Three-step three colour resonance ionization spectroscopy is employed in a linear time of flight mass spectrometer to investigate the autoionization spectra of atomic lutetium in the energy range 47360 - 53200 cm-1 above ground level. Using two-step excitation, Lu I atoms in ground / first meta-stable level are transferred to highly excited intermediate levels at ∼ 4 eV above the ground level and third laser is scanned to explore autoionization resonances connecting from the intermediate level. Total 71 odd-parity autoionization levels including 21 new levels are observed.
{"title":"New odd parity autoionization levels of Lu I by three-step three colour RIMS","authors":"Diptimayee Biswal , Laxmi priya Meher , Vipul Kumar , D.R. Rathod , Asawari D. Rath , Sanjay Sethi","doi":"10.1016/j.jqsrt.2025.109749","DOIUrl":"10.1016/j.jqsrt.2025.109749","url":null,"abstract":"<div><div>Three-step three colour resonance ionization spectroscopy is employed in a linear time of flight mass spectrometer to investigate the autoionization spectra of atomic lutetium in the energy range 47360 - 53200 cm<sup>-</sup><sup>1</sup> above ground level. Using two-step excitation, Lu I atoms in ground / first meta-stable level are transferred to highly excited intermediate levels at ∼ 4 eV above the ground level and third laser is scanned to explore autoionization resonances connecting from the intermediate level. Total 71 odd-parity autoionization levels including 21 new levels are observed.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"350 ","pages":"Article 109749"},"PeriodicalIF":1.9,"publicationDate":"2025-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145531873","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-12DOI: 10.1016/j.jqsrt.2025.109741
Steven Lanier
Simulating light interaction with complex arbitrary geometry is crucial across the sciences. The Discrete Dipole Approximation (DDA) offers versatility for such problems but faces significant computational challenges, particularly for optically large or high-index systems, limiting its practical scope. Prior circulant preconditioning work, building on frameworks by Chan and Olkin and applied to DDA by Groth et al., demonstrated speedups primarily for quasi-2D geometries while attempts to create stable three-level preconditioners for general 3D structures were unsuccessful. Here we present an efficient and robust DDA implementation featuring a successful three-level circulant preconditioner stabilized through several key enhancements: optimized complex diagonal elements, controlled dimensional expansion and folding of the preconditioner structure, and automated parameter tuning via reinforcement learning. This preconditioning strategy is integrated with a custom GPU iterative solver incorporating stability improvements. Our approach effectively handles arbitrary 3D geometries, including non-homogeneous objects with varying refractive indices and multi-object scenarios with differing material values. The implementation yields substantial computational gains, often exceeding an order of magnitude reduction in iteration count or solution time, enabling convergence for more traditionally difficult problems and reducing demanding simulations from hours to minutes or even seconds on standard hardware. This work significantly extends the range of complex systems amenable to DDA modeling, facilitating advanced electromagnetic simulations relevant to nanophotonics, materials characterization, and atmospheric/biological optics.
{"title":"Learning to precondition: Reinforcement learning enhanced three-level circulant preconditioning for the Discrete Dipole Approximation","authors":"Steven Lanier","doi":"10.1016/j.jqsrt.2025.109741","DOIUrl":"10.1016/j.jqsrt.2025.109741","url":null,"abstract":"<div><div>Simulating light interaction with complex arbitrary geometry is crucial across the sciences. The Discrete Dipole Approximation (DDA) offers versatility for such problems but faces significant computational challenges, particularly for optically large or high-index systems, limiting its practical scope. Prior circulant preconditioning work, building on frameworks by Chan and Olkin and applied to DDA by Groth et al., demonstrated speedups primarily for quasi-2D geometries while attempts to create stable three-level preconditioners for general 3D structures were unsuccessful. Here we present an efficient and robust DDA implementation featuring a successful three-level circulant preconditioner stabilized through several key enhancements: optimized complex diagonal elements, controlled dimensional expansion and folding of the preconditioner structure, and automated parameter tuning via reinforcement learning. This preconditioning strategy is integrated with a custom GPU iterative solver incorporating stability improvements. Our approach effectively handles arbitrary 3D geometries, including non-homogeneous objects with varying refractive indices and multi-object scenarios with differing material values. The implementation yields substantial computational gains, often exceeding an order of magnitude reduction in iteration count or solution time, enabling convergence for more traditionally difficult problems and reducing demanding simulations from hours to minutes or even seconds on standard hardware. This work significantly extends the range of complex systems amenable to DDA modeling, facilitating advanced electromagnetic simulations relevant to nanophotonics, materials characterization, and atmospheric/biological optics.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"350 ","pages":"Article 109741"},"PeriodicalIF":1.9,"publicationDate":"2025-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145515579","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-12DOI: 10.1016/j.jqsrt.2025.109738
Zhiguo Xu, Fuquan Zhang
Inspired by the spiny structure in the nature, this study applies the anti-reflection properties of cicada wing structures to near-field radiative heat transfer. The surface microstructure of different cicada wings is observed by SEM, their reflectivity is measured and a model for spiny particles is simplified and established. Thermal discrete dipole approximations method and magneto-optical materials InSb under a magnetic field is used to investigate spiny particles. The nonreciprocal near-field radiative heat transfer between four spiny particles is considered. Effects of spine radius, magnetic field and spine gap are studied. The interaction between scattering of different peaks in spiny particles leads to the valleys and peaks in relative conductance. As the magnetic field increases, the redshift and blueshift of the split peaks reduce the surface polaritons scattering interaction between the resonance main peak and the split peaks. The net clockwise conductance and overall persistent heat transfer ratio increases when the spine radius increases. The overall persistent heat transfer ratio of particles decreases when the gap increases.
{"title":"Reciprocal and nonreciprocal near-field radiative heat transfer between bio-inspired spiny particles under a magnetic field","authors":"Zhiguo Xu, Fuquan Zhang","doi":"10.1016/j.jqsrt.2025.109738","DOIUrl":"10.1016/j.jqsrt.2025.109738","url":null,"abstract":"<div><div>Inspired by the spiny structure in the nature, this study applies the anti-reflection properties of cicada wing structures to near-field radiative heat transfer. The surface microstructure of different cicada wings is observed by SEM, their reflectivity is measured and a model for spiny particles is simplified and established. Thermal discrete dipole approximations method and magneto-optical materials InSb under a magnetic field is used to investigate spiny particles. The nonreciprocal near-field radiative heat transfer between four spiny particles is considered. Effects of spine radius, magnetic field and spine gap are studied. The interaction between scattering of different peaks in spiny particles leads to the valleys and peaks in relative conductance. As the magnetic field increases, the redshift and blueshift of the split peaks reduce the surface polaritons scattering interaction between the resonance main peak and the split peaks. The net clockwise conductance and overall persistent heat transfer ratio increases when the spine radius increases. The overall persistent heat transfer ratio of particles decreases when the gap increases.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"350 ","pages":"Article 109738"},"PeriodicalIF":1.9,"publicationDate":"2025-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145515783","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-11DOI: 10.1016/j.jqsrt.2025.109740
Gennadiy Burlak , Gustavo Medina-Ángel
The semiclassical dynamics of optical nanoemitters (NEs) arranged in the shape of a Bernoulli lemniscate (LB), enhanced by plasmon–polaritons (PPs) in a lattice of conducting nanorings (NRs), are investigated. The coupling of PP and NE is mediated by a common optical field and NE with a finite lifetime of pumping are considered. Using the FDTD approach, it is found that the field structure and the NE dynamics significantly depend on the plasma frequency of the NR. If the intersection point of the LB branches (the region of high NE density) is located inside the NR gaps, a significant increase in the laser field strength and quantum cross-correlations in the NE subsystem occurs. This effect may be exploited to create new types of emitting devices using dispersed nano-objects in modern nanoelectronics.
{"title":"Semiclassical dynamics of the lemniscate ordered emitters enhanced by plasmon-polaritons in nanorings","authors":"Gennadiy Burlak , Gustavo Medina-Ángel","doi":"10.1016/j.jqsrt.2025.109740","DOIUrl":"10.1016/j.jqsrt.2025.109740","url":null,"abstract":"<div><div>The semiclassical dynamics of optical nanoemitters (NEs) arranged in the shape of a Bernoulli lemniscate (LB), enhanced by plasmon–polaritons (PPs) in a lattice of conducting nanorings (NRs), are investigated. The coupling of PP and NE is mediated by a common optical field and NE with a finite lifetime of pumping are considered. Using the FDTD approach, it is found that the field structure and the NE dynamics significantly depend on the plasma frequency of the NR. If the intersection point of the LB branches (the region of high NE density) is located inside the NR gaps, a significant increase in the laser field strength and quantum cross-correlations in the NE subsystem occurs. This effect may be exploited to create new types of emitting devices using dispersed nano-objects in modern nanoelectronics.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"350 ","pages":"Article 109740"},"PeriodicalIF":1.9,"publicationDate":"2025-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145498984","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-11DOI: 10.1016/j.jqsrt.2025.109739
Renxian Li , Yuexiao Jiao , Li Xiao , Huan Tang , Bing Wei , Shuhong Gong , Denis Novitsky , Igor V. Minin , Oleg V. Minin
Optical forces proved to be extremely useful for manipulating and trapping nano- and microparticles. Such applications are especially needed for microfluidic systems to reliably control streams of nanoparticles. In this paper, we propose to optically trap nanoparticles using an inclined photonic jet modulated by a standing wave and generated with a cut cylinder partially blocked from the incident plane waves by a variable metal screen. Our theoretical analysis is based on the Finite Difference Frequency Domain (FDFD) method for the electric field and the optical energy flux calculations and on the Rayleigh model for the optical force calculation. The effects of the cut-cylinder central angle and shape of the metal screen on the standing wave formation and the optical force distribution are numerically demonstrated. We show that the quality of the optical trap can be increased by adjusting the parameters of the model cut-cylinder central angle and estimating the stability of the resulting trap. The cut cylinder can be used as an ingenious microfluidic channel that has potential applications for the optical trapping of nanoparticles and the development of optical tweezers.
{"title":"Standing photonic jets for stable nanoparticle trapping in cut-cylinder microfluidic channels","authors":"Renxian Li , Yuexiao Jiao , Li Xiao , Huan Tang , Bing Wei , Shuhong Gong , Denis Novitsky , Igor V. Minin , Oleg V. Minin","doi":"10.1016/j.jqsrt.2025.109739","DOIUrl":"10.1016/j.jqsrt.2025.109739","url":null,"abstract":"<div><div>Optical forces proved to be extremely useful for manipulating and trapping nano- and microparticles. Such applications are especially needed for microfluidic systems to reliably control streams of nanoparticles. In this paper, we propose to optically trap nanoparticles using an inclined photonic jet modulated by a standing wave and generated with a cut cylinder partially blocked from the incident plane waves by a variable metal screen. Our theoretical analysis is based on the Finite Difference Frequency Domain (FDFD) method for the electric field and the optical energy flux calculations and on the Rayleigh model for the optical force calculation. The effects of the cut-cylinder central angle and shape of the metal screen on the standing wave formation and the optical force distribution are numerically demonstrated. We show that the quality of the optical trap can be increased by adjusting the parameters of the model cut-cylinder central angle and estimating the stability of the resulting trap. The cut cylinder can be used as an ingenious microfluidic channel that has potential applications for the optical trapping of nanoparticles and the development of optical tweezers.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"350 ","pages":"Article 109739"},"PeriodicalIF":1.9,"publicationDate":"2025-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145498979","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-07DOI: 10.1016/j.jqsrt.2025.109736
T. Bertin , I.E. Gordon , R.J. Hargreaves , J. Tennyson , S.N. Yurchenko , K. Kefala , V. Boudon , C. Richard , A.V. Nikitin , V.G. Tyuterev , M. Rey , M. Birk , G. Wagner , K. Sung , B.P. Coy , W. Broussard , G.C. Toon , A.A. Rodina , E. Starikova , A. Campargue , G.B. Rieker
Spectroscopic parameters of methane from many different studies were gathered to improve the HITRAN database towards its 2024 version. After a validation process using high-resolution FTS and CRDS spectra, about 80,000 lines of the four most abundant isotopologues were replaced from the dyad to the triacontad regions. These changes amount to 51,000 transition wavenumbers, 18,000 line intensities, 33,000 pressure-broadening half-widths, and 3300 assignments. 44,000 new lines were added with 16,000 old lines removed, extending the database from 12,000 cm−1 up to 14,000 cm−1, and covering some gaps. A greater focus was brought on the pentad, octad, and tetradecad regions, targeted by several remote sensing instruments. In these regions, comparisons of spectral fits from multiple line lists were performed, taking only the parameters that provide best fit for each line. In the band, in addition to replacing the previous values, speed-independent pressure broadening parameters of 12CH4 were gathered and used to fit Padé-approximant functions. These functions then replaced any outdated experimental data in , missing data in the new lines, as well as the values that were determined to be outside their physical boundaries. The CH3D broadening parameters were replaced in the same manner, for missing and low or high values, using a semi-empirical formula instead.
{"title":"The HITRAN2024 methane update","authors":"T. Bertin , I.E. Gordon , R.J. Hargreaves , J. Tennyson , S.N. Yurchenko , K. Kefala , V. Boudon , C. Richard , A.V. Nikitin , V.G. Tyuterev , M. Rey , M. Birk , G. Wagner , K. Sung , B.P. Coy , W. Broussard , G.C. Toon , A.A. Rodina , E. Starikova , A. Campargue , G.B. Rieker","doi":"10.1016/j.jqsrt.2025.109736","DOIUrl":"10.1016/j.jqsrt.2025.109736","url":null,"abstract":"<div><div>Spectroscopic parameters of methane from many different studies were gathered to improve the HITRAN database towards its 2024 version. After a validation process using high-resolution FTS and CRDS spectra, about 80,000 lines of the four most abundant isotopologues were replaced from the dyad to the triacontad regions. These changes amount to 51,000 transition wavenumbers, 18,000 line intensities, 33,000 pressure-broadening half-widths, and 3300 assignments. 44,000 new lines were added with 16,000 old lines removed, extending the database from 12,000 cm<sup>−1</sup> up to 14,000 cm<sup>−1</sup>, and covering some gaps. A greater focus was brought on the pentad, octad, and tetradecad regions, targeted by several remote sensing instruments. In these regions, comparisons of spectral fits from multiple line lists were performed, taking only the parameters that provide best fit for each line. In the <span><math><msub><mrow><mi>ν</mi></mrow><mrow><mn>3</mn></mrow></msub></math></span> band, in addition to replacing the previous values, speed-independent pressure broadening parameters of <sup>12</sup>CH<sub>4</sub> were gathered and used to fit Padé-approximant functions. These functions then replaced any outdated experimental data in <span><math><msub><mrow><mi>ν</mi></mrow><mrow><mn>3</mn></mrow></msub></math></span>, missing data in the new lines, as well as the values that were determined to be outside their physical boundaries. The CH<sub>3</sub>D broadening parameters were replaced in the same manner, for missing and low or high values, using a semi-empirical formula instead.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"349 ","pages":"Article 109736"},"PeriodicalIF":1.9,"publicationDate":"2025-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145461886","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-05DOI: 10.1016/j.jqsrt.2025.109732
Jie Luo , Yangyang Ma , Miao Hu , Congcong Li , Hongjin Li , Xiulin Geng , Meihua Bi , Xuefang Zhou
The morphology of certain atmospheric particles, such as dust, is highly complex, yet remote sensing retrieval methods often employ simplified morphological representations. extensive research has demonstrated that particle morphology significantly influences optical properties, it remains uncertain whether a set of simple models can represent the optical properties of more complex particles. Based on scattering matrices of irregularly shaped model particle ensembles, we assume a lognormal distribution of aspect ratios and invert for the optimal spheroidal particle ensemble to evaluate its ability to replicate the optical and polarimetric properties of particles with more intricate and irregular morphologies. This work compares the performance of both the best-fit single spheroid and the best-fit spheroidal ensemble in simulating the scattering matrix of irregular particles. Our findings indicate that the suitability of the spheroidal-based simulation of the scattering matrix is significantly affected by different shapes. Additionally, the applicability of the spheroidal ensemble is investigated in the context of simulating satellite polarimetric observations, using a vector radiative transfer model with irregular particles as the reference. Results reveal that the normalized radiance simulated by the optimal spheroidal ensemble can deviate by approximately 6% from that of irregular particles, while differences in the polarized bidirectional reflectance factor (pBRF) and the degree of linear polarization (DoLP) range from –0.0015 to 0.0015 and –0.03 to 0.06, respectively. Moreover, the distribution of the best-fit aspect ratios for irregular particles of varying shapes is analyzed. This study provides valuable insights for employing simplified models to assess uncertainty sources in remote sensing applications.
{"title":"Suitability of a group of spheroids with a lognormal shape distribution for modeling the scattering and polarimetric properties of irregular particles","authors":"Jie Luo , Yangyang Ma , Miao Hu , Congcong Li , Hongjin Li , Xiulin Geng , Meihua Bi , Xuefang Zhou","doi":"10.1016/j.jqsrt.2025.109732","DOIUrl":"10.1016/j.jqsrt.2025.109732","url":null,"abstract":"<div><div>The morphology of certain atmospheric particles, such as dust, is highly complex, yet remote sensing retrieval methods often employ simplified morphological representations. extensive research has demonstrated that particle morphology significantly influences optical properties, it remains uncertain whether a set of simple models can represent the optical properties of more complex particles. Based on scattering matrices of irregularly shaped model particle ensembles, we assume a lognormal distribution of aspect ratios and invert for the optimal spheroidal particle ensemble to evaluate its ability to replicate the optical and polarimetric properties of particles with more intricate and irregular morphologies. This work compares the performance of both the best-fit single spheroid and the best-fit spheroidal ensemble in simulating the scattering matrix of irregular particles. Our findings indicate that the suitability of the spheroidal-based simulation of the scattering matrix is significantly affected by different shapes. Additionally, the applicability of the spheroidal ensemble is investigated in the context of simulating satellite polarimetric observations, using a vector radiative transfer model with irregular particles as the reference. Results reveal that the normalized radiance simulated by the optimal spheroidal ensemble can deviate by approximately 6% from that of irregular particles, while differences in the polarized bidirectional reflectance factor (pBRF) and the degree of linear polarization (DoLP) range from –0.0015 to 0.0015 and –0.03 to 0.06, respectively. Moreover, the distribution of the best-fit aspect ratios for irregular particles of varying shapes is analyzed. This study provides valuable insights for employing simplified models to assess uncertainty sources in remote sensing applications.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"349 ","pages":"Article 109732"},"PeriodicalIF":1.9,"publicationDate":"2025-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145447635","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-05DOI: 10.1016/j.jqsrt.2025.109722
Zili He , Sandrine Vinatier , Vincent Eymet , Vincent Forest , Bruno Bézard , Pascal Rannou , Sébastien Rodriguez , Emmanuel Marcq , Richard Fournier , Stéphane Blanco , Nada Mourtaday , Yaniss Nyffenegger-Péré , Sébastien Lebonnois , Anni Määttänen
The study of planetary atmospheres and surfaces depends on integrating radiative transfer modelling with inversion techniques. Traditional radiative transfer models, which assume simplified geometries (e.g., parallel-plan approximation), are limited in accurately capturing the heterogeneous and spherical nature of planetary atmospheres and surfaces, especially in spectral ranges where the scattering effects are important. Numerous modelling strategies are available with full accuracy in the representation of 3D features, but coupling such realistic radiative transfer model with inversion techniques raises challenges in calculation time and gradient assessment. Thanks to the recent active research at the interface between statistical physics and computer graphics, we here tackle these challenges based on the propositions of null-collision (Galtier et al., 2013) and spatial partitioning of extinction-coefficients overestimates (Villefranque et al., 2019). Straightforwardly, these propositions are implemented here for planetary atmospheres and we also provide a slightly modified version of the algorithm that simultaneously estimates the radiance and its gradient with respect to the radiative properties (e.g., absorption coefficients, scattering coefficients and surface reflectivities). Gradient estimation preserves the insensitivity of calculation time to the geometric complexity. The method is applied to Titan. Its performance and limitations are discussed together with the perspectives of being integrated into the inversion routine of planetary data.
{"title":"Simultaneous estimation of radiance and its sensitivities to radiative properties in a spherical-heterogeneous atmospheric radiative transfer model by Monte Carlo method: Application to Titan","authors":"Zili He , Sandrine Vinatier , Vincent Eymet , Vincent Forest , Bruno Bézard , Pascal Rannou , Sébastien Rodriguez , Emmanuel Marcq , Richard Fournier , Stéphane Blanco , Nada Mourtaday , Yaniss Nyffenegger-Péré , Sébastien Lebonnois , Anni Määttänen","doi":"10.1016/j.jqsrt.2025.109722","DOIUrl":"10.1016/j.jqsrt.2025.109722","url":null,"abstract":"<div><div>The study of planetary atmospheres and surfaces depends on integrating radiative transfer modelling with inversion techniques. Traditional radiative transfer models, which assume simplified geometries (e.g., parallel-plan approximation), are limited in accurately capturing the heterogeneous and spherical nature of planetary atmospheres and surfaces, especially in spectral ranges where the scattering effects are important. Numerous modelling strategies are available with full accuracy in the representation of 3D features, but coupling such realistic radiative transfer model with inversion techniques raises challenges in calculation time and gradient assessment. Thanks to the recent active research at the interface between statistical physics and computer graphics, we here tackle these challenges based on the propositions of null-collision (Galtier et al., 2013) and spatial partitioning of extinction-coefficients overestimates (Villefranque et al., 2019). Straightforwardly, these propositions are implemented here for planetary atmospheres and we also provide a slightly modified version of the algorithm that simultaneously estimates the radiance and its gradient with respect to the radiative properties (e.g., absorption coefficients, scattering coefficients and surface reflectivities). Gradient estimation preserves the insensitivity of calculation time to the geometric complexity. The method is applied to Titan. Its performance and limitations are discussed together with the perspectives of being integrated into the inversion routine of planetary data.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"350 ","pages":"Article 109722"},"PeriodicalIF":1.9,"publicationDate":"2025-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145447993","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-04DOI: 10.1016/j.jqsrt.2025.109735
Yujia Sun , Chenxin Lin , Shu Zheng
Thermal radiation plays an important role in combustion systems due to its significant effect on the energy evolution. Radiation modeling in combustion simulations needs expensive computational resources due to high complexity of the radiative transfer equation and highly variations of the spectral radiative properties. Traditional numerical methods for the radiation modeling have many simplified and approximated models, but they are still suffering from the irreconcilable conflict between the accuracy and efficiency. This work investigates the capability of machine learning for predicting radiative heat transfer in combustion scenarios. Two machine learning models, UNet model and Fourier network operator (FNO) model are designed to learn radiative heat transfer directly from the temperature and concentrations fields. Their performances are tested for a turbulent diffusion flame. Results show that both UNet and FNO performs well for emulating the radiative heat source for the considered flame, with relative errors generally smaller than 0.3 %. The two models have similar accuracies. This study demonstrates the feasibility of using UNet and FNO models as surrogate model for non-gray gas radiative heat transfer in combustion system, but they need further investigations for more complex combustion scenarios.
{"title":"Emulating non-gray gas radiative heat transfer in combustion scenarios by machine learning method","authors":"Yujia Sun , Chenxin Lin , Shu Zheng","doi":"10.1016/j.jqsrt.2025.109735","DOIUrl":"10.1016/j.jqsrt.2025.109735","url":null,"abstract":"<div><div>Thermal radiation plays an important role in combustion systems due to its significant effect on the energy evolution. Radiation modeling in combustion simulations needs expensive computational resources due to high complexity of the radiative transfer equation and highly variations of the spectral radiative properties. Traditional numerical methods for the radiation modeling have many simplified and approximated models, but they are still suffering from the irreconcilable conflict between the accuracy and efficiency. This work investigates the capability of machine learning for predicting radiative heat transfer in combustion scenarios. Two machine learning models, UNet model and Fourier network operator (FNO) model are designed to learn radiative heat transfer directly from the temperature and concentrations fields. Their performances are tested for a turbulent diffusion flame. Results show that both UNet and FNO performs well for emulating the radiative heat source for the considered flame, with relative errors generally smaller than 0.3 %. The two models have similar accuracies. This study demonstrates the feasibility of using UNet and FNO models as surrogate model for non-gray gas radiative heat transfer in combustion system, but they need further investigations for more complex combustion scenarios.</div></div>","PeriodicalId":16935,"journal":{"name":"Journal of Quantitative Spectroscopy & Radiative Transfer","volume":"349 ","pages":"Article 109735"},"PeriodicalIF":1.9,"publicationDate":"2025-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145435107","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-01DOI: 10.1016/j.jqsrt.2025.109723
I. Majdi , S. Harbaoui , D. Ben Abdallah , J. Salem , Z. Boussetta , F. Kwabia Tchana , X. Landsheere , A. Voute , M. Hochlaf , H. Aroui
In the present work, we measured the O2-broadening coefficients of the absorption lines in the ν2 and ν5 bands of methyl bromide at room temperature (T = 295 K) using a high-resolution Fourier Transform spectrometer. Eight spectra were recorded at pressures ranging from 2.0 to 6.5 Torr for the active gas and from 3 to 90 Torr for the perturber gas. The line shape parameters were obtained by fitting Voigt and Galatry profiles to the measured line shapes, allowing the determination of the O2-broadening coefficients for the branches over the 1250 – 1622 cm-1 wavenumbers range. This range covers 1451 measured transitions with 2 ≤ J ≤ 54 and 0 ≤ K ≤ 10. These data, combined with previously measured N2-broadening coefficients, were used to determine the air-broadening coefficients of the ν2 and ν5 bands. Finally, an empirical model was used to fit the broadening coefficients of the two bands. On average, the empirical expression reproduces successfully the measured broadening coefficients.
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