Average Temperature Distribution Research Articles

Changing climatic indicators and mapping of soil temperature using Landsat data in the Yangan-Tau UNESCO global geopark

Changes in key climate index affect ecosystems and biodiversity. In this regard, the assessment of the climatic conditions is of particular relevance. This study presents the results of an analysis of climate change and digital mapping of soil temperature in the Yangan-Tau UNESCO Global Geopark (Russia). The steady increase in air temperature was revealed, which causes an increase in the sum of active temperatures and the duration of the warm period of the year. Annual total precipitation during 1966-2020 changed the sign of the trend: positive trend (increase in precipitation) in 1966-1990, while in 1991-2020 is negative. The hydrothermal indicators determined the increase in aridity during the warm period. Based on the analysis of changes in the climatic conditions of the geopark, a comparison was made of the temperature regimes of air and soil, and the relationship between these indicators in the snow-free period was revealed (R2 = 0.62). An approach is presented for digital mapping of the temperature regime of the surface layer of soils based on ground-based research data and the results of interpretation of the Landsat thermal bands. A significant relationship between soil temperature and Earth surface temperature for the snow-free period was revealed (R2 = 0.83). Based on the obtained regression model and Landsat 8-9 data for the snow-free period of 2013-2022 the map of the distribution of average temperatures of the surface layer of soil from May to October was produced, which clearly demonstrated the relationship between soil temperature and biomes. Keywords: soil temperature; surface land temperature; remote methods; climate change; Yangan-Tau UNESCO global geopark; Bashkortostan.

STUDY OF THE TEMPERATURE DISTRIBUTION IN A PARABOLIC CYLINDRICAL CONCENTRATORUSING A NANOFLUID AS HEAT TRANSFER FLUID

We have numerically studied the heat transfers in a Cylindrical-parabolic concentrator using a nanofluid as heat transfer fluid for its use in Solar Thermodynamics. After an analysis of the work relating to solar concentrators and nanofluids, we have, after having described our physical system and posed working hypotheses, written the equations which govern the transfers in our collector. The latter as well as the associated boundary conditions were then dimensionless in order to generalize the problem and reveal the parameters that control the operation of the absorber. To solve our equations, we used the method of finite differences and the algebraic system obtained is solved thanks to the Thomas method combined with an iterative process of line-by-line relaxation type. The computer code that we developed made it possible to find the temperature distributions according to the spatial coordinates and at different times. The effects and influences of wind effect, axial and transverse thermal dispersion, absorber length, geometric shape factor on the average temperature distributions of the coolant is analyzed. At the end of the study, we were able to identify the most important physical and geometric parameters which give our system optimum operation for its use in Solar Thermodynamics.

Climate of the Pokuttia and Bukovyna Carpathians and foreland in the second half of the 19th – at the beginning of 20th centuries

Climate reconstruction of the Pokuttia and Bukovyna Carpathians, its foreland and adjacent mountain and foothill areas in the 19th century is performed due to a dense network of meteorological observations, starting from the 60s of the 19th century in the Bukovyna and Galychyna provinces within the Austrian Monarchy and several paleoclimatic reconstructions, mainly dendroclimatic, carried out on the basis of data collected in the Eastern Carpathians. Spatial interpolations using universal kriging has been performed based on in-situ homogenized data of weather stations of the second half of the 19th century – the first half of the 20th century. The longest series of observations in the city of Chernivtsi since 1852 has enabled to track multidecadal changes in average annual and monthly air temperatures and atmospheric precipitation. The centennial course of these climatic indicators corresponds to the general patterns characteristic of all the Eastern Carpathians with the most pronounced continentality among the rest of the Carpathian regions. Cold decades in the second half of the 19th century in Chernivtsi are considered the continuation of the coldest period of 1720–1850 in the Eastern Carpathians in the last 600 years. The spatial distribution peculiarities of average monthly temperatures in the second half of the 19th – at the beginning of 20th centuries in the region are manifested in a pronounced orographic steplike isotherm pattern. In the second half of the 19th century – the first half of the 20th century, the average long-term temperatures ranged from +3.5 to +4 °C in the southwest to +8 °C in the north and northeast in accordance to the orientation of the mountains. Inversion features of the valleys and internal lowlands are revealed in the spatial distribution of average temperatures, especially in the summer months. These features are also distinguished by a lower amount of atmospheric precipitation in the dry months of spring and autumn. Spatial distribution of temperature and precipitation in the second half of the 19th century – at the beginning of 20th century is also distinctive in the the inner mountain ridges of the adjacent Hryniava and Chornyi Dil mountains. These mountains are founded to be the coldest, often with a lack of meteorological summer and a maximum of precipitation in the spring and autumn months. A comparative analysis of the spatio-temporal distribution of average multi-year air temperatures and precipitation at the turn of the 19th and 20th centuries was performed. In general, similar distribution of air temperatures and precipitation is revealed. The differences are more noticeable in the monthly context, especially in summer and in the mountainous parts of the region. Comparing the turns of 19th and 20th centuries, the average July monthly temperature in the southernmost mountain massifs of the region has increased by 1 °C, while in the foothills the increase does not exceed 0.5 °C. In the annual context, changes are less noticeable. The range of air temperature changes from north to south is the same at the turn of both the 19th and 20th centuries. The city of Chernivtsi is founded to become a bit warmer (by 0.5 °C), but interannual fluctuations of annual air temperatures within 2 °C are typical throughout all the centuries. Alongside, high annual temperatures (+9 °C and higher) have been observed more often. While in the last century such temperatures were recorded once per 5–10 years, in the first decade of this century, annual temperature above +9 °C is recorded every second year. Short-term fluctuations (5–10 years) of annual precipitation amounts have been characteristic of the whole period since the 19th century. The interpretation of local climatic differences involves further devolopment of accurate interpolation techniques and downscaling, especially for the construction of precipitation field given lack of high-mountain weather stations in the earlier centuries. The latter corresponds to the future studies of the author.

Pore-scale direct numerical simulation of fluid dynamics, conduction and convection heat transfer in open-cell Voronoi porous foams

The pore-scale analysis includes the pore network simulation and direct numerical simulation, which the latter is more accurate and provides more details about the problem. This study presents a pore-scale direct numerical simulation of flow and convection-conduction heat transfer in open-cell metal foams with a complex structure. First, using the Laguerre–Voronoi tessellations (LVT) algorithm, three foam samples with various porosities (76.6%, 84.4%, and 93.8%) and a constant pore density of 20 pores per inch (PPI) are generated. Next, the open-source library of OpenFOAM is employed to perform heat transfer and flow analysis in Darcy and non-Darcy regimes. Results were verified through comparison with available experimental and numerical data. The effects of foams' porosity, solid material, and Reynolds number on flow characteristics and heat transfer are investigated. Results are presented in terms of the permeability, Forchheimer coefficient, the volumetric and average heat transfer coefficient, and temperature and velocity distribution. By decreasing porosity, the flow complexity increases with subsequent increments in heat transfer and pressure drop. Also, the conductive heat transfer through the foam plays a vital role in the total heat transfer rate. These pore-scale outcomes could be used in macro-scale thermo-fluid models to perform more accurate simulations with less computational costs.

Online in-situ monitoring of melt pool characteristic based on a single high-speed camera in laser powder bed fusion process

• A coaxial melt pool temperature measurement system with a single high-speed camera in the LPBF process is developed. • A dual-waveband image-matching method with sub-pixel accuracy, and an overall parameter calibration and optimization method are proposed. • The melt pool characteristics including the temperature distribution, profile, temperature gradient, and cooling rate are measured by the developed system, and the distribution of average temperature and peak temperature under different linear energy densities during single-line printing is compared and analyzed. In metal additive manufacturing (AM), the in-situ measurement of the melt pool characteristic plays a significant role in monitoring the quality of the printed components. In this work, based on dual-wavelength thermometry, a coaxial melt pool temperature measurement system with a single high-speed camera in the laser powder bed fusion (LPBF) process is developed, including the design of the relay and optical path amplification system, and the beam splitting and chromatic aberration correction system. Moreover, a dual-waveband image-matching method with sub-pixel accuracy, and an overall parameter calibration and optimization method are proposed to improve the accuracy of the coaxial temperature measurement system. Besides, the validation experiment measured by a high-temperature blackbody furnace and a standard photoelectric pyrometer indicates that the temperature measuring error of the developed system is less than 1%. The melt pool characteristics including the temperature distribution, profile, temperature gradient, and cooling rate were measured by the developed coaxial temperature measurement system, and the distribution of average temperature and peak temperature under different linear energy densities during single-line printing was also compared and analyzed. The single-line printing results of different parameters show that the higher the linear energy density, the higher the average temperature and peak temperature of the melt pool, and the optimized parameters minimize the fluctuation of melt pool temperature and are more favorable to the formation of high-quality parts. In multi-layer printing mode, the heat accumulation is strong, resulting in the slow cooling rate of the melt pool.

Numerical analogy of bioheat transfer and microwave cancer therapy for liver tissue

AbstractA numerical study of microwave cancer therapy for cylindrical‐shaped liver tissue with an elliptical‐shaped liver tumor has been carried out by this study. The time‐dependent electromagnetic wave and the bio‐heat transfer equations have been used as the governing equations and solved with appropriate boundary conditions using Galerkin's weighted residual scheme built‐in finite element method‐based COMSOL Multiphysics software. The coaxial applicator as well as the effects of different microwave input power levels (from 5 to 25 W), frequencies (from 0.7 to 5 GHz), and treatment time (from 0 to 1000 s) on hepatocellular carcinoma have been examined by this simulation and displayed graphically in terms of the microwave power dissipation, isothermal lines inside liver tissue, time‐dependent profiles of temperature at different locations inside the tumor, specific absorption rate (SAR), and surface average transient temperature distribution of tumor tissue. The results demonstrate that microwave input antenna power and frequency have significant impacts on the temperature distribution and SAR values of liver tissue. When the microwave input power, as well as frequency, is increased, SAR and tissue temperature values also increase but the high temperature is harmful to healthy tissue. It is observed from the performed analysis that the mean temperature of the tumor cell is about 56.86°C at a time of 180 s using 10 W microwave input power and 2.45 GHz frequency.

Numerical simulation of sodium mist behavior in turbulent Rayleigh-Bénard convection using new developed mist models

In order to evaluate the mist behavior in the cover gas region of Sodium-cooled Fast Reactors (SFRs) in good accuracy, turbulent model for Rayleigh-Bénard convection (RBC) was selected, and the Reynolds-averaged number density and momentum equations for mist behavior were developed and incorporated into the OpenFOAM code. In the first stage, the RBC in a simple parallel channel was calculated using Favre-averaged k-ω SST model. The average temperature and flow characteristics agreed well with results from DNS, LES, and experiments. Then the basic heat transfer experiment simulating the cover gas region of SFRs was calculated using this turbulent model and new mist models. The calculated average temperature distribution in the height direction and the mist mass concentration agreed well with the experimental results. We developed a method that could simulate the mist behavior in turbulent RBC environments and the cover gas region of SFRs with high accuracy.

Experimental Study on Manned/Unmanned Thermal Environment in Radar Electronic Shelter Based on Different Air Supply Conditions

Studies on the thermal environment of the electronic radar shelter have been mainly focused on the simulation of the unmanned thermal environment, and there have been few studies on experiments in the thermal environment. Additionally, a comparative study of the experimental results from manned and unmanned shelters has been missing. In this paper, we experimented in thermal environments of manned/unmanned shelter under different air supply conditions. The experiment was divided into cooled, ventilated, and heated trials analyzing three aspects: (1) The average temperature distributions of walls, air inlet points, air outlet points, and surfaces were measured over time under different conditions in an unmanned shelter. The temperature distribution curve was fitted into the function. (2) Based on different working conditions, the temperature distribution experiments were carried out in three different areas for subjects wearing short or long clothing respectively. (3) The wind speed was measured at each measuring point in the air supply pipeline under different working conditions. The wind speed distribution was detected on the setting surfaces. The experimental results show that: (1) The air does not gradually tend to steady state with the time, and under different conditions, the air temperature obviously differs. (2) The clothing selection, air supply conditions, and locations of measuring points have significant influences on human body temperature distribution and left–right difference. (3) The mixing of the thermal plume caused by the vertical temperature difference of the human body and the jet generated by the mechanical air supply will reduce the wind speed of the airflow in the cabin, the adsorption of the jet to the bulkhead, and the stability of the airflow. The experimental data can provide the initial and boundary conditions for the simulation of the shelter. The results can provide a reference for the study of fluid control methods, the setting of thermal boundary conditions, and the simulation of the influence of thermal plumes on the airflow distribution. The experimental study in this paper has filled in the blanks regarding experimental study in electronic radar shelters. It has important research value and practical significance.

Integrating Taguchi Method and Gray Relational Analysis for Auto Locks by Using Multiobjective Design in Computer-Aided Engineering

In automobiles, lock parts are matched with inserts, and this is a crucial quality standard for the dimensional accuracy of the molding. This study employed moldflow analysis to explore the influence of various injection molding process parameters on the warpage deformation. Deformation of the plastic part is caused by the nonuniform product temperature distribution in the manufacturing process. Furthermore, improper parameter design leads to substantial warpage and deformation. The Taguchi robust design method and gray correlation analysis were used to optimize the process parameters. Multiobjective quality analysis was performed for achieving a uniform temperature distribution and reducing the warpage deformation to obtain the optimal injection molding process parameters. Subsequently, three water cooling system designs—original cooling, U-shaped cooling, and conformal cooling—were tested to modify the temperature distribution and reduce the warpage. Taguchi gray correlation analysis revealed that the main influencing parameter was the mold temperature followed by the holding pressure. Moreover, the results indicated that the conformal cooling system improved the average temperature distribution.

СРАВНЕНИЕ МНОГОЛЕТНИХ МЕТЕОРОЛОГИЧЕСКИХ ХАРАКТЕРИСТИК ПО ДАННЫМ РЕАНАЛИЗА И НАЗЕМНЫХ НАБЛЮДЕНИЙ НА ТЕРРИТОРИИ МОСКОВСКОЙ ОБЛАСТИ

Purpose: to carry out a comparative analysis of meteorological characteristics (average monthly precipitation and average monthly air temperature) on Moscow region territory based on the ERA5-Land Copernicus (C3S) reanalysis data and stationary weather stations. Materials and methods. Data obtained from 11 weather stations located in different districts of Moscow region from April to September 2000–2020, as well as data from climate archives based on regular meteorological observations, aerologic and satellite information was used. A comparison of the average monthly air temperature and precipitation for the growing season of main agricultural crops was carried out, the data deviation based on the reanalysis results from the actual data was presented, the correlation coefficients were calculated, the result of calculating the Pearson correlation coefficient was presented, and the advantage of the reanalysis data was shown. Results: the calculations obtained showed that the distribution of average monthly temperature and precipitation differs slightly from the observation data, which can be explained by the peculiarities of determining the coordinates of the weather station relative to the reanalysis grid nodes. Conclusions. ERA5-Land reanalysis data are suitable for determining the main meteorological characteristics in those areas where there are no stationary weather stations or access to their data is difficult. The reanalysis values as a whole reflect the variability of air temperature and precipitation in the study area of Moscow region quite well relative to the indicators obtained by ground-based observations. ERA5-Land data can be supplemented and applied in various fields of research, such as climate forecasting, yield forecasting using agro-climatic indicators, irrigation or drainage planning, etc.

Measuring surface temperatures of different types of fly ash samples using a CCD camera

In this work, an optical emission-based two-color method was experimentally investigated for the measurement of surface temperatures of different types of fly ash samples using a CCD camera. A heating system consisting of a Hencken flat-flame burner, a narrow piece of stainless steel wire mesh to separate the flame and the ash samples to be studied, and a thermocouple to record the temperature, was used to heat fly ash samples. A color camera equipped with a tri-band filter was used to capture radiation images. Fly ash samples collected from three kinds of coal-fired boilers were heated and imaged at different temperatures. The chemical compositions, elements, and particle size distributions were analyzed. The emissivity ratios of the wavelengths corresponding to the R and G optical channels and permitted by the tri-band filter were experimentally determined. A two-color method was subsequently used to calculate the average surface temperatures with relative errors within ?2% in the experiments, and an uncertainty analysis was conducted. Surface temperature distributions were also calculated and presented. The results demonstrate that the emission-based two-color method can be used to determine reliable average surface temperatures and surface temperature distributions when the radiation emitted from the ash samples is obviously greater than the ambient light. The results also show that the method has a lower limit of temperature measurement, which will lessen with the use of larger apertures and a higher radiation capacity of the ash samples to be studied.

Распределение температурных показателей по профилю серогумусовой почвы, остров Западный Шпицберген

The air and profile of Umbrisols in the south-western part of Svalbard are characterized by negative average annual temperatures. The duration of the period with positive temperatures at the depth of the umbric horizon (8–10 cm) is 128 days; the sum of positive temperatures is about 500 оС. The distribution of average monthly temperatures in all horizons in the profile of 0–60 cm in the annual cycle reliably correlates with air temperature.

2018년 여름 집계구 단위의 상세 폭염취약성 원인 분석 : 구례군과 순창군을 대상으로

This study attempted to analyze the characteristics of heatwave damage in Gurye-gun and Sunchang-gun in 2018, at the height of a severe heatwave, and to identify detailed heatwave-vulnerable areas through spatial analysis. Data were assembled in units of aggregation zones for detailed spatial analysis. Shadow patterns, Sky view factor (SVF), and average radiation temperature distributions of 5m resolution were calculated using a solar radiation model for high-resolution thermal environment analysis. Individuals, environments, diseases, and weather factors that can affect heat wave damage were analyzed in units of census, and variables with spatial autocorrelation for Gurye-gun and Sunchang-gun were extracted through the model of Global Moran

Modelling and Comparison of the Thermohydraulic Performance with an Economical Evaluation for a Parabolic Trough Solar Collector Using Different Nanofluids

This study examines the three-dimensional heat transfer and flow characteristics of nanofluids in a parabolic trough solar collector under turbulent flow conditions, whereas a non-uniform focused heat flux was applied to the absorption pipe. CuO/water, Al2O3/water, TiO2/water, and SiO2/water are studied numerically. The dynamic and thermal fields are determined by the Reynolds number varying between 50000 ≤ Re ≤ 250000, while the volume concentration of nanofluids is the following: 3% CuO, 6% Al2O3, 4.82% SiO2 and 3.15% TiO2, the nanoparticle size of 30 nm by means of Finite Element Method (FEM). Effects of various parameters such as volume fraction of nanoparticles (φ), various Reynolds numbers and type of nanoparticle on thermo-hydraulic performance of the parabolic solar collector are studied. The average Nusselt number, heat transfer coefficient, average friction factor, pressure drop, temperature and velocity distribution are illustrated using four different types of nanofluids and four different volume fractions of nanoparticles with various Reynolds numbers. According to the final results, both TiO2 and CuO nanofluids have better performance in terms of thermal and hydraulic efficiency and evaluation economic performance compared with other nanofluids studied.

Thermal efficiency of eco-friendly MXene based nanofluid for performance enhancement of a pin-fin heat sink: Experimental and numerical analyses

MXenes are an eco-friendly innovative type of graphene-like nanomaterials and are proven to exhibit remarkable thermal, electrical, mechanical and optical properties. This study is aimed at evaluating the thermal efficiency of novel Ti3C2Tx MXene-based nanofluid in a pin-fin heat sink was via experimental and numerical analyses. The aqueous-based 2D Ti3C2Tx MXene nanofluid was synthesised in a two-step process, followed by their characterisation and experimental testing. For the numerical analysis, the forced convection of the nanofluid was simulated through multiphase Lagrangian–Eulerian approximation by incorporating the interphase interactions of Brownian motion, thermophoresis, drag and Saffman lift forces, gravity, virtual mass and pressure gradient-induced forces. The thermal performance of the MXene nanofluids was assessed in terms of log mean temperature difference, average Nusselt number, local temperature and local Nusselt number distribution at the base of the heat sink and thermal contours. Their fluid flow characteristics were probed by analysing the coolant pumping power, flow streamlines distribution and performance evaluation criteria of the heat sink. Results demonstrated that utilising the MXene-based coolant resulted in a significant average Nusselt number enhancement at the expense of a small increase in coolant pumping power. Maximum improvements of 29.8 and 40.5% in the average Nusselt number were observed for nanoparticle concentrations of 0.013 vol% and 0.027 vol% respectively.

Distributions of environmental parameters and fish at Humbold Bay, Jayapura

Research on the distribution of fish and plankton in waters that are equipped with environmental parameters is needed to obtain maximum results and increase accuracy also it provides comprehensive information. The research, which was conducted in Humbold Bay, aimed to map the fish and plankton distribution data both vertically and horizontally and combine it with environmental parameters in the bay. Fish and plankton’s data was the volume backscattering strength (Sv) value obtained using the SIMRAD EK-15 device while environmental parameter data, such as temperature, salinity, and chlorophyll obtained from marine.copernicus.eu which processed in the 5-80 m depth range. The results showed that Humbold Bay had the highest average surface temperature distribution was 30 °C, with the highest average salinity from 35.89 ppt and the highest average chlorophyll value from 0.3859 mg/m3. The horizontal distribution of plankton had an average SV value of -76.63 dB, while the fish was -56.00 dB that evenly distributed. Vertically, the Sv of plankton decreased with increasing depth as well as the Sv of fish which its’ also did not have a distribution pattern in certain environmental parameters.

Temperature distribution modeling of PV and cooling water PV/T collectors through thin and thick cooling cross-fined channel box

Many aspects relating to thermal, economic, and reliability challenges are involved while designing a Photovoltaic/Thermal (PV/T) system under high performance. When compared to standard PV systems, PV/T systems are more effective in locations with high irradiance. To eliminate the excess heat from a PVT system, an optimal cooling system is necessary, resulting in improved the temperature of PV module which directly effect on the overall performance. The current study is focused on a new economic and essay construction thin and thick (3 mm and 15 mm) cooling cross-fined channel box that have covered modeled. In terms of cell temperature and output cooling water temperature, the effects of various irradiation levels and cooling water flow rates are examined. Software that is based on finite elements, the problem was solved numerically in a three-dimensional model using ANSYS (19.2). It has been discovered that when the cooling fluid flow rate increases, the average surface temperature distribution of PV/T system and outlet cooling water temperature are reduced for thin and thick box heat exchanger and ideal with a cooling fluid flow rate of 3 L/min. The average surface temperature and water-cooling temperature are 30.7 °C and 38.9 °C for thin box heat exchanger, respectively, whereas for thick box heat exchanger are 30.8 °C and 32.4 °C, respectively, under solar irradiance 1000 W/m2 and optimal flow rate.

Non-isothermal vortex flow in the T-junction channel

In this work we present the numerical simulation of coolant mixing modes in the T-junction. We shows that the RANS approach is beneficial for a qualitative flow analysis to obtain relatively agreed averaged velocity and temperature. Moreover, traditionally, the RANS approach calculates only the averaged temperature distribution. It should also be emphasized that unlike the LES approach, the steady RANS approach cannot express a local flow structure in intense mixing zones. Nevertheless, apparently the used RANS approach should be used for assessing the quality of computational grids, boundary conditions in order to use the LES approach for further numerical simulation.

New Regression models for Estimation daily temperature of Karachi and its Neural Network analysis

<p>This study presents the determination of the average daily temperature distribution for Karachi city. Artificial Neural Network (ANN) has been used to predict the average daily temperature of 2018, 2019, and 2020. Two regression models (linear and non-linear) were also developed. These models are based on relative humidity and dew points. Karachi's six-year environmental datasets were used for the case study location and to establish temperature distribution models. In ANN three years, temperature data (2015-2017) was used to train and validate the NN model. The same data was used to find the regression coefficients of each model. Both models and NN are then used to estimate the average daily temperature of years 2018-2020. The statistical errors are also calculated for comparison and to evaluate the performance of both models; an excellent agreement was found between recorded and ANN estimates. Both regression models predict average daily temperature with reasonable uncertainties. However, the non-linear regression model predictions are better. The results show that the models provide a good prediction of temperature distribution.</p>

Non-Isothermal Vortex Flow in the T-Junction Pipe

The numerical simulation approach of heat carrier mixing regimes in the T-junction shows that the RANS approach is beneficial for a qualitative flow analysis to obtain relatively agreed averaged velocity and temperature. Moreover, traditionally, the RANS approach only predicts the averaged temperature distribution. This mathematical model did not consider the temperature fluctuation variations important for the thermal fatigue task. It should also be emphasized that unlike the LES approach, the steady RANS approach cannot express a local flow structure in intense mixing zones. Nevertheless, apparently the adopted RANS approach should be used for assessing the quality of computational meshes, boundary conditions with the purpose to take LES for further numerical simulation.