Analysis of critical motions of floating structures

Validation of numerical methods for describing the motion of a ship in sea conditions by adequate experiments is a major research field in ocean engineering. For the development of a method for the systematic determination of critical and safe operational conditions and for the classification of capsize scenarios bifurcation analyses are performed. The computational effort for these analyses is enormous using a full model describing the nonlinear dynamics of a floating body. Therefore, a method for model reduction is currently being developed at the Institute of Mechanics and Ocean Engineering at TUHH. Bases for the validation of this new method are experiments conducted in the institute's wave tank. The determination of position and attitude of the body is performed with an integrated measurement system: An inertial measurement unit and a video system are combined using an extended Kalman Filter. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Phase-field simulation of the electro-mechanical response of ferroelectrics during Piezoresponse Force Microscopy

The contribution adresses the simulation of ferroelectric matrials in the framework of the Piezoresponse Force Microscopy (PFM). Based on the PFM, ferroelectric domain structures can be analyzed in great detail by measuring the electrically induced mechanical deformations of the surface of a ferroelectric. We employ a flexible continuum-mechanical model based on the phase-field method in order to analyze the behavior of ferroelectric microstructures numerically. Since ferroelectric materials are often highly anisotropic, the phase-field formulation will account for transversely isotropic symmetry. (© 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Two-dimensional Fourier transform ion cyclotron resonance mass spectrometry: reduction of scintillation noise using Cadzow data processing

In two-dimensional Fourier transform ion cyclotron resonance mass spectrometry (2D FTICR-MS), scintillation noise, caused mostly by fluctuations in the number of ions in the ICR cell, is the leading cause for errors in spectrum interpretation. In this study, we adapted an algorithm based on singular value decomposition and first introduced by Cadzow et al. (IEE Proceedings Pt. F 1987, 134, 69) to 2D FTICR-MS and we measured its performance in terms of noise reduction without losing signal information in the 2D mass spectrum.     

On the generation of soft magneto-electric effects through Maxwell interactions

This contribution presents a finite-strain computational homogenization framework for soft magneto-electro-elastic solids. We use it in order to determine effective magneto-electric coupling coefficients of soft composites, which are driven by the interconnection of electrical and magnetical Maxwell stresses. (© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Oxidative 1,2- and 1,3-alkyl shift processes: developments and applications in synthesis

Oxidative 1,2- and 1,3- alkyl shifts mediated by a hypervalent iodine reagent were performed on simple and inexpensive phenol derivatives. These transpositions enable rapid redesign of the main aromatic skeleton to generate good yields of highly functionalized scaffolds containing a prochiral dienone system, a quaternary carbon center connected to as many as four sp(2) centers, and a carbonyl functionality or precursor. An efficient enantioselective version of this process resulting in the formation of a challenging quaternary carbon center is also described. The products represent the central cores of several natural products having important bioactivities. As an illustration of the potential of this method, we describe the rapid synthesis of several functionalized polycyclic systems as well as a formal synthesis of acetylaspidoalbidine, a hexacyclic alkaloid belonging to the Aspidosperma family.     

CRAACK: consensus program for NMR amino acid type assignment

Protein peak spectrum assignment is a prerequisite of the nuclear magnetic resonance study of a molecule. We present here a computer tool which proposes the determination of the amino acid type from the values of the chemical shifts. This tool is based on two consensus algorithms based on several published typing algorithms and was trained and extensively tested against the Biological Magnetic Resonance Bank chemical shift data bank. The first one accomplishes the analysis with support vector machine technology, grouping related amino acids together, and presents a mean rate of success above 90% on the test set. The second one uses a classical consensus algorithm of vote. Furthermore, secondary structural prediction is available. This tool can be used for assisting manual assignment of peptides and proteins and can also be used as a step in an automated approach to assignment. This program has been called CRAACK and is publicly available at the following URL: http://abcis.cbs.cnrs.fr/craack.     

Phase-field simulation of piezoresponse force microscopy in consideration of different environmental conditions

Piezoresponse force microscopy (PFM) is a feasible tool which is widely used for investigating information of the domain structures of ferroelectrics. Nevertheless, one drawback of the technique may be that environmental conditions could effect the very small signal which is detected from the displacement of the tip. The present contribution addresses the simulation of PFM in consideration of environmental conditions. We employ a continuum-mechanical model based on the phase-field method which accounts for the transversely isotropic symmetry of the underlying material. The goal of this contribution is to analyze the environmental effect on the tip-sample interaction. (© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)