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Numerical Simulation of Oil-Water Two-Phase Flow in Low Permeability Tight Reservoirs Based on Weighted Least Squares Meshless Method
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作者 Xin Liu Kai Yan +3 位作者 Bo Fang Xiaoyu Sun Daqiang Feng Li Yin 《Fluid Dynamics & Materials Processing》 EI 2024年第7期1539-1552,共14页
In response to the complex characteristics of actual low-permeability tight reservoirs,this study develops a meshless-based numerical simulation method for oil-water two-phase flow in these reservoirs,considering comp... In response to the complex characteristics of actual low-permeability tight reservoirs,this study develops a meshless-based numerical simulation method for oil-water two-phase flow in these reservoirs,considering complex boundary shapes.Utilizing radial basis function point interpolation,the method approximates shape functions for unknown functions within the nodal influence domain.The shape functions constructed by the aforementioned meshless interpolation method haveδ-function properties,which facilitate the handling of essential aspects like the controlled bottom-hole flow pressure in horizontal wells.Moreover,the meshless method offers greater flexibility and freedom compared to grid cell discretization,making it simpler to discretize complex geometries.A variational principle for the flow control equation group is introduced using a weighted least squares meshless method,and the pressure distribution is solved implicitly.Example results demonstrate that the computational outcomes of the meshless point cloud model,which has a relatively small degree of freedom,are in close agreement with those of the Discrete Fracture Model(DFM)employing refined grid partitioning,with pressure calculation accuracy exceeding 98.2%.Compared to high-resolution grid-based computational methods,the meshless method can achieve a better balance between computational efficiency and accuracy.Additionally,the impact of fracture half-length on the productivity of horizontal wells is discussed.The results indicate that increasing the fracture half-length is an effective strategy for enhancing production from the perspective of cumulative oil production. 展开更多
关键词 Weighted least squares method meshless method numerical simulation of low permeability tight reservoirs oil-water two-phase flow fracture half-length
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Least square method based on Haar wavelet to solve multi-dimensional stochastic Ito-Volterra integral equations
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作者 JIANG Guo KE Ting DENG Meng-ting 《Applied Mathematics(A Journal of Chinese Universities)》 SCIE CSCD 2023年第4期591-603,共13页
This paper proposes a method combining blue the Haar wavelet and the least square to solve the multi-dimensional stochastic Ito-Volterra integral equation.This approach is to transform stochastic integral equations in... This paper proposes a method combining blue the Haar wavelet and the least square to solve the multi-dimensional stochastic Ito-Volterra integral equation.This approach is to transform stochastic integral equations into a system of algebraic equations.Meanwhile,the error analysis is proven.Finally,the effectiveness of the approach is verified by two numerical examples. 展开更多
关键词 least squares method Haar wavelet Ito-Volterra integral equations integration operational matrix.
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运用Four Square Writing Method促进高中英语读写教学——以“Theme Parks—Fun and More Than Fun”为阅读文本
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作者 李秀连 《教学月刊(中学版)(外语教学)》 2023年第4期56-61,共6页
读写教学可以使学生通过综合性语言实践活动,实现语言能力、文化意识、思维品质和学习能力的融合发展。运用Four Square Writing Method促进高中英语读写教学可以采用引导学生先搭建图示化的阅读文本结构和内容框架,然后内化所学框架,... 读写教学可以使学生通过综合性语言实践活动,实现语言能力、文化意识、思维品质和学习能力的融合发展。运用Four Square Writing Method促进高中英语读写教学可以采用引导学生先搭建图示化的阅读文本结构和内容框架,然后内化所学框架,进而迁移运用所学框架解决实际生活中的新问题这一路径,以培养学生的核心素养。 展开更多
关键词 高中英语读写教学 Four square Writing method 图形框架
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Multi-Branch Fault Line Location Method Based on Time Difference Matrix Fitting
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作者 Hua Leng Silin He +3 位作者 Jian Qiu Feng Liu Xinfei Huang Jiran Zhu 《Energy Engineering》 EI 2024年第1期77-94,共18页
The distribution network exhibits complex structural characteristics,which makes fault localization a challenging task.Especially when a branch of the multi-branch distribution network fails,the traditional multi-bran... The distribution network exhibits complex structural characteristics,which makes fault localization a challenging task.Especially when a branch of the multi-branch distribution network fails,the traditional multi-branch fault location algorithm makes it difficult to meet the demands of high-precision fault localization in the multi-branch distribution network system.In this paper,the multi-branch mainline is decomposed into single branch lines,transforming the complex multi-branch fault location problem into a double-ended fault location problem.Based on the different transmission characteristics of the fault-traveling wave in fault lines and non-fault lines,the endpoint reference time difference matrix S and the fault time difference matrix G were established.The time variation rule of the fault-traveling wave arriving at each endpoint before and after a fault was comprehensively utilized.To realize the fault segment location,the least square method was introduced.It was used to find the first-order fitting relation that satisfies the matching relationship between the corresponding row vector and the first-order function in the two matrices,to realize the fault segment location.Then,the time difference matrix is used to determine the traveling wave velocity,which,combined with the double-ended traveling wave location,enables accurate fault location. 展开更多
关键词 Multi-branch lines distribution network fault location double-ended traveling wave positioning least square method
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A Study of EM Algorithm as an Imputation Method: A Model-Based Simulation Study with Application to a Synthetic Compositional Data
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作者 Yisa Adeniyi Abolade Yichuan Zhao 《Open Journal of Modelling and Simulation》 2024年第2期33-42,共10页
Compositional data, such as relative information, is a crucial aspect of machine learning and other related fields. It is typically recorded as closed data or sums to a constant, like 100%. The statistical linear mode... Compositional data, such as relative information, is a crucial aspect of machine learning and other related fields. It is typically recorded as closed data or sums to a constant, like 100%. The statistical linear model is the most used technique for identifying hidden relationships between underlying random variables of interest. However, data quality is a significant challenge in machine learning, especially when missing data is present. The linear regression model is a commonly used statistical modeling technique used in various applications to find relationships between variables of interest. When estimating linear regression parameters which are useful for things like future prediction and partial effects analysis of independent variables, maximum likelihood estimation (MLE) is the method of choice. However, many datasets contain missing observations, which can lead to costly and time-consuming data recovery. To address this issue, the expectation-maximization (EM) algorithm has been suggested as a solution for situations including missing data. The EM algorithm repeatedly finds the best estimates of parameters in statistical models that depend on variables or data that have not been observed. This is called maximum likelihood or maximum a posteriori (MAP). Using the present estimate as input, the expectation (E) step constructs a log-likelihood function. Finding the parameters that maximize the anticipated log-likelihood, as determined in the E step, is the job of the maximization (M) phase. This study looked at how well the EM algorithm worked on a made-up compositional dataset with missing observations. It used both the robust least square version and ordinary least square regression techniques. The efficacy of the EM algorithm was compared with two alternative imputation techniques, k-Nearest Neighbor (k-NN) and mean imputation (), in terms of Aitchison distances and covariance. 展开更多
关键词 Compositional Data Linear Regression Model Least square method Robust Least square method Synthetic Data Aitchison Distance Maximum Likelihood Estimation Expectation-Maximization Algorithm k-Nearest Neighbor and Mean imputation
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WEIGHTED LEAST SQUARE METHOD FOR S-N CURVE FITTING 被引量:7
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作者 吉凤贤 姚卫星 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 2004年第1期53-57,共5页
An S-N curve fitting approach is proposed based on the weighted least square method, and the weights are inversely proportional to the length of mean confidence intervals of experimental data sets. The assumption coin... An S-N curve fitting approach is proposed based on the weighted least square method, and the weights are inversely proportional to the length of mean confidence intervals of experimental data sets. The assumption coincides with the physical characteristics of the fatigue life scatter. Two examples demonstrate the method. It is shown that the method has better accuracy and reasonableness compared with the usual least square method. 展开更多
关键词 fatigue test S-N curve weighted least square method confidence interval
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GPS short-delay multipath estimation and mitigation based on least square method 被引量:6
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作者 Zhang Shengkang~(1,2),Wang Hongbo~(1,2),Yang Jun~(1,2) & He Leiming~(1,2) 1.Beijing Inst.of Radio Metrology and Measurement,Beijing 100854,P.R.China 2.National Key Laboratory of Metrology and Calibration Technology,Beijing 100854,P.R.China 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2009年第5期954-961,共8页
The GPS multipath signal model is presented, which indicates that the coherent DLL outputs in multipath environment are the convolution between the ideal DLL outputs and the channel responses. So the channel responses... The GPS multipath signal model is presented, which indicates that the coherent DLL outputs in multipath environment are the convolution between the ideal DLL outputs and the channel responses. So the channel responses can be estimated by a least square method using the observed curve of the DLL discriminator. In terms of the estimated multipath channels, two multipath mitigation methods are discussed, which are equalization filtering and multipath subtracting, respectively. It is shown, by computer simulation, that the least square method has a good performance in channels estimation and the multipath errors can be mitigated almost completely by either of the methods. However, the multipath subtracting method has relative small remnant errors than equalization filtering. 展开更多
关键词 global positioning system short-delay least square method multipath mitigation.
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Parameter identification and pressure control of dynamic system in shield tunneling using least squares method 被引量:10
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作者 LI Shou-ju CAO Li-juan +1 位作者 SHANGGUAN Zi-chang LIU Bo 《Journal of Coal Science & Engineering(China)》 2010年第3期256-261,共6页
An estimation approach using least squares method was presented for identificationof model parameters of pressure control in shield tunneling.The state equation ofthe pressure control system for shield tunneling was a... An estimation approach using least squares method was presented for identificationof model parameters of pressure control in shield tunneling.The state equation ofthe pressure control system for shield tunneling was analytically derived based on themass equilibrium principle that the entry mass of the pressure chamber from cutting headwas equal to excluding mass from the screw conveyor.The randomly observed noise wasnumerically simulated and mixed to simulated observation values of system responses.The numerical simulation shows that the state equation of the pressure control system forshield tunneling is reasonable and the proposed estimation approach is effective even ifthe random observation noise exists.The robustness of the controlling procedure is validatedby numerical simulation results. 展开更多
关键词 parameter identification least squares method state equation shield tunneling
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Online Detection of Broken Rotor Bar Fault in Induction Motors by Combining Estimation of Signal Parameters via Min-norm Algorithm and Least Square Method 被引量:4
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作者 Pan-Pan Wang Qiang Yu +1 位作者 Yong-Jun Hu Chang-Xin Miao 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2017年第6期1285-1295,共11页
Current research in broken rotor bar (BRB) fault detection in induction motors is primarily focused on a high-frequency resolution analysis of the stator current. Compared with a discrete Fourier transformation, the... Current research in broken rotor bar (BRB) fault detection in induction motors is primarily focused on a high-frequency resolution analysis of the stator current. Compared with a discrete Fourier transformation, the parametric spectrum estimation technique has a higher frequency accuracy and resolution. However, the existing detection methods based on parametric spectrum estima- tion cannot realize online detection, owing to the large computational cost. To improve the efficiency of BRB fault detection, a new detection method based on the min-norm algorithm and least square estimation is proposed in this paper. First, the stator current is filtered using a band-pass filter and divided into short overlapped data windows. The min-norm algorithm is then applied to determine the fre- quencies of the fundamental and fault characteristic com- ponents with each overlapped data window. Next, based on the frequency values obtained, a model of the fault current signal is constructed. Subsequently, a linear least squares problem solved through singular value decomposition is designed to estimate the amplitudes and phases of the related components. Finally, the proposed method is applied to a simulated current and an actual motor, the results of which indicate that, not only parametric spectrum estimation technique. 展开更多
关键词 Fault detection Broken rotor bars Min-norm Least squares method Induction motors
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ADAPTIVE FUSION ALGORITHMS BASED ON WEIGHTED LEAST SQUARE METHOD 被引量:9
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作者 SONG Kaichen NIE Xili 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2006年第3期451-454,共4页
Weighted fusion algorithms, which can be applied in the area of multi-sensor data fusion, are advanced based on weighted least square method. A weighted fusion algorithm, in which the relationship between weight coeff... Weighted fusion algorithms, which can be applied in the area of multi-sensor data fusion, are advanced based on weighted least square method. A weighted fusion algorithm, in which the relationship between weight coefficients and measurement noise is established, is proposed by giving attention to the correlation of measurement noise. Then a simplified weighted fusion algorithm is deduced on the assumption that measurement noise is uncorrelated. In addition, an algorithm, which can adjust the weight coefficients in the simplified algorithm by making estimations of measurement noise from measurements, is presented. It is proved by emulation and experiment that the precision performance of the multi-sensor system based on these algorithms is better than that of the multi-sensor system based on other algorithms. 展开更多
关键词 Weighted least square method Data fusion Measurement noise Correlation
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Assessing dynamic response of multispan viscoelastic thin beams under a moving mass via generalized moving least square method 被引量:3
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作者 Keivan Kiani Ali Nikkhoo Bahman Mehri 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2010年第5期721-733,共13页
Dynamic response of multispan viscoelastic thin beams subjected to a moving mass is studied by an efficient numerical method in some detail. To this end, the unknown parameters of the problem are discretized in spatia... Dynamic response of multispan viscoelastic thin beams subjected to a moving mass is studied by an efficient numerical method in some detail. To this end, the unknown parameters of the problem are discretized in spatial domain using generalized moving least square method (GMLSM) and then, discrete equations of motion based on Lagrange's equation are obtained. Maximum deflection and bending moments are considered as the important design parameters. The design parameter spectra in terms of mass weight and velocity of the moving mass are presented for multispan viscoelastic beams as well as various values of relaxation rate and beam span number. A reasonable good agreement is achieved between the results of the proposed solution and those obtained by other researchers. The results indicate that, although the load inertia effects in beams with higher span number would be intensified for higher levels of moving mass velocity, the maximum values of design parameters would increase either. Moreover, the possibility of mass separation is shown to be more critical as the span number of the beam increases. This fact also violates the linear relation between the mass weight of the moving load and the associated design parameters, especially for high moving mass velocities. However, as the relaxation rate of the beam material increases, the load inertia effects as well as the possibility of moving mass separation reduces. 展开更多
关键词 Moving mass-beam interaction - Multispan viscoelastic beam Euler-Bernoulli beam Generalized moving least square method (GMLSM)
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The least square particle finite element method for simulating large amplitude sloshing flows 被引量:2
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作者 Bo Tang Junfeng Li Tianshu Wang 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2008年第3期317-323,共7页
Large amplitude sloshing in tanks is simulated by the least square particle finite element method (LSPFEM) in this paper. The least square finite element method (LSFEM) is employed to spatially discrete the Navier... Large amplitude sloshing in tanks is simulated by the least square particle finite element method (LSPFEM) in this paper. The least square finite element method (LSFEM) is employed to spatially discrete the Navier-Stokes equations, and to avoid the stabilization issues due to the incompressibility condition for equal-order interpolation of the velocity and the pressure, as usually used in Galerkin method to satisfy the well-known LBB condition. The LSPFEM also uses the Lagrangian description to model the motion of nodes (particles). A mesh which connects these nodes is constructed by a triangulation algorithm to avoid the mesh distortion. A quasi a-shapes algorithm is used to identify the free surface boundary. The nodes are viewed as particles which can freely move and even separate from the main fluid domain. Finally this method is used to study the large amplitude sloshing evolution in two dimensional tanks. The results are compared with those obtained by Flow-3d with good agreement. 展开更多
关键词 Incompressible fluid Least square finiteelement method Lagrangian description Boundaryrecognition COLLAPSE IMPACT
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Calculation of Significant Wave Height Using the Linear Mean Square Estimation Method 被引量:2
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作者 GAO Yangyang YU Dingyong +1 位作者 LI Cuilin XU Delun 《Journal of Ocean University of China》 SCIE CAS 2010年第4期327-332,共6页
Significant wave height is an important criterion in designing coastal and offshore structures.Based on the orthogonality principle, the linear mean square estimation method is applied to calculate significant wave he... Significant wave height is an important criterion in designing coastal and offshore structures.Based on the orthogonality principle, the linear mean square estimation method is applied to calculate significant wave height in this paper.Twenty-eight-year time series of wave data collected from three ocean buoys near San Francisco along the California coast are analyzed.It is proved theoretically that the computation error will be reduced by using as many measured data as possible for the calculation of significant wave height.Measured significant wave height at one buoy location is compared with the calculated value based on the data from two other adjacent buoys.The results indicate that the linear mean square estimation method can be well applied to the calculation and prediction of significant wave height in coastal regions. 展开更多
关键词 significant wave height linear mean square estimation method orthogonality principle
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Application of neural network model coupling with the partial least-squares method for forecasting watre yield of mine 被引量:2
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作者 陈南祥 曹连海 黄强 《Journal of Coal Science & Engineering(China)》 2005年第1期40-43,共4页
Scientific forecasting water yield of mine is of great significance to the safety production of mine and the colligated using of water resources. The paper established the forecasting model for water yield of mine, co... Scientific forecasting water yield of mine is of great significance to the safety production of mine and the colligated using of water resources. The paper established the forecasting model for water yield of mine, combining neural network with the partial least square method. Dealt with independent variables by the partial least square method, it can not only solve the relationship between independent variables but also reduce the input dimensions in neural network model, and then use the neural network which can solve the non-linear problem better. The result of an example shows that the prediction has higher precision in forecasting and fitting. 展开更多
关键词 water yield of mine partial least square method neural network forecasting model
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Calculation of stratum surface principal curvature based on a moving least square method 被引量:2
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作者 LI Guo-qing MENG Zhao-ping +4 位作者 MA Feng-shan ZHAO Hai-jun DING De-min LIU Qin WANG Cheng 《Journal of China University of Mining and Technology》 EI 2008年第1期59-63,共5页
With the east section of the Changji sag Zhunger Basin as a case study, both a principal curvature method and a moving least square method are elaborated. The moving least square method is introduced, for the first ti... With the east section of the Changji sag Zhunger Basin as a case study, both a principal curvature method and a moving least square method are elaborated. The moving least square method is introduced, for the first time, to fit a stratum surface. The results show that, using the same-degree base function, compared with a traditional least square method, the moving least square method can produce lower fitting errors, the fitting surface can describe the morphological characteristics of stratum surfaces more accurately and the principal curvature values vary within a wide range and may be more suitable for the prediction of the distribution of structural fractures. The moving least square method could be useful in curved surface fitting and stratum curvature analysis. 展开更多
关键词 principal curvatures moving least square method surface fitting structural fractures
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Preconditioned iterative methods for solving weighted linear least squares problems 被引量:2
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作者 沈海龙 邵新慧 张铁 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2012年第3期375-384,共10页
A class of preconditioned iterative methods, i.e., preconditioned generalized accelerated overrelaxation (GAOR) methods, is proposed to solve linear systems based on a class of weighted linear least squares problems... A class of preconditioned iterative methods, i.e., preconditioned generalized accelerated overrelaxation (GAOR) methods, is proposed to solve linear systems based on a class of weighted linear least squares problems. The convergence and comparison results are obtained. The comparison results show that the convergence rate of the preconditioned iterative methods is better than that of the original methods. Furthermore, the effectiveness of the proposed methods is shown in the numerical experiment. 展开更多
关键词 PRECONDITIONER generalized accelerated overrelaxation (GAOR) method weighted linear least squares problem CONVERGENCE
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Prediction of Logistics Demand via Least Square Method and Multi-Layer Perceptron 被引量:1
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作者 WEI Leqin ZHANG Anguo 《Journal of Donghua University(English Edition)》 EI CAS 2020年第6期526-533,共8页
To implement the prediction of the logistics demand capacity of a certain region,a comprehensive index system is constructed,which is composed of freight volume and other eight relevant economic indices,such as gross ... To implement the prediction of the logistics demand capacity of a certain region,a comprehensive index system is constructed,which is composed of freight volume and other eight relevant economic indices,such as gross domestic product(GDP),consumer price index(CPI),total import and export volume,port's cargo throughput,total retail sales of consumer goods,total fixed asset investment,highway mileage,and resident population,to form the foundation for the model calculation.Based on the least square method(LSM)to fit the parameters,the study obtains an accurate mathematical model and predicts the changes of each index in the next five years.Using artificial intelligence software,the research establishes the logistics demand model of multi-layer perceptron(MLP)neural network,makes an empirical analysis on the logistics demand of Quanzhou City,and predicts its logistics demand in the next five years,which provides some references for formulating logistics planning and development strategy. 展开更多
关键词 logistics demand least square method(LSM) multi-layer perceptron(MLP) PREDICTION strategic planning
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Recursion Least Square Method to Study the Fault Diagnosis and Its Model of Hydraulic Equipment 被引量:2
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作者 Hu Guoqing Luo Renfei(Department of Mechanical and Electrical Engineering,Xiamen University, 361005, Xiamen, Fujian, P.R.ChinaEmail: gqhu@jingxian.xmu.edu.cn) 《International Journal of Plant Engineering and Management》 1999年第1期383-390,共8页
In this paper establishing model of the fault diagnosis of hydraulic equipment isdescribed in details. It also studies the advantage of the recursion least square method. When theLSM is used in compuring the fault of... In this paper establishing model of the fault diagnosis of hydraulic equipment isdescribed in details. It also studies the advantage of the recursion least square method. When theLSM is used in compuring the fault of hydraulic equipment, not only does it save the computerCPU-time and memory, but it also has a high computation speed and,makes it easy to identifythe estimation parameters. 展开更多
关键词 medel FAULT hydraulic equipment recursion least square method.
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Galerkin-Petrov least squares mixed element method for stationary incompressible magnetohydrodynamics
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作者 罗振东 毛允魁 朱江 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2007年第3期395-404,共10页
The Galerkin-Petrov least squares method is combined with the mixed finite element method to deal with the stationary, incompressible magnetohydrodynamics system of equations with viscosity. A Galerkin-Petrov least sq... The Galerkin-Petrov least squares method is combined with the mixed finite element method to deal with the stationary, incompressible magnetohydrodynamics system of equations with viscosity. A Galerkin-Petrov least squares mixed finite element format for the stationary incompressible magnetohydrodynamics equations is presented. And the existence and error estimates of its solution are derived. Through this method, the combination among the mixed finite element spaces does not demand the discrete Babuska-Brezzi stability conditions so that the mixed finite element spaces could be chosen arbitrartily and the error estimates with optimal order could be obtained. 展开更多
关键词 equation of magnetohydrodynamics mixed element method GalerkinPetrov least squares method error estimate
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A NONLINEAR GALERKIN/PETROV-LEAST SQUARES MIXED ELEMENT METHOD FOR THE STATIONARY NAVIER-STOKES EQUATIONS
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作者 罗振东 朱江 王会军 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2002年第7期783-793,共11页
A nonlinear Galerkin/Petrov-least squares mixed element (NGPLSME) method for the stationary Navier-Stokes equations is presented and analyzed. The scheme is that Petrov-least squares forms of residuals are added to th... A nonlinear Galerkin/Petrov-least squares mixed element (NGPLSME) method for the stationary Navier-Stokes equations is presented and analyzed. The scheme is that Petrov-least squares forms of residuals are added to the nonlinear Galerkin mixed element method so that it is stable for any combination of discrete velocity and pressure spaces without requiring the Babu*lka-Brezzi stability condition. The existence, uniqueness and convergence (at optimal rate) of the NGPLSME solution is proved in the case of sufficient viscosity (or small data). 展开更多
关键词 Navier-Stokes equation nonlinear Galerkin mixed element method Petrov-least squares method error estimate
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