1,200 research outputs found
Bayesian weighted K-Means clustering algorithm as applied to cotton trash measurement
Image segmentation is one of most difficult tasks in computer vision. It plays a critical role in object recognition of natural images. Unsupervised classification, or clustering, represents one promising approach for solving the image segmentation problem in typical application environments. The K-Means and Bayesian Learning algorithms are two well-known unsupervised classification methods. The K-Means approach is computationally efficient, but assumes imaging conditions which are unrealistic in many practical applications. While the Bayesian learning technique always produces a theoretically optimal segmentation result, the large, computational burden it requires is often unacceptable for many industrial tasks. A novel clustering algorithm, called Bayesian Weighted K-Means, is proposed in this thesis. Through simplification of the Bayesian learning approach\u27s decision-making process using cluster weights, the new technique is able to provide approximately optimal segmentation results while maintaining the computational efficiency generally associated with the K-means algorithm. The capabilities of this new algorithm are demonstrated using both synthetic images with controlled amounts of noise, and real color images of cotton lint contaminated with non-lint material
Correction of spherical single lens aberration using digital image processing for cellular phone camera
制度:新 ; 報告番号:甲3276号 ; 学位の種類:博士(工学) ; 授与年月日:2011/2/21 ; 早大学位記番号:新558
Chiral topological excitonic insulator in semiconductor quantum wells
We present a scheme to realize the chiral topological excitonic insulator in
semiconductor heterostructures which can be experimentally fabricated with a
coupled quantum well adjacent to twoferromagnetic insulating films. The
different mean-field chiral topological orders, which are due to the change in
the directions of the magnetization of the ferromagnetic films, can be
characterized by the TKNN numbers in the bulk system as well as by the winding
numbers of the gapless states in the edged system. Furthermore, we propose an
experimental scheme to detect the emergence of the chiral gapless edge state
and distinguish different chiral topological orders by measuring the thermal
conductance.Comment: 14 pages, 4 figure
Topological edge states and quantum Hall effect in the Haldane model
We study the topological edge states of the Haldane's graphene model with
zigzag/armchair lattice edges. The Harper equation for solving the energies of
the edge states is derived. The results show that there are two edge states in
the bulk energy gap, corresponding to the two zero points of the Bloch function
on the complex-energy Riemann surface. The edge-state energy loops move around
the hole of the Riemann surface in appropriate system parameter regimes. The
quantized Hall conductance can be expressed by the winding numbers of the edge
states, which reflects the topological feature of the Haldane model.Comment: 5 pages, 6 figure
Possible hard X-ray shortages in bursts from KS 1731-260 and 4U 1705-44
Aims: A hard X-ray shortage, implying the cooling of the corona, was observed
during bursts of IGR J17473-272, 4U 1636-536, Aql X-1, and GS 1826-238. Apart
from these four sources, we investigate here an atoll sample, in which the
number of bursts for each source is larger than 5, to explore the possible
additional hard X-ray shortage during {\it Rossi X-ray timing explorer (RXTE)}
era. Methods: According to the source catalog that shows type-I bursts, we
analyzed all the available pointing observations of these sources carried out
by the {\it RXTE} proportional counter array (PCA). We grouped and combined the
bursts according to their outburst states and searched for the possible hard
X-ray shortage while bursting. Results: We found that the island states of KS
1731-260 and 4U 1705-44 show a hard X-ray shortage at significant levels of 4.5
and 4.7 and a systematic time lag of s and
s with respect to the soft X-rays, respectively. While in their banana branches
and other sources, we did not find any consistent shortage.Comment: 5 pages, 4 figures, accepted by A&A as a research not
- …