Pub Date : 2025-10-01DOI: 10.1016/j.rinp.2025.108459
Seong-Han Kim, Chul-Sik Kee
We present a numerical demonstration that a periodic structure composed of alternating perfect magnetic conductor (PMC) and perfect electric conductor (PEC) parallel-plate waveguides (PPWs), filled with dielectric materials of permittivity and , and separated by a gap , exhibits hyperbolic dispersion and negative refraction. This phenomenon is enabled by surface waves confined at the PMC–PEC interfaces and disappears when the dielectric permittivities are equal (), eliminating surface wave support. Furthermore, the hyperbolic nature of the dispersion is confirmed by simulated radiation patterns from a point dipole source embedded in the periodic structure.
{"title":"Hyperbolic dispersion and negative refraction in a periodic perfect magnetic conductor and perfect electric conductor parallel-plate waveguide structure","authors":"Seong-Han Kim, Chul-Sik Kee","doi":"10.1016/j.rinp.2025.108459","DOIUrl":"10.1016/j.rinp.2025.108459","url":null,"abstract":"<div><div>We present a numerical demonstration that a periodic structure composed of alternating perfect magnetic conductor (PMC) and perfect electric conductor (PEC) parallel-plate waveguides (PPWs), filled with dielectric materials of permittivity <span><math><msub><mrow><mi>ɛ</mi></mrow><mrow><mn>1</mn></mrow></msub></math></span> and <span><math><msub><mrow><mi>ɛ</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>, and separated by a gap <span><math><mi>h</mi></math></span>, exhibits hyperbolic dispersion and negative refraction. This phenomenon is enabled by surface waves confined at the PMC–PEC interfaces and disappears when the dielectric permittivities are equal (<span><math><mrow><msub><mrow><mi>ɛ</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>=</mo><msub><mrow><mi>ɛ</mi></mrow><mrow><mn>2</mn></mrow></msub></mrow></math></span>), eliminating surface wave support. Furthermore, the hyperbolic nature of the dispersion is confirmed by simulated radiation patterns from a point dipole source embedded in the periodic structure.</div></div>","PeriodicalId":21042,"journal":{"name":"Results in Physics","volume":"77 ","pages":"Article 108459"},"PeriodicalIF":4.6,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145221756","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2025-10-01DOI: 10.1016/j.rinp.2025.108451
Talha Anwar , Kashif Ullah , Mehreen Fiza , Hakeem Ullah , Ibrahim Mahariq , Seham M. Al Mekhlafi
Significance
The outstanding thermal conductivity and heat transfer properties of nanofluid make them highly useful for applications in thermal engineering and other areas. With their improved effectiveness, nanofluid significantly enhance the performance of heating, cooling, and overall thermal regulation systems. Hybrid nanofluids are used in industry as heat-transport fluids in gas turbine rotators and rotating machinery. Recurrent neural network has garnered significant attention in academic research for their ability in modeling complex, nonlinear systems. Their adaptability makes them highly appropriate for advanced domains such as fluid dynamics, natural language processing, biological computing, control systems, multimedia and biotechnology, where pattern learning and recognition are critical.
Purpose
This study explores heat transport in ternary hybrid nanofluid comprising capper, silver, and alumina nanoparticles between two stretching spinning disks at a constant distance. It integrates the effects of thermal radiation, joule effect, heat source, and activation energy to assess their combined influence on flow and thermal characteristics. The work further investgates the capability of a recurrent neural networks enhanced with the Levenberg-Marquardt method (RNN-LMM) to accurately model and predict these complex thermos fluid phenamena.
Methodology
Through similarity transformation, the governing partial differential equations are reduced to dimensionless ordinary differntiao equations, which are then solved using the RNN-LMM. Data for the study, was obtained using the Adams numerical method and further optimized through the recurrent neural network’s framework. The model was trained on eighty percent of the dataset, with ten percent allocated for testing and ten percent for validation. Performance assessment was conducted using mean squared error (MSE), regression analysis, and histogram-based error distribution, with accuracy in the range of E−3 to E−7. Graphical analysis was employed to investigate the influence of key physical parameters on velocity, temperature, and concentration fields.
Finding: Results reveal that an increase in the magnetic parameter augments both velocity and temperature distributions. The Reynolds number significantly affects radial, tangential and axial velocity components, promoting overall fluid motion. Activation energy positive effect ternary hybrid nanofluid (THNF) concentration, whereas the Schmidt number and chemical reaction rate decrease it, highlighting their opposing effects. All examined factors contribute to elevated temperature profiles. The reduced MSE indicates that RNN-LMM predictions closely match true values, confirming the methods reliability and accuracy.
{"title":"Recurrent neural network approach to thermal radiation in hybrid nanofluids with activation energy between two rotating disks","authors":"Talha Anwar , Kashif Ullah , Mehreen Fiza , Hakeem Ullah , Ibrahim Mahariq , Seham M. Al Mekhlafi","doi":"10.1016/j.rinp.2025.108451","DOIUrl":"10.1016/j.rinp.2025.108451","url":null,"abstract":"<div><h3>Significance</h3><div>The outstanding thermal conductivity and heat transfer properties of nanofluid make them highly useful for applications in thermal engineering and other areas. With their improved effectiveness, nanofluid significantly enhance the performance of heating, cooling, and overall thermal regulation systems. Hybrid nanofluids are used in industry as heat-transport fluids in gas turbine rotators and rotating machinery. Recurrent neural network has garnered significant attention in academic research for their ability in modeling complex, nonlinear systems. Their adaptability makes them highly appropriate for advanced domains such as fluid dynamics, natural language processing, biological computing, control systems, multimedia and biotechnology, where pattern learning and recognition are critical.</div></div><div><h3>Purpose</h3><div>This study explores heat transport in ternary hybrid nanofluid comprising capper, silver, and alumina nanoparticles between two stretching spinning disks at a constant distance. It integrates the effects of thermal radiation, joule effect, heat source, and activation energy to assess their combined influence on flow and thermal characteristics. The work further investgates the capability of a recurrent neural networks enhanced with the Levenberg-Marquardt method (RNN-LMM) to accurately model and predict these complex thermos fluid phenamena.</div></div><div><h3>Methodology</h3><div>Through similarity transformation, the governing partial differential equations are reduced to dimensionless ordinary differntiao equations, which are then solved using the RNN-LMM. Data for the study, was obtained using the Adams numerical method and further optimized through the recurrent neural network’s framework. The model was trained on eighty percent of the dataset, with ten percent allocated for testing and ten percent for validation. Performance assessment was conducted using mean squared error (MSE), regression analysis, and histogram-based error distribution, with accuracy in the range of E−3 to E−7. Graphical analysis was employed to investigate the influence of key physical parameters on velocity, temperature, and concentration fields.</div><div>Finding: Results reveal that an increase in the magnetic parameter augments both velocity and temperature distributions. The Reynolds number significantly affects radial, tangential and axial velocity components, promoting overall fluid motion. Activation energy positive effect ternary hybrid nanofluid (THNF) concentration, whereas the Schmidt number and chemical reaction rate decrease it, highlighting their opposing effects. All examined factors contribute to elevated temperature profiles. The reduced MSE indicates that RNN-LMM predictions closely match true values, confirming the methods reliability and accuracy.</div></div>","PeriodicalId":21042,"journal":{"name":"Results in Physics","volume":"77 ","pages":"Article 108451"},"PeriodicalIF":4.6,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145268501","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2025-10-01DOI: 10.1016/j.rinp.2025.108466
Emre Deniz Yalçın
In this detailed study, the physical, mechanical, and tribological properties of AISI 4140 steel samples subjected to quench hardening with 10 wt% sodium hydroxide (NaOH) solution and then coated with Aluminium Titanium Chromium Nitride (AlTiCrN) using Physical Vapour Deposition (PVD) technique were investigated. The study included microstructure characterization, phase analysis, coating thickness linear measurements, microhardness, tribological analysis, and evaluation of worn surface examinations, aiming to distinguish the combined effect of AlTiCrN coating and hardening process. The surface properties, elemental distribution, and post-wear tribological properties of the coating layer were investigated in detail using X-ray Diffraction (XRD) and Energy Dispersive Spectroscopy (EDS) techniques assisted by Scanning Electron Microscopy (SEM). Tribological tests were carried out with a liner wear tribometer at three different wear distances of 500, 1000, and 1500 m under 30 N load. When the results were examined, the hardness obtained from the sample without any heat treatment was 480 HV, while the hardness of the sample hardened by heat treatment with NaOH solution was measured as 696 HV. The hardness of the sample hardened with NaOH solution and coated with AlTiCrN was measured as 1732 HV. It was observed that NaOH solution heat treatment caused a significant increase in the hardness values of the samples. As a result, NaOH solution heat treatment was observed to be a highly effective correlation in improving the physical, mechanical, and tribological properties of AlTiCrN coating and 4140 steel.
{"title":"Tribological performance of AISI 4140 steel quenching hardened with NaOH solution and coated with AlTiCrN by PVD method","authors":"Emre Deniz Yalçın","doi":"10.1016/j.rinp.2025.108466","DOIUrl":"10.1016/j.rinp.2025.108466","url":null,"abstract":"<div><div>In this detailed study, the physical, mechanical, and tribological properties of AISI 4140 steel samples subjected to quench hardening with 10 wt% sodium hydroxide (NaOH) solution and then coated with Aluminium Titanium Chromium Nitride (AlTiCrN) using Physical Vapour Deposition (PVD) technique were investigated. The study included microstructure characterization, phase analysis, coating thickness linear measurements, microhardness, tribological analysis, and evaluation of worn surface examinations, aiming to distinguish the combined effect of AlTiCrN coating and hardening process. The surface properties, elemental distribution, and post-wear tribological properties of the coating layer were investigated in detail using X-ray Diffraction (XRD) and Energy Dispersive Spectroscopy (EDS) techniques assisted by Scanning Electron Microscopy (SEM). Tribological tests were carried out with a liner wear tribometer at three different wear distances of 500, 1000, and 1500 m under 30 N load. When the results were examined, the hardness obtained from the sample without any heat treatment was 480 HV, while the hardness of the sample hardened by heat treatment with NaOH solution was measured as 696 HV. The hardness of the sample hardened with NaOH solution and coated with AlTiCrN was measured as 1732 HV. It was observed that NaOH solution heat treatment caused a significant increase in the hardness values of the samples. As a result, NaOH solution heat treatment was observed to be a highly effective correlation in improving the physical, mechanical, and tribological properties of AlTiCrN coating and 4140 steel.</div></div>","PeriodicalId":21042,"journal":{"name":"Results in Physics","volume":"77 ","pages":"Article 108466"},"PeriodicalIF":4.6,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145221753","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2025-10-01DOI: 10.1016/j.rinp.2025.108449
Sina Gouran , Mohamed Bechir Ben Hamida , Hijaz Ahmad , Saad Alshahrani
Considering the nanofluid working through two coaxial cylinders, the particular contribution of the present work is to evaluate the combined effects of the heat generation/absorption and exponential magnetic field on the overall thermal performance. After reintroducing the non-dimensional form of governing equations, the Differential Quadrature Method is used as a numerical procedure to acquire the flow field characteristics. A suitable agreement is found by comparing the present findings with those from previous work. At the same Reynolds number, heat transfer rate increases by 24 % using nanoparticles, while 21 percent enhancement is reported for the heat transfer rate in the presence of nanoparticles. Adding 0.1 percent nanoparticles to the base flow for the different heat generation/absorption parameters 1, 3, and 6, results in an improvement in the heat transfer rate to 21, 18, and 14 percent, respectively. Entropy generation is also a key factor in energy management in every thermal process. Therefore, entropy generation due to different heat generation/absorption and magnetic parameters is analyzed. Moreover, the role of heat transfer irreversibility on the overall energy losses is investigated.
{"title":"Entropy generation and heat transfer investigation of a nanofluid subject to an exponential magnetic field","authors":"Sina Gouran , Mohamed Bechir Ben Hamida , Hijaz Ahmad , Saad Alshahrani","doi":"10.1016/j.rinp.2025.108449","DOIUrl":"10.1016/j.rinp.2025.108449","url":null,"abstract":"<div><div>Considering the nanofluid working through two coaxial cylinders, the particular contribution of the present work is to evaluate the combined effects of the heat generation/absorption and exponential magnetic field on the overall thermal performance. After reintroducing the non-dimensional form of governing equations, the Differential Quadrature Method is used as a numerical procedure to acquire the flow field characteristics. A suitable agreement is found by comparing the present findings with those from previous work. At the same Reynolds number, heat transfer rate increases by 24 % using <span><math><mrow><mi>A</mi><mi>A</mi><mn>7072</mn></mrow></math></span> nanoparticles, while 21 percent enhancement is reported for the heat transfer rate in the presence of <span><math><mrow><msub><mrow><mi>Al</mi></mrow><mn>2</mn></msub><msub><mi>O</mi><mn>3</mn></msub></mrow></math></span> nanoparticles. Adding 0.1 percent nanoparticles to the base flow for the different heat generation/absorption parameters 1, 3, and 6, results in an improvement in the heat transfer rate to 21, 18, and 14 percent, respectively. Entropy generation is also a key factor in energy management in every thermal process. Therefore, entropy generation due to different heat generation/absorption and magnetic parameters is analyzed. Moreover, the role of heat transfer irreversibility on the overall energy losses is investigated.</div></div>","PeriodicalId":21042,"journal":{"name":"Results in Physics","volume":"77 ","pages":"Article 108449"},"PeriodicalIF":4.6,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145221621","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2025-10-01DOI: 10.1016/j.rinp.2025.108462
Mehrunisa Moin , Hairong Zhao , Muhammad Moin , Lizhuang Dong , Abdul Waheed Anwar , Udayabhaskararao Thumu
Chalcogenide perovskites of the form ABS3 have recently gained attention as a promising class of hybrid materials, owing to their excellent structural stability, environmentally benign composition, and intriguing optoelectronic characteristics. In this study, we present a systematic investigation of pristine and Sn-doped BaHf1-xSnxS3, BaZr1-xSnxS3, and CaHf1-xSnxS3 (with x = 0.0, 0.25, 0.50, and 0.75) materials, focusing on the tunability of their band gaps and associated physical properties. Using ab initio density functional theory (DFT), we explore their structural, electronic, mechanical, optical, and thermodynamic behavior. The incorporation of Sn doping significantly improves lattice coefficients and volumes, positively influencing structural responses. The calculated electronic band gaps decrease significantly with increasing Sn doping (up to x = 0.75), ranging from 1.99 eV in the pristine phases to as low as 0.78 eV, indicating enhanced electronic conductivity. Mechanical property analyses, including the Pugh ratio B/G), Poisson ratio (ν), and Cauchy pressure, reveal that BaHf1-xSnxS3 and BaZr1-xSnxS3 exhibit ductile characteristics, whereas CaHfS3 maintains mechanical stability with a brittle nature. Optical properties evaluated in the 0 to 40 eV energy range display high absorption coefficients, significant optical conductivity, and notable reflectivity, indicating promising optoelectronic performance. Thermodynamic analyses covering Debye temperature, specific heat capacity, entropy, enthalpy, Gibbs free energy, and phonon spectra highlight a transition from thermodynamic instability in pristine structures to enhanced stability upon Sn doping. Overall, the integration of structural tunability, improved electronic and optical performance, and enhanced thermodynamic stability in these chalcogenide perovskites underscores their strong potential for next-generation optoelectronic devices.
{"title":"First-principles investigation of Sn4+ doping effects on the optoelectronic properties of BaHfS3, BaZrS3, and CaHfS3 chalcogenide perovskites","authors":"Mehrunisa Moin , Hairong Zhao , Muhammad Moin , Lizhuang Dong , Abdul Waheed Anwar , Udayabhaskararao Thumu","doi":"10.1016/j.rinp.2025.108462","DOIUrl":"10.1016/j.rinp.2025.108462","url":null,"abstract":"<div><div>Chalcogenide perovskites of the form ABS<sub>3</sub> have recently gained attention as a promising class of hybrid materials, owing to their excellent structural stability, environmentally benign composition, and intriguing optoelectronic characteristics. In this study, we present a systematic investigation of pristine and Sn-doped BaHf<sub>1-x</sub>Sn<sub>x</sub>S<sub>3</sub>, BaZr<sub>1-x</sub>Sn<sub>x</sub>S<sub>3</sub>, and CaHf<sub>1-x</sub>Sn<sub>x</sub>S<sub>3</sub> (with x = 0.0, 0.25, 0.50, and 0.75) materials, focusing on the tunability of their band gaps and associated physical properties. Using ab initio density functional theory (DFT), we explore their structural, electronic, mechanical, optical, and thermodynamic behavior. The incorporation of Sn doping significantly improves lattice coefficients and volumes, positively influencing structural responses. The calculated electronic band gaps decrease significantly with increasing Sn doping (up to x = 0.75), ranging from 1.99 eV in the pristine phases to as low as 0.78 eV, indicating enhanced electronic conductivity. Mechanical property analyses, including the Pugh ratio B/G), Poisson ratio (ν), and Cauchy pressure, reveal that BaHf<sub>1-x</sub>Sn<sub>x</sub>S<sub>3</sub> and BaZr<sub>1-x</sub>Sn<sub>x</sub>S<sub>3</sub> exhibit ductile characteristics, whereas CaHfS<sub>3</sub> maintains mechanical stability with a brittle nature. Optical properties evaluated in the 0 to 40 eV energy range display high absorption coefficients, significant optical conductivity, and notable reflectivity, indicating promising optoelectronic performance. Thermodynamic analyses covering Debye temperature, specific heat capacity, entropy, enthalpy, Gibbs free energy, and phonon spectra highlight a transition from thermodynamic instability in pristine structures to enhanced stability upon Sn doping. Overall, the integration of structural tunability, improved electronic and optical performance, and enhanced thermodynamic stability in these chalcogenide perovskites underscores their strong potential for next-generation optoelectronic devices.</div></div>","PeriodicalId":21042,"journal":{"name":"Results in Physics","volume":"77 ","pages":"Article 108462"},"PeriodicalIF":4.6,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145221623","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
This study investigates the use of a surface plasmon resonance (SPR) sensor based on the Kretschmann configuration, featuring a gold coating and a reduced graphene oxide (rGO) sensing layer, for detecting low concentrations of aflatoxin B1. A BK-7 prism, coated with a 50 nm thick gold layer, was employed to induce resonance between incident light and the free electrons in the gold. The addition of a reduced graphene oxide layer on top of the gold further enhanced the sensor’s sensitivity. This enhancement is attributed to the reduction of oxygen groups in the rGO, creating vacancy defects that trap the analyte molecules, particularly aflatoxin B1. Experimental results showed a resonance angle shift corresponding to changes in refractive index, yielding a sensitivity of 700.39°/RIU, a linearity value of 0.9005, and a resolution of 0.6228 ppm. These findings suggest that the Au/rGO-coated SPR sensor holds great promise for detecting mycotoxins such as aflatoxin B1, making it suitable for industrial applications.
{"title":"Enhanced surface plasmon resonance sensor performance using reduced graphene oxide (rGO) layers for aflatoxin detection","authors":"Retna Apsari , Syahidatun Na’imah , Andi Hamim Zaidan , Samian , Masruroh , Sulaiman Wadi Harun , Norhana Arsad , Liaqat Ali , Tarek Mohamed","doi":"10.1016/j.rinp.2025.108461","DOIUrl":"10.1016/j.rinp.2025.108461","url":null,"abstract":"<div><div>This study investigates the use of a surface plasmon resonance (SPR) sensor based on the Kretschmann configuration, featuring a gold coating and a reduced graphene oxide (rGO) sensing layer, for detecting low concentrations of aflatoxin B1. A BK-7 prism, coated with a 50 nm thick gold layer, was employed to induce resonance between incident light and the free electrons in the gold. The addition of a reduced graphene oxide layer on top of the gold further enhanced the sensor’s sensitivity. This enhancement is attributed to the reduction of oxygen groups in the rGO, creating vacancy defects that trap the analyte molecules, particularly aflatoxin B1. Experimental results showed a resonance angle shift corresponding to changes in refractive index, yielding a sensitivity of 700.39°/RIU, a linearity value of 0.9005, and a resolution of 0.6228 ppm. These findings suggest that the Au/rGO-coated SPR sensor holds great promise for detecting mycotoxins such as aflatoxin B1, making it suitable for industrial applications.</div></div>","PeriodicalId":21042,"journal":{"name":"Results in Physics","volume":"77 ","pages":"Article 108461"},"PeriodicalIF":4.6,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145268500","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2025-10-01DOI: 10.1016/j.rinp.2025.108471
Kun Li , Bo Li , Xiaofeng Li , Lei Zhang , Tengfei Wu , Lei Han , Qiang Gao
Measurements of the Lagrangian velocity field in supersonic flows can help to gain a deeper understanding of the internal structure of the flow field, thus supporting aspects of fluid dynamics research and design optimization for engineering applications. However, the measurement technology of the multidimensional Lagrangian velocity field in the supersonic flow field needs to be further improved, especially in the inversion algorithm used to reconstruct the velocity field. Here, we report the two-dimensional Lagrangian velocity field reconstruction of the supersonic flow field by the Femtosecond Laser-Induced Cyano Chemiluminescence (FLICC) technique. The femtosecond laser self-focuses into a filament and then interacts with CH4/N2 gas in the flow field and induces a chemical reaction that generates CN molecular luminescent tagging lines with strong fluorescence intensity and long lifetime. The luminous line moves with the flow in the flow field. The displacement of the luminous line is tracked, and an image of luminous lines is obtained using an Intensified Charge-Coupled Device (ICCD) camera with multiple exposures. Based on the line shapes and displacements of the luminous lines in the image, the luminous lines are discretized into multiple sets of interrelated representation points. These points are then used to calculate the axial and radial velocity components and subsequently reconstruct the 2D velocity field. The relative uncertainty of the axial velocity obtained by this method is 0.11 % in a supersonic flow field with a speed of 530 m/s.
{"title":"Two-dimensional lagrangian velocity field measurement based on femtosecond laser-induced cyano chemiluminescence technique","authors":"Kun Li , Bo Li , Xiaofeng Li , Lei Zhang , Tengfei Wu , Lei Han , Qiang Gao","doi":"10.1016/j.rinp.2025.108471","DOIUrl":"10.1016/j.rinp.2025.108471","url":null,"abstract":"<div><div>Measurements of the Lagrangian velocity field in supersonic flows can help to gain a deeper understanding of the internal structure of the flow field, thus supporting aspects of fluid dynamics research and design optimization for engineering applications. However, the measurement technology of the multidimensional Lagrangian velocity field in the supersonic flow field needs to be further improved, especially in the inversion algorithm used to reconstruct the velocity field. Here, we report the two-dimensional Lagrangian velocity field reconstruction of the supersonic flow field by the Femtosecond Laser-Induced Cyano Chemiluminescence (FLICC) technique. The femtosecond laser self-focuses into a filament and then interacts with CH<sub>4</sub>/N<sub>2</sub> gas in the flow field and induces a chemical reaction that generates CN molecular luminescent tagging lines with strong fluorescence intensity and long lifetime. The luminous line moves with the flow in the flow field. The displacement of the luminous line is tracked, and an image of luminous lines is obtained using an Intensified Charge-Coupled Device (ICCD) camera with multiple exposures. Based on the line shapes and displacements of the luminous lines in the image, the luminous lines are discretized into multiple sets of interrelated representation points. These points are then used to calculate the axial and radial velocity components and subsequently reconstruct the 2D velocity field. The relative uncertainty of the axial velocity obtained by this method is 0.11 % in a supersonic flow field with a speed of 530 m/s.</div></div>","PeriodicalId":21042,"journal":{"name":"Results in Physics","volume":"77 ","pages":"Article 108471"},"PeriodicalIF":4.6,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145221754","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2025-10-01DOI: 10.1016/j.rinp.2025.108460
Mauricio Galvis , Vladimir Ballesteros , Fredy Mesa , Jorge Nisperuza , Johans Restrepo
We report computational micromagnetic simulations of iron nanoparticles with cubic and spherical geometries. The simulations were performed using the open source Ubermag package, which integrates the Object Oriented Micromagnetic Framework (OOMMF) as its computational back-end. All calculations were carried out under free boundary conditions at zero temperature, and the magnetization dynamics was solved through the Landau–Lifshitz–Gilbert (LLG) equation. The Hamiltonian of the system includes four contributions: Zeeman energy, magnetocrystalline anisotropy, demagnetizing energy, and exchange energy.
Our results demonstrate a strong dependence of magnetic responses, specifically coercivity and remanence, on particle size and shape. These quantities are not intrinsic material constants, but are significantly influenced by factors such as geometry and dimensions. The observed trends are explained by the competition among the different energy terms, which collectively minimize the total energy of the system and drive the formation of magnetic domains and domain walls. In addition, the simulations reveal the emergence of complex magnetization textures, including vortex-like states intrinsically linked to the interplay of competing energy contributions. Such textures play a pivotal role in the regulation of the reversal mechanisms and magnetic performance of the nanoparticles, offering deeper insight into the fundamental processes underpinning their magnetization dynamics.
{"title":"Micromagnetic study of iron nanoparticles: Influence of size and shape","authors":"Mauricio Galvis , Vladimir Ballesteros , Fredy Mesa , Jorge Nisperuza , Johans Restrepo","doi":"10.1016/j.rinp.2025.108460","DOIUrl":"10.1016/j.rinp.2025.108460","url":null,"abstract":"<div><div>We report computational micromagnetic simulations of iron nanoparticles with cubic and spherical geometries. The simulations were performed using the open source Ubermag package, which integrates the Object Oriented Micromagnetic Framework (OOMMF) as its computational back-end. All calculations were carried out under free boundary conditions at zero temperature, and the magnetization dynamics was solved through the Landau–Lifshitz–Gilbert (LLG) equation. The Hamiltonian of the system includes four contributions: Zeeman energy, magnetocrystalline anisotropy, demagnetizing energy, and exchange energy.</div><div>Our results demonstrate a strong dependence of magnetic responses, specifically coercivity and remanence, on particle size and shape. These quantities are not intrinsic material constants, but are significantly influenced by factors such as geometry and dimensions. The observed trends are explained by the competition among the different energy terms, which collectively minimize the total energy of the system and drive the formation of magnetic domains and domain walls. In addition, the simulations reveal the emergence of complex magnetization textures, including vortex-like states intrinsically linked to the interplay of competing energy contributions. Such textures play a pivotal role in the regulation of the reversal mechanisms and magnetic performance of the nanoparticles, offering deeper insight into the fundamental processes underpinning their magnetization dynamics.</div></div>","PeriodicalId":21042,"journal":{"name":"Results in Physics","volume":"77 ","pages":"Article 108460"},"PeriodicalIF":4.6,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145221618","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2025-10-01DOI: 10.1016/j.rinp.2025.108445
Maryam Heydari , Hanieh Moghaddasi , Mir Vahid Hosseini , Mehdi Askari
We theoretically investigate current-induced spin polarization in disordered topological insulator thin films with broken inversion symmetry under an applied in-plane electric field. Utilizing the Kubo formalism within the self-consistent Born approximation and incorporating vertex corrections to account for multiple scattering events, we analyze how disorder, chemical potential, the electrostatic potential difference between the top and bottom surfaces, and momentum-dependent hybridization affect the spin susceptibility. Our results reveal that the spin susceptibility exhibits nonzero values within a finite range around a zero gap, and this range broadens as the chemical potential increases. A higher hybridization strength induces asymmetry in the spin response. A stronger potential difference, breaking inversion symmetry, significantly enhances polarization. This enhancement is a trend attributable to band inversion and is further refined by vertex corrections. These findings provide a theoretical framework for tuning spin-charge conversion in topological thin films, with implications for spintronic device applications.
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The possible martensitic transformation (MT) and ductile properties of all-d-metal Ni2MnZ (Z=Sc, Ti, V, Cr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Re, Os, Ir, and Pt) Heusler alloys have been systematically investigated using first-principles calculations. In the cubic austenite, the alloys with Z=Sc, Ti, Y, Zr, Nb, Pd, and Pt possess the ferromagnetic (FM) Cu2MnAl structure, whereas the remaining alloys have the antiferromagnetic (AFM) Hg2CuTi structure. All the thirteen FM alloys, excluding Z=Sc, Y, and Zr, can undergo MT. Compared to Ni2MnTi, most of these alloys display larger transformation strains and higher MT temperatures (). They also demonstrate improved ductility, as indicated by higher Pugh ratios, Poisson’s ratios, and Pettifor’s Cauchy pressures in the austenite. Ni2MnNb alloy may exhibit enhanced elastocaloric, barocaloric, and magnetocaloric effects, accompanied by significant volume and magnetic discontinuities during the MT. It is also revealed that the paramagnetic (PM) ordering promotes MT, enabling it to occur in the PM alloys with Z=Sc, Y, and Zr. Under hydrostatic pressure, the FM Z=Zr alloy can also undergo MT. Mn-Z disorder reduces the driving force for MT, causing it to disappear in Ni2(MnTi)(TiMn) when . The face-centered cubic (FCC) phase tends to precipitate when both the volume and magnetic moment of the structure are smaller than those of the martensite. This precipitation can be accelerated by phonon vibrations, which, nevertheless, further improve the good ductility of the martensite. The insights provide valuable guidance for the experimental design and application of these magnetic shape memory alloys with excellent mechanical properties.
{"title":"Martensitic transformation and good ductility in all-d-metal NiMn-based Heusler magnetic shape memory alloys from first-principles prediction","authors":"Chun-Mei Li, Yu-Tong Liu, Zi-Ran Li, Ren-Zhong Huang","doi":"10.1016/j.rinp.2025.108447","DOIUrl":"10.1016/j.rinp.2025.108447","url":null,"abstract":"<div><div>The possible martensitic transformation (MT) and ductile properties of all-<em>d</em>-metal Ni<sub>2</sub>Mn<em>Z</em> (<em>Z</em>=Sc, Ti, V, Cr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Re, Os, Ir, and Pt) Heusler alloys have been systematically investigated using first-principles calculations. In the cubic austenite, the alloys with <em>Z</em>=Sc, Ti, Y, Zr, Nb, Pd, and Pt possess the ferromagnetic (FM) Cu<sub>2</sub>MnAl structure, whereas the remaining alloys have the antiferromagnetic (AFM) Hg<sub>2</sub>CuTi structure. All the thirteen FM alloys, excluding <em>Z</em>=Sc, Y, and Zr, can undergo MT. Compared to Ni<sub>2</sub>MnTi, most of these alloys display larger transformation strains and higher MT temperatures (<span><math><msub><mrow><mi>T</mi></mrow><mrow><mi>M</mi></mrow></msub></math></span>). They also demonstrate improved ductility, as indicated by higher Pugh ratios, Poisson’s ratios, and Pettifor’s Cauchy pressures in the austenite. Ni<sub>2</sub>MnNb alloy may exhibit enhanced elastocaloric, barocaloric, and magnetocaloric effects, accompanied by significant volume and magnetic discontinuities during the MT. It is also revealed that the paramagnetic (PM) ordering promotes MT, enabling it to occur in the PM alloys with <em>Z</em>=Sc, Y, and Zr. Under hydrostatic pressure, the FM <em>Z</em>=Zr alloy can also undergo MT. Mn-<em>Z</em> disorder reduces the driving force for MT, causing it to disappear in Ni<sub>2</sub>(Mn<span><math><msub><mrow></mrow><mrow><mn>1</mn><mo>−</mo><mi>y</mi></mrow></msub></math></span>Ti<span><math><msub><mrow></mrow><mrow><mi>y</mi></mrow></msub></math></span>)(Ti<span><math><msub><mrow></mrow><mrow><mn>1</mn><mo>−</mo><mi>y</mi></mrow></msub></math></span>Mn<span><math><msub><mrow></mrow><mrow><mi>y</mi></mrow></msub></math></span>) when <span><math><mrow><mi>y</mi><mo>≥</mo><mn>0</mn><mo>.</mo><mn>3</mn></mrow></math></span>. The face-centered cubic (FCC) phase tends to precipitate when both the volume and magnetic moment of the structure are smaller than those of the martensite. This precipitation can be accelerated by phonon vibrations, which, nevertheless, further improve the good ductility of the martensite. The insights provide valuable guidance for the experimental design and application of these magnetic shape memory alloys with excellent mechanical properties.</div></div>","PeriodicalId":21042,"journal":{"name":"Results in Physics","volume":"77 ","pages":"Article 108447"},"PeriodicalIF":4.6,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145221624","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
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