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This paper proposes a new primary lazy update protocol, PTCS (Primary Transaction Commit Schedule). In the PTCS protocol, a serializable primary transaction schedule is generated firstly and then the secondary transactions are committed according to the serializable primary transaction schedule. PTCS protocol can guarantee serializability if the data copy graph contains no directed circles. It can also be extended to eliminate all requirements on the data copy graph. Compared to earlier works, PTCS protocol not only imposes a much weaker requirement on the data placement, but also avoids the deadlock caused by transaction waits and extra message overhead. The performance experiments show that the degradation of the performance caused by the replica management of the PTCS protocol is tolerable.

The current network protecting methods are ineffective in controlling the hosts onf intranet. This paper first analyzes the threats coming from intranet. Then designs and implements an intranet security detecting system which can detect if the intranet is working in a secure state. Finally, it combines the detecting results of this system and those of the vulnerability scanners, constructs a logical modal to evaluate the security of the intranet. This modal integrates as much as the factors that affect the securtiy of intranet, including the vulnerabilities of each host, hosts connected to the Internet illegally, hosts connected to the intranet unauthorized, the filtering rules of the firewall as well as the trust relations among hosts, so it can provide a more reasonable evaluation to the intranet security.

In order to improve precision of software static testing based on defect patterns, inter-function information was extended and applied in software static testing. Pre-function information includes two parts, the effect of context to invoked function and the constraint of invoked function to context, which can be used to detect the common defects, such as null pointer defect, un-initial defect, dangling pointer defect, illegal operation defect, out of bounds defect and so on. Experiments show that, pre-function information can reduce false negative in software static testing effectively.

This paper presents a method, control-flow interval iteration in presence of interprocedural side-effect analysis, to improve test precision in software testing based on defect patterns, then an exact interval computation can be used in defect test algorithm of DTS. Our experiment shows that the DTS, using this method, can reduce the false positive rate and drop defect rate effectively.

Data is replicated at multiple network nodes for performance and availability. Primary lazy replica update protocols have become popular for their superior performance characteristics. A common problem with those lazy replication protocols is that the number of exchanged messages and the deadlock probability drastically increase when the number of sites increases. We propose a method to minimize the copy graph, which can improve the scalability of the replicated system. The copy graph can be decomposed into blocks. If the serializability of each blocks of the copy graph is guaranteed, the serializability of the copy graph is also guaranteed. An algorithm to discover the cut vertices and the blocks of G is introduced. Its running time is /spl Theta/((/spl epsiv/-v+1)/spl epsiv/). For each block of G, if it contains a directed circle, the primary transaction may need to wait to get serializable schedules, and then it will lose the main advantage of the lazy replica update protocols. Therefore it is important to discover the directed circles in the blocks of G. A linear-time algorithm to compute the strongly connected components is also introduced.

The paper deals with the modal analysis of Francis turbine blade with fluid-structure interaction (FSI). The dynamic equation of Francis turbine blade in air and operating flow path is studied, and two different governing equations are solved together. Then the mathematic model for vibration and stress analysis was built to calculate the natural frequency in air by using finite element analysis (FEA). In addition, the blade's coupled modelling in operating flow path lies on a classical finite element discretisation of the coupled fluid-structure equation. According to the analysis of results, the influential coefficients by the FEA adopted in the present study are in fairly good agreement with the experienced data listed in some documents. The modal analysis of the blade highlights that the natural frequencies decrease dramatically and the mode shapes in operating flow path are close to those in air. So the method presented herein can be used efficiently as a reliable tool for the fatigue reliability design and performance analysis of Francis turbine blade.