Quality (QoS) prediction is one of the most important research topics of workflow. In this paper, we propose a stochastic model to evaluate QoS (make-span, reliability and cost) of workflow systems based on QWF-net, which extends traditional WF-net by associating tasks with firing-rate, failure-rate and cost-coefficient. Through a case study, we show that our framework is capable of modeling real-world workflow-based application. Also, Monte-carlo simulation in the case study indicates our analytical methods are consistent with simulation. We also present a sensitivity analysis technique to identify QoS bottleneck.The paper concludes with a comparison between our approach and related work.

We report single crystal growth and physical properties characterization of YbFe 2 Al 10 compounds. The measurements of resistivity, magnetic susceptibility, and specific heat show different behaviors from previous studies on polycrystal samples. An intermediate valent characteristic with moderate mass enhancement is indicated. In particular, the optical spectroscopy measurement reveals formation of multiple hybridization energy gaps which become progressively pronounced at low temperature. The multiple hybridization energy gaps are likely caused by the hybridizations between the flat band from Yb 4 f electrons and different bands of conduction electrons.

After exposure to hydrogen plasma and chemical etching to remove layers of different thicknesses, ntype GaAs wafers with (100) and (110) orientation were deposited with An to form Au/(n GaA-s) Schottky barriers (SB s). After zero-bias annealing (ZBA), the Schottky barrier height (SBH) of the Au/(n-GaAs) SB s containing hydrogen falls; after reverse-bias annealing (RBA), the SBH rises; and the SBH is reversible within experimental precision in at least three ZBA-RBA processes. Furthermore, the control effect of zero-bias annealing and reverse-bias annealing on the Schottky barrier height depends quantitatively on the orientation of the GaAs wafer and the thickness of the layer removed by chemical etching before deposition of Au. But the Schottky-barrier height of a control Schottky-barrier that is not subject to hydrogen exposure changes little during zero-bias annealing or reverse-bias annealing processes. It is also found that besides the SBH the effective Richardson coeScient of the SB containing hydrogen has a one-to-one correlation with the reverse bias of the RBA (100 C, 2 h). Experiments strongly support the fact that the hydrogen contained in the SB is essential for the above ZBA-RBA effect. We have suggested a physical model to explain why hydrogen can reduce the Schottky-barrier heights and result in the ZBA-RBA effect of Au/(n-GaAs) Schottky barriers.