Large area chemical vapour deposition grown transition metal dichalcogenide monolayers automatically characterized through photoluminescence imaging

Chemical vapour deposition (CVD) growth is capable of producing multiple single-crystal islands of atomically thin transition metal dichalcogenides (TMDs) over large areas. Subsequent merging of perfectly epitaxial domains can lead to single-crystal monolayer sheets, a step towards scalable production of high quality TMDs. For CVD growth to be effectively harnessed for such production it is necessary to be able to rapidly assess the quality of material across entire large area substrates. To date, characterisation has been limited to sub-0.1-mm2 areas, where the properties measured are not necessarily representative of an entire sample. Here, we apply photoluminescence (PL) imaging and computer vision techniques to create an automated analysis for large area samples of monolayer TMDs, measuring the properties of island size, density of islands, relative PL intensity and homogeneity, and orientation of triangular domains. The analysis is applied to ×20 magnification optical microscopy images that completely map samples of WSe2 on hBN, 5.0 mm × 5.0 mm in size, and MoSe2–WS2 on SiO2/Si, 11.2 mm × 5.8 mm in size. Two prevailing orientations of epitaxial growth were observed in WSe2 grown on hBN and four predominant orientations were observed in MoSe2, initially grown on c-plane sapphire. The proposed analysis will greatly reduce the time needed to study freshly synthesised material over large area substrates and provide feedback to optimise growth conditions, advancing techniques to produce high quality TMD monolayer sheets for commercial applications

differential quadrature method (DQM)

In this work, accurate solutions to linear and nonlinear diffusion equations were introduced. A polynomial-based differential quadrature scheme in space and a strong stability preserving Runge-Kutta scheme in time have been combined for solving these equations. This scheme needs less storage space, as opposed to conventional numerical methods, and causes less accumulation of numerical errors. The results computed by this way have been compared with the exact solutions to show the accuracy of the method. The approximate solutions to the nonlinear equation have been computed without transforming the equation and without using the linearization. The present results are seen to be a very reliable alternative method to the existing techniques for the problems. In order to obtain physical models much closer to the nature, this procedure has a potential to be used to other nonlinear partial differential equations. Copyright (C) 2009 John Wiley & Sons, Ltd

using a differential evolution algorithm

In this study, an accurate model was developed for solving problems of groundwater-pollution-source identification. In the developed model, the numerical simulations of flow and pollutant transport in groundwater were carried out using MODFLOW and MT3DMS software. The optimization processes were carried out using a differential evolution algorithm. The performance of the developed model was tested on two hypothetical aquifer models using real and noisy observation data. In the first model, the release histories of the pollution sources were determined assuming that the numbers, locations and active stress periods of the sources are known. In the second model, the release histories of the pollution sources were determined assuming that there is no information on the sources. The results obtained by the developed model were found to be better than those reported in literature

sine-Gordon equation

This paper explores the utility of a sixth-order compact finite difference (CFD6) scheme for the solution of the sine-Gordon equation. The CFD6 scheme in space and a third-order strong stability preserving Runge-Kutta scheme in time have been combined for solving the equation. This scheme needs less storage space, as opposed to the conventional numerical methods, and causes to less accumulation of numerical errors. The scheme is implemented to solve three test problems having exact solutions. Comparisons of the computed results with exact solutions showed that the method is capable of achieving high accuracy with minimal computational effort. The present results are also seen to be more accurate than some available results given in the literature. The scheme is seen to be a very reliable alternative technique to existing ones. Copyright (C) 2009 John Wiley & Sons, Ltd

Burgers-Fisher Equation

In this article, numerical Solutions of the generalized Burgers-Fisher equation are obtained using compact finite difference method with minimal compuatational effort. To verify this, a combination of a sixth-order compact finite difference scheme in space and a low-storage third-order total variation diminishing Runge-Kutta scheme in time have been used. The computed results with the use Of this technique have been compared with the exact Solution to show the accuracy of it. The approximate solutions to the equation have been computed without transforming the equation and without using linearization. Comparisons indicate that there is a very good agreement between the numerical solutions and the exact solutions in terms of accuracy. The present method is seen to be a very good alternative to some existing techniques for realistic problems. (C) 2009 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 26: 125-134, 201

Weekly cases of selected notifiable diseases ( 65 1,000 cases reported during the preceding year), and selected low frequency diseases, United States and U.S. territories, week ending December 15, 2018 (WEEK 50). TABLE 2o, Salmonellosis (excluding typhoid fever and paratyphoid fever); Shiga toxin-producing Escherichia coli; Shigellosis

2018-50-table2O-H.pdfSalmonellosis (excluding typhoid fever and paratyphoid fever)-- Shiga toxin-producing Escherichia coli --Shigellosis.2018739

2016 child and adolescent immunization schedule

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HIGH-ORDER FINITE DIFFERENCE SCHEMES FOR SOLVING THE ADVECTION-DIFFUSION

Up to tenth-order finite difference schemes are proposed in this paper to solve one-dimensional advection-diffusion equation. The schemes based on high-order differences are presented using Taylor series expansion. To obtain the solutions, up to tenth-order finite difference schemes in space and a fourth-order Runge-Kutta scheme in time have been combined. The methods are implemented to solve two problems having exact solutions. Numerical experiments have been conducted to demonstrate the efficiency and high-order accuracy of the current methods. The techniques are seen to be very accurate in solving the advection-diffusion equation for Pe <= 5. The produced results are also seen to be more accurate than some available results given in the literature

Burgers-Fisher equation

Up to tenth-order finite difference (FD) schemes are proposed in this paper to solve the generalized Burgers-Fisher equation. The schemes based on high-order differences are presented using Taylor series expansion. To obtain the solutions, up to tenth-order FD schemes in space and fourth-order Runge-Kutta scheme in time have been combined. Numerical experiments have been conducted to demonstrate the efficiency and high-order accuracy of the present methods. The produced results are also seen to be more accurate than some available results given in the literature. Comparisons showed that there is very good agreement between the numerical solutions and the exact solutions in terms of accuracy. The present methods are seen to be very good alternatives to some existing techniques for such realistic problems. Copyright (C) 2009 John Wiley & Sons, Ltd