Knowledge-based Query Expansion in Real-Time Microblog Search

Since the length of microblog texts, such as tweets, is strictly limited to 140 characters, traditional Information Retrieval techniques suffer from the vocabulary mismatch problem severely and cannot yield good performance in the context of microblogosphere. To address this critical challenge, in this paper, we propose a new language modeling approach for microblog retrieval by inferring various types of context information. In particular, we expand the query using knowledge terms derived from Freebase so that the expanded one can better reflect users' search intent. Besides, in order to further satisfy users' real-time information need, we incorporate temporal evidences into the expansion method, which can boost recent tweets in the retrieval results with respect to a given topic. Experimental results on two official TREC Twitter corpora demonstrate the significant superiority of our approach over baseline methods.Comment: 9 pages, 9 figure

Two-step relaxations in metallic glasses during isothermal annealing

Isothermal annealing is a very useful strategy in modulating the properties and structures of metallic glasses, which has been regarded as a single relaxation progress. In this work, the enthalpy relaxation of Au-based metallic glasses are studied using a high-precision calorimetry. An intriguing transition from beta relaxation to alpha relaxation was confirmed during isothermal annealing. Energy landscape model is proposed to quantitatively explain how the relaxation modes transform. It is found that a small enthalpy decrease (about 0.8 kJ/mol) in initial state causes an extremely large increase (about 100 kJ/mol) in relaxation barrier, which is attributed to the enhanced cooperative atomic motion. These results open a gate for precisely understanding the role of different relaxation modes in modifying the properties of metallic glasses