High-accuracy numerical relativity simulations of binary neutron star mergers are a necessary ingredient for constructing gravitational-waveform templates to analyze and interpret observations compact object mergers. Numerical convergence in the postmerger phase such is challenging achieve with many modern codes. In this paper, we study two ways improving properties merger within Baumgarte-Shap...

We consider semilinear and quasilinear parabolic systems with a nonsmooth rate-independent and a viscous dissipation term in the limit of very slow loading rates, or equivalently with fixed loading and vanishing viscosity " > 0. Because for nonconvex energies the solutions will develop jumps, we consider the vanishing-viscosity limit for the graphs of the solutions in the extended state space i...

The paper deals with a novel method of control system design which applies meromorphic transfer functions as models for retarded linear time delay systems. After introducing an auxiliary state model a finite-spectrum observer is designed to close a stabilizing state feedback. The observer finite spectrum is the key to implement a state feedback stabilization scheme and to apply the affine param...

This paper examines the problem of estimating linear time-invariant state-space system models. In particular it addresses the parametrization and numerical robustness concerns that arise in the multivariable case. These difficulties are well recognised in the literature, resulting (for example) in extensive study of subspace based techniques, as well as recent interest in “data driven” local co...

A variable parametrization scheme is developed and demonstrated for shape optimization using quasi-Newton methods. The scheme performs adaptive parametrization refinement while preserving the approximate Hessian of the shape optimization problem and enables free-form shape design using quasi-Newton optimization methods. Using a Bspline parametrization, the scheme is validated using a 1-D shape ...

A new approach for data-based stochastic parametrization of unresolved scales and processes in numerical weather and climate prediction models is introduced. The subgrid-scale model is conditional on the state of the resolved scales, consisting of a collection of local models. A clustering algorithm in the space of the resolved variables is combined with statistical modelling of the impact of t...

We introduce a parametrization of loop momenta which allows us to perform one of the Feynman integrations in a very transparent way. This leads to expressions which can easily be related to terms resulting from time-ordered perturbation theory in the infinite momentum frame. To exemplify our method we consider some simple Feynman integrals. As another example we discuss the covariant expression...

An analysis of the climate parametrization scheme adopted by conventional forest gap models revealed that most models assume a constant climate and are difficult to calibrate consistently. Tree growth showed unrealistically sensitive threshold effects along ecological gradients of temperature and precipitation. A new parametrization was compared with its predecessors in terms of the model's cap...

In this paper, we revisit the parameterizations of the equation of state of dark energy and point out that comparing merely the χ of different fittings may not be optimal for choosing the ”best” parametrization. Another figure of merit for evaluating different parametrizations based on the area of the w(z) − z band is proposed. In light of the analysis of some two-parameter parameterizations an...

This paper focuses on global stability analysis problems for interconnected nonlinear systems. The main purpose is to introduce a useful parametrization into supply rates of dissipative nonlinear systems for establishing global stability via the Inputto-State Stable(ISS) small-gain condition. Supply rates which are parametrized by state-dependent scaling provide us with convenient flexibility t...