A new statistical strategy for pooling: ELI

Doing exhaustive relevance judgments is one of the most challenging tasks in the construction process of an IR test collection, especially when the collection is composed of millions of documents. Pooling (or system pooling), which is basically a method for selecting documents to assess, is a solution to overcome this challenge. In this paper, to form such an assessment pool, a new, ranked-based document selection criterion, called the expected level of importance (ELI), is introduced. The results of the experiments performed, using TREC 5, 6, 7, and 8 data, showed that by using a pool in which the documents are sorted in the decreasing order of their calculated ELI scores, relevance judgments can efficiently be made by minimal human effort, while maintaining the size and the effectiveness of the resulting test collection. The criterion we propose can directly be adapted to the traditional TREC pooling practice in favor of efficiency, with no additional cost.     

Drillability studies on the rotary blasthole drilling of lignite overburden series

ABSTRACT

This paper describes the results of drillability studies on rotary blasthole drillings for lignite overburden series at open pit lignite mines in Turkey. Field and laboratory studies are carried out at 96 different locations of 16 lignite mines to determine formation properties and to obtain drill performance data such as penetration rate, thrust, RPM. The obtained data analysed and the relation between some rock properties such as uniaxial compressive strength, cohesion, tensile strength, unit weight, impedance and penetration rate have been established. Among these rock properties, uniaxial compressive strength has been selected as a single parameter giving the highest correlation coefficient and to produce simple and practical relation. Finally thrust and RPM requirements are investigated and a chart based on uniaxial compressive strength is proposed to estimate thrust, RPM and corresponding penetration rate.