissemination data (Annual reports…, 1951–1985; Surveys of the distribution of quarantine pests ..., 1986–2017) and meteorological information (Meteorological Yearbooks of air temperature the surface layer of the atmosphere in Ukraine for the period 1951-2016; Branch State of the Hydrometeorological Service at the Central Geophysical Observatory of the Ministry for Emergencies) were used in the present research. The values of boundary negative temperatures of winter diapause of Hyphantria cunea, that unable the development of species’ subsequent generation, are received. Data analyses suggests almost complete elimination of winter diapausing individuals of White American Butterfly (especially pupae) under the air temperature of −32°С. Because of arising questions on the time of action of absolute minimal air temperatures, it is necessary to ascertain the boundary negative temperatures of winter diapause for White American Butterfly. It is also necessary to perform the more detailed research of a corresponding biological material with application to the freezing technics, giving temperature up to −50°С, with the subsequent analysis of the received results by the punched-analysis.

scholarly journals Heatwaves and Summer Urban Heat Islands: A Daily Cycle Approach to Unveil the Urban Thermal Signal Changes in Lisbon, Portugal

Atmosphere ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 292 ◽  
Author(s):  
Ana Oliveira ◽  
António Lopes ◽  
Ezequiel Correia ◽  
Samuel Niza ◽  
Amílcar Soares
Keyword(s):  
Climate Change ◽  
Air Temperature ◽  
Wind Direction ◽  
Urban Heat Islands ◽  
Daily Cycle ◽  
Local Climate ◽  
Thermal Signal ◽  
Air Temperatures ◽  
Local Climate Change ◽  
Urban Heat

Lisbon is a European Mediterranean city, greatly exposed to heatwaves (HW), according to recent trends and climate change prospects. Considering the Atlantic influence, air temperature observations from Lisbon’s mesoscale network are used to investigate the interactions between background weather and the urban thermal signal (UTS) in summer. Days are classified according to the prevailing regional wind direction, and hourly UTS is compared between HW and non-HW conditions. Northern-wind days predominate, revealing greater maximum air temperatures (up to 40 °C) and greater thermal amplitudes (approximately 10 °C), and account for 37 out of 49 HW days; southern-wind days have milder temperatures, and no HWs occur. Results show that the wind direction groups are significantly different. While southern-wind days have minor UTS variations, northern-wind days have a consistent UTS daily cycle: a diurnal urban cooling island (UCI) (often lower than –1.0 °C), a late afternoon peak urban heat island (UHI) (occasionally surpassing 4.0 °C), and a stable nocturnal UHI (1.5 °C median intensity). UHI/UCI intensities are not significantly different between HW and non-HW conditions, although the synoptic influence is noted. Results indicate that, in Lisbon, the UHI intensity does not increase during HW events, although it is significantly affected by wind. As such, local climate change adaptation strategies must be based on scenarios that account for the synergies between potential changes in regional air temperature and wind.

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