Otto Engine: Classical and Quantum Approach

In this paper, we analyze the total work extracted and the efficiency of the magnetic Otto cycle in its classic and quantum versions. As a general result, we found that the work and efficiency of the classical engine is always greater than or equal to that of its quantum counterpart independent of the working substance. In the classical case, this is due to the fact that the working substance is always in thermodynamic equilibrium at each point of the cycle, maximizing the energy extracted in the adiabatic paths. We apply this analysis to the case of a two-level system, finding that the work and efficiency in Otto's quantum and classical cycle are identical, regardless of the working substance, and we obtain similar results for a multilevel system where a linear relationship between the spectrum of energies of the working substance and the external magnetic field is fulfilled. Finally, we show an example of a three-level system in which we compare two zones in the entropy, temperature and magnetic field diagram to find which is the most efficient when performing a thermodynamic cycle. This work provides a practical way to look for temperature and magnetic field zones in the entropy diagram that can maximize the power extracted from Otto's magnetic engine

Guidelines for Weighting Factors Adjustment in Finite State Model Predictive Control of Power Converters and Drives

INTERNATIONAL CONFERENCE ON INDUSTRIAL TECHNOLOGY () (.2009.VICTORIA, AUSTRALIA)Model Predictive Control with a finite control set has emerged as a promising control tool for power converters and drives. One of the major advantages is the possibility to control several system variables with a single control law, by including them with appropriate weighting factors. However, at the present state of the art, these coefficients are determined empirically. There is no analytical or numerical method proposed yet to obtain an optimal solution. In addition, the empirical method is not always straightforward, and no procedures have been reported. This paper presents a first approach to a set of guidelines that reduce the uncertainty of this process. First a classification of different types of cost functions and weighting factors is presented. Then the different steps of the empirical process are explained. Finally, results for several power converters and drives applications are analyzed, which show the effectiveness of the proposed guidelines to reach appropriate weighting factors and control performance

Biodegradable chelate enhances the phytoextraction of copper by Oenothera picensis grown in copper-contaminated acid soils

Oenothera picensis plants grow in the acid soils contaminated by copper smelting in the coastal region of central Chile. We evaluated the effects of the biodegradable chelate MGDA on copper extraction by O. picensis and on leaching of copper through the soil profile, using an ex situ experiment with soil columns of varying heights. MGDA was applied in two doses, one month apart, at concentrations of 0 (control), 2, 6 and 10 mmol plant-1. MGDA application significantly increased biomass production and foliar concentration, permitting an effective increase in copper extraction, from 0.09 mg plant-1 in the control, to 1.3 mg plant-1 in the 6 and 10 mmol plant-1 treatments. With 10 mmol plant-1 of MGDA, the copper concentration in the leachate from the 30 cm columns was 20 times higher than in the control. For the 60 cm columns, copper concentration was 2 times higher than the control. It can be concluded that at increased soil depths, copper leaching would be minimal and that MGDA applications at the studied concentrations would not pose a high risk for leaching into groundwater. It can thus be stated that applications of MGDA are an effective and environmentally safe way to improve copper extraction by O. picensis in these soils

Preservación digital de objetos sonoros patrimoniales en Chile.

The following is an updated overview of the experiences regarding the digital preservation of digital audio objects in Chile, based on the collection of information in public and private heritage centers. The evidence shows that these institutions generally follow the conceptual and management guidelines proposed by international organizations and experts in the area. However, the institutions are not aligned in their efforts to preserve their sound heritage. Therefore, there is a need to take action, share best practices, and coordinate work standards, among others things

Predictive control of a back-to-back NPC converter-based wind power system

© 2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other worksAs wind power technology points to increase power ratings, the implementation based on a permanent-magnet synchronous generator (PMSG) with a full-power converter is expanding its market share. Multilevel converters, as for example, neutral-point clamped (NPC) converters, are therefore well suited for this application. Predictive current control presents similar dynamic response and reference tracking than other well-established control methods, but working at lower switching frequencies, and providing extensive flexibility to apply either online or offline different control laws to the same plant. In this work, the predictive current control is applied to both sides of the back-to-back NPC converter connecting a permanent-magnet synchronous wind power generator to the grid. DC-link neutral-point balance is achieved by means of the predictive control algorithm, which considers the redundant switching states of the back-to-back NPC converter. Reduced number of commutations, current spectrum control, and compliance with the low-voltage ride-through (LVRT) requirement are carried out with the predictive control. The obtained experimental results confirm the suitability of the proposed control approach.Peer ReviewedPostprint (author's final draft

Control methods for low voltage ride-through compliance in grid-connected NPC converter based wind power systems using predictive control

This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder.In presence of grid voltage dips, Low Voltage Ride-Through (LVRT) requirements demand the wind power plant to remain connected to the grid, helping the network to keep voltage and frequency stable. Neutral-Point-Clamped (NPC) converters are appropriate for wind power systems, because the current trend of increasing voltage levels. Predictive current control presents as fast dynamic response and accurate reference tracking as other well established control methods, while providing more flexibility. In this work, three different control strategies are applied to the grid-side NPC converter, in order to fulfil LVRT requirements, which are implemented with the predictive current control technique. Dc-link neutral point voltage is kept balanced by the predictive control algorithm, using the redundant switching states of the NPC converter. Simulation results confirm the validity of the proposed control approach.Peer ReviewedPostprint (published version

Research Data in Astronomy: Assessing its Impact and Visibility through a Bibliometric Analysis

In the context of the Open Access and Open Science initiatives, Research Data Management becomes relevant and of current interest to researchers, libraries, and institutions that contribute to the development of scientific knowledge. Particularly in Astronomy, it is a challenge to convert, standardize, process, and arrange large volumes of information and data (estimated in several petabytes), coming from the results of astronomical observations, astronomical catalogs, computational codes, among others, which constitute a fundamental initial step in scientific research [1]. Due to this, and the limited studies on this subject, a bibliometric methodology was applied to analyze indexed datasets in the Data Citation Index (Web of Science, Clarivate Analytics) in the Astronomy & Astrophysics category, for the period 2010-2019, allowing to identify annual evolutions, countries, and institutions with higher productivity, main repositories, and hosting platforms used in publications indexed in Web of Science. The analysis was complemented with InCites (Clarivate Analytics) bibliometric tools to determine the linkage of the publications with the datasets and their impact. The results from this study show a substantial increase in the number of indexed datasets provided by institutions in the United States, United Kingdom, Spain, and Chile, during the analyzed period. In turn, the publications that cite the main datasets show superior performances in the number of citations and the standardized impact, among other productivity and impact metrics

Estudio para el mejoramiento del turismo en la ciudad de Latacunga provincia de Cotopaxi para el año 2010-2011

La presente tesis es un documento escrito producto de la investigación de campo que fue realizada por sus autores y trata de posibilitar el mejoramiento del turismo en la ciudad de Latacunga, provincia de Cotopaxi; el cual buscaba identificar acciones y estrategias en función del desarrollo turístico. A este trabajo se lo dividido en tres capítulos, los cuales de una manera secuencial y ordenada han ayudado para que la investigación cuente con una fundamentación teórica adecuada y que bajo un sistema de investigación descriptiva nos sirvió como referente para poder desarrollar un Plan de Marketing turístico. Nuestro Plan de Marketing se lo desarrollado en función del Marketing Mix, bajo el estudio de producto, plaza, precio y promoción, sabiendo que para una correcta aplicación de este plan se debió realizar como primer paso una encuesta dirigida a la población Latacungueña, un inventario pormenorizado de todos los lugares turísticos con que cuenta la ciudad y el Cantón, que nos proporciono importante información acerca del potencial turístico con el que se cuenta, lo que nos direccionó a una correcta aplicación del marketing táctico y estratégico, con la finalidad de aportar a la creación de nuevas fuentes de trabajo, mejor difusión de sitios turísticos existentes y la reactivación del aparato económico productivo de la ciudad de Latacunga

La disrupción de lo presencial a lo virtual. Percepciones de los directores de docencia sobre el uso de plataformas digitales en contexto de pandemia en una universidad del norte de Chile

As a result of the COVID-19 pandemic, educational practice at different levels of the system was altered and subjected to a contingency situation that forced teachers to use technological tools and strategies for teaching in a virtual context. The purpose of this study is to describe the transition from face-to-face teaching to remote emergency education and the difficulties this presented for academics at the Universidad Arturo Prat (UNAP) in Chile, in terms of the use of available technologies for the development of teaching activities in the context of the pandemic. Qualitative research is developed to characterize the disposition and problems that the academics evidenced regarding remote teaching, through the perceptions of the teaching directors. The results show that academics have transferred the format of their face-to-face classes to virtuality, thus generating the application of a new teaching format in remote modality. Likewise, there is a differentiated use of the available digital technologies according to the age groups of the teachers.Producto de la pandemia de COVID-19, la práctica educativa en los distintos niveles del sistema se vio alterada y sometida a una situación de contingencia que obligó a los docentes a usar herramientas tecnológicas y estrategias para la enseñanza en un contexto de virtualidad. El presente estudio tiene como finalidad describir el paso de una docencia presencial a una educación remota de emergencia y las dificultades que presentó esto para los académicos de la Universidad Arturo Prat (UNAP) de Chile, en cuanto al uso de las tecnologías disponibles para el desarrollo de las actividades lectivas en el contexto de la pandemia. Se desarrolla una investigación de carácter cualitativo, para caracterizar la disposición y problemáticas que evidenciaron los académicos frente a la enseñanza remota, a través de las percepciones de los directores de docencia. Los resultados muestran que los académicos han trasladado el formato de sus clases presenciales a la virtualidad, generando con ello la aplicación de un nuevo formato docente en modalidad remota. Asimismo, se demuestra un uso diferenciado de las tecnologías digitales disponibles según los tramos de edad de los docentes.Como resultado da pandemia global Covid-19, a prática educacional em diferentes níveis do sistema foi alterada e submetida a uma situação de contingência que obrigou os professores a usarem ferramentas e estratégias tecnológicas para o ensino em um contexto virtual. O objetivo deste estudo é descrever a transição do ensino presencial para uma emergência remota e as dificuldades que este apresenta para os acadêmicos da Universidade Arturo Prat, em termos da utilização das tecnologias disponíveis para o desenvolvimento da atividade docente em o contexto da pandemia. Atendendo ao objetivo anterior, optou-se por desenvolver uma pesquisa qualitativa, para caracterizar a disposição e os problemas que os acadêmicos apresentavam diante do ensino a distância. Os resultados mostram que os acadêmicos transferiram o formato de suas aulas presenciais para a virtualidade, o que está impactando no desenvolvimento da aprendizagem e na aquisição de competências dos alunos. Da mesma forma, demonstra-se um uso diferenciado das tecnologias digitais disponíveis em função das faixas etárias dos professores