Dynamics Of Temperature Changes Research Articles

Comparison of temperature measurements in esophagus and urinary bladder in comatose patients after cardiac arrest undergoing mild therapeutic hypothermia.

Mild therapeutic hypothermia (MTH) is a recommended method of treatment for comatose out-of-hospital cardiac arrest (OHCA) survivors. However, the proper site of temperature measurement in MTH is still not defined. The aim of this study was to compare temperature measurements in the esophagus and urinary bladder in comatose post-OHCA patients treated with MTH. This temperature comparison protocol was a part of a prospective, observational, multicenter cohort study. The study population included 36 unconscious patients after resuscitation for OHCA. The patient's core temperature was independently measured every hour during MTH in the urinary bladder and in the esophagus. The mean temperature was lower in the esophagus (differences during induction phase: 1.04 ± 0.92°C, p < 0.0001; stabilization phase: 0.54 ± 0.39°C, p < 0.0001; rewarming phase: 0.40 ± 0.47°C, p < 0.0001). Nevertheless, a strong correlation between both sites was found (R2 = 0.83, p < 0.001). The decrease in temperature observed in the esophagus during the induction phase was faster when compared with the urinary bladder (1.09 ± 0.71°C/h vs. 0.83 ± 0.41°C/h; p = 0.002). As a consequence, time to reach temperature < 34.0°C was longer when temperature was measured in the urinary bladder (the difference between medians of the time 1.0 [0-1.5] h, p < 0.001). Urinary bladder temperature measurements may lag behind temperature changes measured in the esophagus. Monitoring temperature simultaneously in the esophagus and in the urinary bladder is an accessible and reliable combination, although esophageal measurements seem to better reflect the dynamics of temperature changes, thus it seems to be more appropriate for MTH control. ClinicalTrials.gov Identifier: NCT02611934.

Features of modeling the combustion processes of flammable liquids with high ignition temperature in FDS software

The article describes the features of modeling the dynamics of fire during the combustion of flammable liquids, linked with dependence of the velocity of spreading along the liquid surface from a large number of factors. The method of computer simulation of combustion processes of flammable liquids with high ignition temperature is viewed via the Fire Dynamics Simulator software on the example of turbine oil. The influence of the linear velocity of flame spreading over the surface of turbine oil on the dynamics of temperature changes of the gaseous medium in the room is explored. The results of dynamic modeling of turbine oil combustion for cases of a simultaneously ignited area of the spilled flammable liquid and spreading of the flame over its surface from the ignition point with a calculated linear speed. The conclusion is made that it is expedient to use the described method for estimating the linear velocity of flame movement over the liquid surface when modeling combustion over large areas of flammable liquids with a high ignition temperature.

Determination of thermal diffusivity of the material by numerical-analytical model of a semi-bounded body

A mathematical description of the material thermal diffusivity aт in a semi-bounded body is proposed with a relatively simple algorithm for its numerical and analytical by solving the inverse problem of thermal conductivity. To solve the problem, it is necessary to obtain the temperature values of the unbounded plate as a result of a thermophysical experiment. A plate can be conditionally considered as a semi-bounded body as long as the Fourier number Fo ≤ Foк (Foк ≈ 0.04–0.06). It is assumed that the temperature distribution over cross-section of the heated layer of the plate R is sufficiently described by a power function whose exponent depends linearly on the Fourier number. A simple algebraic expression is obtained for calculating aт in the time interval ∆τ from the dynamics of temperature change T(Rп , τ) of a plate surface with thickness Rп heated under boundary conditions of the second kind. Temperature of the second surface of the plate T(0, τ) is used only to determine the time of the end of experiment τк. The moment of time τк, in which the temperature perturbation reaches the adiabatic surface x = 0, can be set by the condition T(Rп , τк) – T(0, τ = 0) = 0,1 K. The method of approximate calculation of dynamics of changes in depth of the heated layer R by the values of Rп , τк , and τ is proposed. Calculation of a т for the time interval ∆τ is reduced to an iterative solution of a system of three algebraic equations by matching the Fourier number, for example, using a standard Microsoft Excel procedure. Estimation of the accuracy of a т calculation was made by the test (initial) temperature field of the refractory plate with the thickness Rп = 0.05 m, calculated by the finite difference method under the initial condition T(x, τ = 0) = 300 (0 ≤ x ≤ Rп) at radiation-convective heating. The heating time was 260 s. Calculation of aт, i was performed for 10 time moments τi + 1 = τi + Δτ, τ = 26 s. Average mass temperature of the heated layer for the whole time was T = 302 K. The arithmetic-mean absolute deviation of aт(T = 302 K) from the initial value at the same temperature was 2.8 %. Application of the method will simplify the conduct and processing of experiments to determine the thermal diffusivity of materials.

Determination of Thermal Diffusivity of Material by the Numerical-Analytical Model of a Semi-Bounded Body

A mathematical description of a material’s thermal diffusivity ae in a semi-bounded body is proposed with a relatively simple algorithm for its numerical and analytical calculation by solving the inverse problem of thermal conductivity. To solve the problem, it is necessary to obtain the temperature values of the unbounded plate as a result of a thermophysical experiment. A plate can be conditionally considered as a semi-bounded body as long as Fourier number Fo ≤ Foe (Foe = 0.04–0.06). It is assumed that the temperature distribution over a cross-section of the heated layer of the plate with thickness R is sufficiently described by a power-like function whose exponent depends linearly on the Fourier number. A simple algebraic expression is obtained for calculating ahc in time interval Δτ from the dynamics of temperature change T(Rp, τ) of a plate surface with thickness Rp heated at boundary conditions of the second kind. Temperature T(0, τ) of the second surface of the plate is used only to determine end time τe of the experiment. Moment of time τe, at which the temperature perturbation reaches adiabatic surface x = 0, can be set by the condition T(Rp, τe) – T(0, τ = 0) = 0.1 K. An approximate method of calculating the dynamics of changes in depth of heated layer R by values of Rp, τe, and τ is proposed. The calculation of ahc for time interval Δτ is reduced to an iterative solution of a system of three algebraic equations by matching the Fourier number, for example, using a standard Microsoft Excel procedure. Estimation of the accuracy of calculation of ahc at radiation-convective heating was performed using the initial temperature field of the refractory plate with thickness Rp = 0.05 m, calculated by the finite difference method under initial condition T(x, τ = 0) = 300 (0 ≤ x ≤ Rp). The heating time was 260 s. Calculation of ahc, i has been performed for ten time moments τi + 1 = τi + Δτ, Δτ = 26 s. Average mass temperature of the heated layer for the entire time was τe T = 302 K. The arithmetic-mean absolute deviation of ae (T = 302 K) from the initial value at the same temperature was 2.8%. Application of the method will simplify conducting and processing experiments to determine thermal diffusivity of materials.

Using the copper-foam for thermal conductivity improvement of La0.9Ce0.1Ni5-alloy bed during interaction with hydrogen

One of the main obstacles to the development of hydrogen energy is the problem of heat transfer inside metal hydride beds. Thus, the problem of increasing the metal hydride beds thermal conductivity is of great interest. This study is devoted to the investigation of the hydrogen sorption properties of an intermetallic compound placed in a matrix of foam material. Copper-foam with mass of 8 g was chosen as a matrix for 50 g of powder of activated AB5-type alloy with composition of La0.9Ce0.1Ni5. PCT-isotherms of hydrogen absorption and desorption were measured at temperatures 313, 333 and 353 K. Also, the dynamics of temperature change in the sample was studied when it was heated under vacuum conditions. The obtained data were compared with the results of previous studies conducted under the same conditions for samples of pure alloy and a mixture of alloy with copper powder. It has been concluded that the use of copper-foam to improve the thermal conductivity is promising, but it is necessary to take into account its influence on the hydrogen sorption properties of metal hydrides.

An Algorithm of Mathematical Modeling of Laser-Induced Indirect Thermotherapy of a Baker’s Cyst

Abstract—A thermophysical model of heat transfer from a liquid heated by radiation into biological tissues with a cyst of an individual picture of temperature fields, which takes the parameters of laser radiation, as well as the individual thermodynamic and morphometric characteristics of the object of exposure and its syntopy, into account, is proposed. The model is designed for algorithmization of performance of laser-induced indirect thermotherapy of cavity tumors. A comparison was made between the theoretical prediction of the dynamics of temperature changes in the wall of a Baker’s cyst and the experimental data obtained using a thin needle thermocouple placed through a needle in the center of a cyst filled with liquid, whose dimensions had been previously determined by magnetic resonance imaging. It was shown that at the heat transfer coefficient of 3000 W/(m2 K) the proposed model described the heating of the cyst contents due to heat transfer from its inner wall accurately.

Formation of temperature regime of permafrost soils of the bases of buildings at the territory of multi-storey housing development of the city of Yakutsk

The results of long-term observations of the temperature regime of soils in the territory of the Yakutsk, as the largest city, built under the conditions of permafrost soils are presented. The process of forming the temperature regime of permafrost soils of bases of buildings and structures is considered. The main factors and regularities of the process are analyzed. The dynamics of temperature changes in permafrost soils at a depth of 10 meters over the entire observation period is presented. The results are compared with the data of other researchers. Measures are proposed to improve the monitoring of thermal regime of the foundations of capital buildings under the conditions of preservation of permafrost soils. The tendencies and regularities of the formation of the temperature regime of the soils of the foundations of buildings and structures in the territory of capital construction under the conditions of the cryolithozone are revealed. Relationship with climatic and technogenic impacts, as well as with problems arising during the operation of buildings and structures, has been established. The research results can be taken into account when designing and constructing buildings and structures in other areas of permafrost with similar geocryological conditions. Recommendations on the technical regulation of temperature regime monitoring of permafrost soils of the cryolithozone have been developed.

The Heat Exchange Mathematical Model of Fire in Cable Tunnel Adequacy Research

According to the results of the conducted studies, the adequacy of the mathematical models of cable tunnels for their further use in the study of the temperature regime of the fire was checked. For this purpose, full–scale tests and findings about the dynamics of temperature change in cable tunnels with known geometrical parameters and fire load were conducted at the experimental test site of the Ukrainian Civil Protection Research Institute (Kyiv).In one of the CFD software systems, a mathematical model of a cable tunnel similar to the actual one was created. A computational experiment was conducted. Based on the results of the computational experiment and field tests, the criteria for adequacy (Student's t–criterion, Cochran's Q–criterion, Fisher's F–criterion) and the relative error of the experiments were calculated. On the basis of the analysis, the adequacy of the used mathematical models was studied.In this article, further development of the use of computational experiments to study the heat and mass exchange processes during fires in cable tunnels.

Analysis and Forecasting of the Earth's Temperature Using Methods Mathematical Statistics and Synergetic Information Theory

The dynamics of temperature change in the lower troposphere of the Earth is analyzed. The presence of trend component in temperature dynamics of Earth from 1880-2017 was revealed. The method of forecasting climate warming on Earth in the conditions of the greenhouse effect has been tested. The method of correlation analysis revealed the presence of significant correlations in the Earth's lower troposphere between temperature and carbon dioxide concentration, temperature, and methane concentration. A similar conclusion was also made on the basis of the strong elongation of the shape of the correlation fields between these signs. A linear regression model was used, which made it possible to forecast the change in temperature depending on the carbon dioxide concentration. The temperature dynamics in the lower troposphere of the Earth is analyzed by the methods of the synergetic theory of information using entropy and negentropy. Calculations showed that the behavior of the entropy and negentropy can also predict an anomalous change in the temperature of the Earth.

Температурні показники після кріовпливу, потенційованого дистильованою водою, на експериментальній моделі печінки свині за умов відсутності спланхнічного кровотоку

The efficiency of local cryoeffect on pathological tissue area depends on the values of achieved temperature at a certain depth. This study presents the results on comparative analysis of the dynamics of temperature changes measured by intraoperative four-channel thermocouple unit KVIT-4 at discrete depths of 3, 8, 13 and 18 mm. We carried out two successive cycles of local cryoeffect with preliminary introduction of a distilled water into parenchyma of porcine liver (main group) and without any additional action (control group) in experimental model of porcine liver without splanchnic blood flow. The average temperature in animal liver tissue of the main group at a distance of 3 mm deep from the cryoapplicator operating surface was lower by 35 degrees at the end of the 10th min of cryoeffect of the 2nd cycle if compared with the control (–85.2 and –49.2°C, respectively), at a depth of 8 mm it was lower by 52,5 degrees (–61.1 and –8.5°C, respectively), at 13 mm this index was lower by 51,5 degrees (–59.5 and –3.0°C, respectively), and at 18 mm it was lower by 40,4 degrees (–40.5 and –0.1°C, respectively). An introduction of a distilled water into biological tissue 5 min prior to the initiation of local cryoeffect increased its effectiveness, as evidenced by the reaching of lower temperatures in the areas distant from the operating surface of the cryoapplicator.Probl Cryobiol Cryomed 2017; 27(4): 348–355

Dedicated tool to assess the impact of a rhetorical task on human body temperature

IntroductionFunctional infrared thermal imaging is a method widely used in medicine, including analysis of the mechanisms related to the effect of emotions on physiological processes. The article shows how the body temperature may change during stress associated with performing a rhetorical task and proposes new parameters useful for dynamic thermal imaging measurements Materials and methods29 healthy male subjects were examined. They were given a rhetorical task that induced stress. Analysis and processing of collected body temperature data in a spatial resolution of 256×512pixels and a temperature resolution of 0.1°C enabled to show the dynamics of temperature changes. This analysis was preceded by dedicated image analysis and processing methods ResultsThe presented dedicated algorithm for image analysis and processing allows for fully automated, reproducible and quantitative assessment of temperature changes and time constants in a sequence of thermal images of the patient. When performing the rhetorical task, the temperature rose by 0.47±0.19°C in 72.41% of the subjects, including 20.69% in whom the temperature decreased by 0.49±0.14°C after 237±141s. For 20.69% of the subjects only a drop in temperature was registered. For the remaining 6.89% of the cases, no temperature changes were registered ConclusionsThe performance of the rhetorical task by the subjects causes body temperature changes. The ambiguous temperature response to the given stress factor indicates the complex mechanisms responsible for regulating stressful situations. Stress associated with the examination itself induces body temperature changes. These changes should always be taken into account in the analysis of infrared data.

The Basic Technology of Steaming and Drying of Wood

Drying is a complex heat and mass transfer process which is affected by operating parameters environment and thermophysical properties of wood. Basis for classification of methods of drying is a method of transmission of heat to material. The basic method of drying is convective, but it is accompanied by a conductivity of wood (from the material surface to its center) and thermal radiation. The research investigates the processes of initial heating and steaming of beech wood in the form of profile pieces, which describes the dynamics of change in temperature of wood in general and particularly of surface and inner layers of wood, as well as changing the thermal properties (coefficients of heat-conducting, diffusivity and specific heat capacity) of wood. The change of thermal properties of wood causes the change of heat-exchange criteria of Fourier and Nusselt. So the use of differential equalization of heat-conducting of Fourier is possible only for the certain period of process of heating. Firstly, experimental studies of process of drying of profile workpiece (firewoods) are undertaken with a previous steaming and without a previous steaming; the corresponding sizes of speed of drying, coefficients of moisture conductivity and output of moisture are found. Consequently, taking into account the criterion of Reynolds the coefficient of drying and mass transfer coefficient of Fourier and Nusselt it is possible to synthesize the physical-mathematical model of process of drying. In the course of the study we have elaborated the structure of technological process of drying of firewoods. It is proved to include such successive technological operations as the initial heating, steaming, drying, that allows considerably to intensify mass transfer processes and, to the eventual result, shorten duration of process of drying on 25 % and accordingly to economize the charges of thermal energy. As a conclusion the author proposes structure of the technological process of drying wood that involves the use of environmentally-friendly drying agent for heating and steaming, and drying process steam-air mixture received from the combustion of waste wood. In general, the structure provides an energy saving of realization of technological process and reduces its overall duration.

Dynamics of Temperature Changes in Thermophille Phase of Composting Process in The Aspect of Sanitary Condition of Obtained Material

Abstract A condition of obtaining compost with proper sanitary parameters is achieving the organic recycling process temperature which exceeds 7°C. The objective of the paper was to determine the temperature course in the compost tank for organic recycling of dead poultry in relation to the applied structure forming material. Wheat, oat, barley, rapeseed and corn straw were used as a structure-forming material. A measuring system was equipped with a probe with a temperature sensor with precision of ±0.15°C, transducer and data recorder. Results were prepared with the use of the analysis of variance at the level of significance of α=0.05. Statistically significant differences of the temperature value in the thermophille phase of the composting process between combinations of the experiment were indicated. In all investigated combinations of the experiment, achievement (or exceeding) the temperature value of 70°C of the compost mass was reported.

The use of dynamic thermal analysis to distinguish between genuine and counterfeit drugs

WHO estimates that 10% of drugs are falsified. Economic and health factors arising from the use of counterfeit drugs lead to the development of new methods for distinguishing genuine medicines from falsified ones. The purpose of this study was to develop a new, fast, and inexpensive method to distinguish between original and fake drugs.10 counterfeit Viagra® tablets were compared to 4 original pills (Pfizer). The drugs – both original and fake – were heated to 60°C and then the dynamics of their temperature changes at ambient conditions was tested using a thermal imaging camera. The time constants τ showing the dynamics of temperature changes for Viagra® and the falsified drug were determined.The thermokinetic parameters of drugs were determined in the temperature range of 60–22.2°C. Both original and counterfeit tablets had different time constants: 171.44±4.62s and 182.71±4.05s, respectively. Differences in the dynamics of temperature changes as a function of time are particularly pronounced in the range of t+2 to t+7min.The comparison of the time constants τ enables to distinguish between genuine and counterfeit drugs. The proposed new method which uses dynamic thermal analysis is an effective, cheap and fast technique to distinguish genuine drugs from counterfeit ones.

Temperature changes in selected areas of body surface induced by systemic cryostimulation.

The aim of this study was to assess the distribution and dynamics of temperature changes on the surface of selected body parts after systemic cryostimulation. The changes that occurred as a reaction to the 1st, 5th, and 10th session of a series of 10 sessions were also analyzed. The study group consisted of 24 students (12 women and 12 men, ∼21 yr of age) from the University School of Physical Education in Krakow. They were treated in a cryogenic chamber at the Rehabilitation Center in Krakow once daily for 10 d. The mean temperature in the chamber was -130°C ± 10°C and the session duration was 3 min. Thermovisual examination of temperature distribution in the selected parts of the upper and lower extremities was conducted before and immediately after a session on the 1(st) (S1), 5(th) (S2), and 10(th) (S3) day of treatment. All thermograms were digitally recorded using a Flir Therma CAM TM Sc500 camera. On the 5th day of treatment, the examined group demonstrated the smallest mean temperature changes (4.57°C-17.31°C for the anterior part of the upper extremities in men and the posterior part of the lower extremities in women, respectively) before and after cryostimulation. The most significant temperature changes were observed in the group of women (6.80°C-20.08°C for the posterior parts of the upper extremities on S2 and the lower extremities on S3, respectively). There is an important difference in response to cryogenic temperature between men and women in a series.

Assessment of the influence of shortening the duration of TRT (thermal response test) on the precision of measured values

In this paper the results of testing thermal parameters of the rock environment and measurement of borehole temperature profiles of the newly constructed experimental underground heat storage (BTES (Borehole Thermal Energy Storage)) in Paskov (Czech Republic) obtained with the TRT (thermal response method) and temperature measurement on boreholes at selected depth levels are summarised. The TRT measurement series on eight boreholes has shown the possibility to compare the differences among individual measurements in a practically identical rock environment. The temperature profiling of boreholes enabled studying the dynamics of temperature changes occurring in the rock environment as a reaction to the heat supply during the TRT.The measurement series was performed with the aim to assess the possibility of shortening the TRT duration while maintaining the acceptable precision of the measured results. For this reason the software simulation of shortening the TRT duration to 24 h was performed, and the influence of such shortening to the precision of determination of values λ and RB was studied. The simulation has shown that shortening the test to 24 h in our case would have brought an acceptable amount of inaccuracy with regard to the dispersion of measured values obtained from the real test.

Вплив теплових процесів в Si/AIIIBV RGB-матрицях світлодіодів на реверсивне мікропроцесорне управління освітленням

Обґрунтовано необхідність впровадження монолітно інтегрованих Si/AIIIBV RGB-джерел світла. Проаналізовано вплив динаміки температурних змін на реверсивний режим включення сві-тлодіодів як фотоприймачів у інтегрованих Si/AIIIBV RGB-джерелах світла. Досліджено вплив тем-пературної динаміки на довжину хвилі, інтенсивність випромінювання та колірну температуру досліджуваних зразків. Досліджено силу світла діодних джерел видимого випромінювання залеж-но від температури. Обґрунтовано необхідність використання при реалізації Si/AIIIBV RGB-джерел світла декількох світлодіодів у рознесені в часі моменти в реверсивному режимі включення. Табл.: 2. Іл.: 3. Бібліогр.: 13 найм.

Temperature changes of selected body’s surfaces of handball players in the course of training estimated by thermovision, and the study of the impact of physiological and morphological factors on the skin temperature

1. The aim of this study was to assess the temperature changes in the selected body surfaces (upper extremities—arm and forearm) in response to directed 90 min physical exercise as well as to analyse the impact of physiological and morphological factors on the dynamics of temperature changes. 2. The examined group consists of 16 professional handball players, submitted to an endurance training which lasted 90 min and contained elements of the actual game in a sports hall with air temperature of 20 °C and air humidity of 55%. 3. The mean temperatures from chosen body surfaces were registered before, immediately after and 10 min after physical effort (90 min) in comfort temperature conditions by means of a thermoviosion (ThermaCAM TM Sc500 camera). 4. Statistically significant positive correlation between maximum oxygen uptake (VO 2max), %HR max during the training session and the decrease in skin temperatures after exercise were observed.

Thermal characterisation of Lake Morskie Oko water in 2007 based on measurements by a gradient thermal probe

Thermal characterisation of Lake Morskie Oko water in 2007 based on measurements by a gradient thermal probeThe study was undertaken to illustrate a wide range of application of a gradient thermal probe in thermal characterisation of water reservoirs on the example of Lake Morskie Oko whose water temperature has been measured since 2006. For analysis, the data collected in 2007 were chosen because of the least missing data; in this year only the data from 13 days were not recorded. The data permitted analysis of changes in daily mean temperatures of water at particular depths, with the daily means calculated as arithmetic means from 144 measurements made at every 10 minutes. The daily amplitudes of temperatures at particular depths and mean daily amplitudes for particular months were determined, which permitted an assessment of the scale of the temperature amplitude damping with increasing depth. High frequency of temperature reading permitted detection of short-duration anomalies, taking place e.g. over a time span of 10 minutes, or their vertical extent. It has been established that measurement at 2 a.m. is the optimum for determination of the annual mean temperature. The time moments at which the minimum and maximum temperatures are recorded within a day at the surface were identified. Different variants of temporary jump changes in the surface water temperature within the day were analysed. The dynamics of temperature changes from the surface to the bottom of the lake was discussed.

Simulation of a solid-state cooler with electrocaloric elements

The dynamics of change in temperature at the edges of a layered structure consisting of one or more electrocaloric and heat-conducting elements in response to pulses of a periodic electric field has been studied with the use of the finite-element method. The possibility of using ceramic materials and (Ba,Sr)TiO3 films as electrocaloric and heat-conducting elements of linear and radial cooling structures is considered. The difference between the temperatures at the center and periphery of the radial film microstructure with two interdigital circular electrode lines is 2.5 K. An increase in the number of lines and the electric field frequency leads to an increase of the thermal effect.