SRGeJ045359.9+622444: A 55-min Period Eclipsing AM CVn Discovered from a Joint SRG/eROSITA + ZTF Search

AM CVn systems are ultra-compact binaries where a white dwarf accretes from a helium-rich degenerate or semi-degenerate donor. Some AM CVn systems will be among the loudest sources of gravitational waves for the upcoming Laser Interferometer Space Antenna (LISA), yet the formation channel of AM CVns remains uncertain. We report the study and characterisation of a new eclipsing AM CVn, SRGeJ045359.9+622444 (hereafter SRGeJ0453), discovered from a joint SRG/eROSITA and ZTF program to identify cataclysmic variables (CVs). We obtained optical photometry to confirm the eclipse of SRGeJ0453 and determine the orbital period to be $P_\textrm{orb} = 55.0802 \pm 0.0003$ min. We constrain the binary parameters by modeling the high-speed photometry and radial velocity curves and find $M_\textrm{donor} = 0.044 \pm0.024 M_{\odot}$ and $R_\textrm{donor}=0.078 \pm 0.012 R_{\odot}$. The X-ray spectrum is approximated by a power-law model with an unusually flat photon index of $\Gamma\sim 1$ previously seen in magnetic CVs with SRG/eROSITA, but verifying the magnetic nature of SRGeJ0453 requires further investigation. Optical spectroscopy suggests that the donor star of SRGeJ0453 could have initially been a He star or a He white dwarf. SRGeJ0453 is the ninth eclipsing AM CVn system published to date, and its lack of optical outbursts have made it elusive in previous surveys. The discovery of SRGeJ0453 using joint X-ray and optical surveys highlights the potential for discovering similar systems in the near future.Comment: Submitted to Ap

Around the Clock Observations of the Q0957+561 A,B Gravitationally Lensed Quasar II: Results for the second observing season

We report on an observing campaign in March 2001 to monitor the brightness of the later arriving Q0957+561 B image in order to compare with the previously published brightness observations of the (first arriving) A image. The 12 participating observatories provided 3543 image frames which we have analyzed for brightness fluctuations. From our classical methods for time delay determination, we find a 417.09 +/- 0.07 day time delay which should be free of effects due to incomplete sampling. During the campaign period, the quasar brightness was relatively constant and only small fluctuations were found; we compare the structure function for the new data with structure function estimates for the 1995--6 epoch, and show that the structure function is statistically non-stationary. We also examine the data for any evidence of correlated fluctuations at zero lag. We discuss the limits to our ability to measure the cosmological time delay if the quasar's emitting surface is time resolved, as seems likely.Comment: AAS LaTeX, 5 PostScript figure

Mathematical simulation of intelligent control system of metal vacuum sputtering process on the basis of application of multi-agent system

A vacuum sputtering process comprises evaporation of the material and subsequent vapor condensation on the substrates. Getting required and repeatable quality of coatings is challenging task. It depends on capabilities of equipment, type of evaporator, interaction evaporator with the evaporating substance and deposition process. Sputtering process parameters are determined by the ability evaporator to maintain a certain temperature evaporated substance for a long time. Controlling operations sequence of pumping and heating depends on achieving optimum vacuum conditions, in spite of used pumping method. The control system must foresee and identify emerging cracks or damage of the system components. This paper focuses on the development of intelligent control system vacuum process on the agent-based approach. © IDOSI Publications, 2013

Mathematical simulation of intelligent control system of metal vacuum sputtering process on the basis of application of multi-agent system

A vacuum sputtering process comprises evaporation of the material and subsequent vapor condensation on the substrates. Getting required and repeatable quality of coatings is challenging task. It depends on capabilities of equipment, type of evaporator, interaction evaporator with the evaporating substance and deposition process. Sputtering process parameters are determined by the ability evaporator to maintain a certain temperature evaporated substance for a long time. Controlling operations sequence of pumping and heating depends on achieving optimum vacuum conditions, in spite of used pumping method. The control system must foresee and identify emerging cracks or damage of the system components. This paper focuses on the development of intelligent control system vacuum process on the agent-based approach. © IDOSI Publications, 2013

Reversing Place Transition Nets

Petri nets are a well-known model of concurrency and provide an ideal setting for the study of fundamental aspects in concurrent systems. Despite their simplicity, they still lack a satisfactory causally reversible semantics. We develop such semantics for Place/Transitions Petri nets (P/T nets) based on two observations. Firstly, a net that explicitly expresses causality and conflict among events, for example an occurrence net, can be straightforwardly reversed by adding a reverse transition for each of its forward transitions. Secondly, given a P/T net the standard unfolding construction associates with it an occurrence net that preserves all of its computation. Consequently, the reversible semantics of a P/T net can be obtained as the reversible semantics of its unfolding. We show that such reversible behaviour can be expressed as a finite net whose tokens are coloured by causal histories. Colours in our encoding resemble the causal memories that are typical in reversible process calculi

Structural Operational Semantics London, UK

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