António Martins
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View article: Vaccination After Haematopoietic Stem Cell Transplant: A Review of the Literature and Proposed Vaccination Protocol
Vaccination After Haematopoietic Stem Cell Transplant: A Review of the Literature and Proposed Vaccination Protocol Open
Background/Objectives: Haematopoietic stem cell transplantation (HCT) induces profound immunosuppression, significantly increasing susceptibility to severe infections. This review examines vaccinations’ necessity, timing, and efficacy post…
View article: Simulation model development and experimental validation of a PFC converter
Simulation model development and experimental validation of a PFC converter Open
The most common interface to the electric grid of small power loads, which is based on a diode bridge followed by a bulk capacitor, generates a large number of low-frequency harmonics in the input current. To comply with the IEC 61000-3-2 …
View article: Double-Side Feeding and Reactive Power Compensation Using the Railway Interline Power Flow Controller
Double-Side Feeding and Reactive Power Compensation Using the Railway Interline Power Flow Controller Open
This paper gives an overview of the operating characteristics of the railway interline power flow controller (RIPFC) regarding the capability of transferring active power between two sections of an electrified railway line separated by a n…
View article: Noma - A Mysterious and Mutilating Disease
Noma - A Mysterious and Mutilating Disease Open
Two Patients having suffered from Noma, a mysterious and mutilating disease, predominant in low income Countries (namely from Africa), still of unknown origin and, requiring a difficult plastic surgical approach, are presented
View article: Balancing the Active Power of a Railway Traction Power Substation with an sp-RPC
Balancing the Active Power of a Railway Traction Power Substation with an sp-RPC Open
The railway system is one of the safest, most efficient, and environmentally friendly means of land transport for people and goods. However, as the demand for mobility has increased, the current railway system has shown some weaknesses, re…
View article: How Anaesthesiology Helped to Fight the First Wave of the COVID-19 Pandemic in Portugal
How Anaesthesiology Helped to Fight the First Wave of the COVID-19 Pandemic in Portugal Open
Introduction: The dissemination of the COVID-19 pandemic in Europe, namely in Portugal, demanded an organizational and clinical reaction from the Portuguese National Health Service. With the unpredictable impact of COVID-19 infected patien…
View article: Recomendações para o Tratamento e Seguimento de Doentes com Febre Q
Recomendações para o Tratamento e Seguimento de Doentes com Febre Q Open
A febre Q (do inglês query fever) é uma zoonose de distribuição mundial transmitida por uma bactéria intracelular Gram negativo, Coxiella burnetii. Os ruminantes domésticos são os principais reservatórios implicados na transmissão da doenç…
View article: Non-COVID-19 respiratory viral infection
Non-COVID-19 respiratory viral infection Open
Implemented control measures brought about by the coronavirus disease 2019 (COVID-19) pandemic have changed the prevalence of other respiratory viruses, often relegating them to a secondary plan. However, it must not be forgotten that a di…
View article: A Comprehensive Review on Modular Multilevel Converters, Submodule Topologies, and Modulation Techniques
A Comprehensive Review on Modular Multilevel Converters, Submodule Topologies, and Modulation Techniques Open
The concept of the modular multilevel converter (MLC) has been raising interest in research in order to improve their performance and applicability. The potential of an MLC is enormous, with a great focus on medium- and high-voltage applic…
View article: Traction power substation balance and losses estimation in AC railways using a power transfer device through Monte Carlo analysis
Traction power substation balance and losses estimation in AC railways using a power transfer device through Monte Carlo analysis Open
The high dynamic power requirements present in modern railway transportation systems raise research challenges for an optimal operation of railway electrification. This paper presents a Monte Carlo analysis on the application of a power tr…
View article: SARS-CoV-2-related Multisystem Inflammatory Syndrome in Adults
SARS-CoV-2-related Multisystem Inflammatory Syndrome in Adults Open
Adults infected with SARS-CoV-2 may develop a multisystem inflammatory syndrome (MIS-A) characterized by elevated inflammatory markers and multisystem organ involvement. We report the case of a patient who presented with fever and vomiting…
View article: Voltage Unbalance, Power Factor and Losses Optimization in Electrified Railways Using an Electronic Balancer
Voltage Unbalance, Power Factor and Losses Optimization in Electrified Railways Using an Electronic Balancer Open
Unbalanced currents, low power factor and high losses contribute to increasing the bill infrastructure managers must pay to the TSO/DSO operator that supplies electric energy to the railway system. Additionally, if regenerative energy comi…
View article: HIV Infection: Time from Diagnosis to Initiation of Antiretroviral Therapy in Portugal, a Multicentric Study
HIV Infection: Time from Diagnosis to Initiation of Antiretroviral Therapy in Portugal, a Multicentric Study Open
The benefits of antiretroviral therapy (ART) for persons living with HIV (PLWH) are well established. Rapid ART initiation can lead to improved clinical outcomes. Portugal has one of the highest rates of new HIV diagnoses in the European U…
View article: Experimental Validation of a Reduced-Scale Rail Power Conditioner Based on Modular Multilevel Converter for AC Railway Power Grids
Experimental Validation of a Reduced-Scale Rail Power Conditioner Based on Modular Multilevel Converter for AC Railway Power Grids Open
Rail power conditioner (RPC) has the ability to improve the power quality in AC railway power grids. This power conditioner can increase the loading capacity of traction substations, balance the active power between the feeder load section…
View article: Eczema herpeticum
Eczema herpeticum Open
View article: New Reactive Power Compensation Strategies for Railway Infrastructure Capacity Increasing
New Reactive Power Compensation Strategies for Railway Infrastructure Capacity Increasing Open
In AC railway electrification systems, the impact of reactive power flow in the feeding voltage magnitude is one aspect contributing to the quality of supply degradation. Specifically, this issue results in limitations in the infrastructur…
View article: Modular Multilevel Converter in Electrified Railway Systems: Applications of Rail Static Frequency Converters and Rail Power Conditioners
Modular Multilevel Converter in Electrified Railway Systems: Applications of Rail Static Frequency Converters and Rail Power Conditioners Open
The Modular Multilevel Converter (MMC) has become the most preferable multilevel converter topology for medium and high-power systems, due to the MMC's high reliability and redundancy. This paper focuses on MMC applications in electrified …
View article: Topologies and Operation Modes of Rail Power Conditioners in AC Traction Grids: Review and Comprehensive Comparison
Topologies and Operation Modes of Rail Power Conditioners in AC Traction Grids: Review and Comprehensive Comparison Open
Electric locomotives in AC traction power systems represent a huge single-phase non-linear load and, detrimentally, affect the power quality and the efficiency of the three-phase power grid. Nevertheless, along the last decades, power elec…
View article: Deadbeat Predictive Current Control for Circulating Currents Reduction in a Modular Multilevel Converter Based Rail Power Conditioner
Deadbeat Predictive Current Control for Circulating Currents Reduction in a Modular Multilevel Converter Based Rail Power Conditioner Open
This paper presents a deadbeat predictive current control methodology to reduce the circulating currents in a modular multilevel converter (MMC) when it operates as a rail power conditioner (RPC) in a conventional railway system-based V/V …
View article: STATCOM Evaluation in Electrified Railway Using V/V and Scott Power Transformers
STATCOM Evaluation in Electrified Railway Using V/V and Scott Power Transformers Open
View article: Optimizing the train-catenary electrical interface in AC railways through dynamic control reconfiguration
Optimizing the train-catenary electrical interface in AC railways through dynamic control reconfiguration Open
The power supply architecture of most AC electric railway vehicles is constituted by transformers and catenaries at increasingly high power levels. Inside the vehicles, the interface between the catenary and the DC-bus of the traction moto…
View article: A Novel Hardware Protection Scheme for a Modular Multilevel Converter Half-Bridge Submodule
A Novel Hardware Protection Scheme for a Modular Multilevel Converter Half-Bridge Submodule Open
The Modular Multilevel Converter (MMC) has become progressively an attractive solution for the medium-power and the high-power applications, due to its modularity, flexibility of redundancy or scalability, high efficiency and low productio…
View article: Cost estimation of rail power conditioner topologies based on indirect modular multilevel converter in v/v and scott power transformers
Cost estimation of rail power conditioner topologies based on indirect modular multilevel converter in v/v and scott power transformers Open
This paper presents a cost estimation study for several rail power conditioner (RPC) topologies based on an indirect modular multilevel converter (MMC), in which these topologies are combined with V/V or Scott power transformers. The RPC t…
View article: A Comprehensive Comparison of Rail Power Conditioners Based on Two-level Converters and a V/V Power Transformer in Railway Traction Power Systems
A Comprehensive Comparison of Rail Power Conditioners Based on Two-level Converters and a V/V Power Transformer in Railway Traction Power Systems Open
<p>Electric locomotives in the traction power systems represent huge nonlinear single-phase loads and they affect adversely the public electrical grid stability and the power quality. Some of such problems are related to the harmonic…
View article: Simplified rail power conditioner based on a half-bridge indirect AC/DC/AC Modular Multilevel Converter and a V/V power transformer
Simplified rail power conditioner based on a half-bridge indirect AC/DC/AC Modular Multilevel Converter and a V/V power transformer Open
This paper presents a comprehensive study about a Simplified Rail Power Conditioner (SRPC) based on a half bridge indirect AC/DC/AC Modular Multilevel Converter (MMC) and a V/V traction power transformer. The proposed system with a half br…
View article: Rail power conditioner based on indirect AC/DC/AC modular multilevel converter using a three-phase V/V power transformer
Rail power conditioner based on indirect AC/DC/AC modular multilevel converter using a three-phase V/V power transformer Open
This paper presents a rail power conditioner (RPC) system based on an indirect AC/DC/AC modular multilevel converter (MMC) where a V/V power transformer is used to feed the main catenary line and the locomotives. The proposed control strat…
View article: Efficiency and cost estimation for a static frequency converter and a rail power conditioner based on an indirect modular multilevel converter in railways applications
Efficiency and cost estimation for a static frequency converter and a rail power conditioner based on an indirect modular multilevel converter in railways applications Open
This paper presents a comparative study between two different power electronics solutions for electrified railway substations to overcome some drawbacks which could appear on the public grid side. These drawbacks or troubles on the public …
View article: Input Current Distortion and Output Voltage Regulation of the Boost PFC Converter Operating with Different Control Method
Input Current Distortion and Output Voltage Regulation of the Boost PFC Converter Operating with Different Control Method Open
There are many possible topologies for implementing power factor correction converters. Due to its advantages, the average current control method is one of the most widely used. The critical conduction mode control method is also very used…
View article: Analysis and Characterization of a Square-Wave Modulation Method for Single-Phase Cascaded H-Bridge Multilevel Inverters
Analysis and Characterization of a Square-Wave Modulation Method for Single-Phase Cascaded H-Bridge Multilevel Inverters Open
Cascaded multilevel inverters offer several advantages over other multilevel structures: modularity, high voltage capability, reliability. Additionally, a large number of cascaded inverters using a square wave modulation method allow low l…
View article: Analysis and Energetic Characterization of Low-Power Grid-Connected Photovoltaic Systems
Analysis and Energetic Characterization of Low-Power Grid-Connected Photovoltaic Systems Open
This paper discusses some of the most important Photovoltaic (PV) systems characteristics related to its global efficiency like MPP tracking efficiency, static efficiency, conversion efficiency as well as the Euro efficiency. The losses mo…