Investigation of the Holding Capability of the Dielectrophoretic Gate and Sorter System for Biodetection

The dielectrophoretic gate and sorter system has been widely applied for preconcentrating and sorting of bioparticles for biodetection. In such systems, the dielectrophoretic force is generated by applying an AC electric field on the three dimensional electrode systems (containing a pair of electrodes on the top and bottom of the channel). Particles are held and sorted by balancing the DEP force with the hydrodynamic drag force. The holding capability is very important for such systems because it determines the preconcentration and sorting efficiency. In this paper, we investigate the holding capability of a simple dielectrophoretic gate system. Initially, a three dimensional numerical scheme was introduced to estimate the holding capability and was further validated by comparing with experimental results. Second, we systematically investigated the effects of the phase difference between the top and bottom electrodes;the height and width of the channel, and the relative position and size of top and bottom electrodes. The results demonstrated that the maximum holding capability is reached when the phase difference between the top and bottom electrodes is around 180o. The results also show that the holding capability varied with the size and relative position of electrodes on the top and bottom, and the maximum holding capability is obtained when the top and bottom electrodes had the same size and the centers of both electrodes overlapped.

Machine-learning-based intelligent framework for discovering refractory high-entropy alloys with improved high-temperature yield strength

Refractory high-entropy alloys(RHEAs)show significant elevated-temperature yield strengths and have potential to use as high-performance materials in gas turbine engines.Exploring the vast RHEA compositional space experimentally is challenging,and a small fraction of this space has been explored to date.This work demonstrates the development of a state-of-the-art machine learning framework coupled with optimization methods to intelligently explore the vast compositional space and drive the search in a direction that improves high-temperature yield strengths.Our yield strength model is shown to have a significantly improved predictive accuracy relative to the state-of-the-art approach,and also provides inherent uncertainty quantification through the use of repeated k-fold cross-validation.Upon developing and validating a robust yield strength prediction model,the coupled framework is used to discover RHEAs with superior high temperature yield strength.We have shown that RHEA compositions can be customized to have maximum yield strength at a specific temperature.

A High Order Spectral Volume Formulation for Solving Equations Containing Higher Spatial Derivative Terms II:Improving the Third Derivative Spatial Discretization Using the LDG2 Method

In this paper,the second in a series,we improve the discretization of the higher spatial derivative terms in a spectral volume(SV)context.The motivation for the above comes from[J.Sci.Comput.,46(2),314–328],wherein the authors developed a variant of the LDG(Local Discontinuous Galerkin)flux discretization method.This variant(aptly named LDG2),not only displayed higher accuracy than the LDG approach,but also vastly reduced its unsymmetrical nature.In this paper,we adapt the LDG2 formulation for discretizing third derivative terms.A linear Fourier analysis was performed to compare the dispersion and the dissipation properties of the LDG2 and the LDG formulations.The results of the analysis showed that the LDG2 scheme(i)is stable for 2nd and 3rd orders and(ii)generates smaller dissipation and dispersion errors than the LDG formulation for all the orders.The 4th order LDG2 scheme is howevermildly unstable:as the real component of the principal eigen value briefly becomes positive.In order to circumvent the above,a weighted average of the LDG and the LDG2 fluxes was used as the final numerical flux.Even a weight of 1.5%for the LDG(i.e.,98.5%for the LDG2)was sufficient tomake the scheme stable.Thisweighted scheme is still predominantly LDG2 and hence generated smaller dissipation and dispersion errors than the LDG formulation.Numerical experiments are performed to validate the analysis.In general,the numerical results are very promising and indicate that the approach has a great potential for higher dimension Korteweg-de Vries(KdV)type problems.

A High Order Spectral Volume Formulation for Solving Equations Containing Higher Spatial Derivative Terms:Formulation and Analysis for Third Derivative Spatial Terms Using the LDG Discretization Procedure

In this paper,we develop a formulation for solving equations containing higher spatial derivative terms in a spectral volume(SV)context;more specifically the emphasis is on handling equations containing third derivative terms.This formulation is based on the LDG(Local Discontinuous Galerkin)flux discretization method,originally employed for viscous equations containing second derivatives.A linear Fourier analysis was performed to study the dispersion and the dissipation properties of the new formulation.The Fourier analysis was utilized for two purposes:firstly to eliminate all the unstable SV partitions,secondly to obtain the optimal SV partition.Numerical experiments are performed to illustrate the capability of this formulation.Since this formulation is extremely local,it can be easily parallelized and a h-p adaptation is relatively straightforward to implement.In general,the numerical results are very promising and indicate that the approach has a great potential for higher dimension Korteweg-de Vries(KdV)type problems.

Improving the High Order Spectral Volume Formulation Using a Diffusion Regulator

The concept of diffusion regulation(DR)was originally proposed by Jaisankar for traditional second order finite volume Euler solvers.This was used to decrease the inherent dissipation associated with using approximate Riemann solvers.In this paper,the above concept is extended to the high order spectral volume(SV)method.The DR formulation was used in conjunction with the Rusanov flux to handle the inviscid flux terms.Numerical experiments were conducted to compare and contrast the original and the DR formulations.These experiments demonstrated(i)retention of high order accuracy for the new formulation,(ii)higher fidelity of the DR formulation,when compared to the original scheme for all orders and(iii)straightforward extension to Navier Stokes equations,since the DR does not interfere with the discretization of the viscous fluxes.In general,the 2D numerical results are very promising and indicate that the approach has a great potential for 3D flow problems.