44,052 research outputs found
Jet-dominated quiescent state in black hole X-ray binaries: the cases of A0620--00 and XTE J1118+480
The radiative mechanism of the black hole X-ray transients (BHXTs) in their
quiescent states (defined as the 2-10 keV X-ray luminosity ) remains unclear. In this work, we investigate the
quasi-simultaneous quiescent state spectrum (including radio, infrared,
optical, ultraviolet and X-ray) of two BHXTs, A0620--00 and XTE J1118+480. We
find that, these two sources can be well described by a coupled accretion --
jet model. More specifically, most of the emission (radio up-to infrared, and
the X-ray waveband) comes from the collimated relativistic jet. Emission from
hot accretion flow is totally insignificant, and it can only be observed in
mid-infrared (the synchrotron peak). Emission from the outer cold disc is only
evident in UV band. These results are consistent with our previous
investigation on the quiescent state of V404 Cyg, and confirm that the
quiescent state is jet-dominated.Comment: 11 pages, 1 figure, accepted for publication in Research in Astronomy
and Astrophysic
Pervasive computing at tableside : a wireless web-based ordering system
Purpose – The purpose of this paper is to introduce a wireless web-based ordering system called iMenu in the restaurant industry. Design/methodology/approach – By using wireless devices such as personal digital assistants and WebPads, this system realizes the paradigm of pervasive computing at tableside. Detailed system requirements, design, implementation and evaluation of iMenu are presented.Findings – The evaluation of iMenu shows it explicitly increases productivity of restaurant staff. It also has other desirable features such as integration, interoperation and scalability. Compared to traditional restaurant ordering process, by using this system customers get faster and better services, restaurant staff cooperate more efficiently with less working mistakes, and enterprise owners thus receive more business profits. Originality/value – While many researchers have explored using wireless web-based information systems in different industries, this paper presents a system that employs wireless multi-tiered web-based architecture to build pervasive computing systems. Instead of discussing theoretical issues on pervasive computing, we focus on practical issues of developing a real system, such as choosing of web-based architecture, design of input methods in small screens, and response time in wireless web-based systems.<br /
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