9,068 research outputs found
Wigner's -matrix elements for - A Generating Function Approach
A generating function for the Wigner's -matrix elements of is
derived. From this an explicit expression for the individual matrix elements is
obtained in a closed form.Comment: RevTex 3.0, 22 pages, no figure
Residual stress development and evolution in two-phase crystalline material: a discrete dislocation study
Crystalline materials undergo heterogeneous deformation upon the application of external load, which results in the development of incompatible elastic strains in the material as soon as the load is removed. The presence of heterogeneous distribution of elastic strains in the absence of any form of external load results in the building up of stresses referred to as residual stresses. The heterogeneity of strain is attributed either to the presence of multiple phases or to the orientation gradients across the sample volume. This paper is an endeavour to model the presence of second phase in a two-dimensional discrete dislocation dynamics framework, which already contains constitutive rules to include three-dimensional mechanisms, such as line tension and dynamic junction formation. The model is used to investigate residual stress development in single crystals subjected to plane strain loading and then subsequently unloaded to study residual stresses. The dislocation accumulation around the second phase and its effect on the mechanical properties is studied. The orientation dependence of residual stresses as a function of the underlying defect substructure has also been explored. A variety of results are obtained. In particular, the development of stresses as a function of underlying defect substructure is also presented and found to depend upon the orientation of the crystal
Neutral Higgs boson pair production at the LC in the Noncommutative Standard Model
We study the Higgs boson pair production through collision in the
noncommutative(NC) extension of the standard model using the Seiberg-Witten
maps of this to the first order of the noncommutative parameter . This process is forbidden in the standard model with background
space-time being commutative. We find that the cross section of the pair
production of Higgs boson (of intermediate and heavy mass) at the future Linear
Collider(LC) can be quite significant for the NC scale lying in the
range TeV. Finally, using the direct experimental(LEP II, Tevatron
and global electro-weak fit) bound on Higgs mass, we obtain bounds on the NC
scale as 665 GeV GeV.Comment: 14 pages, 8 figure
Study of Ni and Zn doped CeOFeAs: Effect on the structural transition and specific heat capacity
We have systematically studied the substitution of nonmagnetic Zn and
magnetic Ni at iron sites in Ce based oxypnictide. The parent compound
(CeOFeAs) shows an anomaly in resistivity around 150 K due to structural
transition from tetragonal (space group: P4/nmm) to orthorhombic structure
(space group: Cmma). Substitution of Zn suppresses this anomaly to lower
temperature (~130 K) but Ni substitution does not show any anomaly around this
temperature and the compound behaves like a metal. Further, we find that non
magnetic (Zn) doping leads to higher impurity scattering as compared to
magnetic Ni doping. Similar to the resistivity measurement, the specific heat
shows another jump near 4 K for CeOFeAs. This is attributed to the ordering of
Ce3+ moments. This peak shifts to 3.8 K for Zn substituted compound and there
is no change in the ordering temperature in the Ni substituted CeOFeAs. These
peaks are broadened in applied magnetic field (5 T) and the calculated magnetic
entropy tends to saturate at the same value for 0 T and 5 T external magnetic
field.Comment: 16 pages Text+Fig
Texture Based Multifocus Image Fusion Using Interval Type 2 Fuzzy Logic
Multifocus image fusion is a process of fusing two or more images where region of focus in each image is different.  The objective is to obtain one image which contains the clear regions or in-focus regions of each image. Extracting the focused region in each image is a challenging task. Various techniques are available in literature to perform this task. Texture is one such feature which acts as a discriminating factor between focused and out-of-focus regions. Texture based image fusion has been used in our approach in combination with interval type 2 fuzzy logic and discrete wavelet transforms. Performance metrics obtained using this approach are better compared to other existing techniques. Gray Level Cooccurence Matrix (GLCM) method is used to extract the texture. Type 2 Sugeno fuzzy logic is used to combine the images. The fused image is compared with the reference image when it is available. It is also compared with the original images and performance metrics are computed and presented in this paper. Keywords: Discrete Wavelet Transform, Gray Level Cooccurence Matrix, Image Fusion, Multifocus Image, Type 2 Fuzzy Logic, Mamdani FLS, Sugeno FL
The SDSS-IV extended baryon oscillation spectroscopic survey: luminous red galaxy target selection
The Astrophysical Journal 224.2 (2016): 34 reproduced by permission of the AASWe describe the algorithm used to select the luminous red galaxy (LRG) sample for the extended Baryon Oscillation Spectroscopic Survey (eBOSS) of the Sloan Digital Sky Survey IV (SDSS-IV) using photometric data from both the SDSS and the Wide-field Infrared Survey Explorer. LRG targets are required to meet a set of color selection criteria and have z-band and i-band MODEL magnitudes z < 19.95 and 19.9 < i < 21.8, respectively. Our algorithm selects roughly 50 LRG targets per square degree, the great majority of which lie in the redshift range 0.6 < z < 1.0 (median redshift 0.71). We demonstrate that our methods are highly effective at eliminating stellar contamination and lower-redshift galaxies. We perform a number of tests using spectroscopic data from SDSS-III/BOSS ancillary programs to determine the redshift reliability of our target selection and its ability to meet the science requirements of eBOSS. The SDSS spectra are of high enough signal-to-noise ratio that at least ∼89% of the target sample yields secure redshift measurements. We also present tests of the uniformity and homogeneity of the sample, demonstrating that it should be clean enough for studies of the large-scale structure of the universe at higher redshifts than SDSS-III/BOSS LRGs reache
Unpolarized light in quantum optics
We present a new derivation of the unpolarized quantum states of light, whose
general form was first derived by Prakash and Chandra [Phys. Rev. A 4, 796
(1971)]. Our derivation makes use of some basic group theory, is
straightforward, and offers some new insights.Comment: 3 pages, REVTeX, presented at ICQO'200
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