957 research outputs found
Design of master and slave modules on battery management system for electric vehicles
Nowadays, electric vehicle usage and the use of LiFePO4 batteries in electric vehicles gradually increase. However, there are important features to be considered to use these batteries safely and efficiently. Incorrect use of these batteries can lead to burning, explosion or shortening of the life of batteries.
In this paper, a Battery Management System (BMS) for lithium based batteries is designed that operates more efficiently and communicates with UART between master and slave modules and can communicate via CAN protocol with external devices. Micro controller based control and protection equipment is designed that help to measure and monitor the voltage, temperature and current values of the batteries. They protect the battery cells from the conditions such as over charge, over discharge, high current, high temperature. BMS balances battery cell voltages during charging process with passive cell voltage balancing. In addition to the main controller module in the BMS, slave controller modules have been added to provide high resolution voltage and temperature tracking. A modular BMS has been devised which can be used in groups of batteries of different voltage values thanks to electrically isolated slave control modules
Do meteoritic silicon carbide grains originate from asymptotic giant branch stars of super-solar metallicity?
We compare literature data for the isotopic ratios of Zr, Sr, and Ba from
analysis of single meteoritic stardust silicon carbide (SiC) grains to new
predictions for the slow neutron-capture process (the s process) in metal-rich
asymptotic giant branch (AGB) stars. The models have initial metallicities Z =
0.014 (solar) and Z = 0.03 (twice-solar) and initial masses 2 - 4.5 Msun,
selected such as the condition C/O>1 for the formation of SiC is achieved.
Because of the higher Fe abundance, the twice-solar metallicity models result
in a lower number of total free neutrons released by the 13C({\alpha},n)16O
neutron source. Furthermore, the highest-mass (4 - 4.5 Msun) AGB stars of
twice-solar metallicity present a milder activation of the 22Ne({\alpha},n)25Mg
neutron source than their solar metallicity counterparts, due to cooler
temperatures resulting from the effect of higher opacities. They also have a
lower amount of the 13C neutron source than the lower-mass models, following
their smaller He-rich region. The combination of these different effects allows
our AGB models of twice-solar metallicity to provide a match to the SiC data
without the need to consider large variations in the features of the 13C
neutron source nor neutron-capture processes different from the s process. This
raises the question if the AGB parent stars of meteoritic SiC grains were in
fact on average of twice-solar metallicity. The heavier-than-solar Si and Ti
isotopic ratios in the same grains are in qualitative agreement with an origin
in stars of super-solar metallicity because of the chemical evolution of the
Galaxy. Further, the SiC dust mass ejected from C-rich AGB stars is predicted
to significantly increase with increasing the metallicity.Comment: 40 pages, 7 figures, 1 table. Accepted for publication on Geochimica
Cosmochimica Act
A chemical signature from fast-rotating low-metallicity massive stars: ROA 276 in ω Centauri
© 2017. The American Astronomical Society. All rights reserved. We present a chemical abundance analysis of a metal-poor star, ROA 276, in the stellar system ω Centauri. We confirm that this star has an unusually high [Sr/Ba] abundance ratio. Additionally, ROA 276 exhibits remarkably high abundance ratios, [X/Fe] , for all elements from Cu to Mo along with normal abundance ratios for the elements from Ba to Pb. The chemical abundance pattern of ROA 276, relative to a primordial ω Cen star ROA 46, is best fit by a fast-rotating low-metallicity massive stellar model of 20 , [Fe/H] = -1.8, and an initial rotation 0.4 times the critical value; no other nucleosynthetic source can match the neutron-capture element distribution. ROA 276 arguably offers the most definitive proof to date that fast-rotating massive stars contributed to the production of heavy elements in the early universe
Crystal structure of a heterotetrameric NMDA receptor ion channel
N-Methyl-D-aspartate (NMDA) receptors belong to the family of ionotropic glutamate receptors, which mediate most excitatory synaptic transmission in mammalian brains. Calcium permeation triggered by activation of NMDA receptors is the pivotal event for initiation of neuronal plasticity. Here, we show the crystal structure of the intact heterotetrameric GluN1-GluN2B NMDA receptor ion channel at 4 angstroms. The NMDA receptors are arranged as a dimer of GluN1-GluN2B heterodimers with the twofold symmetry axis running through the entire molecule composed of an amino terminal domain (ATD), a ligand-binding domain (LBD), and a transmembrane domain (TMD). The ATD and LBD are much more highly packed in the NMDA receptors than non-NMDA receptors, which may explain why ATD regulates ion channel activity in NMDA receptors but not in non-NMDA receptors
Evaluation of left renal vein and inferior vena cava variations through routine abdominal multi-slice computed tomography
Background: The aim of this study was to evaluate the frequency of left renal vein (LRV) and inferior vena cava (IVC) variations and the effect of gender on this frequency, as well as the presence of associated abdominal pathologies.Materials and methods: Multi-slice computed tomography (MSCT) images from 746 patients were evaluated retrospectively.Results: Left renal vein variations were identified in 9.8% of cases, while retroaortic LRV (RLRV) and circumaortic LRV (CLRV) were found in 7.4% and 2.4% of cases, respectively. No significant correlation was found between gender and LRV variations (p = 0.797). Of the cases with LRV and IVC variations, 73% had abdominal pathologies, the most common of which were nephrolithiasis, which appeared in 18 (32%) cases, and renal cysts, which appeared in 14 (25.4%) cases.Conclusions: MSCT is a rapid and reliable method of identifying LRV and IVC variations and associated abdominal pathologies
FREQUENCY RATIO ASSESSMENT FOR LANDSLIDES TRIGGERED BY 6 FEBRUARY 2023 KAHRAMANMARAS TURKIYE EARTHQUAKES BETWEEN GOLBASI AND ERKENEK
Landslides triggered by earthquakes are significant geological hazards that can have devastating consequences, posing risks to human lives, infrastructure, and the environment. These seismic events may cause the instability of slopes and result in the displacement of soil and rock materials, leading to landslides. It is crucial to understand the characteristics and mechanisms of earthquake-triggered landslides in order to effectively manage and mitigate their associated risks. The number of landslides triggered by the 2023 Kahramanmaraş earthquakes (with magnitudes of 7.7 and 7.6) was over three thousand and their destructive effects were also devastating as secondary hazards. This study aims to examine the characteristics of landslides using the frequency ratio (FR) model. A landslide susceptibility map (LSM) was also produced using the output. For this purpose, in this study, we derived landslides triggered by the earthquakes in a part of the earthquake-affected region, between Golbasi town of Adiyaman and Erkenek village of Malatya covering an area with a size of 625 km2. The study utilized a landslide inventory that was manually delineated by visual interpretation based on pre-event and post-event. These associations can serve as a foundation for the application of various data-driven machine learning techniques. The findings of this study will contribute to the development of accurate LSMs, providing crucial insights into the behavior of earthquake-triggered landslides
Early time-locked gamma response and gender specificity
Cataloged from PDF version of article.The aim was to investigate whether gender is a causative factor in the gamma status according to which some individuals respond with time-locked, early gamma response, G+, while the others do not show this response, G-. The sample consisted of 42 volunteer participants (between 19 and 37 years of age with at least 9 years of education). There were 22 females and 20 males. Data were collected under the oddball paradigm. Auditory stimulation (10 ms r/f time, 50 ms duration, 65 dB SPL) consisted of target (2000 Hz; p = .20) stimuli that occurred randomly within a series of standard stimuli (1000 Hz; p = .80). Gamma responses were studied in the amplitude frequency characteristics, in the digitally filtered event-related potentials (f-ERPs) and in the distributions which were obtained using the recently developed time-frequency component analysis (TFCA) technique. Participants were classified into G+ and G- groups with a criterion of full agreement between the results of an automated gamma detection technique and expert opinion. The 2 × 2 × 2 ANOVA on f-ERPs and 2 × 2 × 2 multivariate ANOVA on TFCA distributions showed the main effect of gamma status and gender as significant, and the interaction between gamma status and gender as nonsignificant. Accordingly, individual difference in gamma status is a reliable phenomenon, but this does not depend on gender. There are conflicting findings in the literature concerning the effect of gender on ERP components (N100, P300). The present study showed that if the gamma status is not included in research designs, it may produce a confounding effect on ERP parameters. © 2005 Elsevier B.V. All rights reserved
Chemical abundances in giants stars of the tidally disrupted globular cluster NGC 6712 from high-resolution infrared spectroscopy
We present abundances of C, N, O, F, Na, and Fe in six giant stars of the
tidally disrupted globular cluster NGC 6712. The abundances were derived by
comparing synthetic spectra with high resolution infrared spectra obtained with
the Phoenix spectrograph on the Gemini South telescope. We find large
star-to-star abundance variations of the elements C, N, O, F, and Na. NGC 6712
and M4 are the only globular clusters in which F has been measured in more than
two stars, and both clusters reveal F abundance variations whose amplitude is
comparable to, or exceeds, that of O, a pattern which may be produced in M >
5M_sun AGB stars. Within the limited samples, the F abundance in globular
clusters is lower than in field and bulge stars at the same metallicity. NGC
6712 and Pal 5 are tidally disrupted globular clusters whose red giant members
exhibit O and Na abundance variations not seen in comparable metallicity field
stars. Therefore, globular clusters like NGC 6712 and Pal 5 cannot contribute
many field stars and/or field stars do not form in environments with chemical
enrichment histories like that of NGC 6712 and Pal 5. Although our sample size
is small, from the amplitude of the O and Na abundance variations, we infer a
large initial cluster mass and tentatively confirm that NGC 6712 was once one
of the most massive globular clusters in our Galaxy.Comment: Accepted for publication in Ap
HI in four star-forming low-luminosity E/S0 and S0 galaxies
We present HI data cubes of four low-luminosity early-type galaxies which are
currently forming stars. These galaxies have absolute magnitudes in the range
M_B=-17.9 to -19.9 (H_o=50 km/s/Mpc). Their HI masses range between a few times
10^8 and a few times 10^9 M_sun and the corresponding values for M_HI/L_B are
between 0.07 and 0.42, so these systems are HI rich for their morphological
type. In all four galaxies, the HI is strongly centrally concentrated with high
central HI surface densities, in contrast to what is typically observed in more
luminous early-type galaxies. In two galaxies (NGC 802 and ESO 118-G34), the
kinematics of the HI suggests that the gas is in a strongly warped disk, which
we take as evidence for recent accretion of HI. In the other two galaxies (NGC
2328 and ESO 027-G21) the HI must have been part of the systems for a
considerable time. The HI properties of low-luminosity early-type galaxies
appear to be systematically different from those of many more luminous
early-type galaxies, and we suggest that these differences are due to a
different evolution of the two classes. The star formation history of these
galaxies remains unclear. Their UBV colours and Halpha emission-line strengths
are consistent with having formed stars at a slowly-declining rate for most of
the past 10^10 years. However, the current data do not rule out a small burst
of recent star formation overlaid on an older stellar population.Comment: To appear in AJ, LateX, figures in gif format, paper also available
at http://www.nfra.nl/~morganti/LowLu
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