Dissipative solitons characterization in singly resonant optical parametric oscillators: a variational formalism

In this work, the emergence of single-peak temporal dissipative solitons in singly-resonant degenerate optical parametric oscillators is investigated analytically. Applying the Kantarovich optimization method, through a Lagrangian variational formalism, an approximate analytical soliton solution is computed using a parameter-dependent ansatz. This permits to obtain analytical estimations for the dissipative soliton energy, peak power, and existence boundaries, which are of great value for experimentalist. To confirm the validity of this procedure, these analytical results are compared with a numerical study performed in the context of pure quadratic systems, showing a good agreement

Improving the Power Electronics Laboratory teaching/learning process: an interactive web tool

European Higher Education Area; Power Electronics Laboratory; educational methods Resumen: The forthcoming European Higher Education Area implies an important change in the teaching/learning process: it is necessary to get students more involved as well as to promote their independence and active participation. To achieve this objective, the new teaching methodologies aimed at more effective and appropriate learning for professional practice involve the use of audiovisual, computer and multimedia tools on the part of lecturers. Therefore, a web tool, based on a content management system, has been developed for the teaching in Power Electronics Laboratory. Moreover, the use of these multimedia tools makes possible to promote the students independence. Finally, the use of this web tool results in a very significant increase in the motivation students.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Third-order chromatic dispersion stabilizes Kerr frequency combs

Using numerical simulations of an extended Lugiato-Lefever equation, we analyze the stability and nonlinear dynamics of Kerr frequency combs generated in microresonators and fiber resonators taking into account third-order dispersion effects. We show that cavity solitons underlying Kerr frequency combs, normally sensitive to oscillatory and chaotic instabilities, are stabilized in a wide range of parameter space by third-order dispersion. Moreover, we demonstrate how the snaking structure organizing compound states of multiple cavity solitons is qualitatively changed by third-order dispersion, promoting an increased stability of Kerr combs underlined by a single cavity soliton.Comment: 4 pages and 4 figure

Characterization and Defect Analysis of Machined Regions in Al-SiC Metal Matrix Composites Using an Abrasive Water Jet Machining Process

Metal matrix composite (MMC) materials are increasingly used in industrial sectors such as energy, structural, aerospace, and automotive. This is due to the improvement of properties by the addition of reinforcements. Thus, it is possible to obtain properties of higher strength, better rigidity, controlled thermal expansion, and elevated wear resistance. However, due to the extreme hardness achieved during their manufacture, these composites pose a challenge to the conventional machining industry due to the rapid deterioration experienced by cutting tools. This article therefore proposes the use of an unconventional machining method that is becoming increasingly widely used: abrasive water jet cutting. This process is characterized by high production rates, absence of wear, and environmental friendliness, among other advantages. Experimental tests were carried out in order to analyze results that minimize the formation of defects in the machining of metal matrix composite consisting of aluminium matrix with silicon carbide (Al-SiC MMC). To this end, results were analyzed using Scanning Optical and Electron Microscope (SOM/SEM) techniques, the taper angle was calculated, and areas with different surface quality were detected by measuring the roughness

Multimode resonance transition to collapsed snaking in normal dispersion Kerr resonators: Bright versus dark solitons

We study the dynamics of Kerr cavity solitons in the normal dispersion regime, in the presence of an intracavity phase modulation. The associated parabolic potential introduces multimode resonances, which promote the formation of high-order bright solitons. By gradually reducing the potential strength, bright solitons undergo a transition into dark solitons. We describe this process as a shift from a multimode resonance to a collapsed snaking bifurcation structure. This work offers a comprehensive overview of cavity dynamics and may provide a potential pathway to access multi-stable states by effectively varying the phase modulation

Dynamics of three-dimensional spatiotemporal solitons in multimode waveguides

In this work, we present a detailed study of the dynamics and stability of fundamental spatiotemporal solitons emerging in multimode waveguides with a parabolic transverse profile of the linear refractive index. Pulsed beam propagation in these structures can be described by using a Gross-Pitaevskii equation with a two-dimensional parabolic spatial potential. Our investigations are based on comparing variational approaches, based on the Ritz optimization method, with extensive numerical simulations. We found that, with a Kerr self-focusing nonlinearity, spatiotemporal solitons are stable for low pulse energies, where our analytical results find a perfect agreement with the numerical simulations. However, solitons with progressively increasing energies eventually undergo wave collapse, which is not predicted within the variational framework. In a self-defocusing scenario, again for low energies there is good agreement between the variational predictions and simulations. Whereas, for large soliton energies complex spatiotemporal dynamics emerge

Semianalytical calculation of the zonal-flow oscillation frequency in stellarators

Due to their capability to reduce turbulent transport in magnetized plasmas, understanding the dynamics of zonal flows is an important problem in the fusion programme. Since the pioneering work by Rosenbluth and Hinton in axisymmetric tokamaks, it is known that studying the linear and collisionless relaxation of zonal flow perturbations gives valuable information and physical insight. Recently, the problem has been investigated in stellarators and it has been found that in these devices the relaxation process exhibits a characteristic feature: a damped oscillation. The frequency of this oscillation might be a relevant parameter in the regulation of turbulent transport, and therefore its efficient and accurate calculation is important. Although an analytical expression can be derived for the frequency, its numerical evaluation is not simple and has not been exploited systematically so far. Here, a numerical method for its evaluation is considered, and the results are compared with those obtained by calculating the frequency from gyrokinetic simulations. This "semianalytical" approach for the determination of the zonal-flow frequency reveals accurate and faster than the one based on gyrokinetic simulations.Comment: 30 pages, 14 figure

Revisión sistemática para integración de datos en geolocalización

Visita Técnica InternacionalSe realizó una revisión sistemática para la integración de datos en geolocalización con la finalidad de identificar y proponer alternativas de implementación de este concepto en la ciudad de Bogotá. Encontrando que en Colombia es muy poco explotado este concepto, para ello se propone una alternativa por cada sector abarcado, los cuales son educación, turismo y salud, esto es posible gracias a una recolección de información a nivel nacional e internacional donde se descubrió los diferentes componentes que se encuentran involucrados al momento de realizar una implementación de una integración de datos de geolocalización.INTRODUCCIÓN 1. ANTECEDENTES Y JUSTIFICACIÓN 2. PLANTEAMIENTO Y FORMULACIÓN DEL PROBLEMA 3. MARCO DE REFERENCIA 4. OBJETIVOS 5. ALCANCES Y LIMITACIONES 6. METODOLOGÍA 7. DESARROLLO DE LA METODOLOGÍA 8. CONCLUSIONES 9. RECOMENDACIONES BIBLIOGRAFÍA ANEXOSPregradoIngeniero de Sistema

Choice of electronic v/s printed documents by southern Chilean dental students.

In recent decades, the use of digital texts has replaced printed documents. This has generated changes in the way texts are presented and diffused as well as the students’ choice and the way of reading materials related to medicine. While some reports have evaluated the use of digital compared to print formats, there is no evidence about dental students’ preferences. The objective of this study is to determine preferences among dental students from six universities in the south of Chile for using printed versus electronic documents. A descriptive study based on a survey which was conducted among dental students in May and June, 2013, was designed. The proposed survey was adapted for collecting general student data and preferences for using electronic or traditional printed documents. Six schools and a total of 1,022 students, with an average age of 21.4 years, participated. A 93.3% of them reported using both types of documents.  However, a 59.7% preferred printed documents. Only a 9.3% read documents directly from an electronic device. Students overwhelmingly preferred using printed documents than the electronic type. It is imperative to investigate the impact of new learning technologies in Chilean dental education.Keywords: Dentistry, dental education, electronic devices, e-learning, learning technologies.Uso de documentos electrónicos v/s impresos por estudiantes de odontología del sur de Chile.El uso de textos en formato digital ha reemplazado en las últimas décadas el uso de documentos impresos, generando cambios en la disposición y difusión de éstos como también en la elección de los estudiantes y la forma de lectura de materias relacionadas con la medicina. Si bien existen reportes que valoran el uso de formato digital en comparación a textos impresos, no existe evidencia de las preferencias en estudiantes de Odontología. El objetivo de este estudio es determinar la preferencia de uso de documentos en formato impreso versus electrónico en estudiantes de odontología de seis universidades del sur de Chile. Se diseñó un estudio descriptivo basado en una encuesta aplicada a estudiantes de Odontología entre mayo y junio del año 2013. Se adaptó la encuesta propuesta para ello, recolectando datos generales del estudiante, preferencia de uso de documentos electrónicos y documentos tradicionales impresos. Participaron seis escuelas, con un total de 1.022 estudiantes con un promedio de edad de 21.4 años. El 93.3% declara usar ambos tipos de documentos, sin embargo, el 59.7% prefieren el uso de documentos impresos versus documentos electrónicos. Sólo el 9.3% lee directamente los documentos desde un dispositivo electrónico. Los estudiantes prefieren mayoritariamente el uso de documentos impresos por sobre los de tipo electrónicos. Es perentorio investigar el impacto de nuevas tecnologías de aprendizaje en la educación odontológica chilena.Palabras clave: Odontología, educación dental, dispositivos electrónicos, e-learning, tecnologías del aprendizaje

Low-cost Soil Moisture Sensors Based on Inductive Coils Tested on Different Sorts of Soils

[EN] The use of precision agriculture and the Internet of Things has improved the efficiency of many cultures. Nevertheless, there are a few low-cost options to monitor soil moisture. Moreover, those options depend on the specific characteristics of the soil. In this paper, we attempt to find a sensor, based on mutual inductance, that could be used for more than one sort of soil. We study three prototypes, one of them with casing. The sensors are powered with a voltage of 10 peak to peak volts. One of the soils has a high content of organic matter and sand while the other is rich in sand and silt. The best prototype for the soil with high levels of organic matter has 10 turns on the powered coil and 5 on the induced coil. The best frequency for this sensor is 1340 kHz. For the soil with a significant quantity of silt, the best prototype has 80 turns on the powered coil and 40 on the induced coil. The frequency at which this sensor works best is 229 kHz, which happens to be its peak frequency. With those characteristics regressions lines with R2 values higher than 0.75 can be modeledThis work is partially found by the Conselleria de Educación, Cultura y Deporte with the Subvenciones para la contratación de personal investigador en fase postdoctoral, grant number APOSTD/2019/04, by European Union through the ERANETMED (Euromediterranean Cooperation through ERANET joint activities and beyond) project ERANETMED3-227 SMARTWATIR, and by the European Union with the Fondo Europeo Agrícola de Desarrollo Rural (FEADER) Europa invierte en zonas rurales, the MAPAMA, and Comunidad de Madrid with the IMIDRA, under the mark of the PDR-CM 2014-2020 project number PDR18-XEROCESPED.Parra-Boronat, M.; Parra-Boronat, L.; Lloret, J.; Mauri, PV.; Llinares Palacios, JV. (2019). Low-cost Soil Moisture Sensors Based on Inductive Coils Tested on Different Sorts of Soils. IEEE. 616-622. https://doi.org/10.1109/IOTSMS48152.2019.8939258S61662