16 research outputs found
The LOFAR EoR Data Model:(I) Effects of Noise and Instrumental Corruptions on the 21-cm Reionization Signal-Extraction Strategy
The LOFAR EoR Data Model:(I) Effects of Noise and Instrumental Corruptions on the 21-cm Reionization Signal-Extraction Strategy
The LOFAR EoR Data Model:(I) Effects of Noise and Instrumental Corruptions on the 21-cm Reionization Signal-Extraction Strategy
The mathematical analysis for peristaltic flow of nano fluid in a curved channel with compliant walls
Quantized magnetic vortices driven by electric current determine key electromagnetic
properties of superconductors. While the dynamic behavior of slow vortices has been
thoroughly investigated, the physics of ultrafast vortices under strong currents remains
largely unexplored. Here, we use a nanoscale scanning superconducting quantum
interference device to image vortices penetrating into a superconducting Pb film at rates of
tens of GHz and moving with velocities of up to tens of km/s, which are not only much larger
than the speed of sound but also exceed the pair-breaking speed limit of superconducting
condensate. These experiments reveal formation of mesoscopic vortex channels which
undergo cascades of bifurcations as the current and magnetic field increase. Our
numerical simulations predict metamorphosis of fast Abrikosov vortices into mixed
Abrikosov-Josephson vortices at even higher velocities. This work offers an insight into the
fundamental physics of dynamic vortex states of superconductors at high current densities,
crucial for many applications
Simulating the 21 cm forest detectable with LOFAR and SKA in the spectra of high-z GRBs
Large scale structure and cosmolog
Optimal utilization of the terminal for bulk cargo unloading
This paper analyses the capacity of a bulk cargo unloading river terminal, i.e. the existing terminal configuration with two unloading devices (operation without a help strategy and under a complete help strategy between unloading devices) and the predicted future terminal configuration with three unloading devices operating under a partial help strategy. The optimization procedure to determine unloading terminal optimal utilization, for each terminal configuration and operation strategy (existing and future situation) is also shown, due to the fact that ports (terminals) operation under an optimal capacity provides prompt accommodation of vessels with the minimum port waiting time and maximum use of berth facilities. For the purpose of a comprehensive analysis, three different river terminal simulation models have been developed due to the number of unloading devices and their operation strategy. Some of the obtained results have been applied and verified on the existing system
The LOFAR EoR Data Model: (I) Effects of Noise and Instrumental Corruptions on the 21-cm Reionization Signal-Extraction Strategy
the Epoch of Reionization (EoR). The common denominator of these experiments are the large data sets produced, contaminated by various instrumental effects, ionospheric distortions, RFI and strong Galactic and extragalactic foregrounds. In this paper, the first in a series, we present the Data Model that will be the basis of the signal analysis for the LOFAR (Low Frequency Array) EoR Key Science Project (LOFAR EoR KSP). Using this data model we simulate realistic visibility data sets over a wide frequency band, taking properly into account all currently known instrumental corruptions (e.g. direction-dependent gains, complex gains, polarization effects, noise, etc). We then apply primary calibration errors to the data in a statistical sense, assuming that the calibration errors are random Gaussian variates at a level consistent with our current knowledge based on observations with the LOFAR Core Station 1. Our aim is to demonstrate how the systematics of an interferometric measurement affect the quality of the calibrated data, how errors correlate and propagate, and in the long run how this can lead to new calibration strategies. We present results of these simulations and the inversion process and extraction procedure. We also discuss some general properties of the coherency matrix and Jones formalism that might prove useful in solving the calibration problem of aperture synthesis arrays. We conclude that even in the presence of realistic noise and instrumental errors, the statistical signature of the EoR signal can be detected by LOFAR with relatively small errors. A detailed study of the statistical properties of our data model and more complex instrumental models will be considered in the future
Onset, evolution, and magnetic braking of vortex lattice instabilities in nanostructured superconducting films
The LOFAR EoR Data Model: (I) Effects of Noise and Instrumental Corruptions on the 21-cm Reionization Signal-Extraction Strategy
the Epoch of Reionization (EoR). The common denominator of these experiments are the large
data sets produced, contaminated by various instrumental effects, ionospheric distortions, RFI
and strong Galactic and extragalactic foregrounds. In this paper, the first in a series, we present
the Data Model that will be the basis of the signal analysis for the LOFAR (Low Frequency
Array) EoR Key Science Project (LOFAR EoR KSP). Using this data model we simulate realistic
visibility data sets over a wide frequency band, taking properly into account all currently
known instrumental corruptions (e.g. direction-dependent gains, complex gains, polarization
effects, noise, etc). We then apply primary calibration errors to the data in a statistical sense,
assuming that the calibration errors are random Gaussian variates at a level consistent with
our current knowledge based on observations with the LOFAR Core Station 1. Our aim is to
demonstrate how the systematics of an interferometric measurement affect the quality of the
calibrated data, how errors correlate and propagate, and in the long run how this can lead to
new calibration strategies. We present results of these simulations and the inversion process
and extraction procedure. We also discuss some general properties of the coherency matrix
and Jones formalism that might prove useful in solving the calibration problem of aperture
synthesis arrays. We conclude that even in the presence of realistic noise and instrumental
errors, the statistical signature of the EoR signal can be detected by LOFAR with relatively
small errors. A detailed study of the statistical properties of our data model and more complex
instrumental models will be considered in the future.