In the context of time-domain simulation integrated circuits, one often encounters large systems coupled differential-algebraic equations. Simulation costs these can become prohibitively as number components keeps increasing. an effort to reduce a twofold approach is presented in this paper. We combine maximum entropy snapshot sampling method and nonlinear model order reduction technique, with ...

Numerical reservoir simulation models are used in the energy industry to forecast the behavior of hydrocarbon reservoirs and connected surface facilities over long production periods. The simulation of oil and gas reservoirs requires the construction and solution of large, sparse linear systems with millions or tens of millions of unknowns at each step of a Newton iteration. The problem size an...

The European Space Agency (ESA) X-ray Evolving Universe Spectroscopy (XEUS) mission is designed as a follow-on to the ESA X-ray Multi Mirror (XMM-Newton) mission and may contain charge-coupled device (CCD) based instrumentation. Low instrument background is essential for the mission to maximise sensitivity. Results from XMM-Newton and the Japanese Space Agency Suzaku mission show that both the ...

We have identified three possible ways in which future XMM-Newton observations can provide significant constraints on the equation of state of neutron stars. First, using a long observation of the neutron star X-ray transient Cen X–4 in quiescence one can use the RGS spectrum to constrain the interstellar extinction to the source. This removes this parameter from the X-ray spectral fitting of t...

A two-dimensional Newton–Krylov aerodynamic shape optimization algorithm is applied to several optimization problems in which the location of laminar-turbulent transition is free. The coupled Euler and boundary-layer solver MSES is used to obtain transition locations through the e method, which are then used in Optima2D, a Newton–Krylov discrete-adjoint optimization algorithm based on the compr...

In this paper, the Newton-conjugate-gradient methods are developed for solitary wave computations. These methods are based on Newton iterations, coupled with conjugategradient iterations to solve the resulting linear Newton-correction equation. When the linearization operator is self-adjoint, the preconditioned conjugate-gradient method is proposed to solve this linear equation. If the lineariz...

Fluid–structure interaction (FSI) can be simulated in a monolithic way by solving the flow and structural equations simultaneously and in a partitioned way with separate solvers for the flow equations and the structural equations. A partitioned quasi-Newton technique which solves the coupled problem through nonlinear equations corresponding to the interface position is presented and its perform...

Spectral residual methods are derivative-free and low-cost per iteration procedures for solving nonlinear systems of equations. They generally coupled with a nonmonotone linesearch strategy compare well Newton-based large sequences systems. The vector is used as the search direction choosing steplength has crucial impact on performance. In this work we address both theoretically experimentally ...

We present an X-ray study of our nearest starburst galaxy IC 10, based on XMM-Newton and Chandra observations. A list of 73 XMM-Newton and 28 Chandra detections of point-like X-ray sources in the field is provided; a substantial fraction of them are likely stellar objects in the Milky Way due to the low Galactic latitude location of IC 10. The brightest source in the IC 10 field, X-1, has a mea...

We report on a detailed study of the X-ray spectrum of the nearby eclipsing spectroscopic binary YY Gem. Observations were obtained simultaneously with both large X-ray observatories, XMM-Newton and Chandra. We compare the high-resolution spectra acquired with the Reflection Grating Spectrometer onboard XMM-Newton and with the Low Energy Transmission Grating Spectrometer onboard Chandra, and ev...