Wyniki wyszukiwania - Biblioteka Nauki

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Observations on cephaline gregarine Steinina lunata sp. n. (Actinocephalidae) from Myllocerus undecimpustulates maculosus

100%

Kaur D. , Bala P.

Acta Protozoologica

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1988

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tom 27

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nr 1

2

Generalized thermoelastic plane harmonic waves in materials with voids

100%

Sharma J. N. , Kaur D.

International Journal of Applied Mechanics and Engineering

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2008

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tom Vol. 13, no 4

1019-1043

EN

The aim of the present paper is to give a detailed account of the plane harmonic generalized thermoelastic waves in solids containing vacuous voids based on the modified fourier law of heat conduction. The general characteristic equation being quartic suggests that there are four longitudinal waves, namely: quasi-elastic [...], quasi-thermal [...], volume fraction [...] and micro-thermal [...], in addition to transverse waves, which can propagate in such solids. The transverse waves get decoupled from the rest of the field quantities and hence remain unaffected due to temperature variation and porosity effects. These waves travel without attenuation and dispersion. The other generalized thermoelastic waves are significantly influenced by the interacting fields and hence suffer both attenuation and dispersion. The general complex characteristic equation has been solved by using descartes algorithm along with irreducible case of cardano's method with the help of demoivre's theorem in order to obtain phase speeds, attenuation coefficients and specific loss factor of energy dissipation. The propagation of waves in non-heat conducting solids has also been discussed. Finally, the numerical solution of the secular equation is carried out to compute phase velocities, attenuation coefficients and specific loss factors of thermoelastic waves which are presented graphically.

3

Investigation on multiferroic properties of BiFeO3 ceramics

80%

Shariq M. , Kaur D. , Chandel V. S. , Siddiqui M. A.

Materials Science Poland

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2013

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tom Vol. 31, No. 3

471--475

EN

BiFeO3 polycrystalline ceramics was prepared by solid-state reaction method and its structural, optical and magnetic properties were investigated. BiFeO3 was synthesized in a wide range of temperature (825 – 880 °C) and a well crystalline phase was obtained at a sintering temperature of 870 °C. X-ray diffraction patterns of the samples were recorded and analyzed for the confirmation of crystal structure and the determination of the lattice parameters. The average grain size of the samples was found to be between 1 – 2 μm. The determined value of direct bandgap of BiFeO3 ceramics was found to be 2.72 eV. The linear behavior of M-H curve at room temperature confirmed antiferromagetic properties of the BiFeO3 (BFO). S shaped M-H curve was obtained at a temperature of 5 K. In the whole temperature measurement range (5 – 300 K) of M-T, no anomalies were observed due to high Curie temperature and Neel temperature of the BiFeO3.

4

Frequency and temperature dependence of dielectric and electric properties of Ba2-xSm4+2x/3Ti8O24 with structural analysis

80%

Narang S. B. , Kaur D. , Pubby K.

Materials Science Poland

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2015

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tom Vol. 33, No. 2

268--277

EN

Dielectric ceramics samples of barium titanium oxide doped with samarium, having a complex structural formula of Ba2-xSm4+2x/3Ti8O24 (referred to as BST), were fabricated by a high temperature solid-state reaction technique with varying x (0.0, 0.2, 0.4, 0.6). X-ray diffraction technique was used to check the formation of particular phases. Scanning electron microscope technique was used to study the surface morphology of the samples. The samples were studied in a temperature range of 298 K to 623 K and frequency range of 10 KHz to 1 MHz. The dielectric constant (εr), loss tangent (tanδ), and AC conductivity (σAC) were measured on sintered disks of BST samples. The DC resistivity of different compositions was measured at room temperature. Detailed studies of dielectric and electrical properties showed that these properties are strongly dependent on composition, frequency and temperature. The compounds showed stable behavior in lower temperature range (up to 523 K), therefore, they can be used in practical applications in this temperature range.

5

Characterization of laser ablated AgInSe2 films

80%

Pathak D. , Bedi R. K. , Kaur D.

Materials Science Poland

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2010

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tom Vol. 28, No. 1

199--205

EN

AgInSe2 (AIS) thin films have been grown directly on silicon by means of a pulsed laser deposition technique. The X-ray diffraction studies show that the films are textured in the (112) direction. Increase of the substrate temperature results in a more ordered structure. Composition of the samples has been analysed by EDAX. It was found that the stoichiometry is better maintained with the PLD technique than with other traditional methods like thermal evaporation. The optical studies of the films show that the optical band gap is about 1.20 eV. The results of investigations may be of interest for a better understanding of the growth processes of chalcopyrite thin films on silicon materials.

6

Gregarina alphitobii sp. n. and Mattesia alphitobii sp. n., parasitizing Alphitobius diaperinus Panz. (Tenebrionidae, Coleoptera)

80%

Bala P. , Kaur D. , Lipa J. J. , Bhagat R. C.

Acta Protozoologica

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1990

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tom 29

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nr 3

7