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Variant-based competitive parallel execution of sequential programs
(2010)Technical ReportCompetitive parallel execution (CPE) is a simple yet attractive technique to improve the performance of sequential programs on multi-core and multi-processor systems. A sequential program is transformed into a CPE-enabled program by introducing multiple variants for parts of the program. The performance of different variants depends on runtime conditions, such as program input or the execution platform, and the execution time of a CPE-enabled ...Report -
Ein neuer Ansatz für standardisierte Ganglinien
(2010)Arbeitsberichte Verkehrs- und RaumplanungStandardisierte Ganglinien sind eine wesentliche Grundlage für viele Bemessungsverfahren des Verkehrswesens. Die gängige Praxis, deren Dynamik in Tages-, Wochen- und Monatsganglinien zu zerlegen, erzeugt Verzerrungen, insbesondere für Montage und Freitage. Die Praxis querschnittsorientierte Ganglinien auszuweisen entfernt weitere wichtige Details. Im Rahmen der Neuerstellung der relevanten Schweizer Norm wurden diese beiden Ansätze verworfen ...Working Paper -
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Advice complexity and barely random algorithms
(2010)Technical reportRecently, a new measurement – the advice complexity – was introduced for measuring the information content of online problems. The aim is to measure the bitwise information that online algorithms lack, causing them to perform worse than offline algorithms. Among a large number of problems, a well-known scheduling problem, job shop scheduling with unit length tasks, and the paging problem were analyzed within this model. We observe some ...Report -
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Sparse tensor spherical harmonics approximation in radiative transfer
(2010)SAM Research ReportThe stationary monochromatic radiative transfer equation is a partial differential transport equation stated on a five-dimensional phase space. To obtain a well-posed problem, inflow boundary conditions have to be prescribed. The sparse tensor product discretization has been successfully applied to finite element methods in radiative transfer with wavelet discretization of the angular domain (Widmer2009a). In this report we show that the ...Report -
hp-FEM for second moments of elliptic PDEs with stochastic data Part 1: Analytic regularity
(2010)SAM Research ReportFor a linear second order elliptic partial differential operator $A: V → V'$, we consider the boundary value problems $Au=f$ with stationary Gaussian random data $f$ over the dual $V'$ of the separable Hilbert space $V$ in which the solution u is sought. The operator $A$ is assumed to be deterministic and bijective. The unique solution $u= A^-$$^1f $ is a Gaussian random field over $V$. It is characterized by its mean field $E_u$ and ...Report -
hp-FEM for second moments of elliptic PDEs with stochastic data Part 2: Exponential convergence
(2010)SAM Research ReportWe prove exponential rates of convergence of a class of $hp$ Galerkin Finite Element approximations of solutions to a model tensor non-hypoelliptic equation in the unit square □ = (0,1)$^2$ which exhibit singularities on ∂□ and on the diagonal ∆ = {($x,y$) ∈ □ : $x$ = $y$}, but are otherwise analytic in □. As we explained in the first part [6] of this work, such problems arise as deterministic second moment equations of linear, second ...Report