This paper presents an analytical solution for the interaction of electric potentials, electric displacements, elastic deformations, and thermoelasticity, and describes electromagnetoelastic responses and perturbation...This paper presents an analytical solution for the interaction of electric potentials, electric displacements, elastic deformations, and thermoelasticity, and describes electromagnetoelastic responses and perturbation of the magnetic field vector in hollow structures （cylinder or sphere）, subjected to mechanical load and electric potential. The material properties, thermal expansion coefficient and magnetic permeability of the structure are assumed to be graded in the radial direction by a power law distribution. In the present model we consider the solution for the case of a hollow structure made of viscoelastic isotropic material, reinforced by elastic isotropic fibers, this material is considered as structurally anisotropic material. The exact solutions for stresses and perturbations of the magnetic field vector in FGM hollow structures are determined using the infinitesimal theory of magnetothermoelasticity, and then the hollow structure model with viscoelastic material is solved using the correspondence principle and Illyushin＇s approximation method. Finally, numerical results are carried out and discussed.展开更多
A new way of acoustic wave imaging was investigated. By using the Green function theory a system of integral equations,which linked wave number perturbation function with wave field, was firstly deduced. By taking var...A new way of acoustic wave imaging was investigated. By using the Green function theory a system of integral equations,which linked wave number perturbation function with wave field, was firstly deduced. By taking variation on these integral equations an inversion equation,which reflected the relation between the little variation of wave number perturbation function and that of scattering field, was further obtained. Finally, the perturbation functions of some identical targets were reconstructed, and some properties of the novel method including converging speed, inversion accuracy and the abilities to resist random noise and identify complex targets were discussed. Results of numerical simulation show that the method based on the variation principle has great theoretical and applicable value to quantitative nondestructive evaluation.展开更多
Using a first-principles approach based on density functional theory, this paper studies the electronic and dynamical properties of β-V2O5. A smaller band gap and much wider split-off bands have been observed in comp...Using a first-principles approach based on density functional theory, this paper studies the electronic and dynamical properties of β-V2O5. A smaller band gap and much wider split-off bands have been observed in comparison with α-V2O5. The Raman-and infrared-active modes at the F point of the Brillouin zone are evaluated with LO/TO splitting, where the symbol denotes the longitudinal and transverse optical model. The nonresonant Raman spectrum of a β-V2O5 powder sample is also computed, providing benchmark theoretical results for the assignment of the experimental spectrum. The computed spectrum agrees with the available experimental data very well. This calculation helps to gain a better understanding of the transition from α-to β-V2O5.展开更多
The geometric structure,electronic structure,and optical properties of CdHg（SCN）4 crystal are calculated by using the density functional perturbation theory and Green function screening Coulomb interaction approxima...The geometric structure,electronic structure,and optical properties of CdHg（SCN）4 crystal are calculated by using the density functional perturbation theory and Green function screening Coulomb interaction approximation.The band gap of CdHg（SCN）4 crystal is calculated to be 3.198 eV,which is in good agreement with the experimental value 3.265 eV.The calculated second-order nonlinear optical coefficients are d14 = 1.2906 pm/V and d15 = 5.0928 pm/V,which are in agreement with the experimental results（d14=（1.4 ±0.6） pm/V and d15=（6.0 ±0.9） pm/V）.Moreover,it is found that the contribution to the valence band mainly comes from Cd-4d,Hg-5d states,and the contributions to the valence band top and the conduction band bottom predominantly come from C-2p,N-2p,and S-3p states.The second-order nonlinear optical effect of CdHg（SCN）_4 crystal results mainly from the internal electronic transition of（SCN）^-.展开更多
The quantum hydrodynamic model for ion-acoustic waves in plasmas is studied.First,we design a new disturbance expansion to describe the ion fluid velocity and electric field potential.It should be emphasized that the ...The quantum hydrodynamic model for ion-acoustic waves in plasmas is studied.First,we design a new disturbance expansion to describe the ion fluid velocity and electric field potential.It should be emphasized that the piecewise function perturbation form is new with great difference from the previous perturbation.Then,based on the piecewise function perturbation,a(3+1)-dimensional generalized modified Korteweg–de Vries Zakharov–Kuznetsov(mKdV-ZK)equation is derived for the first time,which is an extended form of the classical mKdV equation and the ZK equation.The(3+1)-dimensional generalized time-space fractional mKdV-ZK equation is constructed using the semi-inverse method and the fractional variational principle.Obviously,it is more accurate to depict some complex plasma processes and phenomena.Further,the conservation laws of the generalized time-space fractional mKdV-ZK equation are discussed.Finally,using the multi-exponential function method,the non-resonant multiwave solutions are constructed,and the characteristics of ion-acoustic waves are well described.展开更多
Intrusion detection is critical to guaranteeing the safety of the data in the network.Even though,since Internet commerce has grown at a breakneck pace,network traffic kinds are rising daily,and network behavior chara...Intrusion detection is critical to guaranteeing the safety of the data in the network.Even though,since Internet commerce has grown at a breakneck pace,network traffic kinds are rising daily,and network behavior characteristics are becoming increasingly complicated,posing significant hurdles to intrusion detection.The challenges in terms of false positives,false negatives,low detection accuracy,high running time,adversarial attacks,uncertain attacks,etc.lead to insecure Intrusion Detection System(IDS).To offset the existing challenge,the work has developed a secure Data Mining Intrusion detection system(DataMIDS)framework using Functional Perturbation(FP)feature selection and Bengio Nesterov Momentum-based Tuned Generative Adversarial Network(BNM-tGAN)attack detection technique.The data mining-based framework provides shallow learning of features and emphasizes feature engineering as well as selection.Initially,the IDS data are analyzed for missing values based on the Marginal Likelihood Fisher Information Matrix technique(MLFIMT)that identifies the relationship among the missing values and attack classes.Based on the analysis,the missing values are classified as Missing Completely at Random(MCAR),Missing at random(MAR),Missing Not at Random(MNAR),and handled according to the types.Thereafter,categorical features are handled followed by feature scaling using Absolute Median Division based Robust Scalar(AMDRS)and the Handling of the imbalanced dataset.The selection of relevant features is initiated using FP that uses‘3’Feature Selection(FS)techniques i.e.,Inverse Chi Square based Flamingo Search(ICS-FSO)wrapper method,Hyperparameter Tuned Threshold based Decision Tree(HpTT-DT)embedded method,and Xavier Normal Distribution based Relief(XavND-Relief)filter method.Finally,the selected features are trained and tested for detecting attacks using BNM-tGAN.The Experimental analysis demonstrates that the introduced DataMIDS framework produces an accurate diagnosis about the attack with low computation time.The work avoids false alarm rate of attacks and remains to be relatively robust against malicious attacks as compared to existing methods.展开更多
The solution of water wave scattering problem involving small deformation on a porous bed in a channel, where the upper surface is bounded above by an infinitely extent rigid horizontal surface, is studied here within...The solution of water wave scattering problem involving small deformation on a porous bed in a channel, where the upper surface is bounded above by an infinitely extent rigid horizontal surface, is studied here within the framework of linearized water wave theory. In such a situation, there exists only one mode of waves propagating on the porous surface. A simplified perturbation analysis, involving a small parameter ε （≤1） , which measures the smallness of the deformation, is employed to reduce the governing Boundary Value Problem （BVP） to a simpler BVP for the first-order correction of the potential function. The first-order potential function and, hence, the first-order reflection and transmission coefficients are obtained by the method based on Fourier transform technique as well as Green＇s integral theorem with the introduction of appropriate Green＇s function. Two special examples of bottom deformation： the exponentially damped deformation and the sinusoidal ripple bed, are considered to validate the results. For the particular example of a patch of sinusoidal ripples, the resonant interaction between the bed and the upper surface of the fluid is attained in the neighborhood of a singularity, when the ripples wavenumbers of the bottom deformation become approximately twice the components of the incident field wavenumber along the positive x -direction. Also, the main advantage of the present study is that the results for the values of reflection and transmission coefficients are found to satisfy the energy-balance relation almost accurately.展开更多
In this paper, we use perturbing families of gernerlized Lyapunov functions to discuss ' the relative stability of ordinary differential systems in terms of two measures and gain some criteria for this stability o...In this paper, we use perturbing families of gernerlized Lyapunov functions to discuss ' the relative stability of ordinary differential systems in terms of two measures and gain some criteria for this stability of asymptotic.'展开更多
In this paper, we study a class of doubly perturbed neutral stochastic functional equations driven by fractional Brownian motion. Under some non-Lipschitz conditions, we will prove the existence and uniqueness of the ...In this paper, we study a class of doubly perturbed neutral stochastic functional equations driven by fractional Brownian motion. Under some non-Lipschitz conditions, we will prove the existence and uniqueness of the solution to these equations by providing a semimartingale approximation of a fractional stochastic integration.展开更多
The Sobolev space HS（Rd） with s 〉 d/2 contains many important functions such as the bandlimited or rational ones. In this paper we propose a sequence of measurement functions { φj^r,k}∈C H^-S（R^d） to the phase ...The Sobolev space HS（Rd） with s 〉 d/2 contains many important functions such as the bandlimited or rational ones. In this paper we propose a sequence of measurement functions { φj^r,k}∈C H^-S（R^d） to the phase retrieval problem for the real-valued functions in H^s（R^d）. We prove that any real-valued function f ∈ H^s （Rd） can be determined, up to a global sign, by the phaseless measurements {｜（ f, φj^r,k}｜}. It is known that phase retrieval is unstable in infinite dimensional spaces with respect to perturbations of the measurement functions. We examine a special type of perturbations that ensures the stability for the phase-retrieval problem for all the real-valued functions in Hs（Rd） ∩ C1（Rd）, and prove that our iterated reconstruction procedure guarantees uniform convergence for any function f ∈ Hs （Rd）∩ C1 （Rd） whose Fourier transform f is L1-integrable. Moreover, numerical simulations are conducted to test the efficiency of the reconstruction algorithm.展开更多
High-entropy alloys(HEAs)exhibit exceptional catalytic performance due to their complex surface structures.However,the vast number of active binding sites in HEAs,as opposed to conventional alloys,presents a significa...High-entropy alloys(HEAs)exhibit exceptional catalytic performance due to their complex surface structures.However,the vast number of active binding sites in HEAs,as opposed to conventional alloys,presents a significant computational challenge in catalytic applications.To tackle this challenge,robust methods must be developed to efficiently explore the configurational space of HEA catalysts.Here,we introduce a novel approach that combines alchemical perturbation density functional theory(APDFT)with a graph-based correction scheme to explore the binding energy landscape of HEAs.Our results demonstrate that APDFT can accurately predict binding energies for isoelectronic permutations in HEAs at minimal computational cost,significantly accelerating configurational space sampling.However,APDFT errors increase substantially when permutations occur near binding sites.To address this issue,we developed a graph-based Gaussian process regression model to correct discrepancies betweenAPDFT and conventional density functional theory values.Our approach enables the prediction of binding energies for hundreds of thousands of configurations with a mean average error of 30 meV,requiring a handful of ab initio simulations.展开更多
Spin excitations play a fundamental role in understanding magnetic properties of materials,and have significant technological implications for magnonic devices.However,accurately modeling these in transition-metal and...Spin excitations play a fundamental role in understanding magnetic properties of materials,and have significant technological implications for magnonic devices.However,accurately modeling these in transition-metal and rare-earth compounds remains a formidable challenge.Here,we present a fully first-principles approach for calculating spin-wave spectra based on time-dependent(TD)density-functional perturbation theory(DFPT),using nonempirical Hubbard functionals.This approach is implemented in a general noncollinear formulation,enabling the study of magnons in both collinear and noncollinear magnetic systems.Unlike methods that rely on empirical Hubbard U parameters to describe the ground state,and Heisenberg Hamiltonians for describing magnetic excitations,the methodology developed here probes directly the dynamical spin susceptibility(efficiently evaluated with TDDFPT throught the Liouville-Lanczos approach),and treats the linear variation of the Hubbard augmentation(in itself calculated non-empirically)in full at a self-consistent level.Furthermore,the method satisfies the Goldstone condition without requiring empirical rescaling of the exchange-correlation kernel or explicit enforcement of sum rules,in contrast to existing state-of-the-art techniques.We benchmark the novel computational scheme on prototypical transition-metal monoxides NiO and MnO,showing remarkable agreement with experiments and highlighting the fundamental role of these newly implemented Hubbard corrections.The method holds great promise for describing collective spin excitations in complex materials containing localized electronic states.展开更多
For the semi-infinite programming （SIP） problem, the authors first convert it into an equivalent nonlinear programming problem with only one inequality constraint by using an integral function, and then propose a sm...For the semi-infinite programming （SIP） problem, the authors first convert it into an equivalent nonlinear programming problem with only one inequality constraint by using an integral function, and then propose a smooth penalty method based on a class of smooth functions. The main feature of this method is that the global solution of the penalty function is not necessarily solved at each iteration, and under mild assumptions, the method is always feasible and efficient when the evaluation of the integral function is not very expensive. The global convergence property is obtained in the absence of any constraint qualifications, that is, any accumulation point of the sequence generated by the algorithm is the solution of the SIP. Moreover, the authors show a perturbation theorem of the method and obtain several interesting results. Furthermore, the authors show that all iterative points remain feasible after a finite number of iterations under the Mangasarian-Fromovitz constraint qualification. Finally, numerical results are given.展开更多
Verification and validation of methods and first-principles software are at the core of computational solid-state physics but are too rarely addressed.We compare four first-principles codes:ABINIT,Quantum ESPRESSO,EPW...Verification and validation of methods and first-principles software are at the core of computational solid-state physics but are too rarely addressed.We compare four first-principles codes:ABINIT,Quantum ESPRESSO,EPW,ZG,and three methods:(i)the Allen-Heine-Cardona theory using density functional perturbation theory(DFPT),(ii)the Allen-Heine-Cardona theory using Wannier function perturbation theory(WFPT),and(iii)an adiabatic non-perturbative frozen-phonon method.For these cases,we compute the real and imaginary parts of the electron-phonon self-energy in diamond and BAs,including dipoles and quadrupoles when interpolating.We find excellent agreement between software that implements the same formalism as well as good agreement between the DFPT and WFPT methods.Importantly,we find that the Deybe-Waller term is momentum dependent which impacts the mass enhancement,yielding approximate results when using the Luttinger approximations.Finally,we compare the electron-phonon spectral functions between ABINIT and EPW and find excellent agreement even away from the band edges.展开更多
The mechanism of a cycloaddition reaction between singlet methylidenesilene and ethylene has been investigated with MP2/6-31G^＊ and B3LYP/6-31G^＊ methods, including geometry optimization and vibrational analysis for...The mechanism of a cycloaddition reaction between singlet methylidenesilene and ethylene has been investigated with MP2/6-31G^＊ and B3LYP/6-31G^＊ methods, including geometry optimization and vibrational analysis for the involved stationary points on the potential energy surface. Energies of the involved conformers were calculated by CCSD（T）//MP2/6-31G＊ and CCSD（T）//B3LYP/6-31 G＊ methods, respectively. The results show that the dominant reaction pathway of the cycloaddition reaction is that a complex intermediate is firstly formed between the two reactants through a barrier-free exothermic reaction of 13.3 kJ/mol, and the complex is then isomefized to a four-membered ring product P2,1 via a transition state TS2.1 with a barrier of 32.0 kJ/mol.展开更多
The diamond anvil cell experiments have revealed that the calcium ferrite(CF)-type aluminous phase is probably an important component of subducted mid-oceanic ridge basalt(MORB) in the lower mantle. In this study, we ...The diamond anvil cell experiments have revealed that the calcium ferrite(CF)-type aluminous phase is probably an important component of subducted mid-oceanic ridge basalt(MORB) in the lower mantle. In this study, we have performed first principles lattice dynamics calculations for the Mg Al_2O_4 end-member of the aluminous phase based on density functional perturbation theory using two functionals within the local density approximation(LDA) and generalized gradient approximation(GGA) for bracketing the calculated properties at their lower and upper limits, respectively. A simple empirical pressure correction at zero temperature has been applied to both LDA and GGA. The results of room-temperature equation of state(EOS) and zero-pressure thermal expansion calculated by GGA with pressure correction have shown the best agreement with available experimental data. The high-pressure and temperature thermodynamic properties have been obtained using the GGA with correction method. The pressure-volume relations are fitted with a third-order high-temperature Birch-Murnaghan EOS. The isobaric heat capacity, the coefficient of thermal expansion and isothermal bulk modulus are fitted with polynomials and their coefficients are reported in the range of 0–40 GPa and 300–2000 K. The density profile of MORB estimated using the computational thermo-elastic constants supports the hypothesis that the subducted oceanic slabs could gain enough downwelling forces into the lower mantle.展开更多
Perfect adaptation describes the ability of a biological system to restore its biological function precisely to the pre-perturbation level after being affected by the environmental disturbances.Mathematically,a biolog...Perfect adaptation describes the ability of a biological system to restore its biological function precisely to the pre-perturbation level after being affected by the environmental disturbances.Mathematically,a biological system with perfect adaptation can be modelled as an input-output nonlinear system whose output,usually determining the biological function,is asymptotically stable under all input disturbances concerned.In this paper,a quite general input-output mathematical model is employed and the 'functional' of biological function(FBF)- output Lyapunov function- is explored to investigate its perfect adaptation ability.Sufficient condition is established for the systems with FBF to achieve perfect adaptation.Then a sufficient and necessary condition is obtained for the linear systems to possess an output Lyapunov function.Furthermore,it is shown that the 'functional'of receptors activity exists in the perfect adaptation model of E.coh chemotaxis.Different with the existing mathematical surveys on perfect adaptation,most of which are based on the standpoint of control theory,we first investigate this problem using ways of nonlinear systems analysis.展开更多
We introduce an automated,flexible framework(aiida-hubbard)to self-consistently calculate Hubbard U and V parameters from first-principles.By leveraging density-functional perturbation theory,the computation of the Hu...We introduce an automated,flexible framework(aiida-hubbard)to self-consistently calculate Hubbard U and V parameters from first-principles.By leveraging density-functional perturbation theory,the computation of the Hubbard parameters is efficiently parallelized using multiple concurrent and inexpensive primitive cell calculations.Furthermore,the intersite V parameters are defined on-the-fly during the iterative procedure to account for atomic relaxations and diverse coordination environments.We devise a novel,code-agnostic data structure to store Hubbard related information together with the atomistic structure,to enhance the reproducibility of Hubbard-corrected calculations.We demonstrate the scalability and reliability of the framework by computing in high-throughput fashion the self-consistent onsite U and intersite V parameters for 115 Li-containing bulk solids with up to 32 atoms in the unit cell.Our analysis of the Hubbard parameters calculated reveals a significant correlation of the onsite U values on the oxidation state and coordination environment of the atom on which the Hubbard manifold is centered,while intersite V values exhibit a general decay with increasing interatomic distance.We find,e.g.,that the numerical values of U for the 3d orbitals of Fe and Mn can vary up to 3 eV and 6 eV,respectively;their distribution is characterized by typical shifts of about 0.5 eV and 1.0 eV upon change in oxidation state,or local coordination environment.For the intersite V a narrower spread is found,with values ranging between 0.2 eV and 1.6 eV when considering transition metal and oxygen interactions.This framework paves the way for the exploration of redox materials chemistry and high-throughput screening of d and f compounds across diverse research areas,including the discovery and design of novel energy storage materials,as well as other technologically-relevant applications.展开更多
We present a differentiation framework for plane-wave density-functional theory(DFT)that combines the strengths of forward-mode algorithmic differentiation(AD)and density-functional perturbation theory(DFPT).In the re...We present a differentiation framework for plane-wave density-functional theory(DFT)that combines the strengths of forward-mode algorithmic differentiation(AD)and density-functional perturbation theory(DFPT).In the resulting AD-DFPT framework derivatives of any DFT output quantity with respect to any input parameter(e.g.,geometry,density functional or pseudopotential)can be computed accurately without deriving gradient expressions by hand.We implement AD-DFPT into the Density-Functional ToolKit(DFTK)and show its broad applicability.Amongst others we consider the inverse design of a semiconductor band gap,the learning of exchange-correlation functional parameters,or the propagation of DFT parameter uncertainties to relaxed structures.These examples demonstrate a number of promising research avenues opened by gradient-driven workflows in first-principles materials modeling.展开更多
文摘This paper presents an analytical solution for the interaction of electric potentials, electric displacements, elastic deformations, and thermoelasticity, and describes electromagnetoelastic responses and perturbation of the magnetic field vector in hollow structures （cylinder or sphere）, subjected to mechanical load and electric potential. The material properties, thermal expansion coefficient and magnetic permeability of the structure are assumed to be graded in the radial direction by a power law distribution. In the present model we consider the solution for the case of a hollow structure made of viscoelastic isotropic material, reinforced by elastic isotropic fibers, this material is considered as structurally anisotropic material. The exact solutions for stresses and perturbations of the magnetic field vector in FGM hollow structures are determined using the infinitesimal theory of magnetothermoelasticity, and then the hollow structure model with viscoelastic material is solved using the correspondence principle and Illyushin＇s approximation method. Finally, numerical results are carried out and discussed.
文摘A new way of acoustic wave imaging was investigated. By using the Green function theory a system of integral equations,which linked wave number perturbation function with wave field, was firstly deduced. By taking variation on these integral equations an inversion equation,which reflected the relation between the little variation of wave number perturbation function and that of scattering field, was further obtained. Finally, the perturbation functions of some identical targets were reconstructed, and some properties of the novel method including converging speed, inversion accuracy and the abilities to resist random noise and identify complex targets were discussed. Results of numerical simulation show that the method based on the variation principle has great theoretical and applicable value to quantitative nondestructive evaluation.
基金Project supported by the Teaching and Research Award Program for Outstanding Young Teachers in High Education Institutions of MOE, China
文摘Using a first-principles approach based on density functional theory, this paper studies the electronic and dynamical properties of β-V2O5. A smaller band gap and much wider split-off bands have been observed in comparison with α-V2O5. The Raman-and infrared-active modes at the F point of the Brillouin zone are evaluated with LO/TO splitting, where the symbol denotes the longitudinal and transverse optical model. The nonresonant Raman spectrum of a β-V2O5 powder sample is also computed, providing benchmark theoretical results for the assignment of the experimental spectrum. The computed spectrum agrees with the available experimental data very well. This calculation helps to gain a better understanding of the transition from α-to β-V2O5.
基金supported by the National Natural Science Foundation of China(Grant No.51372140)the Youth Scientist Fund of Shandong Province,China(Grant No.BS2011CL025)the Basic Discipline Research Fund of China University of Petroleum,Beijing,China(Grant No.01JB0169)
文摘The geometric structure,electronic structure,and optical properties of CdHg（SCN）4 crystal are calculated by using the density functional perturbation theory and Green function screening Coulomb interaction approximation.The band gap of CdHg（SCN）4 crystal is calculated to be 3.198 eV,which is in good agreement with the experimental value 3.265 eV.The calculated second-order nonlinear optical coefficients are d14 = 1.2906 pm/V and d15 = 5.0928 pm/V,which are in agreement with the experimental results（d14=（1.4 ±0.6） pm/V and d15=（6.0 ±0.9） pm/V）.Moreover,it is found that the contribution to the valence band mainly comes from Cd-4d,Hg-5d states,and the contributions to the valence band top and the conduction band bottom predominantly come from C-2p,N-2p,and S-3p states.The second-order nonlinear optical effect of CdHg（SCN）_4 crystal results mainly from the internal electronic transition of（SCN）^-.
基金Project supported by the National Natural Science Foundation of China(Grant No.11975143)the Natural Science Foundation of Shandong Province of China(Grant No.ZR2018MA017)+1 种基金the Taishan Scholars Program of Shandong Province,China(Grant No.ts20190936)the Shandong University of Science and Technology Research Fund(Grant No.2015TDJH102).
文摘The quantum hydrodynamic model for ion-acoustic waves in plasmas is studied.First,we design a new disturbance expansion to describe the ion fluid velocity and electric field potential.It should be emphasized that the piecewise function perturbation form is new with great difference from the previous perturbation.Then,based on the piecewise function perturbation,a(3+1)-dimensional generalized modified Korteweg–de Vries Zakharov–Kuznetsov(mKdV-ZK)equation is derived for the first time,which is an extended form of the classical mKdV equation and the ZK equation.The(3+1)-dimensional generalized time-space fractional mKdV-ZK equation is constructed using the semi-inverse method and the fractional variational principle.Obviously,it is more accurate to depict some complex plasma processes and phenomena.Further,the conservation laws of the generalized time-space fractional mKdV-ZK equation are discussed.Finally,using the multi-exponential function method,the non-resonant multiwave solutions are constructed,and the characteristics of ion-acoustic waves are well described.
文摘Intrusion detection is critical to guaranteeing the safety of the data in the network.Even though,since Internet commerce has grown at a breakneck pace,network traffic kinds are rising daily,and network behavior characteristics are becoming increasingly complicated,posing significant hurdles to intrusion detection.The challenges in terms of false positives,false negatives,low detection accuracy,high running time,adversarial attacks,uncertain attacks,etc.lead to insecure Intrusion Detection System(IDS).To offset the existing challenge,the work has developed a secure Data Mining Intrusion detection system(DataMIDS)framework using Functional Perturbation(FP)feature selection and Bengio Nesterov Momentum-based Tuned Generative Adversarial Network(BNM-tGAN)attack detection technique.The data mining-based framework provides shallow learning of features and emphasizes feature engineering as well as selection.Initially,the IDS data are analyzed for missing values based on the Marginal Likelihood Fisher Information Matrix technique(MLFIMT)that identifies the relationship among the missing values and attack classes.Based on the analysis,the missing values are classified as Missing Completely at Random(MCAR),Missing at random(MAR),Missing Not at Random(MNAR),and handled according to the types.Thereafter,categorical features are handled followed by feature scaling using Absolute Median Division based Robust Scalar(AMDRS)and the Handling of the imbalanced dataset.The selection of relevant features is initiated using FP that uses‘3’Feature Selection(FS)techniques i.e.,Inverse Chi Square based Flamingo Search(ICS-FSO)wrapper method,Hyperparameter Tuned Threshold based Decision Tree(HpTT-DT)embedded method,and Xavier Normal Distribution based Relief(XavND-Relief)filter method.Finally,the selected features are trained and tested for detecting attacks using BNM-tGAN.The Experimental analysis demonstrates that the introduced DataMIDS framework produces an accurate diagnosis about the attack with low computation time.The work avoids false alarm rate of attacks and remains to be relatively robust against malicious attacks as compared to existing methods.
基金Partially supported by a research grant from Department of Science and Technology(DST),India(No.SB/FTP/MS-003/2013)
文摘The solution of water wave scattering problem involving small deformation on a porous bed in a channel, where the upper surface is bounded above by an infinitely extent rigid horizontal surface, is studied here within the framework of linearized water wave theory. In such a situation, there exists only one mode of waves propagating on the porous surface. A simplified perturbation analysis, involving a small parameter ε （≤1） , which measures the smallness of the deformation, is employed to reduce the governing Boundary Value Problem （BVP） to a simpler BVP for the first-order correction of the potential function. The first-order potential function and, hence, the first-order reflection and transmission coefficients are obtained by the method based on Fourier transform technique as well as Green＇s integral theorem with the introduction of appropriate Green＇s function. Two special examples of bottom deformation： the exponentially damped deformation and the sinusoidal ripple bed, are considered to validate the results. For the particular example of a patch of sinusoidal ripples, the resonant interaction between the bed and the upper surface of the fluid is attained in the neighborhood of a singularity, when the ripples wavenumbers of the bottom deformation become approximately twice the components of the incident field wavenumber along the positive x -direction. Also, the main advantage of the present study is that the results for the values of reflection and transmission coefficients are found to satisfy the energy-balance relation almost accurately.
文摘In this paper, we use perturbing families of gernerlized Lyapunov functions to discuss ' the relative stability of ordinary differential systems in terms of two measures and gain some criteria for this stability of asymptotic.'
文摘In this paper, we study a class of doubly perturbed neutral stochastic functional equations driven by fractional Brownian motion. Under some non-Lipschitz conditions, we will prove the existence and uniqueness of the solution to these equations by providing a semimartingale approximation of a fractional stochastic integration.
基金supported by Natural Science Foundation of China(Grant Nos.61561006 and11501132)Natural Science Foundation of Guangxi(Grant No.2016GXNSFAA380049)the support from NSF under the(Grant Nos.DMS-1403400 and DMS-1712602)
文摘The Sobolev space HS（Rd） with s 〉 d/2 contains many important functions such as the bandlimited or rational ones. In this paper we propose a sequence of measurement functions { φj^r,k}∈C H^-S（R^d） to the phase retrieval problem for the real-valued functions in H^s（R^d）. We prove that any real-valued function f ∈ H^s （Rd） can be determined, up to a global sign, by the phaseless measurements {｜（ f, φj^r,k}｜}. It is known that phase retrieval is unstable in infinite dimensional spaces with respect to perturbations of the measurement functions. We examine a special type of perturbations that ensures the stability for the phase-retrieval problem for all the real-valued functions in Hs（Rd） ∩ C1（Rd）, and prove that our iterated reconstruction procedure guarantees uniform convergence for any function f ∈ Hs （Rd）∩ C1 （Rd） whose Fourier transform f is L1-integrable. Moreover, numerical simulations are conducted to test the efficiency of the reconstruction algorithm.
基金the support of the National Research Council Canada via Contract No.987243New Frontiers in Research Fund(NFRFE-2019-01095)+1 种基金the Natural Sciences and Engineering Research Council of Canada(NSERC)through the Discovery Grant.M.H.gratefully acknowledges the financial support from the Department of Mechanical Engineering at UBC through the Four Years Fellowshipsupported through high-performance computational resources and services provided by Advanced Research Computing at the University of British Columbia and the Digital Research Alliance of Canada.
文摘High-entropy alloys(HEAs)exhibit exceptional catalytic performance due to their complex surface structures.However,the vast number of active binding sites in HEAs,as opposed to conventional alloys,presents a significant computational challenge in catalytic applications.To tackle this challenge,robust methods must be developed to efficiently explore the configurational space of HEA catalysts.Here,we introduce a novel approach that combines alchemical perturbation density functional theory(APDFT)with a graph-based correction scheme to explore the binding energy landscape of HEAs.Our results demonstrate that APDFT can accurately predict binding energies for isoelectronic permutations in HEAs at minimal computational cost,significantly accelerating configurational space sampling.However,APDFT errors increase substantially when permutations occur near binding sites.To address this issue,we developed a graph-based Gaussian process regression model to correct discrepancies betweenAPDFT and conventional density functional theory values.Our approach enables the prediction of binding energies for hundreds of thousands of configurations with a mean average error of 30 meV,requiring a handful of ab initio simulations.
基金support by the NCCR MARVEL,a National Centre of Competence in Research,funded by the Swiss National Science Foundation(Grant number 205602)the Fellowship from the EPFL QSE Center“Many-body neural simulations of quantum materials”(Grant number 10060)supported by a grant from the Swiss National Supercomputing Centre(CSCS)under project ID s1073 and mr33(Piz Daint).
文摘Spin excitations play a fundamental role in understanding magnetic properties of materials,and have significant technological implications for magnonic devices.However,accurately modeling these in transition-metal and rare-earth compounds remains a formidable challenge.Here,we present a fully first-principles approach for calculating spin-wave spectra based on time-dependent(TD)density-functional perturbation theory(DFPT),using nonempirical Hubbard functionals.This approach is implemented in a general noncollinear formulation,enabling the study of magnons in both collinear and noncollinear magnetic systems.Unlike methods that rely on empirical Hubbard U parameters to describe the ground state,and Heisenberg Hamiltonians for describing magnetic excitations,the methodology developed here probes directly the dynamical spin susceptibility(efficiently evaluated with TDDFPT throught the Liouville-Lanczos approach),and treats the linear variation of the Hubbard augmentation(in itself calculated non-empirically)in full at a self-consistent level.Furthermore,the method satisfies the Goldstone condition without requiring empirical rescaling of the exchange-correlation kernel or explicit enforcement of sum rules,in contrast to existing state-of-the-art techniques.We benchmark the novel computational scheme on prototypical transition-metal monoxides NiO and MnO,showing remarkable agreement with experiments and highlighting the fundamental role of these newly implemented Hubbard corrections.The method holds great promise for describing collective spin excitations in complex materials containing localized electronic states.
基金supported by the National Natural Science Foundation of China under Grant Nos.10971118, 10701047 and 10901096the Natural Science Foundation of Shandong Province under Grant Nos. ZR2009AL019 and BS2010SF010
文摘For the semi-infinite programming （SIP） problem, the authors first convert it into an equivalent nonlinear programming problem with only one inequality constraint by using an integral function, and then propose a smooth penalty method based on a class of smooth functions. The main feature of this method is that the global solution of the penalty function is not necessarily solved at each iteration, and under mild assumptions, the method is always feasible and efficient when the evaluation of the integral function is not very expensive. The global convergence property is obtained in the absence of any constraint qualifications, that is, any accumulation point of the sequence generated by the algorithm is the solution of the SIP. Moreover, the authors show a perturbation theorem of the method and obtain several interesting results. Furthermore, the authors show that all iterative points remain feasible after a finite number of iterations under the Mangasarian-Fromovitz constraint qualification. Finally, numerical results are given.
基金supported by the Fonds de la Recherche Scientifique-FNRS under Grants number T.0183.23(PDR)and T.W011.23(PDR-WEAVE)supported by the Walloon Region in the strategic axe FRFS-WEL-T.J.-M.L.and C.-H.P.acknowledge support from Korean-NRF No-2023R1A2C1007297+1 种基金Computational resources have been provided by the PRACE award granting access to MareNostrum4 at Barcelona Supercomputing Center(BSC),Spain and Discoverer in SofiaTech,Bulgaria(OptoSpin project id.2020225411)by the Consortium desÉquipements de Calcul Intensif(CÉCI),funded by the FRS-FNRS under Grant No.2.5020.11 and by the Walloon Region,as well as computational resources awarded on the Belgian share of the EuroHPC LUMI supercomputer.
文摘Verification and validation of methods and first-principles software are at the core of computational solid-state physics but are too rarely addressed.We compare four first-principles codes:ABINIT,Quantum ESPRESSO,EPW,ZG,and three methods:(i)the Allen-Heine-Cardona theory using density functional perturbation theory(DFPT),(ii)the Allen-Heine-Cardona theory using Wannier function perturbation theory(WFPT),and(iii)an adiabatic non-perturbative frozen-phonon method.For these cases,we compute the real and imaginary parts of the electron-phonon self-energy in diamond and BAs,including dipoles and quadrupoles when interpolating.We find excellent agreement between software that implements the same formalism as well as good agreement between the DFPT and WFPT methods.Importantly,we find that the Deybe-Waller term is momentum dependent which impacts the mass enhancement,yielding approximate results when using the Luttinger approximations.Finally,we compare the electron-phonon spectral functions between ABINIT and EPW and find excellent agreement even away from the band edges.
基金Project supported by the Natural Science Foundation of Shandong Province of China （No. Y2002B07）.
文摘The mechanism of a cycloaddition reaction between singlet methylidenesilene and ethylene has been investigated with MP2/6-31G^＊ and B3LYP/6-31G^＊ methods, including geometry optimization and vibrational analysis for the involved stationary points on the potential energy surface. Energies of the involved conformers were calculated by CCSD（T）//MP2/6-31G＊ and CCSD（T）//B3LYP/6-31 G＊ methods, respectively. The results show that the dominant reaction pathway of the cycloaddition reaction is that a complex intermediate is firstly formed between the two reactants through a barrier-free exothermic reaction of 13.3 kJ/mol, and the complex is then isomefized to a four-membered ring product P2,1 via a transition state TS2.1 with a barrier of 32.0 kJ/mol.
基金supported by the State Key Development Program of Basic Research of China(Grant No.2014CB845905)the National Natural Science Foundation of China(Grant Nos.41402033&40973003)the Fundamental Research Funds for the Central Universities(Grant No.20620140385)
文摘The diamond anvil cell experiments have revealed that the calcium ferrite(CF)-type aluminous phase is probably an important component of subducted mid-oceanic ridge basalt(MORB) in the lower mantle. In this study, we have performed first principles lattice dynamics calculations for the Mg Al_2O_4 end-member of the aluminous phase based on density functional perturbation theory using two functionals within the local density approximation(LDA) and generalized gradient approximation(GGA) for bracketing the calculated properties at their lower and upper limits, respectively. A simple empirical pressure correction at zero temperature has been applied to both LDA and GGA. The results of room-temperature equation of state(EOS) and zero-pressure thermal expansion calculated by GGA with pressure correction have shown the best agreement with available experimental data. The high-pressure and temperature thermodynamic properties have been obtained using the GGA with correction method. The pressure-volume relations are fitted with a third-order high-temperature Birch-Murnaghan EOS. The isobaric heat capacity, the coefficient of thermal expansion and isothermal bulk modulus are fitted with polynomials and their coefficients are reported in the range of 0–40 GPa and 300–2000 K. The density profile of MORB estimated using the computational thermo-elastic constants supports the hypothesis that the subducted oceanic slabs could gain enough downwelling forces into the lower mantle.
文摘Perfect adaptation describes the ability of a biological system to restore its biological function precisely to the pre-perturbation level after being affected by the environmental disturbances.Mathematically,a biological system with perfect adaptation can be modelled as an input-output nonlinear system whose output,usually determining the biological function,is asymptotically stable under all input disturbances concerned.In this paper,a quite general input-output mathematical model is employed and the 'functional' of biological function(FBF)- output Lyapunov function- is explored to investigate its perfect adaptation ability.Sufficient condition is established for the systems with FBF to achieve perfect adaptation.Then a sufficient and necessary condition is obtained for the linear systems to possess an output Lyapunov function.Furthermore,it is shown that the 'functional'of receptors activity exists in the perfect adaptation model of E.coh chemotaxis.Different with the existing mathematical surveys on perfect adaptation,most of which are based on the standpoint of control theory,we first investigate this problem using ways of nonlinear systems analysis.
基金support from the Deutsche Forschungsgemeinschaft(DFG)under Germany’s Excellence Strategy(EXC 2077,No.390741603,University Allowance,University of Bremen),Lucio Colombi Ciacchi,the host of the“U Bremen Excellence Chair Program”C.M.and E.M acknowledge funding by MaX“Materials Design at the Exascale”,a Center of Excellence co-funded by the European High Performance Computing Joint Undertaking(JU)and participating countries under grant agreement No.101093374+4 种基金M.B.acknowledges funding by the European Centre of Excellence MaX“Materials design at the Exascale”(grant no.824143)and by the SwissTwins project,funded by the Swiss State Secretariat for Education,Research and Innovation(SERI)I.T.acknowledges funding by the Swiss National Science Foundation(grant no.200021-227641)We acknowledge support by the NCCR MARVEL,a National Centre of Competence in Research,funded by the Swiss National Science Foundation(Grant number 205602)This work was supported by a grant from the Swiss National Supercomputing Centre(CSCS)under project ID 465000416(LUMI-G).We thank Julian Geiger,Gabriel Joalland,Austin Zadoks and Timo Reents for useful discussions and feedbacks.
文摘We introduce an automated,flexible framework(aiida-hubbard)to self-consistently calculate Hubbard U and V parameters from first-principles.By leveraging density-functional perturbation theory,the computation of the Hubbard parameters is efficiently parallelized using multiple concurrent and inexpensive primitive cell calculations.Furthermore,the intersite V parameters are defined on-the-fly during the iterative procedure to account for atomic relaxations and diverse coordination environments.We devise a novel,code-agnostic data structure to store Hubbard related information together with the atomistic structure,to enhance the reproducibility of Hubbard-corrected calculations.We demonstrate the scalability and reliability of the framework by computing in high-throughput fashion the self-consistent onsite U and intersite V parameters for 115 Li-containing bulk solids with up to 32 atoms in the unit cell.Our analysis of the Hubbard parameters calculated reveals a significant correlation of the onsite U values on the oxidation state and coordination environment of the atom on which the Hubbard manifold is centered,while intersite V values exhibit a general decay with increasing interatomic distance.We find,e.g.,that the numerical values of U for the 3d orbitals of Fe and Mn can vary up to 3 eV and 6 eV,respectively;their distribution is characterized by typical shifts of about 0.5 eV and 1.0 eV upon change in oxidation state,or local coordination environment.For the intersite V a narrower spread is found,with values ranging between 0.2 eV and 1.6 eV when considering transition metal and oxygen interactions.This framework paves the way for the exploration of redox materials chemistry and high-throughput screening of d and f compounds across diverse research areas,including the discovery and design of novel energy storage materials,as well as other technologically-relevant applications.
基金supported by the Swiss National Science Foundation (SNSF, Grant No. 221186)the NCCR MARVEL, a National Centre of Competence in Research, funded by the SNSF (Grant No. 205602). The funder played no role in study design, data collection, analysis and interpretation of data, or the writing of this manuscript. Fruitful discussions with Andrea Azzali, Gaspard Kemlin, Antoine Levitt, Uwe Naumann, Étienne Polack, and Markus Towara on the technical aspects of our AD-DFPT implementation and with Giovanni Pizzi regarding the pseudopotential training example are gratefully acknowledged.
文摘We present a differentiation framework for plane-wave density-functional theory(DFT)that combines the strengths of forward-mode algorithmic differentiation(AD)and density-functional perturbation theory(DFPT).In the resulting AD-DFPT framework derivatives of any DFT output quantity with respect to any input parameter(e.g.,geometry,density functional or pseudopotential)can be computed accurately without deriving gradient expressions by hand.We implement AD-DFPT into the Density-Functional ToolKit(DFTK)and show its broad applicability.Amongst others we consider the inverse design of a semiconductor band gap,the learning of exchange-correlation functional parameters,or the propagation of DFT parameter uncertainties to relaxed structures.These examples demonstrate a number of promising research avenues opened by gradient-driven workflows in first-principles materials modeling.
