The limits of parameter γ in FAST TCP are studied in this paper. A continuous time fluid flow model of the link buffer is considered to create a linear control system related to FAST TCP. Linearing the fluid flow model and window control model, the Laplace transform version of congestion control system are presented. It results in a negative feedback system with open loop transfer function. With the analysis of Nyquist curve of the system, a sufficient condition on asymptotical stability of FAST TCP congestion window related to the parameter γ is obtained. Packet level ns-2 simulations are used to verify the theoretical claims.
Composite Web services provide promising prospects for conducting cross-organizational Web service transactions. Such transactions generally require longer processing time and manipulate financially critical data. To efficiently manage these Web services transactions, isolation is commonly relaxed, but inconsistency will be caused by concurrently executing isolation-relaxing transactions. This article proposes an extension to the WS-Business Activity Protocol, which ensures the consistent executions of isolation-relaxing Web service transactions, and which is based on transaction dependency graphs distributed over multiple nodes. Furthermore, this article presents several algorithms implementing the protocol, and introduces the implement of a prototype system.
In this letter, we present a novel approach of valve stiction detection using wavelet technology. A new non-invasive method is developed with the closed-loop normal operating data. The redundant dyadic discrete wavelet transform is used to decompose the data at different resolution scales. Based on the Lipschitz regularity theory, wavelet coefficients analysis across scales is performed to detect the jumps in the controlled variables. Adaptive wavelet de-noising is then applied to the data. Features of the valve stiction patterns are extracted from the de-noised data and the valve stiction probability is calculated.
