The Prediction of Human Thermal Tolerance When Using a Ventilating Garment With an Antiexposure Suit

1960 ◽  
Vol 82 (3) ◽  
pp. 243-250
Author(s):  
J. W. Mc Cutchan
Keyword(s):  
Thermal Resistance ◽  
Thermal Tolerance ◽  
Heat Storage ◽  
Human Subjects ◽  
Physiological Responses ◽  
Cooling Power ◽  
Heart Rates ◽  
Thermal Environments ◽  
Tolerance Chart ◽  
Composite Indexes

The physiological responses of human subjects have been investigated in the thermal environments ranging from 120 to 240 deg F while wearing the MA-2 ventilating garment, an MK-IV exposure suit, and other garments comprising 2.15 clo2 of thermal resistance. The ventilating garment was given air inputs ranging from 2 to 14 cfm in volume, and from 50 to 90 F in temperature. The thermal responses of the subjects are shown graphically in terms of heat storage, heart rates, sweat rates, and composite indexes of these variables. The results of these experiments have been prepared in terms of an equation which is presented graphically as a nomograph. This nomograph predicts the cooling power of the MA-2 ventilating garment and is to be used in conjunction with the tolerance chart. The tolerance data, which were determined on steady exposures in a preheated chamber, are used to predict human tolerance for conditions where the air and wall temperatures are not constant.

Influence of selected factors on parameters of a cooling system with a Peltier module and forced air flow

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Krzysztof Posobkiewicz ◽  
Krzysztof Górecki
Keyword(s):  
Thermal Resistance ◽  
Heat Sink ◽  
Cooling System ◽  
Heat Sinks ◽  
Cooling Power ◽  
Cooling Systems ◽  
Content Type ◽  
Peltier Module ◽  
Peltier Modules ◽  
Forced Air

Purpose The purpose of this study is to investigate the validation of the usefulness of cooling systems containing Peltier modules for cooling power devices based on measurements of the influence of selected factors on the value of thermal resistance of such a cooling system. Design/methodology/approach A cooling system containing a heat-sink, a Peltier module and a fan was built by the authors and the measurements of temperatures and thermal resistance in various supply conditions of the Peltier module and the fan were carried out and discussed. Findings Conclusions from the research carried out answer the question if the use of Peltier modules in active cooling systems provides any benefits comparing with cooling systems containing just passive heat-sinks or conventional active heat-sinks constructed of a heat-sink and a fan. Research limitations/implications The research carried out is the preliminary stage to asses if a compact thermal model of the investigated cooling system can be formulated. Originality/value In the paper, the original results of measurements and calculations of parameters of a cooling system containing a Peltier module and an active heat-sink are presented and discussed. An influence of power dissipated in the components of the cooling system on its efficiency is investigated.

Pregnancy-induced changes in the maximal physiological responses during swimming

1991 ◽  
Vol 71 (4) ◽  
pp. 1454-1459 ◽  
Author(s):  
R. G. McMurray ◽  
A. C. Hackney ◽  
V. L. Katz ◽  
M. Gall ◽  
W. J. Watson
Keyword(s):  
Pregnant Women ◽  
Plasma Volume ◽  
Physiological Responses ◽  
Cycle Ergometry ◽  
O2 Uptake ◽  
Heart Rates ◽  
Capillary Dynamics ◽  
Exercise Induced ◽  
Induced Changes

The effect of pregnancy on peak O2 uptake (VO2 peak) during tethered swimming was evaluated in 10 women during their 25th and 35th wk of pregnancy, as well as 9–11 wk postpartum. The swim results were compared with cycle ergometry results obtained at similar times. The results indicated that exercise-induced maximal heart rates remained the same and were similar for the swim and cycle trials, approximately 184 +/- 4 beats/min. Cycling VO2 peak was not affected by pregnancy, averaging 1.94 +/- 0.11 l/min. Postpartum swim VO2 peak was similar to the cycle results; however, during pregnancy it was significantly lower than cycling VO2 peak (P less than 0.05; postpartum, 1.78 +/- 0.14 l/min; 25th wk, 1.64 +/- 0.12; 35th wk, 1.48 +/- 0.11). Hemoglobin concentrations and hematocrits were lower during pregnancy; however, changes in plasma volume (based on hematocrit and hemoglobin) were found to be significantly greater during cycling than during swimming and also greater during pregnancy for both modes of exercise. It was concluded that, unlike cycling, the VO2 peak of pregnant women during swimming is reduced. This reduction in VO2 peak was associated with a decreased peak ventilation (r = 0.864) but was not correlated to exercise-induced hemoconcentration (r = -0.29). Furthermore, pregnancy results in a greater-than-normal exercise-induced hemoconcentration, which may be related to pregnancy-induced changes in capillary dynamics.

scholarly journals Assessing thermal resistance of wet suits on human subjects during aquatic activity by a heat flux method

2015 ◽  
Vol 4 (S1) ◽  
Author(s):  
Bernard Redortier ◽  
Emmanuelle Brossard ◽  
Remi Tillol ◽  
Remi Goffinet
Keyword(s):  
Heat Flux ◽  
Thermal Resistance ◽  
Human Subjects ◽  
Flux Method

Transferred-Substrate InGaAsP-Based Thermionic Emission Coolers

2000 ◽  
Author(s):  
Christopher J. LaBounty ◽  
Gerry Robinson ◽  
Patrick Abraham ◽  
Ali Shakouri ◽  
John E. Bowers
Keyword(s):  
Thermal Resistance ◽  
Three Dimensional ◽  
Thermionic Emission ◽  
Copper Film ◽  
Cooling Power ◽  
Material System ◽  
Inp Substrate ◽  
Order Of Magnitude ◽  
Thin Copper Film ◽  
Thermally Conducting

Abstract Most optoelectronic devices are based on III-V semiconductors such as the InP/InGaAsP material system. Solid state refrigerators based on the same material system can be monolithically integrated with optoelectronics. Thermionic emission cooling in InGaAsP-based heterostructures has been shown experimentally to provide cooling power densities of several 100 W/cm2. Cooling by several degrees across thin films on the order of a micron thick has been demonstrated. Thermionic emission of hot electrons over heterobarriers allows for enhanced cooling power beyond what is possible from the bulk thermoelectric properties. The thermal resistance of the InP substrate between the hot side of the thin film cooler and the heat sink is found to be a limitation in cooler performance. Several possibilities are examined for replacing the InP substrate with a higher thermally conducting one such as silicon, copper, or even diamond, and a process for substrate transfer to a thin copper film has been developed. Three-dimensional simulations predict an order of magnitude improvement in the thermal resistance of the substrate. Experimental results of packaged InGaAsP coolers with copper substrates will be discussed.

Comparison of physiological responses of women and men to isometric exercise

1975 ◽  
Vol 38 (5) ◽  
pp. 863-868 ◽  
Author(s):  
J. S. Petrofsky ◽  
R. L. Burse ◽  
A. R. Lind
Keyword(s):  
Blood Pressure ◽  
Older Women ◽  
Diastolic Pressure ◽  
Handgrip Strength ◽  
Physiological Responses ◽  
Isometric Exercise ◽  
Heart Rates ◽  
Rate Of Increase ◽  
Blood Pressures ◽  
The Difference

The volunteers for this study were 83 women, aged 19–65 yr, drawn from several different occupations. Three minutes after exerting maximal handgrip strength (MVC) each subject held a tension of 40 percent MVC to fatigue. Blood pressures and heart rates were measured before, during, and after the endurance of contraction. Age was associated with a reduction of strength of the women, whereas their endurance at 40 percent at 40 per cent MVC increased. There was evidence that menopause enhanced those age effects for strength and endurance. At rest, age was associated with a decreased heart rate. As expected, the heart rates of all the women increased during the endurance contraction. But that increase was greater for the younger than for the older women, thereby exaggerating the difference due to age already seen at rest. Systolic blood pressure at rest was higher with age and, in a similar manner, that relationship was also exaggerated throughout the isometric contraction. Diastolic blood pressure, however, was not changed with age at rest, and although the diastolic pressure increased during the isometric exercise, the rate of increase was unaffected by age. The results obtained are compared with those from a similarly large number of men examined in identical circumstances.

Performance Investigation of Single Adsorption Refrigeration System Driven by Solar Heat Storage

2018 ◽  
Vol 26 (03) ◽  
pp. 1850025
Author(s):  
Hicham Boushaba ◽  
Abdelaziz Mimet
Keyword(s):  
System Performance ◽  
Heat Storage ◽  
Cooling Capacity ◽  
Operating Conditions ◽  
Coefficient Of Performance ◽  
Solar Irradiation ◽  
Cooling Power ◽  
Condensation Temperature ◽  
Adsorption Refrigeration ◽  
Solar Heat

The aim of this paper is to provide a global study of an adsorption refrigeration machine driven by solar heat storage and collected by parabolic trough collector. The system operates with ammonia (as refrigerant) and activated carbon (as adsorbent). A mathematical model interpreting the progression of the heat and the mass transfer at each element of the prototype has been developed. The solar irradiation and the real ambient temperature variations corresponding to a usual summer day in Tetouan (Morocco) are considered. The system performance is evaluated trough specific cooling power (SCP) as well as solar coefficient of performance (SCOP), which was estimated by a dynamic simulation cycle. The pressure, temperature and adsorbed mass profiles in the Adsorber have been calculated. The effects of significant design and operating parameters on the system performance have been investigated. The results show the capability of our system to realize an encouraging performance and to overcome the intermittence of the adsorption refrigeration machines. For a daily solar irradiation of 18[Formula: see text]MJ[Formula: see text]m[Formula: see text] and operating conditions of evaporation temperature [Formula: see text]C, condensation temperature [Formula: see text]C and generation temperature [Formula: see text]C, the results show that the process could achieve an SCP of 115[Formula: see text]W[Formula: see text]kg[Formula: see text] and it could produce a daily specific cooling capacity of 3310[Formula: see text]kJ[Formula: see text]kg[Formula: see text], whereas its SCOP could attain 0.141.

Acclimatization of Scottish Blackface sheep to cold. 2. Skin temperature, heart rate, respiration rate, shivering intensity and skinfold thickness

1968 ◽  
Vol 10 (1) ◽  
pp. 17-35 ◽  
Author(s):  
A. R. Sykes ◽  
J. Slee
Keyword(s):  
Heart Rate ◽  
Skin Temperature ◽  
Cold Exposure ◽  
Chronic Exposure ◽  
Physiological Responses ◽  
Skinfold Thickness ◽  
Acute Exposure ◽  
Heart Rates ◽  
Ambient Temperatures ◽  
Acute Cold Exposure

Closely shorn Scottish Blackface female sheep aged 9–14 months, half on high plane and half on low plane nutrition, were subjected, in climate chambers, to two short acute cold exposures down to −20°C. The acute exposures were separated by two weeks chronic exposure to a moderately subcriticai temperature (+8°C) or to a thermoneutral temperature (+30°C). Most of the sheep showed a greater resistance to body cooling at the second acute exposure (Slee and Sykes, 1967). This increased resistance to hypothermia, defined as acclimatization, was apparently influenced more by acute than by chronic cold exposure. The present paper deals with changes in skin temperature, heart rate, shivering intensity and skinfold thickness which also resulted from cold exposure, and accompanied acclimatization.After acute cold exposure followed by chronic exposure to +8°C the following changes in these parameters were observed:1. Extremity skin temperatures and heart rates were consistently increased at thermoneutral ambient temperatures.2. Vasoconstriction of the extremities and increased heart rate, both of which normally occur during the early stages of cold exposure, were delayed.3. Heart rates at sub-zero ambient temperatures were increased.4. Cold-induced vasodilatation at sub-zero ambient temperatures was increased.After acute cold treatment alone the intensity of shivering during the second acute exposure was reduced. Also the onset of foot vasoconstriction was slightly delayed.A highly significant relationship was observed between shivering intensity and heart rate during cold exposure.Plane of nutrition had less effect on the physiological responses to cooling than did previous cold experience.It was suggested in discussion that the physiological responses associated with acclimatization were: elevated basal metabolic rate, delayed onset of vasoconstriction and delayed metabolic response to cold, and consequent lowering of the critical temperature. Summit metabolism was also increased and shivering intensity reduced during acute cold exposure. Some of these responses could have resulted from either acute or chronic moderate cold exposure. However their persistence, once induced, appeared to depend upon continued exposure to moderate cold.

Effect of vapor pressure on physiologic strain and body heat storage

1963 ◽  
Vol 18 (4) ◽  
pp. 808-811 ◽  
Author(s):  
John F. Hall
Keyword(s):  
Heart Rate ◽  
Heat Stress ◽  
Vapor Pressure ◽  
Heat Storage ◽  
Sweat Rate ◽  
Human Subjects ◽  
Vapor Pressures ◽  
Physiologic Responses ◽  
Male Subjects ◽  
Body Heat

Physiologic strain, in terms of body heat storage, and other physiologic responses were measured and compared in two series of heat stress experiments performed on human subjects exposed to different ambient vapor pressures. One group of 75 experiments conducted on 5 healthy nonacclimatized male subjects exposed 5 times each to 38, 54, and 71 C at 10 mm Hg vapor pressure was compared with a series of 81 experiments performed on 10 similar subjects exposed 1–6 times each to 38, 41, and 54 C at 20 mm Hg vapor pressure. Subjects were sitting and wore 1.0 clo insulation. The data show relation between body heat storage and a) the modified Craig index of physiologic strain; b) over-all sweat rate; c) evaporative rate; d) sweat-evaporative ratio; e) mean skin and rectal temperatures; and f) change of heart rate at the respective vapor pressure levels. Statistically significant correlation between sweat-evaporative ratio and over-all sweat rate with body heat storage is shown. Use of the over-all sweat response as a physiologic strain index is suggested. Submitted on August 14, 1962

scholarly journals Cardiovascular responses during submaximal cycling with and without left-lateral tilting: insights for practical applications of stress echocardiography

2020 ◽  
pp. 1-4
Author(s):  
Alexander J. Beaumont ◽  
Laura J. Forrest ◽  
Viswanath Unnithan ◽  
Nicholas Sculthorpe
Keyword(s):  
Oxygen Uptake ◽  
Stress Echocardiography ◽  
Physiological Responses ◽  
Cardiovascular Responses ◽  
Heart Rates ◽  
Practical Applications ◽  
Lateral Tilt ◽  
Cardiorespiratory Responses ◽  
Fixed Power ◽  
Lateral Tilting

We investigated the cardiorespiratory responses to semi-supine exercise with (SS+45°) and without (SS-0°) a left-lateral tilt in 15 adults at fixed power output (70 W) and matched heart rates. At 70 W, oxygen uptake and heart rate reduced from upright to SS-0° then increased to SS+45° (p < 0.05). At matched heart rates, oxygen uptake and efficiency were lowest in SS+45° (p < 0.05). Left-lateral tilting should not be performed under the assumption that each position replicates the same cardiorespiratory responses. Novelty: Cardiorespiratory responses to exercise are influenced by left-lateral tilting, which should not be performed under the assumption that physiological responses are replicated between left-lateral positions.

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