Articles de revues : « Semianalytical technique »

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Murthy, Durbha V., et Krishna Rao V. Kaza. « Semianalytical technique for sensitivity analysis of unsteady aerodynamic computations ». Journal of Aircraft 28, n^o 8 (août 1991) : 481–88. http://dx.doi.org/10.2514/3.46052.

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Haran, Bala S., et Ralph E. White. « A semianalytical technique for solving nonlinear partial differential equations ». Computer Applications in Engineering Education 4, n^o 3 (1996) : 229–40. http://dx.doi.org/10.1002/(sici)1099-0542(1996)4:3<229 ::aid-cae5>3.0.co;2-f.

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Hatten, Noble, et Ryan P. Russell. « Semianalytical Technique for Six-Degree-of-Freedom Space Object Propagation ». Journal of Guidance, Control, and Dynamics 42, n^o 2 (février 2019) : 217–28. http://dx.doi.org/10.2514/1.g003706.

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Porter, D. G., et M. J. Donahue. « Precession axis modification to a semianalytical Landau–Lifshitz solution technique ». Journal of Applied Physics 103, n^o 7 (avril 2008) : 07D920. http://dx.doi.org/10.1063/1.2838461.

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Fathy, A. E., V. A. Pendrick, B. D. Geller, S. M. Perlow, E. S. Tormey, A. Prabhu et S. Tani. « An innovative semianalytical technique for ceramic evaluation at microwave frequencies ». IEEE Transactions on Microwave Theory and Techniques 50, n^o 10 (octobre 2002) : 2247–52. http://dx.doi.org/10.1109/tmtt.2002.803438.

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Peng, Jian-She, Yan Liu et Jie Yang. « A Semianalytical Method for Nonlinear Vibration of Euler-Bernoulli Beams with General Boundary Conditions ». Mathematical Problems in Engineering 2010 (2010) : 1–17. http://dx.doi.org/10.1155/2010/591786.

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This paper presents a new semianalytical approach for geometrically nonlinear vibration analysis of Euler-Bernoulli beams with different boundary conditions. The method makes use of Linstedt-Poincaré perturbation technique to transform the nonlinear governing equations into a linear differential equation system, whose solutions are then sought through the use of differential quadrature approximation in space domain and an analytical series expansion in time domain. Validation of the present method is conducted in numerical examples through direct comparisons with existing solutions, showing that the proposed semianalytical method has excellent convergence and can give very accurate results at a long time interval.

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Hayashi, Takahiro, Koichiro Kawashima, Zongqi Sun et Joseph L. Rose. « Guided Wave Propagation Mechanics Across a Pipe Elbow ». Journal of Pressure Vessel Technology 127, n^o 3 (24 janvier 2005) : 322–27. http://dx.doi.org/10.1115/1.1990210.

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Wave propagation across a pipe elbow region is complex. Subsequent reflected and transmitted waves are largely deformed due to mode conversions at the elbow. This prevents us to date from applying guided waves to the nondestructive evaluation of meandering pipeworks. Since theoretical development of guided wave propagation in a pipe is difficult, numerical modeling techniques are useful. We have introduced a semianalytical finite element method, a special modeling technique for guided wave propagation, because ordinary finite element methods require extremely long computational times and memory for such a long-range guided wave calculation. In this study, the semianalytical finite element method for curved pipes is developed. A curved cylindrical coordinate system is used for the curved pipe region, where a curved center axis of the pipe elbow region is an axis (z′ axis) of the coordinate system, instead of the straight axis (z axis) of the cylindrical coordinate system. Guided waves in the z′ direction are described as a superposition of orthogonal functions. The calculation region is divided only in the thickness and circumferential directions. Using this calculation technique, echoes from the back wall beyond up to four elbows are discussed.

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Iqbal, Javed, Khurram Shabbir et Liliana Guran. « Semianalytical Solutions of Some Nonlinear-Time Fractional Models Using Variational Iteration Laplace Transform Method ». Journal of Function Spaces 2021 (9 novembre 2021) : 1–9. http://dx.doi.org/10.1155/2021/8345682.

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In this work, we combined two techniques, the variational iteration technique and the Laplace transform method, in order to solve some nonlinear-time fractional partial differential equations. Although the exact solutions may exist, we introduced the technique VITM that approximates the solutions that are difficult to find. Even a single iteration best approximates the exact solutions. The fractional derivatives being used are in the Caputo-Fabrizio sense. The reliability and efficiency of this newly introduced method is discussed in details from its numerical results and their graphical approximations. Moreover, possible consequences of these results as an application of fixed-point theorem are placed before the experts as an open problem.

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Lu, Minhua, Shuai Huang, Xianglong Yang, Lei Yang et Rui Mao. « Semianalytical Solution for the Deformation of an Elastic Layer under an Axisymmetrically Distributed Power-Form Load : Application to Fluid-Jet-Induced Indentation of Biological Soft Tissues ». BioMed Research International 2017 (2017) : 1–10. http://dx.doi.org/10.1155/2017/9842037.

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Fluid-jet-based indentation is used as a noncontact excitation technique by systems measuring the mechanical properties of soft tissues. However, the application of these devices has been hindered by the lack of theoretical solutions. This study developed a mathematical model for testing the indentation induced by a fluid jet and determined a semianalytical solution. The soft tissue was modeled as an elastic layer bonded to a rigid base. The pressure of the fluid jet impinging on the soft tissue was assumed to have a power-form function. The semianalytical solution was verified in detail using finite-element modeling, with excellent agreement being achieved. The effects of several parameters on the solution behaviors are reported, and a method for applying the solution to determine the mechanical properties of soft tissues is suggested.

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Ali, Zeeshan, Shayan Naseri Nia, Faranak Rabiei, Kamal Shah et Ming Kwang Tan. « A Semianalytical Approach to the Solution of Time-Fractional Navier-Stokes Equation ». Advances in Mathematical Physics 2021 (16 juillet 2021) : 1–13. http://dx.doi.org/10.1155/2021/5547804.

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In this manuscript, a semianalytical solution of the time-fractional Navier-Stokes equation under Caputo fractional derivatives using Optimal Homotopy Asymptotic Method (OHAM) is proposed. The above-mentioned technique produces an accurate approximation of the desired solutions and hence is known as the semianalytical approach. The main advantage of OHAM is that it does not require any small perturbations, linearization, or discretization and many reductions of the computations. Here, the proposed approach’s reliability and efficiency are demonstrated by two applications of one-dimensional motion of a viscous fluid in a tube governed by the flow field by converting them to time-fractional Navier-Stokes equations in cylindrical coordinates using fractional derivatives in the sense of Caputo. For the first problem, OHAM provides the exact solution, and for the second problem, it performs a highly accurate numerical approximation of the solution compare with the exact solution. The presented simulation results of OHAM comparison with analytical and numerical approaches reveal that the method is an efficient technique to simulate the solution of time-fractional types of Navier-Stokes equation.

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Roy Choudhury, Raja, Arundhati Roy Choudhury et Mrinal Kanti Ghose. « Splice Loss of Graded-Index Fibers : Accurate Semianalytical Descriptions Using Nelder-Mead Nonlinear Unconstrained Optimization with Three-Parameter Fundamental Modal Field ». Advances in Optical Technologies 2013 (8 juillet 2013) : 1–8. http://dx.doi.org/10.1155/2013/168923.

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A faster and accurate semianalytical formulation with a robust optimization solution for estimating the splice loss of graded-index fibers has been proposed. The semianalytical optimization of modal parameters has been carried out by Nelder-Mead method of nonlinear unconstrained minimization suitable for functions which are uncertain, noisy, or even discontinuous. Instead of normally used Gaussian function, as the trial field for the fundamental mode of graded-index optical fiber a novel sinc function with exponentially and R-3/2 (R is the normalized radius of the optical fiber) decaying trailing edge has been used. Due to inclusion of three parameters in the optimization of fundamental modal solution and application of an efficient optimization technique with simple analytical expressions for various modal parameters, the results are found to be accurate and computationally easier to find than the standard numerical method solution.

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Malik, Moinuddin, et Charles W. Bert. « Differential Quadrature Analysis of Free Vibration of Symmetric Cross-Ply Laminates with Shear Deformation and Rotatory Inertia ». Shock and Vibration 2, n^o 4 (1995) : 321–38. http://dx.doi.org/10.1155/1995/703928.

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In the present work, laminates having two opposite edges simply supported are considered. The boundary conditions at the other two opposite edges may be general, and between these two edges, the thickness of the plate may be nonuniform. The theory used for the vibration analysis of such laminates includes shear deformation and rotatory inertia. The solution approach of the problem is semianalytical. By using the trigonometric functions describing the mode shapes between the simply supported edges, the governing plate equations are reduced to ordinary differential equations. The solution of the reduced equations is then sought by the differential quadrature method. The results reported in this article serve two objectives of the present investigations. One, it is demonstrated that the proposed semianalytical quadrature method offers a numerically accurate and computationally efficient technique for the title problem. Two, the relative effects of shear deformation and rotatory inertia are analyzed in a quantitative manner.

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Fukagawa, Hiroshi. « A framework for the evaluation of inflow control effects using a semianalytical technique ». Journal of the Japanese Association for Petroleum Technology 73, n^o 6 (2008) : 507–16. http://dx.doi.org/10.3720/japt.73.507.

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Shah, Nehad Ali, Mounirah Areshi, Jae Dong Chung et Kamsing Nonlaopon. « The New Semianalytical Technique for the Solution of Fractional-Order Navier-Stokes Equation ». Journal of Function Spaces 2021 (20 avril 2021) : 1–13. http://dx.doi.org/10.1155/2021/5588601.

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In this paper, we introduce a modified method which is constructed by mixing the residual power series method and the Elzaki transformation. Precisely, we provide the details of implementing the suggested technique to investigate the fractional-order nonlinear models. Second, we test the efficiency and the validity of the technique on the fractional-order Navier-Stokes models. Then, we apply this new method to analyze the fractional-order nonlinear system of Navier-Stokes models. Finally, we provide 3-D graphical plots to support the impact of the fractional derivative acting on the behavior of the obtained profile solutions to the suggested models.

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Pérez, Iván, Juan Félix San-Juan, Montserrat San-Martín et Luis María López-Ochoa. « Application of Computational Intelligence in Order to Develop Hybrid Orbit Propagation Methods ». Mathematical Problems in Engineering 2013 (2013) : 1–11. http://dx.doi.org/10.1155/2013/631628.

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We present a new approach in astrodynamics and celestial mechanics fields, calledhybrid perturbation theory. A hybrid perturbation theory combines anintegrating technique, general perturbation theory or special perturbation theory or semianalytical method, with aforecasting technique, statistical time series model or computational intelligence method. This combination permits an increase in the accuracy of the integrating technique, through the modeling of higher-order terms and other external forces not considered in the integrating technique. In this paper, neural networks have been used as time series forecasters in order to help two economic general perturbation theories describe the motion of an orbiter only perturbed by the Earth’s oblateness.

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Shah, Nehad Ali, S. Saleem, Ali Akgül, Kamsing Nonlaopon et Jae Dong Chung. « Numerical Analysis of Time-Fractional Diffusion Equations via a Novel Approach ». Journal of Function Spaces 2021 (26 mai 2021) : 1–12. http://dx.doi.org/10.1155/2021/9945364.

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The aim of this paper is a new semianalytical technique called the variational iteration transform method for solving fractional-order diffusion equations. In the variational iteration technique, identifying of the Lagrange multiplier is an essential rule, and variational theory is commonly used for this purpose. The current technique has the edge over other methods as it does not need extra parameters and polynomials. The validity of the proposed method is verified by considering some numerical problems. The solution achieved has shown that the better accuracy of the proposed technique. This paper proposes a simpler method to calculate the multiplier using the Shehu transformation, making a valuable technique to researchers dealing with various linear and nonlinear problems.

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Makukula, Zodwa G., Precious Sibanda et Sandile S. Motsa. « A Novel Numerical Technique for Two-Dimensional Laminar Flow between Two Moving Porous Walls ». Mathematical Problems in Engineering 2010 (2010) : 1–15. http://dx.doi.org/10.1155/2010/528956.

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We investigate the steady two-dimensional flow of a viscous incompressible fluid in a rectangular domain that is bounded by two permeable surfaces. The governing fourth-order nonlinear differential equation is solved by applying the spectral-homotopy analysis method and a novel successive linearisation method. Semianalytical results are obtained and the convergence rate of the solution series was compared with numerical approximations and with earlier results where the homotopy analysis and homotopy perturbation methods were used. We show that both the spectral-homotopy analysis method and successive linearisation method are computationally efficient and accurate in finding solutions of nonlinear boundary value problems.

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Alshammari, Mohammad, Wael W. Mohammed et Mohammed Yar. « Novel Analysis of Fuzzy Fractional Klein-Gordon Model via Semianalytical Method ». Journal of Function Spaces 2022 (16 mai 2022) : 1–9. http://dx.doi.org/10.1155/2022/4020269.

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The current article discusses the new fuzzy iterative transform method, a hybrid methodology based on fuzzy logic and an iterative transformation technique. We demonstrate the consistency of our technique by employing the Caputo derivative under generalized Hukuhara differentiability to construct fractional fuzzy Klein-Gordon equations with the initial fuzzy condition. The series produced result was calculated and compared to the exact result’s recommended equations. Two problems were used to verify our method, with the results approximated in fuzzy form. The upper and lower half of the fuzzy results were approximated in each of the two examples using two distinct fractional orders between zero and one. Because it globalizes the dynamical behavior of the specified equation, it produces all forms of fuzzy results at any fractional order between 0 and 1. Since fuzzy numbers offer their results in a fuzzy form with lower and upper branches, the unknown amount also adds fuzziness. It is crucial to emphasize that the suggested fuzziness method is intended to demonstrate the efficiency and superiority of numerical solutions to nonlinear fractional fuzzy partial differential equations found in complex and physical structures.

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Rowe, R. Kerry, et John R. Booker. « A finite layer technique for modelling complex landfill history ». Canadian Geotechnical Journal 32, n^o 4 (1 août 1995) : 660–76. http://dx.doi.org/10.1139/t95-066.

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A semianalytical (finite layer) technique for modelling contaminant transport from a landfill for relatively complex conditions is presented. The theory allows consideration of multiple units such as secondary leachate collection systems, hydraulic control layers, or aquifers, which can be used to remove contaminant from below the landfill. The theory allows consideration of time-varying properties of the system (e.g., shutdown or failure of the primary and (or) secondary leachate collection systems after a specified period of time). It also allows consideration of complex source concentration histories with time, including the increase in concentration with time, constant source concentration for a period of time, and decrease in concentration as mass is removed from the system. The application of the technique is illustrated with an example. Key words : contaminant impact, analysis, landfill design, clay, fractures, diffusion, failure, groundwater.

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Nawaz, R., S. Islam, I. A. Shah, M. Idrees et H. Ullah. « Optimal Homotopy Asymptotic Method to Nonlinear Damped Generalized Regularized Long-Wave Equation ». Mathematical Problems in Engineering 2013 (2013) : 1–13. http://dx.doi.org/10.1155/2013/503137.

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A new semianalytical technique optimal homology asymptotic method (OHAM) is introduced for deriving approximate solution of the homogeneous and nonhomogeneous nonlinear Damped Generalized Regularized Long-Wave (DGRLW) equation. We tested numerical examples designed to confine the features of the proposed scheme. We drew 3D and 2D images of the DGRLW equations and the results are compared with that of variational iteration method (VIM). Results reveal that OHAM is operative and very easy to use.

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Ullah, Hakeem, Mehreen Fiza, Muhammad Asif Zahoor Raja, Imran Khan, Muhammad Shoaib et Seham M. Al-Mekhlafi. « Intelligent Computing of Levenberg-Marquard Technique Backpropagation Neural Networks for Numerical Treatment of Squeezing Nanofluid Flow between Two Circular Plates ». Mathematical Problems in Engineering 2022 (19 août 2022) : 1–11. http://dx.doi.org/10.1155/2022/9451091.

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This study presents new techniques based on the artificial intelligence neural network with Levenberg-Marquardt Scheme with backpropagation (ANN-LMS). The boundary value problem BVP is obtained from the governing equations of the flow model. Along with ANN-LMS, the semianalytical method namely the optimal homotopy analysis method (OHAM) is used for validating the results. ANN-LMS optimized the absolute error and increased the accuracy of the solution. The effect of physical parameters is discussed with the help of plots and tables.

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Hayashi, Takahiro, Koichiro Kawashima, Zongqi Sun et Joseph L. Rose. « Guided Wave Focusing Mechanics in Pipe ». Journal of Pressure Vessel Technology 127, n^o 3 (24 janvier 2005) : 317–21. http://dx.doi.org/10.1115/1.1990209.

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Guided waves can be used in pipe inspection over long distances. Presented in this paper is a beam focusing technique to improve the S∕N ratio of the reflection from a tiny defect. Focusing is accomplished by using nonaxisymmetric waveforms and subsequent time delayed superposition at a specific point in a pipe. A semianalytical finite element method is used to present wave structure in the pipe. Focusing potential is also studied with various modes and frequencies.

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El-Sayad, Mohamed A., et Ahmed M. Farag. « Semi-Analytical Solution Based on Strip Method for Buckling and Vibration of Isotropic Plate ». Journal of Applied Mathematics 2013 (2013) : 1–10. http://dx.doi.org/10.1155/2013/796274.

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The present paper achieves a semianalytical solution for the buckling and vibration of isotropic rectangular plates. Two opposite edges of plate are simply supported and others are either free, simply supported, or clamped restrained against rotation. The general Levy type solution and strip technique are employed with transition matrix method to develop a semianalytical approach for analyzing the buckling and vibration of rectangular plates. The present analytical approach depends on reducing the strips number of the decomposed domain of plate without escaping the results accuracy. For this target, the transition matrix is expressed analytically as a series with sufficient truncation numbers. The effect of the uni-axial and bi-axial in-plane forces on the natural frequency parameters and mode shapes of restrained plate is studied. The critical buckling of rectangular plate under compressive in-plane forces is also examined. Analytical results of buckling loads and vibration frequencies are obtained for various types of boundary conditions. The influences of the aspect ratios, buckling forces, and coefficients of restraint on the buckling and vibration behavior of rectangular plates are investigated. The presented analytical results may serve as benchmark solutions for such plates. The convergence and efficiency of the present technique are demonstrated by several numerical examples compared with those available in the published literature. The results show fast convergence and stability in good agreement with compressions.

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Hu, Lanxiao, Huazhou Andy Li, Tayfun Babadagli et Majid Ahmadloo. « A Semianalytical Model for Simulating Combined Electromagnetic Heating and Solvent-Assisted Gravity Drainage ». SPE Journal 23, n^o 04 (12 mars 2018) : 1248–70. http://dx.doi.org/10.2118/189979-pa.

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Summary Solvent/thermal hybrid methods have been proposed recently to enhance heavy-oil recovery and to overcome the shortcomings that are encountered when either method is solely applied. One of the methods for this hybridization is to combine electromagnetic (EM) heating and solvent injection to facilitate heavy-oil production by gravity drainage. This approach has several advantages including reduced CO2 emissions, decreased water consumption, and appropriateness for water-hostile reservoirs. We are currently lacking any mathematical model for better understanding, designing, and optimizing this hybrid technique, which is partly attributed to this technique still being in its infancy. We propose a semianalytical model to predict the oil-flow rate resulting from the combined EM heating and solvent-assisted gravity drainage. The model first calculates the temperature distribution within the EM-excited zone caused by the radiation-dominated EM heating. Using different attenuation coefficients within and beyond the vapor chamber, the model can properly describe the corresponding temperature responses in these regions. Next, an average temperature of the chamber edge contributed by EM heating is used to estimate the temperature-dependent properties, such as vapor/liquid equilibrium ratios (K-values), heavy-oil/solvent-mixture viscosity, and solvent diffusivity. Subsequently, a 1D diffusion equation is used to calculate the solvent-concentration distribution ahead of the chamber edge. Eventually, the oil-flow rate is evaluated with the calculated temperature and solvent distributions ahead of the chamber edge. The proposed model is validated against the experimental results obtained in our previous study, and the predicted oil-flow rate agrees reasonably well with the experimental data. The proposed model can efficiently predict the oil-flow rate of this hybrid process. We conduct sensitivity analyses to examine the effect of major influential factors on the performance of this hybrid technique, including EM heating powers, solvent types, solvent-injection pressures, and initial reservoir temperatures. The modeling results demonstrate that a higher EM heating power, a heavier solvent, and a higher solvent-injection pressure could accelerate the oil-recovery rate, but tend to lower the net present value (NPV) and increase the energy consumption. In summary, the newly proposed model provides an efficient tool to understand, design, and optimize the combined technique of EM heating and solvent-assisted gravity drainage.

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Aljahdaly, Noufe H., Muhammad Naeem et Noorolhuda Wyal. « Analysis of Fuzzy Kuramoto-Sivashinsky Equations under a Generalized Fuzzy Fractional Derivative Operator ». Journal of Function Spaces 2022 (7 juin 2022) : 1–11. http://dx.doi.org/10.1155/2022/9517158.

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This paper evaluates a semianalytical strategy combined with a novel fuzzy integral transformation and an iterative method inside the fuzziness concept known as the new iterative transform method. Additionally, we apply the abovementioned technique to the fractional fuzzy Kuramoto-Sivashinsky equations with g H -differentiability by employing various initial conditions. Numerous algebraic properties of the fuzzy fractional derivative Atangana-Baleanu operator are illustrated concerning the Shehu transformation to demonstrate their utility. Additionally, a general technique for Atangana-Baleanu fuzzy fractional derivatives is proposed in the sense of Caputo. It is important to note that the purpose of the suggested fuzziness technique is to establish the efficiency and accuracy of analytical solution to nonlinear fuzzy fractional partial differential equations that emerge in complex and physical structures.

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Ali, Gauhar, Ghazala Nazir, Kamal Shah et Yongjin Li. « Existence Theory and Novel Iterative Method for Dynamical System of Infectious Diseases ». Discrete Dynamics in Nature and Society 2020 (1 juin 2020) : 1–11. http://dx.doi.org/10.1155/2020/8709393.

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This manuscript is devoted to investigate qualitative theory of existence and uniqueness of the solution to a dynamical system of an infectious disease known as measles. For the respective theory, we utilize fixed point theory to construct sufficient conditions for existence and uniqueness of the solution. Some results corresponding to Hyers–Ulam stability are also investigated. Furthermore, some semianalytical results are computed for the considered system by using integral transform due to the Laplace and decomposition technique of Adomian. The obtained results are presented by graphs also.

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Song, Lina. « A Semianalytical Solution of the Fractional Derivative Model and Its Application in Financial Market ». Complexity 2018 (2018) : 1–10. http://dx.doi.org/10.1155/2018/1872409.

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Fractional differential equation has been introduced to the financial theory, which presents new ideas and tools for the theoretical researches and the practical applications. In the work, an approximate semianalytical solution of the time-fractional European option pricing model is derived using the method of combining the enhanced technique of Adomian decomposition method with the finite difference method. And then the result is introduced in China’s financial market. The work makes every effort to test the feasibility of the fractional derivative model in the actual financial market.

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Dai, Zhijiang, Songbai He, Jun Peng, Chaoyi Huang, Weimin Shi et Jingzhou Pang. « A Semianalytical Matching Approach for Power Amplifier With Extended Chebyshev Function and Real Frequency Technique ». IEEE Transactions on Microwave Theory and Techniques 65, n^o 10 (octobre 2017) : 3892–902. http://dx.doi.org/10.1109/tmtt.2017.2687899.

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Nélias, Daniel, Eduard Antaluca, Vincent Boucly et Spiridon Cretu. « A Three-Dimensional Semianalytical Model for Elastic-Plastic Sliding Contacts ». Journal of Tribology 129, n^o 4 (24 mai 2007) : 761–71. http://dx.doi.org/10.1115/1.2768076.

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A three-dimensional numerical model based on a semianalytical method in the framework of small strains and small displacements is presented for solving an elastic-plastic contact with surface traction. A Coulomb’s law is assumed for the friction, as commonly used for sliding contacts. The effects of the contact pressure distribution and residual strain on the geometry of the contacting surfaces are derived from Betti’s reciprocal theorem with initial strain. The main advantage of this approach over the classical finite element method (FEM) is the computing time, which is reduced by several orders of magnitude. The contact problem, which is one of the most time-consuming procedures in the elastic-plastic algorithm, is obtained using a method based on the variational principle and accelerated by means of the discrete convolution fast Fourier transform (FFT) and conjugate gradient methods. The FFT technique is also involved in the calculation of internal strains and stresses. A return-mapping algorithm with an elastic predictor∕plastic corrector scheme and a von Mises criterion is used in the plasticity loop. The model is first validated by comparison with results obtained by the FEM. The effect of the friction coefficient on the contact pressure distribution, subsurface stress field, and residual strains is also presented and discussed.

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Labaki, Josue, Edivaldo Romanini et Euclides Mesquita. « Stationary Dynamic Displacement Solutions for a Rectangular Load Applied within a 3D Viscoelastic Isotropic Full Space—Part II : Implementation, Validation, and Numerical Results ». Mathematical Problems in Engineering 2012 (2012) : 1–16. http://dx.doi.org/10.1155/2012/515367.

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In part I of the present article the formulation for a dynamic stationary semianalytical solution for a spatially constant load applied over a rectangular surface within a viscoelastic isotropic full-space has been presented. The solution is obtained within the frame of a double Fourier integral transform. These inverse integral transforms must be evaluated numerically. In the present paper, the technique to evaluate numerically the inverse double Fourier integrals is described. The procedure is validated, and a number of original displacement results for the stationary loading case are reported.

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Aksenov, Sergey A., Ivan Y. Zakhariev, Aleksey V. Kolesnikov et Sergey A. Osipov. « Characterization of Superplastic Materials by Results of Free Bulging Tests ». Materials Science Forum 838-839 (janvier 2016) : 552–56. http://dx.doi.org/10.4028/www.scientific.net/msf.838-839.552.

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Determination of material constants describing its behavior during superplastic gas forming is the main subject of this study. The main feature of free bulging tests is the stress-strain conditions which are very similar to ones occurring in the most of gas forming processes. On the other hand, the interpretation of the results of such tests is a complicated procedure. The paper presents a simple technique for the characterization of materials superplasticity by free bulging tests, which is based on inverse analysis. The main idea of this technique is a semianalytical solution of the direct problem instead of finite element simulation which allows one to reduce the calculation time significantly. At the same time the results this simplified solution are accurate enough to obtain realistic material constants.

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Heidari, M., S. H. Hejazi et S. M. Farouq Ali. « Steam-Assisted Gravity-Drainage Performance With Temperature-Dependent Properties—A Semianalytical Approach ». SPE Journal 22, n^o 03 (20 octobre 2016) : 902–11. http://dx.doi.org/10.2118/175036-pa.

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Summary Steam-assisted gravity drainage (SAGD) is one of the successful in-situ thermal-recovery methods for oil-sands production. In this paper, we provide a simple semianalytical model that can accurately analyze an SAGD project with variable properties. In particular, we investigate the effect of temperature-dependent properties such as thermal conductivity, heat capacity, and rock density on SAGD performance. The proposed model sequentially solves the transient nonlinear heat-transfer equation coupled with the continuity equation with Kirchhoff's transformation and the heat integral method (HIM). A criterion for timestep selection is defined on the basis of the Courant and Péclet numbers to guarantee the stability of the sequential technique. The results illustrate that the temperature-dependent physical properties affect temperature distributions ahead of steam chamber which consequently have a significant impact on the cumulative oil production and oil-production rate. Moreover, the results show that the temperature profile ahead of the steam chamber changes with time and space, and a 2D transient assumption for SAGD modeling is necessary. The semianalytical model runs in a small fraction of numerical-simulator runtime, yet it provides reasonable results. Thus, it has the potential to be used as a tool for quick SAGD evaluations.

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Chen, Zhiming, Xinwei Liao, Kamy Sepehrnoori et Wei Yu. « A Semianalytical Model for Pressure-Transient Analysis of Fractured Wells in Unconventional Plays With Arbitrarily Distributed Discrete Fractures ». SPE Journal 23, n^o 06 (7 septembre 2018) : 2041–59. http://dx.doi.org/10.2118/187290-pa.

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Summary In this paper, we present an efficient semianalytical model for pressure-transient analysis in fractured wells by considering arbitrarily distributed fracture networks. The semianalytical model included three domains: matrix, hydraulic-fracture networks, and discrete natural fractures. Using the line-source function, we developed the diffusivity equation for fluid flow in matrix. By applying the vertex-analysis technique, we eliminated the flow interplay at fracture intersections and established the diffusivity equations for fluid flow in hydraulic-fracture networks and isolated natural fractures. The pressure-transient solution of these diffusivity equations was obtained using Laplace transforms and the Stehfest numerical inversion. Results showed that with the discrete natural fractures, a “V-shaped” pressure derivative (the classical dual-porosity feature of naturally fractured reservoirs) emerged. With the hydraulic-fracture networks, the reservoir system would exhibit pressure behaviors such as “pseudoboundary-dominated flow,” “fracture-interference flow,” and “fluid-feed flow.” All these pressure characteristics were dependent on the properties and geometries of natural/hydraulic fractures. In addition, through synthetic field application, we found that different (natural/hydraulic) fracture distributions and geometries had distinct behaviors of pressure derivatives, which may provide an effective tool to identify the properties of randomly distributed natural fractures as well as complex hydraulic fractures in unconventional plays.

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Isaac, George, et Diaa Khalil. « A Semianalytical Technique for Leaky-Mode Loss Calculation in Hollow Dielectric Waveguides With Arbitrary Cross Sections ». Journal of Lightwave Technology 25, n^o 9 (septembre 2007) : 2337–44. http://dx.doi.org/10.1109/jlt.2007.901452.

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Lara, Martin, Juan F. San-Juan et Luis M. López-Ochoa. « Averaging Tesseral Effects : Closed Form Relegation versus Expansions of Elliptic Motion ». Mathematical Problems in Engineering 2013 (2013) : 1–11. http://dx.doi.org/10.1155/2013/570127.

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Longitude-dependent terms of the geopotential cause nonnegligible short-period effects in orbit propagation of artificial satellites. Hence, accurate analytical and semianalytical theories must cope with tesseral harmonics. Modern algorithms for dealing analytically with them allow for closed formrelegation. Nevertheless, current procedures for the relegation of tesseral effects from subsynchronous orbits are unavoidably related to orbit eccentricity, a key fact that is not enough emphasized and constrains application of this technique to small and moderate eccentricities. Comparisons with averaging procedures based on classical expansions of elliptic motion are carried out, and the pros and cons of each approach are discussed.

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Li, Junpu, Wen Chen et Zhuojia Fu. « Numerical Investigation on Convergence Rate of Singular Boundary Method ». Mathematical Problems in Engineering 2016 (2016) : 1–13. http://dx.doi.org/10.1155/2016/3564632.

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The singular boundary method (SBM) is a recent boundary-type collocation scheme with the merits of being free of mesh and integration, mathematically simple, and easy-to-program. Its essential technique is to introduce the concept of the source intensity factors to eliminate the singularities of fundamental solutions upon the coincidence of source and collocation points in a strong-form formulation. In recent years, several numerical and semianalytical techniques have been proposed to determine source intensity factors. With the help of these latest techniques, this short communication makes an extensive investigation on numerical efficiency and convergence rates of the SBM to an extensive variety of benchmark problems in comparison with the BEM. We find that in most cases the SBM and BEM have similar convergence rates, while the SBM has slightly better accuracy than the direct BEM. And the condition number of SBM is lower than BEM. Without mesh and numerical integration, the SBM is computationally more efficient than the BEM.

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Kundu, B. « Performance and Optimization of Flat Plate Fins of Different Geometry on a Round Tube : A Comparative Investigation ». Journal of Heat Transfer 129, n^o 7 (13 janvier 2007) : 917–26. http://dx.doi.org/10.1115/1.2717255.

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Owing to a uniform thickness, the fin material of a flat plate fin near to the tip does not participate optimally in transferring heat. On account of this, two new fin geometries of flat plate fins are proposed for improving the heat transfer rate per unit volume. These projected fin geometries, namely flat plate fin circumscribing a circular tube by providing quarter circular cut at the corners of the tip (FQCT) and flat plate fin circumscribing a circular tube having circular arc to cut at the tip (FCAT) are suggested. The thermal performance of the said geometric fins has been determined by a semianalytical method. By using a rigorous semianalytical technique, optimization have been demonstrated in a generalized scheme either by maximizing the rate of heat duty for a given fin volume or by minimizing the fin volume for a given heat transfer duty. The optimization study has also been made with the additional length constraints imposed on one or both sides of the fluid carrying tube. Finally, it can be demonstrated from the optimization study that two proposed fins, namely FQCT and FCAT, can dissipate more rate of heat than the FCT with an identical fin volume and thermophysical parameters. It can also be highlighted that the optimum FQCT and FCAT can transfer heat at a higher rate in comparison with the annular disk fin when a space constraint exists.

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Chen, Jie, Hai Wang et Jie Wang. « Buckling and vibration analyses of composite laminates with weak interfaces by a coupled meshfree and finite element method ». Science and Engineering of Composite Materials 23, n^o 1 (1 janvier 2016) : 93–105. http://dx.doi.org/10.1515/secm-2014-0102.

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AbstractBuckling and free vibration analyses for composite laminates with weak interfaces were performed based on a three-dimensional hybrid semianalytical model. The model was established by coupling the radial point interpolation method and finite element method (FEM) in a Hamilton system. A direct coupling approach was developed based on the FEM background cell algorithm, and a modified Hamiltonian function for buckling analysis of rectangular laminated plates was given. The governing equations were deduced with the transfer matrix technique and a general linear spring layer model based on the modified Hellinger-Reissner variational principle. Several numerical examples are also presented to validate the efficiency and accuracy of the present method.

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Yen, David Wei, et Paul K. Wright. « A Remote Temperature Sensing Technique for Estimating the Cutting Interface Temperature Distribution ». Journal of Engineering for Industry 108, n^o 4 (1 novembre 1986) : 252–63. http://dx.doi.org/10.1115/1.3187075.

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Cutting temperature is a major factor in controlling tool wear rate. Thus, sensing and control of cutting temperature is important in achieving a desired tool performance. This paper is concerned with estimating the cutting interface temperature distribution based on remote temperature measurements. This class of problems of estimating unknown boundary conditions from known interior quantities is called the inverse problem. The inverse problem of a square insert under steady state conditions is considered in this paper. The temperature distribution in a square insert is best described in Ellipsoidal Coordinates. The mapping functional in the one-dimensional case is solved analytically. The mapping functionals in general three-dimensional cases are solved numerically using the semianalytical finite element method. The mapping functional in a three-dimensional case is represented by a transformation matrix which maps one vector representing the cutting interface temperature distribution to another vector representing the remote temperatures. The transformation matrix is then used to solve the inverse problem of estimating the interface temperature distribution with redundant remote measurements. Measurement errors and transformation matrix errors are imposed in simulation studies. The sensitivity of inverse solutions to these errors is discussed.

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Hamdi, Hamidreza, Hamid Behmanesh et Christopher R. Clarkson. « A Semianalytical Approach for Analysis of Wells Exhibiting Multiphase Transient Linear Flow : Application to Field Data ». SPE Journal 25, n^o 06 (21 août 2020) : 3265–79. http://dx.doi.org/10.2118/196164-pa.

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Summary Rate-transient analysis (RTA) is a useful reservoir/hydraulic fracture characterization method that can be applied to multifractured horizontal wells (MFHWs) producing from low-permeability (tight) and shale reservoirs. In this paper, we applied a recently developed three-phase RTA technique to the analysis of production data from an MFHW completed in a low-permeability volatile oil reservoir in the Western Canadian Sedimentary Basin. This RTA technique is used to analyze the transient linear flow regime for wells operated under constant flowing bottomhole pressure (BHP) conditions. With this method, the slope of the square-root-of-time plot applied to any of the producing phases can be used to directly calculate the linear flow parameter xfk without defining pseudovariables. The method requires a set of input pressure/volume/temperature (PVT) data and an estimate of two-phase relative permeability curves. For the field case studied herein, the PVT model is constructed by tuning an equation of state (EOS) from a set of PVT experiments, while the relative permeability curves are estimated from numerical model history-matchingresults. The subject well, an MFHW completed in 15 stages, produces oil, water, and gas at a nearly constant (measured downhole) flowing BHP. This well is completed in a low-permeability,near-critical volatile oil system. For this field case, application of the recently proposed RTA method leads to an estimate of xfk that is in close agreement (within 7%) with the results of a numerical model history match performed in parallel. The RTA method also provides pressure–saturation (P–S) relationships for all three phases that are within 2% of those derived from the numerical model. The derived P–S relationships are central to the use of other RTA methods that require calculation of multiphase pseudovariables. The three-phase RTA technique developed herein is a simple-yet-rigorous and accurate alternative to numerical model history matching for estimating xfk when fluid properties and relative permeability data are available.

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Eldabe, N. T., G. M. Moatimid, M. Y. Abouzeid, A. A. ElShekhipy et Naglaa F. Abdallah. « A semianalytical technique for MHD peristalsis of pseudoplastic nanofluid with temperature-dependent viscosity : Application in drug delivery system ». Heat Transfer-Asian Research 49, n^o 1 (5 novembre 2019) : 424–40. http://dx.doi.org/10.1002/htj.21619.

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Abouelmagd, Elbaz I., Daniele Mortari et Hadia H. Selim. « Analytical Study of Periodic Solutions on Perturbed Equatorial Two-Body Problem ». International Journal of Bifurcation and Chaos 25, n^o 14 (30 décembre 2015) : 1540040. http://dx.doi.org/10.1142/s0218127415400404.

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This paper presents analytical derivations to study periodic solutions for the two-body problem perturbed by the first zonal harmonic parameter. In particular, three different semianalytical approaches to solve this problem have been studied: (1) the classic perturbation theory, (2) the Lindstedt–Poincaré technique, and (3) the Krylov–Bogoliubov–Mitropolsky method. In addition, the numerical integration by Runge–Kutta algorithm is established. However, the numerical comparison tests show that by increasing the value of angular momentum the solutions provided by Lindstedt–Poincaré and Krylov–Bogoliubov–Mitropolsky methods become similar, and they provide almost identical results using a smaller value for the perturbed parameter which quantify the dynamical flattening of the main body, the Krylov–Bogoliubov–Mitropolsky provides more accurate results to design elliptical periodic solutions than Lindstedt–Poincaré technique when the perturbed parameter has a relatively large value, regardless of the value of angular momentum. This study can be applied to equatorial orbits to obtain closed-form analytical solutions.

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Hazlett, Randy Doyle, D. Krishna Babu et Larry Wayne Lake. « Semianalytical Stream-Function Solutions on Unstructured Grids for Flow in Heterogeneous Media ». SPE Journal 12, n^o 02 (1 juin 2007) : 179–87. http://dx.doi.org/10.2118/95913-pa.

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Summary This paper outlines a Boundary Element Method (BEM) for a piece-wise analytic solution of the Laplace (Poisson) equation for pseudosteady-state, single-phase flow on unstructured, rectangular grids. The method models flow through a reservoir that has been segmented into interacting homogeneous rectangular regions; no further discretization of the solution space analogous to grid refinement in numerical schemes is required for improved accuracy. Rather, boundary discretization allows for continuation of pressure and flux. Previous work on pressure distribution modeling is extended to analytically capture the stream function. Stream-function solutions can then form the basis for other performance measures, such as improved oil recovery efficiency estimation or tracer flow analysis. Moving beyond structured grids into unstructured grid geometry allows for advanced flexibility in problem development and improved efficiency in solution construction. The analytic approach avoids the need for numerical differentiation of the pressure field and particle tracking methods to recover streamlines. Capturing flow in highly heterogeneous media, without local grid refinement, is demonstrated to showcase the robustness of the technique in handling complex reservoir architecture, of particular interest in optimal well positioning and optimal well-pattern development. Introduction The solution to fluid flow problems is typically a map of the driving force (i.e., potential or pressure). A more intuitive result is a map that shows actual trajectories of fluid elements, the stream function (Muskat 1937). Potential, F, and stream-function, ?, are related in 2D by their spatial gradients. (Eq. 1) Curves of constant stream-function value are the so-called streamlines. Stream-function indexing is associated with integration, as the difference in stream-function indices represents the amount of fluid flowing between streamlines of those fixed values. By definition, no fluid convection occurs across a streamline. Unfortunately, the concept of stream function is restricted to two dimensions. While an orthogonal mesh to the pressure field can certainly be constructed in 3D, an equivalent of stream function is found in three dimensions only for flows exhibiting symmetry properties that effectively reduce the dimensionality of the flow problem.

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Fokker, Peter A., Francesca Verga et Paul Egberts. « New Semi-Analytic Technique to Determine Horizontal Well PI in Fractured Reservoirs ». SPE Reservoir Evaluation & ; Engineering 8, n^o 02 (1 avril 2005) : 123–31. http://dx.doi.org/10.2118/84597-pa.

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Summary Simplified analytical relations derived for homogeneous formations are usually applied to the determination of the productivity of horizontal wells, regardless of the presence of heterogeneities in the reservoir. Furthermore, complex well architectures and the wealth of completion options currently available cannot be taken into account properly because the well trajectory can only be schematized as a single horizontal wellbore. However, the use of numerical reservoir simulators to reliably forecast the productivity of horizontal wells draining heterogeneous reservoirs may be time-prohibitive or not feasible because of a lack of sufficiently detailed information, especially during the appraisal phase or the early stages of production. A new semianalytic technique is proposed in this paper to solve the inflow equations in an approximate yet reliable manner. A solution to 3D problems of single-phase flow into a horizontal well, taking into account friction in the wellbore, is provided for both single-layer reservoirs and reservoirs comprising two interfering layers. The method also has been extended to describe the fluid flow when the well intercepts one or more fractures. The presented technique allows very fast calculation of the well productivity in oil and gas reservoirs, offering great flexibility in the placement and architecture of the wells. The method has been applied to two field cases for which the well productivity under pseudosteady-state conditions was measured. One of these is a 200-m-long horizontal well draining an isotropic carbonatic reservoir and intersected by a natural low-conductivity fracture. The other is a similar well, intercepting a natural high-conductivity fault, but the oil-bearing formation is anisotropic. Good correspondence was found between the actual productivity and the predictions obtained by application of the proposed semianalytic technique. Introduction Horizontal wells are common practice in the present hydrocarbon industry, and smart wells (including multilateral completions and wells with selective access of different zones) are becoming increasingly commonplace. The modeling of such wells is, in many cases, not ideal. Areas in which improvements are welcome are well testing, well models in reservoir simulators, and fast models for quick assessment of many field-development options. Further, the handling of natural or hydraulic fractures is often suboptimal. In reservoir simulation, fine grids need to be selected to properly capture the flow behavior close to the well. Moreover, most reservoir simulators are not equipped with extensive well models, which are required when friction in the well becomes important or when two-phase flow develops in the well. This situation has prompted the development of a number of analytical and semianalytical tools, some of which are intended for implementation in a reservoir simulator. Most of the first models, as well as many of the more recent models, assume either constant influx density along the well or infinite well conductivity in a single homogeneous layer. Dikken introduced the effect of well conductivity for a single horizontal well in a homogeneous formation. He started with the assumption that the flow is mainly perpendicular to the wellbore, which allowed him to reduce the reservoir to a 2D flow domain, coupled to a friction model in the well. Others followed this approach, but 3Dmodels were developed as well. A second kind of extension are the multilayer models. Lee and Milliken and Kuchuk and Habashy used a method of reflection and transmission, while Basquet et al. used a "quadrupole" method relating the pressures between the various layers. The multilayer models are also, however, still limited to constant-influx or infinite-conductivity wells.

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Glushkov, E. V., N. V. Glushkova et C. S. Chen. « SemiAnalytical Solution to Heat Transfer Problems Using Fourier Transform Technique, Radial Basis Functions, and the Method of Fundamental Solutions ». Numerical Heat Transfer, Part B : Fundamentals 52, n^o 5 (29 août 2007) : 409–27. http://dx.doi.org/10.1080/10407790701443859.

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Guo, Qiwei, Hanlun Lei et Bo Xu. « Semianalytical Solutions of Relative Motions with Applications to Periodic Orbits about a Nominal Circular Orbit ». Mathematical Problems in Engineering 2018 (9 juillet 2018) : 1–14. http://dx.doi.org/10.1155/2018/4183941.

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In the dynamical model of relative motion with circular reference orbit, the equilibrium points are distributed on the circle where the leader spacecraft is located. In this work, analytical solutions of periodic configurations around an arbitrary equilibrium point are constructed by taking Lindstedt-Poincaré (L-P) and polynomial expansion methods. Based on L-P approach, periodic motions are expanded as formal series of in-plane and out-of-plane amplitudes. According to the method of polynomial expansions, a pair of modal coordinates is chosen, and the remaining state variables are expressed as polynomial series about the modal coordinates. In order to check the validity of series solutions constructed, the practical convergence is evaluated. Considering the fact that relative motion model is a special case of restricted three-body problem, the periodic configurations constructed in the model of relative motion are taken as starting solutions to numerically identify the periodic orbits in restricted three-body problem by means of continuation technique with the mass of system as continuation parameter.

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Deng, Guodong, Jiasheng Zhang, Wenbing Wu, Xiong Shi et Fei Meng. « Soil-Pile Interaction in the Pile Vertical Vibration Based on Fictitious Soil-Pile Model ». Journal of Applied Mathematics 2014 (2014) : 1–11. http://dx.doi.org/10.1155/2014/905194.

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By introducing the fictitious soil-pile model, the soil-pile interaction in the pile vertical vibration is investigated. Firstly, assuming the surrounding soil of pile to be viscoelastic material and considering its vertical wave effect, the governing equations of soil-pile system subjected to arbitrary harmonic dynamic force are founded based on the Euler-Bernoulli rod theory. Secondly, the analytical solution of velocity response in frequency domain and its corresponding semianalytical solution of velocity response in time domain are derived by means of Laplace transform technique and separation of variables technique. Based on the obtained solutions, the influence of parameters of pile end soil on the dynamic response is studied in detail for different designing parameters of pile. Lastly, the fictitious soil-pile model and other pile end soil supporting models are compared. It is shown that the dynamic response obtained by the fictitious soil-pile model is among the dynamic responses obtained by other existing models if there are appropriate material parameters and thickness of pile end soil for the fictitious soil-pile model.

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Shah, Nehad Ali, A. Al-Zubaidi et S. Saleem. « Study of Magnetohydrodynamic Pulsatile Blood Flow through an Inclined Porous Cylindrical Tube with Generalized Time-Nonlocal Shear Stress ». Advances in Mathematical Physics 2021 (17 mai 2021) : 1–11. http://dx.doi.org/10.1155/2021/5546701.

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The effects of pulsatile pressure gradient in the presence of a transverse magnetic field on unsteady blood flow through an inclined tapered cylindrical tube of porous medium are discussed in this article. The fractional calculus technique is used to provide a mathematical model of blood flow with fractional derivatives. The solution of the governing equations is found using integral transformations (Laplace and finite Hankel transforms). For the semianalytical solution, the inverse Laplace transform is found by means of Stehfest’s and Tzou’s algorithms. The numerical calculations were performed by using Mathcad software. The flow is significantly affected by Hartmann number, inclination angle, fractional parameter, permeability parameter, and pulsatile pressure gradient frequency, according to the findings. It is deduced that there exists a significant difference in the velocity of the flow at higher time when the magnitude of Reynolds number is small and large.

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Shah, Nehad Ali, Essam R. El-Zahar, Ali Akgül, Adnan Khan et Jeevan Kafle. « Analysis of Fractional-Order Regularized Long-Wave Models via a Novel Transform ». Journal of Function Spaces 2022 (6 juin 2022) : 1–16. http://dx.doi.org/10.1155/2022/2754507.

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A new integral transform method for regularized long-wave (RLW) models having fractional-order is presented in this study. Although analytical approaches are challenging to apply to such models, semianalytical or numerical techniques have received much attention in the literature. We propose a new technique combining integral transformation, the Elzaki transform (ET), and apply it to regularized long-wave equations in this study. The RLW equations describe ion-acoustic waves in plasma and shallow water waves in seas. The results obtained are extremely important and necessary for describing various physical phenomena. This work considers an up-to-date approach and fractional operators in this context to obtain satisfactory approximate solutions to the proposed problems. We first define the Elzaki transforms of the Caputo fractional derivative (CFD) and Atangana-Baleanu fractional derivative (ABFD) and implement them for solving RLW equations. We can readily obtain numerical results that provide us with improved approximations after only a few iterations. The derived solutions were found to be in close contact with the exact solutions. Furthermore, the suggested procedure has attained the best level of accuracy. In fact, when compared to other analytical techniques for solving nonlinear fractional partial differential equations, the present method might be considered one of the finest.

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Kahrobaei, S., M. Mansoori Habibabadi, G. J. Joosten, P. M. Van den Hof et J. D. Jansen. « Identifiability of Location and Magnitude of Flow Barriers in Slightly Compressible Flow ». SPE Journal 21, n^o 03 (15 juin 2016) : 0899–908. http://dx.doi.org/10.2118/173235-pa.

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Summary Classic identifiability analysis of flow barriers in incompressible single-phase flow reveals that it is not possible to identify the location and permeability of low-permeability barriers from production data (wellbore pressures and rates), and that only averaged reservoir properties in between wells can be identified. We extend the classic analysis by including compressibility effects. We use two approaches: a twin experiment with synthetic production data for use with a time-domain parameter-estimation technique, and a transfer-function formalism in the form of bilaterally coupled four-ports allowing for an analysis in the frequency domain. We investigate the identifiability, from noisy production data, of the location and the magnitude of a low-permeability barrier to slightly compressible flow in a 1D configuration. We use an unregularized adjoint-based optimization scheme for the numerical time-domain estimation, by use of various levels of sensor noise, and confirm the results by use of the semianalytical transfer-function approach. Both the numerical and semianalytical results show that it is possible to identify the location and the magnitude of the permeability in the barrier from noise-free data. By introducing increasingly higher noise levels, the identifiability gradually deteriorates, but the location of the barrier remains identifiable for much-higher noise levels than the permeability. The shape of the objective-function surface, in normalized variables, indeed indicates a much-higher sensitivity of the well data to the location of the barrier than to its magnitude. These theoretical results appear to support the empirical finding that unregularized gradient-based history matching in large reservoir models, which is well-known to be a severely ill-posed problem, occasionally leads to useful results in the form of model-parameter updates with unrealistic magnitudes but indicating the correct location of model deficiencies.

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