Distance protection algorithm for multiterminal HVDC systems using the Hilbert–Huang transform

Multiterminal high-voltage direct current (HVDC) systems still need advances in terms of protection in order to improve their reliability. In this context, the distance protection can play a major role by adding selectivity to the existing DC fault detection algorithms. Hence, the present work proposes a non-unit DC distance protection algorithm that uses the frequency of the DC voltage transient oscillation to estimate the distance of the fault. The DC voltage transient frequency is extracted using the Hilbert–Huang transform and compared with a pre-defined frequency/distance curve. The technique was evaluated by simulating faults in a four-terminal symmetric monopole multiterminal HVDC system. In the simulation environment the algorithm was fully selective for faults within the first protection zone and had a correct operation rate of 94% or more for faults located in the second protection zone. To further validate the presented technique, the proposed algorithm was embedded in a digital signal controller, running in real-time. In all performed tests in hardware, the faults were correctly detected and identified as being internal or external. The results indicate that the proposed algorithm could be used in real-world applications, in conjunction with fault detection techniques, adding selectivity to multiterminal DC protection schemes

An approximated analytical model for pole-to-ground faults in symmetrical monopole MMC-HVDC systems

Developing pole-to-ground (PG) fault models for Modular Multilevel Converters (MMC) is not straightforward due to the fault asymmetry and converter switching concerning blocking characteristics. Various studies have been carried out regarding transient simulation of PG faults. However, there is a lack of analytical models for the first stage of the fault. Therefore, this work proposes an approximated analytical model for PG faults in half-bridge MMCs. Closed-form expressions for the MMC contribution to the fault and the fault current are derived. We show that separating the solutions in different resonant frequencies represents the system dynamics and facilitates the interpretation of the phenomena. When compared to system calculated by Ordinary Differential Equations (ODEs), the proposed model provided a good approximation for a wide range of parameters. When compared to the full PSCAD solution, the analytical model was able to precisely calculate the peak fault current value, which confirmed its validity

A list of land plants of Parque Nacional do Caparaó, Brazil, highlights the presence of sampling gaps within this protected area

Brazilian protected areas are essential for plant conservation in the Atlantic Forest domain, one of the 36 global biodiversity hotspots. A major challenge for improving conservation actions is to know the plant richness, protected by these areas. Online databases offer an accessible way to build plant species lists and to provide relevant information about biodiversity. A list of land plants of “Parque Nacional do Caparaó” (PNC) was previously built using online databases and published on the website "Catálogo de Plantas das Unidades de Conservação do Brasil." Here, we provide and discuss additional information about plant species richness, endemism and conservation in the PNC that could not be included in the List. We documented 1,791 species of land plants as occurring in PNC, of which 63 are cited as threatened (CR, EN or VU) by the Brazilian National Red List, seven as data deficient (DD) and five as priorities for conservation. Fifity-one species were possible new ocurrences for ES and MG states

Novel Control Approach for a Hybrid Grid-Forming HVDC Offshore Transmission System

This article describes a hybrid topology of high-voltage direct current (HVDC) for offshore wind farms using a series connection of a voltage source converter (VSC) and six-pulse diode rectifier (6P-DR). In this topology, the offshore side VSC (OF-VSC) acts as a grid-forming converter to maintain the PCC (point of common coupling) voltage of offshore wind farms (WF) and frequency. In addition, the OF-VSC functions as an active power filter to suppress the 5th, 7th, 11th, and 13th order harmonic current components produced by the 6P-DR, making it almost sinusoidal. Due to the 6P-DR being used in the hybrid converter, this new configuration reduces the total cost of the converters and losses, while preserving the power flow to the onshore gird. Compared to the fully-rated converter and hybrid converter based on a 12-pulse diode rectifier, the power loss and cost are reduced, and in addition, the proposed hybrid converter does not require a phase shift transformer nor a high number of diodes. A 200 MW in an HVDC transmission system using the hybrid configuration was simulated in PSCAD. The results show that the system operated correctly and the harmonic components were filtered

Acute Effects of Whole-Body Vibration on Inflammatory Markers in People with Chronic Obstructive Pulmonary Disease: A Pilot Study

Whole-body vibration (WBV) has gained prominence in the rehabilitation of individuals with chronic obstructive pulmonary disease (COPD) because it is a safe and low intensity exercise that promises beneficial effects on physical performance and quality of life. However, its effects on plasma cytokine levels in COPD are still unclear. The aim of the current study was to investigate the acute effects of WBV on inflammatory biomarkers in people with COPD. Twenty-six participants, COPD people (n=13) and healthy controls (n=13), were included. Both groups performed WBV at amplitude of 2 mm and frequency of vibration of 35 Hz, during six series of 30 seconds. They were assessed for lung function, body composition, 6-minute walking test (6MWT), handgrip strength test, plasma concentrations of interleukin (IL), IL-6, IL-8, and IL-10, and soluble tumor necrosis factor alpha (TNF-α) receptors (sTNFR-1 and sTNFR-2). People with COPD had moderate disease [forced expiratory volume in the first second (FEV1) = 58.1%], as well as a worse performance in the 6MWT. The plasma cytokine profile at rest showed that participants with COPD had higher levels of IL-8 and lower levels of IL-10. After one session of WBV, we found an increased plasma IL-10 level in the COPD group, with similar levels for healthy controls. One session of WBV modified the plasma IL-10 level. No effects were found on the other investigated cytokines

High levels of IgG3 anti ICB2-5 in Plasmodium vivax-infected individuals who did not develop symptoms

Submitted by Luis Andre Morais Mariuba ([email protected]) on 2015-03-18T14:25:28Z No. of bitstreams: 1 1475-2875-12-294.pdf: 2893914 bytes, checksum: bdcac2d36ece10e7c1026caf936cf26e (MD5)Approved for entry into archive by Ycaro Santos ([email protected]) on 2015-03-19T15:25:02Z (GMT) No. of bitstreams: 1 1475-2875-12-294.pdf: 2893914 bytes, checksum: bdcac2d36ece10e7c1026caf936cf26e (MD5)Approved for entry into archive by Ycaro Santos ([email protected]) on 2017-09-06T16:51:46Z (GMT) No. of bitstreams: 1 1475-2875-12-294.pdf: 2893914 bytes, checksum: bdcac2d36ece10e7c1026caf936cf26e (MD5)Made available in DSpace on 2017-09-06T16:51:46Z (GMT). No. of bitstreams: 1 1475-2875-12-294.pdf: 2893914 bytes, checksum: bdcac2d36ece10e7c1026caf936cf26e (MD5) Previous issue date: 2013-08-27Instituto Leonidas e Maria DeaneUniversidade Federal do AmazonasFundação de Medicina Tropical Heitor Vieira Dourado2015-03-19Background: Plasmodium vivax has the potential to infect 2.85 billion individuals worldwide. Nevertheless, the limited number of studies investigating the immune status of individuals living in malaria-endemic areas, as well as the lack of reports investigating serological markers associated with clinical protection, has hampered development of vaccines for P. vivax. It was previously demonstrated that naturally total IgG against the N-terminus of P. vivax merozoite surface protein 1 (Pv-MSP1) was associated with reduced risk of malarial infection. Methods: Immune response against Pv-MSP1 (N-terminus) of 313 residents of the Rio Pardo rural settlement (Amazonas State, Brazil) was evaluated in a cross-sectional and longitudinal follow up over two months (on site) wherein gold standard diagnosis by thick blood smear and rRNA gene-based nested real-time PCR were used to discriminate symptomless Plasmodium vivax-infected individuals who did not develop clinical symptoms during a 2-months from those uninfected ones or who have had acute malaria. The acquisition of antibodies against Pv-MSP1 was also evaluated as survival analysis by prospective study over a year collecting information of new malaria infections in surveillance database. Results: The majority of P. vivax-infected individuals (52-67%) showed immune recognition of the N-terminus of Pv-MSP1. Interesting data on infected individuals who have not developed symptoms, total IgG levels against the N-terminus Pv-MSP1 were age-dependent and the IgG3 levels were significantly higher than levels of subjects had acute malaria or those uninfected ones. The total IgG anti ICB2-5 was detected to be an important factor of protection against new malaria vivax attacks in survival analysis in a prospective survey (p = 0.029). Conclusions: The study findings illustrate the importance of IgG3 associated to 2-months of symptomless in P. vivax infected individuals and open perspectives for the rationale of malaria vaccine designs capable to sustain high levels of IgG3 against polymorphic malaria antigen

Optimization of Plasmodium vivax infection of colonized Amazonian Anopheles darlingi

Abstract Obtaining Plasmodium vivax sporozoites is essential for in vitro culture of liver stage parasites, not only to understand fundamental aspects of parasite biology, but also for drug and vaccine development. A major impediment to establish high-throughput in vitro P. vivax liver stage assays for drug development is obtaining sufficient numbers of sporozoites. To do so, female anopheline mosquitoes have to be fed on blood from P. vivax-infected patients through an artificial membrane-feeding system, which in turns requires a well-established Anopheles colony. In this study we established conditions to provide a robust supply of P. vivax sporozoites. Adding a combination of serum replacement and antibiotics to the membrane-feeding protocol was found to best improve sporozoite production. A simple centrifugation method appears to be a possible tool for rapidly obtaining purified sporozoites with a minimal loss of yield. However, this method needs to be better defined since sporozoite viability and hepatocyte infection were not evaluated

Paracoccidioidomycosis case series with and without central nervous system involvement

INTRODUCTION: Paracoccidioidomycosis (PCM) is the most important systemic mycosis in South America. Central nervous system involvement is potentially fatal and can occur in 12.5% of cases. This paper aims to contribute to the literature describing eight cases of neuroparacoccidioidomycosis (NPMC) and compare their characteristics with patients without neurological involvement, to identify unique characteristics of NPCM. METHODS: A cohort of 213 PCM cases was evaluated at the Infectious Diseases Clinic of the University Hospital, Federal University of Minas Gerais, Brazil, from October 1976 to August 2008. Epidemiological, clinical, laboratory, therapeutic and follow-up data were registered. RESULTS: Eight patients presented NPCM. The observed NPCM prevalence was 3.8%. One patient presented the subacute form of PCM and the other seven presented the chronic form of the disease. The parenchymatous form of NPCM occurred in all patients. 60% of the patients who proceeded from the north/ northeast region of Minas Gerais State developed NPCM. The neurological involvement of a mother and her son was observed. NPCM patients exhibited demographical and clinical profiles similar to what is described in the literature. When NPCM cases were compared to PCM patients, there were differences in relation to origin and positive PCM family history. CONCLUSIONS: The results corroborate the clinical view that the neurological findings are extremely important in the evaluation of PCM patients. Despite the limitations of this study, the differences in relation to patient's origins and family history point to the need of further studies to determine the susceptibility factors involved in the neurological compromise