On non-adjointable semi-Weyl and semi-B-Fredholm operators over C*-algebras

We extend further semi-A-Fredholm theory by generalizing the results from classical semi-Weyl theory on Hilbert spaces. Moreover, we obtain an analogue of the results from [17] in the setting of non-adjointable operators. Finally, we provide several examples on semi-A-Fredholm and semi- A-Weyl operators over a unital C*-algebra A. We give also the examples of semi-A-Fredholm operators with non-closed image

On New Approach to Fredholm theory in unital C*-algebras

Motivated by the Fredholm theory on the standard Hilbert module over an unital C*-algebra introduced by Mishchenko and Fomenko, we provide a new approach to axiomatic Fredholm theory in unital C*-algebras established by Keckic and Lazovic in [28]. Our approach is equivalent to the approach introduced by Keckic and Lazovic, however, we provide new proofs which are motivated by the proofs given by Mishchenko and Fomenko

Experimental Study of Diamond Like Carbon (DLC) Coated Electrodes for Pulsed High Gradient Electron Gun

For the SwissFEL Free Electron Laser project at the Paul Scherrer Institute, a pulsed High Gradient (HG) electron gun was used to study low emittance electron sources. Different metals and surface treatments for the cathode and anode were studied for their HG suitability. Diamond Like Carbon (DLC) coatings are found to perform exceptionally well for vacuum gap insulation. A set of DLC coated electrodes with different coating parameters were tested for both vacuum breakdown and photo electron emission. Surface electric fields over 250MV/m (350 - 400kV, pulsed) were achieved without breakdown. From the same surface, it was possible to photo-emit an electron beam at gradients up to 150MV/m. The test setup and the experimental results are presentedComment: 4 pages, 14 figures, IPMHVC 2010 : IEEE International Power Modulator and High Voltage Conferenc

GEAR-RT: Towards Exa-Scale Moment Based Radiative Transfer For Cosmological Simulations Using Task-Based Parallelism And Dynamic Sub-Cycling with SWIFT

The development and implementation of GEAR-RT, a radiative transfer solver using the M1 closure in the open source code SWIFT, is presented, and validated using standard tests for radiative transfer. GEAR-RT is modeled after RAMSES-RT (Rosdahl et al. 2013) with some key differences. Firstly, while RAMSES-RT uses Finite Volume methods and an Adaptive Mesh Refinement (AMR) strategy, GEAR-RT employs particles as discretization elements and solves the equations using a Finite Volume Particle Method (FVPM). Secondly, GEAR-RT makes use of the task-based parallelization strategy of SWIFT, which allows for optimized load balancing, increased cache efficiency, asynchronous communications, and a domain decomposition based on work rather than on data. GEAR-RT is able to perform sub-cycles of radiative transfer steps w.r.t. a single hydrodynamics step. Radiation requires much smaller time step sizes than hydrodynamics, and sub-cycling permits calculations which are not strictly necessary to be skipped. Indeed, in a test case with gravity, hydrodynamics, and radiative transfer, the sub-cycling is able to reduce the runtime of a simulation by over 90%. Allowing only a part of the involved physics to be sub-cycled is a contrived matter when task-based parallelism is involved, and is an entirely novel feature in SWIFT. Since GEAR-RT uses a FVPM, a detailed introduction into Finite Volume methods and Finite Volume Particle Methods is presented. In astrophysical literature, two FVPM methods are written about: Hopkins (2015) have implemented one in their GIZMO code, while the one mentioned in Ivanova et al. (2013) isn't used to date. In this work, I test an implementation of the Ivanova et al. (2013) version, and conclude that in its current form, it is not suitable for use with particles which are co-moving with the fluid, which in turn is an essential feature for cosmological simulations.Comment: PhD Thesi