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    Vein pattern verification and identification based on local geometric invariants constructed from minutia points and augmented with barcoded local feature
    (2020-05-01)
    Pititheeraphab, Yutthana
    ;
    Thongpance, Nuntachai
    ;
    Aoyama, Hisayuki
    ;
    Pintavirooj, Chuchart
    This paper presents the development of a hybrid feature-dorsal hand vein and dorsal geometry-modality for human recognition. Our proposed hybrid feature extraction method exploits two types of features: dorsal hand geometric-related and local vein pattern. Using geometric affine invariants, the peg-free system extracts minutia points and vein termination and bifurcation and constructs a set of geometric invariants, which are then used to establish the correspondence between two sets of minutiae-one for the query vein image and the other for the reference vein image. When the correspondence is established, geometric transformation parameters are computed to align the query with the reference image. Once aligned, hybrid features are extracted for identification. In this study, the algorithm was tested on a database of 140 subjects, in which ten different dorsal hand geometric-related images were taken for each individual, and yielded the promising results. In this regard, we have achieved an equal error rate (EER) of 0.243%, indicating that our method is feasible and effective for dorsal vein recognition with high accuracy. This hierarchical scheme significantly improves the performance of personal verification and/or identification.
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    Contactless silicon-based multi-dimensional Hall sensor with simultaneous magnetic sensing and omni-rotational angle measurement
    (2019-01-01)
    Kaewjumras, Yongyut
    ;
    Prabket, Jirawat
    ;
    Titiroongruang, Wisut
    ;
    Niemcharoen, Surasak
    This experimental research proposes a contactless silicon-based two-dimensional (2D) Hall sensor capable of simultaneous parallel- and perpendicular-directional magnetic sensing, with a 360° angle measurement. The Hall sensor was of non-symmetrical five-ohmic contact configuration (C1 – C5). In the study, experiments were carried out in three stages. In the first-stage experiment, the current (I) and voltage (V) of the 2D Hall sensor were determined under three schemes: schemes A (C1&C2), B (C2&C5), and C (C3&C4). In the second-stage experiment, the parallel and perpendicular absolute sensitivities of the 2D sensor were examined. Considering the discrepancy between the parallel and perpendicular absolute sensitivities, signal conditioning circuitry was incorporated into the sensor system to compensate, and the rotational angles measured in the final-stage experiment. The results revealed that the I-V curves were dominantly linear, corresponding to Ohm’s law. However, the parallel and perpendicular absolute sensitivities were low and unequal. Thus, signal conditioning circuitry was incorporated into the system to address the discrepancy and improve the performance. Importantly, the 2D Hall sensor exhibited a mere ±3<sup>o</sup> discrepancy between the measured and reference rotational angles, given the magnetic flux density of 1000 G, with the hysteresis error of 2.8%. In essence, the proposed contactless silicon-based 2D Hall sensor possesses high potential for high-precision industrial applications.
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    The modification of yaw sensor for length standard calibration system
    (2017-12-13)
    Tipsuwanporn, Vittaya
    ;
    Chinchusak, Wanchai
    ;
    Numsomran, Arjin
    Yaw error measurements using a yaw sensor have been carried out to determine the characteristics of yaw errors and analyze the behaviors of the structural guide. The modification of yaw sensor design is necessary to improve the yaw error measurement. The contactless of a magnetic levitation technique that is supported a load of magnetic bearing. It is more suitable for reduction of yaw measurement error. This paper presents the new design of yaw sensor for the application that would be improved both the measurement error and repeatability. Those are measurement error and repeatability approximately minimized to 36 arcsec and less than 15 arcsec respectively, with the measurement uncertainty is 28.5 arcsec, at the confident level 95%.