ROBAST: Development of a ROOT-Based Ray-Tracing Library for Cosmic-Ray Telescopes and its Applications in the Cherenkov Telescope Array

We have developed a non-sequential ray-tracing simulation library, ROOT-based simulator for ray tracing (ROBAST), which is aimed to be widely used in optical simulations of cosmic-ray (CR) and gamma-ray telescopes. The library is written in C++, and fully utilizes the geometry library of the ROOT framework. Despite the importance of optics simulations in CR experiments, no open-source software for ray-tracing simulations that can be widely used in the community has existed. To reduce the dispensable effort needed to develop multiple ray-tracing simulators by different research groups, we have successfully used ROBAST for many years to perform optics simulations for the Cherenkov Telescope Array (CTA). Among the six proposed telescope designs for CTA, ROBAST is currently used for three telescopes: a Schwarzschild-Couder (SC) medium-sized telescope, one of SC small-sized telescopes, and a large-sized telescope (LST). ROBAST is also used for the simulation and development of hexagonal light concentrators proposed for the LST focal plane. Making full use of the ROOT geometry library with additional ROBAST classes, we are able to build the complex optics geometries typically used in CR experiments and ground-based gamma-ray telescopes. We introduce ROBAST and its features developed for CR experiments, and show several successful applications for CTA.Comment: Accepted for publication in Astroparticle Physics. 11 pages, 10 figures, 4 table

ROBAST: Development of a Non-Sequential Ray-Tracing Simulation Library and its Applications in the Cherenkov Telescope Array

We have developed a non-sequential ray-tracing simulation library, ROot-BAsed Simulator for ray Tracing (ROBAST), which is aimed for wide use in optical simulations of cosmic-ray (CR) and gamma-ray telescopes. The library is written in C++ and fully utilizes the geometry library of the ROOT analysis framework. Despite the importance of optics simulations in CR experiments, no open-source software for ray-tracing simulations that can be widely used existed. To reduce the unnecessary effort demanded when different research groups develop multiple ray-tracing simulators, we have successfully used ROBAST for many years to perform optics simulations for the Cherenkov Telescope Array (CTA). Among the proposed telescope designs for CTA, ROBAST is currently being used for three telescopes: a Schwarzschild--Couder telescope, one of the Schwarzschild--Couder small-sized telescopes, and a large-sized telescope (LST). ROBAST is also used for the simulations and the development of hexagonal light concentrators that has been proposed for the LST focal plane. By fully utilizing the ROOT geometry library with additional ROBAST classes, building complex optics geometries that are typically used in CR experiments and ground-based gamma-ray telescopes is possible. We introduce ROBAST and show several successful applications for CTA.Comment: In Proceedings of the 34th International Cosmic Ray Conference (ICRC2015), The Hague, The Netherlands. All CTA contributions at arXiv:1508.0589

A Semi-Lagrange Galerkin Method for Shallow Water Equations

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

1/3-harmonic Oscillation in Three-phase Circuit with Series Condensers (II)

The authors deal with the nearly 1/3-harmonic oscillation (a kind of almost periodic oscillation) in three-phase circuit with series condensers. The fundamental equation becomes non-autonomous type with small parameter ε aₖq xq + ε fₖ (z₁, x₂, x₅, τ) k＝1, 2, 3, 4, 5 An analog computer is used for obtaining the parameter region where the nearly 1/3- harmonic oscillation is sustained. Furthermore, the asymptotic method of Bogoliubov and Mitropolsky is extended to analyse the behavior of the nearly 1/3-harmonic oscillation

Analysis of Nonlinear Oscillations in Three-phase Circuits by Discrete Fourier Transform

A method for analysing the nonlinear oscillations in three-phase circuits with nonlinearities of polynomials of a high degree is presented by use of the discrete Fourier transform (DFT). The stability of the oscillation is investigated by means of the DFT. Furthermore, this paper describes how to determine the sampling rate. Numerical examples by the conventional Fourier series method are compared

1/3-harmonic Oscillation in Three-phase Circuit with Series Condensers

The 1/3-harmonic oscillation originated in the three phase circuit with series condensers is treated. The system equation is reduced to the nonautonomous type of nonlinear differential equation aₖᵢxᵢ+εfₖ(x₁, x₂, ···, x₅, τ) k＝l, 2, ···, 5 ε : small parameter First by means of analog computer the 1/3-harmonic oscillation is investigated and then the extended form of Bogoliubov and Mitropolski's asymptotic method for the system with some-degrees of freedom is used for obtaining the periodic solution

A Method for Analysing Parametrically Excited System by Matrix Function

This paper describes a method for analysing parametrically excited system of higher order. The method is based on the theory of matrix function and the discrete Fourier transform. As a numerical example, we deal with a kind of Hill's equation derived from the synchronous generator circuit with unbalanced capacitive load and give its stability charts

Digital Simulation of Hysteretic Loop by Preisach Diagram

This paper proposes a method for a digital simulation of hysteretic loops based on the use of the Preisach diagram. The hysteretic characteristic is expressed by an integral equation the kernel of which is discretely given. As examples, using the method proposed, we obtain the major loop, minor loop and so forth