期刊：
Mathematical Methods in the Applied Sciences,2025年48(5):5768-5780 ISSN：0170-4214
通讯作者：
Chen, HW
作者机构：
[Chen, Huiwen; Ouyang, Zigen; Xu, Xiaoliang] Univ South China, Sch Math & Phys, Hengyang, Hunan, Peoples R China.;[Chen, Huiwen; Ouyang, Zigen] Univ South China, Hunan Key Lab Math Modeling & Sci Comp, Hengyang, Hunan, Peoples R China.
通讯机构：
[Chen, HW ] U;Univ South China, Sch Math & Phys, Hengyang, Hunan, Peoples R China.;Univ South China, Hunan Key Lab Math Modeling & Sci Comp, Hengyang, Hunan, Peoples R China.
关键词：
critical point theory;existence and multiplicity;ground state solution;local superlinear condition;periodic discrete nonlinear Schr & ouml;dinger equation
摘要：
Consider the nonlinear difference equations of the form & Laplacetrf;u=fm(u),m is an element of & Zopf;$$ \mathit{\mathcal{L}u}={f}_m(u),\kern0.3em m\in \mathbb{Z} $$, where & Laplacetrf;$$ \mathcal{L} $$ is a Jacobi operator given by & Laplacetrf;um=amum+1+am-1um-1+bmum$$ \mathcal{L}{u}_m={a}_m{u}_{m+1}+{a}_{m-1}{u}_{m-1}+{b}_m{u}_m $$ for m is an element of & Zopf;,am$$ m\in \mathbb{Z},\kern0.3em \left\{{a}_m\right\} $$ and bm$$ \left\{{b}_m\right\} $$ are real valued T$$ T $$-periodic sequences, and f:& Zopf;x & Ropf;->& Ropf;$$ f:\mathbb{Z}\times \mathbb{R}\to \mathbb{R} $$. Applying critical point theory and a new analytical method, we obtain that the above problem has ground state solutions and infinitely many geometrically distinct solutions under the local superlinear condition limx ->infinity integral 0xfm(t)dt|x|2=infinity$$ {\lim}_{verbarxverbar\to \infty}\frac{\int_0<^>x{f}_m(t) dt}{{\left|x\right|}<^>2}=\infty $$ uniformly in m is an element of D$$ m\in D $$ for some set D subset of & Zopf;$$ D\subset \mathbb{Z} $$ instead of the global superlinear condition limx ->infinity integral 0xfm(t)dt|x|2=infinity$$ {\lim}_{verbarxverbar\to \infty}\frac{\int_0<^>x{f}_m(t) dt}{{\left|x\right|}<^>2}=\infty $$ uniformly in m is an element of & Zopf;$$ m\in \mathbb{Z} $$.
作者机构：
[Yan, Xuejin; Yan, XJ] Univ South China, Sch Civil Engn, Hengyang 421001, Hunan, Peoples R China.;[Xu, Feng; Xu, F; Guo, Changqing] Univ South China, Sch Math & Phys, Hengyang 421001, Hunan, Peoples R China.
通讯机构：
[Yan, XJ ; Xu, F; Guo, CQ ] U;Univ South China, Sch Civil Engn, Hengyang 421001, Hunan, Peoples R China.;Univ South China, Sch Math & Phys, Hengyang 421001, Hunan, Peoples R China.
关键词：
fluid-conveying pipe;base excitation;impact vibration response;Pasternak base
摘要：
When the fluid-conveying pipe is buried on the surface of the base, it will not only suffer from rigid impact damage caused by base excitation and surrounding gravel, but also be affected by the characteristics of the base, which makes safety accidents extremely likely to occur during the operation of the fluid-conveying pipe. Based on the Hamilton principle, a mathematical model of simply supported fluid-conveying pipe structures with a rigid constraint on the Pasternak base under base excitation is established. The Galerkin method is used to discretize the equation of motion, and the NDFS algorithm is employed to solve the system of equations. The influence is discussed in terms of the base excitation frequency, internal flow rate, and the viscoelastic coefficient of the pipe on the model. Bifurcation diagrams, phase diagrams, Poincaré maps, and time-history curves under various parameters are used to analyze the impact vibration response of the fluid-conveying pipe system. The research shows that: grazing impact usually occurs when the system’s motion state changes under impact vibration, and at a lower base excitation frequency, grazing impact will induce incomplete chatter-impact vibration in the system; there is a particular dynamic law in the evolution between quasi-periodic motion and single-period non-impact vibration on the Poincaré map; the increase in the equivalent linear spring stiffness K and shear stiffness KG of the Pasternak base is beneficial for resisting the unstable factors caused by base excitation. The findings of this study provide theoretical support for the optimal design, operation maintenance, and safety assurance of fluid-conveying pipes on the Pasternak base.
摘要：
Cu-based self-lubricating composites have excellent mechanical properties and enhanced friction characteristics, rendering them ideal for aerospace wear parts. However, the significant mismatch in coefficients of thermal expansion (CTE) between them and counterparts, typically steel, would limit their widespread application. To address this issue, Ni50Fe powders with a low CTE are incorporated into Cu15Ni8Sn-MoS 2 composites via mixing and hot-pressed sintering, resulting in Cu15Ni8Sn-Ni50Fe-MoS 2 composites. The addition of Ni50Fe significantly reduces the CTE of the composites. When added in moderation, Ni50Fe can enhance the mechanical properties and wear resistance, despite a slight degradation in lubricity. The variations in mechanical and friction properties of the composites are attributed to the reaction of Cu and Fe with MoS 2 and the change of matrix composition. The composite containing 40 vol% Ni50Fe (N40) has the best comprehensive performance. Compared to the Cu15Ni8Sn-MoS 2 composite, the CTE of N40 is reduced by 13.7%, along with increases in hardness (5.2%), transverse rupture strength (19.1%), radial crushing strength (11.3%), and a reduction in wear rate (8.8%), although its friction coefficient increases by 15.4%.
作者机构：
[Qian, Shengyou; Zou, Xiao; Chang, Shuai; Ju, Fangfang; Gong, Jinru; Tian, Feng; Lei, Weirui; Qian, SY] Hunan Normal Univ, Sch Phys & Elect, Changsha 410081, Peoples R China.;[Hu, Jiwen] Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.;[Zhai, Jintao] Hunan Univ, Coll Comp Sci & Elect Engn, Changsha 410012, Peoples R China.
通讯机构：
[Zou, X; Ju, FF; Qian, SY ] H;Hunan Normal Univ, Sch Phys & Elect, Changsha 410081, Peoples R China.
关键词：
AP;Flow and heat transfer;Focused ultrasound;Porous media
摘要：
Focused ultrasound has been widely used for the thermotherapy of soft tissue lesions. In this process, non-Fourier heat conduction and porous medium theory has to be considered because of non-homogeneous media. The study estimates the effects of the temperature lag and porous medium on the plaque ablation and drug treatment by focused ultrasound (FU). This study integrated TWMBT with the porous media heat transfer equation to characterize the internal temperature distribution within atherosclerotic plaque (AP) during FU application. The coupling equations are solved with finite element method. This paper focuses on the effects of porosity, permeability, and attenuation coefficient on the temperature and flow rate within the AP. The results consider artery wall thickness on heating of AP by FU. In addition, this study qualitatively analyzed the differences among the Pennes, TWMBT, and porous media heat conduction equations. The results show that the temperature responses of biological tissues exhibits lagging behaviors, which are inherently related to the physical time scale. Because of the disparities in the physical characteristics of the target and surrounding tissues, fluid flow within AP can have an impact on the distribution of tissue temperature, the direction of flow between solid tissues is determined by the permeability coefficient and ultrasonic intensity. The permeability coefficient, frequency and attenuation coefficient have a significant effect on the fluid flow within AP. Both heat dissipation and heat convergence are characteristics of fluid flow within the tissue, the focal location and the physical property parameters may affect the fluid heat dissipation and heat collection properties within the tissue. Furthermore, the temperature peak may not occur at the focus. The model can provide an analytical template for different types of precise thermal ablation AP, including radiofrequency ablation, microwave therapy, and laser ablation besides FU ablation, and can also provide a case for adjunctive drug transport.
Focused ultrasound has been widely used for the thermotherapy of soft tissue lesions. In this process, non-Fourier heat conduction and porous medium theory has to be considered because of non-homogeneous media. The study estimates the effects of the temperature lag and porous medium on the plaque ablation and drug treatment by focused ultrasound (FU). This study integrated TWMBT with the porous media heat transfer equation to characterize the internal temperature distribution within atherosclerotic plaque (AP) during FU application. The coupling equations are solved with finite element method. This paper focuses on the effects of porosity, permeability, and attenuation coefficient on the temperature and flow rate within the AP. The results consider artery wall thickness on heating of AP by FU. In addition, this study qualitatively analyzed the differences among the Pennes, TWMBT, and porous media heat conduction equations. The results show that the temperature responses of biological tissues exhibits lagging behaviors, which are inherently related to the physical time scale. Because of the disparities in the physical characteristics of the target and surrounding tissues, fluid flow within AP can have an impact on the distribution of tissue temperature, the direction of flow between solid tissues is determined by the permeability coefficient and ultrasonic intensity. The permeability coefficient, frequency and attenuation coefficient have a significant effect on the fluid flow within AP. Both heat dissipation and heat convergence are characteristics of fluid flow within the tissue, the focal location and the physical property parameters may affect the fluid heat dissipation and heat collection properties within the tissue. Furthermore, the temperature peak may not occur at the focus. The model can provide an analytical template for different types of precise thermal ablation AP, including radiofrequency ablation, microwave therapy, and laser ablation besides FU ablation, and can also provide a case for adjunctive drug transport.
作者机构：
[Lin, Wenbin; Jiang, Chunhua; Yang, Bo; Lin, WB] Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.;[Yang, Bo] Chinese Acad Sci, Purple Mt Observ, Nanjing 210023, Peoples R China.
通讯机构：
[Lin, WB ] U;Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.
关键词：
Black holes;Regular Simpson-Visser black-bounce spacetime;Periastron advance
摘要：
In this paper, we present the second post-Newtonian solution for the quasi-Keplerian motion of a test particle in the regular Simpson-Visser black-bounce spacetime which has a bounce parameter $a$. The obtained solution is formulated in terms of the orbital energy, angular momentum, and the bounce parameter of the black hole. We explicitly analyze the leading effects of the bounce parameter, which has dimensions of length, on the test particle's orbit, including the periastron advance and orbital period. Then, we apply this model to the precessing motion of OJ 287 and determine the upper limits of the dimensionless bounce parameter as $a/m =3.45\pm 0.01$, where $m$ is the mass of the regular black hole. Compared with the bound given by the periastron advance of star S2, our bound on $a/m$ is reduced by one order of magnitude, although our upper limit of $a$ still needs further improvement.
作者机构：
[Lin, Wenbin; Lin, WB] Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.;[Lin, Wenbin; Lin, WB] Southwest Jiaotong Univ, Sch Phys Sci & Technol, Chengdu 610031, Peoples R China.
通讯机构：
[Lin, WB ] U;Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.;Southwest Jiaotong Univ, Sch Phys Sci & Technol, Chengdu 610031, Peoples R China.
关键词：
post-Newtonian approximation;gravitomagnetic field;second gravitational potential;spherically-symmetric system
摘要：
We prove that the post-Newtonian time-dependent metric of the self-gravitating and collapsing infinitely-thin spherical shell does satisfy Einstein field equations to the corresponding order. Meanwhile, the leading-order components of the thin spherical shell's energy-momentum tensor are recovered.
期刊：
Nuclear Engineering and Design,2025年433:113872 ISSN：0029-5493
通讯作者：
Liu, HL
作者机构：
[Liu, Hongliang; Ouyang, Zigen; Liu, HL; Liu, Wangheng] Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.;[Zeng, Wenjie] Univ South China, Sch Nucl Sci & Technol, Hengyang 421001, Peoples R China.;[Liu, Hua] Univ South China, Sch Elect Engn, Hengyang 421001, Peoples R China.
通讯机构：
[Liu, HL ] U;Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.
关键词：
Adaptive learning observer;Radial basis function neural networks;Fixed-time fault-tolerant control;Control rod drive mechanism faults;Load following for modular high-temperature;gas-cooled reactor
摘要：
Load following of the Modular High-Temperature Gas-Cooled Reactor (MHTGR) under Control Rod Drive Mechanism (CRDM) faults and disturbances remains a major challenge. This paper focuses on proposing a fixed-time fault-tolerant control method for this issue without considering the sensitivities associated with parameter setting. Firstly, to reconstruct some unmeasurable states of the MHTGR and the values of CRDM faults, an adaptive learning observer is established. Based on the learning characteristic of Radial Basis Function Neural Networks (RBFNN), the lumped uncertainties can be approximated. And then a fixed-time fault-tolerant controller is developed to ensure that the actual load output of the MHTGR actually tracks the expected output power within a fixed time, which can be determined through the system and controller parameters. Finally, simulations under two operational conditions demonstrate the control method is effective and feasible to the MHTGR system under disturbance and CRDM faults.
Load following of the Modular High-Temperature Gas-Cooled Reactor (MHTGR) under Control Rod Drive Mechanism (CRDM) faults and disturbances remains a major challenge. This paper focuses on proposing a fixed-time fault-tolerant control method for this issue without considering the sensitivities associated with parameter setting. Firstly, to reconstruct some unmeasurable states of the MHTGR and the values of CRDM faults, an adaptive learning observer is established. Based on the learning characteristic of Radial Basis Function Neural Networks (RBFNN), the lumped uncertainties can be approximated. And then a fixed-time fault-tolerant controller is developed to ensure that the actual load output of the MHTGR actually tracks the expected output power within a fixed time, which can be determined through the system and controller parameters. Finally, simulations under two operational conditions demonstrate the control method is effective and feasible to the MHTGR system under disturbance and CRDM faults.
摘要：
This paper presents a Respiratory Syncytial Virus (RSV) epidemic model for a continuous human population of super-spreading infected individuals. The model uses a generalized fractal-fractional derivative with the Mittag-Leffler function to analyze transmission, considering different infection stages, and demonstrates the effectiveness of certain individuals as viral spreaders. Using linear growth and Lipschitz requirements, the study determines the existence, uniqueness, positiveness, and boundedness of a proposed fractional-order system in order to assess its viability. The global stability of equilibrium points is verified by the Lyapunov function, and the effects of the model's parameters are investigated through sensitivity analysis. To comprehend the model's behavior and create preventative measures for infected people, a numerical simulation of its activity is also carried out. By offering a more realistic depiction of virus behavior at various dimensions and population effects, the fractal-fractional model enhances comprehension and forecasts. The results highlight the importance of fractional order and its fitting function in the model by demonstrating how input parameters affect the dynamic behavior of RSV infection. Such an investigation will aid in understanding the behavior of the RSV and develop prevention measures for infected individuals.
摘要：
In this paper, we give six classes of permutation polynomials of the form $ (x^{2^m}+x+\delta)^s+ax $ over $ \mathbb{F}_{2^{2m}} $ and six classes of permutation polynomials of the form $ (x^{p^m}-x+\delta)^s+ax^{p^m}+a^{p^m}x $ over $ \mathbb{F}_{p^{2m}} $ ($ p $ being an odd prime), respectively. In addition, we also investigate permutation polynomials obtained from piecewise functions. Consequently, we find some complete permutation polynomials.
期刊：
ELECTRONIC JOURNAL OF DIFFERENTIAL EQUATIONS,2025年2025(64) ISSN：1072-6691
通讯作者：
Liu, HL
作者机构：
[Zhou, Yao; Liu, Hongliang; Liu, HL] Univ South China, Sch Math & Phys, Hengyang 421001, Hunan, Peoples R China.
通讯机构：
[Liu, HL ] U;Univ South China, Sch Math & Phys, Hengyang 421001, Hunan, Peoples R China.
关键词：
Singular perturbed;second order delay lattice system;uniform attractor;upper semicontinuity;continuous process;almost periodic function
摘要：
. In this article, we consider the upper semicontinuity of the uniform attractors for the singular perturbed second order nonautonomous delay lattice systems driven by the almost periodic forces as the coefficient of second order derivative term tends to zero under the Hausdorff semidistance. First we prove the existence of uniform attractors for the second order and the corresponding first order nonautonomous delay lattice systems. Then we establish some prior uniform estimations of solutions. Finally we study the upper semicontinuity of the uniform attractors as the coefficient of second order derivative term tends to zero which showing the relationship between the uniform attractors for second order and the corresponding first order nonautonomous delay lattice systems.
作者机构：
[Fan, Chenzhou; Wang, Tianlin] Univ South China, Sch Civil Engn, Hengyang 421001, Peoples R China.;[Xu, Feng; Xu, F; Guo, Changqing] Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.
通讯机构：
[Xu, F ] U;Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.
关键词：
Foundation excitation;Gap constraint;Fluid-conveying pipe;Impact vibration
摘要：
In practical engineering, the unilateral gap constraint impact vibration in fluid-conveying pipes is a critical concern, often arising from constraint loosening or the presence of barriers around the pipe. These factors can significantly affect the service life and safety reliability of the pipes. A tension and compression anisotropy spring with rapidly increasing restoring force in compression but almost zero restoring force in tension is proposed to simulate the unilateral gap constraint, model a fluid-conveying pipe with a Pfluger column. Its reliability is also verified based on the bifurcation phase diagram comparison between the small and large stiffness conditions. Subsequently, we establish a vibration mechanics analysis model for the cantilever fluid-conveying pipe under foundation excitation to assess the effects of basic excitation frequency, fluid velocity, distributed follower force, position coordinate of unilateral gap constraint, and the viscoelastic coefficient on the impact vibration stability of the fluid-conveying pipe. Our findings reveal that when the period-doubling bifurcation sequence is interrupted by Bare-grazing bifurcation, the system directly transitions into chaotic vibration or induces a new period-doubling bifurcation sequence, followed by re-entry into chaotic vibration. These results provide valuable insights into the intricate dynamics of fluid-conveying pipes under foundation excitation, offering a deeper understanding of the impact of various parameters on the pipe's vibration.
In practical engineering, the unilateral gap constraint impact vibration in fluid-conveying pipes is a critical concern, often arising from constraint loosening or the presence of barriers around the pipe. These factors can significantly affect the service life and safety reliability of the pipes. A tension and compression anisotropy spring with rapidly increasing restoring force in compression but almost zero restoring force in tension is proposed to simulate the unilateral gap constraint, model a fluid-conveying pipe with a Pfluger column. Its reliability is also verified based on the bifurcation phase diagram comparison between the small and large stiffness conditions. Subsequently, we establish a vibration mechanics analysis model for the cantilever fluid-conveying pipe under foundation excitation to assess the effects of basic excitation frequency, fluid velocity, distributed follower force, position coordinate of unilateral gap constraint, and the viscoelastic coefficient on the impact vibration stability of the fluid-conveying pipe. Our findings reveal that when the period-doubling bifurcation sequence is interrupted by Bare-grazing bifurcation, the system directly transitions into chaotic vibration or induces a new period-doubling bifurcation sequence, followed by re-entry into chaotic vibration. These results provide valuable insights into the intricate dynamics of fluid-conveying pipes under foundation excitation, offering a deeper understanding of the impact of various parameters on the pipe's vibration.
作者机构：
[Wang, Hongyong] Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.;[Ou, Chunhua; Ou, CH] Mem Univ Newfoundland, Dept Math & Stat, St John, NF A1C 5S7, Canada.
通讯机构：
[Ou, CH ] M;Mem Univ Newfoundland, Dept Math & Stat, St John, NF A1C 5S7, Canada.
关键词：
Lotka-Volterra competition system;gap formation;forced pulsating waves;spreading dynamics;shifting media
摘要：
We study the propagation dynamics of a Lotka-Volterra competition system in which one growth rate behaves like a monotonically decreasing wave profile that shifts with a given speed and is also periodic in the first spatial variable, while the other growth rate behaves similarly, except that its profile is monotonically increasing with respect to the shifting variable. Furthermore, both growth functions are assumed to be sign-changed, which implies that the environments in which the species live switch spatially from 'good' regions (suitable for survival) to 'bad' regions (not suitable for survival) and vice versa. We reveal that the model admits a forced pulsating wave only when the forced speed lies within a finite interval (c & lowast;,c(& lowast;)) that contains zero. Biologically, this corresponds to the formation of a shifting cline. Moreover, we find that c(& lowast;)<0 and c(& lowast;)>0 can be calculated in terms of the Fisher-KPP speeds related to the linearized equations of each species. By applying a sliding technique, we show that the forced pulsating wave is unique. We also prove that the forced pulsating wave is Lyapunov-stable. Finally, the spreading dynamics of spatial gap formation in the two species are also investigated when the forced wave speed is either less than c(& lowast;) or greater that c(& lowast;). We employ a novel approach to demonstrate how the species invade in response to a shifting environment.
摘要：
The nonlinear vibrations developing in sheets and strips during rolling are of practical technological importance and of theoretical interest. However, the existing numerical methods adopted in research are plagued by problems such as computational inefficiency, difficulty in dealing with bifurcations, slow convergence and frequency cancellations. This study develops an analytical method for solving the problem of rolled strip quasi-periodic motions in the resonant state. First, the conventional incremental harmonic balance method is used to analyze the periodic response of a strip. Its nonlinear frequency response curve is obtained and the type of bifurcation along with its location is determined. Second, the quasi-periodic motion spectrum of the strip is characterized utilizing the fact that the adjacent frequencies in the side bands are equidistant from each other and contain two incommensurable fundamental frequencies. The fundamental frequencies of the strip quasi-periodic motion, as well as all of the frequency components and their corresponding amplitudes, are accurately resolved, especially the quasi-periodic motion response near the critical point. Finally, several numerical examples of the nonlinear vibrations exhibited by the rolled strip in the presence of internal resonance are investigated in depth to validate the proposed method performance and accuracy. These examples are concerned with the internal resonance with an even inherent frequency ratio of 1:6, which may arise during the rolling process, but remains relatively unexplored. The newly proposed method will add to the arsenal of available analytical techniques, expanding the capabilities of both researchers and practicing engineers.
作者机构：
[Ouyang, Yanquan; Tang, Xian; Lv, Ruimin] Univ South China, Sch Nucl Sci & Technol, Hengyang 421001, Peoples R China.;[Cheng, Jinjuan] Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.
通讯机构：
[Tang, X ] U;Univ South China, Sch Nucl Sci & Technol, Hengyang 421001, Peoples R China.
关键词：
Uranyl ions;NiAl-LDH/Sb;DFT;Adsorption
摘要：
In this work, the adsorption properties of uranyl ions (UO2) on the surfaces of two-dimensional metallic materials Sb, LDH, and NiAl-LDH/Sb are investigated using density functional theory (DFT). The computational results show that LDH/Sb has the best adsorption performance for UO2. The electronic structure, charge transfer, and electronic localization function analyses reveal that UO2 undergoes electronic orbital coupling with Ni and Sb of LDH/Sb and transfers the highest number of charges among the three substrates, which enables its stable adsorption. The dependence of adsorption rate on temperature was calculated, and it is concluded that the desorption temperature of uranyl ions on the surface of LDH/Sb is the highest at 570 K. The results indicate that NiAl-LDH/Sb is a good adsorbent material for uranyl ions and, therefore, has application prospects in uranium extraction from seawater.
作者机构：
[Chen, Guohao; Wang, Zhiqiao] Univ South China, Sch Civil Engn, Hengyang 421001, Peoples R China.;[Zhang, XY; Zhang, Xiaoyang] Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.
通讯机构：
[Zhang, XY ] U;Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.
关键词：
thermal effect;locally resonant;finite element method;tunable bandgap;defect states;waveguide
摘要：
Based on the finite element method, the modulation of the bending wave bandgap and bending waveguide of locally resonant phononic crystal (PnC) plates via a thermal environment is investigated. First, the finite element model of the PnC subjected to a thermal field is introduced; then, the modulation behavior of the bending wave bandgap of the PnC under thermal flux is illustrated; finally, the tunable waveguide of the bending waveguide of the PnC supercell is proposed to be realized by setting up a local heat source. The results show that the injected heat flux causes the PnC unit cell band structure to move toward the low-frequency region while the relative bandgap width increases. The linear defect state of the PnC supercell structure is realized by introducing a local heat source, and a new band is added to the bending wave bandgap of the original supercell. The transmission loss of the bending wave is significantly higher than that of the bending wave bandgap of the supercell in the frequency interval of the linear defect of the supercell, and the frequency response vibrational modes of the supercell structure validate the feasibility of the thermally controlled bending waveguide. This method provides a flexible and efficient control strategy for the frequency tuning of the bending wave bandgap and waveguide.
作者机构：
[Lin, Wenbin; Li, Jie] Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.;[Lv, Hongkui; Huang, Jiajun] Chinese Acad Sci, Inst High Energy Phys, Key Lab Particle Astrophys, Beijing 100049, Peoples R China.;[Lv, Hongkui] TIANFU Cosm Ray Res Ctr, Chengdu, Sichuan, Peoples R China.;[Lin, Wenbin; Liu, Yang] Univ South China, Sch Comp Sci, Hengyang 421001, Peoples R China.;[Huang, Jiajun] Univ Chinese Acad Sci, Beijing, Peoples R China.
通讯机构：
[Li, J ] U;Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.
摘要：
Abstract Identifying gamma rays and rejecting the background of cosmic-ray hadrons are crucial for very-high-energy gamma-ray observations and relevant scientific research. Based on the simulated data from the square kilometer array (KM2A) of LHAASO, eight high-level features were extracted for the gamma/hadron classification. Machine learning (ML) models, including logistic regression, support vector machines, decision trees, random forests, XGBoost, CatBoost, and deep neural networks (DNN) were constructed and trained using data sets of four energy bands ranging from 1012 to 1016 eV, and finally fused using the stacking ensemble algorithm. To comprehensively assess the classification ability of each model, the accuracy, F1 score, precision, recall, and area under the curve value of the receiver operating characteristic curve were used. The results show that the ML methods have a significant improvement on particle classification in LHAASO-KM2A, particularly in the low-energy range. Among these methods, XGBoost, CatBoost, and DNN demonstrate stronger classification capabilities than decision trees and random forests, while the fusion model exhibits the best discriminatory ability. The ML methods provide a useful and alternative method for gamma/hadron identification. The codes used in this paper are available at Zenodo at doi:10.5281/zenodo.13623261.
摘要：
Acoustic phonons have long been believed to dominate the lattice thermal conductivity ( κ l ) and the contribution of optical phonons can be neglected in crystal structures. KCaBi, as a high-throughput screening semiconductor with ultralow κ l [J. Am. Chem. Soc. 144, 4448 (2022)], has been demonstrated that the contribution of optical phonons plays an important role in thermal transport. In this work, by solving the Boltzmann transport equation, it is found that the κ l of KCaBi is 2.2 at 300K, with acoustic phonons dominating the z-direction κ l and optical phonons contributing around 50% to the x-direction κ l under the four-phonon picture. The uncommon contribution of optical phonons also manifests the possibility of tuning the κ l anisotropy based on optical phonons. Following this line of thinking, it is found that applying tensile strain can cause a more pronounced decrease of acoustic phonon contribution than that of optical counterpart due to the highly dispersive optical branches, thus enhancing the anisotropic ratio of κ l . Moreover, the microscopic mechanism is elucidated by analyzing the phonon dispersion relation, phonon mode-wise contribution and phonon scattering rates. Our study could provide appealing alternatives for the regulation of phonon transport from the viewpoint of optical phonons.
Acoustic phonons have long been believed to dominate the lattice thermal conductivity ( κ l ) and the contribution of optical phonons can be neglected in crystal structures. KCaBi, as a high-throughput screening semiconductor with ultralow κ l [J. Am. Chem. Soc. 144, 4448 (2022)], has been demonstrated that the contribution of optical phonons plays an important role in thermal transport. In this work, by solving the Boltzmann transport equation, it is found that the κ l of KCaBi is 2.2 at 300K, with acoustic phonons dominating the z-direction κ l and optical phonons contributing around 50% to the x-direction κ l under the four-phonon picture. The uncommon contribution of optical phonons also manifests the possibility of tuning the κ l anisotropy based on optical phonons. Following this line of thinking, it is found that applying tensile strain can cause a more pronounced decrease of acoustic phonon contribution than that of optical counterpart due to the highly dispersive optical branches, thus enhancing the anisotropic ratio of κ l . Moreover, the microscopic mechanism is elucidated by analyzing the phonon dispersion relation, phonon mode-wise contribution and phonon scattering rates. Our study could provide appealing alternatives for the regulation of phonon transport from the viewpoint of optical phonons.
摘要：
The problem of designing explicit bent and plateaued functions has been researched for several decades. However, finding new bent functions outside the well-known completed Maiorana-McFarland class $\mathcal {M}^{\#}$ is still a challenge. Plateaued functions have been characterized in many different ways, but there is no general and rigorous mathematical method to generate them directly, except for the ones in the spirit of the well-known Maiorana-McFarland constructions or those obtained through adaptations of the secondary constructions of bent functions. Jeong and Lee recently made significant advances regarding algorithms for constructing balanced plateaued functions with maximal algebraic degrees in [IEEE Trans. Inf. Theory, 70(2), 1408-1421, 2024]. Due to the gap between our significant interest in the notion of plateaued functions and the knowledge we have on it, our motivation is to bring further results on the constructions of plateaued functions that allow us to understand their structure better. This article creates a framework of new generic constructions of bent and plateaued functions by studying Boolean functions of the form $h(x)=f(x)+F(f_{1}(x),\ldots, f_{r}(x))$ , where $f_{i}(x)=f(x)+f(x+\mu _{i})$ for each $1\leq i\leq r$ . We firstly prove that h and f have the same extended Walsh-Hadamard spectrum if $D_{\mu _{i}}D_{\mu _{j}}f=0$ for any $1\leq i\lt j\leq r$ . This result extends a previous construction of bent functions to any Boolean functions. The strength of such a result is that it allows us to obtain several plateaued functions of high algebraic degrees from known ones with low algebraic degrees, which was a significant and challenging problem raised in the literature. Such a result is a real challenge and breaks a deadlock since no mathematical method allows the general constructions of plateaued functions. We next give an extended affine equivalent form of the function h, which provides us with another compelling perspective to design new bent functions (including those which are outside $\mathcal {M}^{\#}$ from certain known ones inside $\mathcal {M}^{\#}$ ) and plateaued functions. Finally, we present four generic constructions of bent functions outside $\mathcal {M}^{\#}$ from generalized Maiorana-McFarland functions.
摘要：
In the present work, based on Gamow-like model, considering the deformation effect of Coulomb po-
tential, where the effective nuclear constant is parameterized, we systematically investigate the cluster radioactivity half-lives of 25 trans-lead nuclei. For comparison, a universal
decay law (UDL) proposed by Qi et al. [Phys. Rev. C 80,044326 (2009)], a new semi-empirical formula for exotic
cluster decay proposed by M. Balasubramaniam et al. [Phys. Rev. C 70,017301 (2004)] and a scaling law proposed
by M. Horoi [J. Phys. G: Nucl. Part. Phys. 30,945 (2004)] are also used. The calculated results within deformed
Gamow-like model are in better agreement with the experimental half-lives. The deformation effect has also been
discussed within Gamow-like model as well as deforemed Gamow-like model. Moreover, we extend this model to
predict the cluster radioactivity half-lives of 49 nuclei whose decay energy are energetically allowed or observed but
not yet quantified in NUBASE2020.
