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Temperature Drop (temperature + drop)
Selected AbstractsDecadal-scale changes in the tails of probability distribution functions of climate variables in SwitzerlandINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 10 2009Martin Beniston Abstract An analysis of several Swiss climatological sites reveals that a substantial change in the behaviour of pressure, minimum and maximum temperature extremes has occurred in the past two decades. Extreme cold tails defined by the 10% quantiles of temperature drop by a factor of 2 or 3, while the upper tails (beyond the 90% quantile) exhibit a four- or five-fold increase in all seasons. Pressure shows contrasting behaviour, with increases in wintertime highs and summertime lows, while precipitation shows little change. On the basis of the observed datasets, temperature biases related to extremes of pressure or precipitation have been computed, as well as for joint combinations of precipitation and pressure extremes. The most dominant bias is associated with periods without rainfall, during which temperatures are at least 1 °C warmer than otherwise. Changes in the behaviour of joint combinations of extreme pressure and precipitation regimes also have a discernible influence on temperatures. Copyright © 2008 Royal Meteorological Society [source] Experimental analysis of capillary tubes behaviour with some HCFC-22 alternative refrigerantsINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 14 2001Samuel M. Sami Abstract In this paper, an experimental study is presented to enhance our understanding of the capillary tube behaviour using some new alternative refrigerants to HCFC-22. An experimental setup fully instrumented was used to gather the behaviour of three different capillary tube geometries with R-410B, R-407C, and R-410A under various conditions; saturated, sub-cooled and two-phase. Experimental data showed that R-410B has the highest pressure drop along the capillary tubes compared to the alternatives under question and also has the highest temperature drop along the capillary tube. The data also showed that R-407C has similar capillary behaviour to that of R-22. The results clearly demonstrated that the pressure drop is significantly influenced by the diameter of the capillary tube, the type of refrigerant and inlet conditions to the capillary tube. The data also showed that the capillary pressure drop decreases with the increase of the capillary diameter. There is clear evidence that the component concentration of the refrigerant mixture significantly affects the capillary tube behaviour and particularly the pressure drop along the capillary tube length. Copyright © 2001 John Wiley & Sons, Ltd. [source] The effect of heat and moisture exchanger on humidity and body temperature in a low-flow anaesthesia systemACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 5 2003A. Johansson Background: Artificial humidification of dry inspired gases seems to reduce the drop in body temperature during surgery. The aim of this study was to evaluate the humidity and temperature of anaesthetic gases with heat and moisture exchangers (HMEs). The secondary aim was to evaluate if HMEs in combination with low-flow anaesthesia could prevent a decrease in the body temperature during general anaesthesia. Methods: Ninety patients scheduled for general surgery were randomised to receive a fresh gas flow of 1.0, 3.0 or 6.0 l min,1 with or without HMEs in a circle anaesthesia system. Relative humidity, absolute humidity, temperature of inspired gases and body temperatures were measured during 120 min of anaesthesia. Results: The inspiratory absolute humidity levels with HMEs were 32.7 ± 3.1, 32.1 ± 1.1 and 29.2 ± 1.9 mg H2O l,1 and 26.6 ± 2.3, 22.6 ± 3.0 and 13.0 ± 2.6 mg H2O l,1 without HMEs after 120 min of anaesthesia with 1.0, 3.0, or 6.0 l min,1 fresh gas flows (P < 0.05, between with and without HME). The relative humidity levels with HMEs were 93.8 ± 3.3, 92.7 ± 2.2 and 90.7 ± 3.5%, and without the HMEs 95.2 ± 4.5, 86.8 ± 8.0 and 52.8 ± 9.8% (P < 0.05, between with and without HMEs in the 3.0 and 6.0 l min,1 groups). The inspiratory gas temperatures with HMEs were 32.5 ± 2.0, 32.4 ± 0.5 and 31.0 ± 1.9°C, and 28.4 ± 1.5, 27.1 ± 0.8 and 26.1 ± 0.6°C without HMEs after 120 min of anaesthesia (P < 0.05, between with and without HME). The tympanic membrane temperatures at 120 min of anaesthesia were 35.8 ± 0.6, 35.5 ± 0.6 and 35.4 ± 0.8°C in the groups with HMEs, and 35.8 ± 0.6, 35.3 ± 0.7 and 35.3 ± 0.9°C in the groups without the HMEs (NS). Conclusions: The HMEs improved the inspiratory absolute humidity, relative humidity and temperature of the anaesthetic gases during different fresh gas flows. However, the HMEs were not able to prevent a body temperature drop during low-flow anaesthesia. [source] Measurement and prediction of thermal conductivity for hemp fiber reinforced compositesPOLYMER ENGINEERING & SCIENCE, Issue 7 2007T. Behzad The thermal conductivity of hemp fiber reinforced polymer composites were studied from the steady state temperature drop across samples exposed to a known heat flux. The transverse and in-plane thermal conductivities for oriented and randomly oriented composites for different volume fractions of fiber were investigated. Experimental results showed that the orientation of fibers has a significant effect on the thermal conductivity of composites. To validate the experimental results, the heating tests for the thermal conductivity measurements were simulated by a finite element model using the thermal conductivity values obtained from the experiments. Predicted temperatures show close agreement with measured temperatures. Moreover, the experimental results of thermal conductivities of composites at different directions were compared with two theoretical models and illustrated good agreement between the obtained results and models. POLYM. ENG. SCI. 47:977,983, 2007. © 2007 Society of Plastics Engineers [source] Mechanism for Salt ScalingJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2006John J. Valenza II Over the past 60 years, concrete infrastructure in cold climates has deteriorated by "salt scaling," which is superficial damage that occurs during freezing in the presence of saline water. It reduces mechanical integrity and necessitates expensive repair or replacement. The phenomenon can be demonstrated by pooling a solution on a block of concrete and subjecting it to freeze/thaw cycles. The most remarkable feature of salt scaling is that the damage is absent if the pool contains pure water, it becomes serious at concentrations of a few weight percent, and then stops at concentrations above about 6 wt%. In spite of a wealth of research, the mechanism responsible for this damage has only recently been identified. In this article, we show that salt scaling is a consequence of the fracture behavior of ice. The stress arises from thermal expansion mismatch between ice and concrete, which puts the ice in tension as the temperature drops. Considering the mechanical and viscoelastic properties of ice, it is shown that this mismatch will not cause pure ice to crack, but moderately concentrated solutions are expected to crack. Cracks in the brine ice penetrate into the substrate, resulting in superficial damage. At high concentrations, the ice does not form a rigid enough structure to result in significant stress, so no damage occurs. The morphology of cracking is predicted by fracture mechanics. [source] Internal-loss-limited maximum operating temperature and characteristic temperature of quantum dot laserLASER PHYSICS LETTERS, Issue 4 2007L. Jiang Abstract Carrier-density-dependent internal optical loss sets an upper limit for operating temperatures and considerably reduces the characteristic temperature of a quantum dot laser. Such internal loss also constrains the shallowest potential well depth and the smallest tolerable size of a quantum dot at which the lasing can be attained. At the maximum operating temperature or when any parameter of the structure is equal to its critical tolerable value, the characteristic temperature drops to zero. (© 2007 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] A Chandra observation of the disturbed cluster core of Abell 2204MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 3 2005J. S. Sanders ABSTRACT We present results from an observation of the luminous cluster of galaxies Abell 2204 using the Chandra X-ray Observatory. We show the core of the cluster has a complex morphological structure, made up of a high-density core (ne, 0.2 cm,3) with flat surface brightness, a surrounding central plateau, a tail-like feature, wrapping around to the east, and an unusual radio source. A temperature map and deprojected profile shows that the temperature rises steeply outside these regions, until around ,100 kpc where it drops, then rises again. Abundance maps and profiles show that there is a corresponding increase in abundance at the same radius as where the temperature drops. In addition, there are two cold fronts at radii of ,28 and 54.5 kpc. The disturbed morphology indicates that the cluster core may have undergone a merger. However, despite this disruption, the mean radiative cooling time in the centre is short (,230 Myr) and the morphology is regular on large scales. [source] | |||||||||||||