Three new synonymies in \u3ci\u3ePhyllophaga\u3c/i\u3e Harris, 1827 (Coleoptera: Scarabaeidae), with lectotype and neotype designations

In the course of working on new species of North American Phyllophaga Harris, 1827 (Coleoptera: Scarabaeidae: Melolonthinae) some synonyms have been found and are proposed here. New synonymies: Phyllophaga knausii (Schaeffer, 1907) is synonymized with Phyllophaga sociata (Horn, 1878); Phyllophaga chippewa Saylor, 1939 is synonymized with Phyllophaga rugosa (Melsheimer, 1845); and Phyllophaga falta Sanderson, 1950 is synonymized with Phyllophaga bipartita (Horn, 1887). Lectotypes are here designated for the following species: Listrochelus knausii Schaeffer, Listrochelus sociatus Horn, and Lachnosterna bipartita Horn. A neotype for Ancylonycha rugosa Melsheimer is here designated from the Horn Collection

Extension of the Finite Integration Technique including dynamic mesh refinement and its application to self-consistent beam dynamics simulations

An extension of the framework of the Finite Integration Technique (FIT) including dynamic and adaptive mesh refinement is presented. After recalling the standard formulation of the FIT, the proposed mesh adaptation procedure is described. Besides the linear interpolation approach, a novel interpolation technique based on specialized spline functions for approximating the discrete electromagnetic field solution during mesh adaptation is introduced. The standard FIT on a fixed mesh and the new adaptive approach are applied to a simulation test case with known analytical solution. The numerical accuracy of the two methods are shown to be comparable. The dynamic mesh approach is, however, much more efficient. This is also demonstrated for the full scale modeling of the complete RF gun at the Photo Injector Test Facility DESY Zeuthen (PITZ) on a single computer. Results of a detailed design study addressing the effects of individual components of the gun onto the beam emittance using a fully self-consistent approach are presented.Comment: 33 pages, 14 figures, 4 table

NCLab: Public Computing Laboratory

This survey paper describes the Network Computing Laboratory (NCLab), a novel public cloud computing platform for mathematics, programming, scientific computing and computer simulations. Through a web-browser interface, it provides users with free access to interactive graphical modules that include symbolic and numerical methods, programming in several languages, computing with Python scientific libraries, computing with GNU Octave, GPU computing with CUDA, computational geometry, 3D CAD design, computational graph theory, finite element programming with the Hermes library, and interactive graphical finite element modules. Users can upload files and data from their local computers, clone projects from the database, share files, form teams, and collaborate on projects. This paper briefly describes how NCLab operates, and it provides concise descriptions of NCLab computational modules with examples of us

A flexible one-pot route to metal/metal oxide nanocomposites

We report a one-pot route to Au/CeO2 nanocomposites. A readily-available biopolymer, sodium alginate, is exploited for controlled formation and stabilisation of gold nanoparticles followed by in situ growth of a sponge-like network of CeO2 nanoparticles. The flexible nature of this method as a general route to mixed metal/metal oxide nanocomposites is also demonstrated

A Space-Time Discontinuous Galerkin Trefftz Method for time dependent Maxwell's equations

We consider the discretization of electromagnetic wave propagation problems by a discontinuous Galerkin Method based on Trefftz polynomials. This method fits into an abstract framework for space-time discontinuous Galerkin methods for which we can prove consistency, stability, and energy dissipation without the need to completely specify the approximation spaces in detail. Any method of such a general form results in an implicit time-stepping scheme with some basic stability properties. For the local approximation on each space-time element, we then consider Trefftz polynomials, i.e., the subspace of polynomials that satisfy Maxwell's equations exactly on the respective element. We present an explicit construction of a basis for the local Trefftz spaces in two and three dimensions and summarize some of their basic properties. Using local properties of the Trefftz polynomials, we can establish the well-posedness of the resulting discontinuous Galerkin Trefftz method. Consistency, stability, and energy dissipation then follow immediately from the results about the abstract framework. The method proposed in this paper therefore shares many of the advantages of more standard discontinuous Galerkin methods, while at the same time, it yields a substantial reduction in the number of degrees of freedom and the cost for assembling. These benefits and the spectral convergence of the scheme are demonstrated in numerical tests

Discontinuous Galerkin Methods with Trefftz Approximation

We present a novel Discontinuous Galerkin Finite Element Method for wave propagation problems. The method employs space-time Trefftz-type basis functions that satisfy the underlying partial differential equations and the respective interface boundary conditions exactly in an element-wise fashion. The basis functions can be of arbitrary high order, and we demonstrate spectral convergence in the \Lebesgue_2-norm. In this context, spectral convergence is obtained with respect to the approximation error in the entire space-time domain of interest, i.e. in space and time simultaneously. Formulating the approximation in terms of a space-time Trefftz basis makes high order time integration an inherent property of the method and clearly sets it apart from methods, that employ a high order approximation in space only.Comment: 14 pages, 12 figures, preprint submitted at J Comput Phy