289 research outputs found
Flexible operation of low-inertia power systems connected via high voltage direct current interconnectors
The replacement of conventional synchronous generators with converter-interfaced generation units calls for increased amounts of flexibility. This paper proposes a novel formulation of the security-constrained unit commitment (SCUC) model applied to a multi-area power system connected via High Voltage Direct Current (HVDC) links. From a system perspective, this paper provides a critical analysis of the synergies and differences between the exploitation of thermostatic loads and HVDC links when providing different layers of flexibility to the system. The former units operate within a local dimension, while the latter enable cross-border exchange of flexibility. Eight different ancillary services are modelled to tackle generation/load outages and uncertainty/variability in renewable energy output. The model is applied to the Great Britain network, which is connected to the Irish network and to the one in Continental Europe. Results suggest a critical review of the operation of future low-carbon HVDC-interconnected systems. Feasibility studies on the benefit for interconnection should no longer neglect considerations on local post-fault frequency dynamics in each area of the system. Then, fundamental changes to the mechanisms that price ancillary services become necessary in order to align these mechanisms with the technical needs of the system
Overlap distributions for quantum quenches in the anisotropic Heisenberg chain
The dynamics after a quantum quench is determined by the weights of the
initial state in the eigenspectrum of the final Hamiltonian, i.e., by the
distribution of overlaps in the energy spectrum. We present an analysis of such
overlap distributions for quenches of the anisotropy parameter in the
one-dimensional anisotropic spin-1/2 Heisenberg model (XXZ chain). We provide
an overview of the form of the overlap distribution for quenches from various
initial anisotropies to various final ones, using numerical exact
diagonalization. We show that if the system is prepared in the
antiferromagnetic N\'eel state (infinite anisotropy) and released into a
non-interacting setup (zero anisotropy, XX point) only a small fraction of the
final eigenstates gives contributions to the post-quench dynamics, and that
these eigenstates have identical overlap magnitudes. We derive expressions for
the overlaps, and present the selection rules that determine the final
eigenstates having nonzero overlap. We use these results to derive concise
expressions for time-dependent quantities (Loschmidt echo, longitudinal and
transverse correlators) after the quench. We use perturbative analyses to
understand the overlap distribution for quenches from infinite to small nonzero
anisotropies, and for quenches from large to zero anisotropy.Comment: 23 pages, 8 figure
Prenatal diagnosis and follow-up of a case of branchio-oto-renal syndrome displays renal growth impairment after the second trimester
Branchio-oto-renal syndrome combines branchial arch defects, hearing impairment and renal malformations or hypoplasia. Due to the high phenotypic variability, prenatal diagnosis has a limited prognostic value in mutation-positive cases. We report the first branchio-oto-renal syndrome molecular prenatal diagnosis and ultrasonographic follow-up, showing a normal renal growth until the 24th week of pregnancy, a growth deceleration during the third trimester and a renal volume recovery during the first months of life
Effects of diet on casein and fatty acid profiles of milk from goats differing in genotype for αS1-casein synthesis
This study investigated the interactions between
nutrition and the genotype at αS1-CN loci (CSN1S1) in
goats, evaluating the impact of fresh forage-based diets
and an energy supplement on the casein and fatty acid (FA)
profiles of milk from Girgentana goats. Twelve goats were
selected for having the same genotype at the αS2-CN, ÎČ-
CN, and Îș-CN loci and differing in the CSN1S1 genotype:
homozygous for strong alleles (AA) or heterozygous for
strong and weak alleles (AF). Goats of each genotype were
divided into three groups and, according to a 3 Ă 3 Latin
square design, fed ad libitum three diets: sulla fresh forage
(SFF), SFF plus 800 g/day of barley (SFB), and mixed
hay plus 800 g/day of barley (MHB). The SFB diet led to
higher-energy intake and milk yield. The energy-supplemented
diets (SFB, MHB) reduced milk fat and urea and
increased coagulation time. The fresh forage diets (SFF,
SFB) increased dry matter (DM) and crude protein (CP)
intake and milk ÎČ-CN. Diet had a more pronounced effect
than CSN1S1 genotype on milk FA profile, which was
healthier from goats fed the SFF diet, due to the higher content
of rumenic acid, polyunsaturated, and omega-3 FAs.
The AA milk had longer coagulation time and higher curd
firmness, higher short- and medium-chain FAs (SMFA),
and lower oleic acid than AF milk. Significant diet by genotype
interactions indicated the higher milk yield of AA
goats than AF goats with the higher-energy SFB diet and
the lower synthesis of SMFA in AF than in AA goats with
the SFF diet
Second Trimester Amniocentesis Is Not a Risk Factor for Very Low Birth Weight and Extremely Low Birth Weight
Objectives. To assess the risk of very low birth weight (VLBW) and extremely low birth weight (ELBW) attributable to second trimester amniocentesis. Methods. Records of 4,877 consecutive amniocentesis, performed between 1997 and 2003, were analyzed. Only VLBW and ELBW in the study population (exposed) and in the control group (unexposed) were evaluated. Comparisons were made between the amniocentesis group versus nonexposed. Odds ratios (OR) and 95% confidence intervals (95% CI) were calculated for VLBW and ELBW classes. Results. In the study population, the VLBW were 35 (0.71%) and the ELBW were 20 (0.41%). In the control group, the VLBW were 220 (0.67%) and the ELBW were 112 (0.34%). The Odds ratios of the VLBW between the study and the control group did not show any statistical significant risk (OR = 1.07, 95% CI = 0.72â1.54). Also in ELBW odds ratios between study and control group were not statistically significant (OR = 1.20, 95% CI = 0.7â1.95). Conclusions. No effect of the second trimester amniocentesis was noted on VLBW and ELBW
Intuitive Robot Teleoperation through Multi-Sensor Informed Mixed Reality Visual Aids
© 2021 The Author(s). This work is licensed under a Creative Commons Attribution 4.0 License. For more information, see https://creativecommons.org/licenses/by/4.0/.Mobile robotic systems have evolved to include sensors capable of truthfully describing robot status and operating environment as accurately and reliably as never before. This possibility is challenged by effective sensor data exploitation, because of the cognitive load an operator is exposed to, due to the large amount of data and time-dependency constraints. This paper addresses this challenge in remote-vehicle teleoperation by proposing an intuitive way to present sensor data to users by means of using mixed reality and visual aids within the user interface. We propose a method for organizing information presentation and a set of visual aids to facilitate visual communication of data in teleoperation control panels. The resulting sensor-information presentation appears coherent and intuitive, making it easier for an operator to catch and comprehend information meaning. This increases situational awareness and speeds up decision-making. Our method is implemented on a real mobile robotic system operating outdoor equipped with on-board internal and external sensors, GPS, and a reconstructed 3D graphical model provided by an assistant drone. Experimentation verified feasibility while intuitive and comprehensive visual communication was confirmed through a qualitative assessment, which encourages further developments.Peer reviewe
Development of a front-end electronics for an innovative monitor chamber for high-intensity charged particle beams
A multi-gap ionization monitor chamber has been
developed by INFN and Torino University, for monitoring of
high intensity pulsed charged particle beams. The read-out
of the chamber is based on a 64-channel ASIC, designed in
CMOS 0.35ÎŒm technology which features for each channel
an independent current-to-frequency converter followed by a
synchronous counter. The chip was designed for connecting each
channel to a different detector element. However, high beam
intensities may lead to an input current above the saturation
level of a single channel. A novel readout has been tested where
all the input channels of the chip have been connected in parallel
to the same detector element allowing to reach 64-times higher
input current with only a modest deterioration of the resolution.
Results will be presented in terms of linearity and noise, and will
be compared to a simulation where the chip is modeled as a set
of independent and uncorrelated channels
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