Brazilian Journal of Physics最新文献

{"title":"XGBoost Predictions of Heat Generation in MHD Natural Convection of Hybrid Nanofluid in a Wavy Porous Cavity","authors":"Noura Alsedais, Mohamed Ahmed Mansour, Abdelraheem M. Aly","doi":"10.1007/s13538-025-01747-4","DOIUrl":"10.1007/s13538-025-01747-4","url":null,"abstract":"<div><p>This study investigates the effects of heat generation and magnetic fields on natural convection in a wavy porous cavity filled with a hybrid nanofluid (Al₂O₃-Cu/water), using the hybrid finite volume method (FVM) and XGBoost model within the local thermal non-equilibrium (LTNE) framework. The cavity contains inner heaters with variable lengths, positions, and heat generation/absorption coefficients. The primary objective is to analyze the interplay of key parameters, including heat source length (<span>(B)</span>), position (<span>(D)</span>), solid volume fraction (<span>(phi)</span>), porosity (<span>(varepsilon)</span>), Hartmann number (<span>(Ha)</span>), Rayleigh number (<span>(Ra)</span>), and the heat generation/absorption coefficient (<span>(Q)</span>). The results provide insights into optimizing heat and mass transfer characteristics under varying conditions, with potential applications in thermal management systems. The mathematical model incorporates the governing equations for continuity, momentum, and energy for the fluid and solid phases. The LTNE approach accounts for separate temperature fields for the fluid and solid, enabling a detailed analysis of the thermal behavior. The numerical simulations were performed using dimensionless formulations, allowing the study of a wide range of physical and geometric parameters. The cavity geometry includes a wavy right wall maintained at a cold temperature (<span>({T}_{c})</span>) and a flat left wall with localized heat sources (<span>({T}_{h})</span>). The findings reveal the significant influence of <span>(B)</span>, <span>(D)</span>, <span>(phi)</span>, and <span>(Q)</span> on the flow structure and thermal distribution. An increase in <span>(B)</span> intensifies convective currents and enhances heat transfer efficiency, while the position of the heat source (<span>(D)</span>) modulates the distribution of buoyancy forces. The addition of nanoparticles (<span>(phi)</span>) improves the effective thermal conductivity of the hybrid nanofluid, enhancing both fluid and solid phase heat transfer. Positive values of <span>(Q)</span> further amplify buoyancy-driven convection, resulting in higher Nusselt numbers (<span>(Nu)</span>). The impact of porosity (<span>(varepsilon)</span>) and Rayleigh number (<span>(Ra)</span>) was also evaluated. Higher porosity values promote fluid permeability, facilitating stronger convective currents and more uniform temperature profiles. Similarly, increasing <span>(Ra)</span> shifts the dominant heat transfer mechanism from conduction to convection, enhancing thermal mixing and efficiency. The Hartmann number (<span>(Ha)</span>) was found to suppress convection due to magnetic damping effects, reducing heat transfer rates. However, this damping can be partially offset by the enhanced thermal conductivity from higher nanoparticle concentrations (<span>(phi)</span>). AI-based models, specifically XGBoost, were employed to predict the Nusselt number f","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 3","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143698642","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}

{"title":"Correction: Spin-Gapless Quaternary Heusler Alloys IrCoTiZ (Z = Si, Sn, Pb): Exploring New Opportunities in Spintronics, Optoelectronics, and Thermoelectrics","authors":"A. Khatar, B. Bouadjemi, M. Houari, M. Matougui, T. Lantri, K. Khelifa-Kerfa, S. Bentata, S. Haid, M. H. Cherif, A. Messaoudi, S. Mesbah","doi":"10.1007/s13538-025-01752-7","DOIUrl":"10.1007/s13538-025-01752-7","url":null,"abstract":"","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 3","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143688459","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}

{"title":"Integrated Dynamics of Eco-Epidemic Systems: Nonlinear Prey Refuge, Predator Exploitation, Fear Impact, and Infection Control","authors":"Md Sarijul Islam,&nbsp;Bapin Mondal,&nbsp;Sahabuddin Sarwardi","doi":"10.1007/s13538-025-01744-7","DOIUrl":"10.1007/s13538-025-01744-7","url":null,"abstract":"<div><p>The article investigates an eco-epidemic predator-prey model, where only the prey population becomes infected. Both the prey populations take nonlinear prey refuge with different coefficients to protect themselves from their predator. Fear of predators reduces the growth rate and activity of the prey population, which in turn reduces the rate of disease transmission. The model system incorporates treatment for infected individuals. After formulation of the model system, some preliminary results of the system are executed and followed by system’s points of equilibrium. We have calculated the basic reproduction number that holds a crucial role in determining the eradication of disease from the system. Analysis of the system’s bifurcation with respect to different crucial parameters is executed. By increasing the value of treatment parameters to a certain extent, it is found that the disease can be eradicated from the system. Further, Pontryagin’s maximum principal is used to optimize the disease control. Some numerical simulations illustrate and validate the obtained results.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 3","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143688274","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}

{"title":"Correction: Combined Impacts of Self-Generated and Non-uniform Magnetic Fields on the Acceleration of Plasma Electrons","authors":"Mehdi Abedi-Varaki,&nbsp;Bahman Zohuri","doi":"10.1007/s13538-025-01756-3","DOIUrl":"10.1007/s13538-025-01756-3","url":null,"abstract":"","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 3","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143688460","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}

{"title":"The Aspects of (^{12}textrm{C}(p, gamma )^{13}textrm{N}) Reaction in Astrophysical Regime","authors":"Soumya Saha","doi":"10.1007/s13538-025-01745-6","DOIUrl":"10.1007/s13538-025-01745-6","url":null,"abstract":"<div><p>The carbon-nitrogen-oxygen (CNO) cycle is fundamental to the process of hydrogen burning in stars, serving as a pivotal mechanism. At its core, the primary reaction involves the radiative capture of a proton by <span>( ^{12}textrm{C} )</span>, which crucially influences the isotopic ratio of <span>( ^{12}textrm{C} )</span> to <span>( ^{13}textrm{C} )</span> observed in celestial bodies, including our Solar System. To address this, we applied the astrophysical <span>(R)</span>-matrix approach to extrapolate low-energy cross sections and S-factors, thereby improving the precision of nuclear reaction rates. At a proton energy of around 25 keV (C.M. system), the extrapolated value of the astrophysical S-factor is determined to be <span>( 1.34 pm 0.10 , mathrm {keV , barn} )</span>. Our investigation sheds light on its implications for nuclear reaction rates, suggesting that at low temperatures in hydrogen-burning sites, the conversion of <span>( ^{12}textrm{C} )</span> to <span>( ^{13}textrm{C} )</span> via proton capture is relatively slow, thereby influencing the abundance ratios in the cosmic environment. This slow conversion affects stellar nucleosynthesis and isotopic evolution, particularly in low-mass stars <span>((M le 2 , M_odot ))</span> where hydrogen burning proceeds at relatively low temperatures. Unlike previous analyses with large uncertainties at low energies, our approach refines the S-factor determination by incorporating improved ANC (Asymptotic Normalization Constant) values, reducing extrapolation uncertainties.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 3","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143667971","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}

{"title":"Study of the 10B(d,3He)9Be Reaction at a Deuterons Energy of 14.5 MeV","authors":"Sayabek Kuanyshbekovich Sakhiyev,&nbsp;Maulen Nassurlla,&nbsp;Nurzhan Orynbasarovich Saduyev,&nbsp;Nassurlla Burtebayev,&nbsp;Stanislav Borisovich Sakuta,&nbsp; Marzhan Nassurlla,&nbsp;Romazan Akhmedzhanovich Khojayev,&nbsp;Karashash Aidaralyevna Talpakova,&nbsp;Aiken Nurpeisov,&nbsp;Damir Asankhanuly Issayev","doi":"10.1007/s13538-025-01748-3","DOIUrl":"10.1007/s13538-025-01748-3","url":null,"abstract":"<div><p>At a deuteron energy of 14.5 MeV, the ¹⁰B(<i>d</i>,³He)⁹Be reaction was examined. A series of experiments were carried out to investigate the reaction dynamics and excitation properties of the ⁹Be nucleus. In particular, measurements of cross-sections for transitions to its ground state (3/2⁻) and an excited state at an energy of 2.429 MeV (5/2⁻) were conducted. Using the coupled channel method for angular distributions analysis, the derived spectroscopic amplitude values were <i>SA</i> = 0.71 ± 0.15 and <i>SA</i> = 0.82 ± 0.15. These results align well with prior theoretical and experimental outcomes, considering the inherent uncertainties in the data. Additionally, investigations of the (<i>d</i>, <i>t</i>) reaction on ¹⁰B revealed that transitions to the ⁹B nucleus at corresponding energy levels yield spectroscopic amplitude values of <i>SA</i> = 0.67 ± 0.1 for its ground state and <i>SA</i> = 0.94 ± 0.2 for an excited state at 2.361 MeV (5/2⁻). The congruence the results of the analysis the mirror (<i>d</i>, ³He) and (<i>d</i>, <i>t</i>) reactions emphasizes the charge-independent nature of their mechanisms.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 3","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143655412","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}

{"title":"Interaction of Gardner Dust Ion-Acoustic Multiple Solitons in a Dusty Plasma: Insights from Cassini Observations","authors":"Nazia Batool,&nbsp;W. Masood,&nbsp;M. Siddiq,&nbsp;Weaam Alhejaili,&nbsp;L. S. El-Sherif,&nbsp;Samir A. El-Tantawy","doi":"10.1007/s13538-025-01724-x","DOIUrl":"10.1007/s13538-025-01724-x","url":null,"abstract":"<div><p>This study investigates the complex dynamics of dust ion-acoustic waves (DIAWs) in a non-Maxwellian plasma, comprising stationary negatively charged dust grains, dynamical positive ions, and inertialess hot Maxwellian electrons and cold generalized (<i>r</i>, <i>q</i>)-distributed electrons. Our investigation is motivated by observations of the Cassini spacecraft in Saturn’s magnetosphere. We aim to analyze the formation and interaction of multiple solitons within this plasma system by employing the reductive perturbation method (RPM) to reduce the fluid equations to the Gardner equation (GE). Subsequently, Hirota’s bilinear method is applied to obtain the multiple soliton solutions for the GE. This study is the first to explore the existence of multiple soliton solutions within the GE framework in a plasma context. Consequently, it will gain a commendable standing among several researchers studying fluids, explicitly focusing on plasma physics. Furthermore, we examine the influence of the nonthermal population of electrons on soliton propagation and their interaction. The findings presented in this paper provide valuable insights into the behavior of dust ion-acoustic (DIA) Gardner solitons in space plasmas and offer a comprehensive analysis of their interaction dynamics. This study is anticipated to pave the way for other researchers to investigate the dynamical scenario of the propagation and interaction of multiple soliton waves in various plasma systems.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 3","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143655351","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}

{"title":"Combined Impacts of Self-Generated and Non-uniform Magnetic Fields on the Acceleration of Plasma","authors":"Mehdi Abedi-Varaki,&nbsp;Bahman Zohuri","doi":"10.1007/s13538-025-01742-9","DOIUrl":"10.1007/s13538-025-01742-9","url":null,"abstract":"<div><p>In the present study, the combined impacts of self-generated and non-uniform magnetic fields on the acceleration of plasma electrons using circularly polarized laser pulses propagating in plasma are theoretically studied under a strongly relativistic regime. Analytical and mathematical formulations for analyzing laser pulse propagation through plasma medium with consideration of the self-generated and non-uniform magnetic fields have been obtained. The simulation results show that in comparison to without a non-uniform magnetic field, electron energy increases with an increasing <i>δ</i>-parameter. Additionally, it is recognized that the existence of both non-uniform as well as self-generated magnetic fields simultaneously increases electron transverse momentum, which increases energy. Furthermore, it is observed that when the plasma is only dominated via the self-generated magnetic fields consisting of azimuthal and axial magnetic fields, plasma electrons accelerate much less than when a non-uniform magnetic field is employed. It is also shown that higher laser intensity results in a rise in electron energy, depending on the optimal laser field and self-consistent magnetic field. Moreover, it is realized that the amounts of the slope parameter and the magnetic field can be adjusted to control electron energy gain.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 3","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143655347","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}

{"title":"Exploring the Structural, Optoelectronic, Transport, and Radiation Shielding Capabilities of Al-based Chalcogenides for Energy Technologies: Spin Polarized Approach","authors":"Muhammad Irfan,&nbsp;Ali Zaheer,&nbsp;Fatma A. Ibrahim,&nbsp;Mohamed S. Hamdy,&nbsp;Norkulov Uchkun Munavvarovich,&nbsp;Shams A. M. Issa,&nbsp;Hesham M. H. Zakaly","doi":"10.1007/s13538-025-01746-5","DOIUrl":"10.1007/s13538-025-01746-5","url":null,"abstract":"<div><p>Chalcogenides represent a versatile class of materials with diverse properties, enabling their application in a broad range of technologies, including solar cells, LEDs, superconductors, magneto-resistive devices, and topological insulators. In this study, the structural, electronic, optical, phononic, and radiation-related properties of XAl₂S₄ (X = Eu, Fe, Rh) compounds were investigated using first-principles density functional theory (DFT). The electronic properties reveal a semiconducting nature with bandgaps in the range of 1.2–3.4 eV. The computed negative formation energy and phonon calculations confirm phase stability. Analysis of the density of states highlights the specific electronic states contributing to the band structure. The density of states (DOS) analysis for XAl₂S₄ (X = Eu, Fe, Rh) compounds identifies the electronic states contributing to the band structure. The valence band is mainly influenced by S-3p orbitals and X-d states, while the conduction band is predominantly shaped by Al-3p and X-d orbitals. The interaction between X-d and S-3p states plays a significant role in defining the bandgap and electronic transitions. These findings highlight the key contributions of localized and hybridized states in determining the semiconducting nature of these materials, with bandgaps ranging from 1.2 to 3.4 eV. Optically, the reflectivity remains around 30% below 12.0 eV and reaches a maximum of 32% at approximately 13.0 eV. The compounds demonstrate strong potential for radiation shielding, attributed to their high-density elements and effective absorption properties. Notably, the strong optical anisotropy of these materials suggests their potential for polarization-sensitive photodetector applications. The Seebeck coefficient is positive, indicating the properties of a p-type semiconductor with the highest power factor is approximately 2.0 × 10¹¹ W m⁻¹ K⁻². At 600 K, the thermoelectric figure of merit ZT reaches its maximum value of 1.2. These findings indicate that XAl₂S₄ compounds are promising candidates for optoelectronic devices and LED technologies, particularly as green phosphors for energy applications. Radiation shielding analysis reveals that the EuAl₂S₄ compound achieves a mass attenuation coefficient of 0.145 cm²/g at 1 MeV, surpassing conventional materials like lead-based shields in low-energy regimes.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 3","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143645458","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}

{"title":"Thermal, Optical, and Structural Properties of Eu3+-Doped TiO2 Nanophosphors","authors":"Nand Kumar Shante,&nbsp;Aastha Sahu,&nbsp;Mohan Awasthi,&nbsp;Pankaj Kumar Mishra,&nbsp;R. P. Patel","doi":"10.1007/s13538-025-01736-7","DOIUrl":"10.1007/s13538-025-01736-7","url":null,"abstract":"<div><p>Eu³⁺-doped TiO₂ nanophosphors were synthesized using the co-precipitation method and characterized for structural, optical, and thermoluminescent (TL) properties. X-ray diffraction (XRD) analysis confirmed the anatase phase with crystallite sizes ranging from 19.47 to 28.05 nm. UV–Vis spectroscopy revealed a redshift on doping Eu³⁺ which causes a decrease in the optical band gap from 3.73 eV (pure TiO₂) to 3.44 eV (Eu-doped samples) as defect states introduced by europium ions. Raman and FTIR spectroscopy confirmed the structural integrity and vibrational modifications induced by Eu³⁺ doping. Thermoluminescence studies exhibited a prominent glow peak at 287 °C for TiO₂ doped with 3 mol % Eu³⁺, with quenching at higher doping levels due to the saturation of trapping centres. The activation energy of TL glow peaks is calculated using peak shape methods, ranging from 0.732 to 0.818 eV, indicating the presence of deep trap levels. The frequency factor varied between 2.78 × 10⁷ s⁻¹ and 1.68 × 10⁸ s⁻¹, suggesting a thermally stable trapping mechanism. The relatively low activation energy highlights the potential of Eu³⁺-doped TiO₂ as a rapid-response sensor material, suitable for radiation dosimetry and optoelectronic applications. These findings demonstrate that controlled Eu³⁺ doping can enhance the luminescence efficiency and thermal stability of TiO₂ nanophosphors, making them promising candidates for advanced sensing and display application.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 3","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143632488","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}