P32 Do meteorological factors influence the occurrence of acute aortic dissection?A ten-year retrospective institutional review

2020 ◽  
Vol 41 (Supplement_1) ◽  
Author(s):  
R Usui ◽  
T Yoshizumi ◽  
H Oshima ◽  
A Usui
Keyword(s):  
Logistic Regression ◽  
Aortic Dissection ◽  
Temperature Difference ◽  
Atmospheric Pressure ◽  
Minimum Temperature ◽  
Acute Aortic Dissection ◽  
Meteorological Factors ◽  
Maximum Temperature ◽  
Maximum Temperature Difference ◽  
Cutoff Values

Abstract Purpose Some studies have reported a relationship between meteorological factors and the occurrence of acute aortic dissection (AAD). Nevertheless, the results of the studies are heterogeneous. Furthermore, whether the absolute values or fluctuation of meteorological factors influence the occurrence of AAD remains controversial. The aim of this study was to determine the meteorological factors associated with the occurrence of AAD. Methods Two hundred eighty-two consecutive patients (male, n = 178; female, n = 104; average age, 68 years) admitted to our hospital for AAD in the 10 years from September 1st 2008 were included in this study. One hundred fifty-seven patients had type A dissection. The correlation between the clinical data and the local meteorological data over the same period (provided by the National Meteorological Agency) was analyzed. We compared the following factors on days of AAD occurrence and non-occurrence: minimum and maximum temperature, minimum and maximum temperature difference between day of occurrence and previous day, difference between maximum and minimum temperature, atmospheric pressure and atmospheric pressure difference between day of occurrence and previous day (Δatmospheric pressure), and minimum and maximum temperature difference from climatological standard normal (CSN). Cutoff values were determined by ROC curve analyses and odds ratios (ORs) were calculated by a logistic regression analysis of meteorological factors with statistically significant differences. Results ignificant differences between the days of AAD occurrence and non-occurrence were observed for minimum and maximum temperature (p < 0.0001), atmospheric pressure (p < 0.0001) and Δatmospheric pressure (p = 0.0286), minimum temperature difference from CSN (p < 0.0001), and maximum temperature difference from CSN (p = 0.0010). The cutoff values were as follows: minimum temperature, 4°C; maximum temperature, 15.1°C; atmospheric pressure, 1008.9hPa; Δatmospheric pressure, 0.4hPa; minimum temperature difference from CSN, 1°C; and maximum temperature difference from CSN, -0.2°C. The univariate logistic regression model showed revealed the following significant predictors of the occurrence of AAD; minimum temperature (OR2.42, p < 0.0001), maximum temperature (OR2.23, p < 0.0001), air pressure (OR1.75, p < 0.0001), Δatmospheric pressure (OR 1.44, p = 0.0030), minimum temperature difference from CSN (OR1.80, p < 0.0001) and maximum temperature difference from CSN (OR1.58, p = 0.0003). However, only minimum temperature (OR1.60, 95% CI 1.00-2.53, p = 0.0478) and maximum temperature difference from CSN (OR1.45, 95% CI 1.11-1.89, p = 0.0062) remained significant in the multivariate analysis. Conclusion Meteorological factors, especially a minimum temperature under 4°C strongly influenced the occurrence of AAD. A maximum temperature difference from CSN of over -0.2°C was also a significant predictor of AAD.

MODELING THE EFFECT OF HEAT EXCHANGE ON THE EFFICIENCY OF A THERMOELECTRIC COOLER

2020 ◽  
Vol 2 ◽  
pp. 132-135
Author(s):  
O.I. MARKOV
Keyword(s):  
Numerical Calculation ◽  
Heat Exchange ◽  
Solid State ◽  
Numerical Modelling ◽  
Temperature Difference ◽  
Maximum Temperature ◽  
Thermoelectric Cooler ◽  
Maximum Temperature Difference ◽  
Peltier Cooler ◽  
Account Heat

Numerical modelling thermal and thermoelectric processes in a branch of solid–state thermoelectric of Peltier cooler is performed, taking into account heat exchange by convection and radiation. The numerical calculation of the branch was carried out in the mode of the maximum temperature difference.

Simulation and Optimization of Temperature Field of Tank Cover with Super Large Diameter during the Creep Aging Forming Process

2021 ◽  
Vol 315 ◽  
pp. 3-9
Author(s):  
Yuan Gao ◽  
Li Hua Zhan ◽  
Hai Long Liao ◽  
Xue Ying Chen ◽  
Ming Hui Huang
Keyword(s):  
Temperature Field ◽  
Field Distribution ◽  
Temperature Difference ◽  
Single Stage ◽  
Maximum Temperature ◽  
Heating Process ◽  
Temperature Field Distribution ◽  
Two Stage ◽  
Maximum Temperature Difference ◽  
Forming Accuracy

The uniformity of temperature field distribution in creep aging process is very important to the forming accuracy of components. In this paper, the temperature field distribution of 2219 aluminum alloy tank cover during aging forming is simulated by using the finite element software FLUENT, and a two-stage heating process is proposed to reduce the temperature field distribution heterogeneity. The results show that the temperature difference of the tank cover is large in the single-stage heating process, and the maximum temperature difference is above 27°C,which seriously affects the forming accuracy of the tank cover. With two-stage heating process, the temperature difference in the first stage has almost no direct impact on the forming accuracy of the top cover. In the second stage, the temperature difference of the tank cover is controlled within 10°C, compared with the single-stage heating, the maximum temperature difference is reduced by more than 17°C. The two-stage heating effectively reduces the heterogeneity of the temperature field of the top cover. The research provides technical support for the precise thermal mechanical coupling of large-scale creep aging forming components.

An Unsteady Analysis on Thermal Stratification in the SCS Piping Branched Off the RCS Piping

2003 ◽  
Author(s):  
Kwang-Chu Kim ◽  
Man-Heung Park ◽  
Hag-Ki Youm ◽  
Sun-Ki Lee ◽  
Tae-Ryong Kim ◽  
...  
Keyword(s):  
Temperature Difference ◽  
Thermal Stratification ◽  
Nuclear Power ◽  
Cooling System ◽  
Numerical Study ◽  
Outer Wall ◽  
Maximum Temperature ◽  
Rear Side ◽  
Maximum Temperature Difference ◽  
Starting Point

A numerical study is performed to estimate on an unsteady thermal stratification phenomenon in the Shutdown Cooling System (SCS) piping branched off the Reactor Coolant System (RCS) piping of Nuclear Power Plant. In the results, turbulent penetration reaches to the 1st isolation valve. At 500sec, the maximum temperature difference between top and bottom inner wall in piping is observed at the starting point of horizontal piping passing elbow. The temperature of coolant in the rear side of the 1st isolation valve disk is very slowly increased and the inflection point in temperature difference curve for time is observed at 2700sec. At the beginning of turbulent penetration from RCS piping, the fast inflow generates the higher temperature for the inner wall than the outer wall in the SCS piping. In the case the hot-leg injection piping and the drain piping are connected to the SCS piping, the effect of thermal stratification in the SCS piping is decreased due to an increase of heat loss compared with no connection case. The hot-leg injection piping affected by turbulent penetration from the SCS piping has a severe temperature difference that exceeds criterion temperature stated in reference. But the drain piping located in the rear compared with the hot-leg injection piping shows a tiny temperature difference. In a viewpoint of designer, for the purpose of decreasing the thermal stratification effect, it is necessary to increase the length of vertical piping in the SCS piping, and to move the position of the hot-leg injection piping backward.

Model and Imitation of the Cycle Temperature Fields and Deformations of Coke Drum

2011 ◽  
Vol 197-198 ◽  
pp. 1389-1394
Author(s):  
Sun Yi Chen
Keyword(s):  
Temperature Field ◽  
Temperature Difference ◽  
Cooling Water ◽  
Physical Property ◽  
Temperature Fields ◽  
Maximum Temperature ◽  
Kinetic Temperature ◽  
Maximum Temperature Difference ◽  
Radial Temperature ◽  
Inside Wall

When the operating process of delay coking is cyclically changing from 25°C to 500°C, it would usually induce the effect of heat treatment on the shell of coke drum. After a special model of the kinetic medium climbing along the inside-wall of the coke drum at a steady rate set up, the resulting two-dimensional kinetic temperature field of shell in radial and axial directions has been calculated and analyzed by FEM. The relation between the material physical property of the shell and its temperature has been considered. The results show that the radial temperature difference or the axial temperature difference caused by the cooling water is more than that caused by the hot oil. The maximum temperature difference between the inside-wall and the outside-wall is 40°C below the medium level, 30mm by the hot oil and 60 °C or 25 mm by the cooling water. The circumferential uneven temperature field, location and concave/convex or incline/bend of body have been surveyed and analyzed. The lat-circle deformation of transverse section has been discussed.

scholarly journals PERFORMANCE EVALUATION OF MULTI-PURPOSE MIXED-MODE CABINET SOLAR FOOD PROCESSOR(MCSFP)

2017 ◽  
Vol 5 (3) ◽  
pp. 404-413
Author(s):  
Sravankumar Jogunuri ◽  
Navneet kumar ◽  
Farid Gayasoddin Sayyad ◽  
Valand Pinakin ◽  
Vishal Patel
Keyword(s):  
Performance Evaluation ◽  
Temperature Difference ◽  
Mixed Mode ◽  
Ambient Air ◽  
Maximum Temperature ◽  
Maximum Temperature Difference ◽  
Food Processor ◽  
Fenugreek Leaves

A Multi-Purpose Solar Food Processor (MCSFP) was developed to carryout both cooking and drying operations simultaneously. MCSFP was tested in three different modes of operations ie., for fenugreek leaves drying (M1) and for cooking of rice separately (M2) and drying of fenugreek and cooking of rice together(M3). The maximum temperature difference attained between ambient air and MCSFP dryer and cooker was 23°C and 36.5°C respectively. The temperatures attained are well suited for drying of fenugreek leaves and cooking rice.

scholarly journals On the Efficiency of Using Transpiration Cooling to Mitigate Urban Heat

Climate ◽  
2020 ◽  
Vol 8 (6) ◽  
pp. 69 ◽  
Author(s):  
Kai Gao ◽  
Mattheos Santamouris ◽  
Jie Feng
Keyword(s):  
Temperature Difference ◽  
Sap Flow ◽  
Principal Component ◽  
Sea Breeze ◽  
Maximum Temperature ◽  
Transpiration Cooling ◽  
Maximum Temperature Difference ◽  
Large Trees ◽  
Synoptic Conditions ◽  
Multiple Variables

Trees are considered to be effective for the mitigation of urban overheating, and the cooling capacity of trees mainly comes from two mechanisms: transpiration and shading. This study explores the transpiration cooling of large trees in urban environments where the sea breeze dominates the climate. In the experiment, sap flow sensors were used to measure the transpiration rate of two large trees located in Sydney over one year. Also, the temperature difference between the inside and outside of the canopy, as well as the vertical temperature distribution below the canopy, were measured during summer. In this experiment, the temperature under the canopies decreased by about 0.5 degrees from a 0.5 m height to a 3.5 m height, and the maximum temperature difference between the inside and outside of the canopy was about 2 degrees. After applying a principal component analysis of multiple variables, we found that when a strong sea breeze is the primary cooling mechanism, the sap flow still makes a considerable contribution to cooling. Further, the sea breeze and the transpiration cooling of trees are complementary. In conclusion, the characteristics of synoptic conditions must be fully considered when planting trees for mitigation purposes. Since the patterns of sea breeze and sap often do not coincide, the transpiration cooling of trees is still effective when the area is dominated by sea breeze.

Experimental Investigation of Plastic Injection Molding Heating System Using Hydrogen Absorbing Alloys

2020 ◽  
Author(s):  
Yoshio Fukushima ◽  
Masataka Kosaka
Keyword(s):  
Injection Molding ◽  
Temperature Difference ◽  
Alternative Energy ◽  
Heating System ◽  
Plastic Injection Molding ◽  
Maximum Temperature ◽  
Hydrogen Energy ◽  
Mold Surface ◽  
Maximum Temperature Difference ◽  
Plastic Injection

Abstract Much focus from various fields is being placed on the hydrogen and utilizing the technique. Nowadays, the applied researches of hydrogen energy have been trying as one of an alternative energy source for fossil fuel. And, since we could not think lightly of consumed energy by machine tools and industrial machinery, Eco-friendly manufacturing is going to be achieved by hydrogen energy. In this study, to prevent the weldline that is a representative defect in the field of plastic injection molding, heat & cool technology using hydrogen energy, LmNi4.90Mn0.10 hydride, is applied to the mold. This method can achieve heat & cool technology by using only hydrogen energy. So, since electricity and warm/cool water that are for heating/cooling the mold are not necessary, this method should thus be at an engineering advantage in terms of eco-friendly manufacturing. After manufacturing the hydrogen-used-prototype-mold that is dedicated to preventing the weldline, the comparison between the experimental data and numerical simulation was carried out. As result, using this approach, the mold surface temperature difference from initial temperature was rapidly increasing to 40 K, in 18 seconds from the beginning of hydrogen-absorbing and the maximum temperature difference ΔT in this experiment has become 48 K.

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