One of the main research tasks in community question answering (cQA) is finding the most relevant questions for a given new query, thereby providing useful knowledge for users. The straightforward approach is to capitalize on textual features, or a bag-of-words (BoW) representation, to conduct the matching process between queries and questions. However, these approaches have a lexical gap issue which means that, if lexicon matching fails, they cannot model the semantic meaning. In addition, latent semantic models, like latent semantic analysis (LSA), attempt to map queries to its corresponding semantically similar questions through a lower dimension representation. But alas, LSA is a shallow and linear model that cannot model highly non-linear correlations in cQA. Moreover, both BoW and semantic oriented solutions utilize a single dictionary to represent the query, question, and answer in the same feature space. However, the correlations between them, as we observe from data, imply that they lie in entirely different feature spaces. In light of these observations, this paper proposes a tri-modal deep belief network (tri-DBN) to extract a unified representation for the query, question, and answer, with the hypothesis that they locate in three different feature spaces. Besides, we compare the unified representation extracted by our model with other representations using the Yahoo! Answers queries on the dataset. Finally, Experimental results reveal that the proposed model captures semantic meaning both within and between queries, questions, and answers. In addition, the results also suggest that the joint representation extracted via the proposed method can improve the performance of cQA archives searching.

Seeding substrates with diamond nanocrystals has been considered to be a promising nondestructive pretreatment method for growth of diamond films. However, its application is strongly impeded by the segregation of diamond nanocrystals on substrates. In the present study, we suggest a very simple but effective seeding way ("sandwich" (SW) seeding way) to prevent nanocrystals from segregation. By the SW seeding way, the diamond nanocrystals can be nearly uniformly dispersed on Si substrates with the areal density of the order of 108cm-2. On the nano-seeded Si substrates the continuous and homogeneous diamond films can be successfully fabricated using a microwave plasma enhanced chemical-vapor-deposition (MPECVD) equipment. The cross-sectional transmission electron microscopy (TEM) images reveal that compare with the diamond films grown on the Si substrates pretreated by the conventional scratching method, the films deposited on the nano-seeded Si substrates present a much flatter interfacial structure, suggesting that the SW seeding way can effectively reduce the interface coarseness.

A type of carbon nanoform (carbon nanowalls: CNWs) has been successfully deposited on both Ni wafers and Ni wires using dc plasma chemical-vapor-deposition (CVD) method. Transmission electron microscopy (TEM) and Raman spectroscopy were used to characterize CNWs' microstructure. It is found that CNWs are well crystallized, and each CNW consists of several pieces of curved graphene sheets, presenting a quasi-two-dimensional geometry. The average length and width of CNWs are about 2-4µm, while their thickness is less than 7nm. Field emission measurement showed that such CNW films exhibited the excellent electron emission efficiency, comparable to the high-grade carbon nanotube (CNT) emitters. The threshold field defined as the field to obtained 1µA/cm2 is less than 1V/µm and the electrical field for 1mA/cm2 current density is only about 1.5V/µm. Moreover, the CNWs have stable emission behaviors, and we have successfully fabricated a kind of high-brightness lamps based on the CNW coated Ni wires.

This paper describes a broadband low phase noise VCO implemented in 0.13 µm CMOS process. A 1-bit switched varactor and a 4-bit capacitor array are adopted in cooperation with the automatic frequency calibration (AFC) circuit to lower the VCO tuning gain (KVCO), with a measured AFC time of 6 µs. Several noise reduction techniques are exploited to minimize the phase noise of the VCO. Measurement results show the VCO generates a high frequency range from 11.37 GHz to 14.8 GHz with a KVCO of less than 270 MHz/V. The prototype exhibits a phase noise of -114.6 dBc/Hz @ 1 MHz at 14.67 GHz carrier frequency and draws 10.5 mA current from a 1.2 V supply. The achieved figure-of-merits (FoM=-186.9dBc/Hz, FoMT=-195.3dBc/Hz) favorably compares with the state-of-the-art.