Stochastic Coordination of Joint Wind and Photovoltaic Systems with Energy Storage in Day-Ahead Market

This paper presents an optimal bid submission in a day-ahead electricity market for the problem of joint operation of wind with photovoltaic power systems having an energy storage device. Uncertainty not only due to the electricity market price, but also due to wind and photovoltaic powers is one of the main characteristics of this submission. The problem is formulated as a two-stage stochastic programming problem. The optimal bids and the energy flow in the batteries are the first-stage variables and the energy deviation is the second stage variable of the problem. Energy storage is a way to harness renewable energy conversion, allowing the store and discharge of energy at conveniently market prices. A case study with data from the Iberian day-ahead electricity market is presented and a comparison between joint and disjoint operations is discussed

Planning of aircraft fleet maintenance teams

This paper addresses a support information system for the planning of aircraft maintenance teams, assisting maintenance managers in delivering aircraft on time. The developed planning of aircraft maintenance teams is a computer application based on a mathematical programming problem written as a minimization one. The initial decision variables are positive integer variables specifying the allocation of available technicians by skills to maintenance teams. The objective function is a nonlinear function balancing the time spent and costs incurred with aircraft fleet maintenance. The data involves the technicians’ skills, the hours of work to perform maintenance tasks, the costs related to facilities, and the aircraft downtime cost. The realism of this planning entails random possibilities associated with maintenance workload data, and inference by a procedure of Monte Carlo simulation provides a proper set of workloads instead of going through all the possibilities. The based formalization is a nonlinear integer programming problem, converted into an equivalent pure linear integer programming problem, using a transformation from initial positive integer variables to Boolean ones. A case study addresses the use of this support information system for planning a team for aircraft maintenance of three lines under the uncertainty of workloads, and a discussion of results shows the serviceableness of the proposed support information system

Stochastic optimization for the daily joint operation of wind/PV and energy storage

This paper deals with the problem of optimal bidding in a day-ahead market of electricity for a power producer having joint operation of wind with photovoltaic power systems and storage of energy. Uncertainty, not only on electricity market prices, but also on wind and photovoltaic powers, has to be faced in order to achieve optimal bidding. The problem is viewed as a sort of a two-stage stochastic optimization problem formulated by mix-integer linear programming. A case study with data from the Iberian Peninsula is presented and a comparison between joint and disjoint operations is discussed, allowing concluding that the joint operation attenuates the economic impact of disjoint operation volatility

Short-Term Trading for a Wind-PV Power Producer in an Electricity Market

This paper deals with the problem of coordinated trading of wind and photovoltaic systems in order to find the optimal bid to submit in a pool-based electricity market. The coordination of wind and photovoltaic systems presents uncertainties not only due to electricity market prices, but also with wind and photovoltaic power forecast. Electricity markets are characterized by financial penalties in case of deficit or excess of generation. So, the aim o this work is to reduce these financial penalties and maximize the expected profit of the power producer. The problem is formulated as a stochastic linear programming problem. The proposed approach is validated with real data of pool-based electricity market of Iberian Peninsula

Wind power with energy storage arbitrage in day-ahead market by a stochastic MILP approach

This paper is about a support information management system for a wind power (WP) producer having an energy storage system (ESS) and participating in a day-ahead electricity market. Energy storage can play not only a leading role in mitigation of the effect of uncertainty faced by a WP producer, but also allow for conversion of wind energy into electric energy to be stored and then released at favourable hours. This storage provides capability for arbitrage, allowing an increase on profit of a WP producer, but must be supported by a convenient problem formulation. The formulation proposed for the support information management system is based on an approach of stochasticity written as a mixed integer linear programming problem. WP and market prices are considered as stochastic processes represented by a set of scenarios. The charging/discharging of the ESS are considered dependent on scenarios of market prices and on scenarios of WP. The effectiveness of the proposed formulation is tested by comparison of case studies using data from the Iberian Electricity Market. The comparison is in favour of the proposed consideration of stochasticity

Resenha do artigo “Estrutura da dissertação técnica em laboratório de redação em sala de aula sobre violência no trânsito”

This is a review article entitled "Technical dissertation structure in writing laboratory in classroom about traffic violence”. This article is authored by: Isaías Cardoso de Oliveira; Wellinton Dias Gomes. The article reviewed here was published in the periodical  “Revista JRG de Estudos Acadêmicos”. Ano I, Vol. I, n.1, 2018.Esta é uma resenha do artigo intitulado “Estrutura da dissertação técnica em laboratório de redação em sala de aula sobre violência no trânsito”. Este artigo é de autoria de Jonas Rodrigo Gonçalves et al. O artigo aqui resenhado foi publicado no periódico “Revista JRG de Estudos Acadêmicos”. Ano I, Vol. I, n.1, 2018

Social networks, language learning and language school student sojourners: a qualitative study

This thesis investigates individual language school student sojourners’ learning experiences in the UK. It takes into account the importance of learners learning through interaction with others in the target language community and recognises how learners’ social networks affect their language learning and use. There are many studies about students who study abroad for academic purposes and immigrant learners, but not many relating to individual language learners in private language schools. In order to fill this gap, this study focused on individual language school learners. With the intention of understanding how the social networks and language learning interact over time as part of their sojourner experience, I utilised different theoretical frameworks that have been applied to other groups of language learners and concluded that these frameworks are also applicable to private language school students. I recognised that in order to understand my participants’ learning experiences I needed to interact with them and also observe how they interacted with their social world. Therefore, formal interviews (semi-structured) and informal interviews (informal group meeting or chat) were the main methods for my study together with observation of interaction in various situations. This study identified the expectations that learners had with regard to the target language community, host families and native speakers’ attitudes towards foreign students, and the realisation that these expectations were higher than what was actually encountered. It also identified the steps the individual language learners took to overcome these disappointments and how they reconstructed their relationships with the target language and community respectively. In contrast with many previous studies which only focused on learning from native speakers, my study recognised that learners sometimes can have more interpersonal contact with their fellow students than native speakers. And consequently they benefit more from these contacts, in terms of language learning, than from native speakers. This thesis also helps language learners and language educators recognise basic theoretical frameworks which could help them evaluate the benefits and problems related to learning through interpersonal contact. And with this understanding learners will be able to facilitate their autonomous learning in the target language community

Aplicativo com fenômenos do cotidiano para desenvolvimento dos conceitos de Física Moderna

A luz de novas pesquisas que fomentam o crescimento tecnológico no século XXI, é cada vez mais comum a procura de professores de toda a rede de ensino por novas metodologias que o auxiliem na facilitação do processo de ensino e aprendizagem. De acordo com (UNESCO, 2010) essas tecnologias digitais estão inseridas na nossa sociedade em todos os âmbitos da vida e vieram para ficar. Então a grande exclamação, é sobre como a escola pode utilizar melhor a tecnologia para que essas tenham maior eficácia quando atreladas a educação. A partir de toda essa perspectiva tecnológica, verifica-se o crescente fluxo de descobertas na última década, que fez com que a Física Moderna ganhasse espaços avassaladores nos noticiários, nos meios de pesquisa, programas de mestrado e doutorado e até no mercado de trabalho. O estado do Acre, por exemplo, onde está localizada a universidade onde propomos a criação do aplicativo e também a aplicação do mesmo, segundo (ANATEL, 2019), foi referência crescente no desenvolvimento de fibra óptica. E se a física moderna presente nesse e em outros fenômenos é a explicação para grande parte das tecnologias presentes no mundo, por que não utilizar delas próprias para a disseminação do conteúdo que mais apresenta defasagem na rede de ensino regular?  O manuseio de maneira correta dessa onda crescente de dispositivos conectados à internet dentro das escolas, se dará nesta pesquisa, pela abordagem de Ensino Aprendizagem, focalizado em David Ausubel, Psicólogo da Educação Estadunidense, onde através de um aplicativo direcionado para o ensino de física, especificamente ao conteúdo de física moderna, o aluno do Ensino Médio, será capaz de desenvolver habilidades de análise comparativa da física abstrata com o cotidiano, assimilando os conceitos científicos com a linguagem diária do aluno. O aplicativo intitulado como Physics Phone, funciona em sistemas operacionais, Android, IOS e Microsoft, podendo ser baixado por todos os alunos da rede pública e privada, com disponibilidade para download gratuita. Vale ressaltar que o aplicativo é uma obra em andamento, autoria do próprio autor deste resumo

Study of Deepfakes in Cyberspace, Impact, and Consequences on the Social Environment

We live in era in which we are inundated with information from both hemispheres, and in which the economy of attention makes us far from the truth. The present study has as its core to study the creation, use, as well as the sharing of videos originated by artificial intelligence that can make it appear that a person says or does something, although he has never said or done anything of the kind, this type of content is called deepfakes. The problem is the way in which these contents are propagated, which for the untrained eye, can be seem as authentic. To prepare the article, we opted for quantitative research, through a survey, and a literature review in books, articles and reports. It was found through the obtained data that many users are linked to the desire to verify the veracity and source of information circulating in digital networks