356,404 research outputs found
Multitraining support vector machine for image retrieval
Relevance feedback (RF) schemes based on support vector machines (SVMs) have been widely used in content-based image retrieval (CBIR). However, the performance of SVM-based RF approaches is often poor when the number of labeled feedback samples is small. This is mainly due to 1) the SVM classifier being unstable for small-size training sets because its optimal hyper plane is too sensitive to the training examples; and 2) the kernel method being ineffective because the feature dimension is much greater than the size of the training samples. In this paper, we develop a new machine learning technique, multitraining SVM (MTSVM), which combines the merits of the cotraining technique and a random sampling method in the feature space. Based on the proposed MTSVM algorithm, the above two problems can be mitigated. Experiments are carried out on a large image set of some 20 000 images, and the preliminary results demonstrate that the developed method consistently improves the performance over conventional SVM-based RFs in terms of precision and standard deviation, which are used to evaluate the effectiveness and robustness of a RF algorithm, respectively
Recommended from our members
Integration, management and communication of heterogeneous design resources with WWW technologies
Recently, advanced information technologies have opened new pos-sibilities for collaborative designs. In this paper, a Web-based collaborative de-sign environment is proposed, where heterogeneous design applications can be integrated with a common interface, managed dynamically for publishing and searching, and communicated with each other for integrated multi-objective de-sign. The CORBA (Common Object Request Broker Architecture) is employed as an implementation tool to enable integration and communication of design application programs; and the XML (eXtensible Markup Language) is used as a common data descriptive language for data exchange between heterogeneous applications and for resource description and recording. This paper also intro-duces the implementation of the system and the encapsulating issues of existing legacy applications. At last, an example of gear design based on the system is il-lustrated to identify the methods and procedure developed by this research
Doping dependance of the spin resonance peak in bilayer high- superconductors
Motivated by a recent experiment on the bilayer
YCaBaCuO superconductor and based on a bilayer
model, we calculate the spin susceptibility at different doping densities in
the even and odd channels in a bilayer system. It is found that the intensity
of the resonance peak in the even channel is much weaker than that in the odd
one, with the resonance position being at a higher frequency. While this
difference decreases as the doping increases, and both the position and
amplitude of the resonance peaks in the two channels are very similar in the
deeply overdoped sample. Moreover, the resonance frequency in the odd channel
is found to be linear with the critical temperature , while the resonance
frequency increases as doping decreases in the even channel and tends to
saturate at the underdoped sample. We elaborate the results based on the Fermi
surface topology and the d-wave superconductivity.Comment: 6 pages, 5 figure
Concept Validation for Selective Heating and Press Hardening of Automotive Safety Components with Tailored Properties
© (2014) Trans Tech Publications, Switzerland.A new strategy termed selective heating and press hardening, for hot stamping of boron steel parts with tailored properties is proposed in this paper. Feasibility studies were carried out through a specially designed experimental programme. The main aim was to validate the strategy and demonstrate its potential for structural optimisation. In the work, a lab-scale demonstrator part was designed, and relevant manufacturing and property-assessment processes were defined. A heating technique and selective-heating rigs were designed to enable certain microstructural distributions in blanks to be obtained. A hot stamping tool set was designed for forming and quenching the parts. Demonstrator parts of full martensite phase, full initial phase, and differentially graded microstructures have been formed with high dimensional quality. Hardness testing and three point bending tests were conducted to assess the microstructure distribution and load bearing performance of the as-formed parts, respectively. The feasibility of the concept has been validated by the testing results
A propeller scenario for the gamma-ray emission of low-mass X-ray binaries: The case of XSS J12270-4859
XSS J12270-4859 is the only low mass X-ray binary (LMXB) with a proposed
persistent gamma-ray counterpart in the Fermi-LAT domain, 2FGL 1227.7-4853.
Here, we present the results of the analysis of recent INTEGRAL observations,
aimed at assessing the long-term variability of the hard X-ray emission, and
thus the stability of the accretion state. We confirm that the source behaves
as a persistent hard X-ray emitter between 2003 and 2012. We propose that XSS
J12270-4859 hosts a neutron star in a propeller state, a state we investigate
in detail, developing a theoretical model to reproduce the associated X-ray and
gamma-ray properties. This model can be understood as being of a more general
nature, representing a viable alternative by which LMXBs can appear as
gamma-ray sources. In particular, this may apply to the case of millisecond
pulsars performing a transition from a state powered by the rotation of their
magnetic field, to a state powered by matter in-fall, such as that recently
observed from the transitional pulsar PSR J1023+0038. While the surface
magnetic field of a typical NS in a LMXB is lower by more than four orders of
magnitude than the much more intense fields of neutron stars accompanying
high-mass binaries, the radius at which the matter in-flow is truncated in a
NS-LMXB system is much lower. The magnetic field at the magnetospheric
interface is then orders of magnitude larger at this interface, and as
consequence, so is the power to accelerate electrons. We demonstrate that the
cooling of the accelerated electron population takes place mainly through
synchrotron interaction with the magnetic field permeating the interface, and
through inverse Compton losses due to the interaction between the electrons and
the synchrotron photons they emit. We found that self-synchrotron Compton
processes can explain the high energy phenomenology of XSS J12270-4859.Comment: 12 pages, 3 figures, accepted for publication in MNRAS. References
update
Theory of the vortex matter transformations in high Tc superconductor YBCO
Flux line lattice in type II superconductors undergoes a transition into a
"disordered" phase like vortex liquid or vortex glass, due to thermal
fluctuations and random quenched disorder. We quantitatively describe the
competition between the thermal fluctuations and the disorder using the
Ginzburg -- Landau approach. The following T-H phase diagram of YBCO emerges.
There are just two distinct thermodynamical phases, the homogeneous and the
crystalline one, separated by a single first order transitions line. The line
however makes a wiggle near the experimentally claimed critical point at 12T.
The "critical point" is reinterpreted as a (noncritical) Kauzmann point in
which the latent heat vanishes and the line is parallel to the T axis. The
magnetization, the entropy and the specific heat discontinuities at melting
compare well with experiments.Comment: 4 pages 3 figure
Correlated Spectral and Temporal Variability in the High-Energy Emission from Blazars
Blazar flare data show energy-dependent lags and correlated variability
between optical/X-ray and GeV-TeV energies, and follow characteristic
trajectories when plotted in the spectral-index/flux plane. This behavior is
qualitatively explained if nonthermal electrons are injected over a finite time
interval in the comoving plasma frame and cool by radiative processes.
Numerical results are presented which show the importance of the effects of
synchrotron self-Compton cooling and plasmoid deceleration. The use of INTEGRAL
to advance our understanding of these systems is discussed.Comment: 8 pages, 5 figures, uses epsf.sty, rotate.sty Invited paper in "The
Extreme Universe," 3rd INTEGRAL Workshop, 14-18 September 1998, Taorimina,
Ital
- …