DCT-based iris recognition

This paper presents a novel iris coding method based on differences of discrete cosine transform (DCT) coefficients of overlapped angular patches from normalized iris images. The feature extraction capabilities of the DCT are optimized on the two largest publicly available iris image data sets, 2,156 images of 308 eyes from the CASIA database and 2,955 images of 150 eyes from the Bath database. On this data, we achieve 100 percent correct recognition rate (CRR) and perfect receiver-operating characteristic (ROC) curves with no registered false accepts or rejects. Individual feature bit and patch position parameters are optimized for matching through a product-of-sum approach to Hamming distance calculation. For verification, a variable threshold is applied to the distance metric and the false acceptance rate (FAR) and false rejection rate (FRR) are recorded. A new worst-case metric is proposed for predicting practical system performance in the absence of matching failures, and the worst case theoretical equal error rate (EER) is predicted to be as low as 2.59 times 10^-1 available data sets     

Synthesis and Characterization of Polyurea Resin for Dielectric Coating Applications

In this article, polyurea coatings were synthesized by reaction between toluene diisocyanate, and polyether difunctional and trifunctional amines PO-1 and PO-2 by incorporating urea linkage. The isocyanate-terminated prepolymers formed were further reacted with short-chain amines as chain extender as well as curing agents. These resins were synthesized by varying the molar ratio of amines and isocyanate and keeping the molar ratio of other monomers constant. The presence of functional groups were determined using Fourier transform infrared spectroscopy. The thermal stability of polymers was determined using the thermogravimetric analysis and differential scanning calorimetry. The polymers were further tested for mechanical and electrical properties. It was observed that on increasing the hard segments in the polymer the electrical properties increase whereas elongation decrease. As isocyanate content increases, crosslinking increases resulting in improvement in dielectric properties. The maximum dielectric strength observed was 45 kV mm^?1 and dissipation factor was 0.068.     

Terpolymers of acrylamide,acrylic acid and acrylonitrile: further characterization and biodegradation studies

Tercopolymers of acrylamide (AM), acrylic acid (AA) and acrylonitrile (AN) synthesized by free radical solution polymerization have been characterized using ¹³C NMR and thermal analysis (DSC) techniques. Incorporation of the above three monomers was confirmed by ¹³C NMR analysis. The tercopolymers have similar polymer backbone structures, and a limited branching in the main chain was found as evidenced by DSC analysis. Microbiological observations of polymer‐dependent growth and of respiration studies using a soil bacterial isolate, suggested that these tercopolymers were used as growth substrate and were therefore biodegradable. © 2000 Society of Chemical Industry     

A self-organizing fuzzy inference system for electric fieldoptimization of HV electrode systems

Development of efficient methods for optimum design of electrode and insulator contour in a HV apparatus has been an important area of research in the recent past. A self-organizing fuzzy inference system is developed for electrode optimization which is an improved version over traditional iterative approach of optimization and more recent methods employing neural networks. This fuzzy system has been implemented for two practical examples of an axisymmetric single-phase gas-insulated system (GIS) bus termination and a disconnecter switch configuration. Improved electric stress distribution demonstrates the usefulness of the proposed method. A new methodology for automatic generation of the fuzzy rule base from the input-output data set is also proposed in this scheme. This fuzzy system is much simpler and less time consuming to implement compared to other optimization techniques presently available for optimization of HV electrodes     

Synthesis and characterization of homopolymer of 2-ethylhexyl acrylate and its copolymers with acrylamide,acrylonitrile, and methyl methacrylate

A homopolymer of 2-ethylhexyl acrylate (EHA) was synthesized by a free-radical solution polymerization technique. Copolymers of EHA with acrylonitrile (AN), acrylamide (AA), and methyl methacrylate (MMA) in various ratios were also synthesized by the same pro-cedure. These were characterized by PNMR, ¹³C-NMR, FTIR, GPC, and viscosity mea-surements. The reactivity ratios of various monomers were determined. The viscosity mea-surements were carried out in four different solvents: ethyl acetate (EA), methyl ethyl ketone (MEK), toluene (TL), and tetrahydrofuran (THF). The studies were done at three different temperatures of 30,35 and 40°C. The activation parameters of the viscous flow were computed for different systems. The intrinsic viscosity of the copolymers increased with temperature in MEK and EA. This trend showed reversal for the other two solvents. The results are discussed in detail. © 1996 John Wiley & Sons, Inc.     

Subject-specific strength percentile determination for two-dimensional symmetric lifting considering dynamic joint strength

Multibody System Dynamics - This paper describes an efficient optimization method for determining the subject-specific strength percentile and predicting the maximum weight lifting motion by...     

Optical and bio-sensing characteristics of ZnO nanotubes grown by hydrothermal method

ZnO nanostructures were fabricated on copper substrates by hydrothermal method at an optimized growth temperature of -95 degrees C. Structural properties were investigated by field emission scanning electron and transmission electron microscopy. Distinct morphologies were found to be formed at different growth times. The formation of nanotubes mainly involved the initial nucleation followed by the growth of nanorods at 95 degrees C, and then with the increase of dissolution time at room temperature, the preferential chemical dissolution of the metastable Zn-rich [0001] polar surfaces resulted in removing the atoms from the surfaces, thus leading to the thinning of the wall of the nanostructures. Completely hollow ZnO nanotubes could be obtained at a high dissolution time. The room temperature photoluminescence and optical absorption properties of ZnO nanotubes have been studied as a function of dissolution time. The efficacy of ZnO nanotubes for glucose sensing applications has been studied.     

A semiautomatic approach for segmentation of carotid vasculature from patients’ CTA images

Segmentation of vasculature specific to the patients’ carotid vasculature is a complicated and challenging task because of its complex geometrical structure and interconnections. Accurate or approximate digital phantoms of the vasculature are extremely useful in quick analysis of the vascular geometry and the modelling of blood flow in the cerebrovasculature. All these analyses lead to effective diagnosis and detection/localization of the diseased arterial segment in the cerebrovasculature. In this work, we have proposed a semiautomatic geodesic path propagation algorithm based on fuzzy distance transform to generate digital cerebrovascular phantoms from the patients’ CT angiogram (CTA) images. We have also custom-developed a 2-D/3-D user interface for accurate placement of user-specified seeds on the input images. The proposed method effectively separates the artery/vein regions from the soft bones in the overlapping intensity regions using minimal human interaction. Qualitative results along with 3-D rendition of the segmented cerebrovasculature on eight patients’ CTA images are presented here.