Normal Emission Research Articles

Simultaneous measurement of normal spectral emissivity and temperature of materials with low thermal conductivity

This study develops a measurement system and a method for measuring the normal spectral emissivity and temperature of low thermal conductivity materials at high temperatures. A self-design heating device using a synergistic heating treatment including a high-power laser and a radiation heating cavity is introduced, and a Fourier transform infrared spectrometer is utilized to measure the radiation signal of sample. Based on the temperature hypothesis model, which considers normal spectral emissivity keeps constant within small temperature difference less than 10.0 K, a method is proposed for realizing the inversion of normal spectral emissivity and temperature with the multispectral radiation signal. A genetic algorithm-based technique with big mutations is used to estimate the normal spectral emissivity and temperature of sample at high temperatures. The variation of blackbody radiation signals with the blackbody radiance is analyzed to verify the linearity for the detector of FTIR spectrometer. The apparent normal spectral emissivity of an alumina ceramic fiber is determined in the spectral range of 2.5–25.0 μm at 673–1273 K. Furthermore, the uniformity of temperature distribution on the sample surface and inside the sample is numerically evaluated. The standard uncertainty in the experiment at 1273 K is less than 4.0 % in the investigated bands.

The ST component in the Si 2p photoemission spectrum from H-terminated and oxidized Si (001) surfaces

One doublet is usually employed to fit the Si0 substrate species in the Si 2p photoemission spectra from Si (001) H-terminated (after piranha treatment) and oxidized surfaces. However, there is a second substrate-top component (ST) with a binding energy of 0.3 eV higher than the bulk component; its intensity varies from ∼10% at normal emission (i.e., 90° from the surface) to ∼20% at 35°. It is present even for oxidized surfaces and does not correspond to any of the suboxide species. It corresponds to the first layers of the substrate and is responsible for the decrease in the signal dip between the two S–O branches of the Si 2p spectra for glancing electron takeoff angles. Although it is resolvable for monochromatized sources, the ST component is absent in the literature on Si 2p spectra.

Optical reflection characteristic-based emissivity analysis of a pyramid array flat-plate blackbody for remote sensor calibration.

The flat-plate blackbody (FPB) is the core device in infrared remote sensing radiometric calibration for providing accurate infrared radiation energy. The emissivity of an FPB is an important parameter that directly affects calibration accuracy. This paper uses a pyramid array structure based on the regulated optical reflection characteristics to analyze the FPB's emissivity quantitatively. The analysis is accomplished by performing emissivity simulations based on the Monte Carlo method. The effects of specular reflection (SR), near-specular reflection (NSR), and diffuse reflection (DR) on the emissivity of an FPB with pyramid arrays are analyzed. In addition, various patterns of normal emissivity, small-angle directional emissivity, and emissivity uniformity are examined under different reflection characteristics. Further, the blackbodies with the NSR and DR are fabricated and tested experimentally. The experimental results show a good agreement with the corresponding simulation results. The emissivity of the FPB with the NSR can reach 0.996 in the 8-14 µm waveband. Finally, the emissivity uniformity of FPB samples at all tested positions and angles is better than 0.005 and 0.002, respectively. The standard uncertainty of experimental measurement of waveband emissivity and spectral emissivity are 0.47% and 0.38% respectively, and the simulation uncertainty is 0.10%.

Hearing impairment in patients with alopecia areata.

Background Alopecia areata is an autoimmune disease that damages hair follicles and follicular melanocytes can be involved in the autoimmune process. Therefore, similar to vitiligo, there may be a relationship between sensorineural hearing loss and alopecia areata. Aims/objectives This study aimed to investigate potential hearing impairments in patients with alopecia areata. Methods A total of 42 subjects with alopecia areata and 42 healthy individuals enrolled in this cross-sectional study. The hearing was evaluated by vestibular evoked myogenic potential, otoacoustic emission and pure tone audiometry tests in the patients and control subjects. Results A normal otoacoustic emission was reported in 59.5% and 100% of subjects with alopecia areata and the controls, respectively (P = 0.02). Higher speech recognition thresholds (P = 0.02) and speech discrimination scores were reported more in subjects with alopecia areata than in controls (P < 0.001); however, the most comfortable level of speech was not significantly different between the groups (P = 0.06). The greatest increase in the hearing threshold was recorded at a frequency of 8000 Hz, while at frequencies of 500 and 1000 Hz, the patients and controls did not significantly differ (P > 0.05). About 6 (14.3%) and 2 (4.8%) of patients with unilateral and bilateral involvement, respectively, demonstrated no vestibular evoked myogenic potential response in the alopecia areata group. The patients and controls did not significantly differ in terms of amplitudes of the vestibular evoked myogenic potential test (P = 0.097). Limitation Small sample size and qualitative measurement of otoacoustic emission were limitations of our study. Conclusion Hearing loss was more common in alopecia areata patients than in healthy individuals. Follicular melanocytes may be involved in the alopecia areata inflammatory process, and destroying melanocytes may impact hearing function in the inner ear. However, there was no significant relationship between the duration and severity of alopecia areata and hearing loss.

Normal spectral emissivity characteristics of tungsten in the mid-infrared region

Tungsten is an important material constituting the first wall of the Experimental Advanced Superconducting Tokamak due to its excellent corrosion resistance. The temperature distribution of the first wall during the discharge process are the key to ensuring the safe and stable operation of the EAST. Therefore, it is necessary to explore the dependence of material emissivity on temperature and wavelength for improving temperature measurement accuracy. This work quantitatively explores the normal spectral emissivity of tungsten within the 3 μm to 5 μm in the temperature range between 100°C and 500°C based on the Fourier transform infrared spectrometer. The dependence of emissivity on wavelength and temperature are experimentally analyzed, and the possible functional relationship between the emissivity of tungsten and the surface temperature and the wavelength are established respectively. This work could lay the foundation for the application of multi-wavelength thermometry on temperature measurement of the first wall of the EAST.

Potential application of Eu3+ ion-activated Ca2InTaO6 red phosphor with high thermal stability in WLEDs

The high-temperature solid-phase method synthesized a series of red phosphors Ca2InTaO6: xEu3+. Their most substantial emission peak is at 612 ​nm, FWHM ​= ​8 ​nm, and they can be excited under blue light. Has very excellent thermal stability, still has 77.7% of normal emission intensity at 150 ​°C, and the luminous intensity decreases very slowly between 80 ​°C–150 ​°C. In the high temperature durability test at 120 ​°C and 150 ​°C, the sample can still maintain good luminous intensity for a long time. The WLED was fabricated using fabricated samples in combination with commercial green and blue phosphors; it has Ra ​= ​90.1 and R9 ​= ​83.4. All expected test results prove that this sample is suitable for modern LED lighting.

Effects of a Graphene Heating Device on Fatigue Recovery of Biceps Brachii.

Far-infrared (FIR) is considered to be an ideal method to promote fatigue recovery due to its high permeability and strong radiation. In this paper, we report a flexible and wearable graphene heating device to help fatigue recovery of human exercise by using its high FIR divergence property. This study compares two different fatigue recovery methods, graphene far-infrared heating device hot application and natural recovery, over a 20 min recovery time among the male colleges' exhaustion exercise. Experimental results show that the achieved graphene device holds excellent electro-thermal radiation conversion efficiency of 70% and normal total emissivity of 89%. Moreover, the graphene FIR therapy in our work is more energy-efficient, easy to use, and wearable than traditional fatigue recovery methods. Such an anti-fatigue strategy offers new opportunities for enlarging potential applications of graphene film in body science, athletic training recovery, and wearable devices.

Spectral emissivity measurement of free-falling particle groups

A solar energy receiver is a device that absorbs solar radiation and transfers the generated heat energy to a heat transfer medium. As a heat transfer medium in solar energy receivers, solid particles can safely absorb strong solar radiation flux and achieve a higher operating temperature. Hence, they have attracted considerable research interest. The emissivity of particles is an important parameter in numerical simulation and efficiency analysis of solid particle receivers. However, it is rarely reported, especially for dispersed particles flowing in receivers. In this study, a measurement system for the normal spectral emissivity of free-falling particles is designed and developed. The system is based on the energy method and uses an FTIR spectrometer as a radiation measurement device, which can achieve measurement in the wavelength range of 2.5–16 µm below 800 °C. The emissivity of the sheet SiC material is measured to verify the reliability of the system. The results are in good agreement with the data published in NIST. Furthermore, the effects of the particle material, temperature, and particle group thickness on the particle group emissivity are studied. It is found that the emissivity of gray ceramic sand particles is not sensitive to the temperature, whereas that of alumina ceramic particles is positively correlated with the temperature. The emissivity of the two particles increases rapidly with the release width of the particle group, which is related to the increase in the mass flow rate of the particle group. Finally, uncertainty analysis of the measurement system is performed. The results measured in this paper can provide the original emissivity data for heat transfer simulation and efficiency evaluation in the receiver.

Combined Prediction Model of Gas Concentration Based on Indicators Dynamic Optimization and Bi-LSTMs

In order to accurately predict the gas concentration, find out the gas abnormal emission in advance, and take effective measures to reduce the gas concentration in time, this paper analyzes multivariate monitoring data and proposes a new dynamic combined prediction method of gas concentration. Spearman's rank correlation coefficient is applied for the dynamic optimization of prediction indicators. The time series and spatial topology features of the optimized indicators are extracted and input into the combined prediction model of gas concentration based on indicators dynamic optimization and Bi-LSTMs (Bi-directional Long Short-term Memory), which can predict the gas concentration for the next 30 min. The results show that the other gas concentration, temperature, and humidity indicators are strongly correlated with the gas concentration to be predicted, and Spearman's rank correlation coefficient is up to 0.92 at most. The average R2 of predicted value and real value is 0.965, and the average prediction efficiency R for gas abnormal or normal emission is 79.9%. Compared with the other models, the proposed dynamic optimized indicators combined model is more accurate, and the missing alarm of gas abnormal emission is significantly alleviated, which greatly improves the early alarming accuracy. It can assist the safety monitoring personnel in decision making and has certain significance to improve the safety production efficiency of coal mines.

Chronic stress induced loudness hyperacusis, sound avoidance and auditory cortex hyperactivity

Hyperacusis, a debilitating loudness intolerance disorder, has been linked to chronic stress and adrenal insufficiency. To investigate the role of chronic stress, rats were chronically treated with corticosterone (CORT) stress hormone. Chronic CORT produced behavioral evidence of loudness hyperacusis, sound avoidance hyperacusis, and abnormal temporal integration of loudness. CORT treatment did not disrupt cochlear or brainstem function as reflected by normal distortion product otoacoustic emissions, compound action potentials, acoustic startle reflexex, and auditory brainstem responses. In contrast, the evoked response from the auditory cortex was enhanced up to three fold after CORT treatment. This hyperactivity was associated with a significant increase in glucocorticoid receptors in auditory cortex layers II/III and VI. Basal serum CORT levels remained normal after chronic CORT stress whereas reactive serum CORT levels evoked by acute restraint stress were blunted (reduced) after chronic CORT stress; similar changes were observed after chronic, intense noise stress. Taken together, our results show for the first time that chronic stress can induce hyperacusis and sound avoidance. A model is proposed in which chronic stress creates a subclinical state of adrenal insufficiency that establishes the necessary conditions for inducing hyperacusis.

Integrated Valve Product Fluid Simulation and Test Verification

The integrated valve product’s main function is to electrolytic oxygen generation subsystem to produce hydrogen and oxygen to realize automatic discharge, to maintain the space station astronauts in orbit around in comfort and safety, high reliability, easy maintenance, and the device should be easy replacement of human-computer ergonomics requirements to ensure long-term on-orbit operation station. Based on the above requirements, an integrated valve product based on environmental control and a health protection system is designed. The integrated product includes hydrogen normal and backup emission branches, oxygen normal and backup emission branches. Through fluid simulation and experimental verification, it is verified that the flow rate and other key indicators of the integrated valve product meet the requirements, which has certain reference and guiding significance for the design of similar integrated products in the future.

Emissivity measurements of W/TiAlN/TiAlSiN/TiAlSiON/TiAlSiO -based multilayer spectrally selective absorbers at high temperature

Solar absorber with low infrared emissivity is an important component of the solar thermal system. The major problem of these absorbers has been the high emissivity at high temperatures causing heat loss from the system. One key solution for this issue is to study the emissive characteristics of these absorbers at high temperatures. This paper describes the infrared emissivity of W/TiAlN/TiAlSiN/TiAlSiON/TiAlSiO at elevated temperatures of 100 – 600 °C. The absorber exhibits excellent spectral selectivity with a high absorptance (α) in the solar spectrum (0.25 – 2.5 µm) and low thermal emissivity (ε) in the infrared range (2.5 – 25 µm). Directional spectral emissivity measurements performed between 10 and 80° show an emissivity decrease with the angle for wavelengths below 3.5 µm, followed by an increase in emissivity at higher wavelengths that reaches a maximum at an emission angle of 70 – 80°. The total normal emissivity shows an increase from 0.064 ± 0.016 to 0.216 ± 0.003 when the measured temperature increases from 100 to 600 °C. On the other hand, the total hemispherical emissivity does not show a significant temperature dependence. Microstructural characterizations including grazing incident X-ray diffractogram (GIXRD), scanning electron microscopy (SEM), and energy dispersive X-ray analysis (EDS) confirmed the thermal stability of the sample even after high temperature exposure up to 600 °C during emissivity measurements.

Near-infrared normal spectral emissivity of molten Fe-Ni alloys by electromagnetic heating

The spectral emissivity of molten Fe-Ni alloys is especially critical to analysis the performance and quality of alloy. The near-infrared normal spectral emissivity of molten Fe-Ni alloys was measured at 1000–1600 nm in the temperature range of 1690–1845 K by a self-built measurement apparatus using the electromagnetic heating technology. The measurement apparatus mainly consists of the electromagnetic heating furnace, blackbody, optical fiber spectrometer and colorimetric thermometer. The dependence of near-infrared normal spectral emissivity of Fe-Ni alloys (Ni, Fe10Ni90, Fe30Ni70, Fe50Ni50, Fe70Ni30, Fe90Ni10 and Fe) on wavelength, temperature and composition were systematically investigated. The results show that the emissivity of Fe70Ni30 is higher in the iron-rich area, while the emissivity of Fe30Ni70 is the lowest in the nickel-rich area. Comparison of the measured and simulated results show that the emissivity of molten Fe-Ni alloys is reliable. The emissivity of Fe-Ni alloys provides reliable data for the research of alloys properties.

Clinical significance of atypical 68Ga-DOTATOC prostatic uptake on PET/CT: A ten-year review.

Gallium-68-DOTA-D-Phe1-Try3-Octreotide (68Ga-DOTATOC) is a radiolabeled somatostatin receptor (SSTR) analog that is widely used in the imaging of neuroendocrine tumors (NET). Benign and malignant prostate tumors have been observed to express SSTR. Diffuse symmetric DOTATOC uptake in the prostate is a normal positron emission tomography (PET) finding. The aim of this study was to evaluate the frequency and clinical significance of incidental atypical prostatic uptake in men undergoing 68Ga-DOTATOC PET/computed tomography(CT). A retrospective review of consecutive male patients who underwent 68Ga-DOTATOC PET/CT studies at Aalborg University Hospital, Denmark, from November 2010 to April 2020 was performed. Positron emission tomography/CT reports were searched for text words or phrases indicating incidental atypical prostatic uptake. In the resulting cohort, PET/CT were re-evaluated, and DOTATOC uptake in the prostate gland was categorized as focal, diffuse or mixed. The intensity of the uptake was visually graded using the Krenning visual score. Follow-up was based on all available clinical, biochemical, imaging, and pathology follow-up. A total of 178 male patients underwent 193 68Ga-DOTATOC PET/CT scans. Incidental atypical uptake of 68Ga-DOTATOC on PET/CT in the prostatic bed was observed in eight patients (4.5%) (mean age 67 years, range 58-85 years). Six patients (75%) had diffuse uptake; two (25%) patients had focal uptake. Four patients out of eight with incidental findings (50%) had uptake less than or equal to that of the liver (Krenning score 2); four patients (50%) had uptake greater than that of the liver (score 3). All patients had measurements of serum prostate-specific antigen and were referred for urological evaluation. Five patients (62%) underwent a transrectal ultrasound, and three required a biopsy of the prostate. No cases of prostate malignancy (including prostatic cancer) were diagnosed. During a 10-year period, we found that 4.5% of men exhibited prostate incidentalomas on 68Ga-DOTATOC PET/CT. No malignancy was found in the prostate in this population. Our data indicate absent malignancy among incidental 68Ga-DOTATOC findings in the prostate.

Measurement of the Normal Spectral Emissivity of Molten Oxide Using an Electromagnetically Levitated Complex Droplet of Molten Oxide and Liquid Fe

We proposed the determination method of the normal spectral emissivity of molten oxides using a combination of immiscible molten oxides and liquid metals. We can determine the normal spectral emissivity of molten oxide from the ratio of the normal spectral radiance of molten oxides andliquid metals, using a commercially available pyrometer combined with an electromagnetic levitation system. In the present study, we measured the normal spectral emissivity of a molten oxide sample from SiO2-CaOFeO (SCF) ternary system and FeO using liquid Fe as the reference liquid metal. The normal spectral emissivity of the molten SCF sample with the composition of SiO2:CaO:FeO = 20:20:60 mass % was determined to be 0.78±0.01 and that of molten FeO to be 0.68 ± 0.03. Based on these results, we have discussed the relationship between the normal spectral emissivity and the electrical conductivity of molten oxides.

Normal spectral emissivity and heat capacity of Pd–Fe melts measured at constant pressure under electromagnetic levitation with a static magnetic field

The normal spectral emissivity at 807 and 940 nm and heat capacity at constant pressure of Pd–Fe melts were measured under electromagnetic levitation with a static magnetic field. The samples were made of Fe of mass purity 99.9985%. The present emissivity of Fe melts was relatively low compared with previously reported data using Fe with purity lower than 99.95% mass purity. The spectral emission of the Fe melts was analyzed using their normal spectral emissivity obtained from the Drude model. The excess heat capacity of Pd–Fe melts was evaluated from the measured heat capacity of Pd–Fe melts. Applying the Lupis–Elliot rule, we concluded from the obtained excess heat capacity that the enthalpy of mixing and excess entropy of the Pd–Fe melts should be negative. The composition dependence of the enthalpy of mixing, excess entropy, and excess Gibbs energy of Pd–Fe melts were evaluated using data obtained in this study and the literature.

Spectral emissivity of transition metals of the X group in the melting point region

An experimental study of the normal spectral emissivity of technical nickel, palladium and platinum in the solid polished and liquid phases near the melting points was carried out by the radiation method. The emission measurement was recorded by the bandwidth of the applied narrowband filters. The dependence of metal emission on the wavelength in the range of the radiation spectrum 0.26-10.6 μm is obtained. A comparative analysis with the literature data of other authors is carried out. A theoretical calculation of the emission is given according to the classical electromagnetic theory Hagen's formula and Rubens. Keywords: normal spectral emissivity, melting range, nickel, palladium, platinum, wavelength.

Photocathode performance characterisation of ultra-thin MgO films on polycrystalline copper

The performance expected from the next generation of electron accelerators is driving research into photocathode technology as this fundamentally limits the achievable beam quality. The performance characteristics of a photocathode are most notably: normalised emittance, brightness and energy spread. Ultra–thin oxide films on metal substrates have been shown to lower the work function (WF) of the surface, enhancing commonly utilised metal photocathodes, potentially improving lifetime and performance characteristics.We present the characterisation of two MgO/Cu photocathodes grown at Daresbury. The surface properties such as: surface roughness, elemental composition and WF, have been studied using atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). The photoemissive properties have been characterised with quantum efficiency (QE) measurements at 266 nm. Additionally, we measure the Transverse Energy Distribution Curves (TEDC) for these photocathodes under illumination at various wavelengths using ASTeC’s Transverse Energy Spread Spectrometer (TESS) and extract the Mean Transverse Energy (MTE).

Спектральная излучательная способность переходных металлов X группы в области точки плавления

An experimental study of the normal spectral emissivity of technical nickel, palladium and platinum in the solid polished and liquid phases near the melting points was carried out by the radiation method. The emission measurement was recorded by the bandwidth of the applied narrowband filters. The dependence of metal emission on the wavelength in the range of the radiation spectrum 0.26−10.6 µm is obtained. A comparative analysis with the literature data of other authors is carried out. A theoretical calculation of the emission is given according to the classical electromagnetic theory — Hagen 's formula and Rubens.

Apparent normal spectral emissivity of TBC(ZrO2)-coated TC4 alloy

Apparent normal spectral emissivity of TBC(ZrO2)-coated TC4 alloy