Search

O III SINEPLA propiciou oportunidades de reflexão acerca do ensino, da avaliação e da formação de professores de PLA em diferentes contextos, em especial, nesta edição, relacionando essas temáticas com uma perspectiva pluricêntrica da língua portuguesa. Como se pode ver nos capítulos deste livro, que representam parte das apresentações e dos debates ocorridos nos três dias do evento, as discussões versaram sobre o ensino de PLA para fins e públicos específicos, a reflexão linguística, a formação de professores, o uso de textos literários em aulas de PLA e o exame Celpe-Bras. No contexto acadêmico e político contemporâneo em que se celebra a adoção de uma perspectiva de Português como língua pluricêntrica e cientes dos diferentes posicionamentos acerca do uso desse conceito pelos profissionais da linguagem, entendemos que o debate deva seguir ampliando a compreensão da complexidade de fatores envolvidos na nomeação das línguas com as quais trabalhamos e nas possíveis implicações de seu uso. É fundamental que possamos compreender as ideologias de linguagem que sustentam nossas práticas e estarmos atentos aos interesses dos projetos educacionais aos quais nos filiamos.

This paper presents a bidirectional multilevel dc–dc power converter for electric vehicle (EV) battery charging. The operating principle of the power converter was presented, analyzed, and experimentally validated under normal and fault conditions. The topology under study was integrated into a bipolar dc grid through the split dc-link of the bidirectional multilevel dc–dc power converter. Considering the failures that can occur in the bipolar dc grid, i.e., in each wire of the bipolar dc grid (positive, negative, and neutral), it was experimentally verified that the dc–dc power converter ensures that the EV battery-charging process continues, regardless of the occurrence or absence of open-circuit failures. In light of this fact, the proposed control algorithms and the presented topology were validated through a set of considerable simulation and experimental results, analyzing the distinct states of the power semiconductors, which compose the bidirectional multilevel dc–dc power converter, for distinct conditions of operation. The developed laboratory prototype of the bidirectional multilevel dc–dc power converter for EV battery charging, which was implemented to obtain the experimental results, is described in detail in this paper. The experimental validation was carried out for the main different fault conditions in the bipolar dc grid in terms of open-circuit failures and, moreover, considering the steady-state and transient-state operations of the dc–dc power converter. The experimental analysis demonstrated that even in the presence of failures in the positive, negative, or neutral wires of the bipolar dc grid, the bidirectional multilevel dc–dc power converter guarantees the correct EV battery-charging operation., This work has been supported by FCT–Fundação para a Ciência e Tecnologia within the R&D Units Project Scope: UIDB/00319/2020. This work has been supported by the MEGASOLAR Project POCI-01-0247-FEDER-047220.

With the constant increase of power converters in industry, the study and comparison of control techniques for these converters are of paramount importance to optimize their functioning, as well as to improve their efficiency. This paper presents a comparison of the most relevant digital control techniques of pulse-width modulation and current control for a modular multilevel converter (MMC), which is a power converter that is increasing in popularity among researchers, and with a steady growth in its literature. Beginning with a theoretical presentation of each control technique and using explanatory figures and computational results, the focus of this paper is the understanding of the modulation and control techniques for the MMC. Since the MMC has a modular structure, the power is distributed among the different submodules, which increases the complexity of the control system. Furthermore, a balancing strategy for the voltage across the capacitor of each submodule of the MMC is also presented. Along with the paper, computer simulations are presented, which were carried out to validate the functioning of the MMC and the control techniques, as well as to understand the differences in the obtained results.

When it comes to power railway systems, two main aspects must be considered: (i) the power of the propulsion of the train, which is responsible for the movement of the train; (ii) the power of the auxiliary services, which is responsible for the power inside the train for commodity and service of the passengers. As such, two different converters are used, namely the propulsion converter and the static converter, respectively. This paper proposes a new topology of a static converter, using a modular multilevel converter with high frequency output, with a high frequency transformer to reduce the size of the converter. The output of the converter is responsible for creating a stable singlephase voltage, with nominal values of 230 V - 50 Hz, from a highly variant input voltage available on the DC-link.

The differential diagnosis of dorsal thoracic pain can be a challange due to the proximity of the dorsal column to vital organs as well as to its unique anatomy, innervation, and rib joint. The patterns of referred visceral pain require, in most cases, extensive complementary diagnostic tests in order to exclude severe conditions. Referred pain patterns often result in numerous and expensive visceral workups in order to exclude serious conditions, and costovertebral joint osteoarthritis is usually only considered when the origin of the pain remains unexplained. The authors present the case of a 40-year-old man with disabling dorsal pain due to isolated costovertebral osteoarthrosis. The symptomatology was controlled after injection of methylprednisolone guided by computed tomography. This clinical case aims to describe the clinical presentation of a rare entity that should be considered in the differential diagnosis of back pain. Resumo O diagnóstico diferencial de dorsalgia revela-se um desafio pela proximidade da coluna dorsal a órgãos vitais assim como por sua anatomia única, inervação e articulação com as costelas. Os padrões de dor referida visceral obrigam, na maioria das vezes, a extensivos exames complementares de diagnóstico de forma a excluir condições graves. A osteoartrose da articulação costovertebral é um diagnóstico pouco reconhecido, e habitualmente é somente considerado quando a fonte de dor continua sem explicação após extensa investigação. Os autores apresentam o caso de um homem de 40 anos de idade com dor dorsal incapacitante devido a osteoartrose costovertebral isolada. A sintomatologia foi controlada após a injeção de metilprednisolona guiada por tomografia computadorizada. Este caso clínico tem como objetivo descrever a apresentação clínica de uma entidade rara que deverá ser considerada no diagnóstico diferencial de dorsalgia.