Rapidly convergent quasi-periodic Green functions for scattering by arrays of cylinders---including Wood anomalies

This paper presents a full-spectrum Green function methodology (which is valid, in particular, at and around Wood-anomaly frequencies) for evaluation of scattering by periodic arrays of cylinders of arbitrary cross section-with application to wire gratings, particle arrays and reflectarrays and, indeed, general arrays of conducting or dielectric bounded obstacles under both TE and TM polarized illumination. The proposed method, which, for definiteness is demonstrated here for arrays of perfectly conducting particles under TE polarization, is based on use of the shifted Green-function method introduced in the recent contribution (Bruno and Delourme, Jour. Computat. Phys. pp. 262--290 (2014)). A certain infinite term arises at Wood anomalies for the cylinder-array problems considered here that is not present in the previous rough-surface case. As shown in this paper, these infinite terms can be treated via an application of ideas related to the Woodbury-Sherman-Morrison formulae. The resulting approach, which is applicable to general arrays of obstacles even at and around Wood-anomaly frequencies, exhibits fast convergence and high accuracies. For example, a few hundreds of milliseconds suffice for the proposed approach to evaluate solutions throughout the resonance region (wavelengths comparable to the period and cylinder sizes) with full single-precision accuracy

On the evaluation of quasi-periodic Green functions and wave-scattering at and around Rayleigh-Wood anomalies

This article presents full-spectrum, well-conditioned, Green-function methodologies for evaluation of scattering by general periodic structures, which remains applicable on a set of challenging singular configurations, usually called Rayleigh-Wood (RW) anomalies (at which the quasi-periodic Green function ceases to exist), where most existing quasi-periodic solvers break down. After reviewing a variety of existing fast-converging numerical procedures commonly used to compute the classical quasi-periodic Green-function, the present work explores the difficulties they present around RW-anomalies and introduces the concept of hybrid “spatial/spectral” representations. Such expressions allow both the modification of existing methods to obtain convergence at RW-anomalies as well as the application of a slight generalization of the Woodbury-Sherman-Morrison formulae together with a limiting procedure to bypass the singularities. (Although, for definiteness, the overall approach is applied to the scalar (acoustic) wave-scattering problem in the frequency domain, the approach can be extended in a straightforward manner to the harmonic Maxwell's and elasticity equations.) Ultimately, this thorough study of RW-anomalies yields fast and highly-accurate solvers, which are demonstrated with a variety of simulations of wave-scattering phenomena by arrays of particles, crossed impenetrable and penetrable diffraction gratings and other related structures. In particular, the methods developed in this article can be used to “upgrade” classical approaches, resulting in algorithms that are applicable throughout the spectrum, and it provides new methods for cases where previous approaches are either costly or fail altogether. In particular, it is suggested that the proposed shifted Green function approach may provide the only viable alternative for treatment of three-dimensional high-frequency configurations with either one or two directions of periodicity. A variety of computational examples are presented which demonstrate the flexibility of the overall approach

Penerapan Metode Aktiva Tetap Pada Pt.guntur Kabupaten Purwakata

Adanya transaksi antar negara dan prinsip-prinsip akuntansi yang berbeda antar negara mengakibatkan munculnya kebutuhan akan standar akuntansi yang berlaku secara Internasional. Oleh karena itu muncul organisasi yang bernama IASB atau International Accounting Standar Board yang mengeluarkan International Financial Reporting Standar (IFRS). Tujuan penulisan skripsi ini adalah untuk mengetahui tentang bagaimana perlakuan akuntansi terhadap aktiva tetap pada PT.Guntur Kabupaten Purwakata apakah sesuai dengan PSAK No 16 yang mengatur tentang aktiva tetap dan untuk mengetahui bagaimana perlakuan akuntansi terhadap aktiva tetap pada PT.Guntur Kabupaten Purwakata jika ditinjau dari PSAK (Konvergensi IFRS)

Laser-plasma interactions with a Fourier-Bessel Particle-in-Cell method

A new spectral particle-in-cell (PIC) method for plasma modeling is presented and discussed. In the proposed scheme, the Fourier-Bessel transform is used to translate the Maxwell equations to the quasi-cylindrical spectral domain. In this domain, the equations are solved analytically in time, and the spatial derivatives are approximated with high accuracy. In contrast to the finite-difference time domain (FDTD) methods that are commonly used in PIC, the developed method does not produce numerical dispersion, and does not involve grid staggering for the electric and magnetic fields. These features are especially valuable in modeling the wakefield acceleration of particles in plasmas. The proposed algorithm is implemented in the code PLARES-PIC, and the test simulations of laser plasma interactions are compared to the ones done with the quasi-cylindrical FDTD PIC code CALDER-CIRC.Comment: submitted to Phys. Plasma

Elektrodeposisi Lapisan Komposit Cu-al2o3 dalam Larutan Cuso4 yang Didoping dengan Partikel Nano Al2o3

ELEKTRODEPOSISI LAPISAN KOMPOSIT Cu-Al2O3 DALAM LARUTAN CuSO4 YANG DIDOPING DENGAN PARTIKEL NANO Al2O3. Lapisan komposit Cu-Al2O3 dibuat dengan menggunakan proses elektrodeposisi. Pada lapisan komposit ini, lapisan Cu berperan sebagai matriks komposit sedangkan nanopartikelAl2O3 berperan sebagai partikel penguat komposit (reinforcement). Lapisan komposit ini merupakan kelompok komposit bermatriks logam (MetalMatrix Composite). Proses elektro deposisi dilakukan pada media larutan elektrolit CuSO4, sedangkan arus listrik di suplai melalui rectifier (DC Current). Katoda yang digunakan pada proses ini adalah pelat Alumunium AA1100 dan anoda berupa grafit atau karbon. Besarnya arus yang digunakan pada proses ini adalah 0,3 A, sedangkan konsentrasi nanopartikel Al2O3 yang ditambahkan pada larutan elektrolit adalah 0,05 g/L. Proses dilakukan pada suhu kamar dan ukuran partikel nano yang digunakan adalah 50 nm. Variasi waktu proses elektrodeposisi adalah 15 menit, 30 menit dan 60 menit dan variasi konsentrasi larutan CuSO4 adalah 200 g/L, 220 g/L dan 240 g/L CuSO4 . Untuk mengetahui peranan dari nanopartikel yang ditambahkan, maka dilakukan beberapa pengujian dan pemeriksaan laboratorium seperti pengujian kekerasan, pemeriksaan strukturmikro. Pemeriksaan Scanning Electron Microscope (SEM) dan pengujian Electron Dispersive Spectroscopy (EDS). Pembuatan lapisan komposit ini bertujuan untuk mendapatkan karakteristik lapisan yang sifat mekaniknya lebih baik

Realisasi Janji Kampanye Program Kesehatan Bupati Semarang Periode 2010-2015

IONHealth program is the flagship program of the couple Mundjirin and Warnadi. Health programs are favored free treatment at health centers and classrooms III general hospitals. This study uses qualitative methods research that produces descriptive data described with words written and spoken by the people as well as observations of behavior to determine how the realization of campaign promises the couples Mundijirin and Warnadi in elections of regional heads Semarang district 2010. The results showed that the campaign promises of health programs in the form of Semarang regency regent free health programs truly realized