Welding with a heated tool in the tube of plastic pipes at low ambient air temperatures

2021 ◽  
pp. 54-58
Author(s):  
S.P. Starostin ◽  
O.A. Ammosova ◽  
M.A. Vasilyeva ◽  
E.V. Danzanova
Keyword(s):  
Ambient Air ◽  
Plastic Pipes ◽  
Air Temperatures

Physical fitness and thermoregulatory reactions in a cold environment in men

1988 ◽  
Vol 65 (5) ◽  
pp. 1984-1989 ◽  
Author(s):  
J. H. Bittel ◽  
C. Nonotte-Varly ◽  
G. H. Livecchi-Gonnot ◽  
G. L. Savourey ◽  
A. M. Hanniquet
Keyword(s):  
Physical Fitness ◽  
Cold Stress ◽  
Heat Production ◽  
Ambient Air ◽  
Metabolic Heat Production ◽  
Adult Males ◽  
Fitness Level ◽  
Metabolic Heat ◽  
Air Temperatures ◽  
Thermoregulatory Reactions

The relationship between the physical fitness level (maximal O2 consumption, VO2max) and thermoregulatory reactions was studied in 17 adult males submitted to an acute cold exposure. Standard cold tests were performed in nude subjects, lying for 2 h in a climatic chamber at three ambient air temperatures (10, 5, and 1 degrees C). The level of physical fitness conditioned the intensity of thermoregulatory reactions to cold. For all subjects, there was a direct relationship between physical fitness and 1) metabolic heat production, 2) level of mean skin temperature (Tsk), 3) level of skin conductance, and 4) level of Tsk at the onset of shivering. The predominance of thermogenic or insulative reactions depended on the intensity of the cold stress: insulative reactions were preferential at 10 degrees C, or even at 5 degrees C, whereas colder ambient temperature (1 degree C) triggered metabolic heat production abilities, which were closely related to the subject's physical fitness level. Fit subjects have more efficient thermoregulatory abilities against cold stress than unfit subjects, certainly because of an improved sensitivity of the thermoregulatory system.

scholarly journals Direct Calculation of Thermodynamic Wet-Bulb Temperature as a Function of Pressure and Elevation

2013 ◽  
Vol 30 (8) ◽  
pp. 1757-1765 ◽  
Author(s):  
Sayed-Hossein Sadeghi ◽  
Troy R. Peters ◽  
Douglas R. Cobos ◽  
Henry W. Loescher ◽  
Colin S. Campbell
Keyword(s):  
Air Temperature ◽  
Mean Absolute Error ◽  
Direct Calculation ◽  
Ambient Air ◽  
Absolute Error ◽  
Mean Square ◽  
Air Temperatures ◽  
Order Polynomial ◽  
The Mean ◽  
Very High

Abstract A simple analytical method was developed for directly calculating the thermodynamic wet-bulb temperature from air temperature and the vapor pressure (or relative humidity) at elevations up to 4500 m above MSL was developed. This methodology was based on the fact that the wet-bulb temperature can be closely approximated by a second-order polynomial in both the positive and negative ranges in ambient air temperature. The method in this study builds upon this understanding and provides results for the negative range of air temperatures (−17° to 0°C), so that the maximum observed error in this area is equal to or smaller than −0.17°C. For temperatures ≥0°C, wet-bulb temperature accuracy was ±0.65°C, and larger errors corresponded to very high temperatures (Ta ≥ 39°C) and/or very high or low relative humidities (5% < RH < 10% or RH > 98%). The mean absolute error and the root-mean-square error were 0.15° and 0.2°C, respectively.

scholarly journals Measurement report: Chemical characteristics of PM<sub>2.5</sub> during typical biomass burning season at an agricultural site of the North China Plain

2021 ◽  
Vol 21 (4) ◽  
pp. 3181-3192
Author(s):  
Linlin Liang ◽  
Guenter Engling ◽  
Chang Liu ◽  
Wanyun Xu ◽  
Xuyan Liu ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Inorganic Ions ◽  
Northern China ◽  
Ambient Air ◽  
Rural Site ◽  
Biomass Combustion ◽  
Chemical Components ◽  
The North ◽  
Air Temperatures ◽  
Agricultural Site

Abstract. Biomass burning activities are ubiquitous in China, especially in northern China, where there is a large rural population and winter heating custom. Biomass burning tracers (i.e., levoglucosan, mannosan and potassium (K+)), as well as other chemical components, were quantified at a rural site (Gucheng, GC) in northern China from 15 October to 30 November, during a transition heating season, when the field burning of agricultural residue was becoming intense. The measured daily average concentrations of levoglucosan, mannosan and K+ in PM2.5 (particulate matter with aerodynamic diameters less than 2.5 µm) during this study were 0.79 ± 0.75, 0.03 ± 0.03 and 1.52 ± 0.62 µg m−3, respectively. Carbonaceous components and biomass burning tracers showed higher levels during nighttime than daytime, while secondary inorganic ions were enhanced during daytime. An episode with high levels of biomass burning tracers was encountered at the end of October 2016, with high levoglucosan at 4.37 µg m−3. Based on the comparison of chemical components during different biomass burning pollution periods, it appeared that biomass combustion can obviously elevate carbonaceous component levels, whereas there was essentially no effect on secondary inorganic aerosols in the ambient air. Moreover, the levoglucosan / mannosan ratios during different biomass burning pollution periods remained at high values (in the range of 18.3–24.9); however, the levoglucosan / K+ ratio was significantly elevated during the intensive biomass burning pollution period (1.67) when air temperatures were decreasing, which was substantially higher than in other biomass burning periods (averaged at 0.47).

Nasal heat and water exchange in gray seals

1987 ◽  
Vol 253 (6) ◽  
pp. R883-R889 ◽  
Author(s):  
L. P. Folkow ◽  
A. S. Blix
Keyword(s):  
Water Exchange ◽  
Ambient Air ◽  
Minute Volume ◽  
Halichoerus Grypus ◽  
Evaporative Water ◽  
Air Temperatures ◽  
Respiratory Heat Loss ◽  
Average Maximum ◽  
Lower Critical Temperature ◽  
Gray Seals

Metabolic rate (MR), expired air temperature (Tex), respiratory frequency (f), respiratory minute volume (V), and skin (Ts) and body (Tb) temperatures were recorded in three gray seals (Halichoerus grypus) at ambient air temperatures (Ta) between -40 and +20 degrees C. At Ta within the thermoneutral zone, MR averaged 3.7 W.kg-0.75, while mean V was 0.26 1.min-1.kg-0.75. At Ta below -11 degrees C [apparent lower critical temperature (Tlc)], both MR and V increased linearly with decreasing Ta. Average maximum MR (9.6 W.kg-0.75) and V (0.57 1.min-1.kg-0.75) were both recorded at Ta of -40 degrees C. Tex decreased with decreasing Ta to an average minimum value of 8 degrees C at Ta of -30 degrees C. The highest Tex recorded was 32 degrees C at Ta of +20 degrees C. At Ta of -20 degrees C, both total respiratory heat loss, with one exception, and respiratory evaporative water loss reached their lowest values. At this Ta, 66% of the heat and 80% of the water added to the inspired air were regained on expiration. We suggest that nasal heat exchange may be of considerable importance for thermal and water balance in many pinnipeds.

Effect of temperature on transcapillary water movement in isolated cat hindlimb

1985 ◽  
Vol 249 (4) ◽  
pp. H792-H798
Author(s):  
M. B. Wolf ◽  
P. D. Watson
Keyword(s):  
Low Temperature ◽  
Water Movement ◽  
Control Period ◽  
Ambient Air ◽  
Tissue Temperature ◽  
Thigh Muscle ◽  
Effect Of Temperature ◽  
Air Temperatures ◽  
Initial Control ◽  
Water Viscosity

Capillary filtration coefficient (CFC) was measured in the isolated cat hindlimb preparation, perfused at 20 ml X min-1 X 100 g muscle-1 with a perfusate containing 6 g/dl albumin and normal electrolyte concentrations, to which were added 50 ml of the cat's blood and 6 micrograms of the vasodilator isoproterenol. CFC was determined three to six times in an initial control period during which the tissue temperature (measured by a 5-mm disk thermistor implanted in a thigh muscle) was controlled near 37 degrees C. Tissue temperature was decreased to 5-10 degrees C by lowering perfusate and ambient air temperatures. About 50 min were required for tissue temperature equilibration. CFC was measured at low temperature and then again at 37 degrees C. For nine experiments, the ratio of CFC at low temperature to that in the 37 degrees C control periods averaged 87% of the ratio of water viscosity at 37 degrees C to that at low temperature. The activation energy for water calculated from these data was 5.0 kcal/mol. These results may be explained by all transcapillary water flow moving by diffusion through narrow pores or by about 90% moving by convection, with the remainder going through a lipid pathway. However, the results may be entirely due to a direct effect of temperature on the geometry of the transcapillary pathway for water movement.

EFFECTS OF LOW FLUCTUATING TEMPERATURES ON FARM ANIMALS: I. INFLUENCE OF AMBIENT AIR TEMPERATURE ON THE RESPIRATION RATE, HEART RATE, AND RECTAL TEMPERATURE OF LACTATING HOLSTEIN-FRIESIAN COWS

1958 ◽  
Vol 38 (1) ◽  
pp. 10-22 ◽  
Author(s):  
M. A. MacDonald ◽  
J. M. Bell
Keyword(s):  
Heart Rate ◽  
Respiration Rate ◽  
Air Temperature ◽  
Rectal Temperature ◽  
Ambient Air ◽  
Farm Animals ◽  
Measurement Unit ◽  
Ambient Air Temperature ◽  
Air Temperatures ◽  
Holstein Friesian

This report presents data on the effect of low fluctuating ambient air temperatures on the rectal temperature, heart rate, and respiration rate in lactating Holstein-Friesian cows.Daily minimum ambient air temperature (DMAAT) inside the uninsulated University of Saskatchewan loose-housing shed ranged from −5° F. to 38° F. As ambient temperature decreased, rectal temperature and heart rate increased, while respiration rate decreased. Levels of significance were 10, 9, and 1 per cent for regressions of rectal temperature, heart rate, and respiration rate, respectively, on DMAAT. Levels of significance were 7, 10, and 1 per cent for regressions of rectal temperature, heart rate, and respiration rate, respectively, on degree hours per day (d-h/day). Degree hours per day is a measurement unit developed by the authors and is based on time and difference in degrees from 50° F.Change in rectal temperature and heart rate were not significantly (P = >.05) correlated with either change in d-h/day or change in DMAAT. Change in respiration rate was significantly (P = <.02) and negatively correlated with change in d-h/day and significantly (P = <.06) and positively correlated with change in DMAAT.Heart rate, rectal temperature, and respiration rate were not significantly correlated with each other. However, change in respiration rate was positively correlated with change in rectal temperature (P = <.03).While the influence of low temperatures resulted in small changes in these physiological characteristics compared to those experienced elsewhere in high temperature zones, it cannot be concluded that lactating cows were entirely free of thermal stress at temperatures as low as 0° F.

scholarly journals Energetic investigation of energy recovery technologies in air handling units

2018 ◽  
Vol 9 (1) ◽  
pp. 49-57
Author(s):  
L. F. Al-Hyari ◽  
M. Kassai
Keyword(s):  
Energy Consumption ◽  
Indoor Air ◽  
Energy Recovery ◽  
Ventilation System ◽  
Ambient Air ◽  
Existing Buildings ◽  
Exact Methods ◽  
Technical Data ◽  
Air Temperatures ◽  
Air Handling Units

The statistical data show that the application of active cooling is spread widely in residential and commercial buildings. In these buildings, the ventilation is significantly increased in the whole energy consumption. There are similar problems in the operation of post-insulation of existing buildings. In this case, the energy consumption of the ventilation system gives a major proportion of the whole building services energy consumption. The opportuneness of this research shows that the actual available calculation procedures and technical designing data are only rough approximations for analyzing the energy consumption of air handling units and the energy saved by the integrated heat or energy recovery units. There are not exact methods and unequivocal technical data. In previous researches, the production and development companies have not investigated the effectiveness of the energy recovery units under difference ambient air conditions and the period of defrost cycle when the heat recovery can only partly operate under difference ambient air temperatures. During this term, a re-heater has to fully heat up the ambient cold air to the temperature of supplied air and generate the required heating demand to provide the necessary indoor air temperature.

scholarly journals Frost Resilience of Stabilized Earth Building Materials

Geosciences ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 328 ◽  
Author(s):  
Alan W. Rempel ◽  
Alexandra R. Rempel
Keyword(s):  
Building Materials ◽  
Thermal Stresses ◽  
Fiber Type ◽  
Damage Index ◽  
Material Design ◽  
Ambient Air ◽  
Frost Damage ◽  
Embodied Energy ◽  
Surface Erosion ◽  
Air Temperatures

Earth-based building materials are increasingly valued in green design for their low embodied energy, humidity-buffering ability, and thermal stability. These materials perform well in warm dry climates, but greater understanding of long-term durability is needed for successful adoption in colder and/or wetter climates. The presence of stabilizers dramatically improves resistance to surface erosion from wind and rain, compared to unstabilized adobe and cob counterparts, and the influences of soil composition, fiber type, and diverse binders, on rain and wind surface erosion have been investigated in detail. Frost and freeze-thaw resistance, however, have been less well-studied, despite strong interest in stabilized earth materials in northern North America, Europe, and Asia. In particular, recent studies have relied on a widespread misunderstanding of the mechanism by which frost damage occurs in porous materials that will impede efforts to create valid models for material design and improvement. In addition, the influence of radiative thermal stresses on wall surfaces has been overlooked in favor of focus on ambient air temperatures. Here, we apply contemporary understanding of cracking by segregated ice growth to develop a macroscopic damage index that enables comparison between performance of different materials subject to different weather patterns. An examination of predicted damage patterns for two stabilized earth building materials and two conventional materials in twelve cities over two time periods reveals the dominant factors that govern frost vulnerability. We find that the frost resilience of earth building materials is comparable to that of the conventional materials we examined, and that assessments that neglect expected variations in water content by assuming full saturation are likely to yield misleading results. Over recent years, increased winter temperatures in several cities we examined predict reduced material vulnerability to frost damage, but we also find that accompanying increases in humidity levels have made some cities much more vulnerable.

scholarly journals Photosynthetic performance of rock-colonising lichens in the Mountain Zebra National Park, South Africa

Koedoe ◽  
1993 ◽  
Vol 36 (1) ◽  
Author(s):  
Dirk Wessels ◽  
Ludger Kappen
Keyword(s):  
South Africa ◽  
Volcanic Rock ◽  
National Park ◽  
Ambient Air ◽  
Early Morning ◽  
Photosynthetic Performance ◽  
The Other ◽  
Air Temperatures ◽  
Desert Regions

The photosynthetic behaviour of endolithic andepilithic lichens characteristic of sedimentary and volcanic rock was investigated in situ in the Mountain Zebra National Park, South Africa. The park forms part of an inland semi-desert known as the Karoo, in the Cape Province. Temperatures within Balfour sandstone were monitored, the results showing that during the early morning, temperatures within the sandstone were nearly 5@C lower than ambient air temperatures. This may enhance the frequency of water condensing on the sandstone, which may be particularly important for the endoliths Leciclea aff. sarcogynoides and Sarcogyne cf. austroafricana. Maximum photosynthetic rates of the investigated species were found at temperatures between 20@C and 30@C, far higher than the recorded optimum temperatures for lichens from temperate and desert regions. Parmelia chlorea was the most productive species. Compared to the other epiliths, Peltula capensis was found to be a moderately productive species. The photosynthetic gain of Leciclea aff. sarcogynoides and Sarcogyne cf. austro-africana was low, but the photosynthetic gain of these two species still exceeded that of Acarospora sp.

scholarly journals Tree-hugging koalas demonstrate a novel thermoregulatory mechanism for arboreal mammals

2014 ◽  
Vol 10 (6) ◽  
pp. 20140235 ◽  
Author(s):  
Natalie J. Briscoe ◽  
Kathrine A. Handasyde ◽  
Stephen R. Griffiths ◽  
Warren P. Porter ◽  
Andrew Krockenberger ◽  
...  
Keyword(s):  
Ambient Air ◽  
Climate Impacts ◽  
Heat Sinks ◽  
Biophysical Model ◽  
Conductive Heat ◽  
Phascolarctos Cinereus ◽  
Extreme Heat Events ◽  
Air Temperatures ◽  
Hot Weather

How climate impacts organisms depends not only on their physiology, but also whether they can buffer themselves against climate variability via their behaviour. One of the way species can withstand hot temperatures is by seeking out cool microclimates, but only if their habitat provides such refugia. Here, we describe a novel thermoregulatory strategy in an arboreal mammal, the koala Phascolarctos cinereus. During hot weather, koalas enhanced conductive heat loss by seeking out and resting against tree trunks that were substantially cooler than ambient air temperature. Using a biophysical model of heat exchange, we show that this behaviour greatly reduces the amount of heat that must be lost via evaporative cooling, potentially increasing koala survival during extreme heat events. While it has long been known that internal temperatures of trees differ from ambient air temperatures, the relevance of this for arboreal and semi-arboreal mammals has not previously been explored. Our results highlight the important role of tree trunks as aboveground ‘heat sinks’, providing cool local microenvironments not only for koalas, but also for all tree-dwelling species.

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