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Dynamical Behaviour (dynamical + behaviour)
Selected AbstractsNumerical Analysis and Simulation Analysis for Space-Time DataCONTRIBUTIONS TO PLASMA PHYSICS, Issue 10 2006M. A. Hassouba Abstract Spatio temporal dynamics of the positive column of a dc neon glow discharge is studied and investigated experimentally and theoretically. Spatio temporal analysis by means of biorthogonal decomposition method (BOD) gives insights into the mechanism of irregularity and can be employed for characterization of spatio- temporal complexity. In the weak nonlinear region, the wave dynamics is approximated by an amplitude equation of the Ginzburg-Landau equation (CGLE) with complex coefficients and an additional integral term based on a fluid model. In the present work we deal with irregular spatio-temporal data. A comparison between the numerical analysis of the experimental data and simulation results are studied. A good agreement between the dynamical behaviour for experimental space-time data and theoretical simulation space-time results was obtained. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Large displacement behaviour of a structural model with foundation uplift under impulsive and earthquake excitationsEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 3 2003Giuseppe Oliveto Abstract This paper considers the dynamical behaviour of a structural model with foundation uplift. The equations of motion of the system considered are derived for large displacements thus allowing for the eventual overturning of the system. The transition conditions between successive phases of motion, derived in terms of the specific Lagrangian co-ordinates used in the formulation of the equations of motion, present innovative aspects which resolve some previously inexplicable behaviour in the structural response reported in the literature. The dynamical behaviour of the model is considered under impulsive and long-duration ground motions. The minimum horizontal acceleration impulses for the uplift and the overturning of the system are evaluated in analytical form. The sensitivity of the model to uplifting and to overturning under impulsive excitations is established as a function of few significant structural parameters. Numerical applications have been performed changing either the structural parameters or the loading parameter, in order to analyse several dynamical behaviours and also to validate the analytical results. For earthquake ground motions the results, reported in the form of response spectra, show that linearized models generally underestimate, sometimes significantly, the structural response. Copyright © 2003 John Wiley & Sons, Ltd. [source] Classical predator,prey system with infection of prey population,a mathematical modelMATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 14 2003J. Chattopadhyay Abstract The present paper deals with the problem of a classical predator,prey system with infection of prey population. A classical predator,prey system is split into three groups, namely susceptible prey, infected prey and predator. The relative removal rate of the susceptible prey due to infection is worked out. We observe the dynamical behaviour of this system around each of the equilibria and point out the exchange of stability. It is shown that local asymptotic stability of the system around the positive interior equilibrium ensures its global asymptotic stability. We prove that there is always a Hopf bifurcation for increasing transmission rate. To substantiate the analytical findings, numerical experiments have been carried out for hypothetical set of parameter values. Our analysis shows that there is a threshold level of infection below which all the three species will persist and above which the disease will be epidemic. Copyright © 2003 John Wiley & Sons, Ltd. [source] Partial pole assignment for the vibrating system with aerodynamic effectNUMERICAL LINEAR ALGEBRA WITH APPLICATIONS, Issue 1 2004Wen-Wei Lin Abstract The partial pole assignment (PPA) problem is the one of reassigning a few unwanted eigenvalues of a control system by feedback to suitably chosen ones, while keeping the remaining large number of eigenvalues unchanged. The problem naturally arises in modifying dynamical behaviour of the system. The PPA has been considered by several authors in the past for standard state,space systems and for quadratic matrix polynomials associated with second-order systems. In this paper, we consider the PPA for a cubic matrix polynomial arising from modelling of a vibrating system with aerodynamics effects and derive explicit formulas for feedback matrices in terms of the coefficient matrices of the polynomial. Our results generalize those of a quadratic matrix polynomial by Datta et al. (Linear Algebra Appl. 1997;257: 29) and is based on some new orthogonality relations for eigenvectors of the cubic matrix polynomial, which also generalize the similar ones reported in Datta et al. (Linear Algebra Appl. 1997;257: 29) for the symmetric definite quadratic pencil. Besides playing an important role in our solution for the PPA, these orthogonality relations are of independent interests, and believed to be an important contribution to linear algebra in its own right. Copyright © 2003 John Wiley & Sons, Ltd. [source] Influence of a constant electric field in cavities of nanotubes.PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 6 2008Bloch oscillations, electron confinement Abstract We investigate numerically the dynamical properties of electrons in cavities of nanotubes under the influence of an external electric field. In particular, the dynamical behaviour of electrons is studied when the nanostructure is connected to two electrodes at different electric potential. Here it is shown how the phenomenon of Bloch oscillations is produced. Besides this, we study the evolution of electrons when the electric field is placed along different regions of the nanotube, showing that the electron is confined at its initial region instead of spread along the whole structure. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Experimental investigation of a moored floating systemPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2008Daniel Beyer Floating structures are generally excited by a more or less irregular sea state. Therefore the structure undergoes a nonlinear dynamical behaviour which results from hydrodynamic effects or the kinematic coupling of different components. The motions of these structures have been analysed intensively with numerical techniques which predict a wide range of nonlinear effects. On the other hand, experiments are still important when it comes to verifying these theoretical findings. Investigating such a floating structure experimentally requires a complex setup: A wave generator needs to be driven in an appropriate way to yield waves with the required characteristics at the structure. The structure itself is usually designed similar to a real,world system and it has to allow for a comparison with numerical analyses. Sensors which measure the tracks of the individual components not only have to reach a prescribed precision but also need to ensure that the motion is not perturbed as a result of the measurements. Lastly, unwanted disturbances have to be avoided. For experiments in a wave tank this includes that reflections have to be minimized. This talk addresses the development of an experimental setup for the investigation of a floating structure. It highlights components which are found to be critical for the obtained accuracy and proposes techniques to reduce experimental errors. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Single-crystal diffuse scattering studies on polymorphs of molecular crystals.ACTA CRYSTALLOGRAPHICA SECTION B, Issue 3 2009The drug benzocaine (ethyl 4-aminobenzoate), commonly used as a local anaesthetic, is a bimorphic solid at room temperature. Form (I) is monoclinic P21/c, while the metastable form (II) is orthorhombic P212121. Three-dimensional diffuse X-ray scattering data have been collected for the two forms on the 11-ID-B beamline at the Advanced Photon Source (APS). Both forms show strong and highly structured diffuse scattering. The data have been interpreted and analysed using Monte Carlo (MC) modelling on the basis that the scattering is purely thermal in origin and indicates the presence of highly correlated molecular motions. In both forms (I) and (II) broad diffuse streaks are observed in the 0kl section which indicate strong longitudinal displacement correlations between molecules in the ,031, directions, extending over distances of up to 50,Å. Streaks extending between Bragg peaks in the hk0 section normal to [100] correspond to correlated motions of chains of molecules extending along a that are linked by N,H...O=C hydrogen bonds and which occur together as coplanar ribbon pairs. The main difference between the two forms is in the dynamical behaviour of the ribbon pairs and in particular how they are able to slide relative to each other. While for form (I) a model involving harmonic springs is able to describe the motion satisfactorily, as simple excursions away from the average structure, there is evidence in form (II) of anharmonic effects that are precursors of a phase transition to a new low-temperature phase, form (III), that was subsequently found. [source] Temperature-dependent macromolecular X-ray crystallographyACTA CRYSTALLOGRAPHICA SECTION D, Issue 4 2010Martin Weik X-ray crystallography provides structural details of biological macromolecules. Whereas routine data are collected close to 100,K in order to mitigate radiation damage, more exotic temperature-controlled experiments in a broader temperature range from 15,K to room temperature can provide both dynamical and structural insights. Here, the dynamical behaviour of crystalline macromolecules and their surrounding solvent as a function of cryo-temperature is reviewed. Experimental strategies of kinetic crystallography are discussed that have allowed the generation and trapping of macromolecular intermediate states by combining reaction initiation in the crystalline state with appropriate temperature profiles. A particular focus is on recruiting X-ray-induced changes for reaction initiation, thus unveiling useful aspects of radiation damage, which otherwise has to be minimized in macromolecular crystallography. [source] A planetary system with an escaping MarsASTRONOMISCHE NACHRICHTEN, Issue 1 2007Á. Süli Abstract The chaotic behaviour of the motion of the planets in our Solar System is well established. In this work to model a hypothetical extrasolar planetary system our Solar System was modified in such a way that we replaced the Earth by a more massive planet and let the other planets and all the orbital elements unchanged. The major result of former numerical experiments with a modified Solar System was the appearance of a chaotic window at ,E , (4, 6), where the dynamical state of the system was highly chaotic and even the body with the smallest mass escaped in some cases. On the contrary for very large values of the mass of the Earth, even greater than that of Jupiter regular dynamical behaviour was observed. In this paper the investigations are extended to the complete Solar System and showed, that this chaotic window does still exist. Tests in different ,Solar Systems' clarified that including only Jupiter and Saturn with their actual masses together with a more ,massive' Earth (4 < ,E < 6) perturbs the orbit of Mars so that it can even be ejected from the system. Using the results of the Laplace-Lagrange secular theory we found secular resonances acting between the motions of the nodes of Mars, Jupiter and Saturn. These secular resonances give rise to strong chaos, which is the cause of the appearance of the instability window. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Large displacement behaviour of a structural model with foundation uplift under impulsive and earthquake excitationsEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 3 2003Giuseppe Oliveto Abstract This paper considers the dynamical behaviour of a structural model with foundation uplift. The equations of motion of the system considered are derived for large displacements thus allowing for the eventual overturning of the system. The transition conditions between successive phases of motion, derived in terms of the specific Lagrangian co-ordinates used in the formulation of the equations of motion, present innovative aspects which resolve some previously inexplicable behaviour in the structural response reported in the literature. The dynamical behaviour of the model is considered under impulsive and long-duration ground motions. The minimum horizontal acceleration impulses for the uplift and the overturning of the system are evaluated in analytical form. The sensitivity of the model to uplifting and to overturning under impulsive excitations is established as a function of few significant structural parameters. Numerical applications have been performed changing either the structural parameters or the loading parameter, in order to analyse several dynamical behaviours and also to validate the analytical results. For earthquake ground motions the results, reported in the form of response spectra, show that linearized models generally underestimate, sometimes significantly, the structural response. Copyright © 2003 John Wiley & Sons, Ltd. [source] | |||||||||||||||||||