1,940 research outputs found
Impact of renewable energy sources on relay protection operation
The current trend of any electric power system is the integration of renewable energy sources (RES). Mostly these are solar and wind power plants. The penetration of renewable energy leads to significant changes in the operating mode of the power system and, accordingly, affects the functioning of the relay protection and automation devices. In particular, the use of renewable energy can lead to a decrease in short-circuit currents and the insensitivity of the protection to this fault. The paper demonstrates the results of a study that confirmed this. In the paper analyzed the existing approaches to setting up relay protection and automation. Based on this analysis, conclusions are made
Multiple system atrophy: diagnostic methods and biomarkers
Multiple system atrophy (MSA) is a neurodegenerative disease belonging to a group of synucleinopathies and characterized by significant autonomic failure, parkinsonian syndrome, and cerebellar signs. Diagnostic criteria used currently were updated in 2022. While the clinical method and neuroimaging are typically diagnostic in MSA, new modalities are currently emerging. Novel candidate biomarkers are being intensively and thoroughly studied.
The review analyzes the clinical picture and diagnostic criteria of the disease, describes imaging methods for diagnosing synucleinopathies, as well as known laboratory markers of multiple system atrophy
SDSS J080434.20+510349.2: Eclipsing WZ Sge-Type Dwarf Nova with Multiple Rebrightenings
We observed the 2006 superoutburst of SDSS J080434.20+510349.2 during its
plateau phase, rebrightening phase, and post-superoutburst final decline. We
found that this object is a grazing eclipsing system with a period of
0.0590048(2) d. Well-defined eclipses were only observed during the late stage
of the superoutburst plateau and the depth decreased during the subsequent
stages. We determined the superhump period during the superoutburst plateau to
be 0.059539(11) d, giving a fractional superhump excess of 0.90(2)%. During the
rebrightening and post-superoutburst phases, persisting superhumps with periods
longer than those of superhumps during the plateau phase: 0.059632(6) during
the rebrightening phase and 0.05969(4) d during the final fading. This
phenomenon is very well in line with the previously known long-period "late
superhumps" in GW Lib, V455 And and WZ Sge. The amplitudes of orbital humps
between different states of rebrightenings suggest that these humps do not
arise from the classical hot spot, but are more likely a result of projection
effect in a high-inclination system. There was no clear evidence for the
enhanced hot spot during the rebrightening phase. We also studied previously
reported "mini-outbursts" in the quiescent state and found evidence that
superhumps were transiently excited during these mini-outbursts. The presence
of grazing eclipses and distinct multiple rebrightenings in SDSS
J080434.20+510349.2 would provide a unique opportunity to understanding the
mechanism of rebrightenings in WZ Sge-type dwarf novae.Comment: 14 pages, 12 figures, PASJ accepte
Discovery of Negative Superhumps during a Superoutburst of January 2011 in ER Ursae Majoris
We report on a discovery of "negative" superhumps during the 2011 January
superoutburst of ER UMa. During the superoutburst which started on 2011 January
16, we detected negative superhumps having a period of 0.062242(9) d, shorter
than the orbital period by 2.2%. No evidence of positive superhumps was
detected during this observation. This finding indicates that the disk
exhibited retrograde precession during this superoutburst, contrary to all
other known cases of superoutbursts. The duration of this superoutburst was
shorter than those of ordinary superoutbursts and the intervals of normal
outbursts were longer than ordinary ones. We suggest a possibility that such
unusual outburst properties are likely a result of the disk tilt, which is
supposed to be a cause of negative superhumps: the tilted disk could prevent
the disk from being filled with materials in the outmost region which is
supposed to be responsible for long-duration superoutbursts in ER UMa-type
dwarf novae. The discovery signifies the importance of the classical prograde
precession in sustaining long-duration superoutbursts. Furthermore, the
presence of pronounced negative superhumps in this system with a high
mass-transfer rate favors the hypothesis that hydrodynamical lift is the cause
of the disk tilt.Comment: 8 pages, 3 figures, Accepted for publication in PASJ Lette
Chronic Triple Infection with Hepatitis B, C, and D Viruses in the Republic of Sakha (Yakutia)
The purpose of this work was to study the features of the clinical course of mixed infections with hepatitis B+C+D viruses in the Republic of Sakha (Yakutia) (RS(Y)).
Materials and Methods: The incidences of these infections were studied in the infectious disease department of the Yakutsk City Clinical Hospital. A total of 74 patients with chronic infection with hepatitis B, C, and D viruses were analyzed. The following markers of HBV (HBsAg, HBeAg, anti-HBcIgG, HBV DNA), HCV (anti-HCV) and HDV (anti-HDV, HDV RNA) were detected. According to PCR (n=35), HCV-RNA was detected in 29(82.8%) patients. In 65.8% of cases, HCV-RNA replication was observed in the absence of HDV-DNA. Mono-replication of HBV (HBV-DNA+, HCV-RNA-) was detected in 17.1% patients, mono-replication of HCV (HBV-DNA-, HCV-RNA+) in 65.7% patients and mixed replication of viruses C, D and/or G (HBV-DNA-, HCV-RNA+, HDV-RNA+/HGV-RNA+) in 17.1% patients.
Results: The comparison of biochemical parameters of patients with chronic mixed hepatitis showed that more expressed changes are observed with the mixed replication than with the mono-replicative form of hepatitis
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