Article
Astronomy & Astrophysics
Matthias Diez, Reinhard Alkofer, Christian Kohlfuerst
Summary: Particle production by ultra-strong electric fields is a well-studied research field, but the formation time of a particle remains mysterious. In this study, we provide an interpretation of a particle distribution at finite times and identify the relevant time scales for particle formation in quantum physics within and beyond perturbation theory.
Article
Computer Science, Interdisciplinary Applications
Hiroaki Nishikawa
Summary: In this short note, the authors discuss the potential failure to observe the design order of discretization error convergence in accuracy verification when solving a time-dependent problem. They highlight the issue of failing to observe the design order of spatial accuracy with a small time step and emphasize that the problem persists even with grid refinement. This note clarifies the mechanism causing this failure and provides guidance for avoiding such pitfalls.
JOURNAL OF COMPUTATIONAL PHYSICS
(2023)
Article
Optics
Pavel Peterka, Artur O. Slobodeniuk, Tomas Novotny, Pawan Suthar, Miroslav Bartos, Frantisek Trojanek, Petr Maly, Martin Kozak
Summary: We experimentally investigate nonperturbative high harmonic generation (HHG) in monolayer MoS2 in the ultraviolet spectral region driven by mid-infrared light. The HHG is influenced by pre-excitation of the monolayer using resonant and near-resonant pulses. The presence of pre-excited carriers suppresses HHG due to ultrafast dephasing caused by electron-electron scattering. Near-resonant excitation with photon energy below the exciton transition shows a fast component in the suppression of HHG yield, which is a consequence of momentum scattering at carriers excited by two-photon transition.
Article
Physics, Applied
Muhammad Ibrahim, E. Al Sarairah, Hala A. A. Hejazi, Tareq Saeed
Summary: In this paper, the time-dependent viscous fluid flow along a stretching horizontal plate with a magnetic field is investigated, considering viscous dissipation and chemical reaction. The flow problem is governed by a system of partial differential equations (PDEs). By using dimensionless variables, the governing PDEs are transformed to a dimensionless form. The finite difference method is adopted to numerically solve the system of PDEs with given initial and boundary conditions. The impact of potential variables is examined and displayed graphically. The results show that higher Hartmann number decreases velocity and temperature, while increasing the chemical reaction parameter decreases concentration profile. Moreover, the skin friction increases with higher Hartmann number values and Nusselt number, showing an increase with higher Eckert and Prandtl numbers.
INTERNATIONAL JOURNAL OF MODERN PHYSICS B
(2023)
Article
Physics, Multidisciplinary
Lei Du, Yao-Tong Chen, Yan Zhang, Yong Li
Summary: In this paper, we study the decay dynamics of a two-level giant atom coupled to a waveguide with time-dependent coupling strengths. In the non-Markovian regime, we find that the dynamics of the atom depend on the atom-waveguide coupling strengths at an earlier time, allowing for tailored decay dynamics and the possibility of stationary population revival. Additionally, we demonstrate the potential to simulate quantum Zeno and anti-Zeno effects in the giant-atom model with periodic coupling quenches.
PHYSICAL REVIEW RESEARCH
(2022)
Article
Physics, Multidisciplinary
Salman Ahmad, Habib Ullah, T. Hayat, Mohammed Sh Alhodaly
Summary: This study investigates the time-dependent convective flow of non-Newtonian power-law fluid by a vertical plate, considering thermal radiation effects. The Buongiorno model is used for nanofluid characteristics, while entropy generation and Bejan number are calculated. The system of partial differential equations is solved in dimensionless form using finite difference technique, with a focus on various parameters such as Prandtl number and Reynolds number. Graphical analysis shows different behaviors for velocity, temperature, and concentration based on parameters such as Grashof number and thermophoresis.
Article
Thermodynamics
Shuguang Li, M. Ijaz Khan, Faris Alzahrani, Sayed M. Eldin
Summary: The objective of this study is to analyze the unsteady flow of a viscous liquid under the influence of an induced magnetic field and controlled by uniform suction. The thermal equation is considered with dissipations, Ohmic heating, radiation, and entropy rate in a thermodynamical system. The focus is on the analysis of thermal transformation and entropy production. Nonlinear differential systems are obtained and solved numerically using finite difference technique. The effects of magnetic field, entropy rate, concentration, and velocity on the relevant variables are addressed. The results show that an increase in suction variable leads to an increase in induced magnetic field, while the impact on velocity and thermal fields is opposite. The computational outcomes indicate that a higher magnetic Prandtl number amplifies the induced magnetic and thermal fields, and higher approximation of suction variable reduces the thermal field and concentration. A high entropy rate is found for larger magnetic Prandtl numbers, and larger radiation correspond to amplified temperature.
CASE STUDIES IN THERMAL ENGINEERING
(2023)
Article
Mathematics, Applied
Haiyan Jiang, Tiao Lu, Weitong Zhang
Summary: This paper proposes a new hybrid algorithm for the time-dependent Wigner equation, which is simple in structure yet highly efficient. Numerical experiments validate its reliability and efficiency in simulating quantum effects.
JOURNAL OF COMPUTATIONAL AND APPLIED MATHEMATICS
(2022)
Article
Optics
Xiaofeng Xu, Xiao-Qing Luo, Jingzhao Zhang, Weihua Zhu, Zhiyong Chen, Tie-Fu Li, W. M. Liu, Xin-Lin Wang
Summary: This study investigates the application of near-infrared plasmonic DFRs in a hybrid metasurface through numerical and theoretical approaches. The research demonstrates that plasmonic sensing can be achieved by modulating the polarization orientation and geometric parameters of the unit cells, resulting in resonance mode-broadening and mode-shifting. Additionally, the study shows the realization of a high ON/OFF ratio plasmonic switch and digital metasurface with plasmonic DFRs. These findings are significant for polarization-sensitive optical sensing, passive optical switches, and programmable metasurface devices.
Article
Computer Science, Interdisciplinary Applications
Akbar Zaman, Ambreen Afsar Khan
Summary: This letter investigates the simultaneous effects of non-Newtonian and curvature on unsteady nano-fluid flow through overlapping stenosed channel. A mathematical formulation is developed to analyze the influence of blood shear thinning/thickening effects on the rheology of the nano-fluid within curved channel. Numerical solutions for temperature, velocity and concentration equations are obtained to discuss hemodynamic effects due to the curvature of the stenosed channel.
MATHEMATICS AND COMPUTERS IN SIMULATION
(2021)
Article
Astronomy & Astrophysics
A. Breev, S. P. Gavrilov, D. M. Gitman, A. A. Shishmarev
Summary: This paper introduces a new exactly solvable case in strong-field quantum electrodynamics with a time-dependent external electric field, solving the Dirac equation to calculate the characteristics of the corresponding vacuum instability. The study compares the effects of rapidly and slowly changing analytic asymmetric electric fields, as well as compares exact results with approximations proposed by the authors earlier, demonstrating the effectiveness of such approximations.
Article
Mathematics
Tom Cuchta, Robert J. Niichel
Summary: The classical memoryless property induces the geometric distribution for discrete random variables and the exponential distribution for continuous random variables. However, when the range of the random variable is an arbitrary closed subset of the real line, interpreting the memoryless property becomes challenging. We explore multiple proposals and their consequences, specifically whether a given definition of memoryless will result in a specific distribution.
MATHEMATICA SLOVACA
(2023)
Article
Mathematics, Applied
Yinlong Jing, Can Li
Summary: In this paper, a block-centered finite difference method with two kinds of tempered Θ1 discretizations is presented for a tempered subdiffusion model. The numerical schemes approximate the tempered Caputo fractional derivative in the temporal direction using implicit tempered Θ1 discretization and implicit-explicit tempered Θ1 discretization, and approximate derivatives in the spatial direction using the block-centered finite difference method. The stability and convergence of the schemes are proven for non-uniform grids in one- and two-dimensional problems, and extensive numerical examples are provided to validate the theoretical results.
COMPUTERS & MATHEMATICS WITH APPLICATIONS
(2023)
Article
Astronomy & Astrophysics
Emily I. Mason, Roberto Lionello, Cooper Downs, Jon A. Linker, Ronald M. Caplan, Marc L. Derosa
Summary: This Letter presents the first global comparison between traditional steady-state magnetohydrodynamic models and a new, fully time-dependent thermodynamic magnetohydrodynamic simulation of the global corona. The results show that the time-dependent model produces a qualitatively different corona with higher magnetic energy levels and more pronounced evolution of coronal holes along the following edge.
ASTROPHYSICAL JOURNAL LETTERS
(2023)
Article
Computer Science, Interdisciplinary Applications
Reza Doostaki, Mohammad Mehdi Hosseini, Abbas Salemi
Summary: This paper presents a new compact finite difference scheme for solving linear high-dimensional time-dependent partial differential equations (PDEs). The proposed method achieves arbitrary order accuracy in both time and space, and obtains the approximation of partial derivatives simultaneously at all grid points. The numerical results demonstrate the accuracy and efficiency of the proposed method by solving parabolic and convection-diffusion equations with fourth, sixth, and eighth-order simultaneously compact finite difference schemes.
MATHEMATICS AND COMPUTERS IN SIMULATION
(2023)