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Euler’s First-Order Explicit Method–Peridynamic Differential Operator for Solving Population Balance Equations of the Crystallization Process
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作者 Chunlei Ruan Cengceng Dong +2 位作者 Kunfeng Liang Zhijun Liu Xinru Bao 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第3期3033-3049,共17页
Using Euler’s first-order explicit(EE)method and the peridynamic differential operator(PDDO)to discretize the time and internal crystal-size derivatives,respectively,the Euler’s first-order explicit method–peridyna... Using Euler’s first-order explicit(EE)method and the peridynamic differential operator(PDDO)to discretize the time and internal crystal-size derivatives,respectively,the Euler’s first-order explicit method–peridynamic differential operator(EE–PDDO)was obtained for solving the one-dimensional population balance equation in crystallization.Four different conditions during crystallization were studied:size-independent growth,sizedependent growth in a batch process,nucleation and size-independent growth,and nucleation and size-dependent growth in a continuous process.The high accuracy of the EE–PDDO method was confirmed by comparing it with the numerical results obtained using the second-order upwind and HR-van methods.The method is characterized by non-oscillation and high accuracy,especially in the discontinuous and sharp crystal size distribution.The stability of the EE–PDDO method,choice of weight function in the PDDO method,and optimal time step are also discussed. 展开更多
关键词 Population balance equation CRYsTALLIZATION peridynamic differential operator euler’s first-order explicit method
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Comparative Study on Results of Euler,Improved Euler and Run­ge-Kutta Methods for Solving the Engineering Unknown Problems
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作者 Khaing Khaing Lwin 《Journal of International Education and Practice》 2020年第3期1-6,共6页
The paper presents the comparative study on numerical methods of Euler method,Improved Euler method and fourth-order Runge-Kutta method for solving the engineering problems and applications.The three proposed methods ... The paper presents the comparative study on numerical methods of Euler method,Improved Euler method and fourth-order Runge-Kutta method for solving the engineering problems and applications.The three proposed methods are quite efficient and practically well suited for solving the unknown engineering problems.This paper aims to enhance the teaching and learning quality of teachers and students for various levels.At each point of the interval,the value of y is calculated and compared with its exact value at that point.The next interesting point is the observation of error from those methods.Error in the value of y is the difference between calculated and exact value.A mathematical equation which relates various functions with its derivatives is known as a differential equation.It is a popular field of mathematics because of its application to real-world problems.To calculate the exact values,the approximate values and the errors,the numerical tool such as MATLAB is appropriate for observing the results.This paper mainly concentrates on identifying the method which provides more accurate results.Then the analytical results and calculates their corresponding error were compared in details.The minimum error directly reflected to realize the best method from different numerical methods.According to the analyses from those three approaches,we observed that only the error is nominal for the fourth-order Runge-Kutta method. 展开更多
关键词 Numerical method euler method improved euler method Runge-Kutta method solving the Engineering Problems
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Application of the Improved Kudryashov Method to Solve the Fractional Nonlinear Partial Differential Equations 被引量:2
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作者 Md. Abdus Salam Umme Habiba 《Journal of Applied Mathematics and Physics》 2019年第4期912-920,共9页
Our purpose of this paper is to apply the improved Kudryashov method for solving various types of nonlinear fractional partial differential equations. As an application, the time-space fractional Korteweg-de Vries-Bur... Our purpose of this paper is to apply the improved Kudryashov method for solving various types of nonlinear fractional partial differential equations. As an application, the time-space fractional Korteweg-de Vries-Burger (KdV-Burger) equation is solved using this method and we get some new travelling wave solutions. To acquire our purpose a complex transformation has been also used to reduce nonlinear fractional partial differential equations to nonlinear ordinary differential equations of integer order, in the sense of the Jumarie’s modified Riemann-Liouville derivative. Afterwards, the improved Kudryashov method is implemented and we get our required reliable solutions where the results are justified by mathematical software Maple-13. 展开更多
关键词 improved Kudryashov method Time-space FRACTIONAL KdV-Burger Equation TRAVELLING Wave solutions Jumarie’s Modified Riemann-Liouville Derivative
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On the Approximation of Fractal-Fractional Differential Equations Using Numerical Inverse Laplace Transform Methods
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作者 Kamran Siraj Ahmad +2 位作者 Kamal Shah Thabet Abdeljawad Bahaaeldin Abdalla 《Computer Modeling in Engineering & Sciences》 SCIE EI 2023年第6期2743-2765,共23页
Laplace transform is one of the powerful tools for solving differential equations in engineering and other science subjects.Using the Laplace transform for solving differential equations,however,sometimes leads to sol... Laplace transform is one of the powerful tools for solving differential equations in engineering and other science subjects.Using the Laplace transform for solving differential equations,however,sometimes leads to solutions in the Laplace domain that are not readily invertible to the real domain by analyticalmeans.Thus,we need numerical inversionmethods to convert the obtained solution fromLaplace domain to a real domain.In this paper,we propose a numerical scheme based on Laplace transform and numerical inverse Laplace transform for the approximate solution of fractal-fractional differential equations with orderα,β.Our proposed numerical scheme is based on three main steps.First,we convert the given fractal-fractional differential equation to fractional-differential equation in Riemann-Liouville sense,and then into Caputo sense.Secondly,we transformthe fractional differential equation in Caputo sense to an equivalent equation in Laplace space.Then the solution of the transformed equation is obtained in Laplace domain.Finally,the solution is converted into the real domain using numerical inversion of Laplace transform.Three inversion methods are evaluated in this paper,and their convergence is also discussed.Three test problems are used to validate the inversion methods.We demonstrate our results with the help of tables and figures.The obtained results show that Euler’s and Talbot’s methods performed better than Stehfest’s method. 展开更多
关键词 Fractal-fractional differential equation power law kernel exponential decay kernel Mittag-Leffler kernel Laplace transform euler’s method Talbot’s method stehfest’s method
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Stochastic Programming for Hub Energy Management Considering Uncertainty Using Two-Point Estimate Method and Optimization Algorithm
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作者 Ali S.Alghamdi Mohana Alanazi +4 位作者 Abdulaziz Alanazi Yazeed Qasaymeh Muhammad Zubair Ahmed Bilal Awan M.G.B.Ashiq 《Computer Modeling in Engineering & Sciences》 SCIE EI 2023年第12期2163-2192,共30页
To maximize energy profit with the participation of electricity,natural gas,and district heating networks in the day-ahead market,stochastic scheduling of energy hubs taking into account the uncertainty of photovoltai... To maximize energy profit with the participation of electricity,natural gas,and district heating networks in the day-ahead market,stochastic scheduling of energy hubs taking into account the uncertainty of photovoltaic and wind resources,has been carried out.This has been done using a new meta-heuristic algorithm,improved artificial rabbits optimization(IARO).In this study,the uncertainty of solar and wind energy sources is modeled using Hang’s two-point estimating method(TPEM).The IARO algorithm is applied to calculate the best capacity of hub energy equipment,such as solar and wind renewable energy sources,combined heat and power(CHP)systems,steamboilers,energy storage,and electric cars in the day-aheadmarket.The standard ARO algorithmis developed to mimic the foraging behavior of rabbits,and in this work,the algorithm’s effectiveness in avoiding premature convergence is improved by using the dystudynamic inertia weight technique.The proposed IARO-based scheduling framework’s performance is evaluated against that of traditional ARO,particle swarm optimization(PSO),and salp swarm algorithm(SSA).The findings show that,in comparison to previous approaches,the suggested meta-heuristic scheduling framework based on the IARO has increased energy profit in day-ahead electricity,gas,and heating markets by satisfying the operational and energy hub limitations.Additionally,the results show that TPEM approach dependability consideration decreased hub energy’s profit by 8.995%as compared to deterministic planning. 展开更多
关键词 stochastic energy hub scheduling energy profit UNCERTAINTY Hong’s two-point estimate method improved artificial rabbits optimization
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基于改进T-S模糊模型的弧焊机器人轨迹实时跟踪
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作者 姚江云 王宽田 +1 位作者 李旺昆 梁世华 《组合机床与自动化加工技术》 北大核心 2024年第9期147-152,共6页
针对弧焊机器人在实际作业中受到诸多不确定因素的影响,导致弧焊机器人焊接轨迹偏离预期轨迹的问题,提出一种基于改进T-S(Takagi-Sugeno)模糊模型的弧焊机器人轨迹实时跟踪方法。采用图像识别技术识别并定位焊缝,通过坐标转换,确定焊缝... 针对弧焊机器人在实际作业中受到诸多不确定因素的影响,导致弧焊机器人焊接轨迹偏离预期轨迹的问题,提出一种基于改进T-S(Takagi-Sugeno)模糊模型的弧焊机器人轨迹实时跟踪方法。采用图像识别技术识别并定位焊缝,通过坐标转换,确定焊缝中心线在机器人坐标系中的位置坐标。利用蚁群算法根据焊缝中心线在机器人坐标系中的坐标,搜索从起始位置到目标位置的最优焊接路径。设计了一种改进区间二型T-S模糊模型,通过视觉传感器实时获取新的焊缝信息,计算轨迹误差,以此为输入,利用改进T-S模糊模型对机器人的运动轨迹进行实时调整。实验结果表明,采用改进T-S模糊模型后,机器人轨迹跟踪离散度均降至1 mm以下,弧焊机器人轨迹与预期轨迹高度重合,比传统方法跟踪离散度大大降低。 展开更多
关键词 改进T-s模糊模型 弧焊机器人 焊缝识别与定位 轨迹规划 轨迹实时跟踪方法
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The Zhou’s Method for Solving the Euler Equidimensional Equation
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作者 Pedro Pablo Cárdenas Alzate Jhon Jairo León Salazar Carlos Alberto Rodríguez Varela 《Applied Mathematics》 2016年第17期2165-2173,共9页
In this work, we apply the Zhou’s method [1] or differential transformation method (DTM) for solving the Euler equidimensional equation. The Zhou’s method may be considered as alternative and efficient for finding t... In this work, we apply the Zhou’s method [1] or differential transformation method (DTM) for solving the Euler equidimensional equation. The Zhou’s method may be considered as alternative and efficient for finding the approximate solutions of initial values problems. We prove superiority of this method by applying them on the some Euler type equation, in this case of order 2 and 3 [2]. The power series solution of the reduced equation transforms into an approximate implicit solution of the original equations. The results agreed with the exact solution obtained via transformation to a constant coefficient equation. 展开更多
关键词 Zhou’s method Equidimensional Equation euler Equation DTM
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Improved-GRACE卫星重力轨道参数优化研究 被引量:18
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作者 郑伟 许厚泽 +3 位作者 钟敏 员美娟 彭碧波 周旭华 《大地测量与地球动力学》 CSCD 北大核心 2010年第2期43-48,共6页
基于改进的半解析法,利用激光干涉系统星间速度误差、GPS接收机轨道位置误差和轨道速度误差以及加速度计非保守力误差影响累计大地水准面的联合误差模型,开展了我国Improved-GRACE卫星重力测量计划轨道参数的优化选取论证。模拟结果表明... 基于改进的半解析法,利用激光干涉系统星间速度误差、GPS接收机轨道位置误差和轨道速度误差以及加速度计非保守力误差影响累计大地水准面的联合误差模型,开展了我国Improved-GRACE卫星重力测量计划轨道参数的优化选取论证。模拟结果表明:1)在300阶处,基于350km轨道高度估计累计大地水准面的精度为3.993×10-1m,基于300km和250km轨道高度估计精度分别提高了8.770倍和77.145倍,基于400km和450km轨道高度估计精度分别降低了8.718倍和75.307倍;2)基于50km星间距离估计累计大地水准面的精度为3.993×10-1m,基于110km和220km星间距离估计精度分别降低了1.259倍和1.395倍;3)我国将来首颗Improved-GRACE重力卫星的平均轨道高度和平均星间距离设计为350km与50km较优。 展开更多
关键词 improved-GRACE 轨道高度 星间距离 半解析法 地球重力场
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基于Euler/N-S方程的跨音速非线性静气动弹性问题研究 被引量:2
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作者 郭承鹏 董军 +1 位作者 杨庆华 李俊甫 《航空计算技术》 2006年第6期40-44,共5页
在C-H网格的基础上,采用Jam eson的中心差分有限体积法求解Eu ler/N-S方程,采用结构影响系数法计算结构的弹性变形,用三角元面积加权法和常体积转换法(CVT)实现流固耦合。
关键词 有限体积法 euler/N—s方程 三角元面积加权法 柔度影响系数法 常体积转换法 流固耦合
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Euler-Bernoulli海洋立管涡致强迫振动响应研究 被引量:1
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作者 赵翔 谭明 +1 位作者 李映辉 邵永波 《西南石油大学学报(自然科学版)》 CAS CSCD 北大核心 2023年第4期133-142,共10页
针对海洋立管(Pipe-in-pipe,PIP)系统在海水作用下发生的振动问题,开展了对PIP系统在涡致强迫振动下的动力学响应研究,分析了在涡致强迫振动下海洋立管外管直径、轴向拉力、外激力频率对海洋立管位移响应的影响规律。基于Euler-Bernoull... 针对海洋立管(Pipe-in-pipe,PIP)系统在海水作用下发生的振动问题,开展了对PIP系统在涡致强迫振动下的动力学响应研究,分析了在涡致强迫振动下海洋立管外管直径、轴向拉力、外激力频率对海洋立管位移响应的影响规律。基于Euler-Bernoulli双梁模型,采用Lamb-Oseen涡模型,建立了动力学模型,利用格林函数法求得该强迫振动的稳态响应。结果表明,随着管道直径增加,外激力增加,产生最大力幅值的位置离管道越远;轴向拉力对外部管道的影响较大,对内部管道的影响较小;无因次频率取0.4时,外部管道位移超出允许变形极限,内外管壁发生周期碰撞,易对海洋立管造成损伤。 展开更多
关键词 海洋立管 涡致强迫振动 稳态响应 格林函数法 euler-Bernoulli双梁
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Consistency and Validity of the Mathematical Models and the Solution Methods for BVPs and IVPs Based on Energy Methods and Principle of Virtual Work for Homogeneous Isotropic and Non-Homogeneous Non-Isotropic Solid Continua 被引量:1
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作者 Karan S. Surana Emilio N. Alverio 《Applied Mathematics》 2020年第7期546-578,共33页
Energy methods and the principle of virtual work are commonly used for obtaining solutions of boundary value problems (BVPs) and initial value problems (IVPs) associated with homogeneous, isotropic and non-homogeneous... Energy methods and the principle of virtual work are commonly used for obtaining solutions of boundary value problems (BVPs) and initial value problems (IVPs) associated with homogeneous, isotropic and non-homogeneous, non-isotropic matter without using (or in the absence of) the mathematical models of the BVPs and the IVPs. These methods are also used for deriving mathematical models for BVPs and IVPs associated with isotropic, homogeneous as well as non-homogeneous, non-isotropic continuous matter. In energy methods when applied to IVPs, one constructs energy functional (<i>I</i>) consisting of kinetic energy, strain energy and the potential energy of loads. The first variation of this energy functional (<em>δI</em>) set to zero is a necessary condition for an extremum of <i>I</i>. In this approach one could use <i>δI</i> = 0 directly in constructing computational processes such as the finite element method or could derive Euler’s equations (differential or partial differential equations) from <i>δI</i> = 0, which is also satisfied by a solution obtained from <i>δI</i> = 0. The Euler’s equations obtained from <i>δI</i> = 0 indeed are the mathematical model associated with the energy functional <i>I</i>. In case of BVPs we follow the same approach except in this case, the energy functional <i>I</i> consists of strain energy and the potential energy of loads. In using the principle of virtual work for BVPs and the IVPs, we can also accomplish the same as described above using energy methods. In this paper we investigate consistency and validity of the mathematical models for isotropic, homogeneous and non-isotropic, non-homogeneous continuous matter for BVPs that are derived using energy functional consisting of strain energy and the potential energy of loads. Similar investigation is also presented for IVPs using energy functional consisting of kinetic energy, strain energy and the potential energy of loads. The computational approaches for BVPs and the IVPs designed using energy functional and principle of virtual work, their consistency and validity are also investigated. Classical continuum mechanics (CCM) principles <i>i.e.</i> conservation and balance laws of CCM with consistent constitutive theories and the elements of calculus of variations are employed in the investigations presented in this paper. 展开更多
关键词 Energy methods Principle of Virtual Work Calculus of Variations euler’s Equation Mathematical Model Classical and Non-Classical Continuum Mechanics
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基于PSO-GRNN和D-S证据理论的电网分区故障诊断 被引量:5
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作者 邹红波 宋璐 +2 位作者 张馨煜 段治丰 宋家乐 《智慧电力》 北大核心 2023年第3期25-30,45,共7页
针对大电网中保护和断路器误动、拒动、信息丢失等不确定的电网故障信息以及现有电网分区方法的不足,提出了基于粒子群优化广义回归神经网络(PSO-GRNN)和D-S证据理论的电网分区故障诊断方法。首先,通过改进图形分割法将大电网划分为相... 针对大电网中保护和断路器误动、拒动、信息丢失等不确定的电网故障信息以及现有电网分区方法的不足,提出了基于粒子群优化广义回归神经网络(PSO-GRNN)和D-S证据理论的电网分区故障诊断方法。首先,通过改进图形分割法将大电网划分为相互重叠的不同区域,降低故障诊断难度。然后在各个区域建立PSOGRNN诊断模块,根据故障警报信息,并行完成各自的故障诊断任务。最后,采用D-S证据理论对相邻区域的重叠区域进行分析,以实现对重叠区域的综合故障诊断。仿真结果表明,该方法能有效识别非重叠区域和重叠区域的故障,容错能力强,诊断准确率高。 展开更多
关键词 电网分区 故障诊断 改进图形分割法 粒子群算法 广义回归神经网络 D-s证据理论
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An Inexact Halley's Method
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作者 闫桂峰 田祥 《Journal of Beijing Institute of Technology》 EI CAS 2005年第3期340-343,共4页
An inexact Halley's method-Halley-PCG(preconditioned conjugate gradient) method is proposed for solving the systems of linear equations for improved Halley method either by Cholesky factorization exactly or by prec... An inexact Halley's method-Halley-PCG(preconditioned conjugate gradient) method is proposed for solving the systems of linear equations for improved Halley method either by Cholesky factorization exactly or by preconditioned conjugate gradient method approximately. The convergence result is given and the efficiency of the method compared to the improved Halley's method is shown. 展开更多
关键词 unconstrained optimization problems improved Halley's method preconditioned conjugate gradient method
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基于无人机点云与改进R_(S)表征法的结构面粗糙度定量分析
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作者 杨泽 李保天 +3 位作者 宋盛渊 秦龙 刘殿泽 黄迪 《哈尔滨工业大学学报》 EI CAS CSCD 北大核心 2023年第11期72-81,共10页
为研究采样尺寸、采样间距对高陡斜坡岩体结构面粗糙度评价结果的影响,选取藏东南某铁路察达车站工点左岸高陡岩质斜坡为研究区,提出采用无人机多角度贴近摄影测量技术获取毫米级点云数据以建立研究区斜坡岩体高精度三维模型,并从中选... 为研究采样尺寸、采样间距对高陡斜坡岩体结构面粗糙度评价结果的影响,选取藏东南某铁路察达车站工点左岸高陡岩质斜坡为研究区,提出采用无人机多角度贴近摄影测量技术获取毫米级点云数据以建立研究区斜坡岩体高精度三维模型,并从中选取典型区域裁剪出带有点云信息的27条面状结构面,使用Delaunay三角化原理对结构面进行网格化重建。基于此,提出一种采用点云拟合平面代替R_(S)表征法中垂直投影平面的新方法,并研究结构面粗糙度在不同采样尺寸、采样间距下的变化规律,结果表明:不同三角剖分方式对R_(S)表征值影响较小;结构面粗糙度具有尺寸效应与间距效应,其粗糙度表征值随结构面尺寸的增加逐渐趋于稳定,随结构面采样间距增大逐渐减小;部分存在尺寸效应的结构面存在“假有效采样尺寸”与“真有效采样尺寸”。在进行粗糙度评价时应确保所得有效采样尺寸为“真有效采样尺寸”。 展开更多
关键词 多角度贴近摄影 结构面粗糙度 改进R_(s)表征法 尺寸效应 间距效应 三角剖分
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A Numerical Study of Several Species Population Models
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作者 Francisco J. Sánchez-Bernabe Maria del Rosario Escalona-Magdaleno 《Journal of Applied Mathematics and Physics》 2023年第12期3943-3952,共10页
This work considers a special case of Lotka-Volterra equations, which means that in the system of two ordinary differential equations, we take the four parameters equal to one. The reason is that we want just to illus... This work considers a special case of Lotka-Volterra equations, which means that in the system of two ordinary differential equations, we take the four parameters equal to one. The reason is that we want just to illustrate the procedure to reduce that system to only one ordinary differential equation, such that we know its analytical solution. This idea will be applied to study the relations between a system of three ordinary differential equations, and a couple of partial differential equations. Lotka-Volterra equations are solved numerically by a fourth-order predictor-corrector method, which is initialized by an improved Euler method with a rather small time step because it is only a second-order algorithm. Then, it is proposed a model with three species, defined by ordinary differential equations. 展开更多
关键词 Lotka-Volterra Equations Adams-Bashfort Predictor Adams-Moulton Corrector improved euler method GeoGebra Matlab
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基于改进的广义S变换求取地层品质因子Q值 被引量:24
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作者 付勋勋 徐峰 +2 位作者 秦启荣 李培 邵晓州 《石油地球物理勘探》 EI CSCD 北大核心 2012年第3期457-461,357-358+518,共5页
地层的品质因子Q值对衡量地震波传播过程中的能量衰减以及地震资料的处理、解释有重要意义。在实际生产中求取品质因子最实用的方法是频谱比法,但传统的频谱比法面临时窗选取等问题。本文利用改进的广义S变换时频特性及与傅里叶谱相联... 地层的品质因子Q值对衡量地震波传播过程中的能量衰减以及地震资料的处理、解释有重要意义。在实际生产中求取品质因子最实用的方法是频谱比法,但传统的频谱比法面临时窗选取等问题。本文利用改进的广义S变换时频特性及与傅里叶谱相联系的特性,提取地层上、下界面对应的瞬时频谱,并通过拟合振幅比与频率的关系得到地层的品质因子Q值。数值模拟及实际资料处理均证明了该方法的有效性。 展开更多
关键词 品质因子Q值 改进的广义s变换 频谱比法
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基于广义S变换地震高分辨率处理方法的改进及在流花11-1油田的应用 被引量:10
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作者 孙雷鸣 万欢 +2 位作者 陈辉 冯全雄 何玉梅 《中国海上油气》 CAS 北大核心 2011年第4期234-237,共4页
相比较早的小波变换和傅氏变换,广义S变换具有更好的时频局部性,但也存在低频信息易损失、弱反射层易丢失等问题。对基于广义S变换的地震高分辨率处理方法进行了改进,提出了新的处理思路。这种基于广义S变换的高分辨率处理技术,在提取... 相比较早的小波变换和傅氏变换,广义S变换具有更好的时频局部性,但也存在低频信息易损失、弱反射层易丢失等问题。对基于广义S变换的地震高分辨率处理方法进行了改进,提出了新的处理思路。这种基于广义S变换的高分辨率处理技术,在提取并补偿高频信号的同时,也对低频信号进行了有效的保持。该项技术在流花11-1油田取得了良好的应用效果。 展开更多
关键词 高分辨率 广义s变换 方法改进 流花11-1油田
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河流分类分级分段及河流形态学研究进展
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作者 董耀华 《水利水电快报》 2024年第9期6-13,共8页
河流分类、河流分级及干流河道分段合称为河流三分(分类·分级·分段);基于河流三要素(流域-水系-干流河道)和河流三分-河流形态学-河流学体系,开展了河流三分理论研究及实践应用、河流形态学再构建以及河流形态定性特性与定量... 河流分类、河流分级及干流河道分段合称为河流三分(分类·分级·分段);基于河流三要素(流域-水系-干流河道)和河流三分-河流形态学-河流学体系,开展了河流三分理论研究及实践应用、河流形态学再构建以及河流形态定性特性与定量因子指标辨识。主要成果结论包括:①优化了独立与非独立河流分类、河流分级Horton法改进、河流5区分段等方法,完善了河流界定拓展、河流平等与分级、干流河道“层次分段”等新理论,总结了世界大江大河及长江河流三分实践应用;②河流形态学研究河流现状及恒常形态,包括以河流三分为基石的河流三要素特性研究和以干流河道平面-剖面-断面形态为核心的河谷-河床-河道形态研究;③定性辨识了河流形态15项殊相特性与共相原则(包括复合流域水系、复杂干流河道等形态特性,干流河道优先、河流湖泊统一、干流河道唯一、侵蚀基面统一等新增原则);④定量辨识了河流形态4类因子指标,双指标3种相关关系(并行-从属-或然)与3类组合模式(物理-化学-生物)以及三因子4类及9种相关模式(均衡线型-瓶颈线型-三角形-金字塔-均分圆-同心圆-同切圆-交叉圆-三角圆)。倡导“河流学-长江学-水科学”学科范式,积极践行“治河·治江·治水”理念。 展开更多
关键词 独立与非独立河流分类 河流分级Horton法改进 河流5区分段法 河流形态学 双指标相关与组合 三因子相关模式 河流三要素(流域-水系-干流河道) 河流学-长江学-水科学
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铬天青S分光光度法测膨化食品中铝 被引量:7
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作者 李世荣 向晓霞 刘仙 《中国卫生检验杂志》 CAS 2008年第8期1533-1534,共2页
目的:探讨铬天青S作显色剂测定膨化食品中铝的方法。方法:样品经消化后,在乙二胺-盐酸缓冲介质存在下,铝与铬天青S和聚乙二醇辛基苯醚及溴代十六烷基吡啶形成稳定蓝色四元体系,在一定浓度范围内,其吸光度与铝含量成正比。结果:在铝... 目的:探讨铬天青S作显色剂测定膨化食品中铝的方法。方法:样品经消化后,在乙二胺-盐酸缓冲介质存在下,铝与铬天青S和聚乙二醇辛基苯醚及溴代十六烷基吡啶形成稳定蓝色四元体系,在一定浓度范围内,其吸光度与铝含量成正比。结果:在铝含量为0~0.1 mg/L的范围内,有良好的线性关系,平均相关系数r=0.9998,回收率在91.0%~95.2%之间,相对标准偏差为1.72%~2.22%。结论:该方法显色灵敏、稳定性好、准确、干扰少,适用于测量膨化食品中的铝。 展开更多
关键词 铬天青s 膨化食品 方法改进
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Hurst指数估计法的比较和研究 被引量:9
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作者 赵彦仲 吴立文 《计算机工程与应用》 CSCD 2014年第16期154-158,共5页
针对时间序列的Hurst指数的估计方法的问题,目前国内外已经提出了R/S,DAF,绝对值法,周期图法等多种方法。但上述方法都会对Hurst指数的估计值产生易误解和不一致的结果。针对这个问题,通过对R/S分析法,小波分析法,迭代估计算法和Whittl... 针对时间序列的Hurst指数的估计方法的问题,目前国内外已经提出了R/S,DAF,绝对值法,周期图法等多种方法。但上述方法都会对Hurst指数的估计值产生易误解和不一致的结果。针对这个问题,通过对R/S分析法,小波分析法,迭代估计算法和Whittle法的描述,进行数值模拟来说明这些方法所得Hurst指数估计值的误差,通过比较能够得出Whittle法是一种具有更高精度和更好稳定性的方法。 展开更多
关键词 分形布朗运动 改进Whittle法 小波分析法 迭代估计法
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