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聚合物pVT关系状态方程
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作者 华岱 王建 《塑料》 CAS CSCD 北大核心 2024年第3期109-116,共8页
聚合物的比体积(V)随压力(p)和温度(T)的变化过程主要通过聚合物的压力-比体积-温度(pVT)关系状态方程(EOS)进行描述。聚合物pVT关系状态方程可用作计算一定温度和压力条件下,聚合物的比体积,是研究聚合物相态演变及物质掺混分离规律的... 聚合物的比体积(V)随压力(p)和温度(T)的变化过程主要通过聚合物的压力-比体积-温度(pVT)关系状态方程(EOS)进行描述。聚合物pVT关系状态方程可用作计算一定温度和压力条件下,聚合物的比体积,是研究聚合物相态演变及物质掺混分离规律的重要依据,也是高分子物理和聚合物加工模拟计算必不可少的模型之一。采用理论/半理论和经验方法建立了不同类型及特点的聚合物pVT关系状态方程,根据应用的不同需求而存在显著差别。随着高分子领域数字化智能化的发展,研究并建立了具有适用性和高预测精度的聚合物pVT关系状态方程,对新聚合物材料的开发和新型聚合物加工方法的建立具有重要意义。 展开更多
关键词 聚合物pVT关系 状态方程 胞腔模型 晶格流体 微扰理论 经验模型 人工神经网络
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The Construction of a Learning-Oriented Speaking Assessment Model in College English Based on the Online Diagnostic Assessment
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作者 hua dai 《Journal of Contemporary Educational Research》 2024年第2期26-33,共8页
Since language is a tool for communication,proficiency in English communication is a fundamental necessity for talent in the 21st century.However,surveys reveal that most college students at private colleges possess i... Since language is a tool for communication,proficiency in English communication is a fundamental necessity for talent in the 21st century.However,surveys reveal that most college students at private colleges possess inadequate oral English skills,and what some have learned is“mute English.”Therefore,developing their English-speaking skills is another challenge faced by students attending private schools.Online diagnostic assessment methods are growing globally with the use of technology.UDig diagnostic assessment system is one of the online English diagnostic assessment platforms currently being widely used in China.Therefore,the present work is conducted to investigate and conduct an oral English learning-oriented assessment model in college English using the online diagnostic assessment.With the research result,it is hoped that the study could provide useful information for improving UDig system and make a better use of it in college oral English learning and teaching. 展开更多
关键词 Oral English assessment Diagnostic assessment UDig system Learning-Oriented Assessment(LOA)
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Inverse Eigenvalue Problem in Structural Dynamics Design
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作者 Huiqing Xie hua dai 《Numerical Mathematics A Journal of Chinese Universities(English Series)》 SCIE 2006年第2期97-106,共10页
A kind of inverse eigenvalue problem in structural dynamics design is considered. The problem is formulated as an optimization problem. The properties of this problem are analyzed, and the existence of the optimum sol... A kind of inverse eigenvalue problem in structural dynamics design is considered. The problem is formulated as an optimization problem. The properties of this problem are analyzed, and the existence of the optimum solution is proved. The directional derivative of the objective function is obtained and a necessary condition for a point to be a local minimum point is given. Then a numerical algorithm for solving the problem is presented and a plane-truss problem is discussed to show the applications of the theories and the algorithm. 展开更多
关键词 特征值 逆问题 数值方法 结构设计 动力学
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PRECONDITIONING BLOCK LANCZOS ALGORITHM FOR SOLVING SYMMETRIC EIGENVALUE PROBLEMS 被引量:7
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作者 hua dai Peter Lancaster 《Journal of Computational Mathematics》 SCIE EI CSCD 2000年第4期365-374,共10页
A preconditioned iterative method for computing a few eigenpairs of large sparse symmetric matrices is presented in this paper. The proposed method which combines the preconditioning techniques with the efficiency of ... A preconditioned iterative method for computing a few eigenpairs of large sparse symmetric matrices is presented in this paper. The proposed method which combines the preconditioning techniques with the efficiency of block Lanczos algorithm is suitable for determination of the extreme eigenvalues as well as their multiplicities. The global convergence and the asymptotically quadratic convergence of the new method are also demonstrated. [ABSTRACT FROM AUTHOR] 展开更多
关键词 EIGENVALUE EIGENVECTOR sparse matrices Lanczos method PRECONDITIONING
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ON SMOOTH LU DECOMPOSITIONS WITH APPLICATIONS TO SOLUTIONS OF NONLINEAR EIGENVALUE PROBLEMS 被引量:5
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作者 hua dai Zhong-Zhi Bai 《Journal of Computational Mathematics》 SCIE CSCD 2010年第6期745-766,共22页
We study the smooth LU decomposition of a given analytic functional A-matrix A(A) and its block-analogue. Sufficient conditions for the existence of such matrix decompositions are given, some differentiability about... We study the smooth LU decomposition of a given analytic functional A-matrix A(A) and its block-analogue. Sufficient conditions for the existence of such matrix decompositions are given, some differentiability about certain elements arising from them are proved, and several explicit expressions for derivatives of the specified elements are provided. By using these smooth LU decompositions, we propose two numerical methods for computing multiple nonlinear eigenvalues of A(A), and establish their locally quadratic convergence properties. Several numerical examples are provided to show the feasibility and effectiveness of these new methods. 展开更多
关键词 Matrix-valued function Smooth LU decomposition PIVOTING Nonlinear eigenvalue problem Multiple eigenvalue Newton method.
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二次酸浸法提取煤灰中的氧化铝(英文) 被引量:3
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作者 Pei-wang ZHU hua dai +4 位作者 Lei HAN Xiu-lin XU Le-ming CHENG Qin-hui WANG Zheng-lun SHI 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2015年第2期161-169,共9页
目的:煤灰渣酸浸提铝通常效率不高,主要因为灰渣中存在含铝晶体矿物(如莫来石、尖晶石和长石等)。为解决含铝晶体不易与硫酸反应的问题,本文提出二次酸浸提铝法。创新点:基本实现铝硅分离,第一步酸浸实现非晶态铝的浸出,残渣经焙烧和水... 目的:煤灰渣酸浸提铝通常效率不高,主要因为灰渣中存在含铝晶体矿物(如莫来石、尖晶石和长石等)。为解决含铝晶体不易与硫酸反应的问题,本文提出二次酸浸提铝法。创新点:基本实现铝硅分离,第一步酸浸实现非晶态铝的浸出,残渣经焙烧和水浸后,第二步酸浸实现剩余铝的浸出。方法:1.一次酸浸时,硫酸直接与煤灰渣反应浸出部分氧化铝,提铝残渣加碳酸钠焙烧后,含铝晶体遭到破坏;2.焙烧产物经水浸溶解出硅酸钠,水浸残渣做X射线衍射分析表明其主要为铝硅非晶体活性物质,此时可用硫酸在温和条件下浸出剩余的铝。结论:1.一次酸浸提铝在10 mol/L硫酸、120°C、2 h和1:2固液比的条件下,铝浸出率为81.72%;2.用5 mol/L硫酸二次酸浸时,20°C下铝浸出率已经达到87.31%,100°C下更是达到99.06%;3.综合两次酸浸结果,铝的浸出总效率在97%以上。 展开更多
关键词 煤灰 氧化铝 酸浸 焙烧
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ON EIGENVALUE BOUNDS AND ITERATION METHODS FOR DISCRETE ALGEBRAIC RICCATI EQUATIONS 被引量:1
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作者 hua dai Zhong-Zhi Bai 《Journal of Computational Mathematics》 SCIE CSCD 2011年第3期341-366,共26页
We derive new and tight bounds about the eigenvalues and certain sums of the eigenvalues for the unique symmetric positive definite solutions of the discrete algebraic Riccati equations. These bounds considerably impr... We derive new and tight bounds about the eigenvalues and certain sums of the eigenvalues for the unique symmetric positive definite solutions of the discrete algebraic Riccati equations. These bounds considerably improve the existing ones and treat the cases that have been not discussed in the literature. Besides, they also result in completions for the available bounds about the extremal eigenvalues and the traces of the solutions of the discrete algebraic Riccati equations. We study the fixed-point iteration methods for com- puting the symmetric positive definite solutions of the discrete algebraic Riccati equations and establish their general convergence theory. By making use of the Schulz iteration to partially avoid computing the matrix inversions, we present effective variants of the fixed-point iterations, prove their monotone convergence and estimate their asymptotic convergence rates. Numerical results show that the modified fixed-point iteration methods are feasible and effective solvers for computing the symmetric positive definite solutions of the discrete algebraic Riccati equations. 展开更多
关键词 Discrete algebraic Riccati equation Symmetric positive definite solution Eigenvalue bound Fixed-point iteration Convergence theory.
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GENERALIZED CONJUGATE A-ORTHOGONAL RESIDUAL SQUARED METHOD FOR COMPLEX NON-HERMITIAN LINEAR SYSTEMS 被引量:1
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作者 Jianhua Zhang hua dai 《Journal of Computational Mathematics》 SCIE CSCD 2014年第3期248-265,共18页
Recently numerous numerical experiments on realistic calculation have shown that the conjugate A-orthogonal residual squared (CORS) method is often competitive with other popular methods. However, the CORS method, l... Recently numerous numerical experiments on realistic calculation have shown that the conjugate A-orthogonal residual squared (CORS) method is often competitive with other popular methods. However, the CORS method, like the CGS method, shows irreg- ular convergence, especially appears large intermediate residual norm, which may lead to worse approximate solutions and slower convergence rate. In this paper, we present a new product-type method for solving complex non-Hermitian linear systems based on the bicon- jugate A-orthogonal residual (BiCOR) method, where one of the polynomials is a BiCOR polynomial, and the other is a BiCOR polynomial with the same degree corresponding to different initial residual. Numerical examples are given to illustrate the effectiveness of the proposed method. 展开更多
关键词 Krylov subspace BiCOR method CORS method Complex non-Hermitianlinear systems.
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