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Constrained controllability of nonlinear neutral fractional integrodifferential systems

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Journal of Control and Decision 2017年第2期4卷 81-99页

作者： s.divya K.Balachandran Department of Mathematics Bharathiar UniversityCoimbatoreIndia

In this paper,we study the complete controllability for a class of nonlinear neutral fractional integro-differential systems in a finite interval of time by means of controls whose initial and final values can be assigned in *** result is achieved using the Banach fixedpoint theorem and schauder’s fixed-point *** numerical examples are provided to demonstrate the effectiveness of the main result.

关键词： Constrained controllability neutral fractional integrodifferential equations fixed point theorem

Electronic and optical properties of TiO_2 and its polymorphs by Z-scan method

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Chinese Physics B 2014年第8期23卷 340-344页

作者： s. divya V P N Nampoori P Radhakrishnan A Mujeeb International school of Photonics Cochin University of Science and Technology

TiO2 is a material which has attracted considerable attention from the scientific community for its innumerable prop- erties. TiO2 is known to exist in nature in three different crystalline structures： rutile, anatase, and brookite. Anatase and rutile TiO2 films have been widely characterized for their potential applications in solar cells, self-cleaning coatings, and photocatalysis. In the present report, the third-order nonlinear susceptibilities of TiO2 and its polymorphs, anatase, and rutile, prepared by the sol-gel technique followed by heat treatment are investigated using the Z-scan technique at a wavelength of 532 nm with a duration of 7 ns. Imaginary and real values of Z（3） for amorphous, anatase, and rutile are also calculated and found to be 5 × 10^-19 m2/V2, 27 × 10^-19 m2/V2, 19 × 10^-19 m2/V2, respectively. It is found that the values of the optical constants of amorphous TiO2 after heat treatment vary considerably. It is assumed that this could be due to the variation in the electronic structure of TiO2 synchronous with the formation of its polymorphs, anatase, and rutile. Amorphous TiO2 is marked by the localization of the tail states near the band gap, whereas its crystalline counterparts are characterized by completely delocalized tail states.

关键词： excitons reverse saturable absorption (RsA) excitonic nonlinearity

Conformally symmetric wormhole solutions supported by non-commutative geometry in f(Q,T)gravity

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Communications in Theoretical Physics 2024年第2期76卷 111-124页

作者： Chaitra Chooda Chalavadi V Venkatesha N s Kavya s V divya Rashmi Department of P.G.studies and Research in Mathematics Kuvempu UniversityShankaraghattaShivamogga 577451KarnatakaIndia Department of Mathematics Vidyavardhaka College of EngineeringMysuru—570002India

This paper investigates wormhole solutions within the framework of extended symmetric teleparallel gravity,incorporating non-commutative geometry,and conformal *** achieve this,we examine the linear wormhole model with anisotropic fluid under Gaussian and Lorentzian *** primary objective is to derive wormhole solutions while considering the influence of the shape function on model parameters under Gaussian and Lorentzian *** resulting shape function satisfies all the necessary conditions for a traversable ***,we analyze the characteristics of the energy conditions and provide a detailed graphical discussion of the matter contents via energy ***,we explore the effect of anisotropy under Gaussian and Lorentzian ***,we present our conclusions based on the obtained results.

关键词： traversable wormhole f(Q T)gravity energy conditions non-commutative geometry conformal motion

Experimental study of the interspecific competition between two sibling marine herbivorous rotifers in relation to food availability and initial population density

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Acta Oceanologica sinica 2012年第4期31卷 113-126页

作者： divya s P Kathiresan K Asha P sekar V Rajasekaran R Centre of Advanced study in Marine Biology Faculty of Marine SciencesAnnamalai University school of Environmental studies Cochin University of Science and Technology

Our laboratory study concerns the competitive interaction between two marine rotifer species Bra- chionus plicatilis and Brachionus rotundiformis at five algal （ Nannochloropsis salina） concentrations （0.4＊106 to 32.4x106 cells/ml） and at four initial inoculation densities （numerically, 100% B. pli- catilis; 75% B. plicatilis and 25% B. rotundiforrnis, 50% each of the two species; 25% B. plicatilis and 75% B. rotundiformis and 100% B. rotundiforrnis. The initial biomass varied as 0.33 and 0.22 #g/ml for B. plicatilis and B. rotundiformis respectively. Experiments were performed at （25±1）C. Population densities were enumerated and the medium was changed daily up to 8 d in the ex- periment. At the lowest food level tested, B. rotundiformis formed superior competitor than B. plicatilis, regardless of starting inoculation density. Generally when the food concentrations in- creased, B. plicatilis showed a greater increase in biomass than B. rotundiforrnis. B. rotundiformis formed the largest in population growth, regardless of increasing food concentrations. When grown alone, B. plicatilis reached peak abundances of （1.311 5±0.028） and （137.5±0.014） μg/ml at low and high food densities respectively. The corresponding values of B. rotundiformis were 0.724 5±0.016 and 18.15±0.021. The adverse effects of B. rotundiforrnis on the peak abundances of B. plicatilis were observed at the lowest food level and higher initial density. The rate of population growth in controls varied from （0.792±0.162） to （1.482±0.132） ttm/d for B. plicatilis and （0.445~0.041） to （0.856±0.012） μm/d for B. rotundiformis, depending on food level. When both species were intro- duced together, low food levels favoured higher abundance of B. rotundiforrnis than B. plicatilis, suggesting that increased population density of the smaller B. rotundiforrnis was more successfull than larger B. plicatilis in brackish waters. Our work reveals that available food （type and quan- tity） along with starting inoculat

关键词： competition food level B. plicatilis B. rotundiformis population density interspecificcompetition

Intensity and composition-dependent sign reversal of non-linearity in TiO_2/CeO_2 nanocomposites

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Chinese Physics B 2014年第3期23卷 298-302页

作者： s.divya V.P.N.Nampoori P.Radhakrishnan A.Mujeeb International school of Photonics Cochin University of Science and Technology

CeO2/TiO2 composite nanoparticles with different Ce/Ti molar ratios have been successfully synthesized via sol-gel method. It was found that the band gap of the nanocomposite is tunable by varying Ce/Ti content. The nonlinear response of the sample was studied by using the nanosecond laser pulses from a Q switched Nd：Yag laser employing the Z-scan method. Open aperture Z-scan experiment revealed that with the increase in the CeO2 amount in the nanocomposite, the non-linearity of the composite increases, and it was assumed that this could be due to the modification of TiO2 dipole symmetry by the addition of CeO2. Closed aperture Z-scan experiment showed that when the CeO2 amount increases, positive nonlinear refraction decreases, and this could be attributed to the increase in the two photon absorption which subsequently suppresses the nonlinear refraction.

关键词： sol-gel method non-linearity Z-scan experiment reversesaturation absorption curve

Tailoring optical properties of TiO_2 in silica glass for limiting applications

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Chinese Physics B 2014年第3期23卷 303-307页

作者： s.divya Indu sebastian V.P.N.Nampoori P.Radhakrishnan A.Mujeeb International school of Photonics Cochin University of Science and Technology

We present the linear and nonlinear optical studies on TiO2-siO2 nanocomposites with varying compositions. Opti- cal band gap of the material is found to vary with the amount of siO2 in the composite. The phenomenon of two-photon absorption （TPA） in TiO2/siO2 nanocomposites has been studied using open aperture Z-scan technique. The nanocom- posites show better nonlinear optical properties than pure TiO2, which can be attributed to the surface states and weak dielectric confinement of TiO2 nanoparticles by siO2 matrix. The nanocomposites are thermally treated and similar studies are performed. The anatase form of TiO2 in the nanocomposites shows superior properties relative to the amorphous and rutile counterpart. The involved mechanism is explained by rendering the dominant role played by the excitons in the TiO2 nanoparticles.

关键词： reverse saturable absorption (RsA) optical limiting excitons

Improving the photocatalytic performance of TiO2 via hybridizing with graphene

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Journal of semiconductors 2017年第6期38卷 24-31页

作者： K s divya Athulya K Madhu T U Umadevi T suprabha P.Radhakrishnan Nair suresh Mathew school of Chemical sciences Mahatma Gandhi University Kottayam 686 560 Kerala India Advanced Molecular Materials Research Centre Mahatma Gandhi University Kottayam 686 560 Kerala India

In this paper an improvement in the photocatalytic performance of TiO2 was carried out via hybridizing with ***-TiO2（GR-TiO2/nanocomposites with different weight addition ratios of graphene oxide（GO）have been prepared via a facile microwave irradiation of GO and tetrabutyl titanate in isopropyl *** spectroscopy（Rs）,X-ray diffraction（XRD）,scanning electron microscopy（sEM）,transmission electron microscopy（TEM）,UV–visible spectroscopy（UV–vis）,Fourier transform infrared spectra（FTIR）,energy dispersive X-ray spectroscopy（EDX）and photoluminescence spectra（PL）are employed to determine the properties of the *** irradiation can heat the reactant to a higher temperature in a short time,simultaneously GO is reduced to graphene and TiO2 nanoparticles grown on the surface of ***-TiO2 nanocomposites synthesized via this approach have efficient electron conductivity in GR,resulting in a reduced electron–hole recombination *** the synthesized nanocomposites,GT-8wt% exhibited the best photocatalytic activity toward photocatalytic degradation of *** current work provides a new insight for the fabrication of GR-TiO2 nanocomposites within a short reaction time and also explains the mechanism of photocatalysis employing radical and hole scavengers.

关键词： graphene (GR) tetrabutyl titanate (TBT) GR-TiO2 nanocomposites methylene blue photocatalysis

Role of Metallic Nanofillers on Mechanical and Tribological Behaviour of Carbon Fabric Reinforced Epoxy Composites

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Materials sciences and Applications 2018年第9期9卷 740-750页

作者： G. s. divya B. suresha Department of Mechanical Engineering The National Institute of Engineering Mysuru India Department of Automobile Engineering Dayananda Sagar College of Engineering Bengaluru India

In this study, hybrid composites based on carbon fabric and epoxy (C/Ep) were fabricated by hand lay-up method followed by compression moulding. The C/Ep with optimum carbon fiber (60 wt%) was chosen as a reference material, and to it, the metallic nanoparticles like aluminum (Al) and zinc (Zn) of different wt% (0.5 and 1.0) were included as secondary fillers. To understand the synergism effect of these hybrid reinforcements, mechanical properties and tribological behavior of composites were studied. From the test results, it was proved that hybridization improved the mechanical and tribological properties. The C/Ep consisting of 0.5 wt% Zn and Al showed higher tensile properties in comparison with all other fabricated composites. Increase in flexural strength and flexural modulus also observed as the filler content increased in C/Ep composite. Higher impact strength is noted at 1 wt% Zn filled C/Ep composite. Wear test data revealed that 0.5 wt% Zn in C/Ep has got superior wear resistance. Wear mechanisms were discussed using scanning electron micrographs of selected worn surfaces of the composites.

关键词： Carbon-Epoxy Metallic Nanofillers Mechanical Properties Wear Wear Mechanisms

Bearing capacity of foundations on rock slopes intersected by non-persistent discontinuity

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International Journal of Mining science and Technology 2020年第5期30卷 669-674页

作者： divya shaunik Mahendra singh Department of Civil Engineering Indian Institute of Technology RoorkeeRoorkee 247667India

Rocks encountered in foundations of heavy structures are invariably intersected by discontinuities(joints).In the past,several studies have been performed by researchers to incorporate the effect of fully persistent joints in the assessment of the load-carrying capacity of ***,in the field,the joints are non-persistent,and an assumption of full persistency will underestimate the ***,shaunik&singh have studied the influence of non-persistency,number of joint segments and discontinuity orientation on the strength behaviour of rock specimens(shaunik and singh,2019).Bell’s approach can be used to obtain the bearing capacity of shallow foundations placed in jointed *** the present study,results of the experimental work(shaunik and singh,2019)conducted by shaunik&singh have been used to suggest expressions by extending Bell’s approach for computing bearing capacity of the foundation placed near the crown of a rock *** to use design charts are also presented for field ***,a real-life problem from Indian Garhwal Himalayas is considered,and the approach suggested in this study is utilised to obtain the bearing capacity of a bridge foundation as a function of uniaxial compressive strength(UCs)of intact rock,joint friction,spacing and orientation of joint,nonpersistency and number of joint segments.

关键词： Uniaxial compressive strength(UCs) Joint segment Discontinuity Non-persistency Bell’s approach