115 research outputs found
Basin stability approach for quantifying responses of multistable systems with parameters mismatch
Acknowledgement This work is funded by the National Science Center Poland based on the decision number DEC-2015/16/T/ST8/00516. PB is supported by the Foundation for Polish Science (FNP).Peer reviewedPublisher PD
Controlling multistability in coupled systems with soft impacts
This work has been supported by Lodz University of Technology own Scholarship Fund (PB) and by Stipend for Young Outstanding Scientists from Ministry of Science and Higher Education of Poland (PP). PB is supported by the Foundation for Polish Science (FNP).Peer reviewedPostprin
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Sample-based approach can outperform the classical dynamical analysis - Experimental confirmation of the basin stability method
In this paper we show the first broad experimental confirmation of the basin stability approach. The basin stability is one of the sample-based approach methods for analysis of the complex, multidimensional dynamical systems. We show that investigated method is a reliable tool for the analysis of dynamical systems and we prove that it has a significant advantages which make it appropriate for many applications in which classical analysis methods are difficult to apply. We study theoretically and experimentally the dynamics of a forced double pendulum. We examine the ranges of stability for nine different solutions of the system in a two parameter space, namely the amplitude and the frequency of excitation. We apply the path-following and the extended basin stability methods (Brzeski et al., Meccanica 51(11), 2016) and we verify obtained theoretical results in experimental investigations. Comparison of the presented results show that the sample-based approach offers comparable precision to the classical method of analysis. However, it is much simpler to apply and can be used despite the type of dynamical system and its dimensions. Moreover, the sample-based approach has some unique advantages and can be applied without the precise knowledge of parameter values
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Shake table testing of a tuned mass damper inerter (Tmdi)-equipped structure and nonlinear dynamic modeling under harmonic excitations
This paper presents preliminary experimental results from a novel shaking table testing campaign investigating the dynamic response of a two-degree-of-freedom (2DOF) physical specimen with a grounded inerter under harmonic base excitation and contributes a nonlinear dynamic model capturing the behavior of the test specimen. The latter consists of a primary mass connected to the ground through a high damping rubber isolator (HDRI) and a secondary mass connected to the primary mass through a second HDRI. Further, a flywheel-based rack-and-pinion inerter prototype device is used to connect the secondary mass to the ground. The resulting specimen resembles the tuned mass damper inerter (TMDI) configuration with grounded inerter analytically defined and numerically assessed by the authors in a number of previous publications. Physical specimens with three different inerter coefficients are tested on the shake table under sine-sweep excitation with three different amplitudes. Experimental frequency response functions (FRFs) are derived manifesting a softening nonlinear behavior of the specimens and enhanced vibration suppression with increased inerter coefficient. Further, a 2DOF parametric nonlinear model of the specimen is established accounting for non-ideal inerter device behavior and its potential to characterize experimental response time-histories, FRFs, and force-displacement relationships of the HDRIs and of the inerter is verified
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Erratum: Sample-based approach can outperform the classical dynamical analysis - experimental confirmation of the basin stability method
The original version of this Article contained a typographical error in the spelling of the author T. Kapitaniak, which was incorrectly given as T. Kapitaniakenglish. This has now been corrected in the PDF and HTML versions of the Article
Dynamical response of a rocking rigid block
This is the author accepted manuscript. The final version is available from AIP Publishing via the DOI in this recordData accessibility: The data that support the findings of this study are available from the corresponding author upon reasonable request.This paper investigates the complex dynamical behavior of a rigid block structure under
harmonic ground excitation, thereby mimicking, for instance, the oscillation of the system under seismic excitation or containers placed on a ship under periodic acting of sea
waves. The equations of motion are derived assuming a large frictional coefficient at the
interface between the block and the ground, in such a way that sliding cannot occur. In
addition, the mathematical model assumes a loss of kinetic energy when an impact with
the ground takes place. The resulting mathematical model is then formulated and studied in the framework of impulsive dynamical systems. Its complex dynamical response
is studied in detail using two different approaches, based on direct numerical integration
and path-following techniques, the latter implemented via the continuation platform COCO
(Dankowicz & Schilder). Our study reveals the presence of various dynamical phenomena,
such as branching points, fold and period-doubling bifurcation of limit cycles, symmetric
and asymmetric periodic responses, as well as chaotic motion. By using basin stability
method we also investigate the properties of solutions and their ranges of existence in
phase and parameters spaces. Moreover, the study considers ground excitation conditions
leading to the overturning of the block structure and shows parameters regions wherein
such behavior can be avoidedEngineering and Physical Sciences Research Council (EPSRC)National Science Centre, Polan
Hidden evidence of non-exponential nuclear decay
The framework to describe natural phenomena at their basics being quantum
mechanics, there exist a large number of common global phenomena occurring in
different branches of natural sciences. One such global phenomenon is
spontaneous quantum decay. However, its long time behaviour is experimentally
poorly known. Here we show, that by combining two genuine quantum mechanical
results, it is possible to infer on this large time behaviour, directly from
data. Specifically, we find evidence for non-exponential behaviour of alpha
decay of 8Be at large times from experiments.Comment: 12 pages LaTex, 3 figure
Reviving ghost alleles: Genetically admixed coyotes along the American Gulf Coast are critical for saving the endangered red wolf
The last known red wolves were captured in southwestern Louisiana and eastern Texas in 1980 to establish a captive breeding population. Before their extirpation, gene flow with coyotes resulted in the persistence of endangered red wolf genetic variation in local coyote populations. We assessed genomic ancestry and morphology of coyotes in southwestern Louisiana. We detected that 38 to 62% of the coyote genomes contained red wolf ancestry acquired in the past 30 years and have an admixture profile similar to that of the canids captured before the extirpation of red wolves. We further documented a positive correlation between ancestry and weight. Our findings highlight the importance of hybrids and admixed genomes as a reservoir of endangered species ancestry for innovative conservation efforts. Together, this work presents an unprecedented system that conservation can leverage to enrich the recovery program of an endangered species
Factorization in the model of unstable particles with continuous masses
We study processes with unstable particles in intermediate time-like states.
It is shown that the amplitudes squared of such processes factor exactly in the
framework of the model of unstable particles with continuous masses. Decay
widths and cross sections can then be represented in a universal factorized
form for an arbitrary set of interacting particles. This exact factorization is
caused by specific structure of propagators in the model. We formulate the
factorization method and perform a phenomenological analysis of the
factorization effects. The factorization method considerably simplifies
calculations while leading to compact and reasonable results.Comment: 20 pages, 6 figure
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