scholarly journals STUDIES OF TROPICAL TUNA SWIMMING PERFORMANCE IN A LARGE WATER TUNNEL - THERMOREGULATION

1994 ◽  
Vol 192 (1) ◽  
pp. 33-44 ◽  
Author(s):  
H Dewar ◽  
J Graham ◽  
R Brill
Keyword(s):  
Heat Transfer ◽  
Swimming Performance ◽  
Yellowfin Tuna ◽  
The Body ◽  
Water Tunnel ◽  
Thunnus Albacares ◽  
Ambient Temperatures ◽  
Large Water ◽  
Tropical Tuna ◽  
Intense Activity

The body temperatures (Tb) of nine yellowfin tuna (Thunnus albacares) were monitored while fish swam in a large water tunnel at controlled velocities (U) and ambient temperatures (Ta). Monitoring Tb during step changes in Ta at constant U permitted estimation of the thermal rate coefficient (k), an index of heat transfer. In the yellowfin, k is dependent on both Ta and the direction of the thermal gradient (i.e. whether Ta is greater or less than Tb). Modulation of k in response to Ta was further demonstrated during tests in which U was varied; the elevation of Tb in response to equal increases in U was 3­4 times less at 30 C than at 25 and 20 C. These experiments demonstrate that the yellowfin tuna can modulate heat transfer. This ability could prevent overheating during intense activity, retard heat loss during a descent into cool water and permit increased heat gain upon returning to warm surface waters (i.e. when Tb<Ta).

STUDIES OF TROPICAL TUNA SWIMMING PERFORMANCE IN A LARGE WATER TUNNEL - KINEMATICS

1994 ◽  
Vol 192 (1) ◽  
pp. 45-59 ◽  
Author(s):  
H Dewar ◽  
J Graham
Keyword(s):  
Swimming Performance ◽  
Beat Frequency ◽  
Fork Length ◽  
Swimming Velocity ◽  
Water Tunnel ◽  
Pectoral Fins ◽  
Swimming Mode ◽  
Anatomical Adaptations ◽  
Large Water ◽  
Tropical Tuna

Yellowfin tuna (Thunnus albacares) swimming kinematics was studied in a large water tunnel at controlled swimming velocities (U). Quantified kinematic variables included the tail-beat frequency, stride length (l), caudal amplitude, yaw, the propulsive wavelength, the speed of the propulsive wave (C) and the sweepback angle of the pectoral fins. In general, all variables, except the propulsive wavelength and consequently C, are comparable to values determined for other teleosts. The propulsive wavelength for the tunas (1.23­1.29 L, where L is fork length) is 30­60 % longer than in other cruise-adapted teleosts such as salmonids. The resulting thunniform swimming mode and the morphological and anatomical adaptations associated with the long propulsive wavelength (e.g. fusiform body shape, rigid vertebral column) act to minimize anterior resistance and maximize caudal thrust. The long propulsive wavelength also increases the maximum l which, in concert with the elevated muscle temperatures of tunas, increases their maximum swimming velocity.

scholarly journals STUDIES OF TROPICAL TUNA SWIMMING PERFORMANCE IN A LARGE WATER TUNNEL - ENERGETICS

1994 ◽  
Vol 192 (1) ◽  
pp. 13-31 ◽  
Author(s):  
H Dewar ◽  
J Graham
Keyword(s):  
Swimming Performance ◽  
Standard Metabolic Rate ◽  
Water Tunnel ◽  
Scaling Exponent ◽  
Temperature Dependent ◽  
Katsuwonus Pelamis ◽  
Size Groups ◽  
Large Water ◽  
Euthynnus Affinis ◽  
Tropical Tuna

The metabolic rates (V(dot)O2) of three tropical tunas [yellowfin tuna (Thunnus albacares), kawakawa (Euthynnus affinis) and skipjack (Katsuwonus pelamis)] were estimated using a large water-tunnel respirometer. Experiments lasting up to 31 h were used to determine the effects of velocity (U) on tuna V(dot)O2 over a range of U (17-150 cm s-1) and temperatures (18­30°C). Replicate tests were carried out on several fish. The swimming V(dot)O2 of yellowfin is temperature-dependent (Q10=1.67, determined over intervals of 3­5°C). For yellowfin and skipjack, it was also possible to partition metabolic costs between maintenance and locomotion. The standard metabolic rate (SV(dot)O2) was estimated by extrapolation of the U/V(dot)O2 function to U=0. Comparisons of SV(dot)O2 for different size groups of yellowfin show that the mass-specific scaling exponent for V(dot)O2 is -0.40. The SV(dot)O2 of tuna is comparable to values determined previously by stasis respirometry and is approximately three times higher than that of salmonids. Further comparisons with salmonids show that the slope of the U/V(dot)O2 function is less for tunas, which demonstrate a greater swimming efficiency.

Water-tunnel studies of heat balance in swimming mako sharks

2001 ◽  
Vol 204 (23) ◽  
pp. 4043-4054 ◽  
Author(s):  
Diego Bernal ◽  
Chugey Sepulveda ◽  
Jeffrey B. Graham
Keyword(s):  
Heat Transfer ◽  
Heat Balance ◽  
Underlying Mechanism ◽  
The Body ◽  
Morphological Properties ◽  
Water Tunnel ◽  
Vascular Networks ◽  
Red Muscle ◽  
Counter Current ◽  
New Evidence

SUMMARY The mako shark (Isurus oxyrinchus) has specialized vascular networks (retia mirabilia) forming counter-current heat exchangers that allow metabolic heat retention in certain regions of the body, including the aerobic, locomotor red muscle and the viscera. Red muscle, white muscle and stomach temperatures were measured in juvenile (5–13.6 kg) makos swimming steadily in a water tunnel and exposed to stepwise square-wave changes in ambient temperature (Ta) to estimate the rates of heat transfer and to determine their capacity for the activity-independent control of heat balance. The rates of heat gain of red muscle during warming were significantly higher than the rates of heat loss during cooling, and neither the magnitude of the change in Ta nor the direction of change in Ta had a significant effect on red muscle latency time. Our findings for mako red muscle are similar to those recorded for tunas and suggest modulation of retial heat-exchange efficiency as the underlying mechanism controlling heat balance. However, the red muscle temperatures measured in swimming makos (0.3–3°C above Ta) are cooler than those measured previously in larger decked makos. Also, the finding of non-stable stomach temperatures contrasts with the predicted independence from Ta recorded in telemetry studies of mako and white sharks. Our studies on live makos provide new evidence that, in addition to the unique convergent morphological properties between makos and tunas, there is a strong functional similarity in the mechanisms used to regulate heat transfer.

scholarly journals Influence of Ambient Temperature on Radiative and Convective Heat Dissipation Ratio in Polymer Heat Sinks

Polymers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2286
Author(s):  
Jan Kominek ◽  
Martin Zachar ◽  
Michal Guzej ◽  
Erik Bartuli ◽  
Petr Kotrbacek
Keyword(s):  
Heat Transfer ◽  
Ambient Temperature ◽  
Convective Heat ◽  
Heat Dissipation ◽  
High Surface ◽  
Heat Sinks ◽  
Fourth Power ◽  
Molding Process ◽  
Ambient Temperatures ◽  
University Of Technology

Miniaturization of electronic devices leads to new heat dissipation challenges and traditional cooling methods need to be replaced by new better ones. Polymer heat sinks may, thanks to their unique properties, replace standardly used heat sink materials in certain applications, especially in applications with high ambient temperature. Polymers natively dispose of high surface emissivity in comparison with glossy metals. This high emissivity allows a larger amount of heat to be dissipated to the ambient with the fourth power of its absolute surface temperature. This paper shows the change in radiative and convective heat transfer from polymer heat sinks used in different ambient temperatures. Furthermore, the observed polymer heat sinks have differently oriented graphite filler caused by their molding process differences, therefore their thermal conductivity anisotropies and overall cooling efficiencies also differ. Furthermore, it is also shown that a high radiative heat transfer leads to minimizing these cooling efficiency differences between these polymer heat sinks of the same geometry. The measurements were conducted at HEATLAB, Brno University of Technology.

scholarly journals A Computational Study on the Role of Parameters for Identification of Thyroid Nodules by Infrared Images (and Comparison with Real Data)

Sensors ◽  
2021 ◽  
Vol 21 (13) ◽  
pp. 4459
Author(s):  
José R. González ◽  
Charbel Damião ◽  
Maira Moran ◽  
Cristina A. Pantaleão ◽  
Rubens A. Cruz ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thyroid Nodules ◽  
Numerical Study ◽  
Computational Study ◽  
Internal Heat ◽  
Heat Transfer Process ◽  
The Body ◽  
Physical Parameters ◽  
Infrared Sensors ◽  
Wide Range

According to experts and medical literature, healthy thyroids and thyroids containing benign nodules tend to be less inflamed and less active than those with malignant nodules. It seems to be a consensus that malignant nodules have more blood veins and more blood circulation. This may be related to the maintenance of the nodule’s heat at a higher level compared with neighboring tissues. If the internal heat modifies the skin radiation, then it could be detected by infrared sensors. The goal of this work is the investigation of the factors that allow this detection, and the possible relation with any pattern referent to nodule malignancy. We aim to consider a wide range of factors, so a great number of numerical simulations of the heat transfer in the region under analysis, based on the Finite Element method, are performed to study the influence of each nodule and patient characteristics on the infrared sensor acquisition. To do so, the protocol for infrared thyroid examination used in our university’s hospital is simulated in the numerical study. This protocol presents two phases. In the first one, the body under observation is in steady state. In the second one, it is submitted to thermal stress (transient state). Both are simulated in order to verify if it is possible (by infrared sensors) to identify different behavior referent to malignant nodules. Moreover, when the simulation indicates possible important aspects, patients with and without similar characteristics are examined to confirm such influences. The results show that the tissues between skin and thyroid, as well as the nodule size, have an influence on superficial temperatures. Other thermal parameters of thyroid nodules show little influence on surface infrared emissions, for instance, those related to the vascularization of the nodule. All details of the physical parameters used in the simulations, characteristics of the real nodules and thermal examinations are publicly available, allowing these simulations to be compared with other types of heat transfer solutions and infrared examination protocols. Among the main contributions of this work, we highlight the simulation of the possible range of parameters, and definition of the simulation approach for mapping the used infrared protocol, promoting the investigation of a possible relation between the heat transfer process and the data obtained by infrared acquisitions.

Heat transfer depends on the region of the body and the thickness of the skin

Burns ◽  
2021 ◽  
Author(s):  
Judith C.J. Holzer-Geissler ◽  
Petra Kotzbeck ◽  
Lars-Peter Kamolz
Keyword(s):  
Heat Transfer ◽  
The Body

Influence on Skin Burns by Water Absorbed Station Wear and Underwear in Firefighter Clothing

2013 ◽  
Vol 796 ◽  
pp. 623-629
Author(s):  
Kaoru Wakatsuki ◽  
Norimasa Morii ◽  
Yoshio Ogawa ◽  
Hajime Tsuji
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Evaluation Method ◽  
The Body ◽  
Electric Heater ◽  
Copper Sensor ◽  
Wet Condition ◽  
Transfer Index ◽  
Wear Condition

During firefighting, within firefighter clothing, underwear and station wear gets heavily wet due to firefighting water and moisture from the body. Water has higher thermal conductivity relative to air and it has been expected that heavily wet condition within the firefighter clothing makes faster skin burns. The objective of this study is how the wet condition within a firefighter clothing makes faster heat transfer from feeling pain and to being 2nd degree of skin burns relative to the dry condition in case of routine firefighting operation in a building (up to 20 kW/m2). Aramid station wear and cotton underwear, generally used by a Japanese firefighter, have been selected and cut 0.15 m x 0.15 m to attach an ISO 9151 copper sensor. A cone shape electric heater, which produces 12 kW/m2 to 20 kW/m2, was used to heat the fabrics. Scenario of fabrics are that (1) wet station wear and dry underwear, (2) wet station and wet underwear, (3) dry station wear and wet underwear, and (4) dry station wear and dry underwear. Evaluation method was by a heat transfer index (HTI) by ISO 9151. The time to rise temperature of 12 and 24 °C (HTI12 and HTI24), and heat transfer rate (dT/dt) were investigated for above four scenarios. The result shows that there was significant impact by condition of station wear, but little impact by underwear. In heat transfer rate (dT/dt) analysis, for the situation of feeling pain to the 2nd degree of skin burns (from HTI12 to HTI24), heat transfer rate was about 50% higher relative to the dry station wear condition. This result indicates that it is possible to be 2nd degree of skin burns easily as soon as a firefighter feels the pain, if he/she wears wet station wear.

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