Palampur, India
Palampur, India

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Teo E.J.,National University of Singapore | Bettiol A.A.,National University of Singapore | Xiong B.,National University of Singapore | Breese M.B.H.,National University of Singapore | Shuvan P.T.,Sri Sai University
Optics Express | Year: 2010

In this paper, we demonstrate a direct method of fabricating an all-silicon, single-mode Bragg cladding rib waveguide using proton beam irradiation and subsequent electrochemical etching. The Bragg waveguide consists of porous silicon layers with a low index core of 1.4 that is bounded by eight bilayers of alternating high and low refractive index of 1.4 and 2.4. Here, the ion irradiation acts to reduce the thickness of porous silicon formed, creating an optical barrier needed for lateral confinement. Singlemode guiding with losses as low as approximately 1 dB/cm were obtained for both TE and TM polarization over a broad range of wavelengths from 1525 nm to 1625 nm. Such an approach offers a method for monolithic integration of Bragg waveguides in silicon, without the need for multiple processes of depositing alternating materials. © 2010 Optical Society of America.


Baczynski M.,University of Silesia | Jayaram B.,Sri Sai University | Jayaram B.,Slovak University of Technology in Bratislava
Fuzzy Sets and Systems | Year: 2010

In this paper, we attempt a systematic study of QL-implications. Towards this end, firstly, we investigate the conditions under which a QL-operation becomes a fuzzy implication without imposing any conditions on the underlying operations. Following this, we discuss the conditions under which this family satisfies some desirable algebraic properties. Based on the obtained results and existing characterization results, the intersections between QL-implications and the two most established families of fuzzy implications, viz., (S,N)- and R-implications are determined. It is shown that QL-implications contain the set of all R-implications obtained from left-continuous t-norms that are also (S,N)-implications. Finally, the overlaps between QL-implications and the recently proposed f- and g-implications are also studied. © 2008 Elsevier B.V. All rights reserved.


Sharma D.,Singhania University | Thakur S.K.,Lovely Professional University | Thakur S.K.,Sri Sai University
Philosophical Magazine | Year: 2011

Bulk samples of (Se100-xBix)90Te 10 (x = 0, 0.5, 1, 1.5, 2, 2.5 and 3 at%) system were prepared using the melt quenching technique. The amorphous nature of bulk samples was confirmed using X-ray diffraction. The compositional variation in physical properties, namely density ρ, molar volume Vm, compactness δ, average coordination number m, average number of constraints Ncon, number of lone pair electrons L, bond energy, average heat of atomization Hs, mean bond energy E and glass transition temperature Tg of the system have been studied. The mean bond energy has been calculated using the chemical bond approach (CBA). The glass transition temperature was calculated using the Tichy-Ticha method and was found to increase with Bi content. The mean bond energy was found to be proportional to the glass transition temperature. Average coordination number, average number of constraints, mean bond energy and density increase, whereas the average heat of atomization decreases with increasing Bi content in Se-Te alloys. The energies of the various possible bonds have also been determined. © 2011 Taylor & Francis.


Sharma D.,Singhania University | Thakur S.K.,Sri Sai University
Defect and Diffusion Forum | Year: 2011

Alloys of (Se100-xBix)90Te10 (x = 0, 0.5, 1, 1.5, 2, 2.5, 3 at.%) were prepared by using a conventional melt-quench technique. The samples under investigation were characterized using X-ray diffraction (XRD) and differential analysis (DTA) at a heating rate of 10K/min. It was found, from the XRD studies, that the alloys were amorphous in nature. The glass transition temperatures of the alloys were found to increase with increasing bismuth content. This increase in the glass transition temperature was explained on the basis of a chemically ordered network model. © (2011) Trans Tech Publications, Switzerland.


Kiran P.P.,Tata Institute of Fundamental Research | Kiran P.P.,University of Hyderabad | Bagchi S.,Tata Institute of Fundamental Research | Bagchi S.,University of Hyderabad | And 4 more authors.
Optics Express | Year: 2010

We present measurements of the supercontinuum emission (SCE) from ultrashort Ti:Saph laser pulse filamentation in air in a tightly focused geometry. The spectral broadening of SCE indicates that peak intensities exceed the clamping value of a few 1013 W/cm2 obtained for filamentation in a loose focusing geometry by at least one order of magnitude. We provide an interpretation for this regime of filamenation without intensity clamping. © 2010 Optical Society of America.


Kiran P.P.,Tata Institute of Fundamental Research | Kiran P.P.,University of Hyderabad | Bagchi S.,Tata Institute of Fundamental Research | Krishnan S.R.,Sri Sai University | And 3 more authors.
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2010

We observe the complete dynamics of the propagation of very intense, femtosecond laser pulses in air under tight focusing conditions via direct imaging of the entire interaction zone. The whole life history of the focused pulses is then reconstructed by means of numerical simulations. We show that beam breakup leads to a dual-rate increase in filament numbers with laser power. Linearly and circularly polarized pulses give rise to beam breakup and fusion governed by external focusing conditions. For tight focusing conditions, intensity saturation due to plasma generation and nonlinear losses does not limit the intensity growth, thereby giving access to a new propagation regime featured by an efficient laser energy deposition in fully ionized air and intense 1015 W/cm2 pulses at the focus. © 2010 The American Physical Society.


Rana A.K.,Sri Sai University | Singha A.S.,National Institute of Technology Hamirpur
Polymer Science - Series A | Year: 2015

Recently, natural fibers reinforced polymer composites have been finding an extensive use in dielectric and automobile applications. So keeping in view their applications part, effect of fiber’s surface functionalization on dielectric and flammability properties of resulted unsaturated polyester (UPE) matrix based bio-composites have been examined in present research paper. Raw, silanated and acrylonitrile (AN) graft copolymerized Cannabis indica [Cannabis indica-g-poly(AN)] fibers have been used in different proportions for the fabrication of composite materials. Optimization of fibers proportion has been carried out by evaluating mechanical properties like tensile, compressive and flexural strength of composite materials. The composite materials with optimized mechanical properties have been further evaluated for their flammability and dielectric properties i.e., dielectric strength, loss, dissipation factor and dielectric constant. Both flammability and dielectric properties of polymer composites were found to improve after surface functionalization of fibers. In addition, composite samples were also evaluated for their thermal, morphological and physico-chemical properties. © 2015, Pleiades Publishing, Ltd.


Manikandan J.,Sri Sai University | Manikandan M.,Anna University
International Journal of Control Theory and Applications | Year: 2016

A modulation is a process by which some characteristics of high frequency carrier signal is varied in accordance with the instantaneous value of another signal. In this paper presents the basic modulation and demodulation principle of Quadrature Amplitude Modulation (QAM) and Binary Phase-Shift Keying (BPSK). The QAM and BPSK modulation and demodulation algorithm is designed and implemented for OFDM system. QAM is widely used multi-level modulation technique, with a variety of application in data radio communication system. BPSK is a simple but significant carrier modulation scheme. The design of modulation and demodulation is done through Very Large Scale Integration (VLSI) system design environment.QAM and BPSK are the important modulation techniques for wireless communication system. These two modulations have different types of advantages in terms of less area, high speed and lower power consumption. QAM modulation has high speed to modulate the digital input whereas BPSK has low speed due to less angle coefficient. QAM and BPSK modulation and demodulation techniques are simulated by using ModelSim 6.3C and synthesized by Xilinx 12.4i. © International Science Press.


Babu D.R.,Sri Sai University | Rao G.N.,Sri Sai University
Journal of Food Science and Technology | Year: 2013

Methanolic extracts of cap and stipe of commercially obtained mushrooms Agaricus bisporus, Hypsizygus ulmarius, and Calocybe indica were analyzed for their antioxidant activity in different chemical systems including reducing power, free radical scavenging, ferric reducing antioxidant power (FRAP), superoxide scavenging, peroxide scavenging, metal chelating activities and electrochemical behavior. Scavenging effects on 2,2-diphenyl-1-picrylhydrazyl radicals were moderate (43.5-59.0%) at 1.5 mg/ml. Chelating effects on ferrous ions were moderate to excellent (40.6-96.1%) at 20 mg/ml. At 12 mg/ml, the reducing powers were excellent (2.54-1.71). FRAP results were in the range 2.15-0.98 at 16 mg/ml. The ability to scavenge H2O2 was moderate to excellent (48.9-97.7%) at 1.5 mg/ml. At 10 mg/ml, Agaricus bisporus cap proved to be better at scavenging superoxide radicals than others. Similar electrochemical responses of all extracts suggested similar electroactive chemical composition. The total phenols in the extracts ranged from 14.73-26.72 mg/g.The total flavonoid content ranged from 1.12-2.17 μg/g. © 2011 Association of Food Scientists & Technologists (India).


Marpudi S.L.,Sri Sai University | Abirami L.S.S.,Sri Sai University | Pushkala R.,Sri Sai University | Srividya N.,Sri Sai University
Indian Journal of Biotechnology | Year: 2011

Papaya is one of the main tropical fruits of India. The desiccation of fruits and perishable nature of papaya is a major drawback during transportation to distant markets and storage during glut in the market. Aloe vera gel, mainly composed of polysaccharides, has been recently explored as an edible coating owing to its antifungal activity. To improve the performance of edible coatings, various substances/chemical additives have been incorporated. Papaya leaf is a potential antifungal agent that could be used as a bio-based additive, especially, by papaya growing farmers. The present study was carried out to evaluate the ability of Aloe gel based antimicrobial coatings to reduce/control the loss of post harvest fruit quality in papaya and to compare the effects with a natural polysaccharide-chitosan, an established coating material with antifungal activity. Freshly harvested papaya fruits were coated with Aloe gel/AG (50%), papaya leaf extract/PLE incorporated Aloe gel (1:1) and 2.5% chitosan. The coated and uncoated (control) fruits were stored at 30±3°C and 42-55% RH for 15 d. Physical (PLW, fruit size), chemical (pH, titrable acidity and TSS), and sensory characteristics (colour, taste & firmness); fruit disease index (FDI), and marketability were analyzed at regular intervals during the storage period. The coated fruits survived the storage period of 15 d, whereas, all the uncoated controls decayed within 10 d. The uncoated/control fruits exhibited significantly greater changes in all the parameters tested. Among the coated fruits, PLEAG treated fruits exhibited least changes followed by AG and chitosan coated fruits. The coatings controlled the PLW, ripening process (chemical changes, colour development and softening of fruit tissue) and decay to a great extent and thereby extended the shelf life quality of the fruits. Marketability was also found to be better for PLEAG coated fruits among the 3 coatings, followed by AG and chitosan coated fruits. The effectiveness of AG coating was found to improve on incorporation of PLE. Shelf life could be further extended in low temperature storage. This is probably the first study on utilizing a natural alternative such as Aloe-gel and PLE to extend shelf life quality in papaya. On the basis of the over all physiological changes, Aloe gel based antimicrobial coating has been identified as a suitable method to extend the shelf life of papaya fruits.

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