Spectral Characteristics Of Radiation Research Articles

Spectral radiation characteristics in semi-coke jet flame for energy utilization

To provide a reference for research and design of the photo-thermal energy cascaded utilization system of fuel combustion, this paper studies the spectral radiation characteristics of the semi-coke jet flame from the perspective of radiative energy utilization. Based on a self-built Hencken flat-flame burner, the spectral radiation characteristics of the semi-coke flame are measured under O2/N2 and O2/CO2 atmospheres using an optical fiber spectrometer. In particular, the spectral radiative exergy characteristics are analyzed based on the second law of thermodynamics. It is found that the intensity of radiative energy and exergy increase, as does the proportion of spectral radiation below the wavelength of 3 μm, with the oxygen ratio and temperature under the experimental conditions. There is little difference between O2/CO2 and O2/N2 atmospheres in the effect on the spectral radiation characteristics. The spectral proportion in the waveband below 1.1 μm is about 7%, while that is over 60% in the waveband of 1.1–3 μm, showing considerable utilization potential. The proportion characteristics of spectral radiation exergy are similar to that of spectral radiation energy in the total spectrum. The spectral radiation in the waveband below 3 μm has higher energy quality because its exergy-to-energy ratio could reach between 76% and 85%. The main factor affecting the radiation exergy is temperature, whereas the influence of the waveband is not obvious. One-dimensional calculation cases of radiation transfer constructed according to the combustion characteristics can well simulate the proportion of spectral radiation. Further studies could adopt numerical simulation as a reasonable supplementary.

An improved collision - radiation model of the OH spectrum in the ultraviolet band

In order to calculate the spectral radiation characteristics of OH(A2∑) molecules more accurately, an improved collision-radiation (C-R) model is proposed to determine the excited states OH(A) number density. The six-components air model (CO, CO2, H2, H2O, N2, and O2) instead of the two-components air model (N2 and O2) are used as other plume products in the excitation/de-excitation radiation reaction, and the rate of the four reactions are modified to improve the accuracy and applicability of the number density. Effects of temperature and other plume products on the number density of excited states are analyzed in the experiment, and the spectral radiation characteristics of OH(A) can be obtained by using this improved C-R model. Results of these calculations are then compared with other series of experimental data of exhaust plume and shock layer, the results show that both the original model and the improved model can be used to calculate the radiation characteristics in shock layer, however, due to the great error, the original model not apply to calculation of the OH(A) number density in exhaust plume, and the result of the improved model is in good agreement with the Atlas experimental data. As the vibrational-rotational level distribution number density has a close relationship with radiative spectral characteristics, a more focused OH(A) particle number density model will be more helpful to the hypersonic target detection and recognition.

Spectral radiative energy and exergy analysis of oxy-fuel gaseous media in one-dimensional furnace cases

In this study, the spectral radiation characteristics of gaseous media during oxy-fuel combustion are investigated using the heat transfer method from the perspective of energy quality and utilization. Based on the gas radiation model and radiation thermodynamic theory, the effects of different parameters on the spectral radiation proportion and total radiation flux are investigated in one-dimensional furnace cases, including the temperature, pressure, and molar ratio. Based on the results of radiative energy and exergy, a model was established to predict the spectral radiative exergy characteristics of gas flame in furnace. It is found that temperature is the dominant influencing factor. At a flame average temperature of 1600 K, the proportion of spectral radiation in the waveband of 0–2 μm accounts for 26.8%. The high-temperature and short-wavelength spectral radiation has a high exergy-to-energy ratio. Increases in the total pressure and molar ratio increase the total radiative energy, exergy, and short-wavelength radiation ratio, whereas the total pressure has less effect when the pressure is greater than 5 bar. The proposed model for predicting radiative exergy has an error of only about 1% within the flame temperature range. This study provides a reference for future research on the frequency-splitting cascade utilization and management of radiation energy in fuel combustion.

Spectral Characteristics of Electromagnetic Radiation of Cloud Discharges Trigged by Model Hydrometeors in an Artificial Thunderstorm Cloud

Spectral Characteristics of Electromagnetic Radiation of Cloud Discharges Trigged by Model Hydrometeors in an Artificial Thunderstorm Cloud

Air target reference spectrum selection based on characteristic wavelengths extracted by successive projections algorithm

Possessing certain spectral radiation characteristics in a relatively stable state, the air target can be identified according to its spectrum. At first, with the simulation model of air target spectral radiation, the spectral radiance was calculated. Secondly, successive projections algorithm was applied to extract the characteristic wavelengths from the simulation spectral data to reduce required data while retaining a certain accuracy. At last, the hybrid spectral similarity measure named SID (TAN) was involved in comparing the spectral radiation characteristics of different flying heights and flying time in 3-5 μm band and 8-14 μm band called dual atmospheric windows due to its stronger discrimination capability. The result shows that flying heights exert a greater effect on target spectral radiation characteristics than flying time. Meanwhile, changes in 3-5 μm band are more obvious than in 8-14 μm band. Therefore, aiming to improve the recognition accuracy, more factors are supposed to be considered in 3-5 μm band than in 8-14 μm. Compared with flying time, it is recommended to select more spectra of various flying heights as reference spectrum.

МОДЕЛЬ ОБЧИСЛЕННЯ РІВНІВ ЗВУКУ ШУМУ ВІД КОМПРЕСОРНИХ СТАНЦІЙ ДЛЯ ОБГРУНТУВАННЯ ГРАНИЦЬ САНІТАРНО-ЗАХИСНОЇ ЗОНИ

This article is devoted to the study of sound levels for noise from a gas turbine plant and technological equipment of a compressor station in everyday operation, in order to assess the sustainability of the conditions of sanitary protection zones around the compressor station and in order to protect the population living near the compressor station. The main purpose of the study is to assess the compliance of the sizes of sanitary protection zones in terms of noise load on environment. The main source of noise at compressor gas-pumping stations is determined by the noise regime at the industrial site, in addition to auxiliary equipment; include gas-pumping devices, systems of technological gas discharge from the blower circuits, fuel and starting gas of gas-pumping devices. The dependence of the noise conditions at the production site and in the environment on the sound power level of gas-pumping apparatuses, the installed power of gas-turbine plants, the sound power of the turbocompressor, service life of gas-pumping apparatuses, the number of simultaneously operating gas-pumping apparatuses, the characteristics of production premises, the design of the gas-pumping apparatuses, the state of means of noise absorption of gas-pumping apparatuses. In gas turbine installations of compressor stations, intense noise occurs in the air intake and exhaust systems, in the cooling system fan, in the turbomachine housing and in the generator. To calculate the sound levels at a separate point, depending on the distance to the noise source, a model was used taking into account the effects of sound wave propagation in atmospheric air and the characteristics of the noise source, such as: directivity and spectral characteristics of radiation, the height of the source above the surface; distance from the source to the point of determining the sound level; absorption of sound in atmospheric air, depends on the frequency and parameters of the state of the atmosphere; the effect of the influence of the earth; weather effects and others. The methodology of the standard and the international method CONCAW were used based on the results of calculating sound levels at the border of the sanitary protection zone at the compressor station. The calculation results, for standard atmospheric conditions, according to the international CONCAW method indicate that at a distance of 700 m from the sound source, the sound propagation will be 50.0 dBA, which coincides with the calculation results using the standard method and also exceeds the night noise standard by 5 dBA for conditions in the residential area. Development even when only one gas compressor is in operation, which proves the relevance of studying the environmental risks of compressor stations. KEY WORDS: NOISE, ENVIRONMENTAL RISKS, NOISE SOURCE, COMPRESSOR STATIONS, GAS PUMPING UNIT, GAS PUMPING APPARATUS, SOUND.

Fast method for computer simulation of luminescence characteristics of multilayer biological tissues with embedded luminescent nanoparticles

We report a fast and computationally stable method for computer simulation of optical properties of layered scattering systems containing luminescent layers. The method is based on the solution of one-dimensional scalar radiative transfer equations and makes it possible to calculate spectral and angular characteristics of luminescent radiation emerging from the system under various conditions of luminescence excitation. The method is used to estimate the parameters necessary for determining temperature in subcutaneous layers from luminescence spectra of up-conversion nanoparticles embedded in these layers during transcutaneous optical probing.

Spectral energy characteristics of radiation in oxy-coal combustion for energy utilization

In this paper, the radiative energy characteristics, especially the spectral distribution characteristics, of the oxy-fuel combustion of pulverized coal are studied from the perspective of radiative energy utilization. Based on a modified tube furnace test platform, the radiative energy flux and spectral distribution of oxy-fuel combustion for three typical Chinese coals under O2/N2 and O2/CO2 atmospheres in the temperature range of 600–1000 °C are measured online using radiative heat flux sensors. In particular, the radiative exergy and its spectral distribution characteristics are analyzed based on the second law of thermodynamics. It is found that the intensity of the radiative energy and exergy increase, as does the proportion of spectral radiation below the wavelength of 4.1 μm, with the increase of the oxygen ratio and combustion temperature under the experimental conditions. In contrast, different atmospheres are found to have little effect on the radiation characteristics. One-dimensional calculation cases of media radiation transfer constructed according to the combustion characteristics can better reveal the proportional characteristics of the spectral radiation. The results provide a reference for research on the cascade conversion and management of photo-thermal energy in fuel combustion.

EMISSION CHARACTERISTICS OF GAS DISCHARGE PLASMA ON MIXTURES OF CADMIUM DIODIDE VAPOR, HELIUM AND XENON

The results of studying the spectral, integral, and resource characteristics of gas-discharge plasma radiation on multicomponent mixtures (cadmium diiodide with helium and xenon atoms) are presented. The creation of a gasdischarge plasma and the excitation of the components of the working mixture were carried out by a pulse-periodic (pulse repetition rate of 18…20 kHz, pulse duration ~ 150 ns) barrier discharge. Radiation in the visible spectrum of exciplex molecules of cadmium monoiodide, cadmium atoms, xenon was detected. The regularities in changes in the emission characteristics of the plasma are established depending on the repetition rate of the pump pulses, the component and quantitative composition of the mixtures. Research data is of interest for creating a gas-discharge source that radiates simultaneously in the violet, green, red, and infrared spectral ranges.

Spectral radiate characteristics of gas phase combustion product of energetic fules

The results of long-term experimental studies of the spectral radiation characteristics of the gas phase of the combustion products, performed on measuring complexes of medium and high spectral resolution in the temperature range 200-2800 K, are carried out. The spectral transmission functions are parametrized by the two-parameter equivalent mass method, which makes it possible to solve radiation heat transfer problems in structurally inhomogeneous high - temperature multicomponent gas environments of the products of combustion of energy fuels of the combustion chambers of energy units to generate thermal and electrical energy. The results of modeling radiation heat transfer in combustion chambers and heat exchangers of multi - chamber furnaces with hearth multi-row burner devices and bottom feeding of solid fuel combustion products into a radiation heat exchanger from cyclone furnaces are discussed.

Spectroscopic diagnostics of a high-frequency dielectric barrier discharge of atmospheric pressure in mixtures of cadmium diiodide vapor with neon and small additions of xenon

Diagnostics of the emission spectra of a gas-discharge plasma of a barrier discharge of atmospheric pressure in mixtures of cadmium diiodide vapor with neon and small additions of xenon is carried out. A gas-discharge plasma was created and the components of the working mixture were excited by a high-frequency barrier discharge at a sinusoidal voltage pulse repetition rate of up to 140 kHz. Emission of exciplex molecules of cadmium monoiodide with a maximum emission at a wavelength of λ = 655 nm and xenon iodide with a maximum of radiation at wavelengths λ = 253 and λ = 320 nm, excimer molecules of iodine, lines of atoms of cadmium, iodine, neon and xenon was revealed. It was found that at temperatures of the mixtures under study above 150 0C, the predominance of radiation from exciplex molecules of cadmium monoiodide is observed. The reason for the increased brightness of the emission of exciplex molecules of cadmium monoiodide in mixtures of cadmium diiodide vapor with neon and xenon additive is established. The regularities in the spectral characteristics of radiation in the mixtures under study are discussed. A high-frequency barrier discharge of atmospheric pressure in mixtures of cadmium diiodide vapor with neon and xenon is of interest for creating a multi-wavelength excilamp in the UV and visible spectral ranges

Absolute radiometric calibration of Fengyun-3D Medium Resolution Spectral Imager-II and radiation characteristics analysis

This study analyzes the response changes of the Medium Resolution Spectral Imager II (MERSI-II), which is an optical instrument on the Fengyun-3D satellite, during different periods since liftoff. The study was based on the Dunhuang radiometric calibration site. The solar reflective channels, assessed using the reflectance-based method, showed a degradation of MERSI-II. The degradation rate of change was found to be higher in the beginning of the mission and to be decreasing with time. The latest calibration results show that the decrease in instrument response between 440 and 900 nm in the near-infrared band was relatively small compared to the previous official calibration coefficient, with an average attenuation rate of ∼5.3 % . It was observed that the MERSI-II shortwave channel had a large attenuation of 21%, especially in the 412 nm band. The calibration method and parameter processing of the reflectance-based method are introduced in detail. The accuracy of the calibration process was tested using Moderate Resolution Imaging Spectroradiometer, an internationally recognized high-precision satellite instrument, which determined the calibration error to be <4 % . The experimental results contribute to the improvement in the accuracy of satellite observation and the design of subsequent equipment.

Mass-Independent Sulfur Isotope Fractionation in the Photochemical SO2 Processes under the UV Radiation of Different Wave Length

A series of photochemical experiments with sulfur dioxide were carried out using a xenon lamp (λ > 200 nm), a low-pressure mercury lamp (λ = 184.9 and 253.7 nm), and an UP-213 laser system (λ = 213 nm) as light sources. Based on the isotope data obtained for elemental sulfur (the end product of SO2 photolysis), we revealed specifics in correlations between δ34S, ∆33S, and ∆36S values depending on the spectral characteristics of the incident radiation. Our studies showed that the Archean Δ33S/δ34S and Δ36S/Δ33S ratios could be reproduced in the SO2 photolysis experiments by combining spectral composition of the radiation, the intensity of the spectral components, and the partial pressure of SO2. The results of the experiments suggest that the UV radiation with wavelengths less than 200 nm was a determining factor in the production of sulfur isotopic anomalies in the Archean atmosphere.

Analysis of electromagnetic radiation spectrum during the explosion of energetic materials

In order to provide effective reference data for the equivalent experiment of electromagnetic environment adaptability of electric explosive devices, the electromagnetic radiation generated during the explosion of energetic materials is measured. The spectral characteristics of the electromagnetic radiation during the explosion of energetic materials are obtained by processing the data by means of signal noise reduction, windowed Fourier transform and dynamic spectrum analysis. The results indicate that the spectrum of electromagnetic signal during the explosion of energetic materials shows large changes mainly in the frequency band of 0-100MHz, of which the energy change in the low frequency band below 50 MHz is the most obvious; the distance from the explosion center has an obvious influence on the spectrum distribution of electromagnetic signal, where the closer the test point is to the explosion center, the wider the spectrum distribution of electromagnetic signal is and the stronger the energy is; differences in electromagnetic frequency distribution in different directions reflect the uneven and dispersed propagation of electromagnetic radiation.

Influence of spectral characteristics of the Earth's surface radiation on the greenhouse effect: Principles and mechanisms

Enhanced greenhouse effects by anthropogenic emissions of greenhouse gases (GHGs) resulted in global warming since the Industrial Revolution. However, the influence of the spectral characteristics of the Earth's surface radiation on the greenhouse effect has not been completely explored. This work uses the surface temperature as the variable of model and investigates the response mechanism of the greenhouse effect. According to the GHGs' different selective spectral absorption of earth's infrared radiation (IR) band and the distribution characteristic of spectral radiant intensity with the temperature increases, some quantified analysis shows that the greenhouse effect is highly dependent on two factors: the radiation intensity enhancement (RIE) and the spectral absorption enhancement (SAE). RIE is determined by the spectral radiant intensity of earth's IR while SAE represents the GHGs' spectral absorption change under different wavelength. As the results show, RIE always enhances the greenhouse effect, while SAE, as a result of the spectral shift in the Earth's radiant energy, can enhance or weaken the greenhouse effect depending on the positive or negative total SAE integrated over the entire spectral region. The quantified data of this work also explain the reason why greenhouse effect has greater impact on extreme cold areas from the aspect of spectral characteristics: when the surface temperature drops below −20 °C, SAE of CO2 has an enhancing effect, so that both RIE and SAE exert positive influences with the temperature increase in the polar region for its extremely low surface temperature, which doubly enhances the global warming.

Arrangement structure of carbon nanofiber with excellent spectral radiation characteristics

Abstract To explore the spectral radiation characteristics of carbon nanofibers, a finite-difference time-domain method has been applied to study and calculate the scattering/absorption factors of carbon nanofibers with various arrangements, while the filler contents are 61.15%, 53.81%, 48.92%, 44.03% and 39.13% in the spectrum band of 2.5–15 µm. The effects of the nanofiber content, 2D/3D random arrangement and nanofiber radius on scattering/absorption characteristics have been analyzed. The analytical results show that the spectral radiation characteristics of carbon nanofibers have been significantly increased with an increase in the filler content. When the nanofiber content reduced to 48.92%, the random arrangement structure of carbon nanofiber plays an essential role in determining the spectral radiation characteristics. Analytical results prove that the prediction accuracy has been significantly improved by 30.12% by sing the 3D random arrangement model than by using the 2D uniform arrangement model. This study proposed a 3D model to predict the spectral radiation characteristics of carbon nanofibers and their aggregates in engineering nanocomposites.

Overview of electrical power models for concentrated photovoltaic systems and development of a new operational model with easily accessible inputs

The utilization of multi-junction solar cells with high efficiency is still not widespread for terrestrial power applications. These solar cells, composed by several material layers, reach high efficiencies but its cost is expensive, more of 100 higher than classical silicon solar cells. Thus, one solution consists to use reduced sizing solar cells associated with optics mounted on solar tracker to concentrate the solar beam. Numerous meteorological parameters such as beam solar irradiance, ambient temperature and air mass and especially spectral characteristics of sun radiation are involved in the conversion process and are generally used as inputs in power models. Several models from literature, different by their form and by the number and type of input variables, are presented; based on this state-of-art, some similar models are selected and tested on two experimental CPV systems located on two different sites, Ajaccio and Le Bourget du Lac. Then, an operational model of electrical power using inputs easily measured and available for a solar CPV plant operator is developed. It could be used as a decision-aided tool for investors in providing an estimation of the energy production capacity of the CPV systems on the future implantation site. This established model based on data measured on the CPV system in Ajaccio estimates the produced power with a root mean square error of about 5% on the two sites using only a reduced number of inputs.

Numerically resolved line by line radiation spectrum of large kerosene pool fires

A numerical model is presented for spectral characteristics of radiation coming from a pool fire flame. The case studies are 1.75 m × 1.75 m and 2.5 m × 2.5 m Kerosene pool fires. Transient heat and mass transfer of the system was solved using a CFD model of a 4 m × 4 m × 5 m rectangular domain built in Fire Dynamic Simulator (FDS) with LES of turbulence and a two-step combustion reaction. Transient profiles of gas compositions, soot concentration and temperature along a line of sight of an imaginary sensor were collected from the CFD simulations, and instantaneous solutions of the thermal radiation along the line were calculated using high-resolution LBL spectral absorption profiles of combustion gases together with a model for soot absorption coefficient, based on spectrally dependant complex index of refraction. The transient spectra, consisting of numerous instantaneous intensity solutions, were then averaged and compared against the similar experimentally measured data. The line of sight and other settings of the model were carefully checked to be consistent with the experiments performed for the same system. The modelling results revealed the strong absorption effect of cold atmospheric gases while the emission peak of hot CO2 at ~2200 cm−1 in fire is still quite distinguishable from the spectral profile of hot blackbody even at 23 m away from the centre of the flame. This emission peak can be therefore used for detection of the fire. The spectral changes of the spectrum are explained and a sensitivity analysis is performed to study the effects of the sensor's distance from the pool, pool size, and modelling and operational conditions, such as relative humidity and radiative fraction.

The modular equipment for training based on the semiconductor lasers

The description is given of the study and research a modular-type training complex for studying the radiation of semiconductor lasers generated in the region of 400 – 950 nm. Structurally, the complex consists of emitter modules (there are 8 of them in the presented set, but in principle their number is not limited by anything), power and control modules, registration modules, and some additional measuring equipment to provide research on the energy, spectral, spatial, polarization and dynamic characteristics of the output radiation. The modular structure provides high variability of the complex and allows you to implement (in the presented version) more than 40 laboratory works, and also allows students to get skills in working with modern equipment and different data processing methods. This complex is focused on educational activities, but on its basis it is possible to carry out research work up to the second stage of higher education. A number of laboratory works based on the use of the complex have been tested at the department of laser physics and spectroscopy of the physics faculty of the Belarusian State University.

Spectrally Selective Transformations of Solar Radiation by Retinal Photoreceptors in the Control of the Circadian Rhythm of the Human Body throughout an 11-Year Cycle of Solar Activity

Abstract—The round-the-day effect of solar radiation on photoreceptors of the retina of the eye and its role in the control of the circadian rhythm of the human body within an arbitrary 11-year cycle of solar activity are considered. Processed data describing the variation of the spectral and energy characteristics of solar radiation that reach the Earth’s surface over a solar activity cycle are given. On this basis, a generalized analytical expression has been obtained that models the spectrally selective processing of the sum of the direct and diffuse components of solar radiation by retinal rods and blue-sensitive (S type) cones. The obtained expression allows consideration of separate spectrally selective processing of the direct and diffuse components of solar radiation by rods and S cones of retina, including the case of a catastrophic lesion of one of the neuronal paths that connect rods or S cones with suprachiasmatic hypothalamus nuclei. It is shown that the effective spectrum obtained as a result of spectral selection of the components of solar radiation that is used to control the circadian activity of the human body is determined solely by the spectral sensitivity of rods and S cones. The effective spectrum does not depend on daily variations in the spectrum of solar radiation as the angular elevation of the Sun varies; the daily energy characteristics of the effective spectrum, which vary within each solar activity cycle, retain their dependence on the Sun’s elevation in the daytime and on the current phase of the solar activity cycle. Significant changes in the characteristics of solar radiation within the cycle of solar activity infer that it is necessary to take them into account in studying and modeling the control processes of human circadian activity driven by solar radiation.