255 research outputs found
Fundamentals and applications of spatial dissipative solitons in photonic devices : [Chapter 6]
We review the properties of optical spatial dissipative solitons (SDS). These are stable, self‐localized optical excitations sitting on a uniform, or quasi‐uniform, background in a dissipative environment like a nonlinear optical cavity. Indeed, in optics they are often termed “cavity solitons.” We discuss their dynamics and interactions in both ideal and imperfect systems, making comparison with experiments. SDS in lasers offer important advantages for applications. We review candidate schemes and the tremendous recent progress in semiconductor‐based cavity soliton lasers. We examine SDS in periodic structures, and we show how SDS can be quantitatively related to the locking of fronts. We conclude with an assessment of potential applications of SDS in photonics, arguing that best use of their particular features is made by exploiting their mobility, for example in all‐optical delay lines
Bibliography of Lewis Research Center technical publications announced in 1992
This compilation of abstracts describes and indexes the technical reporting that resulted from the scientific and engineering work performed and managed by the Lewis Research Center in 1992. All the publications were announced in the 1992 issues of STAR (Scientific and Technical Aerospace Reports) and/or IAA (International Aerospace Abstracts). Included are research reports, journal articles, conference presentations, patents and patent applications, and theses
The physics and applications of strongly coupled plasmas levitated in electrodynamic traps
Charged (nano)particles confined in electrodynamic traps can evolve into
strongly correlated Coulomb systems, which are the subject of current
investigation. Exciting physical phenomena associated to Coulomb systems have
been reported such as autowave generation, phase transitions, system
self-locking at the ends of the linear Paul trap, self-organization in layers,
or pattern formation and scaling. The dynamics of ordered structures consisting
of highly nonideal similarly charged nanoparticles, with coupling parameter of
the order is investigated. This approach enables us to study
the interaction of nanoparticle structures in presence and in absence of the
neutralizing plasma background, as well as to investigate various types of
phenomena and physical forces these structures experience. Applications of
electrodynamic levitation for mass spectrometry, including containment and
study of single aerosols and nanoparticles are reviewed, with an emphasis on
state of the art experiments and techniques, as well as future trends. Late
experimental data suggest that inelastic scattering can be successfully applied
to the detection of biological particles such as pollen, bacteria, aerosols,
traces of explosives or synthetic polymers. Brownian dynamics is used to
characterize charged particle evolution in time and thus identify regions of
stable trapping. An analytical model is used to explain the experimental
results. Numerical simulations take into account the stochastic forces of
random collisions with neutral particles, the viscosity of the gas medium, the
regular forces produced by the a.c. trapping voltage, and the gravitational
force. We show that microparticle dynamics is characterized by a stochastic
Langevin differential equation. Laser plasma acceleration of charged particles
is also discussed
Articles indexats publicats per investigadors del Campus de Terrassa: 2013
Aquest informe recull els 228 treballs publicats per 177 investigadors/es del Campus de Terrassa en revistes indexades al Journal Citation Report durant el 2013Preprin
Numerical Simulations
This book will interest researchers, scientists, engineers and graduate students in many disciplines, who make use of mathematical modeling and computer simulation. Although it represents only a small sample of the research activity on numerical simulations, the book will certainly serve as a valuable tool for researchers interested in getting involved in this multidisciplinary field. It will be useful to encourage further experimental and theoretical researches in the above mentioned areas of numerical simulation
Nonlinear Dynamics
This volume covers a diverse collection of topics dealing with some of the fundamental concepts and applications embodied in the study of nonlinear dynamics. Each of the 15 chapters contained in this compendium generally fit into one of five topical areas: physics applications, nonlinear oscillators, electrical and mechanical systems, biological and behavioral applications or random processes. The authors of these chapters have contributed a stimulating cross section of new results, which provide a fertile spectrum of ideas that will inspire both seasoned researches and students
Dynamics of biologically informed neural mass models of the brain
This book contributes to the development and analysis of computational models that help brain function to be understood. The mean activity of a brain area is mathematically modeled in such a way as to strike a balance between tractability and biological plausibility. Neural mass models (NMM) are used to describe switching between qualitatively different regimes (such as those due to pharmacological interventions, epilepsy, sleep, or context-induced state changes), and to explain resonance phenomena in a photic driving experiment. The description of varying states in an ordered sequence gives a principle scheme for the modeling of complex phenomena on multiple time scales. The NMM is matched to the photic driving experiment routinely applied in the diagnosis of such diseases as epilepsy, migraine, schizophrenia and depression. The model reproduces the clinically relevant entrainment effect and predictions are made for improving the experimental setting.Die vorliegende Arbeit stellt einen Beitrag zur Entwicklung und Analyse von
Computermodellen zum Verständnis von Hirnfunktionen dar. Es wird die
mittlere Aktivität eines Hirnareals analytisch einfach und dabei
biologisch plausibel modelliert. Auf Grundlage eines Neuronalen
Massenmodells (NMM) werden die Wechsel zwischen Oszillationsregimen (z.B.
durch pharmakologisch, epilepsie-, schlaf- oder kontextbedingte
Zustandsänderungen) als geordnete Folge beschrieben und Resonanzphänomene
in einem Photic-Driving-Experiment erklärt. Dieses NMM kann sehr komplexe
Dynamiken (z.B. Chaos) innerhalb biologisch plausibler Parameterbereiche
hervorbringen. Um das Verhalten abzuschätzen, wird das NMM als Funktion
konstanter Eingangsgrößen und charakteristischer Zeitenkonstanten
vollständig auf Bifurkationen untersucht und klassifiziert. Dies
ermöglicht die Beschreibung wechselnder Regime als geordnete Folge durch
spezifische Eingangstrajektorien. Es wird ein Prinzip vorgestellt, um
komplexe Phänomene durch Prozesse verschiedener Zeitskalen darzustellen.
Da aufgrund rhythmischer Stimuli und der intrinsischen Rhythmen von
Neuronenverbänden die Eingangsgrößen häufig periodisch sind, wird das
Verhalten des NMM als Funktion der Intensität und Frequenz einer
periodischen Stimulation mittels der zugehörigen Lyapunov-Spektren und der
Zeitreihen charakterisiert. Auf der Basis der größten Lyapunov-Exponenten
wird das NMM mit dem Photic-Driving-Experiment überein gebracht. Dieses
Experiment findet routinemäßige Anwendung in der Diagnostik verschiedener
Erkrankungen wie Epilepsie, Migräne, Schizophrenie und Depression. Durch
die Anwendung des vorgestellten NMM wird der für die Diagnostik
entscheidende Mitnahmeeffekt reproduziert und es werden Vorhersagen für
eine Verbesserung der Indikation getroffen
- …