期刊文献+
共找到489篇文章
< 1 2 25 >
每页显示 20 50 100
A FLEXIBLE OBJECTIVE-CONSTRAINT APPROACH AND A NEW ALGORITHM FOR CONSTRUCTING THE PARETO FRONT OF MULTIOBJECTIVE OPTIMIZATION PROBLEMS
1
作者 N.HOSEINPOOR M.GHAZNAVI 《Acta Mathematica Scientia》 SCIE CSCD 2024年第2期702-720,共19页
In this article, a novel scalarization technique, called the improved objective-constraint approach, is introduced to find efficient solutions of a given multiobjective programming problem. The presented scalarized pr... In this article, a novel scalarization technique, called the improved objective-constraint approach, is introduced to find efficient solutions of a given multiobjective programming problem. The presented scalarized problem extends the objective-constraint problem. It is demonstrated that how adding variables to the scalarized problem, can lead to find conditions for (weakly, properly) Pareto optimal solutions. Applying the obtained necessary and sufficient conditions, two algorithms for generating the Pareto front approximation of bi-objective and three-objective programming problems are designed. These algorithms are easy to implement and can achieve an even approximation of (weakly, properly) Pareto optimal solutions. These algorithms can be generalized for optimization problems with more than three criterion functions, too. The effectiveness and capability of the algorithms are demonstrated in test problems. 展开更多
关键词 multiobjective optimization Pareto front SCALARIZATION objective-constraint approach proper efficient solution
下载PDF
A GENERALIZED SCALAR AUXILIARY VARIABLE METHOD FOR THE TIME-DEPENDENT GINZBURG-LANDAU EQUATIONS
2
作者 司智勇 《Acta Mathematica Scientia》 SCIE CSCD 2024年第2期650-670,共21页
This paper develops a generalized scalar auxiliary variable(SAV)method for the time-dependent Ginzburg-Landau equations.The backward Euler method is used for discretizing the temporal derivative of the time-dependent ... This paper develops a generalized scalar auxiliary variable(SAV)method for the time-dependent Ginzburg-Landau equations.The backward Euler method is used for discretizing the temporal derivative of the time-dependent Ginzburg-Landau equations.In this method,the system is decoupled and linearized to avoid solving the non-linear equation at each step.The theoretical analysis proves that the generalized SAV method can preserve the maximum bound principle and energy stability,and this is confirmed by the numerical result,and also shows that the numerical algorithm is stable. 展开更多
关键词 time-dependent Ginzburg-Landau equation generalized scalar auxiliary variable algorithm maximum bound principle energy stability
下载PDF
Helmholtz decomposition with a scalar Poisson equation in elastic anisotropic media
3
作者 Xin-Yu Fang Gang Yao +3 位作者 Qing-Qing Zheng Ping-Min Zhang Di Wu Feng-Lin Niu 《Petroleum Science》 SCIE EI CAS CSCD 2024年第3期1597-1610,共14页
P-and S-wave separation plays an important role in elastic reverse-time migration.It can reduce the artifacts caused by crosstalk between different modes and improve image quality.In addition,P-and Swave separation ca... P-and S-wave separation plays an important role in elastic reverse-time migration.It can reduce the artifacts caused by crosstalk between different modes and improve image quality.In addition,P-and Swave separation can also be used to better understand and distinguish wave types in complex media.At present,the methods for separating wave modes in anisotropic media mainly include spatial nonstationary filtering,low-rank approximation,and vector Poisson equation.Most of these methods require multiple Fourier transforms or the calculation of large matrices,which require high computational costs for problems with large scale.In this paper,an efficient method is proposed to separate the wave mode for anisotropic media by using a scalar anisotropic Poisson operator in the spatial domain.For 2D problems,the computational complexity required by this method is 1/2 of the methods based on solving a vector Poisson equation.Therefore,compared with existing methods based on pseudoHelmholtz decomposition operators,this method can significantly reduce the computational cost.Numerical examples also show that the P and S waves decomposed by this method not only have the correct amplitude and phase relative to the input wavefield but also can reduce the computational complexity significantly. 展开更多
关键词 Anisotropic media Scalar anisotropic Poisson equation Improved elastic wavefield decomposition
下载PDF
High-Order Decoupled and Bound Preserving Local Discontinuous Galerkin Methods for a Class of Chemotaxis Models
4
作者 Wei Zheng Yan Xu 《Communications on Applied Mathematics and Computation》 EI 2024年第1期372-398,共27页
In this paper,we explore bound preserving and high-order accurate local discontinuous Galerkin(LDG)schemes to solve a class of chemotaxis models,including the classical Keller-Segel(KS)model and two other density-depe... In this paper,we explore bound preserving and high-order accurate local discontinuous Galerkin(LDG)schemes to solve a class of chemotaxis models,including the classical Keller-Segel(KS)model and two other density-dependent problems.We use the convex splitting method,the variant energy quadratization method,and the scalar auxiliary variable method coupled with the LDG method to construct first-order temporal accurate schemes based on the gradient flow structure of the models.These semi-implicit schemes are decoupled,energy stable,and can be extended to high accuracy schemes using the semi-implicit spectral deferred correction method.Many bound preserving DG discretizations are only worked on explicit time integration methods and are difficult to get high-order accuracy.To overcome these difficulties,we use the Lagrange multipliers to enforce the implicit or semi-implicit LDG schemes to satisfy the bound constraints at each time step.This bound preserving limiter results in the Karush-Kuhn-Tucker condition,which can be solved by an efficient active set semi-smooth Newton method.Various numerical experiments illustrate the high-order accuracy and the effect of bound preserving. 展开更多
关键词 Chemotaxis models Local discontinuous Galerkin(LDG)scheme Convex splitting method Variant energy quadratization method Scalar auxiliary variable method Spectral deferred correction method
下载PDF
On Scalar Planck Waves
5
作者 Lewis Nash 《Journal of High Energy Physics, Gravitation and Cosmology》 CAS 2024年第4期1551-1563,共13页
The sound of space-time at the large scale is observed in the form of gravitational waves, which are disturbances in space-time produced by wavelike distortions (or kinks) in the gravitational field of an accelerating... The sound of space-time at the large scale is observed in the form of gravitational waves, which are disturbances in space-time produced by wavelike distortions (or kinks) in the gravitational field of an accelerating parcel or distribution of energy. In this study, we investigate a hypothetical wave mode of quantum space-time, which suggests the existence of scalar Planck waves. According to this hypothesis, the sound of quantum space-time corresponds to kinks propagating in the gravitational displacement field of an oscillating energy density. In evaluating the emission of scalar Planck waves and their effect on the geometry of space-time, one finds that they not only transport a vanishingly small amount of energy but can also be used to simulate gravity. 展开更多
关键词 Scalar Planck Waves Quantum Space-Time Dynamics Gravitational Waves Gravitational Displacement Field Artificial Gravity
下载PDF
Structure of Massive “Standard Model” Particles
6
作者 Hans-Peter Morsch 《Journal of High Energy Physics, Gravitation and Cosmology》 CAS 2024年第4期1670-1674,共5页
The massive vector bosons Z o, W ± and the scalar Higgs-boson H o assumed in weak interaction theory, but also the six quarks required in strong interactions are well understood in an alternative quantum field th... The massive vector bosons Z o, W ± and the scalar Higgs-boson H o assumed in weak interaction theory, but also the six quarks required in strong interactions are well understood in an alternative quantum field theory of fermions and bosons: Z o and W ± as well as all quark-antiquark states (here only the tt¯state is discussed) are described by bound states with scalar coupling between their massless constituents and have a structure similar to leptons. However, the scalar Higgs-boson H o corresponds to a state with vector coupling between the elementary constituents. Similar scalar states are expected also in the mass region of the mesons ω (0.782 GeV) - Υ ( 9.46 GeV). The underlying calculations can be run on line using the Web-address https://h2909473.stratoserver.net. 展开更多
关键词 Quantum Field Theory of Fermion and Bosons Z o and W ± Boson as Well as the Quark-Antiquark State Are Well Described as Bound States of Massless Fermions and Bosons with Scalar Coupling between the Elementary Constituents The Scalar H o-Boson Involves Vector Coupling between Them
下载PDF
Numerical Modeling of Mass Transfer in the Interaction between River Biofilm and a Turbulent Boundary Layer
7
作者 Falilou Coundoul Evrad M. D. Ngom Frédéric Y. Moulin 《Open Journal of Fluid Dynamics》 2024年第1期1-23,共23页
In this article dedicated to the modeling of vertical mass transfers between the biofilm and the bulk flow, we have, in the first instance, presented the methodology used, followed by the presentation of various resul... In this article dedicated to the modeling of vertical mass transfers between the biofilm and the bulk flow, we have, in the first instance, presented the methodology used, followed by the presentation of various results obtained through analyses conducted on velocity fields, different fluxes, and overall transfer coefficients. Due to numerical constraints (resolution of relevant spatial scales), we have restricted the analysis to low Schmidt numbers (S<sub>c</sub><sub></sub>=0.1, S<sub>c</sub></sub>=1, and S<sub>c</sub></sub>=10) and a single roughness Reynolds number (Re<sub>*</sub>=150). The analysis of instantaneous concentration fields from various simulations revealed logarithmic concentration profiles above the canopy. In this zone, the concentration is relatively homogeneous for longer times. The analysis of results also showed that the contribution of molecular diffusion to the total flux depends on the Schmidt number. This contribution is negligible for Schmidt numbers S<sub>c</sub></sub>≥0.1, but nearly balances the turbulent flux for S<sub>c</sub></sub>=0.1. In the canopy, the local Sherwood number, given by the ratio of the total flux (within or above the canopy) to the molecular diffusion flux at the wall, also depends on the Schmidt number and varies significantly between the canopy and the region above. The exchange velocity, a purely hydrodynamic parameter, is independent of the Schmidt number and is on the order of 10% of in the present case. This study also reveals that nutrient absorption by organisms near the wall depends on the Schmidt number. Such absorption is facilitated by lower Schmidt numbers. 展开更多
关键词 Epilithic Biofilm Passive Scalar Transport Direct Numerical Simulation NAVIER-STOKES
下载PDF
Dynamic of Scalar Bosons in Aharonov-Bohm Magnetic Field
8
作者 Frédéric D. Y. Zongo 《Journal of Applied Mathematics and Physics》 2024年第1期268-276,共9页
We study the dynamic of scalar bosons in the presence of Aharonov-Bohm magnetic field. First, we give the differential equation that governs this dynamic. Secondly, we use variational techniques to show that the follo... We study the dynamic of scalar bosons in the presence of Aharonov-Bohm magnetic field. First, we give the differential equation that governs this dynamic. Secondly, we use variational techniques to show that the following Schrödinger-Newton equation: , where A is an Aharonov-Bohm magnetic potential, has a unique ground-state solution. 展开更多
关键词 Scalar Boson Aharonov-Bohm Magnetic Field Schrödinger-Newton Equation Ground-State Solution
下载PDF
MAXWELL-EINSTEIN METRICS ON COMPLETIONS OF CERTAIN C* BUNDLES 被引量:2
9
作者 关庄丹 《Acta Mathematica Scientia》 SCIE CSCD 2023年第1期363-372,共10页
In this paper,we prove that for some completions of certain fiber bundles there is a Maxwell-Einstein metric conformally related to any given Kahler class.
关键词 Hermitian metrics Maxwell-Einstein metrics complex manifolds scalar curvature fiber bundle almost homogeneous manifolds
下载PDF
Dark Contributions to h→μ^(+)μ^(-) in the Presence of a μ-Flavored Vector-Like Lepton
10
作者 Bibhabasu De 《Chinese Physics Letters》 SCIE EI CAS CSCD 2023年第4期91-94,共4页
A simple extension of the standard model(SM) with a μ-flavored vector-like lepton(VLL) doublet and a real singlet scalar can have an interesting implication to the h→μ^(+)μ^(-)decay while offering the simplest pos... A simple extension of the standard model(SM) with a μ-flavored vector-like lepton(VLL) doublet and a real singlet scalar can have an interesting implication to the h→μ^(+)μ^(-)decay while offering the simplest possible explanation for the dark matter(DM) phenomenology.Assuming the real singlet scalar to be a viable DM candidate,it has been shown that the muon Yukawa coupling can have a negative contribution at the oneloop order if the 2^(nd) generation SM leptons are allowed to couple with the VLL doublet.The stringent direct detection bounds corresponding to a real singlet scalar DM can easily be relaxed if the SM quark sector was augmented with a dimension-6 operator at some new physics(NP) scale Λ_(NP).Thus,this model presents a significant phenomenological study where the muon Yukawa coupling can be corrected within a real singlet scalar DM framework.The considered parameter space can be tested/constrained through the high luminosity run of the LHC(HL-LHC) and future direct detection experiments. 展开更多
关键词 SCALAR SINGLET allowed
下载PDF
Space-time correlations of passive scalar in Kraichnan model
11
作者 Ping-Fan Yang Liubin Pan Guowei He 《Theoretical & Applied Mechanics Letters》 CSCD 2023年第5期338-340,共3页
We consider the two-point,two-time(space-time)correlation of passive scalar R(r,τ)in the Kraichnan model under the assumption of homogeneity and isotropy.Using the fine-gird PDF method,we find that R(r,τ)satisfies a... We consider the two-point,two-time(space-time)correlation of passive scalar R(r,τ)in the Kraichnan model under the assumption of homogeneity and isotropy.Using the fine-gird PDF method,we find that R(r,τ)satisfies a diffusion equation with constant diffusion coefficient determined by velocity variance and molecular diffusion.Itssolution can be expressed in terms of the two-point,one time correlation of passive scalar,i.e.,R(r,0).Moreover,the decorrelation o R(k,τ),which is the Fourier transform of R(r,τ),is determined byR(k,0)and a diffusion kernal. 展开更多
关键词 Space-time correlation Passive scalar Kraichnan model
下载PDF
A Vector Tensor Calculus Description of a Euclidean Space
12
作者 Pavel Grinfeld 《Journal of Applied Mathematics and Physics》 2023年第3期705-720,共16页
We present a tensor description of Euclidean spaces that emphasizes the use of geometric vectors which leads to greater geometric insight and a higher degree of organization in analytical expressions. We demonstrate t... We present a tensor description of Euclidean spaces that emphasizes the use of geometric vectors which leads to greater geometric insight and a higher degree of organization in analytical expressions. We demonstrate the effectiveness of the approach by proving a number of integral identities with vector integrands. The presented approach may be aptly described as absolute vector calculus or as vector tensor calculus. 展开更多
关键词 Tensor Calculus Differential Geometry Embedded Surfaces and Curves Scalar Curvature Gaussian Curvature
下载PDF
A Unified Definition of Electrostatic and Magnetic Fields
13
作者 Geoffroy Auvert 《Open Journal of Applied Sciences》 CAS 2023年第5期793-801,共9页
This article originates from the observation that field lines are drawn using distinctive rules in magnetic field and electrostatic fields. It aims at reconciliating the definitions of these fields and thus reaching a... This article originates from the observation that field lines are drawn using distinctive rules in magnetic field and electrostatic fields. It aims at reconciliating the definitions of these fields and thus reaching a consensus on the interpretation of field lines. Our unified field definition combines three orthogonal vectors and a unique scalar value. Field lines are then defined as isovalue lines of the scalar value, rendering it simpler to interpret in both field types. Specific to our field definition is the use of square root of vector’s cross product so that all vectors have the same physical unit. This enhanced field definition also enables a more efficient calculation of Biot-Savart law. This article is the first of a series allowing the drawing of isovalue contour lines. 展开更多
关键词 Magnetic Field Electrostatic Field Biot-Savart Law Scalar Field Value Equipotential Line Square Root Cross Product
下载PDF
Developing a Secure Framework Using Feature Selection and Attack Detection Technique
14
作者 Mahima Dahiya Nitin Nitin 《Computers, Materials & Continua》 SCIE EI 2023年第2期4183-4201,共19页
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
关键词 Cyber security data mining intrusion detection system(DataMIDS) marginal likelihood fisher information matrix(MLFIM) absolute median deviation based robust scalar(AMD-RS) functional perturbation(FP) inverse chi square based flamingo search optimization(ICS-FSO) hyperparameter tuned threshold based decision tree(HpTT-DT) Xavier normal distribution based relief(XavND-relief) and Bengio Nesterov momentum-based tuned generative adversarial network(BNM-tGAN)
下载PDF
Complex Maxwell’s Equations
15
作者 Mahgoub A. Salih 《Journal of Modern Physics》 2023年第12期1662-1671,共10页
Maxwell’s equations in electromagnetism can be categorized into three dis-tinct groups based on the electromagnetic source when employing quaterni-ons. Each group represents a self-contained system in which Maxwell’... Maxwell’s equations in electromagnetism can be categorized into three dis-tinct groups based on the electromagnetic source when employing quaterni-ons. Each group represents a self-contained system in which Maxwell’s equations are applied and validated concurrently, in contrast to the previous approach that did not account for this. It has been noted that the formulation of these Maxwell equations ultimately results in the formulation of Max-well’s equations utilizing the scalar function. 展开更多
关键词 Maxwell’s Equations Scalar Function Proca Equation Gage Transformation QUATERNION
下载PDF
Bi-normalized response spectra and scalar periods for developing uniform seismic design spectra 被引量:3
16
作者 徐龙军 谢礼立 《Journal of Southeast University(English Edition)》 EI CAS 2007年第2期266-271,共6页
Aiming at the uniform features of acceleration response spectra, two scalar periods-the response spectral predominant period Tp and the smoothed spectral predominant period To are employed to normalize the abscissa of... Aiming at the uniform features of acceleration response spectra, two scalar periods-the response spectral predominant period Tp and the smoothed spectral predominant period To are employed to normalize the abscissa of the normalized response spectra (NRS) of ground motions, respectively. Engineering characteristics of 5% -damped NRS, and the bi-normalized response spectra (BNRS) are investigated accounting for the effects of soil condition and fault distance. Nearly 600 horizontal ground motion components during the Chi-Chi earthquake are included in the analysis. It shows that the NRS strongly depends on soil condition and fault distance. However, soil condition and distance have only a slight influence on two kinds of BNRS. Dispersion analysis indicates that such normalization can reduce scatter in the derivation of response spectral shapes. Finally, a parametric analysis of the scalar periods (Tp, To) is performed and then compared with those of previous studies. These special and particular aspects of earthquake response spectra and scalar periods need to be considered in developing earthquake-resistant design criteria. 展开更多
关键词 ground motion normalized response spectrum bi-normalized response spectra scalar period
下载PDF
广义Sasakian空间形式中反不变ξ^⊥-子流形的一个不等式 被引量:1
17
作者 杜锋 吴传喜 刘怀元 《湖北大学学报(自然科学版)》 CAS 北大核心 2008年第2期117-119,共3页
对推广的Sasakian空间形式,即广义Sasakian空间形式中的反不变ξ⊥-子流形作了一些研究,并得到一个关于scalar曲率与平均曲率算子的平方间的一个不等式‖H‖2≥(2(n+2)/n2(n-1))τ-(n+2/n)f1.
关键词 广义Sasakian空间形式 scalar曲率 反不变ξ^⊥-子流形
下载PDF
Fast and secure elliptic curve scalar multiplication algorithm based on special addition chains
18
作者 刘双根 胡予濮 《Journal of Southeast University(English Edition)》 EI CAS 2008年第1期29-32,共4页
To resist the side chaimel attacks of elliptic curve cryptography, a new fast and secure point multiplication algorithm is proposed. The algorithm is based on a particular kind of addition chains involving only additi... To resist the side chaimel attacks of elliptic curve cryptography, a new fast and secure point multiplication algorithm is proposed. The algorithm is based on a particular kind of addition chains involving only additions, providing a natural protection against side channel attacks. Moreover, the new addition formulae that take into account the specific structure of those chains making point multiplication very efficient are proposed. The point multiplication algorithm only needs 1 719 multiplications for the SAC260 of 160-bit integers. For chains of length from 280 to 260, the proposed method outperforms all the previous methods with a gain of 26% to 31% over double-and add, 16% to22% over NAF, 7% to 13% over4-NAF and 1% to 8% over the present best algorithm--double-base chain. 展开更多
关键词 scalar multiplication algorithm special addition chains side channel attacks double base chain
下载PDF
SUPER EFFICIENCY IN THE NEARLY CONE-SUBCONVEXLIKE VECTOR OPTIMIZATION WITH SET-VALUED FUNCTIONS 被引量:14
19
作者 徐义红 刘三阳 《Acta Mathematica Scientia》 SCIE CSCD 2005年第1期152-160,共9页
Some properties for convex cones are discussed, which are used to obtain an equivalent condition and another important property for nearly cone-subconvexlike set-valued functions. Under the nearly cone-subconvexlikene... Some properties for convex cones are discussed, which are used to obtain an equivalent condition and another important property for nearly cone-subconvexlike set-valued functions. Under the nearly cone-subconvexlikeness, some characterizations of the super efficiency are given in terms of scalarization and Lagrangian multipliers. Related results are generalized. 展开更多
关键词 Nearly cone-subconvexlikeness convex cones super efficiency SCALARIZATION Lagrangian multipliers
下载PDF
A Parameterization Scheme of Surface Turbulent Momentum and Sensible Heat over the Gobi Underlying Surface 被引量:9
20
作者 张强 黄荣辉 田辉 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2003年第1期111-118,共8页
The parameterization of surface turbulent fluxes over the Gobi Desert in arid regions is studied by using rationally screened observational data. First, the characteristics of Monin-Obukhov similarity functions are an... The parameterization of surface turbulent fluxes over the Gobi Desert in arid regions is studied by using rationally screened observational data. First, the characteristics of Monin-Obukhov similarity functions are analyzed and their empirical formulae are fitted. The results show that fitted curves of changes of similarity functions of wind speed and temperature with stability parameter differ little from the typical empirical curves and are within the ranges of scatter of the empirical curves, but their values in the neutral condition arc different from the typical values to some extent. Furthermore, average values of momentum and scalar (sensible heat) roughness lengths as well as changes of scalar roughness length with friction velocity are determined by utilizing the data. It is found that the average values of scalar roughness length are about one order smaller than that of the momentum roughness length and decrease with increasing friction velocity, but they are evidently larger than their theoretically forecasted values. 展开更多
关键词 GOBI surface turbulent flux PARAMETERIZATION similarity functions scalar roughness length
下载PDF
上一页 1 2 25 下一页 到第
使用帮助 返回顶部