1,390 research outputs found
Magnetic Cellular Nonlinear Network with Spin Wave Bus for Image Processing
We describe and analyze a cellular nonlinear network based on magnetic
nanostructures for image processing. The network consists of magneto-electric
cells integrated onto a common ferromagnetic film - spin wave bus. The
magneto-electric cell is an artificial two-phase multiferroic structure
comprising piezoelectric and ferromagnetic materials. A bit of information is
assigned to the cell's magnetic polarization, which can be controlled by the
applied voltage. The information exchange among the cells is via the spin waves
propagating in the spin wave bus. Each cell changes its state as a combined
effect of two: the magneto-electric coupling and the interaction with the spin
waves. The distinct feature of the network with spin wave bus is the ability to
control the inter-cell communication by an external global parameter - magnetic
field. The latter makes possible to realize different image processing
functions on the same template without rewiring or reconfiguration. We present
the results of numerical simulations illustrating image filtering, erosion,
dilation, horizontal and vertical line detection, inversion and edge detection
accomplished on one template by the proper choice of the strength and direction
of the external magnetic field. We also present numerical assets on the major
network parameters such as cell density, power dissipation and functional
throughput, and compare them with the parameters projected for other
nano-architectures such as CMOL-CrossNet, Quantum Dot Cellular Automata, and
Quantum Dot Image Processor. Potentially, the utilization of spin waves
phenomena at the nanometer scale may provide a route to low-power consuming and
functional logic circuits for special task data processing
CNN model for studying dynamics and travelling wave solutions of FitzHugh-Nagumo equation
AbstractIn this paper, a cellular neural network (CNN) model of FitzHugh–Nagumo equation is introduced. Dynamical behavior of this model is investigated using harmonic balance method. For the CNN model of FitzHugh–Nagumo equation, propagation of solitary waves have been proved
Discrete Wave Propagation In Quadratically Nonlinear Media
Discrete models are used in describing various microscopic phenomena in many branches of science, ranging from biology through chemistry to physics. Arrays of evanescently coupled, equally spaced, identical waveguides are prime examples of optical structures in which discrete dynamics can be easily observed and investigated. As a result of discretization, these structures exhibit unique diffraction properties with no analogy in continuous systems. Recently nonlinear discrete optics has attracted a growing interest, triggered by the observation of discrete solitons in AlGaAs waveguide arrays reported by Eisenberg et al. in 1998. So far, the following experiments involved systems with third order nonlinearities. In this work, an experimental investigation of discrete nonlinear wave propagation in a second order nonlinear medium is presented. This system deserves particular attention because the nonlinear process involves two or three components at different frequencies mutually locked by a quadratic nonlinearity, and new degrees of freedom enter the dynamical process. In the first part of dissertation, observation of the discrete Talbot effect is reported. In contrast to continuous systems, where Talbot self-imaging effect occurs irrespective of the pattern period, in discrete configurations this process is only possible for a specific set of periodicities. The major part of the dissertation is devoted to the investigation of soliton formation in lithium niobate waveguide arrays with a tunable cascaded quadratic nonlinearity. Soliton species with different topology (unstaggered all channels in-phase, and staggered neighboring channels with a pi relative phase difference) are identified in the same array. The stability of the discrete solitons and plane waves (modulational instability) are experimentally investigated. In the last part of the dissertation, a phase-insensitive, ultrafast, all-optical spatial switching and frequency conversion device based on quadratic waveguide array is demonstrated. Spatial routing and wavelength conversion of milliwatt signals is achieved without pulse distortions
Interacting bosons in two-dimensional lattices with localized dissipation
Motivated by the recent experiment [Takafumi Tomita \emph{et al.}, Sci. Adv.
{\bf 3}, (2017)], we study the dynamics of interacting bosons in a
two-dimensional optical lattice with local dissipation. Together with the
Gutzwiller mean-field theory for density matrices and Lindblad master equation,
we show how the onsite interaction between bosons affects the particle loss for
various strengths of dissipation. For moderate dissipation, the trend in
particle loss differs significantly near the superfluid-Mott boundary than the
deep superfluid regime. While the loss is suppressed for stronger dissipation
in the deep superfluid regime, revealing the typical quantum Zeno effect, the
loss near the phase boundary shows non-monotonic dependence on the dissipation
strength. We furthermore show that close to the phase boundary, the long-time
dynamics is well contrasted with the dissipative dynamics deep into the
superfluid regime. Thus the loss of particle due to dissipation may act as a
probe to differentiate strongly-correlated superfluid regime from its
weakly-correlated counterpart.Comment: 7 pages, 5 figure
Characterization of Photoacoustic Flow Cytometry Signals
Photoacoustic flow cytometry has been utilized to clinically determine the presence of melanoma circulating tumor cells (CTCs). Further investigation was conducted into the morphology of detection signals and how they could be manipulated to allow for further classification. Novel features were extracted from waveforms that appear to have strong classification ability. Neural networks were also used to determine classification potential and the creation of feature mapping for future unsupervised classification. Detections were expanded from single waves to a time dependent multiwave event. Waveforms were also determined to be of non-parametric distribution, allowing for classification by neural network but not allowing for reduction into feature maps with techniques used in the study
Harnessing collective radiative phenomena on a photonic kagome lattice
Photonic lattices enable experimental exploration of transport and
localization phenomena, two of the mayor goals in physics and technology. In
particular, the optical excitation of some lattice sites which evanescently
couple to a lattice array emulates radiation processes into structured
reservoirs, a fundamental subject in quantum optics. Moreover, the simultaneous
excitation of two sites simulates collective phenomena, leading to
phase-controlled enhanced or suppressed radiation, namely super and
subradiance. This work presents an experimental study of collective radiative
processes on a photonic kagome lattice. A single or simultaneous -- in or
out-of-phase -- excitation of the outlying sites controls the radiation
dynamics. Specifically, we demonstrate a controlable transition between a fully
localized profile at the two outlying sites and a completely dispersed state
into the quasi-continuum. Our result presents photonic lattices as a platform
to emulate and experimentally explore quantum optical phenomena in
two-dimensional structured reservoirs, while harnessing such phenomena for
controlling transport dynamics and implementing all-optical switching devices.Comment: 7 pages, 4 figure
Dynamics and manipulation of entanglement in coupled harmonic systems with many degrees of freedom
Published versio
Human Body Scattering Effects at Millimeter Waves Frequencies for Future 5G Systems and Beyond
[ES] Se espera que las futuras comunicaciones móviles experimenten una revolución técnica que vaya más allá de las velocidades de datos de Gbps y reduzca las latencias de las velocidades de datos a niveles muy cercanos al milisegundo. Se han investigado nuevas tecnologÃas habilitadoras para lograr estas exigentes especificaciones. Y la utilización de las bandas de ondas milimétricas, donde hay mucho espectro disponible, es una de ellas.
Debido a las numerosas dificultades técnicas asociadas a la utilización de esta banda de frecuencias, se necesitan complicados modelos de canal para anticipar las caracterÃsticas del canal de radio y evaluar con precisión el rendimiento de los sistemas celulares en milimétricas. En concreto, los modelos de propagación más precisos son los basados en técnicas de trazado de rayos deterministas. Pero estas técnicas tienen el estigma de ser computacionalmente exigentes, y esto dificulta su uso para caracterizar el canal de radio en escenarios interiores complejos y dinámicos. La complejidad de la caracterización de estos escenarios depende en gran medida de la interacción del cuerpo humano con el entorno radioeléctrico, que en las ondas milimétricas suele ser destructiva y muy impredecible.
Por otro lado, en los últimos años, la industria de los videojuegos ha desarrollado potentes herramientas para entornos hiperrealistas, donde la mayor parte de los avances en esta emulación de la realidad tienen que ver con el manejo de la luz. AsÃ, los motores gráficos de estas plataformas se han vuelto cada vez más eficientes para manejar grandes volúmenes de información, por lo que son ideales para emular el comportamiento de la propagación de las ondas de radio, asà como para reconstruir un escenario interior complejo. Por ello, en esta Tesis se ha aprovechado la capacidad computacional de este tipo de herramientas para evaluar el canal radioeléctrico milimétricas de la forma más eficiente posible.
Esta Tesis ofrece unas pautas para optimizar la propagación de la señal en milimétricas en un entorno interior dinámico y complejo, para lo cual se proponen tres objetivos principales.
El primer objetivo es evaluar los efectos de dispersión del cuerpo humano cuando interactúa con el canal de propagación. Una vez evaluado, se propuso un modelo matemático y geométrico simplificado para calcular este efecto de forma fiable y rápida. Otro objetivo fue el diseño de un reflector pasivo modular en milimétricas, que optimiza la cobertura en entornos de interior, evitando la interferencia del ser humano en la propagación. Y, por último, se diseñó un sistema de apuntamiento del haz predictivo en tiempo real, para que opere con el sistema de radiación en milimétricas, cuyo objetivo es evitar las pérdidas de propagación causadas por el cuerpo humano en entornos interiores dinámicos y complejos.[CA] S'espera que les futures comunicacions mòbils experimenten una revolució tècnica que vaja més enllà de les velocitats de dades de Gbps i reduïsca les latències de les velocitats de dades a nivells molt pròxims al milisegundo. S'han investigat noves tecnologies habilitadoras per a aconseguir estes exigents especificacions. I la utilització de les bandes d'ones millimètriques, on hi ha molt espectre disponible, és una d'elles.
A causa de les nombroses dificultats tècniques associades a la utilització d'esta banda de freqüències, es necessiten complicats models de canal per a anticipar les caracterÃstiques del canal de rà dio i avaluar amb precisió el rendiment dels sistemes cellulars en millimètriques. En concret, els models de propagació més precisos són els basats en tècniques de traçat de rajos deterministes. Però estes tècniques tenen l'estigma de ser computacionalment exigents, i açò dificulta el seu ús per a caracteritzar el canal de rà dio en escenaris interiors complexos i dinà mics. La complexitat de la caracterització d'estos escenaris depén en gran manera de la interacció del cos humà amb l'entorn radioelèctric, que en les ones millimètriques sol ser destructiva i molt impredicible.
D'altra banda, en els últims anys, la indústria dels videojocs ha desenrotllat potents ferramentes per a entorns hiperrealistes, on la major part dels avanços en esta emulació de la realitat tenen a veure amb el maneig de la llum. AixÃ, els motors grà fics d'estes plataformes s'han tornat cada vegada més eficients per a manejar grans volums d'informació, per la qual cosa són ideals per a emular el comportament de la propagació de les ones de rà dio, aixà com per a reconstruir un escenari interior complex. Per això, en esta Tesi s'ha aprofitat la capacitat computacional d'este tipus de ferramentes per a avaluar el canal radioelèctric millimètriques de la manera més eficient possible.
Esta Tesi oferix unes pautes per a optimitzar la propagació del senyal en millimètriques en un entorn interior dinà mic i complex, per a la qual cosa es proposen tres objectius principals. El primer objectiu és avaluar els efectes de dispersió del cos humà quan interactua amb el canal de propagació. Una vegada avaluat, es va proposar un model matemà tic i geomètric simplificat per a calcular este efecte de forma fiable i rà pida. Un altre objectiu va ser el disseny d'un reflector passiu modular en millimètriques, que optimitza la cobertura en entorns d'interior, evitant la interferència del ser humà en la propagació, per a aixà evitar pèrdues de propagació addicionals. I, finalment, es va dissenyar un sistema d'apuntament del feix predictiu en temps real, perquè opere amb el sistema de radiació en millimètriques, l'objectiu del qual és evitar les pèrdues de propagació causades pel cos humà en entorns interiors dinà mics i complexos.[EN] Future mobile communications are expected to experience a technical revolution that goes beyond Gbps data rates and reduces data rate latencies to levels very close to a millisecond. New enabling technologies have been researched to achieve these demanding specifications. The utilization of mmWave bands, where a lot of spectrum is available, is one of them.
Due to the numerous technical difficulties associated with using this frequency band, complicated channel models are necessary to anticipate the radio channel characteristics and to accurately evaluate the performance of cellular systems in mmWave. In particular, the most accurate propagation models are those based on deterministic ray tracing techniques. But these techniques have the stigma of being computationally intensive, and this makes it difficult to use them to characterize the radio channel in complex and dynamic indoor scenarios. The complexity of characterizing these scenarios depends largely on the interaction of the human body with the radio environment, which at mmWaves is often destructive and highly unpredictable.
On the other hand, in recent years, the video game industry has developed powerful tools for hyper-realistic environments, where most of the progress in this reality emulation has to do with the handling of light. Therefore, the graphic engines of these platforms have become more and more efficient to handle large volumes of information, becoming ideal to emulate the radio wave propagation behavior, as well as to reconstruct a complex interior scenario. Therefore, in this Thesis one has taken advantage of the computational capacity of this type of tools to evaluate the mmWave radio channel in the most efficient way possible. This Thesis offers some guidelines to optimize the signal propagation in mmWaves in a dynamic and complex indoor environment, for which three main objectives are proposed.
The first objective has been to evaluate the scattering effects of the human body when it interacts with the propagation channel. Once evaluated, a simplified mathematical and geometrical model has been proposed to calculate this effect in a reliable and fast way. Another objective has been the design of a modular passive reflector in mmWaves, which optimizes the coverage in indoor environments, avoiding human interference in the propagation, in order to avoid its harmful scattering effects. And finally, a real-time predictive beam steering system has been designed for the mmWaves radiation system, in order to avoid propagation losses caused by the human body in dynamic and complex indoor environments.Romero Peña, JS. (2022). Human Body Scattering Effects at Millimeter Waves Frequencies for Future 5G Systems and Beyond [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/19132
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