Measurements Of Thermal Radiation Research Articles

Validating heat balance models for tungsten dust in cold dense plasmas

The first comparison of dust radius and surface temperature estimates, obtained from spectroscopic measurements of thermal radiation, with simulations of dust heating and vaporization by the MIGRAINe dust dynamics code is reported. The measurements were performed during controlled tungsten dust injection experiments in the cold and dense plasmas of Pilot-PSI, reproducing ITER divertor conditions. The comparison has allowed us to single out the dominating role of the work function contribution to the dust heating budget. However, in the plasmas of interest, dust was found to enter the strong vaporization regime, in which its temperature is practically insensitive to plasma properties and the various uncertainties in modeling. This makes the dust temperature a poor figure of merit for model validation purposes. On the other hand, simple numerical scalings obtained from orbital-motion-limited estimates were found to be remarkably robust and sufficient to understand the main physics at play in such cold and dense plasmas.

Thermal radiation in dust flame propagation

The role of thermal radiation in premixed flame propagation has been a matter for debate for decades. And it is not only a challenging scientific point, it has significant practical implications. For instance, a route to explain the Buncefield explosion (HSL, 2009) was the implication of tiny particles raised by the blast and promoting flame acceleration through enhanced heat exchanges by thermal radiation in the flame front. In dust explosion protection, the flame is implicitly supposed to propagate like a in a gaseous mixtures but if thermal radiation is dominant for some dusts, many aspects concerning the way to mitigate the explosions for those particular dusts would need to be revised (Proust and al., 2013). In this paper, new experimental measurements of thermal radiation in dust flames (methane air, methane air seeded with inert particles, aluminum dust air flames) are presented together with a physical interpretation.

ATMS‐ and AMSU‐A‐derived hurricane warm core structures using a modified retrieval algorithm

AbstractThe Advanced Technology Microwave Sounder (ATMS) is a cross‐track microwave radiometer. Its temperature sounding channels 5–15 can provide measurements of thermal radiation emitted from different layers of the atmosphere. In this study, a traditional Advanced Microwave Sounding Unit‐A (AMSU‐A) temperature retrieval algorithm is modified to remove the scan biases in the temperature retrieval and to include only those ATMS sounding channels that are correlated with the atmospheric temperatures on the pressure level of the retrieval. The warm core structures derived for Hurricane Sandy when it moved from tropics to middle latitudes are examined. It is shown that scan biases that are present in the traditional retrieval are adequately removed using the modified algorithm. In addition, temperature retrievals in the upper troposphere (~250 hPa) obtained by using the modified algorithm have more homogeneous warm core structures and those from the traditional retrieval are affected by small‐scale features from the low troposphere such as precipitation. Based on ATMS observations, Hurricane Sandy's warm core was confined to the upper troposphere during its intensifying stage and when it was located in the tropics but extended to the entire troposphere when it moved into subtropics and middle latitudes and stopped its further intensification. The modified algorithm was also applied to AMSU‐A observation data to retrieve the warm core structures of Hurricane Michael. The retrieved warm core features are more realistic when compared with those from the operational Microwave Integrated Retrieval System (MIRS).

Thermal Radiation Measurement With Thermoresistive Sigma–Delta Modulator

This paper presents a radiometer project based on a sigma–delta modulator. A model of the static and dynamic instrument behavior is made, relating the parameters of a sensor/heater to noise and measurement error. It is shown that the output binary code has a linear relationship with the power being measured independent of the sensor’s nonlinearity. Experimental results obtained from a prototype ratify the results predicted by modeling, showing that this approach can be useful as a basis for generating a digital output related to the unknown power.

Max Planck and the birth of the quantum hypothesis

Based on the functional dependence of entropy on energy, and on Wien's distribution for black-body radiation, Max Planck obtained a formula for this radiation by an interpolation relation that fitted the experimental measurements of thermal radiation at the Physikalisch Technishe Reichanstalt (PTR) in Berlin in the late 19th century. Surprisingly, his purely phenomenological result turned out to be not just an approximation, as would have been expected, but an exact relation. To obtain a physical interpretation for his formula, Planck then turned to Boltzmann's 1877 paper on the statistical interpretation of entropy, which led him to introduce the fundamental concept of energy discreteness into physics. A novel aspect of our account that has been missed in previous historical studies of Planck's discovery is to show that Planck could have found his phenomenological formula partially derived in Boltzmann's paper in terms of a variational parameter. But the dependence of this parameter on temperature is not contained in this paper, and it was first derived by Planck.

The comparison of IR and MW ground-based measurements of total precipitable water

Water vapor is one of the basic climate gases playing a key role in various processes at different altitudes of the Earth’s atmosphere. An intercomparison and validation of different total precipitable water (TPW) measurement methods are important for determining the true accuracy of these methods, the shared use of data from multiple sources, the creation of data archives of different measurements, etc. In this paper, the TPW values obtained from measurements of solar IR spectral radiation (~8–9 μm absorption band) and thermal MW radiation of the atmosphere (1.35 cm absorption line) for 138 days of observation are compared. Measurements have been carried out from March 2013 to June 2014 at Peterhof station of the St. Petersburg State University in (59.88° N, 29.82° E). It is shown that MW measurements usually give higher TPW values than IR measurements. The bias between the two methods varies from 1 to 8% for small and large TPW values, respectively. With increasing TPW values, the bias reduces and for TPW > 1 cm it is ~1%. Standard deviation (SD) between the two methods reaches 7% for TPW 1 cm. These data show the high quality of both remote sensing methods. Moreover, the IR measurements have a higher accuracy than MW measurements for small TPW values.

Quantum interferometric measurements of temperature

We provide a detailed description of the quantum interferometric thermometer, which is a device that estimates the temperature of a sample from the measurements of the optical phase. For the first time, we rigorously analyze the operation of such a device by studying the interaction of the optical probe system prepared in a single-mode Gaussian state with a heated sample modeled as a dissipative thermal reservoir. We find that this approach to thermometry is capable of measuring the temperature of a sample in the nanokelvin regime. Furthermore, we compare the fundamental precision of quantum interferometric thermometers with the theoretical precision offered by the classical idealized pyrometers, which infer the temperature from a measurement of the total thermal radiation emitted by the sample. We find that the interferometric thermometer provides a superior performance in temperature sensing even when compared with this idealized pyrometer. We predict that interferometric thermometers will prove useful for ultraprecise temperature sensing and stabilization of quantum optical experiments based on the nonlinear crystals and atomic vapors.

Theoretical, experimental and numerical study of infrared radiation heat transfer in a drying furnace

This paper aims at the study of thermal radiation heat transfer in a drying furnace considering: heating surfaces, reflector shield and load material for three power levels: 27 kW, 41 kW and 55 kW. An algorithm was developed to calculate the energy rate transferred to the load by radiation, the heat losses, and the radiation efficiency. The algorithm was validated with an experimental setup. The thermal radiation measurement methodology called “simplified view factor method for radiative heat flux measurement” was modified to measure thermal radiation in rectangular areas by the introduction of a correction factor. This factor had a good agreement with the numerical simulations. Also, it was possible to carry out the thermal characterization of an infrared radiation drying furnace at low temperature. It was determined that these kind of furnaces have a radiation efficiency of not more than 32%. Furthermore, it was found theoretically and experimentally that the radiation efficiency is almost constant for all power levels.

Single-crystal Brillouin spectroscopy with CO2 laser heating and variable q.

We describe a Brillouin spectroscopy system integrated with CO2 laser-heating and Raman spectroscopic capabilities. Temperature is determined by measurements of the grey-body thermal radiation emitted by the hot sample, with the system response calibrated relative to a standard tungsten ribbon lamp. High-pressure laser-heating Brillouin scattering measurements of acoustic velocities on liquid water and ice compressed in a diamond-anvil cell were performed at temperatures up to 2500 ± 150 K at high pressure. Single-crystal laser-heating Brillouin measurements were made on the (111) plane of San Carlos olivine at ∼13 GPa, 1300 ± 200 K. The pressure as measured by ruby fluorescence is shown to be within ±0.5 GPa of the pressure on the olivine sample during laser heating when KCl and KBr are used as pressure-transmitting media. In addition, the system is designed for continuously variable scattering angles from forward scattering (near 0° scattering angle) up to near back scattering (∼141°). This novel setup allows us to probe a wide range of wave vectors q for investigation of phonon dispersion on, for example, crystals with large unit cells (on the scale of hundreds of nm).

Near-field thermal radiation between doped silicon plates at nanoscale gaps

Radiative heat transfer can be significantly enhanced via photon tunneling through a nanometer-scale gap to the point that it exceeds the blackbody limit. Here we report quantitative measurements of the near-field thermal radiation between doped-Si plates ($\text{width}\phantom{\rule{0.28em}{0ex}}=\phantom{\rule{0.28em}{0ex}}480\phantom{\rule{0.28em}{0ex}}\ensuremath{\mu}\text{m}$ and $\text{length}\phantom{\rule{0.28em}{0ex}}=\phantom{\rule{0.28em}{0ex}}1.34\phantom{\rule{0.28em}{0ex}}\mathrm{cm}$). A novel MEMS-based platform enables us to maintain doped-Si plates at nanoscale gap distances that cannot be achieved by other methods. The measured radiative heat transfer coefficient was found to be 2.91 times greater than the blackbody limit at a 400-nm vacuum gap.

Evaluation of healing of pressure ulcers through thermography: a preliminary study

Introduction: Thermography is a surface thermal radiation measurement technique whose application has been expanding in the healthcare field. The unhealed wound is a serious public health problem because it intervenes in the quality of life of patients and may cause emotional and psychological losses. The wound temperature can provide quantitative data that allow for the healing process to be monitored. The aim of this study was to verify whether thermography can be used as a method to evaluate the healing of pressure ulcers. Methods: Eight participants with sacral pressure ulcers were recruited and randomly divided into two groups: A (control) and B (experimental). Both groups received standard treatment for a period of four weeks, which consisted of a daily cleaning of the pressure ulcers with physiological saline (sodium chloride 0.9%) followed by an alginate hydrogel dressing. The group B received light-emitting diode (LED) phototherapy in addition to standard treatment, three times a week, yielding a total of 12 sessions. Photographs and thermograms of each pressure ulcer were obtained in all sessions in both groups. Results: Pressure ulcers treated with LED phototherapy were healed. The pressure ulcer area of group B decreased over the 12 treatment sessions, whereas the pressure ulcer area of group A increased. The ulcer temperature of group B was higher than that of group A during the treatment (temperature difference up to 7.6%). Discussion: The present study suggests a relationship between the temperature and area of pressure ulcers and proposes thermography as an adjunctive method for the evaluation of healing processes.

Thermomechanical characterization of Portevin–Le Châtelier bands in AlMg3 (AA5754) and modeling based on a modified Estrin–McCormick approach

The purpose of the current work is the experimental investigation and modeling of Portevin–Le Châtelier (PLC) band development in AlMg3 aluminum alloys, in particular in AA5754. The experimental investigation employs both mechanical and thermal (infrared) radiation measurement methods. The former involve force, displacement, and strain measurements using strain gauges. The latter employ a high-speed infrared camera to capture PLC band trajectories and evolution. In addition, the critical strain for band nucleation, as well as band characteristics such as velocity, type, and strain state, have been determined. To model the experimental results, a modification of the Estrin–McCormick model (e.g., Estrin and McCormick, 1991) due to Böhlke et al. (2009) is employed. In this modification, the saturation value of the Cottrell–Bilby–Louat (CBL) contribution to the effective flow stress due to dynamic strain aging is not constant, but rather is assumed to be linearly dependent on the accumulated effective inelastic strain. This model is incorporated into a finite-element model for the experimental specimens constructed with the help of convergence and mesh-sensitivity studies. Using selected mechanical test data, model parameters for AA5754 are then identified. With the identified model, a number of comparisons between experimental results and model predictions are carried out for validation purposes. Attention is focused here in particular on aspects of PLC band nucleation and propagation. Nucleation behavior is studied in particular with respect to stress gradients. It was found that the stress gradient is not the main trigger for PLC band nucleation, and is less relevant with increasing strain. The comparison of experimental and simulation results for spatio-temporal strain patterns and stress distribution shows that strong stress drops are correlated with the start of longitudinal propagation of a fully evolved PLC band. Small oscillations between large stress drops during propagation of type B bands indicate the consecutive nucleation, propagation and disappearing of these bands. The transition region from normal to inverse behavior (decreasing strain rate) denotes the transition from type A to type B. A transition with increasing strain is observed both experimentally and in the simulation. For lower strain rates and higher strains, type C bands are observed as well. Generally speaking, the band velocity decreases with decreasing strain rate and increasing strain. On the other hand, the band strain is found to increase with increasing strain, and only slightly with increasing strain rate. Simulation and experimental results, generally, show very good agreement.

Acoustic thermometry of the patient brain with traumatic brain injury

Non-invasive deep brain acoustic thermometry is carried out for two patients at Burdenko Neurosurgery Institute. This method is based on the measurements of the own thermal acoustic radiation of the investigated object. These two patients have got the brain injury. Some of their skull bones are absent. Infrared thermometry was also used to measure the surface temperature of the forehead skin. On the basis of the experimental data the temperatures deep within the brain were reconstructed. The values for the two patients are equal to 37.3 0.7 and 37.0 0.3 degrees C.

Development and testing of a simple heat gauge for the measurement of high-intensity thermal radiation

A simple and inexpensive radiation heat gauge was developed and tested for high-intensity thermal radiation measurements. The gauge used a thermal image camera to record the temperature variation of a metallic bar painted in black and heated at one end by thermal radiation. The average flux of the irradiation was determined from the rate of temperature change at a selected point on the bar. The aperture of the gauge can be easily varied by changing the diameter of the washer in front of the metallic bar. Numerical solutions were obtained for the transient heat conduction process in the metallic bar, and casted into dimensionless forms which can be conveniently used for bars of different sizes and materials, and/or subjected to different radiation fluxes. The gauge was employed to measure the radiation beams produced by a commercial IR (Infrared) heater and the results were in good agreement with the heater manufacturer's data.

In-Flight Particle Measurement of Alkali-Free Glass Raw Materials in 12-Phase AC Arc Plasma

In-flight particle measurements of the surface temperature and velocity are important for understanding of melting behavior of glass particles during in-flight melting by multi-phase AC arc plasma. However, the use of optical pyrometry for particle surface temperature has inevitable uncertainties due to non-thermal emissions signals from the plasma plume. This work presents spectroscopic measurements of the non-thermal signals which were found to be caused mainly by the plasma emissions scattered by the particles and the radiation emitted by vapor. After that, the accuracy of thermal radiation measurement was estimated and surface temperature of in-flight glass particle was corrected.

Detection of Defects in Kenaf/Epoxy using Infrared Thermal Imaging Technique

Lignocellulosic fibrous polymeric composite materials have become an attractive replacement for heavier metals due to their superior fatigue and corrosion properties. In this study, Infrared (IR) thermal imaging technique has been used to detect the defect in unidirectional Kenaf bast fibre reinforced composite materials. IR thermal imaging technique or IR thermography is a surface thermal radiation measurement technique that is used to detect spatial variations in the measured surface temperature pattern. Thermography reveals flaws by searching anomalous hot-spots after thermal excitation. Thermography can be either categorized as active or passive. An active Infrared thermography has been proven to be a viable non-destructive testing for composite structures. In active thermography the surface of a sample is heated using an external heat source and then the surface temperature is monitored. The thermography analyses were verified by optical microscope and scanning electron microscope (SEM) investigations. The defect detection accuracy of this technique is 95%.

IMPACTS OF PARAMETERS ADJUSTMENT OF RELATIVISTIC MEAN FIELD MODEL ON NEUTRON STAR PROPERTIES

Analysis of the parameters adjustment effects in isovector as well as in isoscalar sectors of effective field based relativistic mean field (E-RMF) model in the symmetric nuclear matter and neutron-rich matter properties has been performed. The impacts of the adjustment on slowly rotating neutron star are systematically investigated. It is found that the mass–radius relation obtained from adjusted parameter set G2** is compatible not only with neutron stars masses from 4U 0614+09 and 4U 1636-536, but also with the ones from thermal radiation measurement in RX J1856 and with the radius range of canonical neutron star of X7 in 47 Tuc, respectively. It is also found that the moment inertia of PSR J073-3039A and the strain amplitude of gravitational wave at the Earth's vicinity of PSR J0437-4715 as predicted by the E-RMF parameter sets used are in reasonable agreement with the extracted constraints of these observations from isospin diffusion data.

Origin of Molecular Outflow Determined from Thermal Dust Polarization

Abstract The observational expectation of polarization measurements of thermal dust radiation is investigated to find information on molecular outflows based on magnetohydrodynamical (MHD) and radiation-transfer simulations. There are two major proposed models for driving of molecular outflows: (1) molecular gas is accelerated by magnetic pressure gradient or magnetocentrifugal wind mechanism before the magnetic field and molecular gas are decoupled, (2) the linear momentum of a highly collimated jet is transferred to the ambient molecular gas. In order to distinguish between these two models, it is crucial to observe the configuration of the magnetic field. An observation of a toroidal magnetic field would be strong evidence that the first model is appropriate. We calculated the polarization distribution of thermal dust radiation due to the alignment of dust grains along the magnetic field using molecular outflow data obtained from two-dimensional axisymmetric MHD simulations. An asymmetric distribution around the $z$-axis is characteristic for magnetic fields composed of both poloidal and toroidal components. We found that the outflow has a low polarization degree compared with the envelope and that the envelope and outflow have different polarization directions (B-vector); i.e., the magnetic field within the envelope is parallel to the global magnetic field lines while the magnetic field of the outflow is perpendicular to it. We, then, demonstrated that the point-symmetric (rather than axisymmetric) distributions of low polarization regions indicate that molecular outflows are likely to be magnetically driven. Observations of this polarization distribution with tools such as ALMA would confirm the origin of the molecular outflow.

Thermal Microwave Radiation for Subsurface Absolute Temperature Measurement

Problems related to thermal radiation of human bodies in the microwave range are presented in the paper from medical diagnosis point of view. The paper reviews physical principles of thermal radiation measurement at microwave frequencies. A design of a modulation type radiometer with both zero reading and compensation of influence of the reflectivity is presented in the paper. On the base of this design, requirements for absolute temperature measurement conditions in the lossy and homogeneous medium were found. It is worth noting that these demands do not need any limitations for environmental parameters, especially for their stability during measurement (ambient temperature stability). At the end, experimental results of the measurements carried out with the use of the microwave radiometer operating in the 1.5 GHz band are shown.

Optimal parameterization of the spectra of outgoing thermal radiation with the data of the IKFS-2 spaceborne IR sensing device taken as an example

From the ensemble of the calculated spectra of the outgoing thermal radiation in the 660- to 2010-cm−1 range (2311 realizations) simulating global measurements by the IKFS-2 spaceborne device, the informativeness of the measurements of the outgoing thermal radiation has been analyzed in terms of Kozlov’s data volume, the degrees of freedom, and the Shannon information gain. In the entire spectral range (660–2010 cm−1), there are 106 independent parameters in the measurements of the outgoing radiation. The accuracy of the optimal parameterization of the spectral behavior of the radiation based on the radiation resolution into eigenvectors of the spectral covariance matrix has been analyzed. It is shown that to reach an rms error of the parameterization comparable with the random measurement noise for different spectral regions, it is sufficient to use from 20 to 50 first eigenvectors.