Temat: radiative transfer - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Accretion and structure of radiating disks
Autorzy:: Mach, Patryk
Malec, Edward
Dostawca treści:: Repozytorium Uniwersytetu Jagiellońskiego

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Skocz do pozycji: 2.

Tytuł:: Radiative Transfer Model parametrization for simulating the reflectance of meadow vegetation
Autorzy:: Jarocińska, Anna M.
Tematy:: Meadows
spectral reflectance
Radiative Transfer Model
PROSAIL; Pokaż więcej
Wydawca:: Uniwersytet Warszawski. Wydział Geografii i Studiów Regionalnych
Powiązania:: https://bibliotekanauki.pl/articles/2037408.pdf Link otwiera się w nowym oknie
Opis:: Natural vegetation is complex and its reflectance is not easy to model. The aim of this study was to adjust the Radiative Transfer Model parameters for modelling the reflectance of heterogeneous meadows and evaluate its accuracy dependent on the vegetation characteristics. PROSAIL input parameters and reference spectra were collected during field measurements. Two different datasets were created: in the first, the input parameters were modelled using only field measurements; in the second, three input parameters were adjusted to minimize the differences between modelled and measured spectra. Reflectance was modelled using two datasets and then verified based on field reflectance using the RMSE. The average RMSE for the first dataset was equal to 0.1058, the second was 0.0362. The accuracy of the simulated spectra was analysed dependent on the value of the biophysical parameters. Better results were obtained for meadows with higher biomass value, greater LAI and lower water content.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Modelowanie charakterystyk spektralnych heterogenicznych zbiorowisk trawiastych przy użyciu modelu transferu promieniowania
Simulating spectrum for heterogeneous meadows using a Radiative Transfer Model
Autorzy:: Jarocińska, A.
Tematy:: model
transfer promieniowania
łąki
PROSPECT
Radiative Transfer Model
meadows; Pokaż więcej
Wydawca:: Polskie Towarzystwo Geograficzne
Powiązania:: https://bibliotekanauki.pl/articles/132270.pdf Link otwiera się w nowym oknie
Opis:: Meadows are important ecosystems and should be protected. Also, in Poland organic agriculture and farming, where crops from meadows are used, is getting more popular. That is why meadows monitoring and predicting crops is important issue. Much information can be calculated from spectrum of plants and that is why remote sensing data are very useful tool. Two approaches are used to calculate biophysical variables: statistical and modelling. In statistical, values from field measurements have to be compared with images. In modelling, radiative transfer models are used. RTM are physical models based on the fundamental equation of radiative transfer. After all necessary adjustments, models can give the description of the canopy with fewer field measurements. In this paper model on leaf level was chosen. PROSPECT uses only five input variables: chlorophyll and carotenoid content, water content, dry matter and leaf structure parameter. Model is normally used to homogeneous canopy, like corn. In this paper, PROSPECT was used to simulate spectrum for heterogenic meadows using field measurements. Biophysical variables were collected during field measurements in the Bystrzanka catchment in the Low Beskid Mountains. In the same time more than 10 samples of spectrum were collected using ASD FieldSpec 3 FR and then averaged. The minimum size of polygon was 100m2. All input parameters for every polygon were included into the model and spectrum was modelled. Then spectrum was compared with measured samples of each polygon. In the end the vegetation indices were calculated using two kinds of spectrum and compared. All used vegetation indices are describing plant condition or crop monitoring: Normalized Difference Vegetation Index, Red Edge Normalized Difference Vegetation Index, Photochemical Reflectance Index, Normalized Difference Nitrogen Index, Normalized Difference Lignin Index, Cellulose Absorption Index, Carotenoid Reflectance Index, Water Band Index and Moisture Stress Index. Researches shows, that it is possible to simulate spectra for heterogeneous meadows using PROSPECT. The average RMSE value for all polygons was 0,0346, which mean the spectra are well modelled. The biggest mistake was for near infrared range, where is the strongest influence of dry matter content. The differences between measured and modelled spectrum were also noticed on the part of visible light – 400-500nm. For most calculated vegetation indices values were similar for both kinds of spectra. Values of NDVI,WBI and NDLI were very close. The biggest differences were noticed form PRI and CRI.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Accretion-disc model spectra for dwarf-nova stars
Autorzy:: Lasota, Jean-Pierre
Idan, I.
Hameury, J.-M.
Shaviv, G.
Dostawca treści:: Repozytorium Uniwersytetu Jagiellońskiego

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Skocz do pozycji: 5.

Tytuł:: Spectral and polarization properties of photospheric emission from stratified jets
Autorzy:: Ito, Hirotaka
Mao, Jirong
Tolstov, Alexey
Nagataki, Shigehiro
Lee, Shiu-Hang
Dainotti, Maria
Mizuta, Akira
Matsumoto, Jin
Dostawca treści:: Repozytorium Uniwersytetu Jagiellońskiego

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Skocz do pozycji: 6.

Tytuł:: Ocena skuteczności modeli transferu promieniowania w badaniach stanu roślinności łąk
Evaluation of radiative transfer models to simulate meadows reflectance
Autorzy:: Jarocińska, A.
Tematy:: łąka
krzywe
odbicie spektralne
Radiative Transfer Model
PROSPECT
SAIL
meadows
spectral reflectance; Pokaż więcej
Wydawca:: Polskie Towarzystwo Geograficzne
Powiązania:: https://bibliotekanauki.pl/articles/132309.pdf Link otwiera się w nowym oknie
Opis:: Vegetation analysis is an important problem in regional and global scale. Because of pollution of environment and changes in the ecosystems plant monitoring is very important. Remote sensing data can be easily used to plant monitoring. That kind of method is much faster and more reliable than traditional approaches. Spectrometry analyzes the interactions between radiation and object and it uses measurement of radiation intensity as a function of wavelength. Each object emits and absorbs different quantity of radiation, so it is possible to recognise the object and check its characteristics analysing the spectrum. The subject of the researches is Polish meadows. The human usage of the meadows determines its proper functioning. Grasslands, which consist of meadows and pastures, cover 10% of Poland. Meadows are most extensively use. In Poland the crops from meadows (hay and green forage) are very low. The meadows in Poland are floristically and morphologically very diverse. Many factors influence on this ecosystem and that is why the monitoring is very important. The aim of the researches is to study the possibility of use of the Radiative Transfer Models in modelling the state of the heterogeneous vegetation cover of seminatural meadows in Poland. Two approaches are used to canopy analysis: statistical and modelling. In the statistic approach, biophysical parameters calculated from the image are correlated with reflectance or transmittance from fi eld measurements. In second approach physically based model is used to represent the photon transport inside leaves and canopy. The Radiative Transfer Models are based on the laws of optics. Developing the model results in better understanding of the interaction of light in canopy and leaves. The Radiative Transfer Models are often applied to vegetation modelling. The Radiative Transfer Models are physically based models which describe the interactions of radiation in atmosphere and vegetation. Adjusted models can be used to fast and precise analysis of biophysical parameters of the canopy. The canopy can be described as homogeneous layer consisting of leaves and spaces. The Radiative Transfer Models are algorithms which vary by input and output parameters, the level of the analysis, kinds of plants and other modifications. Models are used on two levels: single leaf and whole canopy. The first model, which is used in this research, is PROSPECT, which describes the multidirectional refl ectance and diffusion on a leaf level. It is often employed with other models that describe whole canopy. Leaf has the same properties on both sides, the reflection from the leaves is Lambertian. The input parameters in the model are: chlorophyll and carotenoid content, Equivalent Water Thickness and dry matter content and also leaf structure parameter that describe the leaf structure and complexity. Second model, which is used in the study, is the canopy reflectance model SAIL (Scattering by Arbitrarily Inclined Leaves). It simulates the top of the canopy bidirectional reflectance and it describes the canopy structure in a fairly simple way. In this analysis the 4-SAIL model will be used. This version has few input parameters that describe plants and soil: spectrometric data – reflectance and transmittance from leaves (the output parameters form PROSPECT model), biophysical canopy parameters (Leaf Area Index, brown pigment content, mean leaf inclination angle), soil brightness parameter, reflectance geometry (solar zenith angle, observer zenith angle, relative azimuth angle), ratio of diffuse to total incident radiation and two hot spot size parameters. The SAIL model is often combined with the model on leaf level – the PROSAIL model. The PROSPECT and SAIL are very rarely used to meadows, this kind of ecosystem is normally rather heterogeneous and modelling is quite difficult. In this study two Radiative Transfer Models (PROSPECT-5 and 4SAIL) were used on single leaves and a whole canopy level. In order to acquire the input data to both, models model and reference spectrums the fi eld measurements were done. The input parameters were recalculated using fields measurements and put into the models: PROSPECT and PROSAIL. Only one leaf structure parameter was fitted for each polygon individually. The spectral reflectance obtained from the model was compared with field data. Based on the calculated Root Mean Square Error the simulation was verified. The RMSE values were calculated for whole range from 400 to 2500 nm and for specific ranges. The correctness of simulated spectra were analysed dependent on the type of meadows (cultivated meadows with reduced amount of biomass, cultivated meadows with high amount of biomass and not cultivated meadows) and the value of three different biophysical parameters (Leaf Area Index, fresh biomass content and water content). Better results were obtained using PROSPECT model than PROSAIL. In the visible light more accurate values were calculated using PROSAIL and in the infrared using PROSPECT. Generally bigger errors were noticed in the infrared, especially middle infrared range. The effectiveness of the reflectance simulation was not influenced by different kind of meadows. Apart from that, better results were obtained on meadows with higher biomass value, bigger Leaf Area Index and lower water content. Generally, the PROSPECT and PROSAIL radiative transfer models can be used to simulate the spectral reflectance of vegetation on heterogeneous meadows. The models can be used to estimate the biophysical parameters, but it is necessary to correct the values of input variables (especially water content). Meadows are very complex environment and some of the parameters should be adjusted.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Modelling of seawater polluted by light and heavy crude oil droplets
Autorzy:: Rudź, K.
Darecki, M.
Toczek, H.
Tematy:: oil pollution
remote sensing reflectance
Monte Carlo simulation
radiative transfer
oil-in-water emulsion; Pokaż więcej
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Powiązania:: https://bibliotekanauki.pl/articles/246668.pdf Link otwiera się w nowym oknie
Opis:: Significant amounts of crude oil transported from offshore fields to the refineries using tankers or pipelines, demand increased control of seawater pollution. Tanker accidents resulting in oil spills drive much attention, as they influence local marine life and coastal industry. However, the most significant annual amount of crude oil enters the sea in the form of oilin- water emulsion as a result of standard tanker operations, offshore oil extraction and daily work of refineries. Many branches of science are challenged to provide new methods for oil detection, less expensive, more sensitive and more accurate. Remote satellite or airborne detection of large oil spills is possible using joint techniques as microwave radars, ultraviolet laser fluorosensors and infrared radars. Some methods are capable to deal with oil streaks detection and estimation of oil thickness. Although there is currently, no method to detect small concentration of oil droplets dispersed in seawater. Oil droplets become additional absorbents and attenuators in water body. They significantly change seawater inherent optical properties, which imply the change of apparent optical properties, detectable using remote sensing techniques. To enable remote optical detection of oil-in-water emulsion, a study of optical properties of two types of crude oil was conducted. Radiative transfer theory was applied to quantify the contribution of oil emulsion to remote sensing reflectance (Rrs). Spectra of Rrs from in situ measurements in Baltic Sea were compared to Rrs spectra of seawater polluted by 1 ppm of crude oil emulsion, collected using radiative transfer simulation. The light crude oil caused a 9-10% increase of Rrs while the heavy one reduced Rrs up to 30% (model accuracy stayed within 5% for considered spectral range). Results are discussed concerning their application to shipboard and offshore oil content detection.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Emulsified fuels of machine origin in seawater - a contribute to remote detection
Autorzy:: Rudz, K.
Tematy:: oil pollution
remote sensing reflectance
Monte Carlo simulation
radiative transfer
oil-in-water emulsion; Pokaż więcej
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Powiązania:: https://bibliotekanauki.pl/articles/246040.pdf Link otwiera się w nowym oknie
Opis:: Development of industry and trade in the last few decades caused a huge increase in the pollution of the world's oceans. Substantial contributors to marine pollution come with the rivers from land-based sources including the by products of industry, run-off from agriculture activities such as biocides as well as effluents from urban areas. Moreover, a significant amount of marine pollution is caused by shipping and maritime activities. The operation of ship plants gives a real possibility for engine oils and fuels to reach the marine environment. Discharge waters contain a certain amount of petroleum derivatives in the form of dispersed droplets (oil-in-water emulsion). The presence of oil emulsion cause measurable changes in the optical properties of seawater. It is conceptually possible to detect these changes using a standard radiance or irradiance reflectance meter. Hence, a set of radiative transfer simulation has been carried out. This paper presents a computed photon trace simulation based on the Monte Carlo code, applied to the marine environment. The results are presented as reflectance spectra for the models of Baltic Sea and ocean water both pure and polluted by oil emulsion. It is shown that even small amounts of petroleum pollution raise the values of irradiance reflectance and cause a spectral shift by certain conditions. A possibility for remote evaluation of oil pollution is discussed as well as the perspective for improving the interpretation of shipboard and offshore light field analyses.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Emulsified fuels of machine origin in seawater - a contribute to remote detection
Autorzy:: Rudz, K.
Tematy:: oil pollution
remote sensing reflectance
Monte Carlo simulation
radiative transfer
oil-in-water emulsion; Pokaż więcej
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Powiązania:: https://bibliotekanauki.pl/articles/242232.pdf Link otwiera się w nowym oknie
Opis:: Development of industry and trade in the last few decades caused a huge increase in the pollution of the world's oceans. Substantial contributors to marine pollution come with the rivers from land-based sources including the by-products of industry, run-off from agriculture activities such as biocides as well as effluents from urban areas. Moreover, a significant amount of marine pollution is caused by shipping and maritime activities. The operation of ship plants gives a real possibility for engine oils and fuels to reach the marine environment. Discharge waters contain a certain amount of petroleum derivatives in the form of dispersed droplets (oil-in-water emulsion). The presence of oil emulsion cause measurable changes in the optical properties of seawater. It is conceptually possible to detect these changes using a standard radiance or irradiance reflectance meter. Hence, a set of radiative transfer simulation has been carried out. This paper presents a computed photon trace simulation based on the Monte Carlo code, applied to the marine environment. The results are presented as reflectance spectra for the models of Baltic Sea and ocean water both pure and polluted by oil emulsion. It is shown that even small amounts of petroleum pollution rise the values of irradiance reflectance and cause a spectral shift by certain conditions. A possibility for remote evaluation of oil pollution is discussed as well as the perspective for improving the interpretation of shipboard and offshore light field analyses.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: The temperature - and stress fields of valves of IC engine
Autorzy:: Jaskólski, J.
Krzyżak, R.
Tematy:: intake valve
output valve
YSZ
ferberite
scheelite
silicides
pyroxene
composite
joining of materials
thermal conductivity
radiative transfer
thermal expansion; Pokaż więcej
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Powiązania:: https://bibliotekanauki.pl/articles/243403.pdf Link otwiera się w nowym oknie
Opis:: The paper concerns building up one exhaust valve of composite-steel and two intake ceramics-steel valves of a hypothetical adiabatic engine. The input temperatures were computed using three diverse FORTRAN95 programs, solving a shortened optical integral equation with radiative transfer, transient differential equation while starting and switching off the engine and a rod like diff. Equation with 'progonka' (Thomas) solution. The ANSYS11 programme was fed up with the output of the programs. It turns out that, generally, a mineralogical, crystal-chemical approach to the joining of materials results in stresses known from the common metal engines. Such problems as CTE enhancing (partly hypothetical) by means of doping the anionic compounds by cationic ones, swelling of structures, compressibility versus coefficient of thermal expansion (CTE) , compatibility of crystal motifs while joining, thermal shock resistance, switching the bonds, mechanical longevity, radiation protection etc were addressed. It turns out that true nature of the temperature and stress field, especially of the exhaust valve is closer to the FORTRAN temperature computation than, e.g. From the heat film coefficients (ANSYS11).
Dostawca treści:: Biblioteka Nauki

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