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| 1 | Surface bioactivation of PEEK by neutral atom beam technology显示文摘Polyetheretherketone(PEEK)is an alternative to metallic implants and a material of choice in many applications,including orthopedic,spinal,trauma,and dental.While titanium(Ti)and Ti-alloys are widely used in many intraosseous implants due to its biocompatibility and ability to osseointegrate,negatives include stiffness which contributes to shear stress,radio-opacity,and Ti-sensitivity.Many surgeons prefer to use PEEK due to its biocompatibility,similar elasticity to bone,and radiolucency,however,due to its inert properties,it fails to fully integrate with bone.Accelerated Neutral Atom Beam(ANAB)technology has been successfully employed to demonstrate enhanced bioactivity of PEEK both in vitro and in vivo.In this study,we further characterize surfaces of PEEK modified by ANAB as well as elucidate attachment and genetic effects of dental pulp stem cells(DPSC)exposed to these surfaces.ANAB modification resulted in decreased contact angle at 72.9±4.5°as compared to 92.4±8.5°for control(p<0.01)and a decreased average surface roughness,however with a nano-textured surface profile.ANAB treatment also increased the ability of DPSC attachment and proliferation with considerable genetic differences showing earlier progression towards osteogenic differentiation.This surface modification is achieved without adding a coating or changing the chemical composition of the PEEK material.Taken together,we show that ANAB processing of PEEK surface enhances the bioactivity of implantable medical devices without an additive or a coating. | Joseph Khoury Irina Selezneva Sergei Pestov Vadim Tarassov Artem Ermakov Andrey Mikheev Mikhail Lazov Sean R.Kirkpatrick Dmitry Shashkov Alexandre Smolkov | 2019 | Bioactive Materials2019，4，1： | 2 |
| 2 | Enforcing the Discrete Maximum Principle for Linear Finite Element Solutions of Second-Order Elliptic Problems显示文摘The maximum principle is a basic qualitative property of the solution of second-order elliptic boundary value problems.The preservation of the qualitative characteristics,such as the maximum principle,in discrete model is one of the key requirements.It is well known that standard linear finite element solution does not satisfy maximum principle on general triangular meshes in 2D.In this paper we consider how to enforce discrete maximum principle for linear finite element solutions for the linear second-order self-adjoint elliptic equation.First approach is based on repair technique,which is a posteriori correction of the discrete solution.Second method is based on constrained optimization.Numerical tests that include anisotropic cases demonstrate how our method works for problems for which the standard finite element methods produce numerical solutions that violate the discrete maximum principle. | Richard Liska Mikhail Shashkov | 2008 | Communications in Computational Physics2008，3，4： | 2 |
| 3 | Polygonal surface mesh optimization显示文摘 | Rao V. Garimella Mikhail J. Shashkov | 2004 | Engineering with Computers2004，，3： | 1 |
| 4 | Solving diffusion equation with rough coefficients in rough grids显示文摘 | Shashkov Mikhail J Steinberg Stanly | 1996 | J Comput Phys1996，129，： | 1 |
| 5 | Untangling of 2D meshes in ALE simulations显示文摘 | Pavel Vachal Rao V Garimella Mikhail J Shashkov | 2004 | J Comput Phys2004，196，： | 1 |
| 6 | The Error-Minimization-Based Strategy for Moving Mesh Methods显示文摘The typical elements in a numerical simulation of fluid flow using moving meshes are a time integration scheme,a rezone method in which a new mesh is defined,and a remapping(conservative interpolation)in which a solution is transferred to the new mesh.The objective of the rezone method is to move the computational mesh to improve the robustness,accuracy and eventually efficiency of the simulation.In this paper,we consider the onedimensional viscous Burgers’equation and describe a new rezone strategy which minimizes the L2 norm of error and maintains mesh smoothness.The efficiency of the proposed method is demonstrated with numerical examples. | Konstantin Lipnikov Mikhail Shashkov | 2006 | Communications in Computational Physics2006，1，1： | 0 |
| 7 | THE EARLY INFLUENCE OF PETER LAX ON COMPUTATIONAL HYDRODYNAMICS AND AN APPLICATION OF LAX-FRIEDRICHS AND LAX-WENDROFF ON TRIANGULAR GRIDS IN LAGRANGIAN COORDINATES显示文摘We give a brief discussion of some of the contributions of Peter Lax to Computational Fluid Dynamics. These include the Lax-Friedrichs and Lax-Wendroff numerical schemes. We also mention his collaboration in the 1983 HLL Riemann solver. We develop two-dimensional Lax-Friedrichs and Lax-Wendroff schemes for the Lagrangian form of the Euler equations on triangular grids. We apply a composite scheme that uses a Lax-Friedrichs time step as a dissipative filter after several Lax-Wendroff time steps. Numerical results for Noh's infinite strength shock problem, the Sedov blast wave problem, and the Saltzman piston problem are presented. | Richard Liska Mikhail Shashkov Burton Wendroff | 2011 | Acta Mathematica Scientia2011，31，6： | 0 |
| 8 | R-Adaptive Reconnection-basedArbitrary Lagrangian EulerianMethod-R-ReALE显示文摘We present a new R-adaptive Arbitrary Lagrangian Eulerian(ALE)method,based on the reconnection-based ALE-ReALE methodology[5,41,42].The main elements in a standard ReALE method are:an explicit Lagrangian phase on an arbitrary polygonal(in 2D)mesh,followed by a rezoning phase in which a new grid is defined,and a remapping phase in which the Lagrangian solution is transferred onto the new grid.The rezoned mesh is smoothed by using one or several steps toward centroidal Voronoi tessellation,but it is not adapted to the solution in any way.We present a new R-adaptive ReALE method(R-ReALE,where R stands for Relocation).The new method is based on the following design principles.First,a monitor function(or error indicator)based on Hessian of some flow parameter(s),is utilized.Second,the new algorithm uses the equidistribution principle with respect to the monitor function as criterion for defining an adaptive mesh.Third,centroidal Voronoi tessellation is used for the construction of the adaptive mesh.Fourth,we modify the raw monitor function(scale it to avoid extremely small and large cells and smooth it to create a smooth mesh),in order to utilize theoretical results related to centroidal Voronoi tessellation.In the R-ReALEmethod,the number of mesh cells is chosen at the beginning of the calculation and does not changewith time,but themesh is adapted according to themodified monitor function during the rezone stage at each time step.We present all details required for implementation of the new adaptive R-ReALE method and demonstrate its performance relative to standard ReALEmethod on a series of numerical examples. | Wurigen Bo Mikhail Shashkov | 2015 | Journal of Mathematical Study2015，48，2： | 0 |
| 9 | A Multi-Material CCALE-MOF Approach in Cylindrical Geometry显示文摘In this paper we present recent developments concerning a Cell-Centered Arbitrary Lagrangian Eulerian(CCALE)strategy using the Moment Of Fluid(MOF)interface reconstruction for the numerical simulation of multi-material compressible fluid flows on unstructured grids in cylindrical geometries.Especially,our attention is focused here on the following points.First,we propose a new formulation of the scheme used during the Lagrangian phase in the particular case of axisymmetric geometries.Then,the MOF method is considered for multi-interface reconstruction in cylindrical geometry.Subsequently,a method devoted to the rezoning of polar meshes is detailed.Finally,a generalization of the hybrid remapping to cylindrical geometries is presented.These explorations are validated by mean of several test cases using unstructured grid that clearly illustrate the robustness and accuracy of the new method. | Marie Billaud Friess Jerome Breil Pierre-Henri Maire Mikhail Shashkov | 2014 | Communications in Computational Physics2014，15，2： | 0 |
| 10 | Machine learning-based method to adjust electron anomalous conductivity profile to experimentally measured operating parameters of Hall thruster显示文摘The problem of determining the electron anomalous conductivity profile in a Hall thruster,when its operating parameters are known from the experiment,is considered.To solve the problem,we propose varying the parametrically set anomalous conductivity profile until the calculated operating parameters match the experimentally measured ones in the best way.The axial 1D3V hybrid model was used to calculate the operating parameters with parametrically set conductivity.Variation of the conductivity profile was performed using Bayesian optimization with a Gaussian process(machine learning method),which can resolve all local minima,even for noisy functions.The calculated solution corresponding to the measured operating parameters of a Hall thruster in the best way proved to be unique for the studied operating modes of KM-88.The local plasma parameters were calculated and compared to the measured ones for four different operating modes.The results show the qualitative agreement.An agreement between calculated and measured local parameters can be improved with a more accurate model of plasma-wall interaction. | Andrey SHASHKOV Mikhail TYUSHEV Alexander LOVTSOV Dmitry TOMILIN Dmitrii KRAVCHENKO | 2022 | Plasma Science and Technology2022，24，6： | 0 |
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