4,250 research outputs found
Less is More: Micro-expression Recognition from Video using Apex Frame
Despite recent interest and advances in facial micro-expression research,
there is still plenty room for improvement in terms of micro-expression
recognition. Conventional feature extraction approaches for micro-expression
video consider either the whole video sequence or a part of it, for
representation. However, with the high-speed video capture of micro-expressions
(100-200 fps), are all frames necessary to provide a sufficiently meaningful
representation? Is the luxury of data a bane to accurate recognition? A novel
proposition is presented in this paper, whereby we utilize only two images per
video: the apex frame and the onset frame. The apex frame of a video contains
the highest intensity of expression changes among all frames, while the onset
is the perfect choice of a reference frame with neutral expression. A new
feature extractor, Bi-Weighted Oriented Optical Flow (Bi-WOOF) is proposed to
encode essential expressiveness of the apex frame. We evaluated the proposed
method on five micro-expression databases: CAS(ME), CASME II, SMIC-HS,
SMIC-NIR and SMIC-VIS. Our experiments lend credence to our hypothesis, with
our proposed technique achieving a state-of-the-art F1-score recognition
performance of 61% and 62% in the high frame rate CASME II and SMIC-HS
databases respectively.Comment: 14 pages double-column, author affiliations updated, acknowledgment
of grant support adde
Shockley-Ramo theorem and long-range photocurrent response in gapless materials
Scanning photocurrent maps of gapless materials, such as graphene, often
exhibit complex patterns of hot spots positioned far from current-collecting
contacts. We develop a general framework that helps to explain the unusual
features of the observed patterns, such as the directional effect and the
global character of photoresponse. We show that such a response is captured by
a simple Shockley-Ramo-type approach. We examine specific examples and show
that the photoresponse patterns can serve as a powerful tool to extract
information about symmetry breaking, inhomogeneity, chirality, and other local
characteristics of the system.Comment: 7 pgs, 3 fg
Quantum feedback control and classical control theory
We introduce and discuss the problem of quantum feedback control in the context of established formulations of classical control theory, examining conceptual analogies and essential differences. We describe the application of state-observer-based control laws, familiar in classical control theory, to quantum systems and apply our methods to the particular case of switching the state of a particle in a double-well potential
Sacrificing Accuracy for Reduced Computation: Cascaded Inference Based on Softmax Confidence
We study the tradeoff between computational effort and accuracy in a cascade
of deep neural networks. During inference, early termination in the cascade is
controlled by confidence levels derived directly from the softmax outputs of
intermediate classifiers. The advantage of early termination is that
classification is performed using less computation, thus adjusting the
computational effort to the complexity of the input. Moreover, dynamic
modification of confidence thresholds allow one to trade accuracy for
computational effort without requiring retraining. Basing of early termination
on softmax classifier outputs is justified by experimentation that demonstrates
an almost linear relation between confidence levels in intermediate classifiers
and accuracy. Our experimentation with architectures based on ResNet obtained
the following results. (i) A speedup of 1.5 that sacrifices 1.4% accuracy with
respect to the CIFAR-10 test set. (ii) A speedup of 1.19 that sacrifices 0.7%
accuracy with respect to the CIFAR-100 test set. (iii) A speedup of 2.16 that
sacrifices 1.4% accuracy with respect to the SVHN test set
The impacts of surface conditions on the vapor-liquid-solid growth of germanium nanowires on Si (100) substrate
The impacts of surface conditions on the growth of Ge nanowires on a Si (100) substrate are discussed in detail. On SiO2-terminated Si substrates, high-density Ge nanowires can be easily grown. However, on H-terminated Si substrates, growing Ge nanowires is more complex. The silicon migration and the formation of a native SiO2 overlayer on a catalyst surface retard the growth of Ge nanowires. After removing this overlayer in the HF solution, high-density and well-ordered Ge nanowires are grown. Ge nanowires cross vertically and form two sets of parallel nanowires. It is found that nanowires grew along ?110? direction
Further investigation of a contactless patient-electrode interface of an Electrical Impedance Mammography system
The Sussex Mk4 Electrical Impedance Mammography (EIM) system is a novel instrument, designed for the detection of early breast cancer, based upon Electrical Impedance Tomography (EIT). Many innovations in the field have been incorporated in the design improving both signal distribution and response. This paper investigates the behaviour of the contactless patient-electrode interface. The interface was studied in detail using phantom and healthy volunteer, in-vivo, data. Our findings show the necessity for the careful design of electrode enclosure so that the response of the system is not affected by the unpredictable positioning of the breast; it closely mimics those conditions seen when using the phantom. The paper includes a number of possible designs and their individual characteristics. In addition an explanation on the unanticipated effects and solutions for such are described. © 2010 IOP Publishing Ltd
Band Offsets at Semiconductor-Oxide Interfaces from Hybrid Density Functional Calculations
Band offsets at semiconductor-oxide interfaces are determined through a
scheme based on hybrid density functionals, which incorporate a fraction
of Hartree-Fock exchange. For each bulk component, the fraction
is tuned to reproduce the experimental band gap, and the conduction
and valence band edges are then located with respect to a reference level. The
lineup of the bulk reference levels is determined through an interface
calculation, and shown to be almost independent of the fraction .
Application of this scheme to the Si-SiO, SiC-SiO, and Si-HfO
interfaces yields excellent agreement with experiment.Comment: 4 pages, 4 figure
- …