Proven angular bounds and stretched triangulations with the frontal Delaunay method

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76717/1/AIAA-1993-3347-182.pd

Quark spectral properties above Tc from Dyson-Schwinger equations

We report on an analysis of the quark spectral representation at finite temperatures based on the quark propagator determined from its Dyson-Schwinger equation in Landau gauge. In Euclidean space we achieve nice agreement with recent results from quenched lattice QCD. We find different analytical properties of the quark propagator below and above the deconfinement transition. Using a variety of ansaetze for the spectral function we then analyze the possible quasiparticle spectrum, in particular its quark mass and momentum dependence in the high temperature phase. This analysis is completed by an application of the Maximum Entropy Method, in principle allowing for any positive semi-definite spectral function. Our results motivate a more direct determination of the spectral function in the framework of Dyson-Schwinger equations

Algorithm Developments for Discrete Adjoint Methods

This paper presents a number of algorithm developments for adjoint methods using the 'discrete' approach in which the discretisation of the non-linear equations is linearised and the resulting matrix is then transposed. With a new iterative procedure for solving the adjoint equations, exact numerical equivalence is maintained between the linear and adjoint discretisations. The incorporation of strong boundary conditions within the discrete approach is discussed, as well as a new application of adjoint methods to linear unsteady flow in turbomachinery

Wing-body junction optimisation with CAD-based parametrisation including a moving intersection

Over the past decades significant progress has been made with adjoint computational fluid dynamics solvers, which are an essential part of efficient high-fidelity aerodynamic shape optimisation. Shape parametrisation is much less mature, in particular the field is lacking efficient and automatic CAD-based parametrisation methods. The paper proposes a novel CAD-based parametrisation with CAD in the design loop such that the CAD shape can ultimately serve as a datum surface in multi-disciplinary optimisation. Wing and fuselage are modelled with B-spline surfaces. The intersection line is calculated using an in-house implementation of a B-spline surface modeller and its derivative is efficiently calculated via finite differences. The proposed parametrisation method is applied to the redesign of the wing–fuselage junction of the DLR-F6 model using an adjoint solver based on Reynolds-averaged Navier–Stokes equations. The moving intersection line capability enables the fuselage surface to be deformed and the resulting intersection line to move along the fixed wing during optimisation. The flow separation in the wing–body junction is substantially suppressed by an improved fuselage shape, at the cost of O(10) steady-state flow and adjoint solutions. The proposed parametrisation method represents an important step towards automated CAD-based optimisation for fully-featured aircraft characterised by complex intersecting surfaces

Computations of inviscid compressible flows using fluctuation-splitting on triangular meshes

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/77018/1/AIAA-1993-3301-532.pd

An object-oriented approach to hybrid structured/unstructured grid generation

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/77270/1/AIAA-1996-32-959.pd

The relentless variability of Mrk 421 from the TeV to the radio

The origin of the gamma-ray emission of the blazar Mrk 421 is still a matter of debate. We used 5.5 years of unbiased observing campaign data, obtained using the FACT telescope and the Fermi LAT detector at TeV and GeV energies, the longest and densest so far, together with contemporaneous multi-wavelength observations, to characterise the variability of Mrk 421 and to constrain the underlying physical mechanisms. We studied and correlated light curves obtained by ten different instruments and found two significant results. The TeV and X-ray light curves are very well correlated with a lag of <0.6 days. The GeV and radio (15 Ghz band) light curves are widely and strongly correlated. Variations of the GeV light curve lead those in the radio. Lepto-hadronic and purely hadronic models in the frame of shock acceleration predict proton acceleration or cooling timescales that are ruled out by the short variability timescales and delays observed in Mrk 421. Instead the observations match the predictions of leptonic models.Comment: 10 pages, 8 figures, 1 tabl

DNA methylation-based classification of central nervous system tumours.

Accurate pathological diagnosis is crucial for optimal management of patients with cancer. For the approximately 100 known tumour types of the central nervous system, standardization of the diagnostic process has been shown to be particularly challenging-with substantial inter-observer variability in the histopathological diagnosis of many tumour types. Here we present a comprehensive approach for the DNA methylation-based classification of central nervous system tumours across all entities and age groups, and demonstrate its application in a routine diagnostic setting. We show that the availability of this method may have a substantial impact on diagnostic precision compared to standard methods, resulting in a change of diagnosis in up to 12% of prospective cases. For broader accessibility, we have designed a free online classifier tool, the use of which does not require any additional onsite data processing. Our results provide a blueprint for the generation of machine-learning-based tumour classifiers across other cancer entities, with the potential to fundamentally transform tumour pathology