Mathematical Modeling of Human Temperature Regulation During Cold Exposure PDF Download
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Author: Theodore Koreckij
Publisher:
ISBN:
Category : Cold
Languages : en
Pages : 190
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Book Description
Author: Theodore Koreckij
Publisher:
ISBN:
Category : Cold
Languages : en
Pages : 190
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Book Description
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
A mathematical model for predicting shivering and thermoregulatory responses during long term cold exposure has been developed and validated. The basis for this model is a six-cylinder mathematical model of human temperature regulation which was well validated (Xu and Werner, Appl. Human Sci. 16:61-75, 1997) for dynamic conditions: incorporating heat, cold (less than 2 hours), clothing systems, and exercise. To what extent shivering is maintained over a long duration is not clearly known and a modeling technique has been sought to predict such responses.
Author: J. A. J. Stolwijk
Publisher:
ISBN:
Category : Body temperature
Languages : en
Pages : 92
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Author: Jan A. J. Stolwijk
Publisher:
ISBN:
Category : Biological models
Languages : en
Pages : 92
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 25
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Book Description
Immersion in cold water brings about large changes in body temperature and metabolism that add to the complexity of modelling human thermoregulation. Three specific problems peculiar to such modelling are examined; they are 1) finite-difference solution of the bioheat equation; 2) differences between predicted and measured initial conditions; and 3) prediction of convective heat loss. An optimization of the finite-difference solution of the simpler, but related, heat conduction problem is presented. A greater benefit is obtained by increasing the number of nodes rather than decreasing the integration time interval. A procedure is given for matching the predicted and measured initial values of the deep body temperature and the metabolic rate which allows a more accurate determination of set-point values for thermoregulation. To circumvent the acute sensitivity to the skin-water temperature difference using the conventional prediction of convective heat loss, use of a heat balance during steady-state of the skin temperature is outlined. Keywords: Heat stress; Acclimatization; Hypothermia; Computer modeling.
Author: L.G. Meyer
Publisher:
ISBN:
Category :
Languages : en
Pages : 52
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Author: Eugene H. Wissler
Publisher: Springer
ISBN: 3662573970
Category : Medical
Languages : en
Pages : 435
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Book Description
The principal objective of this book is to provide information needed to define human thermal behavior quantitatively. Human thermal physiology is defined using mathematical methods routinely employed by physicists and engineers, but seldom used by physiologists. Major sections of the book are devoted to blood flow, sweating, shivering, heat transfer within the body, and heat and mass transfer from skin and clothing to the environment. Simple algebraic models based on experimental data from a century of physiological investigation are developed for bodily processes. The book offers an invaluable source of information for physiologists and physical scientists interested in quantitative approaches to the fascinating field of human thermoregulation.
Author: Elias Ghadam Soltani
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
In this study, a computational model of the human thermoregulatory system is developed to predict the temperature distribution within tissues, on the skin and the arterial net- work. It is based on an anatomically accurate whole human body geometry comprising various tissue structures, organs and its vascular network. The governing equations that couple energy transfer between the blood and surrounding tissues were implemented in OpenCMISS, an open-source computational library that provides an environment to utilise the nite element method (among other specialised numerical methods) to solve partial di erential equations in complex bioengineering problems. Moreover, an open standard framework built using the XML mark-up language known as CellML was used to impose appropriate regulatory or control actions and update heat transfer mechanisms accordingly. The framework was also used to prescribe di erent types of boundary conditions as it is primarily used to solve di erential-algebraic equations. An extensive literature review is included in this thesis to provide an overview of the existing mathematical models used for studying the thermoregulation of the human body. The review covers the strengths, limitations and scope of ap- plications of these models. The computational model was formulated by coupling the bioheat equation describing the di usion of heat in three-dimensional tissue structures with the energy equation that is responsible for advection and di usion of heat along the one-dimensional blood ow in the arterial network. It can simulate the heat exchange between the body surface and surrounding environment due to conduction, convection, radiation and evapora- tive cooling or moisture transfer. Furthermore, it is capable of simulating blood ow under di erent conditions which is essential for evaluating heat exchange between the blood and surrounding tissues. This functionality of the model allows us to investigate how physiological conditions in the arterial network in uence the human thermal system and a ect its performance. Functionally the model is organised into two subsystems. The passive subsystem pri- marily deals with various modes of heat transport within tissues, between tissues and blood (arterial system and perfusion) and between the body and the surrounding en- vironment. The governing equations that mathematically describe the passive subsys- tem are based on the laws of conservation. The active subsystem, on the other hand, prescribes physiological phenomena in the body, namely, shivering, sweating, vasodila- tion and vasoconstriction and facilitates maintaining the body core temperature. These physiological activities are based on empirical formulations from previous studies. The blood ow and heat transfer included in the passive system was simulated using OpenCMISS and the active system was implemented by using CellML capabilities that enable to input controlling parameters and prescribe and update the boundary conditions to OpenCMISS (passive system). The model results were veri ed against closed-form so- lutions obtained for topologically simple domains and validated against published exper- imental data acquired under controlled conditions. In the latter case, a reasonably good agreement was seen between the model predictions and experimental observations. The structure of the model allows for investigation of the thermoregulatory responses of the human body under a multitude of ambient environmental conditions. Further- more, it would be possible to investigate temperature distribution in the vital organs and skin that can be used to diagnose heat-related conditions and make informed de- cisions to plan suitable treatments. The models capability of simulating the human thermoregulatory system with the abil- ity to obtain realistic skin and internal temperature distribution was demonstrated by considering a number of exposure scenarios. These included neutral condition, high and low temperatures. In all cases, local skin temperature distributions were eval- uated. The e ect of body shape and distribution of the thermophysical properties were also investigated. An important aspect of the current model development is that an open-source code and libraries were used in this thesis research. As such, any contribution made through this study allows other researchers to modify, improve and extend the model for other applications.
Author: Peter Tikuisis
Publisher:
ISBN:
Category :
Languages : en
Pages : 35
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Book Description
A mathematical model of thermoregulation has been developed to simulate human physiological responses to cold-water immersion. Data were obtained from experiments where thirteen healthy male volunteers were totally immersed under resting and nude conditions for 1 h in water temperatures of 20 and 28 C. Mean measured rectal temperature (T sub re) fell by about 0.9 and 0.5 C in 20 and 28 C water for all subjects, yet mean measured metabolic rate (M) rose by about 275 and 90 W for the lean mass group (n=7) and 195 and 45 W for the normal mass group (n=6). To predict the observed T sub re and M values, the present model differed from its predecessors by a) determining a thermally neutral body temperature profile such that the measured and predicted initial values of T sub re and M were matched, b) including thermal inputs for shivering from the skin independent of their inclusion with the central temperature to account for the observed initial rapid rise in M, c) confining the initial shivering to the trunk region to avoid an overly large predicted initial rate of rectal cooling, and d) calculating the steady state of convective heat loss by assuming a zero rate of heat storage in the skin compartment.
Author: Gary N. Byrd
Publisher:
ISBN:
Category : Cold
Languages : en
Pages : 236
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Book Description
