Casus

Ecvet Şeci'nin Saadet'te tefrika edilen Casus adlı romanıTefrikanın devamına rastlanmamış, tefrika yarım kalmıştır

Accelerating magnetic induction tomography‐based imaging through heterogeneous parallel computing

Magnetic Induction Tomography (MIT) is a non‐invasive imaging technique, which has applications in both industrial and clinical settings. In essence, it is capable of reconstructing the electromagnetic parameters of an object from measurements made on its surface. With the exploitation of parallelism, it is possible to achieve high quality inexpensive MIT images for biomedical applications on clinically relevant time scales. In this paper we investigate the performance of different parallel implementations of the forward eddy current problem, which is the main computational component of the inverse problem through which measured voltages are converted into images. We show that a heterogeneous parallel method that exploits multiple CPUs and GPUs can provide a high level of parallel scaling, leading to considerably improved runtimes. We also show how multiple GPUs can be used in conjunction with deal.II, a widely‐used open source finite element library

Finite Element Simulation of Wave Propagation in Periodic Piezoelectric SAW Structures

Abstract — Many surface acoustic wave (SAW) devices consist of quasiperiodic structures which are designed by successive repetition of a base cell. The precise numerical simulation of such devices including all physical effects is currently beyond the capacity of high end computation. Therewith, we have to restrict the numerical analysis to the periodic substructure. By using the finite element method (FEM), this can be done by introducing special boundaries, so called periodic boundary conditions (PBCs). To be able to describe the complete dispersion behavior of waves including damping effects, the PBC has to be able to model each mode which can be excited within the periodic structure. Therefore, the condition used for the PBCs must hold for each phase and amplitude difference existing at periodic boundaries. Based on the Floquet theorem, this criteria is fulfilled by our two newly developed PBC algorithms. In the first part of this paper we describe the basic theory of the PBCs. Based on the FEM, we develop two different methods which allow the calculation of phase and attenuation constants of waves propagating on periodic structures. Further on, we show how to compute the charge distribution of periodic SAW structures with the aid of the new PBCs. In the second part, we compare the measured and simulated dispersion behavior of waves propagating on periodic SAW structures on two different piezoelectric substrates. Finally, we compare measured and simulated input admittances of structures similar to SAW resonators. I

Recent Progress in the Consistent Interpretation of Complementary Spectroscopic Results Obtained on Molecular Systems

Abstract Research on organic thin films is largely driven by potential (opto‐)electronic applications and turns out to be no less intriguing from a fundamental point of view. Numerous studies make it clear that the understanding of device‐relevant molecular thin film architectures is quite challenging—often hampered by insufficient spectroscopic data and the lack of a consistent interpretation of the available datasets. Consequently, speculative aspects prevail in the discussion of energy levels in conjunction with the optical properties of organic thin films. Adequate spectroscopic techniques applicable to thin films of organic molecules (typical thicknesses required for devices are in the nanometer range) with the necessary sensitivities are rather demanding. Some of those methods were developed or significantly improved in the recent past. Here, the now available complementary spectroscopies are briefly surveyed with particular emphasis on some techniques that have not yet become widespread standards, and a non‐exhaustive set of examples of acquired experimental results are provided. For a consistent interpretation of the latter, the concepts brought forward in the literature considering the role of initial and final states of spectroscopic processes are outlined, with important consequences for quantitatively correct energy diagrams

Polynomial Eigenvalue Problems: Theory, Computation, and Structure

Matrix polynomial eigenproblems arise in many application areas, both directly and as approximations for more general nonlinear eigenproblems. One of the most common strategies for solving a polynomial eigenproblem is via a linearization, which replaces the matrix polynomial by a matrix pencil with the same spectrum, and then computes with the pencil. Many matrix polynomials arising from applications have additional algebraic structure, leading to symmetries in the spectrum that are important for any computational method to respect. Thus it is useful to employ a structured linearization for a matrix polynomial with structure. This essay surveys the progress over the last decade in our understanding of linearizations and their construction, both with and without structure, and the impact this has had on numerical practice