Polarization singularity index determination by using a tilted lens

2021 ◽  
Vol 60 (12) ◽  
pp. 3266
Author(s):  
Baby Komal ◽  
S. Deepa ◽  
Sunil Kumar ◽  
P. Senthilkumaran
Keyword(s):  
Singularity Index

scholarly journals A novel iterative approach for mapping local singularities from geochemical data

2007 ◽  
Vol 14 (3) ◽  
pp. 317-324 ◽  
Author(s):  
◽  
◽  
◽  
Keyword(s):  
Large Scale ◽  
Mineral Exploration ◽  
Singularity Analysis ◽  
Geochemical Data ◽  
Iterative Approach ◽  
Scale Invariant ◽  
Singularity Index ◽  
Parameter Estimations ◽  
Singular Functions ◽  
Local Singularity

Abstract. There are many phenomena in nature, such as earthquakes, landslides, floods, and large-scale mineralization that are characterized by singular functions exhibiting scale invariant properties. A local singularity analysis based on multifractal modeling was developed for detection of local anomalies for mineral exploration. An iterative approach is proposed in the current paper for improvement of parameter estimations involved in the local singularity analysis. The advantage of this new approach is demonstrated with de Wijs's zinc data from a sphalerite-quartz vein near Pulacayo in Bolivia. The semivariogram method was used to illustrate the differences between the raw data and the estimated data by the new algorithm. It has been shown that the outcome of the local singularity analysis consists of two components: singularity component characterized by local singularity index and the non-singular component by prefractal parameter.

Specimen Design for IFSS Measurement in Fiber Pullout Test

2006 ◽  
Vol 312 ◽  
pp. 149-154 ◽  
Author(s):  
Ying Dai ◽  
Xing Ji ◽  
Lin Ye ◽  
Yiu Wing Mai
Keyword(s):  
Stress Field ◽  
Critical Angle ◽  
Wedge Angle ◽  
Stress Singularity ◽  
Pullout Test ◽  
Matrix System ◽  
Interface Shear ◽  
Singularity Index ◽  
Characteristic Determinant ◽  
Fiber Matrix

Since stress singularity was found at the interface end in current specimen of pullout test, interface shear strength (IFSS) obtained from the tests loses its rationality [2]. But a useful conclusion [2] is that when the wedge angle of the matrix is less than a critical angle, the singularity of stress field at the interface end of the specimen in micro-debond test nearly disappears. Following this conclusion, a conic specimen shown in Fig. 1 is presented, in which the wedge angle of the specimen is designed to be less than a critical angle in order to prevent the singular stress field occurred at the interface end. The conic specimen is designed for pullout test to avoid disadvantages inherent in the micro-debond test [3]. An axisymmetric model of fiber/matrix system with arbitrary wedge angles at the interface end is used for the determination of critical wedge angle. With the aid of asymptotic analysis and variable separation, eigenvalue, λ, could be determined by a characteristic determinant. For a given fiber-matrix system, a curve representing the relationship between the stress singularity index and wedge angle could be obtained by solving the characteristic determinant. We define the critical wedge angle, θcr, as the corresponding singularity index of – 0.005. The design of a conic pullout specimen is also discussed. FEM analysis is adopted to calculate the distribution of interfacial stresses near the interface end with different wedge angle. The results verify the rationality of the principle of the design of conic pullout specimen for IFSS measurement.

scholarly journals Sharp focusing of beams with V-point polarization singularities

2021 ◽  
Vol 5 (45) ◽  
pp. 643-653
Author(s):  
V.V. Kotlyar ◽  
A.G. Nalimov ◽  
S.S. Stafeev ◽  
A.A. Kovalev
Keyword(s):  
Intensity Distribution ◽  
Linear Polarization ◽  
Light Field ◽  
Focal Spot ◽  
Polarization Direction ◽  
Intensity Pattern ◽  
Singularity Index ◽  
Local Maxima ◽  
Sharp Focus ◽  
Sharp Focusing

It is theoretically and numerically shown that when tightly focusing an n-th order vector light field that has the central V-point (at which the linear polarization direction is undetermined), the polarization singularity index n, and a "flower"-shaped intensity pattern with 2(n-1) lobes it forms a transverse intensity distribution with 2(n-1) local maxima. At the same time, a vector light field with the polarization singularity index -n, which has the form of a "web" with 2(n+1) cells generates at the sharp focus a transverse intensity distribution with 2(n+1) local maxima. In the focal spot, either 2(n-1) or 2(n+1) V-point polarization singularities with alternating indices +1 or -1 are formed at the intensity zero.

scholarly journals Noise Analysis of a New Singularity Index

2013 ◽  
Vol 61 (24) ◽  
pp. 6150-6163 ◽  
Author(s):  
Gautam S. Muralidhar ◽  
Alan C. Bovik ◽  
Mia K. Markey
Keyword(s):  
Noise Analysis ◽  
Singularity Index

scholarly journals Mapping local singularities using magnetic data to investigate the volcanic rocks of the Qikou depression, Dagang oilfield, eastern China

2013 ◽  
Vol 20 (4) ◽  
pp. 501-511 ◽  
Author(s):  
G. Chen ◽  
Q. Cheng ◽  
T. Liu ◽  
Y. Yang
Keyword(s):  
Oil And Gas ◽  
Structural Characteristics ◽  
Eastern China ◽  
Volcanic Rocks ◽  
Magnetic Anomalies ◽  
Seismic Survey ◽  
Magnetic Data ◽  
Mapping Technique ◽  
Rock Density ◽  
Singularity Index

Abstract. The spatial structural characteristics of geological anomaly, including singularity and self-similarity, can be analysed using fractal or multifractal modelling. Here we apply the multifractal methods to potential fields to demonstrate that singularities can characterise geological bodies, including rock density and magnetic susceptibility. In addition to enhancing weak gravity and magnetic anomalies with respect to either strong or weak background levels, the local singularity index (α ≈ 2) can be used to delineate the edges of geological bodies. Two models were established to evaluate the effectiveness of mapping singularities for extracting weak anomalies and delineating edges of buried geological bodies. The Qikou depression of the Dagang oilfield in eastern China has been chosen as a study area for demonstrating the extraction of weak anomalies of volcanic rocks, using the singularity mapping technique to analyse complex magnetic anomalies caused by complex geological background. The results have shown that the singularities of magnetic data mapped in the paper are associated with buried volcanic rocks, which have been verified by both drilling and seismic survey, and the S–N and E–W faults in the region. The targets delineated for deeply seated faults and volcanic rocks in the Qikou depression should be further investigated for the potential application in undiscovered oil and gas reservoirs exploration.

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