655 research outputs found
Face Recognition using Fused Diagonal and Matrix Features
Face recognition with less information availability in terms of the number of image samples is a challenging task A simple and efficient method for face recognition is proposed in this paper to address small sample size problem and rotation variation of input images The robert s operator is used as edge detection method to elicit borders to crop the facial part and then all cropped images are resized to a uniform 50 50 size to complete the preprocessing step Preprocessed test images are rotated in different angles to check the robustness of proposed algorithm All preprocessed images are partitioned into one hundred 5 5 equal size parts The matrix 2-norm infinite norm trace and rank are elicited for each of 5 5 part and respectively averaged to yield on hundred matrix features Another one hundred diagonal features are extracted by applying a 3 3 mask on each image Final one hundred features are obtained by fusing averaged matrix and diogonal features Euclidian distance measure is used for comparision of database and query image features The results are comparitively better on three publically availabe datasets compared to existing method
Detonation driven shock wave interactions with perforated plates
The study of detonations and their interactions is vital for the understanding of the high-speed flow physics involved and the ultimate goal of controlling their detrimental effects. However, producing safe and repeatable detonations within the laboratory can be quite challenging, leading to the use of computational studies which ultimately require experimental data for their validation. The objective of this study is to examine the induced flow field from the interaction of a shock front and accompanying products of combustion, produced from the detonation taking place within a non-electrical tube lined with explosive material, with porous plates with varying porosities, 0.7–9.7%. State of the art high-speed schlieren photography alongside high-resolution pressure measurements is used to visualise the induced flow field and examine the attenuation effects which occur at different porosities. The detonation tube is placed at different distances from the plates' surface, 0–30 mm, and the pressure at the rear of the plate is recorded and compared. The results indicate that depending on the level of porosity and the Mach number of the precursor shock front secondary reflected and transmitted shock waves are formed through the coalescence of compression waves. With reduced porosity, the plates act almost as a solid surface, therefore the shock propagates faster along its surface
Spin-filtered Edge States with an Electrically Tunable Gap in a Two-Dimensional Topological Crystalline Insulator
Three-dimensional topological crystalline insulators were recently predicted
and observed in the SnTe class of IV-VI semiconductors, which host metallic
surface states protected by crystal symmetries. In this work, we study thin
films of these materials and expose their potential for device applications. We
demonstrate that thin films of SnTe and Pb(1-x)Sn(x)Se(Te) grown along the
(001) direction are topologically nontrivial in a wide range of film thickness
and carry conducting spin-filtered edge states that are protected by the (001)
mirror symmetry via a topological invariant. Application of an electric field
perpendicular to the film will break the mirror symmetry and generate a band
gap in these edge states. This functionality motivates us to propose a novel
topological transistor device, in which charge and spin transport are maximally
entangled and simultaneously controlled by an electric field. The high on/off
operation speed and coupling of spin and charge in such a device may lead to
electronic and spintronic applications for topological crystalline insulators.Comment: 6 pages, 5 figures, minor changes made, accepted to Nature Material
Unconventional Planar Hall Effect in Exchange-Coupled Topological Insulator-Ferromagnetic Insulator Heterostructures
The Dirac electrons occupying the surface states (SSs) of topological
insulators (TIs) have been predicted to exhibit many exciting magneto-transport
phenomena. Here we report on the first experimental observation of an
unconventional planar Hall effect (PHE) and an electrically gate-tunable
hysteretic planar magnetoresistance (PMR) in EuS/TI heterostructures, in which
EuS is a ferromagnetic insulator (FMI) with an in-plane magnetization. In such
exchange-coupled FMI/TI heterostructures, we find a significant (suppressed)
PHE when the in-plane magnetic field is parallel (perpendicular) to the
electric current. This behavior differs from previous observations of the PHE
in ferromagnets and semiconductors. Furthermore, as the thickness of the 3D TI
films is reduced into the 2D limit, in which the Dirac SSs develop a
hybridization gap, we find a suppression of the PHE around the charge neutral
point indicating the vital role of Dirac SSs in this phenomenon. To explain our
findings, we outline a symmetry argument that excludes linear-Hall mechanisms
and suggest two possible non-linear Hall mechanisms that can account for all
the essential qualitative features in our observations.Comment: 17 pages, 4 figures, accepted by Phys. Rev.
DBC based Face Recognition using DWT
The applications using face biometric has proved its reliability in last
decade. In this paper, we propose DBC based Face Recognition using DWT (DBC-
FR) model. The Poly-U Near Infra Red (NIR) database images are scanned and
cropped to get only the face part in pre-processing. The face part is resized
to 100*100 and DWT is applied to derive LL, LH, HL and HH subbands. The LL
subband of size 50*50 is converted into 100 cells with 5*5 dimention of each
cell. The Directional Binary Code (DBC) is applied on each 5*5 cell to derive
100 features. The Euclidian distance measure is used to compare the features of
test image and database images. The proposed algorithm render better percentage
recognition rate compared to the existing algorithm.Comment: 15 pages,9 figures, 4 table
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On the temporal analysis of acoustic waves using schlieren imaging
The primary objective of the present study was to develop a quantitative schlieren-imaging technique that can be used to study the dynamics of instability waves. The technique was initially validated by optically capturing a controlled acoustic wave generated by a compression driver and excellent agreement was obtained with microphone measurements. An underexpanded jet was considered as an ideal test case due to the complexity and multitude of instability mechanism. Further analysis of the underexpanded jet demonstrated that this technique can be used to capture the very high frequency mode related to the phenomenon of screech
Zero-field dissipationless chiral edge transport and the nature of dissipation in the quantum anomalous Hall state
The quantum anomalous Hall (QAH) effect is predicted to possess, at zero
magnetic field, chiral edge channels that conduct spin polarized current
without dissipation. While edge channels have been observed in previous
experimental studies of the QAH effect, their dissipationless nature at a zero
magnetic field has not been convincingly demonstrated. By a comprehensive
experimental study of the gate and temperature dependences of local and
nonlocal magnetoresistance, we unambiguously establish the dissipationless edge
transport. By studying the onset of dissipation, we also identify the origin of
dissipative channels and clarify the surprising observation that the critical
temperature of the QAH effect is two orders of magnitude smaller than the Curie
temperature of ferromagnetism.Comment: main text+supporting materials. This is the accepted version for PRL.
Comments are welcom
Gaint cell tumour of phalynx: have you seen it?
Giant cell tumors are rarely seen in the foot. Only 1-2% cases of GCT occur in the foot. They can cause a significant amount of pain and deformity due to their aggressive and recurrent nature whenever it occurs in foot. We present an unusual case of a giant cell tumor of proximal phalynx of middle toe of left foot. 26 year old male came with complaints of pain and swelling over the middle toe of left foot since 6 months. Clinical and radiological features showed features consistent with GCT. Foot Function Index revealed a) Pain scale: 29 / 50 = 58%, b) Disability scale: 56 / 90 = 62%, c) Activity limitation scale: 8 / 30 = 27%. Authors performed enbloc resection with ray amputation of 3rd toe. Histopathological examination of excised specimen revealed classic findings of mononuclear cells with interspersed fibro-collagenous strands and numerous multinucleated osteoclast-like giant cells which confirmed our diagnosis. Patient was serially followed up and at 6 months followup, there were no signs of recurrence with markedly improved foot function index
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