Effective pattern discovery for text mining

Many data mining techniques have been proposed for mining useful patterns in text documents. However, how to effectively use and update discovered patterns is still an open research issue, especially in the domain of text mining. Since most existing text mining methods adopted term-based approaches, they all suffer from the problems of polysemy and synonymy. Over the years, people have often held the hypothesis that pattern (or phrase) based approaches should perform better than the term-based ones, but many experiments did not support this hypothesis. This paper presents an innovative technique, effective pattern discovery which includes the processes of pattern deploying and pattern evolving, to improve the effectiveness of using and updating discovered patterns for finding relevant and interesting information. Substantial experiments on RCV1 data collection and TREC topics demonstrate that the proposed solution achieves encouraging performance

Tenders with Different Risk Preferences in Construction Industry

Underlying the fact that different tenderers have different preferences on risk-taking, this study investigates the different tenderers' behaviors in one-shot construction bid auctions. Our model extends the preconditions of previous assumption that all tenderers are characterized by neutral risk-taking in the original tendering model for lowest-price sealed tender. A general tendering model for the lowest-price sealed tender is established to explain the behavior of tenderers during the tendering. The results indicate that construction estimate is affected by the degree of uncertainties in the construction industry. Therefore, in a lowest-price sealed tender, risk-averse tenders would tender a higher price and conversely risk-seeking tenderers would tender a lower price when risk-neutral tenderers would tender a middle price. However, the risk-seeking tenderers are more likely to win the bid.Auction, tender, uncertainty, preference, construction industry

The near wall effect of synthetic jets in a boundary layer

Copyright @ 2007 Elsevier Inc. All rights reserved.An experimental investigation to analyse the qualitative near wall effect of synthetic jets in a laminar boundary layer has been undertaken for the purpose of identifying the types of vortical structures likely to have delayed separation on a 2D circular cylinder model described in this paper. In the first instance, dye visualisation of the synthetic jet was facilitated in conjunction with a stereoscopic imaging system to provide a unique quasi three-dimensional identification of the vortical structures. Secondly, the impact of synthetic jet structures along the wall was analysed using a thermochromic liquid crystal-based convective heat transfer sensing system in which, liquid crystals change colour in response to the thermal footprints of a passing flow structure. Of the different vortical structures produced as a result of varying actuator operating and freestream conditions, the footprints of hairpin vortices and stretched vortex rings revealed a marked similarity with the oil flow pattern of a vortex pair interacting with the separation line on the cylinder hence suggesting that either of these structures was responsible in delaying separation. Conditions were established for the formation of the different synthetic jet structures in non-dimensional parameter space