Papers by Author: Wei Xiang Xu

Abstract: The application of high-speed railway data, which is an important component of China's transportation science data sharing, has embodied the typical characteristics of data-intensive computing. A reasonable and effective data placement strategy is needed to deploy and execute data-intensive applications in the cloud computing environment. Study results of current data placement approaches have been analyzed and compared in this paper. Combining the semi-definite programming algorithm with the dynamic interval mapping algorithm, a hierarchical structure data placement strategy is proposed. The semi-definite programming algorithm is suitable for the placement of files with various replications, ensuring that different replications of a file are placed on different storage devices. And the dynamic interval mapping algorithm could guarantee better self-adaptability of the data storage system. It has been proved both by theoretical analysis and experiment demonstration that a hierarchical data placement strategy could guarantee the self-adaptability, data reliability and high-speed data access for large-scale networks.

Abstract: This paper analyzed the existing association rules update algorithm IUA, found out that when the decision makers gave priority attention to the situation of maximum frequent itemsets, this algorithm cannot lower the cost of the database traversal to quickly access to the largest number of frequent itemsets. For the lack of the algorithm, an algorithm which is based on reverse search approach to update association rules is presented. The updating algorithm based on reverse search first generated all frequent itemsets of new itemsets. Then, it spliced the new largest frequent itemsets and original largest frequent itemsets for trimming, get the updated maximal frequent itemsets. This algorithm not only reduces the traversal times in the process of association rules updating, but also realized the priority access to the largest operation of frequent itemsets.

Abstract: The paper investigates kinds of classical Bayes classification arithmetic and summarizes their advantage and disadvantage, then introduces an improved weighted mixed Bayes classification model. It divides attribute sets into several subsets theorem. The subsets are trained by TAN (Tree Augmented Naive Bayes) and the results are integrated by weighted formula. At the same, the paper introduced a new method to compute the weights of attribute subsets. Finally, Experimental results show that this model has higher classification accuracy and practicability．

Abstract: Quadratic TC-Bézier curves with shape parameter is constructed in a special space, it shares most optimal properties as those of the quadratic Bézier curves and its shape can be adjusted by changing the parameter value in . The circle and ellipse can be represented with this curve accurately. Presents G1 condition of quadratic TC-Bézier curves, the results have definite geometric meanings and can be applied to surface modeling conveniently.

Abstract: The methods of pruning have great influence on the effect of the decision tree. By researching on the pruning method based on misclassification, introduced the conception of condition misclassification and improved the standard of pruning. Propose the conditional misclassification pruning method for decision tree optimization and apply it in C4.5 algorithm. The experiment result shows that the condition misclassification pruning can avoid over pruned problem and non-enough pruned problem to some extent and improve the accurate of classification.

Abstract: Track geometry deformation lead to dangerous of train driving, endangering railway transport. It is the prerequisite of developing a reasonable plan of track maintenance and repair that find out the occurrence of track geometry deformation and the law of development. It is also one of the core works of railway's maintenance and repair. In this paper, we analyze detect data of railway track use time series analysis, discovery the track deformation production, make a thorough inquiry to find out the trend of deformation occurrence and forecast the status of the track geometry. The results show that there is higher accuracy of the forecasting, and it can be used to guide the conservation of railway track.

Abstract: Data platform of data sharing and service provide technical support for high-speed railway transportation organization, it provide data parameter and data support for high-speed railway operation management, and it plays an important role in promoting national economic development. In this paper, the metadata theory is used for data storage, data cataloging, data retrieval and data discovery in the management of the Beijing-Shanghai high-speed railway transportation equipment, analyze and propose key technologies of the establishment of data sharing platform based on metadata management of high-speed railway transportation equipment, correlation analysis is made and the result of analysis indicates that data platform can greatly improve the utilization and ability to obtain high-speed railway transportation equipment data. It can also improve the ability to support organizational decision-making of high-speed railway transportation.

Abstract: The research is mainly made on the G1/C1 matching condition of spline curves. On the basis of the analysis on the basic function of T-B spline curves and the features of curve endpoints, we proposed the n+1 order T-B spline basic function and the solving method. The G1/C1 matching condition of C-B spline curves and T-B spline curves is put forward in this paper. On this condition, when matching C-B spline curves and T-B spline curves, the controlling vertexes can be added to make C-B spline curve tangent with the first and last edge by the first and last vertex of controlling polygon. Application instances were put up in this paper which illustrated that the G1/C1 matching between T-B spline curve and C-B spline curve using the feature of T-B spline curve which can represents semiellipse arc (semicircle arc) precisely can solve the problem that C-B spline curve cannot represents semiellipse arc (semicircle arc) precisely.