18,433 research outputs found

    Ferromagnetism in 2p Light Element-Doped II-oxide and III-nitride Semiconductors

    Full text link
    II-oxide and III-nitride semiconductors doped by nonmagnetic 2p light elements are investigated as potential dilute magnetic semiconductors (DMS). Based on our first-principle calculations, nitrogen doped ZnO, carbon doped ZnO, and carbon doped AlN are predicted to be ferromagnetic. The ferromagnetism of such DMS materials can be attributed to a p-d exchange-like p-p coupling interaction which is derived from the similar symmetry and wave function between the impurity (p-like t_2) and valence (p) states. We also propose a co-doping mechanism, using beryllium and nitrogen as dopants in ZnO, to enhance the ferromagnetic coupling and to increase the solubility and activity

    From Traditional to Modern : Domain Adaptation for Action Classification in Short Social Video Clips

    Full text link
    Short internet video clips like vines present a significantly wild distribution compared to traditional video datasets. In this paper, we focus on the problem of unsupervised action classification in wild vines using traditional labeled datasets. To this end, we use a data augmentation based simple domain adaptation strategy. We utilise semantic word2vec space as a common subspace to embed video features from both, labeled source domain and unlablled target domain. Our method incrementally augments the labeled source with target samples and iteratively modifies the embedding function to bring the source and target distributions together. Additionally, we utilise a multi-modal representation that incorporates noisy semantic information available in form of hash-tags. We show the effectiveness of this simple adaptation technique on a test set of vines and achieve notable improvements in performance.Comment: 9 pages, GCPR, 201

    Simulation and forming mechanism analysis of multi-pass spinning process of deep cylinder parts

    Get PDF
    In this paper, the forming mechanism of 3103 aluminum alloy forming deep cylinder part under ten passes spinning is studied. The forming process of each step is simulated by finite element method. The distribution characteristics of equivalent stress field and strain field in forming were analyzed in detail. The influence of feed ratio on spinning force is obtained. By measuring the thickness and circularity of the final forming deep cylinder part, the final forming effect of multi-pass spinning is obtained

    Simulation and forming mechanism analysis of multi-pass spinning process of deep cylinder parts

    Get PDF
    In this paper, the forming mechanism of 3103 aluminum alloy forming deep cylinder part under ten passes spinning is studied. The forming process of each step is simulated by finite element method. The distribution characteristics of equivalent stress field and strain field in forming were analyzed in detail. The influence of feed ratio on spinning force is obtained. By measuring the thickness and circularity of the final forming deep cylinder part, the final forming effect of multi-pass spinning is obtained

    Spatial distribution and temporal variations of atmospheric sulfur deposition in Northern China: insights into the potential acidification risks

    Get PDF
    Atmospheric sulfur (S) deposition via precipitation, particles and gases was investigated at ten sites in Northern China. Measurements were performed continuously between December 2007 and November 2010. The total S deposition flux in the target area ranged from 35.0 to 100.7 kg S ha<sup>−1</sup> yr<sup>−1</sup>, noticeably higher than the values documented in Europe, North America, and East Asia. The ten-site, 3-yr average total S deposition was 64.8 kg S ha<sup>−1</sup> yr<sup>−1</sup>, with 68% attributed to dry deposition (mainly SO<sub>2</sub>) and the rest to wet deposition. Consequently, the spatial distribution of the total flux was consistent to that of dry deposition, that is, higher values were observed at industrial and urban sites than at agricultural and rural sites. However, the seasonal variation in the total S deposition was not obvious across the entire year because of opposite seasonal trends in wet and dry deposition. It was found that the wet deposition, without significant spatial and interannual differences, was influenced by the volume of precipitation, the air-column concentrations of S compounds and in-cloud scavenging. Similar to the wet deposition, the dry-deposited sulfate was also less dependent on the surface concentration. Nevertheless, the regional differences in SO<sub>2</sub> dry deposition were mostly explained by the ambient concentration, which is closely associated with local emissions. As expected, the spatial pattern of total S deposition resembled that of the emission inventory, indicating the dramatic anthropogenic imprints on the regional S budget. Although at most of the study sites the "acid equivalents" deposition of S was comparable to that of nitrogen (N), the importance of S in the acidification risks was more pronounced at the industrial sites. The ten-site, 3-yr mean total "acid equivalents" deposition of S and N was estimated to be 8.4 (range: 4.2–11.6) keq ha<sup>−1</sup> yr<sup>−1</sup>, which exceeds the critical loads for natural ecosystems in Northern China. Taking these findings and our previous studies together, a multi-pollutant perspective and joint mitigation strategies to abate SO<sub>2</sub> and NH<sub>3</sub> simultaneously in the target area are recommended to protect natural ecosystems from excess acid deposition
    corecore