Estimation Of Temperature Field Research Articles

Robust Estimation of temperature field during microwave tempering under unknown dielectric properties

AbstractIn this paper, a framework is proposed for the estimation of internal temperatures within a foodstuff during microwave tempering under unknown dielectric properties. The solution is based on a partially known model issued from the closed form solutions of Maxwell's equations coupled with the conduction heat equation solved by finite differences. The algorithm converges towards acceptable dielectric properties functions whereas the temperature field is estimated simultaneously. This approach is carried out in simulation by considering the tempering of a block of raw beef located in a rectangular wave guide allowing to consider a fundamental mode with perfectly known electromagnetic conditions.

Inverse radiation analysis of simultaneous estimation of temperature field and radiative properties in a two-dimensional participating medium

An inverse radiation analysis is presented for simultaneous estimation of temperature field and radiative properties including absorption and scattering coefficients in a two-dimensional rectangular, absorbing, emitting and scattering gray medium from the knowledge of the exit radiative energy received by charge-coupled device (CCD) cameras at boundary surfaces. The backward Monte Carlo method was introduced to describe the radiative heat transfer for its efficiency. The inverse problem is formulated as an optimization problem and solved by the least-square QR decomposition (LSQR) method. The effects of measurement errors, optical thickness and search step length on the accuracy of the estimation were investigated and the results show that the temperature field and radiative properties can be reconstructed accurately for the exact and noisy data.

Heat Flux and Temperature Field Estimation Using Differential Interferometer

A new methodology based on least-squares approach has been developed to estimate the temperature field from an interferogram recorded using a Differential interferometer (DI). The interferograms are digitally evaluated using two dimensional Fourier transforms to retrieve the temperature gradient field. Temperature field is constructed by fitting a cubic spline to the first derivatives data. The methodology has been applied to both experimental and synthetic interferograms. Both convective heat flux and temperature field were predicted accurately. The role of image noise and errors in the temperature measurements on the temperature field estimation have been studied with the aid of synthetic interferograms.

Inverse radiation analysis in two-dimensional gray media using the discrete ordinates method with a multidimensional scheme

This work presents an inverse analysis for temperature field estimation in a two-dimensional gray media; it uses a multidimensional spatial scheme and high order angular quadrature in the discrete ordinates method. The participating media system contains absorbing, emitting, isotropic scattering gray medium. The radiative intensities exiting in some points of boundary surfaces, which simulate data of sensing devises, are known. In this work, the Discrete Ordinates Scheme with Infinitely Small Weight (DOS + ISW) is used to calculate data values. The conjugate gradient method is used to solve the inverse radiation problem for determining the temperature field. The inverse problem is formulated as an optimization problem that minimizes the error between the calculated and the simulated measurement of radiation intensity leaving the media that is sensed at one, two or four points at the boundary of the cavity. The numerical results are obtained by considering simulated data with and without noise. Different arrangements of the position of the sensors at the cavity boundary were analyzed. The temperature field has been estimated with accuracy by using LC11 and Tn6 angular quadratures of DOM when four or two sensors were used and the results for four and two sensors are very close. Also, the effects on the estimations of non-uniform distribution of the absorption coefficient (with random errors of 10%) were analyzed.

A comprehensive sensitivity analysis of the WRF model for air quality applications over the Iberian Peninsula

Meteorological inputs play a vital role on regional air quality modelling. An extensive sensitivity analysis of the Weather Research and Forecasting (WRF) model was performed, in the framework of the Integrated Assessment Modelling System for the Iberian Peninsula (SIMCA) project. Up to 23 alternative model configurations, including Planetary Boundary Layer schemes, Microphysics, Land-surface models, Radiation schemes, Sea Surface Temperature and Four-Dimensional Data Assimilation were tested in a 3 km spatial resolution domain. Model results for the most significant meteorological variables, were assessed through a series of common statistics. The physics options identified to produce better results (Yonsei University Planetary Boundary Layer, WRF Single-Moment 6-class microphysics, Noah Land-surface model, Eta Geophysical Fluid Dynamics Laboratory longwave radiation and MM5 shortwave radiation schemes) along with other relevant user settings (time-varying Sea Surface Temperature and combined grid-observational nudging) where included in a “best case” configuration. This setup was tested and found to produce more accurate estimation of temperature, wind and humidity fields at surface level than any other configuration for the two episodes simulated. Planetary Boundary Layer height predictions showed a reasonable agreement with estimations derived from routine atmospheric soundings. Although some seasonal and geographical differences were observed, the model showed an acceptable behaviour overall. Despite being useful to define the most appropriate setup of the WRF model for air quality modelling over the Iberian Peninsula, this study provides a general overview of WRF sensitivity and can constitute a reference for future mesoscale meteorological modelling exercises.

Through-transmission laser welding of polymers – temperature field modeling and infrared investigation

The purpose of the present study is to estimate the weldability of a polymeric material couple according to their thermal and optical properties. A first model based on Mie theory and Monte Carlo method describes the laser beam behavior in semi-transparent media and makes it possible to approximate the laser power distribution at the interface of the two materials. A second model based on finite element method permits the temperature field estimation into both parts to be welded. The results are validated by infrared thermography.

Temperature prediction for multi‐dimensional domains in standard fire

AbstractThe existing 1D analytical solution for heat conduction inside structural members plays an important role in the estimation of temperature field and prediction of member strength in fire. In this paper, the novelty lies in a set of proposed analytical formulations for the conduction heat transfer within multi‐dimensional (2D and 3D) domains subjected to a particular time‐varying boundary condition, i.e. the standard fire conditions. Solutions of multi‐dimensional conduction are based on the eigenfunction approach using the technique of separation of variables. The multi‐dimensional effect is incorporated by the product of respective solutions of 1D transient heat conduction (1D step functions) of the plate and the infinite cylinder that serve as a set of basis for derivation of analytical solutions. Fire boundary conditions are incorporated using the Duhamel's principle, where the time‐varying fire temperature curve is imposed on the step functions. In this paper, the boundary conditions of the first and the third kind are considered, respectively. The analytical solutions are compared with results obtained from finite element analysis for verification. Copyright © 2006 John Wiley & Sons, Ltd.

Application of Nonlinear Constraints in a Three-Dimensional Variational Ocean Analysis

Two kinds of nonlinear constraints, not previously studied in oceanography, have been adopted with the Preconditioned Optimizing Utility for Large-dimensional analyses (POpULar) in a three-dimensional oceanic variational analysis in the equatorial Pacific. One is the constraint for the variational Quality Control (QC) procedure and the other is used to avoid density and temperature inversions. Estimation of the large heat content anomaly in the upper ocean related to El Nino and La Nina phenomena is improved with the variational QC. For example, it prevents unusual but correct observation data on the thermocline deepening in the 1997/98 El Nino from being ignored. As a result, it improves the temperature field estimation in the eastern equatorial Pacific. The constraint for avoiding inversions prevents the low salinity layer at the surface and the barrier layer in the eastern equatorial Pacific in the El Nino period from being destroyed by the convective adjustment procedure performed after minimizing the cost function. Incorporating nonlinear constraints in variational analyses is thus a strong candidate for increasing the accuracy of analysis.

318 血流量の温度依存性を考慮した生体内温度分布の逆推定(熱工学(3))

318 血流量の温度依存性を考慮した生体内温度分布の逆推定(熱工学(3))

Corrigendum: Estimation of Global Temperature Fields from Scattered Observations by a Spherical-Wavelet-Based Spatially Adaptive Method

Fig. 2 on page 228 of the paper is incomplete. The correct version appears below. Five-level bottom-up design network: •, ℳ1 (507 stations); ∘, ℳ2 (244 stations); Δ, ℳ3 (117 stations); +, ℳ4 (49 stations); ×, ℳ5 (22 stations)

Estimation of Global Temperature Fields from Scattered Observations by a Spherical-Wavelet-Based Spatially Adaptive Method

SummaryThe paper considers the problem of estimating the entire temperature field for every location on the globe from scattered surface air temperatures observed by a network of weather-stations. Classical methods such as spherical harmonics and spherical smoothing splines are not efficient in representing data that have inherent multiscale structures. The paper presents an estimation method that can adapt to the multiscale characteristics of the data. The method is based on a spherical wavelet approach that has recently been developed for a multiscale representation and analysis of scattered data. Spatially adaptive estimators are obtained by coupling the spherical wavelets with different thresholding (selective reconstruction) techniques. These estimators are compared for their spatial adaptability and extrapolation performance by using the surface air temperature data.

AN APPLICATION OF THE GENERALIZED OPTIMAL DYNAMIC FILTRATION METHOD FOR SOLVING INVERSE HEAT TRANSFER PROBLEMS

The article deals with the mathematical modeling of transient temperature fields using data subject to uncertainties. We present the generalized optimal dynamic filtration method, developed on the unified least-squares method (ULSM) with the use of multistage-multigroup (M-M) technique. There are many advantages to be gained from that approach. We can verify the accuracy of the model, achieve more probable, from a statistical point of view, calculation results, and, what is genuinely useful, receive a detailed statistical measure of the mathematical model correctness. The application example of transient temperature field estimation in the element of a technological system is included.

Cellular neural network analysis for two-dimensional bioheat transfer equation.

The cellular neural network (CNN) method is applied to solve the Pennes bioheat transfer equation, and its feasibility is demonstrated. Numerical solutions were obtained for a cellular neural network for a two-dimensional steady-state temperature field obtained from focused and unfocused ultrasound heat sources. Transient-state temperature fields were also studied and compared with experimental results obtained elsewhere. The cellular neural networks' key features of asynchronous parallel processing, continuous-time dynamics and local interaction enable real-time temperature field estimation for clinical hyperthermia.

Using MODAS to derive subsurface sound speed estimates from satellite observations

The Modular Ocean Data Assimilation System (MODAS) provides a set of tools for analysis and manipulation of ocean data. One of its functions is the estimation of subsurface temperature and salinity fields from satellite observations of height deviation and temperature. A two-dimensional optimal interpolation of the satellite data produces fields of surface height anomaly and temperature. These data are provided to the MODAS synthetic profile routine to predict subsurface temperature and salinity fields compatible with the surface observations and local climatological statistics. Available in situ measurements may be assimilated at this stage. A sound speed field calculated from the temperature and salinity estimates provides the basis for additional acoustical applications. MODAS products, evaluated by comparison with finely sampled surveys, show significant improvement over estimates from static climatologies. [This work was funded by the Space and Naval Warfare Systems Command (SPAWAR) and the ONR through the Advanced Data Fusion Center Support and the On-Scene Tactical Ocean Forecast Capability projects (SPAWAR, Program Element 603207N) and the MODAS Improvements and the Prediction of Coastal Buoyancy Jets projects (ONR, Program Element 602435N).]

Estimation of temperature fields in local tissues during intracavitary hyperthermia

This paper presents a heat transfer model for the hyperthermia treatment of cervix cancer using a intracavitary microwave applicator and based on which the 3-D finite element simulation of the temperature fields have done. Before then the specific absorption rate (SAR) distribution for the transvaginal probe have been measured in a phantom. The variations of the parameters have been investigated, too, for optimization. At last, the results of simulation are compared to that measured in the phantom and some instructive conclusions are presented for critical application.

Temperature field estimation using electrical impedance profiling methods. I. Reconstruction algorithm and simulated results.

Algorithmic methods for estimating complete temperature fields during hyperthermia treatments based on surface and internal electrical measurements are presented. The techniques utilized draw upon impedance imaging concepts, but rather than limit the measurements to positions on the body surface, internal impedance recording sites are allowed. Theoretical simulations show that this strategy improves the reconstructed image in the target region when either internal measurement locations are added to a given number of external recording sites or some external measurement locations are replaced by internal recording positions. The algorithms developed are tested on a set of problems with increasing levels of complexity. The culmination of these investigations is a complete simulation of a hyperthermia treatment and reconstruction of a thermal image for a body cross-section of an actual cancer patient. The results of this work suggest that the surface plus internal measurement approach holds some promise as a method for estimating temperature distributions during hyperthermia treatments. However, the simulations while promising are idealizations in that they are two-dimensional with modest levels of additive noise. In a companion paper, we explore the viability of this approach in several laboratory phantom experiments which include both static and heat-induced transient electrical property profiles.

Estimate of the temperature field in a compressible medium

Estimate of the temperature field in a compressible medium

Time domain analysis of normal mode, parabolic, and ray solutions of the wave equation

Estimation of sound speed and temperature fields from tomographic data requires knowledge of the accuracy of the forward model. For this reason, time domain results using three models derived from the acoustic wave equation are compared here. The models chosen for the analysis are normal modes (NM) and the parabolic equation (PE) and ray approximations. (The NM and PE time series are obtained via Fourier synthesis). The analysis is done using a depth-dependent sound-speed profile where only refracted and surface-reflected/refracted energy is allowed to propagate. Because the NM representation is theoretically exact in this environment, it is used as the comparative base. Travel-time sequences generated using the PE and ray approximations are compared to those generated using NM. For the angular aperature analyzed (±9 to ±16.5 deg), phase errors in the PE models investigated limit reliable predictions of travel time to distances of about 1000 km. However, the ray approximation is found to be adequate for estimating arrival times at ranges out to 4000 km for frequencies of 100 Hz and above.

溶接条件の最適化に関する研究 （第１報） 最適入熱条件推定のアルゴリズム

An algorithm for optimal heat input control in arc welding has been discussed in this paper.An optimization problem of the temperature field during welding has been proposed and tackled in order to estimate an optimal sequence of heat inputs. In the expression of the problem, the analytical solution of heat flow equation is used for the estimation of temperature field, and the objective function is defined as the difference between calculated and required temperatures.The following two typical optimization problems have been investigated. The objective in the first problem is to make the temperatures at some given times and points coincide with the required temperatures, and the objective in the second problem is to make the maximum temperatures at given points coincide with the required ones.As the result of this work, it is made clear that the convex programming is a powerful means of solving the first problem and the steepest descent method is useful for the second problem.

U.S.S.R. experience in thermal design of building envelopes with improved thermal properties

This paper deals with the U.S.S.R. experience on improving thermal design of enveloping structures of precast buildings of mass-scale construction. In such buildings, multi-layer enveloping structures with improved thermal properties are becoming increasingly used. They are characterized by non-homogeneity of materials in cross-section and complex butt joints for which methods of computer estimation of temperature fields had been developed. The paper sets forth methods for estimating two- and three-dimensional tasks of heat conduction making it possible to obtain temperature fields of surfaces of envelopes, the distribution of thermal flows, and on that basis to calculate the reduced total thermal resistance of the envelope. For the purpose of codification, based on numerous estimations of temperature fields, simplified design methods of estimation of such structures have been developed. Analytical expressions of thermal characteristics of enveloping structures with the most widely used thermal bridges are given. For design purposes, a data bank has been compiled on typical thermal bridges of enveloping structures in the U.S.S.R.