Results For Temperature Change Research Articles

Projection of future long-term Aurelia coerulea biomass variability by regional moderate-temperature-duration approach in the Bohai and Yellow Seas

As temperature is regarded as a significant environmental factor affecting the intensity and frequency of jellyfish blooms, the projection of jellyfish peak biomass variation under global warming becomes essential for disaster prevention and mitigation on long-term time scales. The jellyfish Aurelia coerulea is distributed in worldwide oceans, particularly in the Bohai and Yellow Seas (BYSs), which are productive regions with substantial economic and climatic significance and have been suffered from A. coerulea blooms. Based on the theory of how A. coerulea reacts to various experimental temperature circumstances, recent studies have been proposed to determine the qualitative trends of A. coerulea blooms in response to climate change. However, the quantitative study of future A. coerulea biomass variability is a challenging task due to the uncertainty in the numerical relation between temperature and the biomasses of A. coerulea and the difficulty in determining the biomass considering the high mobility of jellyfishes. In this paper, we develop a moderate-temperature-duration approach to solve these two problems. The temperature suitability for all key life stages of A. coerulea during pelagic and benthic processes is involved in this approach, and we identify the major life stage that determines the peak biomass variation. The projection of future peak biomass of A. coerulea in BYSs is performed based on this approach and utilizing the long-term projection results of temperature changes by 2100 using the MPI-ESM-MR model from phase 5 of the Coupled Model Intercomparison Project (CMIP5) under the RCP4.5 scenario. The results indicate that global warming can certainly lead to the increase in A. coerulea biomass in some degree. The steady state of the highest peak biomass will be achieved during 2075∼2080, with an increase of 8.4%, 5.0%, and 11.5% in the Bohai Sea, the North Yellow Sea, and the South Yellow Sea, respectively, compared to the first steady state starting in 2020 detected by the regime shift. However, the result also shows that global warming cannot consistently lead to the increase of A. coerulea peak biomass. As the temperature rises to a large extent, the duration of moderate temperature ranges for strobilation and growth may be reduced, and thus resulting in the decrease of peak biomass instead.

Impact of the temperature factor on the quality of road clothes

The article deals with the problems of designing roads associated with short-term and relatively long-term rhythms of temperature fluctuations. The results of temperature changes in the long-term cycle in the Jizzakh region of Uzbekistan are presented. Based on the importance of the temperature factor, measures to prevent the process of destruction of asphalt concrete road surfaces are recommended.

Preliminary study of thermal density distribution and entropy analysis during cycling exercise stress test using infrared thermography

Considerable differences related to the results of temperature changes acquired during exercise exist, and in many cases, these lead to poor correlation with physiological variables. In this preliminary study we investigated the temperature changes and the temperature distribution (entropy) of the torso during a graded cycling exercise stress test using thermal imaging and studied the correlation between the increase in pulmonary ventilation (VE) and the changes in the surface temperature of the anterior torso during exercise. Thermal images of the anterior torso were captured every 30 s during the exercise, while the resistance was gradually increased every minute until exhaustion. The thermal images were processed to obtain a mean temperature in the regions of interest (ROI) (chest, forehead, and abdomen). We also developed an algorithm to calculate the distribution of temperature and texture (entropy) within each ROI. No changes were found in absolute temperatures. However, the entropy of the chest surface area increased significantly throughout the exercise test, compared with baseline temperature at rest. This increase in entropy was significantly correlated with exercise duration and intensity (p < 0.001). Furthermore, a high correlation between the increase in VE and chest entropy during exercise was detected (r = 0.9515). No correlations were found between the increase in entropy and the abdomen or the forehead compared with the VE. The non-invasive IR thermal imaging during graded exercise, combined with advanced image processing, successfully correlates surface thermography with exercise duration and pulmonary ventilation.

Effect of time, temperature and composition on the performance of conductive adhesives made of silver-coated copper powder

The effects of temperature and time (200, 250 and 300 °C for 15 h in total) on the electrical resistivity and phases of conductive adhesives were studied. Also, the effect of filler content (70 to 85 wt%) and graphite addition (2 to 15 wt%) on the performance of conductive adhesives in terms of electrical resistivity were investigated. These adhesives were prepared from Cu@Ag particles containing 20 and 50 wt% of silver. Two-point conductivity measurements, SEM, XRD, and TG/DSC analyses were used to evaluate the properties of the adhesives. The results showed that at a constant filler content, the electrical resistivity of adhesives prepared from powder containing 20 wt% silver increases with exposure time. However, the majority of the adhesives prepared from powder containing 50 wt% of silver under similar oxidation conditions had almost constant electrical resistivity. Moreover, the results of temperature change on the electrical resistivity showed that the electrical resistivity of adhesives prepared from powder containing 20 wt% of silver increases with temperature, although this increase was noticeable in some samples and negligible in the others. In contrast, an increase in temperature had very little effect on the electrical resistivity of most adhesives made from powders containing 50 wt% silver. The study of the effect of silver content in particles showed that adhesives prepared with filler containing 50 wt% of silver had significantly less electrical resistivity than adhesives prepared with filler containing 20 wt% of silver at all three temperatures. According to the XRD results, the formation of copper (II) oxide and its detrimental effect on electrical conductivity was the main reason of electrical conductivity reduction of adhesives. Graphite addition to an adhesive formula showed that the presence of graphite in appropriate amounts can prevent the oxidation of copper. Adhesives containing graphite after exposure at three temperatures in total for 15 h had electrical resistivities less than 0.028 Ω cm, while graphite-free adhesives under the same conditions had electrical resistivities of less than 0.072 Ω cm.

Influence of cocoon wrapping agrotechnics on the quality of cocoons

In addition to heredity, the biological and especially technological properties of cocoons are greatly influenced by the conditions of cocoon wrapping - temperature, humidity, light, ventilation (aeration), the quantity and quality of cocoons.As a result of temperature changes during cocoon wrapping, the speed and nature of the silkworm wrapping the silk fibers into the cocoon shell of the worm also change.

Investigation of the effect of ion transition type on performance in solid oxide fuel cells fueled hydrogen and coal gas

Renewable energy will be a panacea for environmental difficulties due to the extensive usage of carbon-rich fuels as a main source of energy. As a result, hydrogen-fueled solid oxide fuel cell is a revolutionary clean technology that has a great contribution in solving the current energy and environmental-related challenges. Thus, a 3D model of hydrogen and coal gases fueled solid oxide fuel cell (H2–SOFC) using different electrolytes has been developed and simulated using COMSOL commercial software to explore the performance of electrolyte supported SOFC. The performance of the developed model has been studied and characterized using different differential equations. Accordingly, it has been found that the performance of hydrogen-fueled oxide ion conducting electrolytes (SOFC–O) is lower than that of protonic conducting one (SOFC–H) at 800 °C. Furthermore, a numerical simulation has been conducted to investigate the result of temperature changes on SOFC performance at 400 °C, 600 °C, and 800 °C for proton-conducting SOFC and 800 °C and 1000 °C for oxygen-conducting SOFC. It has been demonstrated that SOFC–O shows a better performance at high temperatures compared with SOFC–H while SOFC–H can be an agreeable selection at medium temperatures. Therefore, this study reveals that the temperature augments the performance of both electrolytes, yet at higher working temperatures SOFC–H becomes more advantageous than SOFC–O to use hydrogen and coal gas as a primary fuel. Besides, the effect of channel height was also analyzed numerically and the finding disclosed that decreasing the channel height emerges in a curtly current path. Thus, it can be reasoned out that the performance of SOFC decreases when the channel height is increased.

Utilization of bus tree wood (Melaleuca sp) as environmentally friendly fuel for household industrial scale Aluminum smelting stoves in Merauke, Papua

The purpose of this study is the use of bus wood trees as fuel for aluminum smelting for the home industry because it has a good heating value and is very efficient, from the laboratory test results, the bus tree wood has a calorific value of 5981 (calories/g). The methods used experimental and analytical to get the results from the use of bus wood as fuel for aluminum smelting which will certainly produce good mechanical properties. The results obtained a good combustion process that releasing all the heat contained in a fuel and done with three combustion control processes, including a fairly high temperature to ignite and maintain the flame of the fuel, turbulence or mixing O2 and the use of good fuel and sufficient time to complete combustion process. The fuel (bus wood) which is inputted in the furnace is designed so that the combustion process takes place more completely with minimal heat losses. The results of temperature changes seem a thermocouple and crucible furnace insulator material were very good heat resistance hence the time of the melting process it doesn't take longer which is 15 minutes. The aluminum in crucibles has melted at a temperature of 723℃.

ВИЗНАЧЕННЯ ГРАНИЧНО ДОПУСТИМИХ ШВИДКОСТЕЙ ОХОЛОДЖЕННЯ ОБОДУ ЗАЛІЗНИЧНИХ КОЛІС ДЛЯ ФОРМУВАННЯ ОДНОРІДНОЇ СТРУКТУРИ

Compliance with the new more stringent requirements for railway wheels is possible only with an integrated approach to improving their production technology with a reasonable choice of heat treatment modes, taking into account the chemical composition of steel. The purpose of the study is the experimental and analytical determination of the maximum permissible cooling rate of the rolling surface and the minimum required cooling rate of the central sections of the rim of a railway wheel to achieve a high level of hardness of the ferrite-pearlite structure. The studies were carried out on steels of grades ER8 and ER7 according to EN 13262, grade 2 according to GOST 10791: 2016, steel of class C according to AAR M-107 / M-208. Based on the hardenability test (GOST 5657) by the end hardening method (according to the Jomeni method), the distance from the surface from which one-sided cooling was performed, where the hardness met the requirements of the normative documentation for wheels made of the steel under study, the distance where the formation of needle-like structures did not occur, was determined, including bainite and widmanstatt according to the results of metallographic studies and determination of hardness. Based on the results of temperature changes during the cooling process, the cooling rates were determined in places that met the specified conditions. In the work, modeling was applied in the QForm VX 8.2 software package, as a result, a model was developed for the adaptation of which the results of the experiment were used. The high convergence of the results of calculation and experiment was confirmed. At the same time, the model made it possible to obtain the instantaneous cooling rate in a form that is more consistent with the physical meaning of the process and to avoid the scatter of actual values associated with the discreteness of data recording. It was found that the instantaneous cooling rate changes during the continuous uniform supply of the coolant. In some cases, a significant slowdown in cooling was recorded, or even negative values of the instantaneous cooling rate. This is due to the release of the heat of phase transformation, which occurs during the decomposition of austenite by the diffusion mechanism. The developed model can be used to construct thermokinetic diagrams during continuous cooling and to develop recommendations for heat treatment modes to achieve the specified mechanical properties at a certain structural state.

Impact Of Aerobic Biostabilisation And Biodrying Process Of Municipal Solid Waste On Minimisation Of Waste Deposited In Landfills

Abstract The article discusses an innovative system used for aerobic biostabilisation and biological drying of solid municipal waste. A mechanical–biological process (MBT) of municipal solid waste (MSW) treatment were carried out and monitored in 5 bioreactors. A two-stage biological treatment process has been used in the investigation. In the first step an undersize fraction was subjected to the biological stabilisation for a period of 14 days as a result of which there was a decrease of loss on ignition, but not sufficient to fulfill the requirements of MBT technology. In the second stage of a biological treatment has been applied 7-days intensive bio-drying of MSW using sustained high temperatures in bioreactor. The article presents the results of the chemical composition analysis of the undersize fraction and waste after biological drying, and also the results of temperature changes, pH ratio, loss on ignition, moisture content, combustible and volatile matter content, heat of combustion and calorific value of wastes. The mass balance of the MBT of MSW with using the innovative aeration system showed that only 14.5% of waste need to be landfilled, 61.5% could be used for thermal treatment, and nearly 19% being lost in the process as CO2 and H2O.

AN INVERSE MATHEMATICAL APPROACH FOR THERMAL STRESSES IN A SOLID SPHERE

The present work deals with the determination of unknown temperature and thermal stresses in a solid sphere. A solid sphere is subjected to arbitrary known interior temperature under steady state. The Legendre's transform are used for heat transfer analysis to determine temperature change within solid sphere. The solution of Navier's equation in terms of Goodier's thermoelastic displacement potential and the Boussinesq's harmonic function for spherical co-ordinate system have been used for thermal stress analysis. The results for temperature change, displacement and stresses have been computed numerically and illustrated graphically.

Three Dimensional Steady State Thermal Stress Analyses in a Clamped Solid Sphere

The present work deals with the three dimensional axisymmetric problem in a spherical coordinate system. A clamped solid sphere is subjected to heat flux on its plane boundary surface. Heat is generated within the sphere. The attempt made to analyze heat transfer and thermal stresses of solid sphere under steady temperature field. The Legendre's transforms are used for the solution of governing heat conduction equation. The solution of Navier's equation in terms of Goodier's thermoelastic displacement potential and the Boussinesq's harmonic function for spherical co-ordinate system have been used to determine displacement and thermal stresses within solid. The results for temperature change, displacement and stresses have been computed numerically and illustrated graphically.

Termički efekti mobilnih telefona - nova merenja

Heating of the mobile phones presents consequence of their usage. Thermal effects are presented through SAR (Specific Absorption Rate) and increasing of temperature of exposed part of body (tissue), so it is necessary to detect and measure these values. Thermal effects could be detected with special devices, such as thermal camera or IC thermometer. New versions of mobile phones present multimedia devices with lot of different functions and possibilities. All that tasks demand great waste of energy. After confirmed facts that the time of usage of mobile phones constantly increases, there is a question does this usage increase the mobile phone temperature and, on that way, present the danger to their user. This work gives results of temperature changes of ten different mobile phones for different usage purposes, such as temperature changes of head region while and after mobile phone usage.

Effect of Michell function on the thickness of circular plate with internal heat generation

The present paper deals with the determination of displacement and thermal transient stresses in a thick ( ) circular plate with internal heat generation. External arbitrary heat supply is applied at the upper surface of a thick ( ) circular plate, whereas the lower surface of a thick ( ) circular plate is insulated and the heat is dissipated due to convection in surrounding through lateral surface. Here we compute the effect of Michell function on the thickness of circular plate with internal heat generation. The governing heat conduction equation has been solved by using integral transform method and the results are obtained in series form in terms of Bessel's functions and the results for temp erature change and stresses have been computed numerically and illustrated graphically. Keywords:Thick plate ( ) Thin plate ( ) , internal heat generation, thermal stresses.

Transient Thermoelastic Analysis of a Laminated Hollow Cylinder Constructed of Isotropic Elastic and Magneto-Electro-Thermoelastic Materials

This paper presents the theoretical analysis of a laminated hollow cylinder constructed of isotropic elastic and magneto- electro-thermoelastic materials under unsteady and uniform surface heating. We obtain the exact solution of the transient thermoelastic problem of the laminated hollow cylinder in the plane strain state. As an illustration, we perform numerical calculations of a three-layered composite hollow cylinder made of isotropic elastic, piezoelectric and magnetostrictive materials and investigate the numerical results for temperature change, displacement, stress, and electric and magnetic potential distributions in the transient state.

Heat Transfar and Thermal Stress Analysis In Annular Cylinder under Steady State

The present manuscript deals with the heat transfer and thermal stress analysis of thick annular cylinder under steady temperature conditions. A annular cylinder is subjected to arbitrary heat flux applied on the upper surface with lower surface is thermally insulated. The fixed circular edges are at zero temperature. The integral transform methods are used for heat transfer analysis to determine temperature change. The theory of linearized thermoelasticity based on solution of Naviers equation in terms of Goodiers thermoelastic displacement potential, Michell's function, and the Boussinesq's function for cylindrical co-ordinate system have been used for thermal stress anaylsis. The results for temperature change, displacement and stresses have been computed numerically and illustrated graphically.

Some study of Thermoelastic Steady State behavior of Thick annular disc with Internal Heat Generation

The present paper deals with the determination of displacement and thermal stresses in a thick annular disc with internal heat generation. Arbitrary heat �� �� is applied on the upper surface of disc whereas lower surface dissipates heat by convection and the fixed circular edge are thermally insulated. Here we compute the effects of internal heat generation of a thick annular disc in terms of stresses along radial direction. The governing heat conduction equation has been solved by the method of integral transform technique. The results are obtained in a series form in terms of Bessel's functions. The results for temperature change, displacement and stresses have been computed numerically and illustrated graphically.

Effect of Michell Function on Steady State Behavior of Thick Circular Plate with Internal Heat Generation

The present paper deals with the determination of displacement and thermal stresses in a thick M ≠ 0 circular plate under steady temperature field. Arbitrary heat flux is applied at the upper surface of a thick M ≠ 0 circular plate, whereas lower surface at zero temperature and the fixed circular edge is thermally insulated. Here we compute the effects of Michell function on the thickness of circular plate with internal heat generation. The governing heat conduction equation has been solved by the method of integral transform technique. The results are obtained in a series form in terms of Bessel’s functions. The results for temperature change, displacement and stresses have been computed numerically and illustrated graphically.

Nonhomogeneous Heat Conduction Problem and Its Thermal Deflection Due to Internal Heat Generation in a Thin Hollow Circular Disk

This article is concerned with the determination of temperature and thermal deflection in a thin hollow circular disk under an unsteady-state temperature field due to internal heat generation within it. Initially, the disk is kept at an arbitrary temperature F(r, z). For times t > 0 heat is generated within the thin hollow circular disk at a rate of g(r, z, t) Btu/hr ft3, while the boundary surfaces at (r = a), (r = b), (z = 0) and (z = h) are kept at temperatures f 1(z, t) and f 2(z, t), f 3(r, t) and f 4(r, t), respectively. The governing heat conduction equation has been solved by using a finite Hankel transform and the generalized finite Fourier transform. The results are obtained in series form in terms of Bessel's functions. As a special case, different metallic disks have been considered. The results for temperature change and the thermal deflection have been computed numerically and illustrated graphically.

Species composition, abundance and biomass of Copepoda in plankton of the northern Levantine Basin (eastern Mediterranean)

Changes in species composition, abundance and biomass of copepods were monitored weekly over the year 1998 in shelf waters of the northern Levantine Basin. A total of 192 copepod species belonging to 61 genera were identified during the course of this study. Thirty-six species are reported for the first time from the region, including three new species. Copepod abundance ranged from 215 individuals m−3 in early March to 2220 individuals m−3 in late March, whereas the biomass ranged from 4 mg m−3 in mid-January to 22 mg m−3 in mid-February. The copepod fauna was found to be most species-rich on 4 November (Margalef’s Index d = 7 . 4 ) and least on 10 March ( d = 3 . 3 ). The index was found low during spring and autumn with lowest levels obtained during the stratification period from September to October. The diversity was found to be highest on 18 February (Shannon-Wiener Index H ′ = 2 . 9 ) and lowest on 31 March ( H ′ = 1 . 6 ). Higher index values were characteristic of the winter period. A proportional representation of the species among their populations was well established during February whereas the best situation was met on 3 March and the most unbalanced situation at the end of March. Multivariate analyses have shown the formation of distinct seasonal communities of copepod species throughout the year. The observed seasonality in community structure is suggested to be a result of wide range changes in temperature throughout the year. The dominant species observed during late winter and spring were Oithona nana, Oithona sp., Oncaea media, Oncaea sp., Calocalanus elegans, Euterpina acutifrons and Oncaea zernovi, respectively. Calocalanus sp., C. elegans, Triconia dentipes, Oncaea sp., Oithona nana, Clausocalanus furcatus, and Temora stylifera were dominant during summer, whereas Oncaea sp., Calocalanus sp., Oithona nana, Clausocalanus paululus, C. furcatus, Parvocalanus sp., and Calocalanus elegans dominated the autumn and early winter populations. Sharing similar species with the Indo-Pacific region gives the copepod fauna of the Levantine Basin, at least in part, a subtropical affinity.

Prediction of bulk modulus and volumetric expansion coefficient of water for leak tightness test of pipelines

To determine whether any pressure variation in pipeline hydrostatic test is a result of temperature changes or the presence of leaks, the calculation of pressure/temperature changes is required for test sections. In these calculations, bulk modulus and volumetric expansion coefficient of fresh or sea water must be taken into account. In this study, a simple-to-use correlation is developed to predict the bulk modulus and volumetric expansion coefficient of both fresh and sea water as a function of temperature and pressure. The proposed correlation helps to cover the bulk modulus and volumetric expansion coefficient of both fresh and sea water for temperatures less than 50 °C (40 °C for sea water) as well as pressures up to 55,000 kPa (550 bar). The results can be used in follow-up calculations to determine whether any pressure variation in pipeline hydrostatic test is a result of temperature changes or the presence of leaks. The proposed correlation showed promising results with average absolute deviations for volumetric expansion coefficient and bulk modulus of water being around 0.58% and 0.08% respectively. The novel correlation is easy to use and will prove to be of immense value for project engineers to test the critical limits accurately.