Scaling properties of a ferromagnetic thin film model at the depinning transition

In this paper, we perform a detailed study of the scaling properties of a ferromagnetic thin film model. Recently, interest has increased in the scaling properties of the magnetic domain wall (MDW) motion in disordered media when an external driving field is present. We consider a (1+1)-dimensional model, based on evolution rules, able to describe the MDW avalanches. The global interface width of this model shows Family-Vicsek scaling with roughness exponent $\zeta\simeq 1.585$ and growth exponent $\beta\simeq 0.975$. In contrast, this model shows scaling anomalies in the interface local properties characteristic of other systems with depinning transition of the MDW, e.g. quenched Edwards-Wilkinson (QEW) equation and random-field Ising model (RFIM) with driving. We show that, at the depinning transition, the saturated average velocity $v_\mathrm{sat}\sim f^\theta$ vanished very slowly (with $\theta\simeq 0.037$) when the reduced force $f=p/p_\mathrm{c}-1\to 0^{+}$. The simulation results show that this model verifies all accepted scaling relations which relate the global exponents and the correlation length (or time) exponents, valid in systems with depinning transition. Using the interface tilting method, we show that the model, close to the depinning transition, exhibits a nonlinearity similar to the one included in the Kardar-Parisi-Zhang (KPZ) equation. The nonlinear coefficient $\lambda\sim f^{-\phi}$ with $\phi\simeq -1.118$, which implies that $\lambda\to 0$ as the depinning transition is approached, a similar qualitatively behaviour to the driven RFIM. We conclude this work by discussing the main features of the model and the prospects opened by it.Comment: 10 pages, 5 figures, 1 tabl

Fluctuations of a surface relaxation model in interacting scale free networks

Isolated complex networks have been studied deeply in the last decades due to the fact that many real systems can be modeled using these types of structures. However, it is well known that the behavior of a system not only depends on itself, but usually also depends on the dynamics of other structures. For this reason, interacting complex networks and the processes developed on them have been the focus of study of many researches in the last years. One of the most studied subjects in this type of structures is the Synchronization problem, which is important in a wide variety of processes in real systems. In this manuscript we study the synchronization of two interacting scale-free networks, in which each node has $ke$ dependency links with different nodes in the other network. We map the synchronization problem with an interface growth, by studying the fluctuations in the steady state of a scalar field defined in both networks. We find that as $ke$ slightly increases from $ke=0$, there is a really significant decreasing in the fluctuations of the system. However, this considerable improvement takes place mainly for small values of $ke$, when the interaction between networks becomes stronger there is only a slight change in the fluctuations. We characterize how the dispersion of the scalar field depends on the internal degree, and we show that a combination between the decreasing of this dispersion and the integer nature of our growth model are the responsible for the behavior of the fluctuations with $ke$.Comment: 11 pages, 4 figures and 1 tabl

Satisfaction-Aware Data Offloading in Surveillance Systems

In this thesis, exploiting Fully Autonomous Aerial Systems\u27 (FAAS) and Mobile Edge Computing (MEC) servers\u27 computing capabilities to introduce a novel data offloading framework to support the energy and time-efficient video processing in surveillance systems based on satisfaction games. A surveillance system is introduced consisting of Areas of Interest (AoIs), where a MEC server is associated with each AoI, and a FAAS is flying above the AoIs to support the IP cameras\u27 computing demands. Each IP camera adopts a utility function capturing its Quality of Service (QoS) considering the experienced time and energy overhead to offload and process remotely or locally the data. A non-cooperative game among the cameras is formulated to determine the amount of offloading data to the MEC server and/or the FAAS, and the novel concept of Satisfaction Equilibrium (SE) is introduced where the IP cameras satisfy their minimum QoS prerequisites instead of maximizing their performance by consuming additional system resources. A distributed learning algorithm determines the IP cameras\u27 stable data offloading. Also, a reinforcement learning algorithm indicates the FAAS\u27s movement among the AoIs exploiting the accuracy, timeliness, and certainty of the collected data by the IP cameras per AoI. Detailed numerical and comparative results are presented to show the operation and efficiency of the proposed framework

Displasia broncopulmonar: Incidencia y factores de riesgo en recién nacidos pretérmino de muy bajo peso. INMP-2009

El documento digital no refiere asesorPublicación a texto completo no autorizada por el autorDetermina la incidencia y factores de riesgo para displasia broncopulmonar (DBP) en recién nacidos (RN) pretérmino de muy bajo peso al nacer del Instituto Nacional Materno Perinatal en el 2009. El estudio es retrospectivo, observacional, de corte longitudinal y analítico (estudio de casos y controles). Se estudió a todos los RN pretérnino de muy bajo peso al nacer a los cuales se les dividió en 2 grupos; Grupo 1 (casos), formado por los RN pretérnino de muy bajo peso al nacer con diagnóstico de DBP. Grupo 2 (control), formado por los RN pretérnino de muy bajo peso al nacer sin DBP. En ambos grupos se buscó la exposición a factores de riesgo prenatales, natales y postnatales. Se elaboró tablas de contingencia para buscar diferencias entre ambos grupos mediante el test de Chi cuadrado con un nivel de significancia de p ≤ 0,05. Posteriormente de calculó el Odds ratio y se efectuó regresión logística. Se estudiaron a 106 RN pretérmino de muy bajo peso al nacer. La DBP estuvo presente en 36 (34%), esta fue más frecuente a menor edad gestacional y menor peso de nacimiento. Los factores de riesgo encontrados fueron: 1) Edad gestacional menor a 28 semanas con OR de 7,7 (IC al 95% 1,2 – 25), 2) Peso de nacimiento menor a 1000 gramos con OR de 4,8 (IC al 95% de: 1,2 – 22), 3) Ventilación mecánica asistida con un OR de 40 (IC al 95% de 6,6 – 140) y 4) Persistencia del conducto arterioso con un OR de 4,6 )IC al 95% de 1,2 – 17,7). Se concluye que la incidencia de DBP en el INMP en el 2009 fue alta y la edad gestacional, peso de nacimiento, la ventilación mecánica y el persistencia del ductus arteriso fueron factores asociados.Trabajo académic

Switched Reluctance Drives with Degraded Mode for Electric Vehicles

There are many types of electrical machines suitable for electric vehicles. Nowadays, most manufacturers and researchers tend towards two major alternatives: permanent magnet synchronous machines and induction machines. However, these are not the only competitive candidates. Reluctance machines, which have been well-known for some decades already, present some interesting advantages. For instance, switched reluctance machines are intrinsically redundant and fault-tolerant, which makes them attractive for applications in which robustness is compulsory. In this sense, switched reluctance drives can keep working even when one of their phases loses its functionality for any reason. In an electric vehicle, this would mean being able to keep driving the vehicle even after some failures, although with reduced performance (in degraded mode). In this chapter, switched reluctance drives for traction applications are analyzed, focusing on their capability to operate in degraded mode (with m-1 phases available)

Design Parameter Analysis of Point Absorber WEC via an Evolutionary-Algorithm-Based Dimensioning Tool

Wave energy conversion has an essential difference from other renewable energies since the dependence between the devices design and the energy resource is stronger. Dimensioning is therefore considered a key stage when a design project of Wave Energy Converters (WEC) is undertaken. Location, WEC concept, Power Take-Off (PTO) type, control strategy and hydrodynamic resonance considerations are some of the critical aspects to take into account to achieve a good performance. The paper proposes an automatic dimensioning methodology to be accomplished at the initial design project stages and the following elements are described to carry out the study: an optimization design algorithm, its objective functions and restrictions, a PTO model, as well as a procedure to evaluate the WEC energy production. After that, a parametric analysis is included considering different combinations of the key parameters previously introduced. A variety of study cases are analysed from the point of view of energy production for different design-parameters and all of them are compared with a reference case. Finally, a discussion is presented based on the results obtained, and some recommendations to face the WEC design stage are given

Envelhecimento acelerado em sementes de melão

Accelerated aging is one of the most useful tests used for the evaluation of seed vigor but it is seldomly used to test melon (Cucumis melo L.) seeds. The objective this research was to compare different procedures of the accelerated aging test to evaluate the physiological quality of melon seeds and the efficiency of using saturated salt solution for the control of water uptake by seeds. Five seed lots each of the hybrids AF-646 and AF-682 were tested for germination, seedling emergence, traditional accelerated aging (periods 0f 48, 72 and 96 hours, at 38 or 41°C) and salt saturated accelerated aging. The accelerated aging test (traditional procedure and with salt solution) for 72h and 96h, at 38 or 41°C was sensitive to detect differences in the physiological quality of the seeds. It was also observed that the seed water content after salt saturated accelerated aging was lower and more uniform, thus presenting advantagens in relation to the traditional procedure.O teste de envelhecimento acelerado é um dos mais utilizados para a avaliação do potencial fisiológico das sementes de várias espécies. Entretanto, estudos com sementes de melão ainda são escassos. Avaliou-se procedimentos para a condução do teste de envelhecimento acelerado para avaliação do potencial fisiológico de sementes de melão (Cucumis melo L.), incluindo o uso de solução saturada de sal em substituição à água. Cinco lotes de sementes, dos híbridos AF-646 e AF-682, foram submetidos aos testes de germinação, emergência de plântulas em casa de vegetação e envelhecimento acelerado (períodos de 48, 72 ou 96 horas, a 38 ou 41°C), com e sem o uso de solução saturada de NaCl. O teste de envelhecimento acelerado (procedimento tradicional e com solução salina), conduzido com períodos de exposição de 72h e 96h a 38 ou 41°C, apresentou sensibilidade suficiente para detectar diferenças no potencial fisiológico de lotes de sementes de melão. A utilização de solução saturada de NaCl contribui para reduzir a absorção de água pelas sementes durante o teste de envelhecimento acelerado, permitiu obter resultados menos drásticos e mais uniformes, sem afetar a eficiência do teste