scholarly journals Temperature Difference Effect between Two Samples Ends on the Inception of Thermal Sensitivity

2019 ◽  
Vol 27 (2) ◽  
pp. 183-193
Author(s):  
Ridha Hameed Majeed
Keyword(s):  
Heat Transfer ◽  
Thermal Diffusivity ◽  
Temperature Difference ◽  
Thermal Sensitivity ◽  
Convection Heat Transfer ◽  
The Body ◽  
The Other ◽  
Transient Heat Transfer ◽  
Two Samples ◽  
The Difference

This paper examined the effect of the difference between the temperature of the two end of the body exposed to transient conduction heat transfer on the inception of thermal sensitivity and at different distances from the hot end of the sample. The study was based on the selection of a sample with a length of 15 cm and a fixed height of 1 cm. Four materials with different thermal properties were selected. One end of the model was exposed to three different temperatures (75, 125, and 175) oC. The other end of the sample was placed under a convection heat transfer at 25 oC. To adopt an inception indicator of thermal sensitivity of the sample when exposed to transient heat transfer, (26) oC was used because it is the nearest temperature to the initial condition of the sample. Four points were selected on different distance from hot end along the sample. The hot end temperature was also adopted as an indicator to measure the effect of the temperature difference for two body ends as the other end is subject to constant transient heat transfer.   Determine the effect of the temperature difference   between two body ends exposed to transient heat transfer on the inception of thermal sensitivity is study target. The  results of this study showed  the reverse effect of the temperature difference   between two body ends  exposed to transient heat transfer on the inception of thermal sensitivity, this effect increases by increasing the distance from  hot sample end   and depressing of thermal diffusivity. The results also showed that the values of the Thermal sensitivity inception ranged between (0.43-17845) seconds according to the    distance from the hot end, its temperature, and the thermal diffusivity of sample materials for each case.

scholarly journals Investigation of transient heat transfer in composite walls using carbon/epoxy composites as an example

2015 ◽  
Vol 36 (4) ◽  
pp. 87-105
Author(s):  
Janusz Terpiłowski ◽  
Bartosz Gawron ◽  
Grzegorz Woroniak
Keyword(s):  
Heat Transfer ◽  
Thermal Diffusivity ◽  
Room Temperature ◽  
Similarity Theory ◽  
Complex Structure ◽  
Epoxy Composites ◽  
Transient Heat Transfer ◽  
Flash Method ◽  
Two Samples ◽  
Composite Walls

Abstract The paper presents the application of similarity theory to investigations of transient heat transfer in materials with complex structure. It describes the theoretical-experimental method for identification and design of the structure of two-component composite walls based on the research of the thermal diffusivity for the composite and its matrix separately. The thermal diffusivity was measured by means of the modified flash method. The method was tested on two samples of double-layer ‘epoxy resin – polyamide’. All the investigated samples had the same diameter of 12 mm and thickness ranging from 1.39–2.60 mm and their equivalent value of thermal diffusivity ranging from (1.21–1.98)×10−7 m2/s. Testing the method and research on carbon/epoxy composites was carried out at temperatures close to room temperature.

scholarly journals The Respiration of some Planktonic copepods II. The Effect Of Temperature

1953 ◽  
Vol 31 (3) ◽  
pp. 447-460 ◽  
Author(s):  
D. T. Gauld ◽  
J. E. G. Raymont
Keyword(s):  
Respiratory Rate ◽  
The Body ◽  
The Other ◽  
Effect Of Temperature ◽  
Acartia Clausi ◽  
Temora Longicornis ◽  
Different Temperatures ◽  
Planktonic Copepods ◽  
The Difference ◽  
The Relationship

The respiratory rates of three species of planktonic copepods, Acartia clausi, Centropages hamatus and Temora longicornis, were measured at four different temperatures.The relationship between respiratory rate and temperature was found to be similar to that previously found for Calanus, although the slope of the curves differed in the different species.The observations on Centropages at 13 and 170 C. can be divided into two groups and it is suggested that the differences are due to the use of copepods from two different generations.The relationship between the respiratory rates and lengths of Acartia and Centropages agreed very well with that previously found for other species. That for Temora was rather different: the difference is probably due to the distinct difference in the shape of the body of Temora from those of the other species.The application of these measurements to estimates of the food requirements of the copepods is discussed.

scholarly journals PRE AND POSTPRANDIAL THERMOGRAPHIC PROFILE OF GREEN IGUANAS (IGUANA IGUANA)

2016 ◽  
Vol 73 (2) ◽  
pp. 425
Author(s):  
Simona Rusu ◽  
Zdenek Knotek ◽  
Radu Lacatus ◽  
Ionel Papuc
Keyword(s):  
Heat Transfer ◽  
Body Temperature ◽  
Temperature Difference ◽  
The Body ◽  
Significant Difference ◽  
Before And After ◽  
Significant Temperature ◽  
Green Iguanas ◽  
The Right ◽  
Head Temperature

Abstract The body temperature of 10 clinically healthy green iguanas (Iguana iguana) was measured using a thermographic camera (FLIR E6, Flir Systems Sweden) before and after the food was offered. For each animal there were performed a total of 6 measurements (3 before feeding and 3 after the food was offered). The purpose of this experiment was to observe the thermographic pattern of the body before and after the feeding, since herbivore reptiles tend to bask after the feeding to increase the body temperature that will help them afterwards digest the food. The animals were housed in individual vivariums with every animal having a basking spot available. The pictures were taken outside the vivarium in an adjacent room. The animals were handled with gloves and transported in a cardboard box in order to avoid heat transfer between the handler and the iguana that would have produced thermal artefacts. Each individual was placed on a table on a styrofoam slate, again, to avoid the heat transfer between the table and the animal`s body. For each animal a total of 4 pictures were taken (up, front, left and right). The pictures were analysed with the FLIR Tools program that is provided by the manufacturer and 3 temperatures were taken into consideration (the head temperature, body temperature on the right side and body temperature on the left side). The temperatures were compared between them and with the temperature of the vivariums that consisted of the average between the temperature in 3 different spots (basking spot, the feeding bowl site and the coldest spot) measured with an infrared thermometer GM300 (Benetech, China). The temperature of the body was dependent on the vivarium temperature and it was a significant temperature difference between the measurements before the feeding and after the feeding. Also we discovered a significant difference between the head temperature and the body temperature on the left side before the feeding that disappeared after the animals ate. There was also a significant difference between the temperature on right side and on left side of the animals both before and after the feeding. No significant temperature difference was observed between the head and the right side of the body neither before nor after the feeding.

Conditions for Equivalency of Countercurrent Vessel Heat Transfer Formulations

1999 ◽  
Vol 121 (5) ◽  
pp. 514-520 ◽  
Author(s):  
R. B. Roemer
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Temperature Difference ◽  
Bulk Temperature ◽  
Transfer Coefficients ◽  
Bulk Fluid ◽  
Heat Transfer Coefficients ◽  
The Difference ◽  
Convective Heat Transfer Coefficients

Previous models of countercurrent blood vessel heat transfer have used one of two, different, equally valid but previously unreconciled formulations, based either on: (1) the difference between the arterial and venous vessels’ average wall temperatures, or (2) the difference between those vessels’ blood bulk fluid temperatures. This paper shows that these two formulations are only equivalent when the four, previously undefined, “convective heat transfer coefficients” that are used in the bulk temperature difference formulation (two coefficients each for the artery and vein) have very specific, problem-dependent relationships to the standard convective heat transfer coefficients. (The average wall temperature formulation uses those standard coefficients correctly.) The correct values of these bulk temperature difference formulation “convective heat transfer coefficients” are shown to be either: (1) specific functions of (a) the tissue conduction resistances, (b) the standard convective heat transfer coefficients, and (c) the independently specified bulk arterial, bulk venous and tissue temperatures, or (2) arbitrary, user defined values. Thus, they are generally not equivalent to the standard convective heat transfer coefficients that are regularly used, and must change values depending on the blood and tissue temperatures. This dependence can significantly limit the convenience and usefulness of the bulk temperature difference formulations.

XXI. Description of a hydropneumatic baroscope

1839 ◽  
Vol 129 ◽  
pp. 425-431
Keyword(s):  
Thin Sheet ◽  
Simple Calculation ◽  
The Body ◽  
The Other ◽  
Floating Body ◽  
Convex Side ◽  
The Difference ◽  
Increased Pressure ◽  
Brass Wire

The principle on which the instrument I am about to describe is constructed, is, that the volume of a given quantity of air under a constant temperature, is inversely as the pressure to which it is subjected ; and the means I employ to estimate the change of volume which that quantity of air undergoes, by being subjected to differences of pressure caused by a change of elevation, are the determination of the difference of weight which a floating body is capable of sustaining in both situations. Thus, if a vessel containing a quantity of air and water be floated in water, and there be a com­munication between the water in the floating body and that in which it floats, it will follow, that when such an apparatus is subjected to diminished pressure, the air within the float will dilate, and cause a volume of water equal in amount to the dilatation of the air to be driven from the float; and the difference of weight which the floating body will sustain, will be the exact weight of the water expelled : if such an appa­ratus is subjected to an increased pressure, the air within it will contract, and consequently a quantity of water, from that in which it floats, will enter the float, and the diminished weight it is capable of sustaining will be the weight of the water which has entered the float, in consequence of the diminution of the volume of the air. It is by such means, with the instrument immediately to be described, and by the help of a very simple calculation, that I propose to determine the difference of level between any two places. Plate X. fig. 1. represents the floating part, made of thin sheet brass, the body of which ( a ), in form the frustum of a cone, is nine inches long, two inches in dia­meter at one end, and one inch at the other, and capable of containing about fourteen cubic inches. In the centre of the widest end, a small stud of brass ( b ) is hard sol­dered, into which a brass wire ( c ) is screwed, an inch and three-eighths long, and about one twenty-fifth or one thirtieth of an inch in diameter : the other end of the wire is screwed into a brass stud in the middle of the convex side of a shallow cup ( d ), made also of brass, and as light as possible, so that it will retain its shape, and be capable of sustaining a weight of about eight hundred or one thousand grains.

scholarly journals THE CULTIVATION OF TRICHOMONAS OF THE HUMAN MOUTH (TETRATRICHOMONAS HOMINIS)

1917 ◽  
Vol 25 (2) ◽  
pp. 341-347 ◽  
Author(s):  
Tokuzo Ohira ◽  
Hideyo Noguchi
Keyword(s):  
Cultural Studies ◽  
Cell Body ◽  
Trichomonas Vaginalis ◽  
The Body ◽  
The Other ◽  
Other Hand ◽  
Deep Groove ◽  
Different Types ◽  
The Difference

Trichomonades from the mouth were studied by Steinberg who proposed to group them into three distinct types; namely, Trichomonas elongata, Trichomonas caudata, and Trichomonas flagellata. Doflein (3) regards them as probably identical with Trichomonas hominis. Opinions differ as to whether or not Trichomonas vaginalis Donné and Trichomonas hominis Grassi are the same species. Lynch, for instance, believes that they are the same species, while von Prowazek (4), Bensen (5), and others (6, 7) insist that they are different types. Bensen's view seems to be well supported by the difference alleged to be found between the mode of encystment in the two trichomonades, were it not for the fact that our knowledge about the so called cyst of trichomonades is still obscure. According to Alexeieff (8) many of the so called cysts were evidently blastomyces contained in the cell body of the trichomonas. An autogamy alleged to take place in cysts as described by Bohne and von Prowazek (9) has not been confirmed by Dobell (10). And Wenyon (11) contends that it has never been found possible to produce any development of these cysts outside the body on the warm stage as can be done with the cysts of Entamœba coli. Therefore, it is still premature to take the process of encystment into consideration as far as the classification of trichomonas is concerned. On the other hand, Rodenwaldt (12) seems to think that there are many species of trichomonas in the human intestines, and Wenyon has described a new trichomonas from the human intestines (Macrostoma mesnili Wenyon). Further cultural studies in the morphology and biology of these organisms must be carried out in order to solve these problems. In the light of modern investigations there are five subgenera to be included under the genus Trichomonas Donné. They are as follows: (1) Protrichomonas Alexeieff, with three anterior flagella, without an undulating membrane. (2) Trichomastix Biitschli) with three anterior flagella and a trailing flagellum (Schleppgeissel) without an undulating membrane. (3) Trichomonas Donné, with three anterior flagella and an undulating membrane. (4) Macrostoma Alexeieff, Amend, Wenyon (11), with three anterior flagella and an undulating membrane wedged in a deep groove (peristome). (5) Tetratrichomonas Parisi (13), with four anterior flagella and an undulating membrane. As far as our culture trichomonas from the human mouth is concerned, it has been shown that it is not strictly a trichomonas and that it should be classed under the subgenus Tetratrichomonas.

Heat Transport Capability in an Oscillating Heat Pipe

2008 ◽  
Vol 130 (8) ◽  
Author(s):  
H. B. Ma ◽  
B. Borgmeyer ◽  
P. Cheng ◽  
Y. Zhang
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Experimental Investigation ◽  
Heat Pipe ◽  
Temperature Difference ◽  
Convection Heat Transfer ◽  
Power Input ◽  
Film Condensation ◽  
Oscillating Heat Pipe ◽  
Oscillating Motion

A mathematical model predicting the oscillating motion in an oscillating heat pipe is developed. The model considers the vapor bubble as the gas spring for the oscillating motions including effects of operating temperature, nonlinear vapor bulk modulus, and temperature difference between the evaporator and the condenser. Combining the oscillating motion predicted by the model, a mathematical model predicting the temperature difference between the evaporator and the condenser is developed including the effects of the forced convection heat transfer due to the oscillating motion, the confined evaporating heat transfer in the evaporating section, and the thin film condensation in the condensing section. In order to verify the mathematical model, an experimental investigation was conducted on a copper oscillating heat pipe with eight turns. Experimental results indicate that there exists an onset power input for the excitation of oscillating motions in an oscillating heat pipe, i.e., when the input power or the temperature difference from the evaporating section to the condensing section was higher than this onset value the oscillating motion started, resulting in an enhancement of the heat transfer in the oscillating heat pipe. Results of the combined theoretical and experimental investigation will assist in optimizing the heat transfer performance and provide a better understanding of heat transfer mechanisms occurring in the oscillating heat pipe.

Optimum Plate Spacings for Laminar Natural Convection Heat Transfer From Parallel Vertical Isothermal Flat Plates

1971 ◽  
Vol 93 (4) ◽  
pp. 463-465 ◽  
Author(s):  
E. K. Levy
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Temperature Difference ◽  
Maximum Rate ◽  
Convection Heat Transfer ◽  
Natural Convection Heat Transfer ◽  
Convection Heat ◽  
Flat Plates ◽  
Plate Spacing ◽  
Laminar Natural Convection

The problem of determining the optimum spacings between parallel vertical isothermal flat plates which are dissipating heat by natural convection to the environment is discussed. One optimum, first suggested by experimental data of Elenbaas with air and later derived theoretically by Bodoia, corresponds to the spacing between parallel vertical plates attached to a surface which will permit the maximum rate of heat transfer from that surface. A different optimum is derived in this paper which for a given heat flux gives the minimum plate spacing required to minimize the temperature difference between the plates and the fluid. The minimum temperature difference is shown to occur when the plate spacing is made sufficiently large that the wall boundary layers do not merge. It is shown that Elenbaas’ optimum, although requiring a plate spacing only 54 percent of that for minimum ΔT, produces a temperature difference which is 38 percent higher than the minimum.

scholarly journals EXPERIMENTAL STUDY OF CONCRETE PERFORMANCE

2020 ◽  
Vol 2 (1) ◽  
pp. 48-61
Author(s):  
Sang Kee ◽  
Yuhee Park ◽  
Eun Choi
Keyword(s):  
Experimental Study ◽  
Compressive Strength ◽  
Rice Husk ◽  
Rice Husk Ash ◽  
Strength Test ◽  
The Other ◽  
Average Score ◽  
Two Samples ◽  
The Difference ◽  
B Test

This study was experimental in nature and conducted with the view to make comparison between two samples. The first sample consisted of concrete with rice husk ash mixed in it and the other sample was without such addition. The first test conducted to test the performance was simple measurements. The results show that for the sample without addition of rice husk ash, the density was 2355.97 and for included sample, the density was 2354.44 with insignificant differences (t-stat= 0.766, P>.05). For V-B test, the sample without addition of rice husk as was 8.34 and for include sample, it was 8.01. The differences for V-B for both samples were statistically insignificant (t-stat=1.431, P>.05). The slump test without for the sample without addition of rice husk was 12.75 and for included sample, it was 18.56. The difference was statistically significant (t-stat=2.455, P<.05). The compressive strength for excluded sample was 24.32 and for included sample was 20.01. The results were statistically insignificant (t-value= 1.13, P>.05). For flexural strength test, for excluded sample, the average score was 9.02 and for included sample, the average score was 9.19. The difference was statistically insignificant (t-stat=1.45, P>.05). Overall, the results lead to the conclusion that there are insignificant differences of addition of rice husk ash in concrete.

scholarly journals Convection Heat Transfer Analysis in a Channel with an Open Trapezoidal Cavity: Heat Source Locations effect

2020 ◽  
Vol 330 ◽  
pp. 01006
Author(s):  
F. Mebarek-Oudina ◽  
H. Laouira ◽  
A. Aissa ◽  
A. K. Hussein ◽  
M. El Ganaoui
Keyword(s):  
Heat Transfer ◽  
Heat Source ◽  
Numerical Study ◽  
Convection Heat Transfer ◽  
The Other ◽  
Heat Transfer Analysis ◽  
Convection Heat ◽  
Nusselt Numbers ◽  
Discrete Heat Source ◽  
Trapezoidal Enclosure

In this work, a numerical study of mixed convection inside a horizontal channel with an open trapezoidal enclosure subjected to a discrete heat source in different locations is carried out. The heat source with the length of ε = 0.75, is maintained at a constant temperature. The air flow with a fixed velocity and a cold temperature enters the channel horizontally. The other walls of the enclosure and the channel are adiabatic. The results are presented in the form of the contours of velocity, isotherms and Nusselt numbers profiles for various heat source locations, Prandtl number (Pr = 0.71) and Reynolds number (Re = 100) respectively. The distribution of the isotherms depends significantly on the position of the heat source. We noted that the best heat transfer is detected where the heat source is placed in the top of the left .

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