Xia Ji
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View article: Classification Framework of Introduced Crabapple (Malus spp.) Cultivars Based on Morphological and Numerical Traits: Insights for Germplasm Conservation and Landscape Forestry
Classification Framework of Introduced Crabapple (Malus spp.) Cultivars Based on Morphological and Numerical Traits: Insights for Germplasm Conservation and Landscape Forestry Open
Crabapples (Malus spp.) are widely planted ornamental and multipurpose trees in temperate regions and represent an important component of forest and landscape resources. However, the absence of a standardized classification framework has l…
View article: Student Characteristics and ICT Usage as Predictors of Computational Thinking: An Explainable AI Approach
Student Characteristics and ICT Usage as Predictors of Computational Thinking: An Explainable AI Approach Open
Computational thinking (CT) is recognized as a core competency for the 21st century, and its development is shaped by multiple factors, including students’ individual characteristics and their use of information and communication technolog…
View article: A Method for Estimating the Direction of Arrival of Waves Across the Ice Layer Based on Wavenumber Asymptotic
A Method for Estimating the Direction of Arrival of Waves Across the Ice Layer Based on Wavenumber Asymptotic Open
In addressing the problem of direction estimation for underwater targets across the ice layer, this paper starts from the propagation theory of simple harmonic waves beneath the ice layer. It theoretically deduces and analyzes the impact o…
View article: Research on the distribution structure of 2D piston electro-hydraulic pump based on fluid-structure interaction
Research on the distribution structure of 2D piston electro-hydraulic pump based on fluid-structure interaction Open
To address the drawbacks of traditional hydraulic power units, we embedded a 2D piston pump inside the motor rotor, proposing a 2D piston electro-hydraulic pump. The space cam mechanism serves as the primary force-bearing structure during …
View article: Composite phase modulated beam steering controllable reflective metasurface
Composite phase modulated beam steering controllable reflective metasurface Open
Terahertz metasurface functional devices as an effective method to control terahertz waves have attracted extensive attention from researchers. In order to enhance the functionality and flexibility of the metasurface and adapt to diverse a…
View article: Mechanisms of Heat-Treatment-Induced Cracking in Additively Manufactured IN738 Alloy
Mechanisms of Heat-Treatment-Induced Cracking in Additively Manufactured IN738 Alloy Open
The present study conducts a comprehensive study on heat-treatment-induced cracking of Inconel 738 (IN738) alloy fabricated by laser powder bed fusion (LPBF) using scanning electron microscopy (SEM), energy dispersion spectrum (EDS), and e…
View article: Error estimation to the direct sampling method for the inverse acoustic source problem with multi-frequency data
Error estimation to the direct sampling method for the inverse acoustic source problem with multi-frequency data Open
In this article, we introduce a novel direct sampling indicator function for solving the inverse source problem (ISP) associated with the Helmholtz equation. The proposed method is rigorously evaluated through numerical analysis of both si…
View article: Toroidal modeling of plasma flow damping and density pump-out by RMP during ELM mitigation in HL-2A
Toroidal modeling of plasma flow damping and density pump-out by RMP during ELM mitigation in HL-2A Open
Reduction of both the plasma density and toroidal flow speed, due to application of the predominantly n = 1 ( n is the toroidal mode number) resonant magnetic perturbation (RMP) for controlling the edge localized mode in the HL-2A tokamak,…
View article: In-situ control of residual stress and its distribution in a titanium alloy additively manufactured by laser powder bed fusion
In-situ control of residual stress and its distribution in a titanium alloy additively manufactured by laser powder bed fusion Open
Remarkable residual stress is commonly present in metal components produced by laser additive manufacturing due to the inherent rapid heating/cooling rate and high temperature gradient. This is especially true in the laser powder bed fusio…
View article: MHD instability dynamics and turbulence enhancement towards the plasma disruption at the HL-2A tokamak
MHD instability dynamics and turbulence enhancement towards the plasma disruption at the HL-2A tokamak Open
The evolutions of MHD instability behaviors and enhancement of both electrostatic and electromagnetic turbulence towards the plasma disruption have been clearly observed in the HL-2A plasmas. Two types of plasma disruptive discharges have …
View article: Effect of Particle Size Distribution on the Printing Quality and Tensile Properties of Ti-6Al-4V Alloy Produced by LPBF Process
Effect of Particle Size Distribution on the Printing Quality and Tensile Properties of Ti-6Al-4V Alloy Produced by LPBF Process Open
The efficiency of the fabrication and the cost of feedstock materials are important constraining factors for a wider application of the laser powder bed fusion (LPBF) process in the industry. Therefore, it is necessary to investigate the f…
View article: The effect of impurity seeding into the closed divertor on plasma detachment in the HL-2A tokamak
The effect of impurity seeding into the closed divertor on plasma detachment in the HL-2A tokamak Open
Recent progress towards an increased understanding of detached divertor physics has been made with the highly closed divertor geometry in HL-2A. Non-intrinsic impurities were injected into the outer divertor chamber, and increased divertor…
View article: “Trees Don’t Sing! … Eagle Feather Has no Power!”—Be Wary of the Potential Numbing Effects of School Science
“Trees Don’t Sing! … Eagle Feather Has no Power!”—Be Wary of the Potential Numbing Effects of School Science Open
Educational philosopher Maxine Greene called for the “centrality of the arts” to education at all levels decades ago, yet the aesthetic core of education has been often negated to the margin or completely forgotten in public education. Wha…
View article: A simple low-degree optimal finite element scheme for the elastic transmission eigenvalue problem
A simple low-degree optimal finite element scheme for the elastic transmission eigenvalue problem Open
The paper presents a finite element scheme for the elastic transmission eigenvalue problem written as a fourth order eigenvalue problem. The scheme uses piecewise cubic polynomials and obtains optimal convergence rate. Compared with other …
View article: Lowest-degree piecewise polynomial de Rham complex on general quadrilateral grids
Lowest-degree piecewise polynomial de Rham complex on general quadrilateral grids Open
This paper is devoted to the construction of finite elements on grids that consist of general quadrilaterals not limited in parallelograms. Two finite elements defined as Ciarlet's triple are established for the $H^1$ and $H(\rm rot)$ elli…
View article: Lowest-degree polynomial de Rham complex on general quadrilateral grids
Lowest-degree polynomial de Rham complex on general quadrilateral grids Open
This paper devotes to the construction of finite elements on grids that consist of general quadrilaterals not limited in parallelograms. Two finite elements are established for the $H^1$ and $H(\rm rot)$ elliptic problems, respectively. Th…
View article: Identification of point like objects with multi-frequency sparse data
Identification of point like objects with multi-frequency sparse data Open
The inverse acoustic scattering of point objects using multi-frequency sparse measurements are studied. The objects may be a sum of point sources or point like scatterers. We show that the locations and scattering strengths of the point ob…
View article: Inverse electromagnetic obstacle scattering problems with multi-frequency sparse backscattering far field data
Inverse electromagnetic obstacle scattering problems with multi-frequency sparse backscattering far field data Open
This paper is dedicated to design a direct sampling method of inverse electromagnetic scattering problems, which uses multi-frequency sparse backscattering far field data for reconstructing the boundary of perfectly conducting obstacles. W…
View article: A high accuracy nonconforming finite element scheme for Helmholtz transmission eigenvalue problem
A high accuracy nonconforming finite element scheme for Helmholtz transmission eigenvalue problem Open
In this paper, we consider a cubic $H^2$ nonconforming finite element scheme $B_{h0}^3$ which does not correspond to a locally defined finite element with Ciarlet$'$s triple but admit a set of local basis functions. For the first time, we …
View article: Inverse electromagnetic source scattering problems with multi-frequency sparse phased and phaseless far field data
Inverse electromagnetic source scattering problems with multi-frequency sparse phased and phaseless far field data Open
This paper is concerned with uniqueness, phase retrieval and shape reconstruction methods for solving inverse electromagnetic source scattering problems with multi-frequency sparse phased or phaseless far field data. With the phased data, …
View article: Inverse acoustic scattering problems with multi-frequency sparse backscattering far field data
Inverse acoustic scattering problems with multi-frequency sparse backscattering far field data Open
The inverse acoustic scattering problems using multi-frequency backscattering far field patterns at isolated directions are studied. The underlying object could be point like scatterers, small scatterers, extended inhomogeneities and obsta…
View article: A lowest order mixed finite element method for the elastic transmission eigenvalue problem
A lowest order mixed finite element method for the elastic transmission eigenvalue problem Open
The goal of this paper is to develop numerical methods computing a few smallest elastic interior transmission eigenvalues, which are of practical importance in inverse elastic scattering theory. The problem is challenging since it is nonli…
View article: Influence of resonant magnetic perturbations and induced islands on plasma rotations and turbulence properties in the J-TEXT tokamak
Influence of resonant magnetic perturbations and induced islands on plasma rotations and turbulence properties in the J-TEXT tokamak Open
Dedicated experiments have been carried out at the J-TEXT tokamak for investigating plasma responses to the externally applied resonant magnetic perturbation (RMP) field with various RMP currents under four different toroidal phases. After…
View article: Phaseless inverse source scattering problem: phase retrieval, uniqueness and direct sampling methods
Phaseless inverse source scattering problem: phase retrieval, uniqueness and direct sampling methods Open
Similar to the obstacle or medium scattering problems, an important property of the phaseless far field patterns for source scattering problems is the translation invariance. Thus it is impossible to reconstruct the location of the underly…
View article: Target reconstruction with a reference point scatterer using phaseless far field patterns
Target reconstruction with a reference point scatterer using phaseless far field patterns Open
An important property of the phaseless far field patterns with incident plane waves is the translation invariance. Thus it is impossible to reconstruct the location of the underlying scatterers. By adding a reference point scatterer into t…
View article: Computation of Transmission Eigenvalues for Elastic Waves
Computation of Transmission Eigenvalues for Elastic Waves Open
The goal of this paper is to develop numerical methods computing a few smallest elasticity transmission eigenvalues, which are of practical importance in inverse scattering theory. The problem is challenging since it is nonlinear, non-self…
View article: A Multi-level Mixed Element scheme of the two dimensional helmholtz transmission eigenvalue problem
A Multi-level Mixed Element scheme of the two dimensional helmholtz transmission eigenvalue problem Open
In this paper, we present a multi-level mixed element scheme for the Helmholtz transmission eigenvalue problem on polygonal domains that are not necessarily able to be covered by rectangle grids. We first construct an equivalent linear mix…