Articles de revues : « Parameter-free technique »

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Hanuman, Sai A., Vinaya A. Babu, A. Govardhan et S. C. Satapathy. « Data Clustering using almost parameter free Differential Evolution technique ». International Journal of Computer Applications 8, n^o 13 (10 octobre 2010) : 1–7. http://dx.doi.org/10.5120/1310-1811.

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Geem, Zong Woo. « Economic Dispatch Using Parameter-Setting-Free Harmony Search ». Journal of Applied Mathematics 2013 (2013) : 1–5. http://dx.doi.org/10.1155/2013/427936.

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Economic dispatch is one of the popular energy system optimization problems. Recently, it has been solved by various phenomenon-mimicking metaheuristic algorithms such as genetic algorithm, tabu search, evolutionary programming, particle swarm optimization, harmony search, honey bee mating optimization, and firefly algorithm. However, those phenomenon-mimicking problems require a tedious and troublesome process of algorithm parameter value setting. Without a proper parameter setting, good results cannot be guaranteed. Thus, this study adopts a newly developed parameter-setting-free technique combined with the harmony search algorithm and applies it to the economic dispatch problem for the first time, obtaining good results. Hopefully more researchers in energy system fields will adopt this user-friendly technique in their own problems in the future.

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Bar-Meir, Genick. « Analysis of Mass Transfer Process in the Pore Free Technique ». Journal of Engineering Materials and Technology 117, n^o 2 (1 avril 1995) : 215–19. http://dx.doi.org/10.1115/1.2804532.

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Air entrainment is one of the most significant problems in pressure die casting. A possible solution is to use the Pore Free technique. In this technique an oxygen is introduced into the die to react with the liquid metal. The vacuum created by the reaction reduces the porosity. The life span of the mold is augmented by the reduction of the pressure during the process. In some cases the Pore Free technique yields acceptable results, i.e., low porosity, while in other cases the results are not satisfactory. These differing results can be explained by an analysis of the mechanisms involved. A simple model is proposed based on conservation laws that describes the relationship between mass transfer mechanisms and pressure deviation. The model indicates that there is a critical dimensionless parameter above which the pressure is decreased and below which the pressure is increased. In the first case, when the parameter exceeds the critical value, the technique is useful. In the second case, when the parameter is less than the critical value, introducing oxygen does not greatly reduce the porosity. The analysis demonstrates that the Pore Free and vacuum venting techniques account for two different extremes. The first case is when the flow is orderly throughout the chamber in which vacuum venting can produce acceptable results. The second case is when the flow is turbulent and the Pore Free technique is the better choice.

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Guchhait, Shyamal, et Biswanath Banerjee. « Constitutive error based parameter estimation technique for plate structures using free vibration signatures ». Journal of Sound and Vibration 419 (avril 2018) : 302–17. http://dx.doi.org/10.1016/j.jsv.2018.01.020.

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Pinit, Pichet, Tobita Susumu et Eisaku Umezaki. « Determination of Principal-Stress Directions by Three-Step Color Phase Shifting Technique ». Key Engineering Materials 321-323 (octobre 2006) : 1284–87. http://dx.doi.org/10.4028/www.scientific.net/kem.321-323.1284.

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A three-step phase shifting approach for automatic determination of the isoclinic parameter in photoelasticity is presented. Unreliable isoclinic values affected by the isochromatic parameter are solved using the white light. The method uses three fringe images digitally captured by a digital camera for three different configurations of the dark-field plane polariscope. For a circular disk under compression, results show the method permits the isoclinic parameter in the range -π/2 to π/2 with almost free of the isochromatic parameter and comparable with theory.

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Wu, Qing, et Li Xing Yuan. « A Smooth Clustering Algorithm Based on Parameter Free Filled Function ». Advanced Materials Research 143-144 (octobre 2010) : 389–93. http://dx.doi.org/10.4028/www.scientific.net/amr.143-144.389.

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In this paper, we propose an algorithm to find centers of clusters based on adjustable entropy technique. A completely differentiable non-convex optimization model for the clustering center problem is constructed. A parameter free filled function method is adopted to search for a global optimal solution of the optimization model. The proposed algorithm can avoid the numerical overflow phenomenon. Numerical results illustrate that the proposed algorithm can effectively hunt centers of clusters and especially improve the accuracy of the clustering even with a relatively small entropy factor.

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Hendry, Martin A., et Stéphane Rauzy. « A Robust Technique for Estimating Cosmological Parameters ». Symposium - International Astronomical Union 201 (2005) : 467–68. http://dx.doi.org/10.1017/s0074180900216707.

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We present a new ROBUST technique for extracting information from galaxy surveys which allows determination of cosmological parameters free of almost any model assumptions concerning the galaxy luminosity function and spatial clustering. We illustrate ROBUST by estimating H0 and the linear bias parameter, β, from recent redshift-distance data.

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Ma, Zheng-Dong, Noboru Kikuchi, Hsien-Chie Cheng et Ichiro Hagiwara. « Topological Optimization Technique for Free Vibration Problems ». Journal of Applied Mechanics 62, n^o 1 (1 mars 1995) : 200–207. http://dx.doi.org/10.1115/1.2895903.

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A topological optimization technique using the conception of OMD (Optimal Material Distribution) is presented for free vibration problems of a structure. A new objective function corresponding to multieigenvalue optimization is suggested for improving the solution of the eigenvalue optimization problem. An improved optimization algorithm is then applied to solve these problems, which is derived by the authors using a new convex generalized-linearization approach via a shift parameter which corresponds to the Lagrange multiplier and the use of the dual method. Finally, three example applications are given to substantiate the feasibility of the approaches presented in this paper.

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Mannarelli, Massimo. « The improved Ginzburg-Landau technique ». EPJ Web of Conferences 192 (2018) : 00021. http://dx.doi.org/10.1051/epjconf/201819200021.

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We discuss an innovative method for the description of inhomogeneous phases designed to improve the standard Ginzburg-Landau expansion. The method is characterized by two key ingredients. The first one is a moving average of the order parameter designed to account for the long-wavelength modulations of the condensate. The second one is a sum of the high frequency modes, to improve the description of the phase transition to the restored phase. The method is applied to compare the free energies of 1D and 2D inhomogeneous structures arising in the chirally symmetric broken phase.

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Baciu, Andrei, et Corneliu Lazar. « Iterative Feedback Tuning of Model-Free Intelligent PID Controllers ». Actuators 12, n^o 2 (28 janvier 2023) : 56. http://dx.doi.org/10.3390/act12020056.

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In the last decades, model-free control (MFC) has become an alternative for complex processes whose models are not available or are difficult to obtain. Among the model-free control techniques, intelligent PID (iPID) algorithms, which are based on the ultralocal model parameterized with the constant α and including a classical PID, are used in many applications. This paper presents a new method for tuning iPID controllers based on the iterative feedback tuning (IFT) technique. This model-free tuning technique iteratively optimizes the parameters of a fixed structure controller using data coming from the closed-loop system operation. First, the discrete transfer functions of the iPID are deduced, considering the first and second order derivatives of the output variable from the ultralocal model. Using the discrete transfer functions, the iPID controllers become the fixed structure type, and the IFT parameter tuning method can be applied. Thus, in addition to the classical gains of the PID algorithm, the value of the parameter α is also obtained, which is usually determined by trial-and-error. The performances of the IFT-tuned iPID controllers were experimentally tested and validated in real-time using Quanser AERO 2 laboratory equipment with a one degree of freedom (1-DOF) configuration.

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Khan, Ilyas, Tarek Nabil Ahmed Abdelhameed et L. C. C. Dennis. « Heat Transfer in Eccentric-Concentric Rotation of a Disk and Fluid at Infinity ». Journal of Computational and Theoretical Nanoscience 13, n^o 10 (1 octobre 2016) : 6482–87. http://dx.doi.org/10.1166/jctn.2016.5590.

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Heat transfer due to free convection flow in eccentric-concentric rotation of a disk and fluid at infinity is studied in this work Exact solutions for velocity and temperature are obtained by using the Laplace transform technique. The performed calculations disclose that the free convection parameter, Prandtl number, radiation parameter, and dimensionless time have strong influence on fluid velocity and temperature. The graphs are presented for such influence and examined carefully.

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Kumar, Mahesh. « Study of differential transform technique for transient hydromagnetic Jeffrey fluid flow from a stretching sheet ». Nonlinear Engineering 9, n^o 1 (7 février 2020) : 145–55. http://dx.doi.org/10.1515/nleng-2020-0004.

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AbstractThis article investigates the time-dependent MHD heat transfer flow of Jeffrey fluid from a stretching sheet, the topic significance to non-Newtonian viscoelastic material processing. Using similarity transformations, the governing coupled non-linear PDE’s are remodel into ODE’s with suitable free stream and wall boundary conditions. The developed non-dimensional non-linear problem is revealed to be analysed by several key thermosphysical and rheological parameters, namely, Jeffrey fluid parameter (λ), Deborah number (β), Prandtl number (Pr), buoyancy parameter (ξ), magnetic parameter (M) and unsteadiness parameter (A). The semi-exact differential transform technique is applied to elucidate the coupled nonlinear governing equation of non-Newtonian Jeffrey fluid problem. Also, the solution is validated with numerical results attained via the MATLAB bvp4c function. Excellent accurateness is attained through the DTM approach. Further validation with available consequences from the existing literature is incorporated. The results indicate that fluid velocity and temperature are boosted with increasing Deborah number and stretching parameter however it shows a decreasing trend with Jeffrey fluid parameter and convection parameter. It also shows when augmenting the magnetic parameter which reduces the flow and increases the thickness of the boundary layer.

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Filaretov, Vladimir, Konstantin Gorshkov et Sergey Kurganov. « A Cancellation-Free Symbolic Sensitivity Technique Based on Network Determinant Expansion ». Advances in Electrical Engineering 2015 (18 janvier 2015) : 1–13. http://dx.doi.org/10.1155/2015/328517.

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The generalization of Bode’s sensitivity analysis technique for all types of the transfer functions and circuit elements is presented in the paper. The proposed formulae for first- and second-order symbolic sensitivity calculation provide the compact size of obtained expression and have the advantages of cancellation-free sum-of-product terms and matrix-free computation. This is achieved by means of the concept of high order summative cofactors and the generalized parameter extraction method. The proposed technique is implemented in symbolic circuit analysis program Cirsym. Illustrative example on symbolic sensitivity circuit analysis and comparison of the presented technique with the transimpedance method and the method based on the modified Coates flow-graph are given.

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Low, Kenny W. Q., Chun Hean Lee, Antonio J. Gil, Jibran Haider et Javier Bonet. « A parameter-free total Lagrangian smooth particle hydrodynamics algorithm applied to problems with free surfaces ». Computational Particle Mechanics 8, n^o 4 (18 janvier 2021) : 859–92. http://dx.doi.org/10.1007/s40571-020-00374-x.

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AbstractThis paper presents a new Smooth Particle Hydrodynamics computational framework for the solution of inviscid free surface flow problems. The formulation is based on the Total Lagrangian description of a system of first-order conservation laws written in terms of the linear momentum and the Jacobian of the deformation. One of the aims of this paper is to explore the use of Total Lagrangian description in the case of large deformations but without topological changes. In this case, the evaluation of spatial integrals is carried out with respect to the initial undeformed configuration, yielding an extremely efficient formulation where the need for continuous particle neighbouring search is completely circumvented. To guarantee stability from the SPH discretisation point of view, consistently derived Riemann-based numerical dissipation is suitably introduced where global numerical entropy production is demonstrated via a novel technique in terms of the time rate of the Hamiltonian of the system. Since the kernel derivatives presented in this work are fixed in the reference configuration, the non-physical clumping mechanism is completely removed. To fulfil conservation of the global angular momentum, a posteriori (least-squares) projection procedure is introduced. Finally, a wide spectrum of dedicated prototype problems is thoroughly examined. Through these tests, the SPH methodology overcomes by construction a number of persistent numerical drawbacks (e.g. hour-glassing, pressure instability, global conservation and/or completeness issues) commonly found in SPH literature, without resorting to the use of any ad-hoc user-defined artificial stabilisation parameters. Crucially, the overall SPH algorithm yields equal second order of convergence for both velocities and pressure.

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Yonezawa, Ansei, Heisei Yonezawa et Itsuro Kajiwara. « Parameter tuning technique for a model-free vibration control system based on a virtual controlled object ». Mechanical Systems and Signal Processing 165 (février 2022) : 108313. http://dx.doi.org/10.1016/j.ymssp.2021.108313.

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Husna Izzati Osman, Nur Fatihah Mod Omar, Dumitru Vieru et Zulkhibri Ismail. « A Study of MHD Free Convection Flow Past an Infinite Inclined Plate ». Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 92, n^o 1 (5 mars 2022) : 18–27. http://dx.doi.org/10.37934/arfmts.92.1.1827.

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In the present article, we have studied the magnetohydrodynamic (MHD) free convection flow past an infinite inclined plate. In order to explore the effects of velocity, temperature and concentration, Laplace transform technique has been used in this study. This method is adapted to accomplish the analytical solution of governing equation. The impact of various embedded parameter on concentration, velocity and temperature such as chemical reaction, magnetic parameter, radiation and inclination angle has been discussed graphically with numerical results.

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Roko, Abubakar, Aminu Lawal, Aminu B. Muhammad et Abdulgafar Usman. « Improved Parameter-Free 3D Object Retrieval (IP3DOR) System with Hierarchical Clustering ». International Journal of Advanced Networking and Applications 14, n^o 03 (2022) : 5455–63. http://dx.doi.org/10.35444/ijana.2022.14306.

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In content-based 3D object retrieval, searching for a query object in an extensive database is essential. The existing retrieval algorithms adopt the naïve search algorithm in searching for query objects. This approach leads to a high cost of search and retrieval that needs to be addressed. In this research, we introduced an algorithm that calculates each cluster’s representative, that is, a 3D object that has the least dissimilarity on average to each object in the cluster. This is to improve the overall retrieval performance of [1]. We first compute the optimal hierarchical level of the database using a dendrogram, and then calculate the total number of clusters in the database. Afterwards, we calculate the feature descriptor of each cluster. When a user chooses a query object, our system then compares the feature descriptor of the query object with each of the cluster’s representation and search the cluster with the smallest distance to the query, thereby improving the query searching and improving the system. The proposed system was implemented, and the system's performance was evaluated against the benchmark datasets. This revealed that the execution time was reduced by 21% and increased Precision and Recall by 30.7% and 33.1%, respectively. In the future, it is suggested that the technique be improved by incorporating different machine learning algorithms and comparing the results.

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Pinjai, Sirada, et Kanit Mukdasai. « New Delay-Dependent Robust Exponential Stability Criteria of LPD Neutral Systems with Mixed Time-Varying Delays and Nonlinear Perturbations ». Journal of Applied Mathematics 2013 (2013) : 1–18. http://dx.doi.org/10.1155/2013/268905.

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This paper is concerned with the problem of robust exponential stability for linear parameter-dependent (LPD) neutral systems with mixed time-varying delays and nonlinear perturbations. Based on a new parameter-dependent Lyapunov-Krasovskii functional, Leibniz-Newton formula, decomposition technique of coefficient matrix, free-weighting matrices, Cauchy’s inequality, modified version of Jensen’s inequality, model transformation, and linear matrix inequality technique, new delay-dependent robust exponential stability criteria are established in terms of linear matrix inequalities (LMIs). Numerical examples are given to show the effectiveness and less conservativeness of the proposed methods.

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Gani, S. M. O., M. Y. Ali et M. A. Islam. « Effects on Unsteady MHD Flow of a Nanofluid for Free Convection past an Inclined Plate ». Journal of Scientific Research 14, n^o 3 (1 septembre 2022) : 797–812. http://dx.doi.org/10.3329/jsr.v14i3.58301.

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This paper deals with a similarity solution of unsteady magneto hydrodynamics two-dimensional boundary layer flow of a nanofluid for free convection past an inclined plate. Using similarity transformations, the governing equations are reduced into a set of non-linear ordinary differential equations. The transformed dimensionless equations are then solved numerically using the Nachtsheim-Swigert iteration technique and the order Runga-Kutta method. The effects of buoyancy-ratio parameter, Magnetic parameter, Brownian motion parameter, Thermophoresis parameter, Brownian diffusion parameter, unsteadiness, and other driving parameters on the velocity profile, temperature profile, and concentration profile are represented graphically and discussed in detail. The numerical values of several involved parameters on Skin-friction co-efficient, local Nusselt, and Sherwood numbers are presented in tabular form.

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Muhammad Atif, Shahzada, Muhammad Abbas, Umair Rashid et Homan Emadifar. « Stagnation Point Flow of EMHD Micropolar Nanofluid with Mixed Convection and Slip Boundary ». Complexity 2021 (1 juillet 2021) : 1–13. http://dx.doi.org/10.1155/2021/3754922.

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The aim of this numerical research is to study the stagnation point flow of the electrical magnetohydrodynamic micropolar nanofluid with slip conditions past a stretching sheet. The phenomenon of linear thermal radiation, Ohmic and internal heating, has also been considered in the energy equation. The modelled PDEs are converted into ODEs via similarity transformation, and converted ODEs are tackled via the shooting technique. The features of assorted parameters on the axial and angular velocities and energy and concentration fields are sketched. The numerical values of the Sherwood and Nusselt numbers have been computed numerically and displayed in the form of tables. Our analysis shows that the heat transfer rate is decreased as the thermal slip parameter and the diffusion slip parameter are enhanced. The present study illustrates that the energy and concentration distribution are decreased with each of the mass free convection parameter, stagnation parameter, and thermal free convection parameter.

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Gao, Yu, et Zikai Wu. « Controlling the trapping efficiency in a family of scale-free tree networks ». International Journal of Modern Physics B 32, n^o 21 (6 août 2018) : 1850224. http://dx.doi.org/10.1142/s0217979218502247.

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Efficiently controlling the trapping process is very significant in the study of trapping problem in diverse dynamic processes. In this paper, we explore the trapping efficiency on a family of scale-free tree networks with a deep trap positioned at an initial node, which is controlled by three different strategies. In the first technique, the transition probability is modified by an edge weight parameter. In the second method, the transition probability is controlled by a delay parameter. In the third approach, we use the delay parameter and weight parameter simultaneously to control the trapping process. For all the three control methods, the analytical results of average trapping time (ATT) exactly agree with the numerical results. The result of the first control strategy shows that the average trapping time can scale sublinearly, linearly or superlinearly by modifying the weight parameter. The analytic expression of the ATT in the second method shows that the delay parameter can only modify the main coefficient of ATT, but cannot change the dominant behavior of trapping efficiency. The explicit expression of average trapping time when random walk on scale-free tree network is controlled by the third method shows that it is a fine control. We can get desired trapping efficiency by changing the weight parameter and the delay parameter simultaneously. This work provides a better understanding of controlling the trapping process in a family of scale-free tree networks.

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Thipprakmas, Sutasn. « Parameter Design for the Counter-Blanking Process Using the Finite Element Method and the Taguchi Approach ». Key Engineering Materials 443 (juin 2010) : 134–39. http://dx.doi.org/10.4028/www.scientific.net/kem.443.134.

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There is an increasing demand for high quality metal stamped parts. In general, burr formation is the main defect found subsequent to the blanking process. This defect must be strictly removed specifically for consumer products in order to prevent any kind of injury to the operators. Such a removal process results in an increase of the production cost. The unique merit of the counter-blanking process focuses on fabricating the burr-free blanked parts. However, it is difficult to control the numerous process parameters involved in this process in order to achieve the burr-free blanked parts. Thus, this study aims at investigating the process parameter design for the counter-blanking process by means of combining the finite element method (FEM) and statistical analysis techniques, including the Taguchi method and the analysis of variance (ANOVA) techniques. The results indicate that the process parameter of blanking clearance has a major influence on the die-roll formation features of the burr-free blanked part, respectively followed by the punch penetration depth and the same level of influence of the two process parameters of punch and die diameters in the second step. To conclude, this technique could be applied as a tool to achieve good quality of the burr-free blanked parts by optimizing the value of the process parameters and their favorable combinations.

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Vinh, Pham Van, et Le Quang Huy. « Influence of Variable Nonlocal Parameter and Porosity on the Free Vibration Behavior of Functionally Graded Nanoplates ». Shock and Vibration 2021 (14 juillet 2021) : 1–17. http://dx.doi.org/10.1155/2021/1219429.

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This paper studies the influence of the variable nonlocal parameter and porosity on the free vibration behavior of the functionally graded nanoplates with porosity. Four patterns of distribution of the porosity through the thickness direction are considered. The classical nonlocal elasticity theory is modified to take into account the variation of the nonlocal parameter through the thickness of the nanoplates. The governing equations of motion are established using simple first-order shear deformation theory and Hamilton’s principle. The closed-form solution based on Navier’s technique is employed to solve the governing equations of motion of fully simply supported nanoplates. The accuracy of the present algorithm is proved via some comparison studies in some special cases. Then, the effects of the porosity, the variation of the nonlocal parameter, the power-law index, aspect ratio, and the side-to-thickness ratio on the free vibration of nanoscale porous plates are investigated carefully. The numerical results show that the porosity and nonlocal parameter have strong effects on the free vibration behavior of the nanoplates.

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L., Sivakami, Govindarajan A. et E. P. Siva. « Unsteady MHD Free Convective Two Immiscible Fluid Flows in a Vertical Permeable Plate with Heat and Mass Transfer under Chemical Reaction and Heat Source ». International Journal of Engineering & ; Technology 7, n^o 4.10 (2 octobre 2018) : 818. http://dx.doi.org/10.14419/ijet.v7i4.10.26125.

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In this article , the nonlinear Unsteady MHD Free convective Two Immiscible Fluid Flows in a vertical Permeable plate with Heat and Mass Transfer under chemical reaction and Heat source have been studied here. The conservation equations are solved analytically under the boundary conditions by using perturbation technique. The influence of various non dimensional parameters namely, Magnetic parameter, Prandtl number, chemical reaction,, Thermal radiation parameter and Schmidt number are examined on the velocity, Temperature, Concentration fields in detail. It is noted that the velocity is decreased with increasing Heat source under chemical reaction parameter. But increasing suction parameter decreases the velocity

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JAYARAMAN, J., et R. DE LIMA RODRIGUES. « SUSY BREAKING IN CELKA-HUSSIN'S GENERAL 3D MODEL OSCILLATOR HAMILTONIAN AND THE WIGNER PARAMETER ». Modern Physics Letters A 09, n^o 12 (20 avril 1994) : 1047–58. http://dx.doi.org/10.1142/s0217732394000873.

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The free parameter of the generalized 3D SUSY model oscillator Hamiltonian of Celka and Hussin is identified here with the Wigner parameter of a related super-realized general 3D Wigner oscillator system satisfying a super-generalized quantum commutation rule. The super-oscillator technique is then advantageously employed to determine fully a previously only partially given spectrum by Celka and Hussin for their Hamiltonian. The dependence of the spectrum on the Wigner parameter and the consequent occurrence of exceptional SUSY breakings in the model are clearly brought out.

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Muthucumaraswamy, R., et C. S. Lakshmi. « First Order Chemical Reaction Effects on Exponentially Accelerated Vertical Plate with Variable Mass Diffusion in the Presence of Thermal Radiation ». International Journal of Applied Mechanics and Engineering 20, n^o 2 (1 mai 2015) : 329–44. http://dx.doi.org/10.1515/ijame-2015-0022.

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Abstract Effects of transfer of mass and free convection on the flow field of an incompressible viscous fluid past an exponentially accelerated vertical plate with variable surface temperature and mass diffusion are studied. Results for velocity, concentration, temperature are obtained by solving governing equations using the Laplace transform technique. It is observed that the velocity increases with decreasing values of the chemical reaction parameter or radiation parameter. But the trend is just reversed with respect to the time parameter. The skin friction is also studied.

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Marwan S. Jameel. « Three Term Conjugate Gradient Technique and its Global Convergence based on the Zhang, Zhou and Li methods ». Tikrit Journal of Pure Science 27, n^o 2 (30 novembre 2022) : 84–90. http://dx.doi.org/10.25130/tjps.v27i2.72.

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The optimal conjugation coefficient distinguishes conjugate gradient methods such as two-term, three-term, and conditional from other descent methods. A novel conjugation parameter formula is constructed from Zhang, Zhou, and Li's well-known formula to formulate a three-term conjugation gradient method in the unconstrained optimization domain. The conjugation parameter and the third term parameter were constructed by incorporating the Perry conjugation condition into Shanno's memory-free strategy of a conjugate gradient. The approach demonstrated a steeply sloped search direction for each iteration by demonstrating stability, global convergence, and sufficient descent analysis in the presence of a strong Wolf case. The empirical results established that the proposed method is more efficient than Zhang et al.'s techniques. Through the use of a collection of nonlinear mathematical functions.

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MESKELL, C., et J. A. FITZPATRICK. « ERRORS IN PARAMETER ESTIMATES FROM THE FORCE STATE MAPPING TECHNIQUE FOR FREE RESPONSE DUE TO PHASE DISTORTION ». Journal of Sound and Vibration 252, n^o 5 (mai 2002) : 967–74. http://dx.doi.org/10.1006/jsvi.2001.3971.

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Ji, Shi Ming, Ming Sheng Jin, Li Zhang, Qiao Ling Yuan, Xian Zhang et Guo Da Chen. « Magnetorheological Flexible Gasbag Polishing Technique ». Key Engineering Materials 416 (septembre 2009) : 583–87. http://dx.doi.org/10.4028/www.scientific.net/kem.416.583.

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Combining the advantages of rheological behavior of magnetorheological fluid (MRF) and flexibility adjustability of rubber gasbag, a magnetorheological flexible gasbag polishing technique applied to free-form mould is proposed. With the development of robotic gasbag polishing technique, the flexibility of rubber gasbag can be adjusted by three methods of changing its internal pressure controlled through a pressure control unit, its own material property and structural parameter, and the rheological behavior of MRF inside of it in response to the application of an alterable magnetic field. Effect of rheological behavior to the flexibility of rubber gasbag and surface quality of mould is the single most important focus in this paper. The magnetorheological flexible gasbag polishing system is established and rheological behavior of MRF with magnetic field is described. Through polishing experiment focusing on the relationship between the surface roughness and current around electromagnetic coil, it can be obtained that magnetorheological flexible gasbag polishing technique is effective to improve surface quality when increasing current around coil in certain extent.

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Das, Amlan Jyoti, Anjan Kumar Talukdar et Kandarpa Kumar Sarma. « An Adaptive Rayleigh-Laplacian Based MAP Estimation Technique for Despeckling SAR Images using Stationary Wavelet Transform ». International Journal of Applied Evolutionary Computation 4, n^o 4 (octobre 2013) : 88–102. http://dx.doi.org/10.4018/ijaec.2013100106.

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Removal of speckle noise from Synthetic Aperture Radar (SAR) images is an important step before performing any image processing operations on these images. This paper presents a novel Stationary Wavelet Transform (SWT) based technique for the purpose of removing the speckle noise from the SAR returns. Maximum a posteriori probability (MAP) condition which uses a prior knowledge is used to estimate the noise free wavelet coefficients. The proposed MAP estimator is designed for this purpose which uses Rayleigh distribution for modeling the speckle noise and Laplacian distribution for modeling the statistics of the noise free wavelet coefficients. The parameters required for MAP estimator is determined by technique used for parameter estimation after SWT. Moreover an Laplacian – Gaussian based MAP estimator is also applied and the parameter estimation is done using the same method used for the proposed algorithm. For the purpose of enhancing the visual quality and to restore more edge information, a wavelet based resolution enhancement technique is also used after applying the Inverse stationary Wavelet Transform (ISWT), using interpolation technique. The experimental results show that the proposed despeckling algorithm efficiently removes speckle noise from the SAR images and restores the edge information as well.

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Izzati Khalidah Khalid, Nor Fadzillah Mohd Mokhtar et Zarina Bibi Ibrahim. « Control Effect on Rayleigh-Benard Convection in Rotating Nanofluids Layer with Double-Diffusive Coefficients ». CFD Letters 14, n^o 3 (1 avril 2022) : 79–95. http://dx.doi.org/10.37934/cfdl.14.3.7995.

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Rayleigh-Benard convection in rotating nanofluids layer with feedback control and double-diffusive coefficients heated from below is examined. The model for nanofluid includes the mechanism of Brownian motion and thermophoresis. The system is considered for three types of lower-upper boundary conditions, free-free, rigid-free and rigid-rigid. Linear stability analysis based on normal mode technique is employed, the eigenvalue solution is obtained by Galerkin technique and solved by using Maple software. The effects of rotation, feedback control, double-diffusive cofficients and nanofluids parameters have significant impact to the system. Based on the observation, the effect of increasing the value of rotation, feedback control, Dufour parameter and solutal Rayleigh number are observed to stabilize the system. Meanwhile, the effect of increasing the value of Soret parameter, nanofluids Lewis number, nanoparticles concentration Rayleigh number and modified diffusivity ratio are found to destabilize the system. The effect of modified particles density increment in the system is very small and can be neglected. The effects of the parameters in the system are discussed and presented graphically.

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SARMA, D., N. AHMED et H. DEKA. « MHD FREE CONVECTION AND MASS TRANSFER FLOW PAST AN ACCELERATED VERTICAL PLATE WITH CHEMICAL REACTION IN PRESENCE OF RADIATION ». Latin American Applied Research - An international journal 44, n^o 1 (31 janvier 2014) : 1–8. http://dx.doi.org/10.52292/j.laar.2014.412.

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This paper deals with the study of the thermal radiation and chemical reaction effects on an unsteady MHD free convective mass transfer flow past an accelerated infinite vertical plate embedded in a porous medium. The Rosseland approximation is used to describe the radiative heat flux in the energy equation. The dimensionless governing equations of motion are solved by using Laplace transform technique in closed form. Expressions for the velocity, temperature and concentration are obtained. The resulting velocity and temperature profiles as well as the skin-friction, rate of heat and mass transfer are shown graphically for different values of the physical parameters viz., Grashof number, Prandtl number, Schmidt number, Chemical reaction parameter, Radiation parameter, Magnetic parameter and Porosity parameter.

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Daymond, M. R., et M. W. Johnson. « The determination of a stress-free lattice parameter within a stressed material using elastic anisotropy ». Journal of Applied Crystallography 34, n^o 3 (22 mai 2001) : 263–70. http://dx.doi.org/10.1107/s0021889801002497.

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A method for the calculation of a stress-free lattice parameter from the analysis of diffraction data from stressed material is discussed, utilizing the elastic anisotropy of the material. The technique is demonstrated using data obtained during a uniaxial tension test on untextured austenitic (face-centred cubic) steel. The uncertainty in the calculated lattice parameter for various choices of number of diffraction peaks and different number of stress levels available for the calculation is considered. It is shown that when all the data are within the elastic regime, an accurate evaluation of the reference lattice parameter can be made. When some data are in the plastic regime, a more limited evaluation is possible. The use of plots of lattice parameter against Γhkl[= (h2k2+h2l2+k2l2)/(h2+k2+l2)2] as a method for monitoring plasticity as well as freedom from deviatoric stress is demonstrated.

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Gorla, Rama S. R., Ali J. Chamkha et Abdulkareem Aloraier. « Melting heat transfer in a nanofluid flow past a permeable continuous moving surface ». Journal of Naval Architecture and Marine Engineering 8, n^o 2 (14 juillet 2011) : 83–92. http://dx.doi.org/10.3329/jname.v8i2.6830.

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A boundary layer analysis is presented for the warm, laminar nanoliquid flow to a melting surface moving parallel to a uniform free stream. The resulting system of non-linear ordinary differential equations is solved numerically using Runge-Kutta method with shooting techniques. Numerical results are obtained for the velocity, temperature and concentration distributions, as well as the friction factor, local Nusselt number and local Sherwood number for several values of the parameters, namely the velocity ratio parameter, melting parameter and nanofluid parameters. The obtained results are presented graphically and in tabular form and the physical aspects of the problem are discussed.Keywords: Suction/injection; moving surface; nanofluid; boundary layer; shooting technique. doi: http://dx.doi.org/10.3329/jname.v8i2.6830 Journal of Naval Architecture and Marine Engineering 8(2011) 83-92

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Chand, Ramesh, et G. C. Rana. « Double Diffusive Convection in a Layer of Maxwell Viscoelastic Fluid in Porous Medium in the Presence of Soret and Dufour Effects ». Journal of Fluids 2014 (17 juillet 2014) : 1–7. http://dx.doi.org/10.1155/2014/479107.

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Double diffusive convection in a horizontal layer of Maxwell viscoelastic fluid in a porous medium in the presence of temperature gradient (Soret effects) and concentration gradient (Dufour effects) is investigated. For the porous medium Darcy model is considered. A linear stability analysis based upon normal mode technique is used to study the onset of instabilities of the Maxwell viscolastic fluid layer confined between two free-free boundaries. Rayleigh number on the onset of stationary and oscillatory convection has been derived and graphs have been plotted to study the effects of the Dufour parameter, Soret parameter, Lewis number, and solutal Rayleigh number on stationary convection.

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Bejawada, Shankar Goud, Wasim Jamshed, Rabia Safdar, Yanala Dharmendar Reddy, Meznah M. Alanazi, Heba Y. Zahran et Mohamed R. Eid. « Chemical Reactive and Viscous Dissipative Flow of Magneto Nanofluid via Natural Convection by Employing Galerkin Finite Element Technique ». Coatings 12, n^o 2 (26 janvier 2022) : 151. http://dx.doi.org/10.3390/coatings12020151.

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A numerical study of chemically reactive effects on Magnetohydrodynamics (MHD) free convective unsteady flowing over an inclined plate in a porousness material in the existence of viscous dissipation was studied. The nondimensional principal equations are time dependent coupled and non-linear partial differential equations (PDEs) are solved by the efficacy finite element method (FEM). As well, the computational relationships of speed, energy, and concentricity in the form of Galerkin finite element were obtained. Calculations are achieved with a wide range of key flow parameters, namely, the angle of inclination (α), permeability parameter k, magnetic parameter (M), buoyancy ratio parameter (N), Schmidt number (Sc), Eckert number (Ec), Prandtl number (Pr), chemical factor (Kr) on speed, and concentricity and temperature fields are examined in detail with the assistance of diagrams.

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Ficquet, X., Christopher E. Truman et David John Smith. « Measurement of Residual Stress in an A533B Ferritic Steel Plate Containing a Repair Weld ». Materials Science Forum 524-525 (septembre 2006) : 653–58. http://dx.doi.org/10.4028/www.scientific.net/msf.524-525.653.

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The paper presents the results of residual stress measurements on a ferritic steel plate containing a repair weld. The repair was considered representative of that found in the secondary circuit piping in power plant. The paper primarily uses the deep hole drilling (DHD) technique, but compares results found by this technique with those obtained using neutron diffraction. Both sets of measurements confirmed that highly tensile residual stresses exist in the repair weld. The two measurement techniques produced results that were in acceptable agreement, but the neutron diffraction results were consistently higher than the deep hole drilling results. It was thought this was due to the use of a constant stress-free lattice parameter d0 .

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Xiao, Heng, Wei-Hao Yan, Lin Zhan et Si-Yu Wang. « Parameter-free strain-energy function which automatically and accurately matches benchmark test data for soft elastic solids ». Multidiscipline Modeling in Materials and Structures 18, n^o 1 (17 janvier 2022) : 129–41. http://dx.doi.org/10.1108/mmms-11-2021-0182.

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PurposeA new and explicit form of the elastic strain-energy function for modeling large strain elastic responses of soft solids is constructed based on Hencky's logarithmic strain tensor.Design/methodology/approachWell-designed invariants of the Hencky strain are introduced for characterizing deformation modes and, furthermore, a new interpolating technique is proposed for combining piecewise splines into a single smooth function.FindingsWith this new form and this new technique, objectives in three respects may be achieved for the first time.Originality/valueFirst, no adjustable parameters need to be treated. Second, large strain responses for three benchmark modes are derivable in a decoupled sense without involving strongly nonlinear coupling effects. Finally, large strain data may be automatically and accurately matched for three benchmark modes, including uniaxial, equi-biaxial and plane-strain extension. Numerical examples are presented and compared with usual approaches.

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Gao, Jing, Jian Cao et Yueting Yang. « A Derivative-Free Trust Region Algorithm with Nonmonotone Filter Technique for Bound Constrained Optimization ». Mathematical Problems in Engineering 2018 (23 octobre 2018) : 1–13. http://dx.doi.org/10.1155/2018/5049027.

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We propose a derivative-free trust region algorithm with a nonmonotone filter technique for bound constrained optimization. The derivative-free strategy is applied for special minimization functions in which derivatives are not all available. A nonmonotone filter technique ensures not only the trust region feature but also the global convergence under reasonable assumptions. Numerical experiments demonstrate that the new algorithm is effective for bound constrained optimization. Locally, optimal parameters with respect to overall computational time on a set of test problems are identified. The performance of the best choice of parameter values obtained by the algorithm we presented which differs from traditionally used values indicates that the algorithm proposed in this paper has a certain advantage for the nondifferentiable optimization problems.

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Marneni, Narahari. « An Exact Solution of Unsteady MHD Free Convection Flow of a Radiating Gas Past an Infinite Inclined Isothermal Plate ». Applied Mechanics and Materials 110-116 (octobre 2011) : 2228–33. http://dx.doi.org/10.4028/www.scientific.net/amm.110-116.2228.

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The effect of thermal radiation on unsteady magnetohydrodynamic free convection flow of an optically thin gray gas past an infinite inclined plate with constant temperature has been investigated. The governing coupled partial differential equations are solved analytically using the Laplace transform technique. The dimensionless velocity and temperature profiles are shown in graphs and the numerical values of the non-dimensional skin-friction and Nusselt number are presented in tables. The influence of the system parameters such asPrandtl number, inclination angle, magnetic field parameter, Grashof number, radiation parameter and time on flow fields have been discussed in detail. The results indicate that the inclination angle, magnetic field parameter and radiation parameter effects were to decrease the fluid velocity along an inclined plate.

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Chen, Jun, Xiaohan Wan et Quanquan Guo. « Monitoring of stress variation of strands in prestressed concrete by second harmonic generation measurements based on piezoelectric sensors ». Smart Materials and Structures 31, n^o 1 (19 novembre 2021) : 015004. http://dx.doi.org/10.1088/1361-665x/ac36e1.

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Abstract The stress loss of prestressed concrete may cause the ultimate failure of structures and the monitoring of stress variation of prestressed structures is therefore important to ensure the service safety. This paper developed a nondestructive evaluation method of nonlinear ultrasonic second harmonic generation (SHG) based on piezoelectric (PZT) sensors and applied for the distinction of different stress level of post-tensioned steel strands in concrete. The nonlinear ultrasonic behavior of both free strand and embedded strand having different length is studied with the developed SHG technique and a defined nonlinear parameter is introduced in SHG experiments to correlate with the tension stress in the strand. It is found that the nonlinear parameter has a negative correlation with the increasing stress of strand in both free and embedded case, indicating the nonlinear ultrasonic behavior is getting weak corresponding to the increasing contact force among strand wires. In addition, the decreasing ratio of nonlinear parameter is very close to each other regardless of the length of steel strand, indicating the possibility of replacing the large-scale on-site testing with scaled down samples in laboratory. The experimental results of this research demonstrate that the SHG technique based on PZT sensors could be useful for the stress monitoring of prestressed reinforced concrete with consideration of the relatively high sensitivity of nonlinear parameter to the variation of contact force of strand wires.

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Putra, Adam Sukma, Wahyu Srigutomo, Yuant Tiandho, Herlin Tarigan et Yanti Yanti. « An Application of Inversion Technique to 1-Dimensional Gravity Data in Bayesian Framework using Monte Carlo, Metropolis, and Simulated Annealing Algorithm ». Indonesian Journal of Physics 30, n^o 1 (9 janvier 2019) : 1–5. http://dx.doi.org/10.5614/itb.ijp.2019.30.1.1.

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The purpose of this paper is to present a simulation to the inversion methods applied to geophysical exploration. Anapplication of Monte-Carlo, Metropolis, and Simulated Annealing techniques to 1-Dimensional gravity inversion inBayesian framework has been studied. Differences between these methods are observed in both single parameterinversion and simultaneous multi parameter inversion. After selecting the best inversion strategy from the three methods,a further investigation was investigated. Multi parameter inversion for two anomalies is simultaneously carried out andresults are observed. The synthetical data of GRAV2DC free source were used instead of observed data.

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Muthucumaraswamy, R., et B. Janakiraman. « MHD and radiation effects on moving isothermal vertical plate with variable mass diffusion ». Theoretical and Applied Mechanics 33, n^o 1 (2006) : 17–29. http://dx.doi.org/10.2298/tam0601017m.

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An analysis is performed to study the effects of thermal radiation on unsteady free convective flow over a moving vertical plate with mass transfer in the presence of magnetic field. The fluid considered here is a gray, absorbing-emitting radiation but a non- scattering medium. The plate temperature is raised to T 0 and the concentration level near the plate is also raised linearly with time. The dimensionless governing equations are solved using the Laplace transform technique. The velocity, temperature and concentration are studied for different parameters like the magnetic field parameter, radiation parameter, thermal Grashof number, mass Grashof number and time. It is observed that the velocity decreases with increasing magnetic field parameter or radiation parameter. .

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Pande, Kanupriya, Jeffrey J. Donatelli, Erik Malmerberg, Lutz Foucar, Christoph Bostedt, Ilme Schlichting et Petrus H. Zwart. « Ab initio structure determination from experimental fluctuation X-ray scattering data ». Proceedings of the National Academy of Sciences 115, n^o 46 (29 octobre 2018) : 11772–77. http://dx.doi.org/10.1073/pnas.1812064115.

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Fluctuation X-ray scattering (FXS) is an emerging experimental technique in which X-ray solution scattering data are collected from particles in solution using ultrashort X-ray exposures generated by a free-electron laser (FEL). FXS experiments overcome the low data-to-parameter ratios associated with traditional solution scattering measurements by providing several orders of magnitude more information in the final processed data. Here we demonstrate the practical feasibility of FEL-based FXS on a biological multiple-particle system and describe data-processing techniques required to extract robust FXS data and significantly reduce the required number of snapshots needed by introducing an iterative noise-filtering technique. We showcase a successful ab initio electron density reconstruction from such an experiment, studying the Paramecium bursaria Chlorella virus (PBCV-1).

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Pattnayak, Hadibandhu, et Rojali Mohapatra. « Dufour and radiation effect on MHD boundary layer flow past a wedge through porous medium with heat source and chemical reaction ». JOURNAL OF ADVANCES IN MATHEMATICS 11, n^o 4 (16 septembre 2015) : 5094–107. http://dx.doi.org/10.24297/jam.v11i4.1259.

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Magnetohydrodynamics (MHD) boundary layer flow past a wedge with the influence of thermal radiation, heat generation and chemical reaction has been analyzed in the present study. This model used for the momentum, temperature and concentration fields. The principal governing equations is based on the velocity in a nanofluid and with a parallel free stream velocity and surface temperature and concentration. The governing nonlinear boundary layer equations for momentum, thermal energy and concentration are transformed to a system of nonlinear ordinary coupled differential equations by using suitable similarity transformation with fitting boundary conditions. The transmuted model is shown to be controlled by a number of thermo-physical parameters, viz. the magnetic parameter, buoyancy parameter, radiation conduction parameter, heat generation parameter, Porosity parameter, Dufour number, Prandtl number, Lewis number, Brownian motion parameter, thermophoresis parameter, chemical reaction parameter and pressure gradient parameter. Numerical elucidations are obtained with the legendary Nactsheim-Swigert shooting technique together with RungeKutta six order iteration schemes.

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Halilu, Abubakar, Mohammed Waziri et Ibrahim Yusuf. « Efficient matrix-free direction method with line search for solving large-scale system of nonlinear equations ». Yugoslav Journal of Operations Research 30, n^o 4 (2020) : 399–412. http://dx.doi.org/10.2298/yjor160515005h.

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We proposed a matrix-free direction with an inexact line search technique to solve system of nonlinear equations by using double direction approach. In this article, we approximated the Jacobian matrix by appropriately constructed matrix-free method via acceleration parameter. The global convergence of our method is established under mild conditions. Numerical comparisons reported in this paper are based on a set of large-scale test problems and show that the proposed method is efficient for large-scale problems.

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Zhang, Han, Huawei Fan, Yao Du, Liang Wang et Xingang Wang. « Anticipating measure synchronization in coupled Hamiltonian systems with machine learning ». Chaos : An Interdisciplinary Journal of Nonlinear Science 32, n^o 8 (août 2022) : 083136. http://dx.doi.org/10.1063/5.0093663.

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A model-free approach is proposed for anticipating the occurrence of measure synchronization in coupled Hamiltonian systems. Specifically, by the technique of parameter-aware reservoir computing in machine learning, we demonstrate that the machine trained by the time series of coupled Hamiltonian systems at a handful of coupling parameters is able to predict accurately not only the critical coupling for the occurrence of measure synchronization, but also the variation of the system order parameters around the transition point. The capability of the model-free technique in anticipating measure synchronization is exemplified in Hamiltonian systems of two coupled oscillators and also in a Hamiltonian system of three globally coupled oscillators where partial synchronization arises. The studies pave a way to the model-free, data-driven analysis of measure synchronization in large-size Hamiltonian systems.

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Y H, Gangadharaiah. « Variable Viscosity Effects on Penetrative Convection in a Fluid Layer ». Mapana - Journal of Sciences 13, n^o 3 (28 juillet 2017) : 51–65. http://dx.doi.org/10.12723/mjs.30.4.

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The effect of variable viscosity on the onset of penetrative convection simulated via internal heating in a fluid layer. The upper surface of a fluid layer is assumed to be deformably free and dependence of viscosity is assumed to be exponential. The resulting eigen value problem is solved using a regular perturbation technique with wave number a as a perturbation parameter. The viscosity parameter, surface deformation and the presence of internal heat source play a decisive role on the stability characteristics of the system.

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Singh, Padam, et Manoj Kumar. « Free Convection in Heat Transfer Flow over a Moving Sheet in Alumina Water Nanofluid ». Journal of Engineering 2014 (2014) : 1–6. http://dx.doi.org/10.1155/2014/137426.

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The present paper deals with study of free convection in two-dimensional magnetohydrodynamic (MHD) boundary layer flow of an incompressible, viscous, electrically conducting, and steady nanofluid. The governing equations representing fluid flow are transformed into a set of simultaneous ordinary differential equations by using appropriate similarity transformation. The equations thus obtained have been solved numerically using adaptive Runge-Kutta method with shooting technique. The effects of physical parameters like magnetic parameter, temperature buoyancy parameter on relative velocity and temperature distribution profile, shear stress profile, and temperature gradient profile were depicted graphically and analyzed. Significant changes were observed due to these parameters in velocity and temperature profiles.

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Xia, Yingzhi, Hui Li, Zhezhe Fan et Jiyong Xiao. « Modal Parameter Identification Based on Hilbert Vibration Decomposition in Vibration Stability of Bridge Structures ». Advances in Civil Engineering 2021 (25 février 2021) : 1–9. http://dx.doi.org/10.1155/2021/6688686.

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Modal parameters are important parameters for the dynamic response analysis of structures. An output-only modal parameter identification technique based on Hilbert Vibration Decomposition (HVD) is developed herein for structural modal parameter identification to (1) obtain the Free Decay Response (FDR) of a structure through free vibration or ambient vibration tests, (2) decompose the FDR into modal responses using HVD, and (3) calculate the instantaneous frequencies and instantaneous damping ratios of the modal responses to obtain the modal frequencies and modal damping ratios. A series of numerical examples are examined to demonstrate the efficiency and highlight the superiorities of the proposed method relative to the empirical model decomposition-based (EMD-based) method. The robustness of the proposed method to noises is also investigated and proved to be positive effect. The proposed method is proved to be efficient in modal parameter identification for both linear and nonlinear systems, with better frequency resolution, and it can be applied to systems with closely spaced modes and low-energy mode.

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