Identification of the dominant diffusing species in silicide formation

Implanted noble gas atoms of Xe have been used as diffusion markers in the growth study of three silicides: Ni2Si, VSi2, and TiSi2. Backscattering of MeV He has been used to determine the displacement of the markers. We found that while Si atoms predominate the diffusion in VSi2 and TiSi2, Ni atoms are the faster moving species in Ni2Si

Formation of diluted III–V nitride thin films by N ion implantation

iluted III–Nₓ–V₁ˍₓ alloys were successfully synthesized by nitrogen implantation into GaAs,InP, and AlyGa1−yAs. In all three cases the fundamental band-gap energy for the ion beam synthesized III–Nₓ–V₁ˍₓ alloys was found to decrease with increasing N implantation dose in a manner similar to that observed in epitaxially grownGaNₓAs1−x and InNₓP₁ˍₓalloys. In GaNₓAs₁ˍₓ the highest value of x (fraction of “active” substitutional N on As sublattice) achieved was 0.006. It was observed that NAs is thermally unstable at temperatures higher than 850 °C. The highest value of x achieved in InNₓP₁ˍₓ was higher, 0.012, and the NP was found to be stable to at least 850 °C. In addition, the N activation efficiency in implantedInNₓP₁ˍₓ was at least a factor of 2 higher than that in GaNₓAs₁ˍₓ under similar processing conditions. AlyGa1−yNₓAs₁ˍₓ had not been made previously by epitaxial techniques. N implantation was successful in producing AlyGa1−yNₓAs₁ˍₓalloys. Notably, the band gap of these alloys remains direct, even above the value of y (y>0.44) where the band gap of the host material is indirect.This work was supported by the ‘‘Photovoltaic Materials Focus Area’’ in the DOE Center of Excellence for the Synthesis and Processing of Advanced Materials, Office of Science, Office of Basic Energy Sciences, Division of Materials Sciences under U.S. Department of Energy Contract No. DE-ACO3-76SF00098. The work at UCSD was partially supported by Midwest Research Institute under subcontractor No. AAD-9-18668-7 from NREL

Binary Nonlinearization of Lax pairs of Kaup-Newell Soliton Hierarchy

Kaup-Newell soliton hierarchy is derived from a kind of Lax pairs different from the original ones. Binary nonlinearization procedure corresponding to the Bargmann symmetry constraint is carried out for those Lax pairs. The proposed Lax pairs together with adjoint Lax pairs are constrained as a hierarchy of commutative, finite dimensional integrable Hamiltonian systems in the Liouville sense, which also provides us with new examples of finite dimensional integrable Hamiltonian systems. A sort of involutive solutions to the Kaup-Newell hierarchy are exhibited through the obtained finite dimensional integrable systems and the general involutive system engendered by binary nonlinearization is reduced to a specific involutive system generated by mono-nonlinearization.Comment: 15 pages, plain+ams tex, to be published in Il Nuovo Cimento

Meso-scale modelling of compressive fracture in concrete with irregularly shaped aggregates

This paper presents a meso-scale modelling framework to investigate the fracture process in concrete subjected to uniaxial and biaxial compression accounting for its mesostructural characteristics. 3D mesostructure of concrete consisting of coarse aggregates, mortar and interfacial transition zone between them was developed using an in-house code based on the Voronoi tessellation and splining method, which enables to generate the realistic-look aggregates with controllable structural features such as content, location, size and shape. Based on the generated 3D mesostructure, the concrete damage plasticity approach was employed to simulate the compressive fracture behaviour of concrete in terms of crack morphology and stress-strain response against the shape parameters of aggregate. Results indicate that the shape of aggregate has a negligible effect on compressive strength of concrete, which is highly associated with the random location and size distribution of aggregate. The aggregate irregularity has a significant influence on crack initiation and growth of concrete

LCCT: a semisupervised model for sentiment classification

Conference Theme: Human Language TechnologiesAnalyzing public opinions towards products, services and social events is an important but challenging task. An accurate sentiment analyzer should take both lexicon-level information and corpus-level information into account. It also needs to exploit the domain-specific knowledge and utilize the common knowledge shared across domains. In addition, we want the algorithm being able to deal with missing labels and learning from incomplete sentiment lexicons. This paper presents a LCCT (Lexicon-based and Corpus-based, Co-Training) model for semi-supervised sentiment classification. The proposed method combines the idea of lexicon-based learning and corpus-based learning in a unified co-training framework. It is capable of incorporating both domain-specific and domain-independent knowledge. Extensive experiments show that it achieves very competitive classification accuracy, even with a small portion of labeled data. Comparing to state-of-the-art sentiment classification methods, the LCCT approach exhibits significantly better performances on a variety of datasets in both English and Chinese. © 2015 Association for Computational Linguisticspublished_or_final_versio