Optimal estimation of interferometric phase for measuring surface deformation

In recent times, time-series interferometric synthetic aperture radar (InSAR) methods are developed to retrieve the deformation signal in non-urban areas from distributed scatterers (DS). Phase triangulation algorithm (PTA), an important step in these methods for filtering decorrelation noise from DS, aims at optimal estimation of the filtered wrapped interferometric phase values using InSAR data stack. The uniqueness of this research work lies in the incorporation of one such PTA only to provide an optimal set of wrapped interferometric phase values before phase unwrapping in the open source StaMPS processing environment. The proposed methodology, when adapted to measure surface deformation in Tehri reservoir rim region, Uttarakhand, India using Environmental Satellite (Envisat) C-band advanced synthetic aperture radar images, works efficiently and has enhanced the spatial coverage of measurement pixels compared to standalone PS-InSAR processing. It is also revealed from the one-dimension-line of sight velocity map that resulted velocity estimates are congruent with standalone PS-InSAR processing.     

Hyperspectral image classification based on morphological profiles and decision fusion

Extended morphological profile (EMP) is an important mathematical tool for extracting structural information from the hyperspectral images. However, the accuracy of the EMP-based classification is greatly influenced by the choice of structuring element (SE). In this article, two supervised classification frameworks multiclassifier system with morphological profiles (MCSMP) and MCSMP2 are proposed that exploit rich spectral and structural information of hyperspectral images using EMPs and multiclassifier system for better classification than conventional methods. The EMPs with SEs of multiple shapes are used instead of one particular shape to better detect the response from the structures in the image. The EMPs created from SEs of different shapes are independently classified followed by decision fusion to generate final classification map. The classification results are compared with the conventional pixelwise and other EMP-based methods. The experimental results from three different types of hyperspectral data sets demonstrate that the proposed methods have significantly improved the spectral approach and outperformed the other studied methods in terms of classification accuracy. The new methods are more robust to the noise and produce good classification accuracy with very limited training samples. Various decision fusion techniques are evaluated, which performed differently in tested scenarios. Two different classifiers, Support Vector Machine (SVM) and random forest, are used in the experiments. It is shown that the proposed methods perform better with random forest classifier.     

Parallel probabilistic relaxation labelling based on Markov random fields for spectral-spatial hyperspectral image classification

The large volume of data and computational complexity of algorithms limit the application of hyperspectral image classification to real-time operations. This work addresses the use of different parallel processing techniques to speed up the Markov random field (MRF)-based method to perform spectral-spatial classification of hyperspectral imagery. The Metropolis relaxation labelling approach is modified to take advantage of multi-core central processing units (CPUs) and to adapt it to massively parallel processing systems like graphics processing units (GPUs). The experiments on different hyperspectral data sets revealed that the implementation approach has a huge impact on the execution time of the algorithm. The results demonstrated that the modified MRF algorithm produced classification accuracy similar to conventional methods with greatly improved computational performance. With modern multi-core CPUs, good computational speed-up can be achieved even without additional hardware support. The CPU-GPU hybrid framework rendered the otherwise computationally expensive approach suitable for time-constrained applications.     

Functionalization of styrene–butadiene rubber with meta‐pentadecenyl phenol for better processing: A multifunctional additive and renewable resource

Meta‐pentadecenyl phenol, a nonisoprenoid phenolic lipid, is a renewable agricultural resource and also a byproduct of the cashew industry; it is popularly known as cardanol. This study throws light on the grafting of cardanol, which has been established as a multifunctional additive for natural rubber, onto the main‐chain backbone of styrene–butadiene rubber (SBR), a synthetic polymer used to imbibe the multifunctional properties of the former, such as those of a plasticizer, curing promoter, process aid, and antioxidant, into the latter. The grafting was carried out in the solution stage on a trial basis with a peroxide catalyst, and all of the grafting parameters were optimized with a Taguchi methodology. The grafting of cardanol onto the SBR backbone was successfully confirmed by UV–visible spectroscopy, Fourier transform infrared spectroscopy, and NMR analysis. Thermal analysis of the cardanol‐grafted styrene–butadiene rubber (C‐g‐SBR) revealed a higher thermal stability and better plasticizing effect than that those found in the virgin SBR. The rheological properties of the grafted rubber indicated the improvement of the pseudo‐plastic (shear‐thinning) nature compared to that in gum SBR. The unfilled C‐g‐SBR vulcanizates exhibited physicomechanical properties comparable to 5‐phr processing‐oil‐containing SBR [oil‐plasticized styrene–butadiene rubber (OPSBR)] vulcanizates. The carbon‐black‐filled C‐g‐SBR vulcanizates exhibited improved plasticization, a faster curing rate, easy processability, and better physicomechanical properties compared to the 5‐phr OPSBR vulcanizates. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45150.     

Gelatin–κ-carrageenan polyelectrolyte complex hydrogel compositions for the design and development of extended-release pellets

Present investigation was aimed to develop Zaltoprofen-loaded extended-release (ER) pellets formulation for prolonged release. The matrix type of pellets was prepared by extrusion-spheronization technique using calcium chloride-mediated gelatin–κ-carrageenan (G–κ-Carr) polyelectrolyte complex (PEC) hydrogel using rotatable central composite design. The pellets were characterized for physicochemical, morphological, solid-state characterization and flow properties. The formulations were also estimated for drug release and mucoadhesion potential. The optimized formulation (F1) containing 5:5 ratio of G–κ-Carr showed a drug release up to 98.2% and mucoadhesion of 95%. Optimized formulation showed acceptable release pattern, and hence would be viable alternative to ER type of formulations.     

Integral method of analysis of fischer-tropsch synthesis reactions in a catalyst pellet

A generalized integral method is developed to analyze complex reactions in a catalyst pellet. This method is valid for any kinetics and takes into account both internal and external heat and mass transfer effects. The integral equations are solved for a Fischer-Tropsch kinetic model to obtain effectiveness factors. Isothermal multiplicities are observed for low values of the surface coverage parameter α(α = 1/K₁p_co,0), and low values of the parameter σ₂₁ (ratio of Thiele moduli for H₂ and CO). The effectiveness factor is mildly sensitive to the external resistances.     

TEMPERATURE DISTRIBUTION DURING ELECTRO-DISCHARGE ABRASIVE GRINDING

The objective of this work is to develop a finite element method (FEM) based mathematical model to simulate the hybrid machining process of grinding and electric discharge machining (EDM), named as Electro-discharge abrasive grinding (EDAG), for temperature distribution in the workpiece. Two different finite element codes have been developed to calculate the temperature distribution due to grinding heat source and EDM heat source separately. The transient temperature field within workpiece due to cut-off grinding is determined due to moving rectangular heat source. Gaussian heat distribution of power within a spark has been considered in the calculation of temperature distribution due to EDM. Temperature distribution in the workpiece due to combined process is obtained by using superposition. The simulation shows a sudden rise in temperature at the spark location. The predicted results can be used for calculation of thermal stresses, which play a major role as far as high-quality product requirements are concerned.     

Modeling and simulation of magnetic abrasive finishing process

Magnetic abrasive finishing (MAF) is one of the advanced finishing processes, which produces a high level of surface quality and is primarily controlled by a magnetic field. In MAF, the workpiece is kept between the two poles of a magnet. The working gap between the workpiece and the magnet is filled with magnetic abrasive particles. A magnetic abrasive flexible brush (MAFB) is formed, acting as a multipoint cutting tool, due to the effect of the magnetic field in the working gap. This paper deals with the theoretical investigations of the MAF process. A finite element model of the process is developed to evaluate the distribution of magnetic forces on the workpiece surface. The MAF process removes a very small amount of material by indentation and rotation of magnetic abrasive particles in the circular tracks. A theoretical model for material removal and surface roughness is also proposed accounting for microcutting by considering a uniform surface profile without statistical distribution. Numerical experiments are carried out by providing different routes of intermittent motion to the tool. The simulation results are verified by comparing them with the experimental results available in the literature.     

Theoretical calculation of hydrogen desorption energies of calcium hydride clusters

Recently calcium hydride has attracted attention as a possible component in ternary complex hydrides such as Ca(AlH₄)₂, Ca₂SiH_x and quaternary complex hydrides of the type Li–B–Ca–H. Although in bulk form CaH₂ decomposes reversibly above 600° centigrade we were motivated to see whether calcium hydride in cluster form has properties suitable for hydrogen storage. We report here the results of DFT calculations using VASP^® package for clusters Ca_nH_2n with n = 1, 2, 3, 4, 6, 8, 10, 12, 14, 16, 20 to get the ground state geometries, energies, bond lengths, and desorption energies, after molecular dynamics optimization. The desorption energy vs. cluster size n curve showed that the desorption energy goes up sharply to ∼1.4 eV per H₂ for n up to 4, followed by a broad maximum of ∼1.8 eV per H₂ around n = 12–14, and then tapers off to a nearly constant value of 1.6 eV per H₂ approximating bulk behavior, which compares favorably with previously reported results. Comparison of these results with those of Mg_nH_2n shows that Ca_nH_2n has a lesser potential as a hydrogen storage medium.     

Processing of duplex stainless steel by WEDM

This study investigates the manufacturing process of 2205 duplex stainless steel by wire electrical discharge machining where the effects of pulse-on time (PONT), wire tension and pulse-off time (POFT) on surface finish, kerf width, and material removal rate (MRR). It was found that the kerf width was unchanged with the change of PONT at long pulse-of time and higher wire tension. However, it decreased initially and then increased due to the rise of PONT at low values of wire tension and POFT. Low wire tension and PONT, POFT and contributed towards widest kerf. Longer PONT increased MRR due to higher machining/processing speed. Lower wire tension and shorter POFT increased MRR more than that of higher wire tension and POFT. Craters and recast layer were on the machined surfaces at all machining conditions. Increased PONT raised surface roughness at the lower POFT and tension in the wire. The surface finish at high wire tension and longer PONT is always better than that at smaller PONT and lower tension in the wire. The microstructure underneath the recast layer remains unchanged and the failure of wire electrode occurred at higher wire tension, longer PONT and shorter POFT.