694 research outputs found
A new interpretation of the period-luminosity sequences of long-period variables
Period-luminosity (PL) sequences of long period variables (LPVs) are commonly
interpreted as different pulsation modes, but there is disagreement on the
modal assignment. Here, we re-examine the observed PL sequences in the Large
Magellanic Cloud, including the sequence of long secondary periods (LSPs), and
their associated pulsation modes. Firstly, we theoretically model the sequences
using linear, radial, non-adiabatic pulsation models and a population synthesis
model of the LMC red giants. Then, we use a semi-empirical approach to assign
modes to the pulsation sequences by exploiting observed multi-mode pulsators.
As a result of the combined approaches, we consistently find that sequences B
and C both correspond to first overtone pulsation, although there
are some fundamental mode pulsators at low luminosities on both sequences. The
masses of these fundamental mode pulsators are larger at a given luminosity
than the mass of the first overtone pulsators. These two sequences B and
C are separated by a small period interval in which large amplitude
pulsation in a long secondary period (sequence D variability) occurs, meaning
that the first overtone pulsation is not seen as the primary mode of pulsation.
Observationally, this leads to the splitting of the first overtone pulsation
sequence into the two observed sequences B and C. Our two
independent examinations also show that sequences A, A and C
correspond to third overtone, second overtone and fundamental mode pulsation,
respectively.Comment: 10 pages, 7 figures, accepted for publication in Ap
QoT Computation for 100G Lightpaths Routed on 10G-loaded Dispersion-Managed Network Segments
The core and backbone optical network market segment is largely dominated by coherent transmission delivering 100Gbps and beyond thanks to the DSP-based coherent transceivers technology optical line systems without chromatic dispersion compensation. The metro and access segment instead is still often made of dispersion-compensated optical line systems operated with cheap 10G transceivers because of the still excessive CAPEX required to upgrade this segment to coherent technology. In the context of the gradual rise of SDN technology, aimed at dynamically, transparently and automatically managing and orchestrating optical networks, the ability to route 100G coherent channels through a section of dispersion managed network populated with legacy 10G channels enables more flexibility and CAPEX savings. In this work we propose a simple, fast and conservative quality-of-transmission estimator, tailored to the needs of a software module for optical path computation, able to estimate of the 10G-to-100G non-linear effects
Growth performance and oxidative status in piglets supplemented with verbascoside and teupolioside
Two hundred forty piglets, half female and half barrows, 8.1 ± 1.40 kg LW, were divided into 6 experimental groups and fed ad libitum with a diet supplemented with the following levels of antioxidants: 0 (CON + = positive control added with 100 mg lincomicine/kg), 5 (LT = low teupolioside or LV = low verbascoside), 10 (HT = high teupolioside; HV = high verbascoside; LT+LV) mg/kg of diet for 56 days. Body weight and feed intake were recorded on d0, 14 and 56 of the trial. Ten piglets from each group were selected and blood collected by anterior vena cava puncture at 0, 14 and 56 d for reactive oxygen metabolite (ROMs) determination. HV showed final weight higher than the other groups (P<0.05), and oxidative stability was improved by both integrations of verbascoside. These results support the view that Verbascoside influences the growth performances and oxidative status of piglets
A sensory study on loin quality from pigs slaughtered at 120 or 160 kg liveweight
Effects of different slaughter weights (160 vs. 120 kg) on chemical, physical and sensory characteristics of pig loin were investigated. Physical and chemical traits were similar for the two typologies of weight, whereas lower values of moisture (P<0.01) and higher fat content (P<0.05) were found in heavy pork loin; furthermore increased slaughter weight resulted in redder, more yellow and intensive colour (P<0.05). A selected and trained panel carried out difference from control test showing that heavy pig loin scored higher for appearance and taste parameters (P<0.05), but lower for tenderness (P<0.05). Heavy pig loin was redder, more marbling, wetter, sweeter, and saltier and had higher metallic flavour and lower tenderness
Effects of temperature and mounting configuration on the dynamic parameters identification of industrial robots
Dynamic parameters are crucial for the definition of high-fidelity models of industrial manipulators. However, since they are often partially unknown, a mathematical model able to identify them is discussed and validated with the UR3 and the UR5 collaborative robots from Universal Robots. According to the acquired experimental data, this procedure allows for reducing the error on the estimated joint torques of about 90% with respect to the one obtained using only the information provided by the manufacturer. The present research also highlights how changes in the robot operating conditions affect its dynamic behavior. In particular, the identification process has been applied to a data set obtained commanding the same trajectory multiple times to both robots under rising joints temperatures. Average reductions of the viscous friction coefficients of about 20% and 17% for the UR3 and the UR5 robots, respectively, have been observed. Moreover, it is shown how the manipulator mounting configuration affects the number of the base dynamic parameters necessary to properly estimate the robots’ joints torques. The ability of the proposed model to take into account different mounting configurations is then verified by performing the identification procedure on a data set generated through a digital twin of a UR5 robot mounted on the ceiling
Identification of a UR5 collaborative robot dynamic parameters
The present paper describes an algorithm for the identification of the dynamic parameters of an industrial robot. This approach is based on the possibility to write robot dynamics in a linear form with respect to a specific set of dynamic parameters. To properly detect them, the coefficients of a 5th order Fast Fourier Series (FFS) trajectory have been optimized using a genetic algorithm. Such identification trajectory has been then commanded to a UR5 collaborative robot from Universal Robots and experimental joints torques have been recorded at a frequency of 125Â Hz. Base dynamic parameters were identified using least square errors optimization reaching low standard deviations. The algorithm has been validated with a second persistent trajectory with good results. Temperature effects on friction coefficients have been analyzed by running two identification processes: one just after the first power-up of the robot and the other one after a half an hour warm-up
Selective Hybrid EDFA/Raman Amplifier Placement to Avoid Lightpath Degradation in (C+L) Networks
We investigate optimized placement of hybrid EDFA/Raman amplifiers in (C+L) networks to avoid lightpath degradation due to ISRS. We numerically compare eight strategies for amplifier deployment showing that an optimized placement of Raman amplification can lead to 40% fewer amplifiers compared to baseline deployment practices
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