Pramana最新文献

{"title":"Thermal analysis of the bio-convective magnetised retardation-type nanofluid flow over a bidirectional sinusoidal moving surface having radiative effects","authors":"Ahmed S Sowayan,&nbsp;Samaira Aziz,&nbsp;Sami Ullah Khan,&nbsp;Nadia Imtiaz,&nbsp; Adnan,&nbsp;Arshad Riaz,&nbsp;Hakim Al Garalleh","doi":"10.1007/s12043-025-02908-5","DOIUrl":"10.1007/s12043-025-02908-5","url":null,"abstract":"<div><p>The nonlinear unsteady flows restricted by moving surfaces have gained particular significance in numerous technological, engineering, industrial, mechanical and biological processes. The flow caused by oscillatory stretched surfaces has attracted particular attention due to its fascinating properties, such as in fluidic oscillators, oscillating jets, oscillation problems, etc. Nanofluids have recently gained much attention due to their potential in numerous applications across various industries. The primary use of the nanomaterials is to increase the effectiveness of heat transfer in various systems. Due to the importance of biomaterial’s in different industrial, technological and engineering systems, the process of bioconvection in nanomaterials has attained reputation in recent years. To lead this exploration, an unsteady bio-convective flow of Oldroyd-B nanomaterial across a bi-directional oscillatory stretched surface is investigated here. Heat generation and thermic radiation have been employed to inspect heat transfer attributes. Furthermore, the effects of magnetic force, chemical reaction and activation energy were employed for the whole analysis. Apposite makeovers were used to convert the deduced nonlinear system to non-dimensional expressions. To yield the series solution, an analytic procedure, namely the homotopy analysis technique (HAM) was adopted. Various graphs were plotted to deliberate the effects of the associated variables on concentration, micro-organism, velocities and temperature profiles. Numeric data were organised in different tables to discuss the importance of different variables on the motile density, local Nusselt and local Sherwood numbers. It has been observed that bidirectional velocities display opposite trends for relaxation and retardation variables. It has further been perceived that amplitudes of velocities periodically decelerate for increase in Hartman number. Greater estimations of heat generation, Brownian motion, thermophoresis and thermic radiation effectively improve the temperature within the nanofluid whereas it diminishes by varying the Prandtl number. Concentration profile declined with Schmidt number, reaction rate and temperature difference variables, while opposite scenario occurred for thermophoresis and activation energy parameters. Moreover, distribution of micro-organisms’ increases for Hartmann number but drops because of greater estimates of the micro-organisms concentration difference, bio-convective Peclet and Lewis numbers.</p></div>","PeriodicalId":743,"journal":{"name":"Pramana","volume":"99 2","pages":""},"PeriodicalIF":1.9,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143821938","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":"Research on stochastic resonance method in fractional-order tristable systems","authors":"Qiang Ma,&nbsp;Ran Peng,&nbsp;Zhichong Wang,&nbsp;Kai Yang","doi":"10.1007/s12043-025-02901-y","DOIUrl":"10.1007/s12043-025-02901-y","url":null,"abstract":"<div><p>We introduce an innovative approach to fractional-order tristable stochastic resonance (SR), utilising the advantages of temporal memory and spatial correlation inherent in fractional-order systems while harnessing the non-saturating properties of tristable SR mechanisms. First, we derived the fractional-order tristable Langevin equation and studied the SR phenomenon within this system across key parameters, such as the fractional-order <i>α</i>, system parameters and external periodic force, within the <i>α</i> range of (0,2]. We identified the optimal resonance region through this analysis. Second, to achieve adaptive fractional-order SR and effectively handle high-frequency and experimental signals, we introduced a standard scale transformation method along with the butterfly optimisation algorithm. Finally, through verification with simulation signals, laboratory data and experimental data from the outer race fault of an aircraft engine’s intermediate shaft bearing, we demonstrated that our proposed method could efficiently extract weak fault characteristic signals from environments with strong noise. Comparative analysis with traditional tristable SR methods and the empirical mode decomposition algorithm showed that signals extracted using our method exhibited larger characteristic frequency amplitudes and higher signal-to-noise ratios (SNR).</p></div>","PeriodicalId":743,"journal":{"name":"Pramana","volume":"99 2","pages":""},"PeriodicalIF":1.9,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143821917","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":"Confinement impacts of magnetic field on beryllium atom, ions and isoelectronic ions embedded in various plasma environments","authors":"Salah Doma,&nbsp;Gamal Roston,&nbsp;Mostafa Ahmed","doi":"10.1007/s12043-025-02899-3","DOIUrl":"10.1007/s12043-025-02899-3","url":null,"abstract":"<div><p>Using the variational Monte Carlo method, a first-time investigation is made for the beryllium atom, ions and isoelectronic ions within three plasma environments confined by an external homogeneous magnetic field. The study focusses on the excited singlet and triplet states included in this work, which are the low-lying excited states (1<i>s</i>²2<i>s</i>2<i>p</i>, 1<i>s</i>²2<i>s</i>3<i>s</i> and 1<i>s</i>²2<i>s</i>3<i>p</i>) and the core excited states (1<i>s</i>2<i>s</i>²3<i>s</i> and 1<i>s</i>2<i>s</i>3<i>s</i>²), utilising plasma potentials, such as the screened Coulomb (SCP), exponential cosine screened Coulomb (ECSCP) and Hulthén potentials. Energy eigenvalues are determined using appropriate trial wave functions, which account for electron–electron repulsion and spin parts to adhere to the Pauli exclusion principle. Moreover, two effective factors related to the wave function of the magnetic field and the ECSCP model are considered. The results reveal an intriguing relative ordering for the lithium atom using the three plasma models, with many of the findings being novel contributions yet to be explored.</p></div>","PeriodicalId":743,"journal":{"name":"Pramana","volume":"99 2","pages":""},"PeriodicalIF":1.9,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143821918","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":"Multiple regression analysis of the Blasius and Sakiadis flow of the power-law nanofluid over a moving thin needle","authors":"Palani Sathya,&nbsp;Padigepati Naveen,&nbsp;Kuppalapalle Vajravelu","doi":"10.1007/s12043-025-02903-w","DOIUrl":"10.1007/s12043-025-02903-w","url":null,"abstract":"<div><p>Fluid flow over a thin moving needle surrounded by a nanofluid has recently gained attention due to its application in science and technology. Hence, the current investigation aims to analyse a power-law nanofluid flow along a thin needle and make a comparative analysis with Blasius and Sakiadis flow problems. The Buongiorno nanofluid model is used to study the influences of thermophoresis and Brownian motion. Using a Bvp4c method, the dimensionless governing equations of the model are solved. The findings indicate that the power-law index and the needle thickness reduce the velocity field in the Blasius flow, but quite the opposite trend is observed in the Sakiadis flow. In the Sakiadis flow, the temperature and the concentration fields dominate over the Blasius flow. In addition, regression analysis is employed to acquire deeper insight into the engineering quantities. The thermal transmission rate increased in the Sakiadis flow compared to that in the Blasius flow with an increase in the Brownian motion parameter. The study outcomes will help us understand the theoretical concepts behind applications, such as hot wire anemometers, targeted drug delivery, cancer treatment, micro-cooling systems and medical equipments such as dialysis machines, biopsy, infusion pumps, medical implant design.\u0000</p></div>","PeriodicalId":743,"journal":{"name":"Pramana","volume":"99 2","pages":""},"PeriodicalIF":1.9,"publicationDate":"2025-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143778025","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":"Statistical measures on digital phase generation and transmission through alkali-metal vapours: a tutorial study","authors":"Abu Mohamed Alhasan,&nbsp;Salah Abdul rhmann","doi":"10.1007/s12043-025-02894-8","DOIUrl":"10.1007/s12043-025-02894-8","url":null,"abstract":"<div><p>This paper explores the statistical measure features of digital phase transfer among multilevel atoms, such as alkali metals with hyperfine structures. The excitation fields constitute a train of probe pulses and a single drive field. We have provided two schemes for the mechanism of excitation dynamics. In the first scheme, the pulses are frequency swept across the upper hyperfine splitting of the excited atomic states. In the second scheme, the pulses are tuned to the upper hyperfine level with a high angular momentum, allowing strong absorption of pulses. The phases of the propagating pulses are rectangular shapes with well-separated boundaries, especially in the second scheme. We address the notion of phase entropy to study the influence of sweeping on the statistics of the generated phases and select definite phases with desired features. The estimated phase entropy exposes local maximum entropy and minimum entropy. In the second scheme, we have extended the pulses in time. Therefore, the phase distributions are rich. The features of the digital distributions of rectangular phases have not been obtained manually. We have addressed math criteria to distinguish the digital phase’s features across propagation. Randomness tests and randomness generation have been evaluated on the time-dependent discrete phase sequences. We expect the proposed generation and transmission of randomised discrete phases to be used in quantum applications.</p></div>","PeriodicalId":743,"journal":{"name":"Pramana","volume":"99 2","pages":""},"PeriodicalIF":1.9,"publicationDate":"2025-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143668355","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":"Entrance channel-dependent compound nucleus formation probability of heavy nuclei","authors":"H S Anushree,&nbsp;S Shubha,&nbsp;H C Manjunatha,&nbsp;N Sowmya","doi":"10.1007/s12043-025-02900-z","DOIUrl":"10.1007/s12043-025-02900-z","url":null,"abstract":"<div><p>Compound nucleus (CN) formation probability (<span>(P_{textrm{CN}})</span>) is essential for synthesising superheavy elements (SHEs), understanding nuclear reactions, predicting reaction outcomes and designing efficient experiments. High <span>(P_{textrm{CN}})</span> indicates a greater likelihood of successful fusion, aiding in the study of nuclear stability and structure. An empirical formula for <span>(P_{textrm{CN}})</span> has been proposed, incorporating new parameters such as effective fissility (<span>(chi _{textrm{eff}})</span>) and zeta parameter (<span>(zeta )</span>), along with excitation energy and fusion barrier height. The fitted function shows greater systematic behaviour for <span>((E^*-V_B)chi _{textrm{eff}})</span> and <span>(zeta ^{0.02})</span>. <span>(P_{textrm{CN}})</span> values obtained align well with the experimental data, predicting outcomes for both successful and unsuccessful fusion reactions. Notably, larger <span>(P_{textrm{CN}})</span> values are seen for <span>(phantom {a}^{45}hbox {Sc}{+}^{249}hbox {Cf})</span> and <span>(phantom {a}^{50}hbox {Ti}{+}^{249}hbox {Bk})</span> for <span>(Z=119)</span> and 120, respectively. Analysis identifies <span>(phantom {a}^{80}hbox {Se}{+}^{210}hbox {At})</span> and <span>(phantom {a}^{55}hbox {Mn}{+}^{241}hbox {Pu})</span> as potential reactions for synthesising the SHE (<span>(Z=119)</span>), with Mn projectiles showing higher <span>(P_{textrm{CN}})</span> than Se projectiles due to lower <span>(zeta )</span> and deformation effects. Hence, <span>(phantom {a}^{55}hbox {Mn}{+}^{241}hbox {Pu})</span> is more promising than <span>(phantom {a}^{80}hbox {Se}{+}^{210}hbox {At})</span> for this purpose. The present work is useful for focussing experimental efforts and increasing the efficiency of SHE research by focussing on reactions with higher CN formation probability.</p></div>","PeriodicalId":743,"journal":{"name":"Pramana","volume":"99 2","pages":""},"PeriodicalIF":1.9,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143645544","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":"Non-classical properties of coherent light interacting with two harmonic modes coupled through the angular momentum","authors":"Kartick Chandra Saha,&nbsp;Dolan Krishna Bayen,&nbsp;Swapan Mandal","doi":"10.1007/s12043-025-02896-6","DOIUrl":"10.1007/s12043-025-02896-6","url":null,"abstract":"<div><p>The dynamical solutions of two quantised harmonic modes coupled through the angular momentum are used to study the photon antibunching (PA) and the amplitude squared squeezing (ASS) of the input coherent radiation field interacting with the said coupled two oscillators. The analytical closed-form expressions for the PA and the ASS are exhibited. The complicated nature of the exact analytical solutions are on the way of extracting good physics. Therefore, the parametric estimates for the ASS and the PA are exhibited. A small algebra shows that the coupling parameter is of two parts. One of the two parts is responsible for the quantum optical properties of the input radiation field. Interestingly, the PA is obtained even when both the harmonic modes are in vacuum. It substantiates the fact that the coupling parameter induces nonlinearity and hence the photons are generated out of the vacuum. The data chosen for the symbolic calculations are theoretical in nature. Of course, these data are quite consistent with those of the theoretical developments. Apart from the academic interests of the present investigation, it is possible to plan a real experiment to verify the analytical results.</p></div>","PeriodicalId":743,"journal":{"name":"Pramana","volume":"99 2","pages":""},"PeriodicalIF":1.9,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143638533","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 dynamic analysis of the complex negative-order Ablowitz–Kaup–Newell–Segur equation using the localised wave structures","authors":"Kai-Hong Yao,&nbsp;Xiao-Yong Wen","doi":"10.1007/s12043-024-02890-4","DOIUrl":"10.1007/s12043-024-02890-4","url":null,"abstract":"<div><p>A complex negative-order Ablowitz–Kaup–Newell–Segur (AKNS) equation, which has potential utility in characterising the propagation of femtosecond pulses through erbium-doped fibre, is studied in this paper. The complex negative order AKNS equation’s <span>((n, N-n))</span>-fold extended Darboux transformation (DT) is established by considering its recognised <span>(2times 2)</span> matrix Lax pair. The equation’s soliton and breather solutions can be obtained by utilising the resulting DT. By asymptotic analysis, we are able to illustrate and discuss the soliton’s elastic interaction graphically and to analyse some significant dynamic features, such as wave velocity, amplitude and energy. Meanwhile we also study the rogue wave and mixed breather-rogue wave interaction solutions. Finally, the numerical simulations of one- and two-soliton solutions are performed to analyse their dynamical structures. The implications and characteristics discussed in this work can be useful in understanding the propagation of optical pulses.</p></div>","PeriodicalId":743,"journal":{"name":"Pramana","volume":"99 2","pages":""},"PeriodicalIF":1.9,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143638534","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":"Gravity-driven thermally stratified nanofluid flow past a permeable stretching surface","authors":"Saheb Konai,&nbsp;Swati Mukhopadhyay","doi":"10.1007/s12043-025-02895-7","DOIUrl":"10.1007/s12043-025-02895-7","url":null,"abstract":"<div><p>This study offers an analysis of the gravity-driven thermally stratified laminar nanoliquid flow past a permeable stretching surface with vanishing flux of nanoparticles. Two-phase fluid model is used for the nanofluids. By the application of similarity transformations, the partial differential equations (PDEs) that govern the problem are converted to ordinary differential equations (ODEs) which are extremely nonlinear. By using the shooting technique and Runge–Kutta (R–K) method, those equations are numerically solved. Shear stress at the surface and rate of surface mass transfer decrease but rate of heat transport at the surface rises for the enhancement of mass transpiration parameter. Temperature and concentration of the nanofluid are found to fall, but the liquid’s velocity rises with the rising buoyancy parameter. Concentration of the nanofluid increases but velocity of the liquid and temperature diminish when the thermal stratification parameter increases.\u0000</p></div>","PeriodicalId":743,"journal":{"name":"Pramana","volume":"99 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143594812","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":"Charged relativistic model utilising embedding condition and quadratic equation of state","authors":"Alberto K Mathias,&nbsp;Avirt S Lighuda","doi":"10.1007/s12043-025-02898-4","DOIUrl":"10.1007/s12043-025-02898-4","url":null,"abstract":"<div><p>The exact solution for the Einstein–Maxwell field equations is generated. The quadratic equation of state together with the Karmarkar condition are used to investigate the structure and properties of the relativistic stars. The Karmarkar condition provides the relationship between the two gravitational potentials. The process of combining the Karmarkar condition and an EoS has currently led to new realistic solutions. In generating the model, one of the gravitational potentials is specified on physical grounds. The generated model undergoes several physical tests to determine its validity and acceptability. Several realistic physical conditions are found to be satisfied. The model stability regarding the adiabatic index and equilibrium of the physical forces is satisfied. The mass–radius relationship and surface red-shift both increase monotonically and are within the acceptable range of a realistic model. Their parameter values are found to be compatible with observations. The gravitational potentials are continuous throughout the star’s interior, and the model’s energy conditions are also satisfied.</p></div>","PeriodicalId":743,"journal":{"name":"Pramana","volume":"99 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143594813","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}