Resonance enhancement by suitably chosen frequency detuning

In this Letter we report new effects of resonance detuning on various dynamical parameters of a generic 3-wave system. Namely, for suitably chosen values of detuning the variation range of amplitudes can be significantly wider than for exact resonance. Moreover, the range of energy variation is not symmetric with respect to the sign of the detuning. Finally, the period of the energy oscillation exhibits non-monotonic dependency on the magnitude of detuning. These results have important theoretical implications where nonlinear resonance analysis is involved, such as geophysics, plasma physics, fluid dynamics. Numerous practical applications are envisageable e.g. in energy harvesting systems.Comment: 13 pages, 6 figures, 5 references. Other author's papers can be viewed at http://www.denys-dutykh.com

Extended Abstract: Analysis of 1000 Arbiter PUF based RFID Tags

In this extended abstract a large-scale analysis of 4- way Arbiter PUFs is performed with measurement results from 1000 RFID tags. Arbiter PUFs are one of the most important building blocks in PUF-based protocols and have been the subject of many papers. However, in the past often only software simulations or a limited number of test chips were available for analysis. Therefore, the goal of this work is to verify earlier findings in regard to the uniqueness and reliability of Arbiter PUFs by using a much larger measurement set. Furthermore, we used machine learning algorithms to approximate and compare the internal delay differences of the employed PUF. One of the main research questions in this paper is to examine if any “outliers” occurred, i.e., if some tags performed considerably different. This might for example happen due to some unusual manufacturing variations or faults. However, our findings are that for all of the analyzed tags the parameters fell within the range of a Gaussian distribution without significant outliers. Hence, our results are indeed in line with the results of prior work

Tungsten imido-catalysed dimerisation of α-olefins: insight into the Lewis acid's function revealed from computational studies

AbstractAlternative channels of the tungsten imido-catalysed olefin dimerisation proceeding through mono(imido) and bis(imido) compounds have been examined by means of the DFT method simulating authentic reaction conditions on catalyst models that closely mimic the real catalyst system. All relevant steps of a plausible metallacycle mechanism to follow alternative pathways together with the divergent path towards azatungstanacycle intermediates have been characterised by considering up to three AlClMe2 moieties explicitly. This study disclosed that the Lewis acid is actively engaged in the productive catalytic cycle, this in addition to its presumed role, among others, as alkylating and chloride ligand abstraction agent in the formation of the active catalyst species. The Lewis acid preferably forms four-membered chelates across tungsten–imido or tungsten–chlorine bonds featuring a μ-Al–Cl–W bridge. The formation of the five-membered tungstanacycle is found to be less affected by the cocatalyst, but it acts profoundly in modulating the energetics of its degradation into the dimer product. DFT predicts a smooth energy profile for the most accessible path via mono(imido) tungsten species, having the Lewis acid bridged across tungsten–chlorine bonds, which is in consonance with observed activity and selectivity. This type of Lewis acid association appears as being pivotal for an effective catalysis. The alternative channel to engage bis(imido) tungsten compounds features significantly more demanding kinetics for the dimer generating route, thereby rendering it as being almost impossible to be accessed. The present study constitutes evidence, based on reliable DFT calculations, that mono(imido) tungsten compounds complexed by the Lewis acid component is effectively triggering dimerisation, whilst bis(imido) tungsten species are unlikely to play a role in the productive cycle

Formation of the dynamic energy cascades in quartic and quintic generalized KdV equations

25 pages, 11 figures, 3 tables, 29 references. Other author's papers can be downloaded at http://www.denys-dutykh.com/In this study we investigate the formation of dynamical energy cascades in higher order KdV-type equations. In the beginning we recall what is known about the dynamic cascades for the classical KdV (quadratic) and mKdV (cubic) equations. Then, we investigate further the mKdV case by considering a richer set of initial perturbations in order to check the validity and persistence of various facts previously established for the narrow-banded perturbations. Afterwards we focus on higher order nonlinearities (quartic and quintic) which are found to be quite different in many respects from the mKdV equation. Throughout this study we consider both the direct and double energy cascades. It was found that the dynamic cascade is always formed, but its formation is not necessarily accompanied by the nonlinear stage of the modulational instability. Direct cascade structure remains invariant regardless the size of the spectral domain. In contrast, the double cascade shape can depend on the size of the spectral domain, even if the total number of cascading modes remains invariant. Results obtained in this study can be potentially applied to plasmas, free surface and internal wave hydrodynamics

Verbesserung der Jugendentwicklung von Sojabohnen durch Priming und Saatbeigaben

Das übergeordnete Ziel des Vorhabens ist, eine zügige und kräftige Jugendentwicklung von Sojabohnen durch Priming (vorquellen in Wasser) und Saatbeigaben zu erzielen und in ein praxisreifes Verfahren zu überführen. Beide Strategien werden bereits bei anderen Kulturen in der Praxis erfolgreich genutzt und die Wirkungen sind wissenschaftlich belegt. In verschiedenen Gefäß- und Keimversuchen wurden verschiedene Primingdauern und verschiedene Saatbeigabenpräparate getestet. In einem anschließenden 2-jährigen Feldversuch wurde die „beste“ Primingdauer (12 Stunden) sowie die beste Saatbeigabe (Mykoplant) untersucht. Dabei wurde das Jugendwachstum sowie die weitere Pflanzenentwicklung bis zur Ernte erfasst. Es hat sich gezeigt, dass die gewählte Art des Hydroprimings, sowie verschiedene Varianten davon, in Sojabohnen zu einer Reduzierung der Keimfähigkeit führt und das Jugendwachstum eher negativ als positiv beeinflusst. Bei den Saatbeigaben konnten z.T. positive Wirkungen gezeigt werden, allerdings sind diese zu gering für eine Praxisrelevanz. Die Ergebnisse wurden auf zahlreichen Fachtagungen als Poster oder Vortrag vorgestellt und mit anderen Wissenschaftlern diskutiert. Der Feldversuch wurde in beiden Jahren im Rahmen von Feldtagen präsentiert und besprochen. Im Rahmen des Projektes konnten eine Bachelor- sowie eine Masterarbeit realisiert werden. Eine systematische Literaturauswertung soll die bisher veröffentlichten Arbeiten zum Thema Hydropriming in Sojabohnen umfassend und quantitativ auswerten und so zu einem erheblichen Erkenntnisgewinn in diesem Bereich beitragen