47,963 research outputs found
The Forman Christian College Monthly
No full textEwing NumberBatra, P. N.-Leading Editorial. pp. 2-3; Griswold, H. D.-Dr. Ewing's Life and Work in India. pp. 3-5; Farewell Address to Dr. J. C. R. Ewing. pp. 5-9; Wadhawa Ram-Figures I Move Among. pp. 9-11; Harbans Lall Datt-Essay-Poetry. pp. 11-12; Vir Bhan Kathuria-To the Freshers. pp. 13-14; Wit and Humour. pp. 14-17; Prem Sukh-Poetry-Riddles. pp. 18; Bhatty, M. S.-A Memorable Parting. pp. 19; Bhatty, M. S.-An Election Tournament. pp. 19-20; Batra, P. N.-Athletics. pp. 20-21; Fazal, C.-Exchanges. pp. 21-22; Book Reviews. pp. 22-24Rev. J. C. R. Ewing, Principal Emeritus and formerly Vice-Chancellor of the Punjab University. before content
Modelling and Simulation of Acoustic Wave Propagation in Locally Resonant Sonic Materials
No full textParallel Processing Simulations of the Propagation of Ultrasonic Waves through Material Interfaces
No full textA Spring model for Perfect or Imperfect Contact Interfaces
No full textA spring model for the simulation of the propagation of ultrasonic pulses through perfect or imperfect interfaces is proposed in the framework of the local interaction simulation approach (LISA). To demonstrate the applicability of the technique (which is particularly suitable for parallel processing) a few examples of numerical simulation of pulse propagation through interfaces with a delamination are presented and discussed
Isaac Lampronti. —פחד יצחק Mahadura Qama u-Batra. Éditeur : Samuel Achkenazi. Tome I (אא-אטרוחי בי דינא), Jérusalem, 1962
No full textSchwarzfuchs Simon. Isaac Lampronti. —פחד יצחק Mahadura Qama u-Batra. Éditeur : Samuel Achkenazi. Tome I (אא-אטרוחי בי דינא), Jérusalem, 1962. In: Revue des études juives, tome 122, n°3-4, juillet-décembre 1963. p. 471
Simulation of Ultrasound Propagation across Interfaces with Imperfect Contact
Full text linkIn elastic materials the propagation of ultrasonic waves is governed by the Christoffers equation, which relates the displacement vector as a function of time and position to the stiffness tensor at that point. If the material is inhomogeneous, an analytical solution of the partial differential equation becomes exceedingly difficult or impossible, especially in the presence of non-trivial boundary or initial conditions. Finite Difference Equations (FDE) provide a very convenient tool for the solution of partial differential equations (PDE’s) in media, in which the physical properties are homogeneous or vary continuously, such as Epstein Layers. Otherwise the use of FDE’s may be justified only as an approximation. In fact, for the conversion of derivatives into finite differences, a “smoothing” of the variables across the interfaces is required and, if the discontinuity is sharp, severe errors or ambiguities may result [1,2].</p
First records of the myrmecophilous fungus Laboulbenia camponoti Batra (Ascomycetes: Laboulbeniales) from the Carpathian Basin
No full textLaboulbenia camponoti Batra, 1963 (Ascomycetes: Laboulbeniales), has been found on Camponotus aethiops (Latreille, 1798) (Hymenoptera: Formicidae) workers in the Carpathian Basin: in Baziaş, Caraş-Severin (Romania), and Vienna (Austria). Vienna is the northernmost known locality of this fungus (48°12' N). These new observations expand the area of L. camponoti from regions with Mediterranean and subtropical climatic influences to the common borders of the Continental and Pannonian regions. These results show that Camponotus samples from other climatic regions should be examined more closely for this fungal parasite
p-n Junction Formation in i-Ge Crystal by Laser Radiation
No full textP-n junction is the main component of many semiconductor devices. Thermodiffusion, ion implantation and molecular beam epitaxy are only a few methods to form a p-n junction. The main drawback for these methods is high cost per p-n junction since the equipment for these methods is expensive. A possibility of p-n junction formation by laser radiation was shown in several p- and n-type semiconductors: p-Si[1,2], p-CdTe[3], p-InSb[4,5], p-InAs[6], p-PbSe[7] and p-Ge[8] due to inversion of conductivity type. Unfortunately, the mechanism of p-n junction formation by laser radiation is not clear until now.
In the present research rectification effect of current-voltage characteristic in pure intrinsic Ge crystal after irradiation by Nd:YAG laser was observed. The effect is characterised by threshold intensity of the laser radiation. Increase of rectification ratio of current-voltage characteristics and barrier height with intensity of the laser radiation, energy of laser radiation quanta and number of pulses was observed in this experiment. The mechanism of this phenomenon is explained by generation and redistribution of intrinsic point defects in temperature gradient field, which causes strongly absorbed laser radiation. The redistribution of defects takes place because interstitial atoms drift towards the irradiated surface, but vacancies drift in the opposite direction – in the bulk of semiconductor according to Thermogradient effect. Since interstitials in Ge crystal are of n-type and vacancies are known to be of p-type, a p-n junction is formed.
[1] Y. Mada et al. Appl. Phys. Lett., 48, pp. 1205 (1986).
[2] J. Blums et al. Physics Status Solidi (a), K91, (1995).
[3] A. Medvid’ et al., Radiat. Meas., 33, 725 (2001).
[4] I. Fujisawa, Jap., J. Appl. Phys, 19, 2137 (1980).
[5] A. Medvid‘ et al. Vacuum, 51, 245 (1998).
[6] L. Kurbatov et al. Reports of Acad. Sc.USSR, 268, 594 (1983)
[7] K.D. Tovstyuk et al. Ukrainian Journal of Physics, 21, 1918 (1984).
[8] S.G. Kiyak et al. Physics and Technics of Semiconductors, 18, 1958 (1984).
Acknowledgments.
The author gratefully acknowledges financial support in part by Europe Project in the Framework of MATERA+ project, European Regional Development Fund within the project “Sol-gel and laser technologies for the development of nanostructures and barrier structures”, the ESF Projects No. 1DP/1.1.1.2.0/09/ APIA/VIAA/142 and «Support for the implementation of doctoral studies at Riga Technical University»
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