arXiv subjects

Qian Yi

Publications and source records attributed to Qian Yi.

5 recordsLinked to original sources

arXiv2025

A time-splitting Fourier pseudospectral method for the Wigner(-Poisson)-Fokker-Planck equations

In this article, we propose an efficient time-splitting Fourier pseudospectral method for the Wigner(-Poisson)-Fokker-Planck equations. The method achieves second-order accuracy in time and spectral accuracy in phase space, both of which are rigorously verified by numerical experiments. The validated scheme is then employed to study the long-time dynamics of these systems. We investigate the existence of steady states for both the Wigner-Fokker-Planck and Wigner-Poisson-Fokker-Planck equations. Notably, for the Wigner-Fokker-Planck system, our results provide numerical evidence for the existence of a steady state even when the external potential is far from harmonic. This is an important discovery, since this phenomenon has not been thoroughly established in theory.

math.NA↗

arXiv2025

Mathematical analysis and numerical simulation of coupled nonlinear space-fractional Ginzburg-Landau equations

The coupled nonlinear space fractional Ginzburg-Landau (CNLSFGL) equations with the fractional Laplacian have been widely used to model the dynamical processes in a fractal media with fractional dispersion. Due to the existence of fractional power derivatives and strong nonlinearity, it is extremely difficult to mathematically analyze the CNLSFGL equations and construct efficient numerical algorithms. For this reason, this paper aims to investigate the theoretical results about the considered system and construct a novel high-order numerical scheme for this coupled system. We prove rigorously an a priori estimate of the solution to the coupled system and the well-posedness of its weak solution. Then, to develop the efficient numerical algorithm, we construct a fourth-order numerical differential formula to approximate the fractional Laplacian. Based on this formula, we construct a high-order implicit difference scheme for the coupled system. Furthermore, the unique solvability and convergence of the established algorithm are proved in detail. To implement the implicit algorithm efficiently, an iterative algorithm is designed in the numerical simulation. Extensive numerical examples are reported to further demonstrate the correctness of the theoretical analysis and the efficiency of the proposed numerical algorithm.

math.NA↗

arXiv2020

Two-body charmed baryon decays involving decuplet baryon in the quark-diagram scheme

In the quark-diagram scheme, we study the charmed baryon decays of ${\bf B}_c\to {\bf B}^* M$, where ${\bf B}_c$ is $Λ_c^+$ or $Ξ_c^{+(0)}$, together with ${\bf B}^*$ ($M$) the decuplet baryon (pseudoscalar meson). It is found that only two $W$-exchange processes are allowed to contribute to ${\bf B}_c\to {\bf B}^* M$. Particularly, we predict ${\cal B}(Λ_c^+ \to Σ^{*0(+)} π^{+(0)})=(2.8\pm 0.4)\times 10^{-3}$, which respects the isospin symmetry. Besides, we take into account the $SU(3)$ flavor symmetry breaking, in order to explain the observation of ${\cal B}(Λ_c^+\to Σ^{*+}η)$. For the decays involving $Δ^{++}(uuu)$, we predict ${\cal B}(Λ_c^+\to Δ^{++} π^-,Ξ_c^+ \to Δ^{++} K^-) =(7.0\pm 1.4,13.5\pm 2.7)\times 10^{-4}$ as the largest branching fractions in the singly Cabibbo-suppressed $Λ_c^+,Ξ_c^+\to{\bf B}^*M$ decay channels, respectively, which are accessible to the LHCb, BELLEII and BESIII experiments.

hep-ph↗

arXiv2014

A High-Precision Multi-Channel TAC and QAC Module for the Neutron Detection Wall

A single width NIM module that includes eight channels TAC (time-to-amplitude converter) and QAC (charge-to-amplitude converter) is introduced in the paper, which is designed for the large neutron wall detector to measure charge (energy) and time interval simultaneously [1]. The module mainly adopts a high precision gated integral circuit to realize TAC and QAC. The input range of TAC is from 30 ns to 1 us, and the input range of QAC is from 40 pC to 600 pC. The linearity error of TAC is lower than 1.28 %, and the time resolution of TAC is less than 0.871 %. The linearity error of QAC is lower than 0.81 %, and the resolution of QAC is better than 0.936 %.

physics.ins-det↗

arXiv2013

Gamma Ray Array Detector Trigger Sub-System

Gamma Ray Array Detector (GRAD) is one of External Target Facility (ETF) subsystems at the Heavy Ion Research Facility at Lanzhou. The trigger subsystem of the GRAD has been developed based on Field Programmable Gate Array (FPGAs) and PXI interface. The GRAD trigger subsystem makes prompt L1 trigger decisions to select valid events. These decisions are made by processing the hit signals from 1024 CsI scintillators of the GRAD. According to the physical requirements, the GRAD trigger subsystem generates 12-bit trigger signals that are passed to the ETF global trigger system. In addition, the GRAD trigger subsystem generates trigger data that are packed and transmitted to the host computer via PXI bus for off-line analysis. The trigger processing is implemented in the front-end electronics and one FPGA of the trigger module. The logic of PXI transmission and reconfiguration is implemented in the other FPGA of the trigger module. The reliable and efficient performance in the Gamma-ray experiments demonstrates that the GRAD trigger subsystem is capable to satisfy the physical requirements.

physics.ins-det↗