Volkan Akcelik

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For earthquake simulations to play an important role in the reduction of seismic risk, they must be capable of high resolution and high fidelity. We have developed algorithms and tools for earthquake simulation based on multiresolution hexahedral meshes. We have used this capability to carry out 1 Hz simulations of the 1994 Northridge earthquake in the LA(More)
Work supported by the U.S. DOE ASCR, BES, and HEP Divisions under contract No. DE-AC02-76SF00515. The work used the resources of NCCS at ORNL which is supported by the Office of Science of the U.S. DOE under Contract No. DE-AC05-00OR22725, and the resources of NERSC at LBNL which is supported by the Office of Science of the U.S. DOE under Contract No.(More)
One of the outstanding challenges of computational science and engineering is large-scale nonlinear parameter estimation of systems governed by partial differential equations. These are known as <i>inverse problems</i>, in contradistinction to the <i>forward problems</i> that usually characterize large-scale simulation. Inverse problems are significantly(More)
In contrast to traditional terascale simulations that have known, fixed data inputs, dynamic data-driven (DDD) applications are characterized by unknown data and informed by dynamic observations. DDD simulations give rise to inverse problems of determining unknown data from sparse observations. The main difficulty is that the optimality system is a boundary(More)
Nearly Orthogonal Two-Dimensional Grid Generation with Aspect Ratio Control Volkan Akcelik,∗ Branislav Jaramaz,†,‡ and Omar Ghattas∗ ∗Laboratory for Mechanics, Algorithms, and Computing, Department of Civil and Environmental Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania; †Center for Orthopaedic Research, UPMC Shadyside Hospital,(More)
We are interested in a DDDAS problem of localization of airborne contaminant releases in regional atmospheric transport models from sparse observations. Given measurements of the contaminant over an observation window at a small number of points in space, and a velocity field as predicted for example by a mesoscopic weather model, we seek an estimate of the(More)
∗ Work supported by the U.S. Department of Energy ASCR, BES and HEP Divisions under contract No. DE-AC02-76SF00515. Abstract The successful operation of accelerator cavities has to satisfy both rf and mechanical requirements. It is highly desirable that electromagnetic, thermal and structural effects such as cavity wall heating and Lorentz force detuning in(More)
PDE-constrained optimization refers to the optimization of systems governed by partial differential equations (PDEs). The simulation problem is to solve the PDEs for the state variables (e.g. displacement, velocity, temperature, electric field, magnetic field, species concentration), given appropriate data (e.g. geometry, coefficients, boundary conditions,(More)
The measured physical parameters of a superconducting cavity differ from those of the designed ideal cavity. This is due to shape deviations caused by both loose machine tolerances during fabrication and by the tuning process for the accelerating mode. We present a shape determination algorithm to solve for the unknown deviations from the ideal cavity using(More)