IF 1.9 4区物理与天体物理

Pramana Pub Date : 2024-12-13 DOI: 10.1007/s12043-024-02863-7

Baljinder Kour, Ashish Arora, Deep Singh

引用次数: 0

Precise solution and chaos analysis of a higher-order nonlinear Schrödinger equation in the critical point of surface gravity wave mechanics 表面重力波力学临界点高阶非线性薛定谔方程的精确求解与混沌分析

IF 1.9 4区物理与天体物理

Pramana Pub Date : 2024-11-27 DOI: 10.1007/s12043-024-02853-9

Chuanqi Li

引用次数: 0

Transient features of mass diffusion of MHD slip flow over an unsteady permeable stretching sheet in the presence of a moving free stream, destructive/constructive chemical reaction and variable mass flux 在存在移动自由流、破坏性/建设性化学反应和可变质量通量的情况下，MHD 滑动流在非稳定渗透性拉伸片上的质量扩散瞬态特征

IF 1.9 4区物理与天体物理

Pramana Pub Date : 2024-11-23 DOI: 10.1007/s12043-024-02851-x

Rakesh K R Saha, Hiranmoy Maiti, Swati Mukhopadhyay

{"title":"Transient features of mass diffusion of MHD slip flow over an unsteady permeable stretching sheet in the presence of a moving free stream, destructive/constructive chemical reaction and variable mass flux","authors":"Rakesh K R Saha, Hiranmoy Maiti, Swati Mukhopadhyay","doi":"10.1007/s12043-024-02851-x","DOIUrl":"10.1007/s12043-024-02851-x","url":null,"abstract":"<div><p>An investigation is carried out to explore the combined effects of Thompson–Troian (T–T) slip and variable mass flux on the mass diffusion of unsteady flow of viscous liquid passing a permeable stretched surface. Constructive/destructive chemical reaction has also been considered in this study. In several engineering sectors including aerodynamics, for HVAC (heating, ventilation and air conditioning) systems, it is essential to have a clear idea about the free stream velocity and how to control it. Trusting on this fact, moving free stream is considered here. This, along with the T–T slip, makes the present research distinct. With the help of ‘similarity transformations’, the governing equations along with the conditions at the boundary are transformed to self-similar forms and using fourth-order Runge–Kutta method with shooting technique by the help of bvp4c package in MATLAB software, solutions are obtained numerically. The influences of relevant parameters on the flow, solute distribution, shear stress and concentration at the surface are analysed in detail. Due to enhanced values of unsteadiness, slip and magnetic parameter, flow velocity decreases. Fluid concentration rises for rising strength of the magnetic field and slip whereas increasing unsteadiness causes the fluid concentration to decrease. Flow velocity is boosted up for rising values of velocity ratio parameter. When the slip parameter increases from 0.1 to 0.5, <span>(36.323%)</span> increase in velocity gradient and <span>(8.262%)</span> increase in surface concentration occur. When the slip parameter increases from 0.1 to 0.5, 36.323% increase in velocity gradient and 8.262% increase in surface concentration occur.</p></div>","PeriodicalId":743,"journal":{"name":"Pramana","volume":"98 4","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142691855","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}

引用次数: 0

Pressure-induced iso-structural phase transitions in pyrochlore iridates (A_2hbox {Ir}_2hbox {O}_7) ((A! ,=,)Pr, Gd, Dy and Er) 热绿核铱酸盐（A_2/hbox {Ir}_2hbox {O}_7) ((A!,=,)Pr, Gd, Dy and Er)中压力诱导的等结构相变

IF 1.9 4区物理与天体物理

Pramana Pub Date : 2024-11-23 DOI: 10.1007/s12043-024-02852-w

M Rosalin, Sebabrata Kisku, Prachi Telang, Surjeet Singh, D V S Muthu, A K Sood

{"title":"Pressure-induced iso-structural phase transitions in pyrochlore iridates (A_2hbox {Ir}_2hbox {O}_7) ((A! ,=,)Pr, Gd, Dy and Er)","authors":"M Rosalin, Sebabrata Kisku, Prachi Telang, Surjeet Singh, D V S Muthu, A K Sood","doi":"10.1007/s12043-024-02852-w","DOIUrl":"10.1007/s12043-024-02852-w","url":null,"abstract":"<div><p>We investigated pressure-induced changes in pyrochlore iridates (<span>(A_2hbox {Ir}_2hbox {O}_7)</span>, <span>(A=)</span> Pr, Gd, Dy and Er) using Raman spectroscopy and X-ray diffraction. All four compounds exhibited a pressure-driven isostructural transition associated with the rearrangement of <span>(hbox {IrO}_6)</span> octahedra in the pyrochlore lattice. Interestingly, the critical pressure (<span>(P_textrm{c})</span>) for this transition correlates inversely with the <i>A</i>-site cation radius, <span>(P_textrm{c})</span> decreased from <span>(sim )</span>10.8 GPa (Er, smallest cation) to <span>(sim )</span>7.5 GPa (Pr, largest cation). Additionally, the bulk modulus systematically decreases with increasing ionic radius of <i>A</i>-site across the <span>(A_2hbox {Ir}_2hbox {O}_7)</span> series. High-pressure Raman spectroscopy revealed anomalous decrease of the linewidth with increasing pressure for Ir–O (<span>(T_{2g}^{4})</span>) and Ir–O–Ir (<span>(A_{1g})</span> and <span>(E_g)</span>) vibrational modes, suggesting a suppression of electron–phonon coupling due to enhanced electronic bandwidth under pressure.\u0000</p></div>","PeriodicalId":743,"journal":{"name":"Pramana","volume":"98 4","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142691864","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}

引用次数: 0

Significance of homogeneous–heterogeneous reaction on MHD nanofluid flow over a curvilinear stretching surface 同质异相反应对曲线拉伸表面上 MHD 纳米流体流动的影响

IF 1.9 4区物理与天体物理

Pramana Pub Date : 2024-11-23 DOI: 10.1007/s12043-024-02809-z

Ram Prakash Sharma, Abhishek Sharma, J K Madhukesh, B C Prasannakumara, K V Nagaraja, Raman Kumar

{"title":"Significance of homogeneous–heterogeneous reaction on MHD nanofluid flow over a curvilinear stretching surface","authors":"Ram Prakash Sharma, Abhishek Sharma, J K Madhukesh, B C Prasannakumara, K V Nagaraja, Raman Kumar","doi":"10.1007/s12043-024-02809-z","DOIUrl":"10.1007/s12043-024-02809-z","url":null,"abstract":"<div><p>The current study aims to investigate heat transfer processes in chemically reacting processes, specifically focussing on the flow of an electrically conducting nanofluid over a curved extended surface. The work tries to describe the complex interaction between heat and mass transport phenomena in many applications, such as the biological sciences, catalytic processes and conflagration by including both homogeneous and heterogeneous processes in the framework. Introducing a convective heating strategy is a new technology that may boost circulation phenomena, perhaps leading to improved heat transfer performance. Additionally, the comparison between the Xue and Tiwari–Das models provides helpful insights into their individual suitability and precision in representing the heat transfer mechanism inside the examined system. The boundary layer approximation is used to handle the mathematical equations. Using the proper similarity variables, the controlling partial differential equations (PDEs) are effectively refined into the dimensionless form and computed numerically utilising the Runge–Kutta Fehlberg 4th–5th-order technique. The suggested characteristics of the physical parameters are examined and their relevant behaviour is illustrated graphically. The outcomes declare that the rise in magnetic parameter will decline velocity while enhance thermal profiles. Homogeneous and heterogeneous reaction strengths will decline the mass distribution while heat source/sink, solid fraction and Biot numbers will improve the temperature profile. In all circumstances, the Xue model exhibits a higher rate of thermal dispersion and temperature profile than the Tiwari–Das model.</p></div>","PeriodicalId":743,"journal":{"name":"Pramana","volume":"98 4","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142692011","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}

引用次数: 0

Boosting the structure, thermal, optical and dielectric properties of a thermoplastic polymer by some nanoperovskites 通过一些纳米超微粒子提高热塑性聚合物的结构、热学、光学和介电性能

IF 1.9 4区物理与天体物理

Pramana Pub Date : 2024-11-23 DOI: 10.1007/s12043-024-02850-y

Amani Alruwaili, Adel M El Sayed

{"title":"Boosting the structure, thermal, optical and dielectric properties of a thermoplastic polymer by some nanoperovskites","authors":"Amani Alruwaili, Adel M El Sayed","doi":"10.1007/s12043-024-02850-y","DOIUrl":"10.1007/s12043-024-02850-y","url":null,"abstract":"<div><p>Given their technological applications, nanoperovskites are an intriguing class of multifunctional materials. To exploit their unique features while avoiding some of their shortcomings, developing low-cost and flexible perovskite<span>(/)</span>polymer nanocomposites with enhanced physicochemical properties attracts various research groups. In this report, two different perovskites, lanthanum ferrite nanoparticles (LF NPs) and lead titanate (LT) NPs were obtained by a solid-state route and mixed with a polyvinyl acetate/polyvinyl chloride (PVAc<span>(/)</span>PVC) thermoplastic blend. LF and LT nanostructuration have been investigated by the transmission electron microscope (TEM) and X-ray diffraction (XRD). The NPs’ good dispersion, uniform distribution on the homogeneous film surface and their complexation with the blend chains were clarified by XRD and field emission (FE)-scan electron microscopy (SEM). The Fourier transform infrared (FT-IR) technique identified the influence of these nanoperovskites on the vibrations of the blend’s characteristic (chemical) groups. The thermogravimetric analysis (TGA) also examined the impact of LF and LT NPs on the films' thermal stability. LT NPs are more effective at manipulating the transmission spectra in the UV–vis and IR regions and shrinking the blend’s optical band gap than LF. The study of the dielectric properties showed that the LT/blend had a higher dielectric permittivity, better conductivity (2.72 ×10<sup>−6</sup> S/cm) and higher energy density (0.48 J/cm<sup>3</sup>). The absorption index, dual-band gap nature, dielectric loss and dielectric relaxation in the nanoperovskite/polymer were reported. The findings of this study declare that these nanocomposites are the best candidates for photonic devices and supercapacitor fabrication.</p></div>","PeriodicalId":743,"journal":{"name":"Pramana","volume":"98 4","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142691946","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}

引用次数: 0

The effects of q-deformed Rosen–Morse potential on the behaviour of interacting BEC systems q 变形罗森-莫尔斯势对相互作用的 BEC 系统行为的影响

IF 1.9 4区物理与天体物理

Pramana Pub Date : 2024-11-19 DOI: 10.1007/s12043-024-02844-w

Neslihan Üzar

引用次数: 0

The improved saturation model in the nuclei 改进的原子核饱和模型

IF 1.9 4区物理与天体物理

Pramana Pub Date : 2024-11-19 DOI: 10.1007/s12043-024-02854-8

G R Boroun, B Rezaei

引用次数: 0

Soft drug epidemic in deterministic and stochastic case studies 确定性和随机案例研究中的软性毒品流行问题

IF 1.9 4区物理与天体物理

Pramana Pub Date : 2024-11-09 DOI: 10.1007/s12043-024-02845-9

Islam M Elbaz, M A Sohaly, H El-Metwally

引用次数: 0

A comprehensive analysis of anisotropic stellar objects with quadratic equation of state 具有二次状态方程的各向异性恒星物体的综合分析

IF 1.9 4区物理与天体物理

Pramana Pub Date : 2024-11-09 DOI: 10.1007/s12043-024-02846-8

Kiran Pant, Pratibha Fuloria

{"title":"A comprehensive analysis of anisotropic stellar objects with quadratic equation of state","authors":"Kiran Pant, Pratibha Fuloria","doi":"10.1007/s12043-024-02846-8","DOIUrl":"10.1007/s12043-024-02846-8","url":null,"abstract":"<div><p>The present investigation examines the behaviour of compact relativistic objects characterised by static and spherically symmetric space–time for neutral anisotropic matter distribution. More specifically, we consider an equation of state (EoS), in which density and radial pressure are connected with each other quadratically. By smoothly matching the interior space–time with the exterior at the stellar surface, the appropriate values of the constant parameters for physically realistic solutions are obtained to model various compact stars. We explore the physical behaviour of compact stellar models SMC X-4, Vela X-1, CEN X-3, PSR J1614-2230, LMC X-4 and EXO 1785-248. Further, we describe several features of the compact stellar systems that exhibit physically acceptable attributes with no singularity. All important stability criteria, such as the energy conditions, causality conditions, Buchdhal condition and the adiabatic index are fulfilled by our neutral anisotropic compact star models. An in-depth comprehension of the physical characteristics of the proposed solution has been achieved through meticulous analytical and graphical examinations. By utilising this solution, the masses and radii of six compact stellar candidates mentioned above are optimised with the observed values obtained experimentally. The derived solution might be useful to enhance the understanding of the strong-field regimes and self-gravitating entities.</p></div>","PeriodicalId":743,"journal":{"name":"Pramana","volume":"98 4","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142596096","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}

引用次数: 0

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