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1
MJIDILA, Ahmed, Salah Eddine JALAL, Lahbib BOUSSHINE, and Zakaria EL LASKAOUI. "Nodal Integration Technique in Meshless Method." IOSR Journal of Mechanical and Civil Engineering 11, no. 1 (2014): 18–26. http://dx.doi.org/10.9790/1684-11141826.
2
FENG, HUI, XIANGYANG CUI, and GUANGYAO LI. "STATIC AND DYNAMIC ANALYSIS OF TIMOSHENKO BEAM USING NODAL INTEGRATION TECHNIQUE." International Journal of Applied Mechanics 04, no. 04 (December 2012): 1250045. http://dx.doi.org/10.1142/s1758825112500457.
Анотація:
In this paper, a nodal integration method (NIM) is presented to deal with the static and dynamic problems of Timoshenko beam. In the present method, linear-shape functions are employed to approximate the displacement field, and smoothing domains based on the nodes are further formed for computing the stiffness matrix. Through a smoothing operation, the shear locking is effectively avoided and the computation gets much simpler. For static problems, the upper bounds for a set of benchmark examples are obtained by nodal integration. For dynamic problems, while keeping the shear stiffness matrix the same as NIM, integration based on elements is adopted to construct the bending stiffness matrix to improve the stability and diminish singular modes caused by pure nodal integration. Results computed in this way prove to be much better than pure nodal integration method for free vibration and forced vibration problems. Numerical examples indicate that very accurate results can be obtained when a reasonable number of nodes is used. Both computational efficiency and accuracy are achieved by above formulations.
3
Greco, Francesco, Domenico Umbrello, Serena Di Renzo, Luigino Filice, I. Alfaro, and E. Cueto. "Application of the Nodal Integrated Finite Element Method to Cutting: a Preliminary Comparison with the “Traditional” FEM Approach." Advanced Materials Research 223 (April 2011): 172–81. http://dx.doi.org/10.4028/www.scientific.net/amr.223.172.
Анотація:
FEM implicit formulation shows specific limitations in processes such as cutting, where large deformation results in a heavy mesh distortion. Powerful rezoning-remeshing algorithms strongly reduce the effects of such a limitation but the computational times are significantly increased and additional errors are introduced. Nodal Integration is a recently introduced technique that allows finite element method to provide more reliable results when mesh becomes distorted in traditional FEMs. Furthermore, volumetric locking phenomenon seems to be avoided by using this integration technique instead of other methods, such as the coupled formulations. In this paper, a comparison between a “classical” FEM simulation and the Nodal Integration one is carried out taking into account a simple orthogonal cutting process.
4
Patel, Bhavana S. S., Babu K. S. Narayan, and Katta Venkataramana. "Strategy for refinement of nodal densities and integration cells in EFG technique." Structural Engineering and Mechanics 59, no. 5 (September 10, 2016): 901–20. http://dx.doi.org/10.12989/sem.2016.59.5.901.
5
Liu, G. R., G. Y. Zhang, Y. Y. Wang, Z. H. Zhong, G. Y. Li, and X. Han. "A nodal integration technique for meshfree radial point interpolation method (NI-RPIM)." International Journal of Solids and Structures 44, no. 11-12 (June 2007): 3840–60. http://dx.doi.org/10.1016/j.ijsolstr.2006.10.025.
6
Canales, Diego, Adrien Leygue, Francisco Chinesta, Elias Cueto, Eric Feulvarch, Jean Michel Bergheau, Yannick Vincent, and Frederic Boitout. "Efficient Updated-Lagrangian Simulations in Forming Processes." Key Engineering Materials 651-653 (July 2015): 1294–300. http://dx.doi.org/10.4028/www.scientific.net/kem.651-653.1294.
Анотація:
A new efficient updated-Lagrangian strategy for numerical simulations of material forming processes is presented in this work. The basic ingredients are the in-plane-out-of-plane PGD-based decomposition and the use of a robust numerical integration technique (the Stabilized Conforming Nodal Integration). This strategy is of general purpose, although it is especially well suited for plateshape geometries. This paper is devoted to show the feasibility of the technique through some simple numerical examples.
7
Horst, Vernon D., Hetal D. Patel, and Stan C. Hewlett. "Robotic Transhiatal Esophagectomy in a Community Hospital: Evolution of Technique." American Surgeon 82, no. 8 (August 2016): 730–32. http://dx.doi.org/10.1177/000313481608200832.
Анотація:
Esophageal cancer is an uncommon but highly lethal disease. Surgical resection is the gold standard of treatment for early-stage disease. Traditional surgical approach entailed significant convalescence, hospital stay, and morbidity and mortality. Transhiatal esophagectomy (THE) involves blind dissection of the esophagus with minimal mediastinal lymphadenectomy. Integration of robotic surgery is an alternate platform for minimally invasive approach while maintaining safety and following oncologic principles. We review our technique for minimally invasive THE using robotic technology, demonstrating the safety and efficacy of robotic technology surgery. We present a retrospective review of a single surgeon's data of patients treated with robotic-assisted THE, with a chart review to evaluate pathology, adequacy of surgical resection, nodal harvest, and perioperative course. Robotic THE (rTHE) shows promise as a valid option for esophageal resection, including premalignant and advanced stages of cancer. Adequate transhiatal mediastinal nodal resection can be performed with the robot.
8
Zhou, J. X., J. B. Wen, H. Y. Zhang, and L. Zhang. "A nodal integration and post-processing technique based on Voronoi diagram for Galerkin meshless methods." Computer Methods in Applied Mechanics and Engineering 192, no. 35-36 (August 2003): 3831–43. http://dx.doi.org/10.1016/s0045-7825(03)00376-1.
9
CUI, X. Y., S. LIN, and G. Y. LI. "NODAL INTEGRATION THIN PLATE FORMULATION USING LINEAR INTERPOLATION AND TRIANGULAR CELLS." International Journal of Computational Methods 08, no. 04 (November 20, 2011): 813–24. http://dx.doi.org/10.1142/s0219876211002848.
Анотація:
This paper presents a thin plate formulation with nodal integration for bending analysis using three-node triangular cells and linear interpolation functions. The formulation was based on the classic thin plate theory, in which only deflection field was required and dealt with as the field variables. They were assumed to be piecewisely linear and expressed using a set of three-node triangular cells. Based on each node, the integration domain has been further derived, where the curvature in the domain was computed using a gradient smoothing technique (GST). As a result, the curvature in each integration domain is a constant whereby the deflection is compatible in the whole problem domain. The generalized smoothed Galerkin weak form is then used to create the discretized system equations where the system stiffness is obtained using simple summation operation. The essential rotational boundary conditions are imposed in the process of constructing the curvature field in conjunction with imposing the translational boundary conditions in the same way as undertaken in the standard FEM. A number of numerical examples were studied using the present formulation, including both static and free vibration analyses. The numerical results were compared with the reference ones together with those shown in the state-of-art literatures published. Very good accuracy has been achieved using the present method.
10
Darbani, Mohsen. "The Meshfree Finite Element Method for Fluids with Large Deformations." Defect and Diffusion Forum 326-328 (April 2012): 176–80. http://dx.doi.org/10.4028/www.scientific.net/ddf.326-328.176.
Анотація:
The shallow water equations (SWE) is often simulated by using Eulerian descriptions. These phenomena may give rise to strong gradients and lead to large distortion of grids meshes. Hence classical finite elements methods may fall in simulating such problems. In this paper we present a meshless method, based on the natural element nethod (NEM). In a geometrical domain of a cloud of nodes, NEM uses the Voronoi cells and then its dual, namely Delaunay triangulation. Its main advantage lies in shape function of the natural neighbour interpolation, such that the position of natural neighbours is enough to its construction. To avoid the nonlinear term, the time material derivative term is discretized by a Lagrangian procedure. We also used an appropriate nodal integration technique to estimate integrals related to the diffusion, pressure and Coriolis terms because NEM shape functions are not polynomials and they are rational. For the diffusion term, the method of stabilized conforming nodal integration (SCNI) is proposed while for pressure and Coriolis terms a geometrical method will transform the integration over the cells domain to the integration over the edges. The method was successfully used to simulate dam-break flows by solving the fully 2D shallow water equations (SWE) by using an implicit scheme under a transient flow.
11
Du, Yi Xian, Jin Run Hu, and Yi Zhang. "An Adaptive Element-Free Galerkin Method Based on the Strain Energy Density." Advanced Materials Research 677 (March 2013): 225–29. http://dx.doi.org/10.4028/www.scientific.net/amr.677.225.
Анотація:
In practical study, an adaptive procedure based on the gradient of the strain energy density is developed for element-free Galerkin method using moving least-squares (MLS) approximation and global Galerkin formulation require a background mesh for domain integration. It comprises nodal strain energy density and a local domain refinement technique. The numerical experiments in this paper show that this adaptive element-free Galerkin method is simple, effective and efficient.
12
Rathod, H. T., Md Shafiqul Islam, Bharath Rathod, and K. Sugantha Devi. "Finit element solution of Poisson Equation over Polygonal Domains using a novel auto mesh generation technique and an explicit integration scheme for linear convex quadrilaterals of cubic order Serendipity and Lagrange families." International Journal Of Engineering And Computer Science 7, no. 01 (January 6, 2018): 23329–482. http://dx.doi.org/10.18535/ijecs/v7i1.01.
Анотація:
This paper presents an explicit integration scheme to compute the stiffness matrix of twelve node and sixteen node linear convex quadrilateral finite elements of Serendipity and Lagrange families using an explicit integration scheme and discretisation of polygonal domain by such finite elements using a novel auto mesh generation technique, In finite element analysis, the boundary value problems governed by second order linear partial differential equations, the element stiffness matrices are expressed as integrals of the product of global derivatives over the linear convex quadrilateral region. These matrices can be shown to depend on the material properties matrices and the matrix of integrals with integrands as rational functions with polynomial numerator and the linear denominator (4+) in the bivariates over a 2-square (-1 ) with the nodes on the boundary and in the interior of this simple domain. The finite elements up to cubic order have nodes only on the boundary for Serendipity family and the finite elements with boundary as well as some interior nodes belong to the Lagrange family. The first order element is the bilinear convex quadrilateral finite element which is an exception and it belongs to both the families. We have for the present ,the cubic order finite elements which havee 12 boundary nodes at the nodal coordinates {(-1,-1),(1,-1),(1,1),(-1,1),(-1/3,-1), (1/3,-1),(1,-1/3),(1,1/3),(1/3,1),(-1/3,1),(-1,1/3),(-1,-1/3)} and the four interoior nodal coordinates at the points (-1/3,-1/3),(1/3,-1/3),(1/3,1/3),(-1/3,1/3)} in the local parametric space ( In this paper, we have computed the integrals of local derivative products with linear denominator (4+) in exact forms using the symbolic mathematics capabilities of MATLAB. The proposed explicit finite element integration scheme can be then applied to solve boundary value problems in continuum mechanics over convex polygonal domains. We have also developed a novel auto mesh generation technique of all 12-node and 16-node linear(straight edge) convex quadrilaterals for a polygonal domain which provides the nodal coordinates and the element connectivity. We have used the explicit integration scheme and this novel auto mesh generation technique to solve the Poisson equation u ,where u is an unknown physical variable and in with Dirichlet boundary conditions over the convex polygonal domain.
13
Belinha, J., J. M. C. Azevedo, L. M. J. S. Dinis, and R. M. Natal Jorge. "The Natural Neighbor Radial Point Interpolation Method in Computational Fracture Mechanics: A 2D Preliminary Study." International Journal of Computational Methods 14, no. 04 (April 18, 2017): 1750045. http://dx.doi.org/10.1142/s0219876217500451.
Анотація:
In this work, the natural neighbor radial point interpolation method (NNRPIM) is extended to the numeric analysis of crack propagation problems. Here, the advanced discretization meshless technique is combined with a linear elastic crack growth algorithm. The algorithm simulates the crack propagation by displacing iteratively the crack tip, which consequently requires a local remeshing. In each iteration, it is estimated the stress state in the crack tip and afterwards the direction of the crack propagation is obtained considering the maximum circumferential stress criterion.The required local remeshing does not represent a numeric difficulty for the NNRPIM. The main advantage of the NNRPIM is its capability to fully discretize the problem domain using only an unstructured nodal distribution. Being a truly meshless method, the NNRPIM is able to define autonomously the nodal connectivity and the background integration mesh.The classic NNRPIM formulation permits to enforce the nodal connectivity by means of two kind of influence-cells: first degree influence-cells or second degree influence-cells. This work investigates the influence of the nodal connectivity on the simulated crack propagation path. Thus, demanding benchmark crack propagation examples are studied and the obtained results are compared with reference solutions available in the literature.
14
Jannesari, Zahra, and Mehdi Tatari. "A Meshfree Technique for Numerical Simulation of Reaction-Diffusion Systems in Developmental Biology." Advances in Applied Mathematics and Mechanics 9, no. 5 (July 11, 2017): 1225–49. http://dx.doi.org/10.4208/aamm.2015.m1085.
Анотація:
AbstractIn this work, element free Galerkin (EFG) method is posed for solving nonlinear, reaction-diffusion systems which are often employed in mathematical modeling in developmental biology. A predicator-corrector scheme is applied, to avoid directly solving of coupled nonlinear systems. The EFG method employs the moving least squares (MLS) approximation to construct shape functions. This method uses only a set of nodal points and a geometrical description of the body to discretize the governing equation. No mesh in the classical sense is needed. However a background mesh is used for integration purpose. Numerical solutions for two cases of interest, the Schnakenberg model and the Gierer-Meinhardt model, in various regions is presented to demonstrate the effects of various domain geometries on the resulting biological patterns.
15
Poirier, D., and M. Salcudean. "On Numerical Methods Used in Mathematical Modeling of Phase Change in Liquid Metals." Journal of Heat Transfer 110, no. 3 (August 1, 1988): 562–70. http://dx.doi.org/10.1115/1.3250529.
Анотація:
The work presents an analysis and comparative evaluation of different methods used for the numerical solution of heat conduction with phase change problems. Both freezing (melting) water as well as solidifying liquid metal problems are examined. Emphasis is placed on weak formulations as they tend to be simple to program and easily implemented in existing single-phase codes. A new method based on the apparent capacity technique is proposed. In this technique an “effective capacity” is computed, based on the integration of temperature profiles over the nodal volumes. This method shows significantly better performance when compared with other methods for the numerical analysis of solidifying metals.
16
ALI, FARHAD, and M. A. KASSAR. "HYPERBOLIC CONSERVATION LAWS HAVING SOURCE TERMS AND DONOR CELL DIFFERENCING." International Journal of Modern Physics C 05, no. 03 (June 1994): 519–36. http://dx.doi.org/10.1142/s0129183194000702.
Анотація:
Modifications in the integration of the source terms in hyperbolic conservation laws such as those governing combustion, detonation and radiative transport, with a first order upwind differencing technique are proposed and analysed. The von Neuman stability and phase error analysis for a linear scalar equation, together with a few test problems is presented in order to compare the performance of the resulting variants of the donor cell scheme. It is established that when the source term is integrated using higher order formulae, the resulting scheme gives better resolution and has better stability limit and phase accuracy, compared to the standard single nodal value replacement. It is shown that integration by the trapezoidal rule gives sufficient accuracy and further improvement may not necessarily be achieved using better methods, such as the Simpson’s rule.
17
Ghoreishi, Farideh, and Elena Farahbakhsh-Tooli. "The Laguerre Collocation Method for Third Kind Integral Equations on Unbounded Domains." Computational Methods in Applied Mathematics 16, no. 2 (April 1, 2016): 245–56. http://dx.doi.org/10.1515/cmam-2015-0038.
Анотація:
AbstractThe aim of this paper is to approximate the solution of a class of integral equations of the third kind on an unbounded domain. For computing such approximation, the collocation method based on the generalized Laguerre abscissas is considered. In this method, the unknown function is interpolated at the nodal points ${\lbrace t_i\rbrace _{i=1}^{n+1}}$, where ${\lbrace t_i\rbrace _{i=1}^{n}}$ are the zeros of generalized Laguerre polynomials and ${t_{n+1}=4n}$. Then, the given equation is transformed to the Fredholm integral equation of the second kind. In the sequel, according to the integration interval, we apply the Gauss–Laguerre collocation method on the interval ${[0,\infty )}$ by using the given nodal points. Therefore, the solution of the third kind integral equation is reduced to the solution of a system of linear equations. Convergence analysis of the method in some Sobolev-type space is studied. Illustrative examples are included to demonstrate the validity and applicability of the technique.
18
Binesh, S. M., and A. Gholampour. "Mesh-Free Lower Bound Limit Analysis." International Journal of Computational Methods 12, no. 01 (January 23, 2015): 1350105. http://dx.doi.org/10.1142/s0219876213501053.
Анотація:
A novel numerical approach is developed for computing lower bound limit load in soil mechanics problems under plane strain condition. In the presented technique, there is no need to mesh in the traditional sense, and a lower bound solution is obtained. To develop the lower bound optimization problem, a statically admissible stress field is constructed by Shepard's shape functions in conjunction with the stabilized nodal integration scheme. The linearized Mohr–Coulomb criterion is adopted to satisfy the plastic admissibility of the generated stress field. The obtained optimization problem with a considerable reduced number of constraints has been solved by the linear programming technique. Based on the derived formulations, a computer code has been developed and the accuracy and efficiency of proposed method is demonstrated by solving some examples at the end of the paper.
19
Shao, Weidong, and Jun Li. "An Absorbing Boundary Condition Based on Perfectly Matched Layer Technique Combined with Discontinuous Galerkin Boltzmann Method for Low Mach Number Flow Noise." Journal of Theoretical and Computational Acoustics 26, no. 04 (December 2018): 1850011. http://dx.doi.org/10.1142/s2591728518500111.
Анотація:
For flow noise simulations, the nonreflecting boundary condition (NRBC) is significant to confine the computational domain to a small domain. Lattice Boltzmann method (LBM) has advantages for noise because of its low dissipation, but is limited to the uniform grid. In this paper, an absorbing boundary condition (ABC) based on perfectly matched layer (PML) technique is introduced to LBM. Then PML stability is analyzed and a new strategy is developed to achieve robustness. Invoking the decoupling time integration, the underlying equation for streaming is solved with the nodal discontinuous Galerkin method. Benchmark acoustic problems were used to demonstrate the PML absorption. Moreover, PML parameters, long time behavior and inhomogeneous pseudo mean flow are discussed. The methodology appears to work very well and would be hoped for practical flow noise computation.
20
Shabana, A. "Dynamics of Inertia-Variant Flexible Systems Using Experimentally Identified Parameters." Journal of Mechanisms, Transmissions, and Automation in Design 108, no. 3 (September 1, 1986): 358–66. http://dx.doi.org/10.1115/1.3258740.
Анотація:
In this investigation modal parameters (frequency, damping, and mode shapes) which are determined experimentally using parameter estimation techniques are employed to simulate and predict the dynamic behavior of flexible multibody systems which consist of interconnected rigid and flexible components. The system differential equations of motion and algebraic constraint equations describing mechanical joints in the system are first identified using analytical techniques. Dynamic parameters such as mass, damping, and stiffness coefficients that appear in the system differential equations are then identified using a set of experimentally measured data. Mode shapes which are the result of the experimental identification are used to write the physical elastic coordinates of selected nodal points on the flexible body in terms of a reduced set of modal coordinates. The nonlinear differential and algebraic constraint equations are then written in terms of mixed sets of coupled reference and modal coordinates. These equations are integrated numerically using a direct numerical integration technique coupled with Newton–Raphson type iterations in order to check on constraint violations. The formulation developed is numerically exemplified using a three-dimensional dune buggy vehicle model.
21
Huang, Yuan Mao, and Yung-Shane Liaw. "The Impact of Sliding Blades in a Rotary Compressor." Journal of Mechanical Design 123, no. 4 (April 1, 1999): 583–89. http://dx.doi.org/10.1115/1.1416150.
Анотація:
The purpose of this study was to analyze the impact of blades with slots in a rotary compressor. The equations for contact forces were derived from Newton’s law. Updated moving Lagrangian descriptions with the hybrid technique and the Newark time integration method were used to determine the nodal displacement vectors. The finite element method was used to analyze the contact forces and the stresses of blades. The maximum blade contact force of 2.3 KN was larger than the maximum static force of 1 KN. The maximum blade impact Von Mises stress of 12.3 Mpa that occurred at the contact point was greater than the previous calculated static stress of 5.15 Mpa. Hence, the impact effect was significant. Experimental modal analysis was also used to determine the first and second natural frequencies of blades.
22
Isobe, Daigoro, Daisaku Imaizumi, Youichi Chikugo, and Shunsuke Sato. "A Parallel Solution Scheme for Inverse Dynamics and its Application in Feed-forward Control of Link Mechanisms." Journal of Robotics and Mechatronics 15, no. 1 (February 20, 2003): 1–7. http://dx.doi.org/10.20965/jrm.2003.p0001.
Анотація:
This paper describes a three-dimensional parallel solution scheme for inverse dynamics of link mechanisms, which has already been proposed for the two-dimensional case and applied in several in-plane motions. In this theory, the entire system is subdivided into finite elements and evaluated as a continuum. A single-link structure of a pin joint and a rigid bar is expressed using the Shifted Integration (SI) technique, which is conventionally used in finite element analyses of framed structures. This scheme calculates nodal forces by evaluating equations of motion in a matrix form, and thus information from the entire system can be handled in parallel, which is a very useful characteristic when applied in closed-loop or continuously transforming mechanisms. The obtained nodal forces are then converted into the joint torque in the system. Simple numerical tests on two-dimensional and threedimensional open-loop link mechanisms are carried out for comparison with other schemes. The proposed scheme is implemented in a control system to evaluate the performance in actual control with dynamics compensation, and some control experiments are carried out on an open-loop link mechanism. The results reveal the possibility of using the proposed solution scheme in feed-forward control, independently to the system configuration of link mechanisms.
23
Kumar, Sushil, and Lionel Fourment. "Remapping Method for Transferring Data between Two Meshes Using a Modified Iterative SPR Approach for Parallel Resolution." Key Engineering Materials 504-506 (February 2012): 455–60. http://dx.doi.org/10.4028/www.scientific.net/kem.504-506.455.
Анотація:
In metal forming simulations, the transfer of data from one mesh to another can be very often required such as, in ALE formulation at each time step or in Lagrangian formulation at each remeshing step. Its accuracy is one of the main concerns for researchers, since the accumulation of generated diffusion can lead to larger numerical error and create convergence problems. Since 1992, the Super convergent Patch Recovery method (SPR) introduced by Zienkiewicz & Zhu [1], was a major breakthrough for the methods to estimate errors in FE solution. Later, it has also been used to recover nodal fields from integration points, in order to transfer data between two meshes [10]. The original method raises some difficulties to treat the domain boundaries. They have not quite properly been handled, in particular in the frame of parallel implementation, despite the fact that, surface phenomena, such as contact and friction, play such an important role in metal forming applications. In the present paper, it is presented a modified iterative SPR method which deals with boundary points with the same order of accuracy as the interior points. It does not require increasing the patch size and it is easier to implement in parallel environment. Also, when interpolating the field on new mesh, a new and consistent technique (P0+ transport) of enriched field has been used. It involves building a P1+ field by mixing the recovered SPR nodal field with the known field at integration points. Results are presented in form of convergence rate and L2 error norm, for several analytical functions for a SPR based transfer operator against a simple volumetric based transfer operator, before being applied to an actual metal forming problem. All computations presented here have been done by using four processors in parallel environment.
24
Hidayat, Mas Irfan Purbawanto, Bambang Ariwahjoedi, and Setyamartana Parman. "A new meshless local B-spline basis functions-FD method for two-dimensional heat conduction problems." International Journal of Numerical Methods for Heat & Fluid Flow 25, no. 2 (March 2, 2015): 225–51. http://dx.doi.org/10.1108/hff-05-2013-0169.
Анотація:
Purpose – The purpose of this paper is to present a new approach of meshless local B-spline based finite difference (FD) method for solving two dimensional transient heat conduction problems. Design/methodology/approach – In the present method, any governing equations are discretized by B-spline approximation which is implemented in the spirit of FD technique using a local B-spline collocation scheme. The key aspect of the method is that any derivative is stated as neighbouring nodal values based on B-spline interpolants. The set of neighbouring nodes are allowed to be randomly distributed thus enhanced flexibility in the numerical simulation can be obtained. The method requires no mesh connectivity at all for either field variable approximation or integration. Time integration is performed by using the Crank-Nicolson implicit time stepping technique. Findings – Several heat conduction problems in complex domains which represent for extended surfaces in industrial applications are examined to demonstrate the effectiveness of the present approach. Comparison of the obtained results with solutions from other numerical method available in literature is given. Excellent agreement with reference numerical method has been found. Research limitations/implications – The method is presented for 2D problems. Nevertheless, it would be also applicable for 3D problems. Practical implications – A transient two dimensional heat conduction in complex domains which represent for extended surfaces in industrial applications is presented. Originality/value – The presented new meshless local method is simple and accurate, while it is also suitable for analysis in domains of arbitrary geometries.
25
Mendonça, Flávio dos Ramos de Sousa, Wilber Humberto Vélez Gómez, and Artur Antônio de Almeida Portela. "A local meshless analysis of dynamics problems / Uma análise local desordenada dos problemas dinâmicos." Brazilian Journal of Development 7, no. 10 (October 13, 2021): 96793–812. http://dx.doi.org/10.34117/bjdv7n10-134.
Анотація:
This paper is concerned with new formulations of local meshfree numerical method, for the solution of dynamic problems in linear elasticity, Integrated Local Mesh Free (ILMF) method. The key attribute of local numerical methods is the use of a modeling paradigm based on a node-by-node calculation, to generate the rows of the global system of equations of the body discretization. In the local domain, assigned to each node of a discretization, the work theorem is kinematically formulated, leading thus to an equation of mechanical equilibrium of the local node, that is used by local meshfree method as the starting point of the formulation. The main feature of this paper is the use of a linearly integrated local form of the work theorem. The linear reduced integration plays a key role in the behavior of local numerical methods, since it implies a reduction of the nodal stiffness which, in turn, leads to an increase of the solution accuracy. As a consequence, the derived meshfree and finite element numerical methods become fast and accurate, which is a feature of paramount importance, as far as computational efficiency of numerical methods is concerned. The cantilever beam was analyzed with this technique, in order to assess the accuracy and efficiency of the new local numerical method for dynamic problems with regular and irregular nodal configuration. The results obtained in this work are in perfect agreement with Mesh-Free Local Petrov-Galerkin (MLPG) and the Finite Element Method (FEM) solutions.
26
Boscheri, Walter, and Raphaël Loubère. "High Order Accurate Direct Arbitrary-Lagrangian-Eulerian ADER-MOOD Finite Volume Schemes for Non-Conservative Hyperbolic Systems with Stiff Source Terms." Communications in Computational Physics 21, no. 1 (December 5, 2016): 271–312. http://dx.doi.org/10.4208/cicp.oa-2015-0024.
Анотація:
AbstractIn this paper we present a 2D/3D high order accurate finite volume scheme in the context of direct Arbitrary-Lagrangian-Eulerian algorithms for general hyperbolic systems of partial differential equations with non-conservative products and stiff source terms. This scheme is constructed with a single stencil polynomial reconstruction operator, a one-step space-time ADER integration which is suitably designed for dealing even with stiff sources, a nodal solver with relaxation to determine the mesh motion, a path-conservative integration technique for the treatment of non-conservative products and ana posterioristabilization procedure derived from the so-called Multidimensional Optimal Order Detection (MOOD) paradigm. In this work we consider the seven equation Baer-Nunziato model of compressible multi-phase flows as a representative model involving non-conservative products as well as relaxation source terms which are allowed to become stiff. The new scheme is validated against a set of test cases on 2D/3D unstructured moving meshes on parallel machines and the high order of accuracy achieved by the method is demonstrated by performing a numerical convergence study. Classical Riemann problems and explosion problems with exact solutions are simulated in 2D and 3D. The overall numerical code is also profiled to provide an estimate of the computational cost required by each component of the whole algorithm.
27
Phuc, Ho Le Huy, Le Van Canh, and Phan Duc Hung. "A computational homogenization analysis of materials using the stabilized mesh-free method based on the radial basis functions." Journal of Science and Technology in Civil Engineering (STCE) - NUCE 14, no. 1 (January 22, 2020): 65–76. http://dx.doi.org/10.31814/stce.nuce2020-14(1)-06.
Анотація:
This study presents a novel application of mesh-free method using the smoothed-radial basis functions for the computational homogenization analysis of materials. The displacement field corresponding to the scattered nodes within the representative volume element (RVE) is split into two parts including mean term and fluctuation term, and then the fluctuation one is approximated using the integrated radial basis function (iRBF) method. Due to the use of the stabilized conforming nodal integration (SCNI) technique, the strain rate is smoothed at discreted nodes; therefore, all constrains in resulting problems are enforced at nodes directly. Taking advantage of the shape function satisfies Kronecker-delta property, the periodic boundary conditions well-known as the most appropriate procedure for RVE are similarly imposed as in the finite element method. Several numerical examples are investigated to observe the computational aspect of iRBF procedure. The good agreement of the results in comparison with those reported in other studies demonstrates the accuracy and reliability of proposed approach.
Keywords:
homogenization analysis; mesh-free method; radial point interpolation method; SCNI scheme.
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Chen, Cheng, Kai Yuan, Winnie Chiu-wing Chu, and Raymond Kai-yu Tong. "The Effects of 10 Hz and 20 Hz tACS in Network Integration and Segregation in Chronic Stroke: A Graph Theoretical fMRI Study." Brain Sciences 11, no. 3 (March 16, 2021): 377. http://dx.doi.org/10.3390/brainsci11030377.
Анотація:
Transcranial alternating current stimulation (tACS) has emerged as a promising technique to non-invasively modulate the endogenous oscillations in the human brain. Despite its clinical potential to be applied in routine rehabilitation therapies, the underlying modulation mechanism has not been thoroughly understood, especially for patients with neurological disorders, including stroke. In this study, we aimed to investigate the frequency-specific stimulation effect of tACS in chronic stroke. Thirteen chronic stroke patients underwent tACS intervention, while resting-state functional magnetic resonance imaging (fMRI) data were collected under various frequencies (sham, 10 Hz and 20 Hz). The graph theoretical analysis indicated that 20 Hz tACS might facilitate local segregation in motor-related regions and global integration at the whole-brain level. However, 10 Hz was only observed to increase the segregation from whole-brain level. Additionally, it is also observed that, for the network in motor-related regions, the nodal clustering characteristic was decreased after 10 Hz tACS, but increased after 20 Hz tACS. Taken together, our results suggested that tACS in various frequencies might induce heterogeneous modulation effects in lesioned brains. Specifically, 20 Hz tACS might induce more modulation effects, especially in motor-related regions, and they have the potential to be applied in rehabilitation therapies to facilitate neuromodulation. Our findings might shed light on the mechanism of neural responses to tACS and facilitate effectively designing stimulation protocols with tACS in stroke in the future.
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Choi, S. J., F. X. Giraldo, J. Kim, and S. Shin. "Verification of a non-hydrostatic dynamical core using the horizontal spectral element method and vertical finite difference method: 2-D aspects." Geoscientific Model Development 7, no. 6 (November 19, 2014): 2717–31. http://dx.doi.org/10.5194/gmd-7-2717-2014.
Анотація:
Abstract. The non-hydrostatic (NH) compressible Euler equations for dry atmosphere were solved in a simplified two-dimensional (2-D) slice framework employing a spectral element method (SEM) for the horizontal discretization and a finite difference method (FDM) for the vertical discretization. By using horizontal SEM, which decomposes the physical domain into smaller pieces with a small communication stencil, a high level of scalability can be achieved. By using vertical FDM, an easy method for coupling the dynamics and existing physics packages can be provided. The SEM uses high-order nodal basis functions associated with Lagrange polynomials based on Gauss–Lobatto–Legendre (GLL) quadrature points. The FDM employs a third-order upwind-biased scheme for the vertical flux terms and a centered finite difference scheme for the vertical derivative and integral terms. For temporal integration, a time-split, third-order Runge–Kutta (RK3) integration technique was applied. The Euler equations that were used here are in flux form based on the hydrostatic pressure vertical coordinate. The equations are the same as those used in the Weather Research and Forecasting (WRF) model, but a hybrid sigma–pressure vertical coordinate was implemented in this model. We validated the model by conducting the widely used standard tests: linear hydrostatic mountain wave, tracer advection, and gravity wave over the Schär-type mountain, as well as density current, inertia–gravity wave, and rising thermal bubble. The results from these tests demonstrated that the model using the horizontal SEM and the vertical FDM is accurate and robust provided sufficient diffusion is applied. The results with various horizontal resolutions also showed convergence of second-order accuracy due to the accuracy of the time integration scheme and that of the vertical direction, although high-order basis functions were used in the horizontal. By using the 2-D slice model, we effectively showed that the combined spatial discretization method of the spectral element and finite difference methods in the horizontal and vertical directions, respectively, offers a viable method for development of an NH dynamical core.
30
Pi, Jun, and Xi Peng Xu. "Design of Integration Tool-Holder System for Ultrasonic Vibration Machining Using Contactless Inductive Power Transfer." Advanced Materials Research 69-70 (May 2009): 520–24. http://dx.doi.org/10.4028/www.scientific.net/amr.69-70.520.
Анотація:
Contactless inductive power transfer system with conventional inductive technology was studied and a design method was presented after applying it to ultrasonic vibration machining systems. The compensation techniques are used for piezoelectricity transducer. Nodal plane support of transducer is researched and models of different structures for nodal plane support are got. Influence of rotary precision for different support due to centrifugal force and displacement vibration of nodal plane support to toolholder are analyzed. The system integrated with ultrasonic-vibration toolholder based on contactless inductive power transfer is designed. Power transfer and dynamic tests show that the design procedures and result based on theoretical analysis are comparative.
31
Thai, Chien H., and H. Nguyen-Xuan. "A Moving Kriging Interpolation Meshfree Method Based on Naturally Stabilized Nodal Integration Scheme for Plate Analysis." International Journal of Computational Methods 16, no. 04 (May 13, 2019): 1850100. http://dx.doi.org/10.1142/s0219876218501001.
Анотація:
A moving Kriging interpolation (MKI) meshfree method based on naturally stabilized nodal integration (NSNI) scheme is presented to study static, free vibration and buckling behaviors of isotropic Reissner–Mindlin plates. Gradient strains are directly computed at nodes similar to the direct nodal integration (DNI). Outstanding features of the current approach are to alleviate instability solutions in the DNI and to decrease computational cost significantly when compared with the traditional high-order Gauss quadrature scheme. The NSNI is a naturally implicit gradient expansion and does not employ a divergence theorem for strain fields as addressed in the stabilized conforming nodal integration method. The present formulation is derived from the Galerkin weak form and avoids a naturally shear-locking phenomenon without using any other techniques. Thanks to satisfied Kronecker delta function property of MKI shape function, essential boundary conditions (BCs) are easily and directly enforced similar to the finite element method. A variety of numerical examples with various geometries, stiffness ratios and BCs are studied to verify the effectiveness of the present approach.
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Gianto, Rudy, and Purwoharjono Purwoharjono. "A new method to incorporate three-phase power transformer model into distribution system load flow analysis." International Journal of Applied Power Engineering (IJAPE) 10, no. 3 (September 1, 2021): 262. http://dx.doi.org/10.11591/ijape.v10.i3.pp262-270.
Анотація:
This paper proposes a new and simple method to incorporate three-phase power transformer model into distribution system load flow (DSLF) analysis. The objective of the present work is to find a robust and efficient technique for modeling and integrating power transformer in the DSLF analysis. The proposed transformer model is derived based on nodal admittance matrix and formulated by using the symmetrical component theory. Load flow formulation in terms of branch currents and nodal voltages is also proposed in this paper to enable integrating the model into the DSLF analysis. Singularity that makes the calculations in forward/backward sweep (FBS) algorithm is difficult to be carried out. It can be avoided in the method. The proposed model is verified by using the standard IEEE test system.
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Woo, Kwang Sung, Won Seok Jang, Yoo Mi Kwon, and Jun Hyung Jo. "Nodal Collocation for the P-Convergent Scheme in Boundary Element Technique." Applied Mechanics and Materials 405-408 (September 2013): 3139–42. http://dx.doi.org/10.4028/www.scientific.net/amm.405-408.3139.
Анотація:
The concept of thep-convergent boundary element modeling has been presented to analyze the potential problem with L-shaped domain. The details of thep-convergent boundary element formulation are discussed. These include the equations of nodal collocation for thep-convergent scheme, selection of higher order hierarchical shape functions, techniques for integrating the product of the kernel functions and corresponding shape functions, strategies for selecting collocation points used in approximating the unknowns associated with the higher order shape functions, and program organizations. A numerical example that demonstrates the performance of thep-convergent boundary element formulation is shown with respect to different arrangement of collocation points including both symmetric non-hierarchical pattern and non-symmetric hierarchical pattern.
34
Doyle, James A., Thomas G. Garrison, and Stephen D. Houston. "Watchful realms: integrating GIS analysis and political history in the southern Maya lowlands." Antiquity 86, no. 333 (September 2012): 792–807. http://dx.doi.org/10.1017/s0003598x0004792x.
Анотація:
Travellers naturally prefer to use the most passable routes and establish staging points on the way. Cost surface analysis predicts the easiest routes and viewshed analysis the territory visible from a staging point or destination. Applying these GIS techniques to the Buenavista Valley Corridor, our authors write a history of travel and exchange that vividly reflects the rivalry of two polities and the rise and fall of their nodal settlements.
35
van den Ende, Martijn P. A., and Jean-Paul Ampuero. "Evaluating seismic beamforming capabilities of distributed acoustic sensing arrays." Solid Earth 12, no. 4 (April 22, 2021): 915–34. http://dx.doi.org/10.5194/se-12-915-2021.
Анотація:
Abstract. The versatility and cost efficiency of fibre-optic distributed acoustic sensing (DAS) technologies facilitate geophysical monitoring in environments that were previously inaccessible for instrumentation. Moreover, the spatio-temporal data density permitted by DAS naturally appeals to seismic array processing techniques, such as beamforming for source location. However, the measurement principle of DAS is inherently different from that of conventional seismometers, providing measurements of ground strain rather than ground motion, and so the suitability of traditional seismological methods requires in-depth evaluation. In this study, we evaluate the performance of a DAS array in the task of seismic beamforming, in comparison with a co-located nodal seismometer array. We find that, even though the nodal array achieves excellent performance in localising a regional ML 4.3 earthquake, the DAS array exhibits poor waveform coherence and consequently produces inadequate beamforming results that are dominated by the signatures of shallow scattered waves. We demonstrate that this behaviour is likely inherent to the DAS measurement principle, and so new strategies need to be adopted to tailor array processing techniques to this emerging measurement technology. One strategy demonstrated here is to convert the DAS strain rates to particle velocities by spatial integration using the nodal seismometer recordings as a reference, which dramatically improves waveform coherence and beamforming performance and warrants new types of “hybrid” array design that combine dense DAS arrays with sparse seismometer arrays.
36
Codjo, Egnonnumi Lorraine, Bashir Bakhshideh Zad, Jean-François Toubeau, Bruno François, and François Vallée. "Machine Learning-Based Classification of Electrical Low Voltage Cable Degradation." Energies 14, no. 10 (May 15, 2021): 2852. http://dx.doi.org/10.3390/en14102852.
Анотація:
Low voltage distribution networks have not been traditionally designed to accommodate the large-scale integration of decentralized photovoltaic (PV) generations. The bidirectional power flows in existing networks resulting from the load demand and PV generation changes as well as the influence of ambient temperature led to voltage variations and increased the leakage current through the cable insulation. In this paper, a machine learning-based framework is implemented for the identification of cable degradation by using data from deployed smart meter (SM) measurements. Nodal voltage variations are supposed to be related to cable conditions (reduction of cable insulation thickness due to insulation wear) and to client net demand changes. Various machine learning techniques are applied for classification of nodal voltages according to the cable insulation conditions. Once trained according to the comprehensive generated datasets, the implemented techniques can classify new network operating points into a healthy or degraded cable condition with high accuracy in their predictions. The simulation results reveal that logistic regression and decision tree algorithms lead to a better prediction (with a 97.9% and 99.9% accuracy, respectively) result than the k-nearest neighbors (which reach only 76.7%). The proposed framework offers promising perspectives for the early identification of LV cable conditions by using SM measurements.
37
Oliveira, Tiago, Wilber Vélez, and Artur Portela. "Formulation of local numerical methods in linear elasticity." Multidiscipline Modeling in Materials and Structures 16, no. 5 (June 4, 2020): 853–86. http://dx.doi.org/10.1108/mmms-05-2018-0094.
Анотація:
PurposeThis paper is concerned with new formulations of local meshfree and finite element numerical methods, for the solution of two-dimensional problems in linear elasticity.Design/methodology/approachIn the local domain, assigned to each node of a discretization, the work theorem establishes an energy relationship between a statically admissible stress field and an independent kinematically admissible strain field. This relationship, derived as a weighted residual weak form, is expressed as an integral local form. Based on the independence of the stress and strain fields, this local form of the work theorem is kinematically formulated with a simple rigid-body displacement to be applied by local meshfree and finite element numerical methods. The main feature of this paper is the use of a linearly integrated local form that implements a quite simple algorithm with no further integration required.FindingsThe reduced integration, performed by this linearly integrated formulation, plays a key role in the behavior of local numerical methods, since it implies a reduction of the nodal stiffness which, in turn, leads to an increase of the solution accuracy and, which is most important, presents no instabilities, unlike nodal integration methods without stabilization. As a consequence of using such a convenient linearly integrated local form, the derived meshfree and finite element numerical methods become fast and accurate, which is a feature of paramount importance, as far as computational efficiency of numerical methods is concerned. Three benchmark problems were analyzed with these techniques, in order to assess the accuracy and efficiency of the new integrated local formulations of meshfree and finite element numerical methods. The results obtained in this work are in perfect agreement with those of the available analytical solutions and, furthermore, outperform the computational efficiency of other methods. Thus, the accuracy and efficiency of the local numerical methods presented in this paper make this a very reliable and robust formulation.Originality/valuePresentation of a new local mesh-free numerical method. The method, linearly integrated along the boundary of the local domain, implements an algorithm with no further integration required. The method is absolutely reliable, with remarkably-accurate results. The method is quite robust, with extremely-fast computations.
38
LIU, G. R., Y. LI, K. Y. DAI, M. T. LUAN, and W. XUE. "A LINEARLY CONFORMING RADIAL POINT INTERPOLATION METHOD FOR SOLID MECHANICS PROBLEMS." International Journal of Computational Methods 03, no. 04 (December 2006): 401–28. http://dx.doi.org/10.1142/s0219876206001132.
Анотація:
A linearly conforming radial point interpolation method (LC-RPIM) is presented for stress analysis of two-dimensional solids. In the LC-RPIM method, each field node is enclosed by a Voronoi polygon, and the displacement field function is approximated using RPIM shape functions of Kronecker delta function property created by simple interpolation using local nodes and radial basis functions augmented with linear polynomials to guarantee linear consistency. The system equations are then derived using the Galerkin weak form and nodal integration techniques, and the essential boundary conditions are imposed directly as in the finite element method. The LC-RPIM method is verified via various numerical examples and an extensive comparison study is conducted with the conventional RPIM, analytical approach and FEM. It is found that the presented LC-RPIM is more stable, more accurate in stress and more efficient than the conventional RPIM.
39
Zarco-Soto, Fco Javier, Pedro J. Zarco-Periñán, and Jose L. Martínez-Ramos. "Centralized Control of Distribution Networks with High Penetration of Renewable Energies." Energies 14, no. 14 (July 15, 2021): 4283. http://dx.doi.org/10.3390/en14144283.
Анотація:
Distribution networks were conceived to distribute the energy received from transmission and subtransmission to supply passive loads. This approach, however, is not valid anymore due to the presence of distributed generation, which is mainly based on renewable energies, and the increased number of plug-in electric vehicles that are connected at this voltage level for domestic use. In this paper the ongoing transition that distribution networks face is addressed. Whereas distributed renewable energy sources increase nodal voltages, electric vehicles result in demand surges higher than the load predictions considered when planning these networks, leading to congestion in distribution lines and transformers. Additionally, centralized control techniques are analyzed to reduce the impact of distributed generation and electric vehicles and increase their effective integration. A classification of the different methodologies applied to the problems of voltage control and congestion management is presented.
40
Sundararaman, KA, KP Padmanaban, M. Sabareeswaran, and S. Guharaja. "An integrated finite element method, response surface methodology, and evolutionary techniques for modeling and optimization of machining fixture layout for 3D hollow workpiece geometry." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 231, no. 23 (August 31, 2016): 4344–59. http://dx.doi.org/10.1177/0954406216668208.
Анотація:
Machining fixtures play inevitable role in manufacturing to ensure the machining accuracy and workpiece quality. The layout of fixture elements, clamping forces, and machining forces significantly affect the workpiece elastic deformation during machining. The clamping and machining forces are necessary to immobilize and machine the workpiece, respectively. Finding the appropriate layout of fixture elements is the other possible way to reduce the workpiece deformation, which in turn improves the machining accuracy. The finite element method interfaced with evolutionary techniques is normally used for fixture layout optimization. In the finite element method, the workpiece is discretized into a number of small elements and fixture elements are placed only on the nodes. Hence, evolutionary techniques are capable of searching the optimal fixture layout from those discrete nodal points than from the entire area on the locating and clamping face. To overcome these limitations, in this research paper, response surface methodology is employed to establish a quadratic model between the position of fixture elements and maximum workpiece deformation. This enables the optimization techniques to search for the optimal solution in the continuous domain of the solution space. Then, the real-coded genetic algorithm based discrete optimization, continuous optimization based on binary-coded genetic algorithm and particle swarm optimization are employed to optimize the developed quadratic model and their performances are compared. The result clearly shows that the integration of finite element method, response surface methodology with particle swarm optimization is better than the integration with genetic algorithm to optimize the machining fixture layout and also reduces the computational complexity and time to a greater extent.
41
Kulinič, Valentinas. "COMPARISON OF COMPUTER-AIDED INTEGRATION TECHNIQUES WHEN OBTAINING INITIAL DISPLACEMENTS MATRIX FOR GEOMETRICALLY NON-LINEAR LAMINATED FINITE ELEMENT /KOMPIUTERINIŲ INTEGRAVIMO TECHNOLOGIJŲ PALYGINIMAS SUDARANT GEOMETRIŠKAI NETIESINIO SLUOKSNIUOTOJO BAIGTINIO ELEMENTO PRADINIŲ POSLINKIŲ MATRICĄ." JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 7, no. 5 (October 31, 2001): 352–58. http://dx.doi.org/10.3846/13921525.2001.10531753.
Анотація:
Geometrical non-linearity of the laminated element has not been realized so far in the widely known commercial finite element method packages such as ABAQUS, ALGOR, ANSYS, COSMOS although researches in that field are actively carried out. On the other hand, there is a lot of problems where large displacements and deformations must be dealt with to obtain a precise decision. A wide range of composite orthotopic materials is used in constructions and other fields of technology. Various numerical methods were implemented to handle laminated plates and shells, however most of them are intended for application only with particular types of the structures. The author's aim is to develop a geometrically nonlinear finite element that could be effectively used for analysis of various laminated slabs regardless of their shape, thickness of laminae, properties of materials, direction of orthotropy axes, way of loading and boundary conditions. Obtaining and handling the element's initial displacement matrix used in the iteration process is a highly complicated issue requiring significant amount of computer resources to be involved. One of the most important aims of the research is to develop an element which could be used not only in an expensive multiprocessor mainframes, but also in an usual personal computer. For the structure, a sophisticated finite element TRIPLT having 50 degrees of freedom is used. The geometrical matrix for this element is obtained involving L-coordinates' array while displacements and rotations in the middle of the element are expressed through the nodal displacements (rotations), their derivatives, and displacements (rotations) in the central point. Linear and non-linear components for the geometrical matrix are shown in Eqs 2 and 5. The behaviour of a geometrical non-linear finite elements structure is described by Eq 8. The tangent stiffness matrix consists of the conventional linear elastic stiffness matrix, initial stress matrix and initial displacements matrix which is obtained by Eq 10, using both analytical and/or numerical integrating. The analytical integrating involves expanding of the appropriate expressions into basic matrices (Eqs 11, 12) and using formula 15. The initial displacement matrix in term of constitutive matrix's elements and the basic matrices is shown in Eqs 13 and 14. Numerical integrating is conducted by two methods: those using Hammer and Gauss-Radau weight coefficients. Numerical approach is applied both to the basic matrices and factorised expressions of submatrices involving intermediate arrays and matrices (Eqs 23, 24). Two ways of obtaining the intermediate arrays and matrices are discussed. Because of high complexity of the procedures involved the computer algebra system Mathematica was used for the integrating and recording FORTRAN codes. Comparison of the effectiveness of all the procedures is presented in a table. The investigation results show that the initial displacement matrix obtained by means of numerical integration involves a small amount of arithmetic operations to be handled with a usual personal computer.
42
Zhao, Bo, Zhi-Nan Zhang, and Xu-Dong Dai. "Modeling and prediction of wear at revolute clearance joints in flexible multibody systems." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 228, no. 2 (April 18, 2013): 317–29. http://dx.doi.org/10.1177/0954406213486384.
Анотація:
This article proposes a numerical approach for the modeling and prediction of wear at revolute clearance joints in flexible multibody systems by integrating the procedures of wear prediction with multibody dynamics. In the approach, the flexible component is modeled based on the absolute nodal coordinate formulation. The contact force in the clearance joint is applied using the continuous contact force model proposed by Lankanrani and Nikravesh and the friction effect is considered using the LuGre friction model. The simulation of wear is performed by an iterative wear prediction procedure based on Archard’s wear model. The radial basis function neural network technique is employed to deal with the pin-on-disc experimental data for obtaining the wear coefficient used in the wear prediction procedure at different contact conditions. The comparison of the wear predicted at the clearance joint in the rigid and flexible planar slider-crank mechanisms demonstrates that the proposed approach can be used to model and predict wear at revolute clearance joints in flexible multibody systems, and the wear result predicted is slightly reduced after taking the flexibility of components into account.
43
Vértes, Petra E., Timothy Rittman, Kirstie J. Whitaker, Rafael Romero-Garcia, František Váša, Manfred G. Kitzbichler, Konrad Wagstyl, et al. "Gene transcription profiles associated with inter-modular hubs and connection distance in human functional magnetic resonance imaging networks." Philosophical Transactions of the Royal Society B: Biological Sciences 371, no. 1705 (October 5, 2016): 20150362. http://dx.doi.org/10.1098/rstb.2015.0362.
Анотація:
Human functional magnetic resonance imaging (fMRI) brain networks have a complex topology comprising integrative components, e.g. long-distance inter-modular edges, that are theoretically associated with higher biological cost. Here, we estimated intra-modular degree, inter-modular degree and connection distance for each of 285 cortical nodes in multi-echo fMRI data from 38 healthy adults. We used the multivariate technique of partial least squares (PLS) to reduce the dimensionality of the relationships between these three nodal network parameters and prior microarray data on regional expression of 20 737 genes. The first PLS component defined a transcriptional profile associated with high intra-modular degree and short connection distance, whereas the second PLS component was associated with high inter-modular degree and long connection distance. Nodes in superior and lateral cortex with high inter-modular degree and long connection distance had local transcriptional profiles enriched for oxidative metabolism and mitochondria, and for genes specific to supragranular layers of human cortex. In contrast, primary and secondary sensory cortical nodes in posterior cortex with high intra-modular degree and short connection distance had transcriptional profiles enriched for RNA translation and nuclear components. We conclude that, as predicted, topologically integrative hubs, mediating long-distance connections between modules, are more costly in terms of mitochondrial glucose metabolism. This article is part of the themed issue ‘Interpreting BOLD: a dialogue between cognitive and cellular neuroscience’.
44
Li, Xin, Yezhou Wang, Wenxiao Wang, Weijie Huang, Kewei Chen, Kai Xu, Junying Zhang, et al. "Age-Related Decline in the Topological Efficiency of the Brain Structural Connectome and Cognitive Aging." Cerebral Cortex 30, no. 8 (March 26, 2020): 4651–61. http://dx.doi.org/10.1093/cercor/bhaa066.
Анотація:
Abstract Brain disconnection model has been proposed as a possible neural mechanism for cognitive aging. However, the relationship between structural connectivity degeneration and cognitive decline with normal aging remains unclear. In the present study, using diffusion MRI and tractography techniques, we report graph theory-based analyses of the brain structural connectome in a cross-sectional, community-based cohort of 633 cognitively healthy elderly individuals. Comprehensive neuropsychological assessment of the elderly subjects was performed. The association between age, brain structural connectome, and cognition across elderly individuals was examined. We found that the topological efficiency, modularity, and hub integration of the brain structural connectome exhibited a significant decline with normal aging, especially in the frontal, parietal, and superior temporal regions. Importantly, network efficiency was positively correlated with attention and executive function in elderly subjects and had a significant mediation effect on the age-related decline in these cognitive functions. Moreover, nodal efficiency of the brain structural connectome showed good performance for the prediction of attention and executive function in elderly individuals. Together, our findings revealed topological alterations of the brain structural connectome with normal aging, which provides possible structural substrates underlying cognitive aging and sensitive imaging markers for the individual prediction of cognitive functions in elderly subjects.
45
Ramos, J. I. "A conservative method of lines for advection-reaction-diffusion equations." International Journal of Numerical Methods for Heat & Fluid Flow 30, no. 11 (February 21, 2020): 4735–63. http://dx.doi.org/10.1108/hff-12-2019-0885.
Анотація:
Purpose The purpose of this study is to develop a new method of lines for one-dimensional (1D) advection-reaction-diffusion (ADR) equations that is conservative and provides piecewise analytical solutions in space, compare it with other finite-difference discretizations and assess the effects of advection and reaction on both 1D and two-dimensional (2D) problems. Design/methodology/approach A conservative method of lines based on the piecewise analytical integration of the two-point boundary value problems that result from the local solution of the advection-diffusion operator subject to the continuity of the dependent variables and their fluxes at the control volume boundaries is presented. The method results in nonlinear first-order, ordinary differential equations in time for the nodal values of the dependent variables at three adjacent grid points and triangular mass and source matrices, reduces to the well-known exponentially fitted techniques for constant coefficients and equally spaced grids and provides continuous solutions in space. Findings The conservative method of lines presented here results in three-point finite difference equations for the nodal values, implicitly treats the advection and diffusion terms and is unconditionally stable if the reaction terms are implicitly treated. The method is shown to be more accurate than other three-point, exponentially fitted methods for nonlinear problems with interior and/or boundary layers and/or source/reaction terms. The effects of linear advection in 1D reacting flow problems indicates that the wave front steepens as it approaches the downstream boundary, whereas its back corresponds to a translation of the initial conditions; for nonlinear advection, the wave front exhibits steepening but the wave back shows a linear dependence on space. For a system of two nonlinearly coupled, 2D ADR equations, it is shown that a counter-clockwise rotating vortical field stretches the spiral whose tip drifts about the center of the domain, whereas a clock-wise rotating one compresses the wave and thickens its arms. Originality/value A new, conservative method of lines that implicitly treats the advection and diffusion terms and provides piecewise-exponential solutions in space is presented and applied to some 1D and 2D advection reactions.
46
Osmond, Craig. "Anti-social behaviour and its surveillant inter-assemblage." Surveillance & Society 7, no. 3/4 (July 6, 2010): 325–43. http://dx.doi.org/10.24908/ss.v7i3/4.4159.
Анотація:
This paper describes a recent initiative in NSW, Australia in the state government’s “fight against anti-social behaviour”. The Anti-Social Behaviour Pilot Project has developed a surveillance regime that exempts justice and human service public authorities from existing privacy laws so that these agencies can share risk intelligence about targeted young people for a more integrated and multi-agency intensive management of risk. A detailed account of the ensemble of statements that have shaped and made this highly politicised risk governance possible is outlined. The initiative seeks to establish a more flexible mode of surveillance capable of intervening into cases of persistent risks linked to the possibility of criminal offending and the risks of persistent offending that have both become linked to public safety. Two analytical frames are used to make sense of the project. Firstly, its nodal technique for integrating case management risk across governmental assemblages (police, health etc) is analysed as an exemplar of a post-panoptical surveillant inter-assemblage designed for the networked control of young people. Secondly, Agamben’s (1988, 2005) account of the state of exception is used to demonstrate how the project’s extra-legal administrative procedures for managing risks linked to “the public interest” establish a spatial arrangement for the control of young people based on decisions of exclusion that are paradoxically located inside and outside the law.
47
Savsani, Vimal J., Ghanshyam G. Tejani, Vivek K. Patel, and Poonam Savsani. "Modified meta-heuristics using random mutation for truss topology optimization with static and dynamic constraints." Journal of Computational Design and Engineering 4, no. 2 (November 2, 2016): 106–30. http://dx.doi.org/10.1016/j.jcde.2016.10.002.
Анотація:
AbstractIn this paper, simultaneous size and topology optimization of planar and space trusses subjected to static and dynamic constraints are investigated. All the benchmark trusses consider discrete cross-sectional areas to consider the practical aspect of manufacturing. Moreover, Trusses are considered with multiple loading conditions and subjected to constraints for natural frequencies, element stresses, nodal displacements, Euler buckling criteria, and kinematic stability conditions. Truss topology optimization (TTO) can be accomplished by the removal of superfluous elements and nodes from the highly hyper static truss also known as the ground structure and results in the saving of the mass of the truss. In this method, the difficulties arise due to the singular solution and unnecessary analysis; therefore, FEA model is reformed to resolve these difficulties.The static and dynamic responses to the TTO problems are challenging due to its search space, which is implicit, non-convex, non-linear, and often leading to divergence. Modified meta-heuristics are effective optimization methods to handle such problems in actual fact. In this paper, modified versions of Teaching–Learning-Based Optimization (TLBO), Heat Transfer Search (HTS), Water Wave Optimization (WWO), and Passing Vehicle Search (PVS) are proposed by integrating the random mutation-based search technique with them. This paper compares the performance of four modified and four basic meta-heuristics to solve discrete TTO problems.Highlights Modifications in four different recently developed meta-heuristics. Use of random mutation based strategy. Implementation on challenging/benchmark truss topology optimization problems. Modifications effective over basic algorithms.
48
Pozdnyakov, V. M. "Psychological jurisprudence as an interdisciplinary science and the area of psychological practice." Psychology and Law 7, no. 1 (2017): 206–19. http://dx.doi.org/10.17759/psylaw.2017070117.
Анотація:
The article convincingly demonstrates that Russia is increasingly began to publish monographs lawyers on key legal and psychological phenomena, and in dissertations in the formulation of the provisions on the protection of delatsya criticism of "Westernization" of the state legislation and upheld psychologicaland position. At the same time, critically, it is noted that in the field of legal ideology and policies, and in making innovations in the law still, as in Soviet period, dominated by legal dogma, and psychological realities are taken into account in fragments. The reason for this state of Affairs is that still within the framework of University training and further education of local lawyers, in contrast to international practice, insufficient attention is paid to the development of psychological culture, but in the end no full-fledged dialogue between lawyers and psychologists. Taking into account possibilities of integrative methodology justified the subject of psychological law as an interdisciplinary science and the field of psychological practice focused on the identification of regularities and mechanisms of development of legal awareness and legal existence of various actors in the legal activity aimed at the development of psychologically informed interventions for the improvement of legal ideology and politics, systems of law-making, law enforcement and crime prevention, psycho-technical methods and techniques in activities of law enforcement officials. For constructive development of psychological jurisprudence identified the key areas of research and nodal practicerelevant problems.
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von Specht, Sebastian, and Fabrice Cotton. "A Link between Machine Learning and Optimization in Ground-Motion Model Development: Weighted Mixed-Effects Regression with Data-Driven Probabilistic Earthquake Classification." Bulletin of the Seismological Society of America 110, no. 6 (July 14, 2020): 2777–800. http://dx.doi.org/10.1785/0120190133.
Анотація:
ABSTRACT The steady increase of ground-motion data not only allows new possibilities but also comes with new challenges in the development of ground-motion models (GMMs). Data classification techniques (e.g., cluster analysis) do not only produce deterministic classifications but also probabilistic classifications (e.g., probabilities for each datum to belong to a given class or cluster). One challenge is the integration of such continuous classification in regressions for GMM development such as the widely used mixed-effects model. We address this issue by introducing an extension of the mixed-effects model to incorporate data weighting. The parameter estimation of the mixed-effects model, that is, fixed-effects coefficients of the GMMs and the random-effects variances, are based on the weighted likelihood function, which also provides analytic uncertainty estimates. The data weighting permits for earthquake classification beyond the classical, expert-driven, binary classification based, for example, on event depth, distance to trench, style of faulting, and fault dip angle. We apply Angular Classification with Expectation–maximization, an algorithm to identify clusters of nodal planes from focal mechanisms to differentiate between, for example, interface- and intraslab-type events. Classification is continuous, that is, no event belongs completely to one class, which is taken into account in the ground-motion modeling. The theoretical framework described in this article allows for a fully automatic calibration of ground-motion models using large databases with automated classification and processing of earthquake and ground-motion data. As an example, we developed a GMM on the basis of the GMM by Montalva et al. (2017) with data from the strong-motion flat file of Bastías and Montalva (2016) with ∼2400 records from 319 events in the Chilean subduction zone. Our GMM with the data-driven classification is comparable to the expert-classification-based model. Furthermore, the model shows temporal variations of the between-event residuals before and after large earthquakes in the region.
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Hathuc, Vivian, and Friederike Kreisel. "Genetic Landscape of Peripheral T-Cell Lymphoma." Life 12, no. 3 (March 11, 2022): 410. http://dx.doi.org/10.3390/life12030410.
Анотація:
Peripheral T-Cell lymphoma (PTCL) comprises a heterogenous group of uncommon lymphomas derived from mature, post-thymic or “peripheral” T- and natural killer cells. The World Health Organization (WHO) emphasizes a multiparameter approach in the diagnosis and subclassification of these neoplasms, integrating clinical, morphologic, immunophenotypic, and genetic features into the final diagnosis. Clinical presentation is particularly important due to histologic, immunophenotypic and genetic variations within established subtypes, and no convenient immunophenotypic marker of monoclonality exists. In recent years, widespread use of gene expression profiling and next-generation sequencing (NGS) techniques have contributed to an improved understanding of the pathobiology in PTCLs, and these have been incorporated into the 2016 revised WHO classification of mature T- and NK-cell neoplasms which now encompasses nearly 30 distinct entities. This review discusses the genetic landscape of PTCL and its role in subclassification, prognosis, and potential targeted therapy. In addition to discussing T-Cell lymphoma subtypes with relatively well-defined or relevant genetic aberrancies, special attention is given to genetic advances in T-Cell lymphomas of T follicular helper cell (TFH) origin, highlighting genetic overlaps between angioimmunoblastic T-Cell lymphoma (AITL), follicular T-Cell lymphoma, and nodal peripheral T-Cell lymphoma with a TFH phenotype. Furthermore, genetic drivers will be discussed for ALK-negative anaplastic large cell lymphomas and their role in differentiating these from CD30+ peripheral T-Cell lymphoma, not otherwise specified (NOS) and primary cutaneous anaplastic large cell lymphoma. Lastly, a closer look is given to genetic pathways in peripheral T-Cell lymphoma, NOS, which may guide in teasing out more specific entities in a group of T-Cell lymphomas that represents the most common subcategory and is sometimes referred to as a “wastebasket” category.