Search results for "loop"
showing 10 items of 608 documents
Analytical methods for computation of phase-detector characteristics and PLL design
2011
An effective analytical methods for computation of phase detector characteristics are suggested. For high-frequency oscillators new classes of such characteristics are described. Approaches to a rigorous nonlinear analysis of PLL are discussed.
Nonlinear analysis of phase-locked loop
2010
Abstract New method for the rigorous mathematical nonlinear analysis of PLL systems is suggested. This method allows to calculate the characteristics of phase detectors and carry out a rigorous mathematical analysis of transient process and stability of the system.
On the Gardner Problem for the Phase-Locked Loops
2019
This report shows the possibilities of solving the Gardner problem of determining the lock-in range for multidimensional phase-locked loops systems. The development of analogs of classical stability criteria for the cylindrical phase space made it possible to obtain analytical estimates of the lock-in range for third-order system.
Anomalous enhancement of the isospin-violating Λ(1405) production by a triangle singularity in Λc→π+π0π0Σ0
2018
The decay of ${\mathrm{\ensuremath{\Lambda}}}_{c}^{+}$ into ${\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{0}\mathrm{\ensuremath{\Lambda}}(1405)$ with the $\mathrm{\ensuremath{\Lambda}}(1405)$ decay into ${\ensuremath{\pi}}^{0}{\mathrm{\ensuremath{\Sigma}}}^{0}$ through a triangle diagram is studied. This process is initiated by ${\mathrm{\ensuremath{\Lambda}}}_{c}^{+}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\overline{K}}^{*}N$, and then the ${\overline{K}}^{*}$ decays into $\overline{K}\ensuremath{\pi}$ and $\overline{K}N$ produce the $\mathrm{\ensuremath{\Lambda}}(1405)$ through a triangle loop containing ${\overline{K}}^{*}N\overline{K}$ which develops a singularity around 1890 MeV. Th…
Discussion on triangle singularities in the Λb→J/ψK−p reaction
2016
We have analyzed the singularities of a triangle loop integral in detail and derived a formula for an easy evaluation of the triangle singularity on the physical boundary. It is applied to the ${\mathrm{\ensuremath{\Lambda}}}_{b}\ensuremath{\rightarrow}J/\ensuremath{\psi}{K}^{\ensuremath{-}}p$ process via ${\mathrm{\ensuremath{\Lambda}}}^{*}$-charmonium-proton intermediate states. Although the evaluation of absolute rates is not possible, we identify the ${\ensuremath{\chi}}_{c1}$ and the $\ensuremath{\psi}(2S)$ as the relatively most relevant states among all possible charmonia up to the $\ensuremath{\psi}(2S)$. The $\mathrm{\ensuremath{\Lambda}}(1890){\ensuremath{\chi}}_{c1}p$ loop is ver…
The role of radiative losses in the late evolution of pulse-heated coronal loops/strands
2012
Radiative losses from optically thin plasma are an important ingredient for modeling plasma confined in the solar corona. Spectral models are continuously updated to include the emission from more spectral lines, with significant effects on radiative losses, especially around 1 MK. We investigate the effect of changing the radiative losses temperature dependence due to upgrading of spectral codes on predictions obtained from modeling plasma confined in the solar corona. The hydrodynamic simulation of a pulse-heated loop strand is revisited comparing results using an old and a recent radiative losses function. We find significant changes in the plasma evolution during the late phases of plas…
EUV FLICKERING OF SOLAR CORONAL LOOPS: A NEW DIAGNOSTIC OF CORONAL HEATING
2016
A previous work of ours found the best agreement between EUV light curves observed in an active region core (with evidence of super-hot plasma) and those predicted from a model with a random combination of many pulse-heated strands with a power-law energy distribution. We extend that work by including spatially resolved strand modeling and by studying the evolution of emission along the loops in the EUV 94 angstrom and 335 angstrom channels of the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory. Using the best parameters of the previous work as the input of the present one, we find that the amplitude of the random fluctuations driven by the random heat pulses increases …
Large-amplitude Quasiperiodic Pulsations as Evidence of Impulsive Heating in Hot Transient Loop Systems Detected in the EUV with SDO/AIA
2019
Short heat pulses can trigger plasma pressure fronts inside closed magnetic tubes in the corona. The alternation of condensations and rarefactions from the pressure modes drive large-amplitude pulsations in the plasma emission. Here we show the detection of such pulsations along magnetic tubes that brighten transiently in the hot 94A EUV channel of SDO/AIA. The pulsations are consistent with those predicted by hydrodynamic loop modeling, and confirm pulsed heating in the loop system. The comparison of observations and model provides constraints on the heat deposition: a good agreement requires loop twisting and pulses deposited close to the footpoints with a duration of 0.5 min in one loop,…
Numerical modeling and design of a disk-type rotating permanent magnet induction pump
2016
Abstract Electromagnetic induction pumps with rotating permanent magnets appear to be the most promising devices to transport liquid metals in high-temperature applications. Here we present a numerical methodology to simulate the operation of one particular modification of these types of pumps: a disk-type induction pump. The numerical model allows for the calculation and analysis of the flow parameters, including the pressure–flow rate characteristics of the pump. The simulations are based on an iterative fully coupled scheme for electromagnetic and hydrodynamic solvers. The developed model is verified by comparing with experimental data obtained using a Pb-Bi loop test facility, for press…
On the Coronal Temperature in Solar Microflares
2020
We present a study of solar imaging and spectral observations of a microflare, focusing on the temperature diagnostics provided by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory, and the Extreme-Ultraviolet Imaging Spectrometer (EIS) on board Hinode. Our data analysis, in particular from the emission in the 131 and 94 Å channels, indicates that the heated plasma reaches temperatures of ≿10 MK, at odds with a previous analysis of the same event, and we discuss the reason for the discrepancy. A particularly interesting aspect is the likely presence of the Fe XXIII 263.76 Å line, though weak, in EIS spectra in the early phases of the event, supporting the presen…