Hotspot Detection Using Ranked Set Sampling

One of the most preferential and critical needs of 21st century is the Geoinformatics of geospatial and spatio-temporal hotspot detection and prioritization. A declared need is around for statistical geoinformatics and software infrastructure development. The declared need may be for monitoring, etiology, early warning, or sustainable management. The responsible factors may be natural, accidental or intentional.The society in which we live has chosen to fully use Statistics as a decisive instrument to deal with societal crises, whether they are related to environment, education, economy, energy, engineering, or excellence. While it is exciting that we are alive in the age of information, and while it is unfortunate that we find ourselves in the crisis of environment, it is only a bliss to have the opportunity to more effectively serve the cross-disciplinary cause of statistics, ecology, environment, and society in the research, training, and outreach setting.A hotspot can mean an unusual phenomenon, outlier, anomaly, aberration, outbreak, elevated cluster, or critical area. Treating Hotspot as an outlier, which may be extreme value, a method is proposed in this paper to identify it. The proposed method suggests some modification in ranked set sampling to identify hotspot which is towards very right tail of the distribution of sample values

Effect of Al Addition on the Microstructural Evolution of Equiatomic CoCrFeMnNi Alloy

The present investigation reports the effect of Aluminium-addition on the microstructural evolution in the equiatomic CoCrFeMnNi high entropy alloy. Aluminium was added to the alloy in varying quantity using the vacuum arc melting technique, and phase formation have been probed using X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The results indicate that the FCC phase in the alloy remains unaltered up to Al of 5 at.%. The higher amount of Al addition leads to the precipitation of B2 Al(Ni, Cr) in the FCC matrix. For Al 7%, typical phase separated microstructure consisting of FCC, and B2 phases have been observed. The microstructural changes lead to hardness variation from 1.3 to 2.2 GPa, mainly due to precipitation and solute solution hardening of FCC phase. For FCC phase, Al atoms being smaller in size can cause and lead to lattice distortion and improve yield strength. The results have been explained by detailed thermodynamical analysis using HEA3 database

Anisotropic deformation behavior under various strain paths in commercially pure titanium Grade 1 and Grade 2 sheets

In this study, the anisotropic deformation behavior in commercially pure titanium Grade 1 and Grade 2 sheets under various strain paths was examined. A small but sharp stress peak arose during tension following compression in the Grade 1 sheet when loaded in the rolling direction, and the occurrence of a stress peak was retarded when the sheet was subjected to cyclic loading; however, such behavior did not occur in the Grade 2 sheet. Similarly, the work-hardening rate was different between the initial and latter stages of compression following tension. These behaviors did not arise when the sheets were loaded in other directions. The type of active twin mode was different depending on the loading path. When loaded in the rolling direction in both Grade 1 and Grade 2 sheets, twinning and detwinning were active, respectively, during compression and tension following compression, whereas twinning and detwinning were active during tension and compression following tension. The twinning activity was much more pronounced in the Grade 1 sheet than in the Grade 2 sheet. The abovementioned stress-strain responses were presumed to result from twinning and detwinning activities as for magnesium alloy sheets. However, we concluded that the effect of twinning activity on the stress-strain curves was much smaller in the titanium sheet than in magnesium alloy sheets

Deformation behaviour at macro- and nano-length scales: The development of orientation gradients

The deformation behaviour of macrocrystalline and nanocrystalline nickel shows a striking similarity in terms of higher intragranular misorientation and a texture with dominant Brass component on rolling. This is in contrast to microcrystalline nickel, with lower intragranular misorientation and typical Copper type texture. This has been attributed to the free surfaces in macrocrystalline sample and grain boundaries in nanocrystalline sample. Experimental evidence of `Grain Boundary Affected Zone' (GBAZ) showing multi-slip in contrast to limited slip in the grain interiors has been provided. The similarity in evolution of texture and intragranular misorientation is explained on the basis of reduced contribution from the GBAZ at the two extreme length scales

Deformation behaviour of Titanium in torsion

The evolution of microstructure and texture in Hexagonal Close Pack commercially pure titanium has been studied in torsion in a strain rate regime of 0.001 to 1 s(-1). Free end torsion tests carried out on titanium rods indicated higher stress levels at higher strain rate but negligible change in the strain-hardening behaviour. There was a decrease in the intra-granular misorientation while a negligible change in the amount of contraction and extension twins was observed with increase in strain rate. The deformed samples showed a C-1 fibre (c-axis is first rotated 90 degrees in shear direction and then +30 degrees in shear plane direction) at all the strain rates. With the increase in strain rate, there was an increase in the intensity of the C-1 fibre and it became more heterogeneous with a strong {11(2)over-bar6}< 2(8)over-bar)63 > component. In the absence of extensive twinning, pyramidal < c+a > slip system is attributed for the observed deformation texture. The present investigation, therefore, substantiates the theoretical prediction of increase in strength of texture with strain rate in torsion

Texture evolution and operative mechanisms during large-strain deformation of nanocrystalline nickel

The large-strain deformation of nanocrystalline nickel was investigated at room temperature and cryogenic (liquid N-2) temperature. Deformation mechanisms ranging from grain boundary sliding to slip, operate due to a wide distribution of grain sizes. These mechanisms leave their finger print in the deformation texture evolution during rolling of nanocrystalline nickel. The occurrence and severance of different mechanisms is understood by a thorough characterization of the deformed samples using X-ray diffraction, X-ray texture measurements, electron back-scattered diffraction and transmission electron microscopy. Crystal plasticity-based viscoplastic self-consistent simulations were used to further substantiate the experimental observations. Thus, a comprehensive understanding of deformation behavior of nanocrystalline nickel, which is characterized by simultaneous operation of dislocation-dominated and grain boundary-mediated mechanisms, has been developed

Texture evolution and operative mechanisms during large-strain deformation of nanocrystalline nickel

The large-strain deformation of nanocrystalline nickel was investigated at room temperature and cryogenic (liquid N-2) temperature. Deformation mechanisms ranging from grain boundary sliding to slip, operate due to a wide distribution of grain sizes. These mechanisms leave their finger print in the deformation texture evolution during rolling of nanocrystalline nickel. The occurrence and severance of different mechanisms is understood by a thorough characterization of the deformed samples using X-ray diffraction, X-ray texture measurements, electron back-scattered diffraction and transmission electron microscopy. Crystal plasticity-based viscoplastic self-consistent simulations were used to further substantiate the experimental observations. Thus, a comprehensive understanding of deformation behavior of nanocrystalline nickel, which is characterized by simultaneous operation of dislocation-dominated and grain boundary-mediated mechanisms, has been developed

Deformation mechanisms during large strain deformation of nanocrystalline nickel

In this letter, a conclusive evidence of the operation of planar slip along with grain boundary mediated mechanisms has been reported during large strain deformation of nanocrystalline nickel. Dislocation annihilation mechanism such as mechanical recovery has been found to play an important role during the course of deformation. The evidences rely on x-ray based techniques, such as dislocation density determination and crystallographic texture measurement as well as microstructural observation by electron microscopy. The characteristic texture evolution in this case is an indication of normal slip mediated plasticity in nanocrystalline nickel

Generalized scaling of misorientation angle distributions at meso-scale in deformed materials

Scaling behaviour has been observed at mesoscopic level irrespective of crystal structure, type of boundary and operative micro-mechanisms like slip and twinning. The presence of scaling at the meso-scale accompanied with that at the nano-scale clearly demonstrates the intrinsic spanning for different deformation processes and a true universal nature of scaling. The origin of a 1/2 power law in deformation of crystalline materials in terms of misorientation proportional to square root of strain is attributed to importance of interfaces in deformation processes. It is proposed that materials existing in three dimensional Euclidean spaces accommodate plastic deformation by one dimensional dislocations and their interaction with two dimensional interfaces at different length scales. This gives rise to a 1/2 power law scaling in materials. This intrinsic relationship can be incorporated in crystal plasticity models that aim to span different length and time scales to predict the deformation response of crystalline materials accurately