Typical Temperature Distributions Research Articles

A synthetic diagnostics platform for microwave imaging diagnostics in tokamaks

Interpreting experimental diagnostics data in tokamaks, while considering non-ideal effects, is challenging due to the complexity of plasmas. To address this challenge, a general synthetic diagnostics (GSD) platform has been established that facilitates microwave imaging reflectometry and electron cyclotron emission imaging. This platform utilizes plasma profiles as input and incorporates the finite-difference time domain, ray tracing and the radiative transfer equation to calculate the propagation of plasma spontaneous radiation and the external electromagnetic field in plasmas. Benchmark tests for classical cases have been conducted to verify the accuracy of every core module in the GSD platform. Finally, 2D imaging of a typical electron temperature distribution is reproduced by this platform and the results are consistent with the given real experimental data. This platform also has the potential to be extended to 3D electromagnetic field simulations and other microwave diagnostics such as cross-polarization scattering.

Modeling and flow analysis of FDM based dual extruder

The creation of solid items in three dimensions through the utilization of computer-aided design (CAD) software is the process known as additive manufacturing. The FDM (Fused Deposition Modeling) process is one type of additive manufacturing (AM) process, and the extruder is the most important part of that process. In particular, the design of a multi-material extruder is an example of a typical problem. The purpose of this study is to make an attempt to design a multi-material extruder that can mix materials and colors at the printhead of an FDM process printer. Additionally, a CFD study is carried out with the modeled component in order to comprehend the thermal properties. During material flow in the mixing chamber, a typical temperature distribution and flow analysis can be found. Various fluid flow rates (0.2, 0.5, and 1 mm/sec) were utilized in order to conquer these challenges. According to the findings, the optimal parameters for mixing of PLA and ABS materials are good at a flow rate of 0.5 mm/sec and a simulation time of 50 s.

Thermal vibration analysis of functionally graded circular plates based on Levinson’s third-order shear deformation theory

In this article, the free vibration behavior of functionally graded circular Levinson plates is investigated. Hamilton’s principle is adopted to derive the governing equation of the system, which effectively takes into account the effects of both thermal stress and physically neutral surfaces. With the devised formulation, three typical temperature distributions and temperature-dependent (TD) features are studied. The natural frequencies of the corresponding functionally graded plates can be computed through the use of the differential quadrature method. Hence the impacts due to temperature fields, volume fraction index, TD characteristics, and thickness-to-radius ratio on the natural frequency of functionally graded circular plates can be quantitatively analyzed.

Critical position of fatigue damage within asphalt pavement considering temperature and strain distribution

ABSTRACT The fatigue properties of the asphalt pavement layer are influenced significantly by different strain levels and temperatures. This research investigated the critical fatigue position within the asphalt pavement layer considering the couple effects of strain levels and temperatures. Firstly, field tests were conducted to measure the typical temperature distribution of the asphalt pavement layer. Secondly, laboratory four-point beam fatigue test and dynamic modulus test were applied to evaluate the fatigue life and the dynamic modulus of the asphalt mixture, respectively. Based on the results of field and laboratory tests, the distributions of strain and fatigue damage within the asphalt layer at different temperature conditions were calculated. It was found that the fatigue life of asphalt mixture decreased with the rising strain level but increased with the rising temperature. The critical fatigue position in the flexible pavement changed from 5 to 20 cm when the pavement temperature condition varied from high to medium/low. In terms of the semi-rigid pavement, this position varied between 6 and 12 cm at different temperature conditions. In addition, the fatigue damage within the semi-rigid pavement at high temperature was found to be as noticeable as that at medium/low temperatures. Thus, the fatigue properties of the asphalt layer at higher temperatures need to be carefully evaluated as well.

Thermal cracking prediction of frameless glazing exposed to radiant fluxes increasing with height

SummaryThe prediction of losing integrity of glazing elements exposed to compartment fires is important in building fire safety. Existing criterion is only appropriate for framed glazing but not frameless glazing due to omission of the flexing stress in the former. A robust and directly applicable expression to determine the location and time of thermal cracking of frameless glazing is lacking in the literature. In this work, thermal stress calculations including the effect of flexing stress were performed based on typical temperature distributions of glazing exposed to compartment fires, and then simple expressions of the maximum stress were derived. Besides, experiments of frameless glazing exposed to heat radiation were carried out to verify the applicability and accuracy of the obtained expressions, as well as to investigate the cracking behavior of frameless glazing. Results show that the proposed expression of maximum stress agrees well with the experimental cracking behavior. Cracks start from the bottom edge and the upper edge of the glazing when exposed to typical distribution of radiant fluxes from compartment fires. In addition, flexing stress has significant contribution to the total stress field.

Net Emission Coefficient and Radiation Transfer Characteristics of Thermal Plasma Generated in Nitrogen-PTFE Vapor Mixture

The radiation characteristics of thermal plasma columns filled with N2-polytetrafluoroethylene vapor mixture has been studied for the first time. The net emission coefficient is first calculated for typical mixture concentrations. The discrete ordinate method (DOM), which has proven to be an approximate method of reasonable accuracy for radiation transfer in thermal plasmas, is then used to characterize the emission and absorption behavior of cylindrical plasma columns with typical temperature distributions. Results show that the radiative power loss per unit volume at the column center is not always proportional to the local gas pressure. The DOM12-9 configuration, i.e., considering 24 directions in the $r$ -plane of the calculation point and 18 directions crossing the $r$ -plane, produces remarkably accurate results. It is likely to recover the accurate emission and absorption profile by scaling the output from the DOM5-3 configuration with a scaling factor between 0.7 and 0.8. Furthermore, the DOM5-3 configuration accurately locates the absorption layer at the edge of the plasma column. Maximum absorption takes place at a radial location whose distance to the inner radius of the absorption layer is 30% of the layer thickness despite of the very different radial temperature profiles. Under the conditions studied 35%–60% of the radiation from the central part of the column is absorbed in the surrounding cooler gas.

A thermoelastic deformation model of tissue contraction during thermal ablation

Purpose: Thermal ablation is an energy-based ablation technique widely used during minimally invasive cancer treatment. Simulations are used to predict the dead tissue post therapy. However, one difficulty with the simulations is accurately predicting the ablation zone in post-procedural images due to the contraction of tissue as a result of exposure to elevated temperatures.Materials and methods: A mathematical model of the thermoelastic deformation for an elastic isotropic material was coupled with a three state thermal denaturation model to determine the contraction of tissue during thermal ablation. A finite difference method was considered to quantify the tissue contraction for a typical temperature distribution during thermal ablation.Results: The simulations show that tissue displacement during thermal ablation was not bound to the tissue heated regions only. Both tissue expansion and contraction were observed at the different stages of the heating process. Tissue contraction of up to 42% was obtained with an applicator temperature of 90 °C. A recovery of around 2% was observed with heating removed as a result of unfolded state proteins returning back to its native state. Poisson’s ratio and the applicator temperature have both been shown to affect the tissue displacement significantly. The maximum tissue contraction was found to increase with both increasing Poisson’s ratio and temperature.Conclusions: The model presented here will allow predictions of thermal ablation to be corrected for tissue contraction, which is an important effect, during comparison with post-procedural images, thus improving the accuracy of mathematical simulations for treatment planning.

Hot stamping of patchwork blanks: modelling and experimental investigation

Hot stamping of patchwork blanks is flexible to adjust the mechanical properties of the component by applying patched blanks with different thicknesses and at different locations. Efficient process analysis needs a sophisticate finite element (FE) model for numerical simulation. A novel thermal–mechanical coupled FE model for hot stamping of patchwork blank was developed considering the thermal dependent failure of welding spots. The failure of the welding spots was evaluated by shear strength, which was characterized by tensile shear tests under different temperatures. Furthermore, the welding current and the arrangement of welding spots were determined to produce the patchwork blank. The locations and causes of forming defects, e.g. wrinkling and crack in hot stamping of a B-pillar with patchwork blanks, were analyzed. With numerical simulations and experimental investigations, the optimum process parameters were obtained. For predicting the thickness of typical sections and temperature distributions on the B-pillar for patchwork blank, the errors between numerical and experimental results were less than 10% in thickness distribution, and the maximum error was only 14.5% in temperature distribution. Experimental and simulation results show that the developed FE model is reliable and can be used to predict the results and improve the hot stamping process of patchwork blank.

Mathematical model of heat and mass transfer in a geothermal reservoir upon extraction of steam and water mixture

A mathematical model of heat and mass transfer in a geothermal reservoir saturated with steam and water mixture upon the extraction of heat carrier through a single well is considered. The exact solution of the time-independent and quasi-time-independent nonlinear problems is obtained. Typical water saturation, temperature, and pressure distributions around a well are shown. Conditions for the regimes of heat and mass transfer, the violation of which leads to the formation of a region saturated with either pure fluid of pure steam, are found. Parametric studies are performed.

Electrochemical-Thermal Characterization and Modeling of Large Format Prismatic Lithium Ion Batteries

Large-format prismatic lithium-ion cells can generate substantial heat during operation, making thermal management significant. Some cells have high surface-to-volume ratios, and the positioning of tabs can make surface temperature highly non-uniform [1], posing further thermal management challenges. Non-uniformity of temperature is a major problem because a battery operated at a safe average temperature can still have ‘hot spots’ that are prone to thermal runaway [2]. Depending on the battery’s ability to dissipate heat to its surroundings, thermal runaway may nucleate in very small volumes. The thermal responses of prismatic lithium-ion batteries arise from a number of distinct phenomena that occur as the cell is subjected to an electrical load. Current flow generates joule heat, which is always dissipated, regardless of the sign of the current; this may arise either from ohmic resistance or from the resistances associated with charge-transfer reactions. There is also reversible heat, which may be dissipated or consumed according to the current’s sign; such heat owes to the entropy associated with the electrochemical reaction that occurs as the state of charge (SOC) is changed [3]. We have developed a 3D finite-element model that accounts for these various modes of heating within the battery cell, which runs with sufficient computational efficiency to allow parameterization by fitting model output to dynamic experimental voltage and temperature-distribution data. Our approach provides an ‘outside-in’ method that allows external measurements to be correlated with internal material properties. A simple physics-based model based on the Newman-Tobias porous-electrode theory [4] is augmented with energy equations to predict electrical and thermal behavior. The model can then also be used to extract material properties. We aim to characterize the macroscopic effects of charge/discharge induced thermal response across a cell’s available charge states to provide insight into battery state of health (SOH). Square wave signals with amplitudes of C-rates ranging from 1C to 4C and periods ranging from 20s to 100s were applied to A123 20Ah LiFePO4 prismatic cells beginning at fixed SOC. This input signal was chosen so that the average SOC remains constant, eliminating concerns regarding how material properties change depending on charge state. Temperature distributions were measured using infrared thermography; this data was gathered dynamically and synchronized with the cell-voltage data gathered during the square-wave excitation tests. Figure 1 shows typical temperature distributions across three C-rates (1C, 2C, 4C) at a fixed period of 100s at an average SOC of 50%. As C-rate increases, not only does the overall temperature of the cell increase, but the difference in temperature across its surface also varies. Material properties of batteries – including the propensity for thermal runaway – depend strongly on SOC [5]. By fitting the thermographic data gathered around different mean SOCs, it is possible to extract these SOC-dependent parameter values. Some discussion will also touch on how the model can be used to track material properties as they vary with respect to cycling history, providing possible insight into SOH estimation. 1. Robinson, J.B., et al., Detection of Internal Defects in Lithium-Ion Batteries Using Lock-in Thermography. ECS Electrochemistry Letters, 2015. 4(9): p. A106-A109. 2. Bandhauer, T.M., S. Garimella, and T.F. Fuller, A Critical Review of Thermal Issues in Lithium-Ion Batteries. Journal of The Electrochemical Society, 2011. 158(3): p. R1-R25. 3. Thomas, K.E. and J. Newman, Heats of mixing and of entropy in porous insertion electrodes. Journal of Power Sources, 2003. 119–121: p. 844-849. 4. Newman, J.S. and C.W. Tobias, Theoretical Analysis of Current Distribution in Porous Electrodes. Journal of The Electrochemical Society, 1962. 109(12): p. 1183-1191. 5. Maleki, H., et al., Thermal Stability Studies of Li‐Ion Cells and Components. Journal of The Electrochemical Society, 1999. 146(9): p. 3224-3229. Figure 1

Constraining the physical structure of the inner few 100 AU scales of deeply embedded low-mass protostars

(Abridged) The physical structure of deeply-embedded low-mass protostars (Class 0) on scales of less than 300 AU is still poorly constrained. Determining this is crucial for understanding the physical and chemical evolution from cores to disks. In this study two models of the emission, a Gaussian disk intensity distribution and a parametrized power-law disk model, are fitted to sub-arcsecond resolution interferometric continuum observations of five Class 0 sources, including one source with a confirmed Keplerian disk. For reference, a spherically symmetric single power-law envelope is fitted to the larger scale ($\sim$1000 AU) emission and investigated further for one of the sources on smaller scales. A thin disk model can approximate the emission and physical structure in the inner few 100 AU scales of the studied deeply-embedded low-mass protostars and paves the way for analysis of a larger sample with ALMA. While the disk radii agree with previous estimates the masses are different for some of the sources studied. Assuming a typical temperature distribution, the fractional amount of mass in the disk above 100 K varies in between 7% to 30%. Kinematic data are needed to determine the presence of any Keplerian disk. Using previous observations of p-H$_2^{18}$O, we estimate the relative gas phase water abundances roughly an order of magnitude higher than previously inferred when both warm and cold H$_2$ was used as reference. A spherically symmetric single power-law envelope model fails to simultaneously reproduce both the small and large scale emission.

Numerical Investigation of a Packed Bed Thermal Energy Storage System with Different Heat Transfer Fluids

This paper presents the results of a numerical investigation on the transient behaviour of a packed bed thermal storage unit using different fluids: oil, molten salt and air. The storage material consists of loosely spherical particles of alumina packed in a reservoir wherein the heat transport fluid flows from the top to the bottom in the charging phase, and in the opposite way in the discharging phase. The process of charge/discharge of the storage system gives rise to a typical temperature distribution along the flow direction defined “thermocline”. The main objective of this work is to analyze the temperature distribution along the storage system and the formation of the thermocline for repetitive consecutive cycles, evaluating the progressive reduction of the stored energy in the solid material for every new cycle. The numerical investigation is based on a two-phase one-dimensional modified Schumann model, where thermodynamic properties of the fluid are temperature dependent.

Removal of phosphorus in molten silicon by electron beam candle melting

In the current study, a new method for the removal of phosphorus in molten silicon, electron beam candle melting (EBCM), is proposed and discussed. The proposed method combines the characteristics of electron beam melting (EBM) and the high saturated vapor pressure of P in molten Si. Simulation results show the existence of three typical temperature distributions and morphologies of the molten pool that correspond to the different radii of the electron beam circular pattern at constant power. The critical molten pool with the maximum surface area and the minimum depth was determined. EBCM resulting in the critical molten pool was proven to be more effective in the removal of P in molten Si compared with EBM. In addition, the energy utilization ratio was enhanced.

Corrigendum to “On the feasibility of friction spot joining in magnesium/fiber-reinforced polymer composite hybrid structures” [Mater. Sci. Eng. A 528 (2011) 3841–3848

The authors regret that a number of errors were included in the second paragraph of Section 4.1 of their paper. For the readers onvenience, Section 4.1 of the paper has been reproduced below. The authors would like to apologise for any inconvenience caused. 4.1. Temperature field formation Fig. 5A presents selected results showing a typical temperature distribution in the clamping ring of a friction-spot joined PPSCF/AZ31 ingle-lap connection (1500 rpm, 0.25 mm, 8 s and 3 bar). Temperatures within the regions closer to the magnesium plate exhibited the ighest values varying between approximately 400 ◦C and 440 ◦C. Fig. 5B shows thermometric results for the same joint. Thermocouple T1, which is the nearest measurement point to the metal plastiizing volume (15.5 mm from the spot center and 1.5 mm deep in the metal partner), gives the highest temperature values, of about 275 ◦C, ollowed by thermocouples T2 and T4 (21.5 mm from the spot center and 1 mm into the metal partner and 8.5 mm from the spot center nd between partners, respectively), which registered temperatures around 170 ◦C and 225 ◦C, respectively. Thermocouples T3 and T5 resented the lowest maximum temperatures (120 ◦C and 90 ◦C, respectively). This is probably due to their distance from the heat source 32.5 mm from the spot center and 1 mm deep in the metal partner in the case of T3, whereas T5 was placed at the bottom of the PPS-CF laque, in the middle of the spot center). The peak temperatures measured represent 50–80% of the melting point of AZ31B, which is in accordance with temperatures measured uring friction stir welding with similar process conditions [18,34]. This is within the range of dynamic metallurgical transformations for Z31B [35]. In this way, microstructural changes are expected to occur during joining. The results of the temperature development for the PS-CF composite–AZ31 joints indicated that the process temperature is directly proportional to the energy input. Comparable to friction pot welding of metals, energy input is dictated by the welding parameters, such as rotational speed, joining time and tool plunge rate. A arametric study of the relationship between energy input, temperature and process by statistical analysis is forthcoming.

Transient natural convective heat transfer of a low-Prandtl-number fluid inside a horizontal circular cylinder with an inner coaxial triangular cylinder

A numerical study of transient natural convection of liquid gallium (Pr = 0.023) from a horizontal triangular cylinder to its coaxial cylindrical enclosure is performed. The aspect ratio is fixed at 2 and two positions of the inner triangular cylinder are considered. The development of the convective flow and heat transfer is shown via the time histories of the average Nusselt number over the outer circular wall for various Grashof numbers. Temporal phases of the flow development are identified as: initializing, developing, transitioning, and steady/quasi-steady state or oscillating. Typical flow patterns and temperature distributions at these phases are presented by means of streamlines and isotherms, respectively. Pitchfork bifurcation is present for both positions of the inner triangular cylinder when Gr ⩾ 5 × 10 4. The time-averaged Nusselt number over the outer circular cylinder, the flow development time, and the onset time of pitchfork bifurcation are predicted and scaled with the Grashof number. It is found that the time-averaged Nusselt number is apparently increased by horizontally placing the top side of the inner triangular cylinder for Gr ⩾ 1 × 10 5.

Internal gravity waves in the thermosphere during low and high solar activity: Simulation study

Propagation of internal gravity waves (GWs) from the lower atmosphere into the upper thermosphere, and their dynamical and thermal effects have been studied under low and high solar activity approximated by the F10.7 parameter. It has been done by using a nonlinear spectral parameterization in systematic offline calculations with typical wind and temperature distributions from the HWM and MSISE‐90 models, and with interactive simulations using the University College London Coupled Middle Atmosphere‐Thermosphere‐2 (CMAT2) general circulation model (GCM) under solstice conditions. The estimates have been performed for relatively slow harmonics with horizontal phase velocities less than 100 m s−1, which are not affected by reflection and/or ducting. GW drag and wave‐induced heating/cooling are shown to be smaller below ∼170 km at high solar activity, and larger above. The maxima of GW momentum deposition occur much higher in the upper thermosphere, but their peaks are half as strong, 120 vs 240 m s−1 day−1 in the winter hemisphere when the insolation is large. Instead of strong net cooling in the upper thermosphere, GWs produce a weak heating at high solar activity created by fast harmonics less affected by dissipation. Molecular viscosity increases with solar activity at fixed pressure levels, but seen in Cartesian altitude grids it can either increase or decrease in the lower thermosphere, depending on the height. Therefore, in pressure coordinates, in which most GCMs operate, the influence of larger temperatures can be viewed as a competition between the enhanced dissipation and vertical expansion of the atmosphere.

Synoptic-scale anomalies of Lake Ladoga surface temperature fields

Results of studying characteristic features of variability of the water surface temperature fields of Lake Ladoga during the open water period are presented. Anomalies and extreme deviations of real spatial distributions from those typical of the scales of synoptic variability are estimated. Typical surface temperature distribution of Lake Ladoga during an open water period occupies not more than 20% of the lake area. The near-shore shallow water area is characterized as an area of most anomalous water temperature distribution. The abnormality extent changes from month to month. July is the most anomalous month of the open water period.

Thermo-hydraulic analysis of the gradual cool-down to 80 K of the ITER toroidal field coil

A time-dependent thermo-hydraulic simulation for an ITER toroidal field (TF) coil gradual cool-down to 80 K has been performed using a new FORTRAN code. The code is based on a 1D helium flow and 1D multi-region solid heat conduction model. The whole TF coil is simulated taking into account thermal conduction between winding pack and case, which are cooled down separately. To limit coil mechanical stresses and coolant pressure drop in the cooling channels, an improved cool-down mode has been developed based on the analysis. Typical and gradual cool-down temperature distributions of TF coil and case are presented. The results indicate that gradual cool-down to 80 K can be achieved in 3 weeks.

중위도 기상조건에서 함정의 연돌 방사율을 고려한 적외선 복사량 예측 및 감소방안 연구

This study is focused on developing a software that predicts the temperature distribution and infrared Emission from 30 objects considering the solar radiation through the atmosphere. The solar radiation through the atmosphere is modeled by using the well-known LOWTRAN7 code. Surface temperature information is essential for generating the infrared scene of the object. Predictions of the transient surface temperature and the infrared emission from a naval ship by using the software developed here show fairly good results by representing the typical temperature and emitted radiance distributions expected for the naval ship considered in mid latitude. Emissivity of each material is appeared to be an important parameter for recognizing the target in Infrared band region. The numerical results also show that the low emissivity surface on the heat source can be helpful in reducing the IR image contrast as compared to the background sea.

東京湾における季節特性を考慮した湾内流動の再現計算

This study describes typical mass transports in spring, summer, autumn and winter in Tokyo Bay by using a non-hydrostatic model, MEL3D. Some typical salinity and water temperature distributions in each season obtained from field observation were used in the numerical computation. Furthermore, spatial distributions of wind over Tokyo Bay evaluated using nine meteorological observation stations were applied in the computation as boundary conditions. To investigate mass transport, neutral particle tracking simulations were carried out by putting particles along near the coastal line by about 4km. As the results, especially in summer, it was demonstrated that the characteristic of the neutral particle transport in Tokyo Bay is strongly affected by the vertical current of circulation around the western coast in the head of Tokyo Bay.