246 research outputs found

    Unsupervised Deep Hashing for Large-scale Visual Search

    Full text link
    Learning based hashing plays a pivotal role in large-scale visual search. However, most existing hashing algorithms tend to learn shallow models that do not seek representative binary codes. In this paper, we propose a novel hashing approach based on unsupervised deep learning to hierarchically transform features into hash codes. Within the heterogeneous deep hashing framework, the autoencoder layers with specific constraints are considered to model the nonlinear mapping between features and binary codes. Then, a Restricted Boltzmann Machine (RBM) layer with constraints is utilized to reduce the dimension in the hamming space. Extensive experiments on the problem of visual search demonstrate the competitiveness of our proposed approach compared to state-of-the-art

    Kinship Verification from Videos using Spatio-Temporal Texture Features and Deep Learning

    Full text link
    Automatic kinship verification using facial images is a relatively new and challenging research problem in computer vision. It consists in automatically predicting whether two persons have a biological kin relation by examining their facial attributes. While most of the existing works extract shallow handcrafted features from still face images, we approach this problem from spatio-temporal point of view and explore the use of both shallow texture features and deep features for characterizing faces. Promising results, especially those of deep features, are obtained on the benchmark UvA-NEMO Smile database. Our extensive experiments also show the superiority of using videos over still images, hence pointing out the important role of facial dynamics in kinship verification. Furthermore, the fusion of the two types of features (i.e. shallow spatio-temporal texture features and deep features) shows significant performance improvements compared to state-of-the-art methods.Comment: 7 page

    Free vibration analysis of suspended super long span CFRP cables

    Get PDF
    The dynamic characteristics of an assumed isolated CFRP main cable are studied. The section area of the CFRP cable is determined for suspension bridge in different spans and sag-span ratios based on the principle of limit design at a given security coefficient. The Irvine parameter for suspension bridge with backstay and without backstay is calculated and a rule that Irvine parameter is linearly changed with span and sag ratio respectively is found. The analysis of frequency change with span shows that the first and third symmetric frequency is lager and less than the corresponding antisymmetric frequency respectively, but the second symmetric and antisymmetric frequencies are close to each other. The analysis on frequency and dimensionless frequency change with sag ratio show that for bridge with and without backstay the first and third order symmetric frequencies are larger and less than the corresponding antisymmetric frequencies respectively, but for a bridge without backstay the crossover phenomenon happens and the second symmetric mode changes from two to four internal nodes mode

    Modal analysis of the triple-tower twin-span suspension bridge in deck unit erection stage

    Get PDF
    Modal analysis of large span suspension bridge in different construction stages has to be carried out for the aerodynamic instability analysis. Based on the finite element (FE) model of a triple-tower twin-span (TTTS) suspension bridge in the completed stage, the FE models of the tower-cable-deck system corresponding to 0 %, 5 %, 10 %, 20 %, 30 %, and 40 % deck units erection stage are established respectively by a backward dismantling method. Then, the dynamic characteristics of each of the tower-cable-deck systems are analyzed to study the modal properties of TTTS suspension bridge in various deck erection stages. The results demonstrate that the natural frequencies of each erection stage are closely distributed in the low-order range. In the beginning of the deck units erection stage, the tower-cable-dominated modes are the primary modes and the deck-dominated modes come to next. Due to the strong interactions between deck unites and the cables, both the in-plane and out-of-plane vibrations of cables would excite the swing, lifting or torsional modes of the deck units. Both the in-plane and out-of-plane modes including in-phase and out-of-phase modes of the two main cables in the same span or symmetry and anti-symmetry modes of the neighboring-span cables as well as their corresponding combinations can be classified into groups. With more deck unites erected, the main girder is built up gradually, and thus the frequencies of deck-dominated mode would arise. The different frequency variations result in the modal crossover phenomena, which reflect the instability of the dynamic characteristics during the long deck erection period. At last, the aerodynamic stability of the suspension bridge is checked at each early erection stage, and a wind ropes application for the aerodynamic stability enhancement is investigated. The study of dynamic characteristics provides a reference for the wind-resistance analysis of the TTTS suspension bridge during the deck units erection stage
    • …
    corecore