A SRM for a PV Powered Water Pumping System Based on a Multilevel Converter and DC/DC Dual Output Converter

Trabalho apresentado em 7th International Conference on Smart and Sustainable Technologies - Splitech 2022, 5-8 julho 2022, Bol, CroatiaThis paper focuses on a proposal for a system based on a photovoltaic (PV) supply for a powered water pumping. The system consists in a switched reluctance machine (SRM) controlled by a multilevel converter and fed by PV panels associated to a DC/DC converter. The multilevel power converter proposed to control the SRM was designed to minimize the switches and to support the balance of the two input capacitors. The DC/DC converter consists in a hybrid solution that merges a Buck- Boost converter with a Sepic converter. They use a topology solution in which the input current presents a reduced ripple and only requires one switch. This DC/DC converter is also characterized by a dual output to adapt to the multilevel converter. The control system and a maximum power point tracking (MPPT) algorithm are also presented. The operation of this system will be verified by tests that are done by computer simulations.N/

PV generator-fed water pumping system based on a SRM with a multilevel fault-tolerant converter

This paper presents a pumping system supplied by a PV generator that is based on a switched reluctance machine (SRM). Water pumping systems are fundamental in many applications. Most of them can be used only during the day; therefore, they are highly recommended for use with PV generators. For the interface between the PV panels and the motor, a new multilevel converter is proposed. This converter is designed in order to ensure fault-tolerant capability for open switch faults. The converter is based on two three-level inverters, with some extra switches. Moreover, to reduce the number of switches, the converter is designed to provide inverse currents in the motor windings. Due to the characteristics of this motor, the inverse currents do not change the torque direction. In this way, it was possible to obtain an SRM drive with fault-tolerant capability for transistor faults; it is also a low-cost solution, due to the reduced number of switches and drives. These characteristics of fault-tolerant capability and low cost are important in applications such as water pumping systems supplied by PV generators. The proposed system was verified by several tests that were carried out by a simulation program. The experimental results, obtained from a laboratory prototype, are also presented, with the purpose of validating the simulation tests.info:eu-repo/semantics/publishedVersio

Hybrid Sepic-Ćuk DC-DC Converter Associated to a SRM Drive for a Solar PV Powered Water Pumping System

Este trabalho foi financiado pelo Concurso Anual para Projetos de Investigação, Desenvolvimento, Inovação e Criação Artística (IDI&CA) 2019 do Instituto Politécnico de Lisboa. Código de referência IPL/2019/SOLARPUMP_ISELThe present paper describes a solar photovoltaic (SPV) powered water pumping system employing a switched reluctance motor (SRM) and a merged Sepic-Ćuk DC-DC converter. The proposed solution was designed to use efficiently the available solar energy in order to supply water pumping systems. Solutions of this kind assume a special importance in the current scenario of natural and renewable resources optimization. The proposed DC-DC converter operates in continuous conduction mode (CCM), which combined with a maximum power point tracking (MPPT) controller, helps to optimize the power of the solar photovoltaic panel (SPV). The proposed DC-DC topology is characterized by high voltage static gain when compared with the classical boost topology and reduced voltage stress across the power switch and diodes. Several simulation and experimental results are presented in order to confirm the characteristics of the proposed solution for water pumping systems.info:eu-repo/semantics/publishedVersio

Acetylcholine release and choline uptake by cuttlefish (Sepia officinalis) optic lobe synaptosomes

Acetylcholine (ACh), which is synthesized from choline (Ch), is believed to hold a central place in signaling mechanisms within the central nervous system (CNS) of cuttlefish (Sepia officinalis) and other coleoid cephalopods. Although the main elements required for cholinergic function have been identified in cephalopods, the transmembrane translocation events promoting the release of ACh and the uptake of Ch remain largely unsolved. The ACh release and Ch uptake were quantitatively studied through the use of in vitro chemiluminescence and isotopic methods on a subcellular fraction enriched in synaptic nerve endings (synaptosomes) isolated from cuttlefish optic lobe. The ACh release evoked by K+ depolarization was found to be very high (0.04 pmol ACh.s-(1).mg(-1) protein). In response to stimulation by veratridine, a secretagogue (a substance that induces secretion) that targets voltage-gated Na+ channels, the release rate and the total amount of ACh released were significantly lower, by 10-fold, than the response induced by KCl. The high-affinity uptake of choline was also very high (31 pmol Ch.min(-1).mg(-1) protein). The observed ACh release and Ch uptake patterns are in good agreement with published data on preparations characterized by high levels of ACh metabolism, adding further evidence that ACh acts as a neurotransmitter in cuttlefish optic lobe.FCTPOCTI/BSE/46721/2002SFRH/BPD/14677/2003SFRH/BD/1079/2000SFRH/BD/6403/2001SFRH/BD/18101/2004EC (to Y.D.) - LIPIDIET - QLK1-CT-2002-0017

Foreword

[Excerpt] This book is the forth book of the series of publications entitled “Occupational Safety and Hygiene”. The main contributions for this book were once more from the works that were previously submitted and approved to be presented at the annual symposium of the Portuguese Society of Occupational Safety and Hygiene (SPOSHO), which is celebrating its 12th edition in 2016. The SHO2016—International Symposium on Occupational Safety and Hygiene, similarly to the past eight years, was held in the School of Engineering at University of Minho in Guimarães, Portugal. [...](undefined

Multiscale model for the templated synthesis of mesoporous silica: the essential role of silica oligomers

A detailed theoretical understanding of the synthesis mechanism of periodic mesoporous silica has not yet been achieved. We present results of a multiscale simulation strategy that, for the first time, describes the molecular-level processes behind the formation of silica/surfactant mesophases in the synthesis of templated MCM-41 materials. The parameters of a new coarse-grained explicit-solvent model for the synthesis solution are calibrated with reference to a detailed atomistic model, which itself is based on quantum mechanical calculations. This approach allows us to reach the necessary time and length scales to explicitly simulate the spontaneous formation of mesophase structures while maintaining a level of realism that allows for direct comparison with experimental systems. Our model shows that silica oligomers are a necessary component in the formation of hexagonal liquid crystals from low-concentration surfactant solutions. Because they are multiply charged, silica oligomers are able to bridge adjacent micelles, thus allowing them to overcome their mutual repulsion and form aggregates. This leads the system to phase separate into a dilute solution and a silica/surfactant-rich mesophase, which leads to MCM-41 formation. Before extensive silica condensation takes place, the mesophase structure can be controlled by manipulation of the synthesis conditions. Our modeling results are in close agreement with experimental observations and strongly support a cooperative mechanism for synthesis of this class of materials. This work paves the way for tailored design of nanoporous materials using computational models

Platinum-Triggered Bond-Cleavage of Pentynoyl Amide and N-Propargyl Handles for Drug-Activation.

The ability to create ways to control drug activation at specific tissues while sparing healthy tissues remains a major challenge. The administration of exogenous target-specific triggers offers the potential for traceless release of active drugs on tumor sites from antibody-drug conjugates (ADCs) and caged prodrugs. We have developed a metal-mediated bond-cleavage reaction that uses platinum complexes [K2PtCl4 or Cisplatin (CisPt)] for drug activation. Key to the success of the reaction is a water-promoted activation process that triggers the reactivity of the platinum complexes. Under these conditions, the decaging of pentynoyl tertiary amides and N-propargyls occurs rapidly in aqueous systems. In cells, the protected analogues of cytotoxic drugs 5-fluorouracil (5-FU) and monomethyl auristatin E (MMAE) are partially activated by nontoxic amounts of platinum salts. Additionally, a noninternalizing ADC built with a pentynoyl traceless linker that features a tertiary amide protected MMAE was also decaged in the presence of platinum salts for extracellular drug release in cancer cells. Finally, CisPt-mediated prodrug activation of a propargyl derivative of 5-FU was shown in a colorectal zebrafish xenograft model that led to significant reductions in tumor size. Overall, our results reveal a new metal-based cleavable reaction that expands the application of platinum complexes beyond those in catalysis and cancer therapy.EPSRC studentship for Benjamin Stenton

Aplicação do método de aprendizagem baseado na análise de problemas ao ensino da Fisiopatologia

Educação Médica 1991; 2 (2): 29-40O método de aprendizagem baseado na análise de problemas está a ser utilizado, de uma forma limitada, no ensino da Fisiopatologia desde 1988 e após um ano de preparação dos recursos humanos e materiais. A experiência dos dois primeiros anos revelou que, apesar do método estar apenas a ser aplicado numa única disciplina de um curriculum tradicional, o aproveitamento dos alunos ao longo do ano melhorou e que o mesmo sucedeu no exame final. Os alunos consideraram o método como muito estimulante para a aprendizagem embora trabalhoso. Apesar de terem sido utilizados problemas contendo uma quantidade limitada de informação, os alunos seguiram as várias fases do método de uma forma adequada. No entanto o pessoal docente já decidiu que no próximo ano académico (1991-1992) serão utilizados problemas completos para estimular ainda mais o raciocínio e a aprendizagem num contexto clínico. Summary:A limited version of the problem- based learning method is being used in the discipline of Pathophysiology since 1988 after one year of preparation including both the faculty and the learning materiais. The evaluation of the first two years showed an improvement in the performance of the students both in the final exams and during the year. The students also considered the method very stimulating for learning although they felt the need of an extra effort. Despite the fact that we were using in complete cases the steps of the method were followed. Neverthless the faculty has already decided that in the next academic year (1991-1992), complete cases will be used for further improvement of the reasoning process within the clinical context

A critical assessment of methods for the intrinsic analysis of liquid interfaces: 2. density profiles

Substantial improvements in the molecular level understanding of fluid interfaces have recently been achieved by recognizing the importance of detecting the intrinsic surface of the coexisting condensed phases in computer simulations (i.e., after the removal of corrugations caused by capillary waves) and by developing several methods for identifying the molecules that are indeed located at the boundary of the two phases. In our previous paper [J. Phys. Chem. C 2010, 114, 11169], we critically compared those methods in terms of reliability, robustness, and computation speed. Once the intrinsic surface of a given phase is detected, various profiles, such as the density profiles of the components, can be calculated relative to this intrinsic surface rather than to the macroscopically planar Gibbs dividing surface. As a continuation of our previous study, here we present a detailed and critical comparison of various methods that can be used to calculate intrinsic density profiles once the full set of truly interfacial molecules has been identified. Two of the methods, the Fourier function and the Voronoi tessellation, are already described in the literature; two other methods, the covering surface and the triangular interpolation, are newly proposed algorithms; one method, the modified grid-based intrinsic profile (GIP) method, is an improvement over an existing procedure. The different methods are again compared in terms of accuracy and computational cost. On the basis of this comparison, we propose a fast and accurate protocol to be routinely used for intrinsic surface analyses in computer simulations