001246   Singh P;Goel T C (Department of Physics, Indian Institute of Technology, New Delhi) : Dielectric constant, permeability and microwave absorption studies of ba-NiTi hexaferrite composites in X-band. Indian J pure appl Phys 2000, 38(3), 213-19.

Effect of Ni²⁺Ti⁴⁺ substitution on complex permeability and permitivity and microwave absorption has been studied for Ba(NiTi)xFe12-2xO19 hexaferrite-epoxy composites, wherein x varies from 0.0 to 1.0 in steps of 0.2, in the frequency range 8.0-12.4 GHz. The hexaferrite-composites with x Δ 0.6 exhibit significant dispersion in the complex permittivity (ε'jε") with maximum value of ε" is observed for x equal to 0.6. The dispersion in the complex permeability (μ'-jμ") is not significant which is attributed to the reduced interaction between crystallises of ferrites and low alternating electromagnetic field applied to the sample. The variation of reflection loss has been studied as a function of frequency (f), Ni^{2+,D>Ti4+ Content (x) and thickness of the absorber (d). The minimum reflection loss of -30.0 dB is obtained for composites with x equal to 0.06 and absorber thickness of 2.75 mm. The experimental values of the matching frequency and the matching thickness agree well with the theoretical values obtained by solving the equations numerically.}

7 illus, 12 ref

001245   Singh N P;Singh A K (Department of Mathematics, CL Jain (PG) College, Firozabad-283 203) : MHD effects on heat and mass transfer in flow of a viscous with induced magnetic field. Indian J pure appl Phys 2000, 38(3), 182-9.

Study is concerned with flow of an incompressible electrically conducting viscous fluid past a steady moving semi-infinite vertical porous plate under the action of uniform transverse magnetic field taking into account the induced magnetic field and constant heat flux. The analytical solutions for velocity field, temperature distribution, induced magnetic field, current density, concentration field and the expressions for shear stress and rate of heat transfer are obtained and discussed in detail.

6 illus, 1 table, 15 ref

001244   Singh N P;Gupta S K;Singh A K (Department of Mathematics, C.L. Jain College, Firozabad-283 203) : MHD free convection and mass transfer in dusty flow of a rotating viscous liquid. Indian J Theor Phys 2000, 48(2), 161-70.

Free convection and mass transfer in the flow of an electrically conducting, incompressible, viscous rotating liquid past a vertical porous plate in porous medium embedded with non-conducting, solid, spherical and uniformly distributed dust particles has been studied. It has been observed that when the Schmidt number increases the concentration of species and the mass transfer decrease besides the heat transfer and temperature profiles, decreases exponentially with time.

4 tables, 15 ref

001243   Singh J B;Singh R K (Department of Mathematics, S.G.R.P.G. College, Dobhi, Jaunpur) : Self-similar flows behind strong cylindrical shockwave. Indian J Theor Phys 1999, 47(3), 243-52.

Similarity solutions for unsteady flow of a perfect gas behind a strong cylindrical shockwave are investigated in the presence of azimuthal magnetic field. The flow is caused by an expanding cylindrical piston and the total energy of the flow increases with time obeying a power law.

4 illus, 6 ref

001242   Singh A K;Narendra Kumar;Singh N P;Ranvir Singh (Department of Mathematics, V.S.S.D. College, Kanpur-208 002) : Temperature field in MHD flow of a viscous incompressible fluid through an inclined open rectangular channel with a bed of varying permeability. Indian J Theor Phys 1999, 47(4), 273-83.

Deals with the study of temperature field in MHD flow of an electrically conducting viscous incompressible fluid through an inclined open rectangular channel with varying permeable bed. An exact solution for velocity and temperature of fluid in slip flow regime has been obtained using finite Fourier sine transform. The effect of Eckert number and Prandtl number of magnetic and non-magnetic cases at given values of other parameters has been discussed with the help of graphs.

2 illus, 8 ref

001241   Shah R C;Verma A P (Department of Applied Sciences, VVP Engineering College, Kalavad Road, Virda Vajdi, PB No. 95, Rajkot-360 005) : Multiphase flow through slightly dipping porous media with magnetic fluid. Indian J pure appl Phys 2000, 38(3), 166-9.

Instabilities which arise in the displacement process involving two immiscible liquid through homogeneous porous media with magnetic fluid is numerically discussed under some suitable set of initial and boundary conditions. This type of problem appears particularly in petroleum technology and hydrogeology.

4 illus, 1 table, 6 ref

001240   Sengupta S;Das S C;Acharya D P;Sengupta P R (NO, Indian Institute of Mechanics of Continua, 201, Manicktala Main Road, Suite No. 42, Calcutta-700 054) : Plane Lamb's problem in an inhomogeneous medium under gravity. Indian J Theor Phys 2000, 48(3), 231-40.

Longitudinal and transverse wave propagation in an isotropic and non-homogeneous semi-space bounded by a plane in which some loading is applied under the influence of gravity has been studied. Loading harmonic in time is also considered as a particular case in this problem.

17 ref

001239   Sengupta P R;Rahaman B;Kandar D K (Department of Mathematics, University of Kalyani, Kalyani-741 235) : MHD flow of visco-elastic fluid down an inclined plane. Indian J Theor Phys 2000, 48(2), 171-7.

Attempt has been made to investigate the hydromagentic flow of visco-elastic Rivlin-Ericksen fluid flowing down an inclined plane. Using the Rheological equations of such a visco-elastic fluid, the analytical solution of the velocity has been obtained firstly as a function of a space co-ordinate and time by variable seperation technique. The solution has been obtained in a closed and simple form. Moreover, the numerical computation of the velocity component has been derived in the form of table and graph and the corresponding velocity profile has been exhibited. A discussion has been presented at the end to explore the nature of the flow of the fluid.

1 illus, 1 table, 22 ref

001238   Sengupta A K;Chakraborty H S;Ghosh K (Dept. of Mathematics, Jadavpur University, Calcutta-700 032) : Stress and displacement in a clamped heterogeneous circular cylinder due to a couple at the other end. Indian J Theor Phys 2000, 48(2), 141-7.

Torsion problem of a non-homogeneous isotropic circular cylindrical thick shell acted upon by a torque at one end, the other end being fixed is considered here. The solution is presented in series form under the supposition that the prescribed torque is expressible as a function of the radius in Dini series. For linear distribution of applied shearing forces over the entire terminal section of the shell, the stresses and displacements are obtained in closed forms. Results for the homogeneous cylindrical shellare derived as a particular case.

4 ref

001237   Sen A K;Bera R;Mitra A (NO, Institute of Radio Physics and Electronics, University of Calcutta, 92, A P C Road, Kolkata-700 009) : Millimeterwave CW Doppler radar for vibration remote sensing. Indian J Phys-Pt B 2001, 75(3), 267-8.

Doppler radar sensors have been heavily utilized at millimeter wavelengths. They are currently in use for a variety of applications including commercial and industrial uses in level sensing, motion detection, speed measurement and collision warning sensors. Their relative simplicity and low cost production potential make them attractive for these applications. A millimeter wave Doppler radar development is described with the off-line DSP techniques to convert the time to frequency conversion from which the velocity of the moving target can be predicted. A simple experimental set up has been described where a vibrating metal reed is used as vibrating object. One application area of the 94 GHz Doppler radar for the measurement of rain drop size distribution is highlighted.

2 illus, 2 ref

001236   Sen A K;Bera R;Mitra A (NO, Institute of Radiophysics and Electronics, 92, A P C Road, Kolkata-700 009) : Shift of conventional millimeterwave window with variation of atmospheric parameters and applications. Indian J Phys-Pt B 2001, 75(3), 239-40.

Atmospheric constituents oxygen and water vapour mainly controls the clear air absorption of millimeter waves. Both of these constituents have certain resonance absorption frequencies. In between the resonance frequencies of O2 and H2O contents of atmosphere there are certain window frequencies where the absorption of millimeter waves are minimal. All round the World Scientists, technologists, Industrialists and users of millimeterwave communication Radar and Remote Sensors presume the millimeterwave window frequencies at 35, 94, 140 and 220 GHz, to utilize the lowest atmospheric attenuation and lowest equivalent thermal emission noise at the window frequencies. However, the window frequencies are subject to shift with variations of the atmospheric water vapour content and temperature. Studies the millimeterwave window shift by using the theoretical Liebe model, which is the best one of the variety of theoretical models. The estimates of atmospheric windows for the Tropical regions in India and subsequently estimates the window frequencies in the temperate regions of the World, finding that the conventional window frequencies is shifted down sufficiently in tropical region countries.

2 tables, 3 ref

001235   Satish Kumar;Dixit R P (NO, Defence Electronics Applications Laboratory, Raipur Road, Dehradun-248 001) : Waveguide T junction circulator at Ka-band. Indian J Phys-Pt B 2001, 75(3), 215-16.

Even though design aspects of circulators have been described in detail by many authors, there was still a need to evolve a simple and direct approach by examining various advantages and disadvantages of these methods. Gives the practical performance of circulators designed at Ka-band of frequencies adopting the methodology described.

2 illus, 5 ref

001234   Sarkar S K;Karmakar A;De A K (Department of Electronics and Telecommunication Engineering, Jadavpur University, Calcutta-700 032) : Magneto-quantum effects on microwave and millimeterwave response of two-dimensional hot electrons in n-Hg_0.8 Cd_0.2 Te. Indian J Phys-Pt A 2001, 75(3), 267-9.

Small-signal microwave and millimeterwave mobilities of degenerate hot electrons moving two-dimensionally in a (Hg, Cd) Te quantum well are calculated in the framework of a heated drifted Fermi-Dirac distribution function. The electron energy loss via polar optic phonons and the momentum loss via interactions with polar optic phonons, deformation potential acoustic phonons, background ionized impurities and alloy disorder scattering are incorporated in the calculations. The small-signal mobility is found to remain fairly constant upto about 6GHz, while the drift velocity starts to lag behind the applied field from about 0.3 GHz. The 3dB cut-off frequency at which the small-signal mobility falls to 0.707 of its flow frequency value is found to increase with the lattice temperature and dc bias field.

^ssc3 illus, 8 ref

001233   Sarkar M J A;Sarkar M A R (NO, University of Rajshahi, Rajshahi-6205, Bangladesh) : Electrical conduction of amorphous SiOx thin films. Indian J pure appl Phys 2000, 38(3), 190-5.

Thin film capacitors of amorphous SiOx (0 Δ x Δ 2) thin films were fabricated by electron beam gun deposition. The current density versus voltage (J-V) characteristics of SiOx films were studied for different thickness (130-280 nm) and temperatures (300-475K). It was observed that at high electric field E Δ2.50 x 10⁷ Vm<6>-1, the current density increases linearly with square root of the electric field (E^1/2). The conduction mechanism in these films appear to be predominated by the Poole-Frenkel emission. The variations of activation energy with applied fixed voltages and temperatures were investigated and the results are discussed.

7 illus, 4 tables, 27 ref

001232   Sanyal S;Gangopadhyay S;Sarkar S N (Fiber Optics Research Group, Department of Electronic Science, University of Calcutta, 92, A P C Road, Kolkata-700 009) : Single-mode graded index fiber directional coupler : analysis by a simple and accurate method. Indian J Phys-Pt B 2001, 75(3), 235-7.

Presents simple and accurate analysis of coupling characteristics of identical single-mode graded index fiber directional couplers. Based on the recently developed simple series expression for the fundamental mode of such a fiber involving Chebyshev technique. Analytical expressions of the relevant parameters are presented and the concerned calculations are executable with much less computations. With examples of step and parabolic index fiber directional couplers it shows that estimations match excellently with the exact results.

2 illus, 11 ref

001231   Sanyal D C;Mallik M B (Department of Mathematics, University of Kalyani, Kalyani-741 235) : SH-waves in a poroelastic layer over a semi-infinite elastic medium due to irregularity on the interface. Indian J Theor Phys 1999, 47(4), 47-56.

The propagation of simple harmonic waves in a homogeneous isotropic poroelastic layer lying over a semi-infinite elastic medium due to irregularity in the crustal layer has been considered. The dispersion equation has been obtained in which the effect of poroelasticity is distinctly marked.

1 illus, 15 ref

001230   Sanandiya H C;Mahajan M B;Ghai V A;Arun Kumar (NO, Space Applications Centre, ISRO, Ahmedabad-380 053) : Compact antenna system for dual beam application in GSAT-1 satellite. Indian J Phys-Pt B 2001, 75(3), 195-9.

Indigenously developed Geo-Stationary Launch Vehicle (GSLV) will launch GSAT-1 communication satellite. The antenna is catering uplink service for two different coverages : Indian region and South African countries. The antenna configuration is 0.4 m single offset reflector antenna with two feed horns system. The frequency band of operation is 5.850-6.370 GHz with gain requirement of 21 dBi over the very wide two separate coverage of the order of 8.0°. Deals with the design and analysis considering various factors such as EOC gain requirement over the dual wide coverages, with constraint of volume and feed inter-element spacing, focal length to reflector diameter ratio (fld), offset angle, offset distance. The scope is limited to dual coverage antenna design and analysis, where a single offset parabolic is used as an aperture.

9 illus, 1 table, 4 ref

001229   Sahu S N;Nanda K K (NO, Institute of Physics, Bhubaneswar-751 005) : Nanostructure semiconductors: physics and applications. Proc Indian Natn Sci Acad-Pt A 2001, 67(1), 103-30.

Semiconductor nanostructures with size in few nanometer range and comparable to Bohr exciton radius show quantum size effect (QSE). The consequence of QSE leads to discretisation of energy bands and results in widening of the band gap. Large surface to volume ratio and QSE in nanostructure semiconductors give rise to some of the unique semiconducting properties that are not normally found with bulk semiconductors. Describes some preparatory techniques to synthesize nanostructure semiconductors in particulate and thin film form. Composition, surface roughness, thickness, Structure, crystalline size, shape and thermodynamic properties often influencing the nanostructure properties are discussed with theoretical back ground and experimental results. Optical absorption, photoluminescence and Raman measurements demonstrate QSE, trap effect and size dependent properties. Finally, electrical, interfacial/device properties, stabilty and device applications of nanostructure semiconductors have been discussed.

21 illus, 1 table, 161 ref

001228   Roy S K (Department of Physics, Government Polytechnic, Darbhanga-846 004) : Study of the resonant frequency of the equilateral triangular microstrip patch antenna. Indian J Theor Phys 2000, 48(3), 225-30.

Study of the resonant frequency of the equilateral triangular microstrip patch antenna is presented. The region between the microstrip patch and the ground plane can be treated as a cavity bounded by magnetic walls along the edges and by electric walls from above and below. A cavity model analysis is used in conjunction with this formula to obtain the resonant frequency of the Equilateral Triangular Microstrip Patch Antenna. Accuracy of the theoretical results of resonance is compared with previous theories and measured data.

1 illus, 1 table, 9 ref

001227   Ramasamy S;Purniah B (Department of Nuclear Physics, University of Madras, Guindy Campus, Chennai-600 025) : Electrical properties of nanostructured materials. Proc Indian Natn Sci Acad-Pt A 2001, 67(1), 85-102.

The electrical conductivity in a polycrystalline material is the sum of the carrier transport under the applied field, in the grains and along/across the grain boundaries. The electrical conductivity can be studied by applying a d.c. voltage. However, if one is interested to investigate the dielectric property also, an a.c. voltage has to be applied and the variation of the impedance as a function of frquency must be measured. This gives in turn, both the a.c. conductivity and d.c. conductivity. Metals and alloys do not have capacitative and inductive components. Hence the resistivity or the conductivity, is studied by applying a d.c. voltage. Ceramics and composites have capacitative components and hence the second method namely the impedance spectroscopy is often employed to investigate the electronic and ionic transport properties of these materials. In this article, under the heading impedance spectroscopy, the dielectric properties of nanostructured ceramics and composites will be reviewed; under the heading d.c. electrical conductivity, electrical conductivity of nanostructured metals, alloys, ceramics and composites will be reviewed. The role of grain boundary scattering of charge carriers is an important factor in the study of transport properties. Transport properties include diffusion, Hall effect and thermoelectric power also.

19 illus, 1 table, 81 ref

001226   Ramakoteswara Rao G V;Ghosh A;Borkar V G (NO, Research Centre Imarat, Hyderabad-500 069) : Design and development of cassegrain antenna with wide and narrow coverage. Indian J Phys-Pt B 2001, 75(3), 163-5.

Single antenna that can realize the performance of contradictory requirements of wide and narrow coverage over a band of frequency is to be designed. A novel technique of axial defocused cassegrain antenna system is presented with wide and narrow beam coverage. Antenna fabrication and testing is presented. A comparison of simulated and tested results is also presented.

4 illus, 7 ref

001225   Radhi R A;Taqi A H;Ahmad A K (Department of Physics, College of Science, University of Baghdad, Baghdad, Iraq, ) : Random phase approximation with high orbits configuration for the low lying negative parity, T + 0 states in <. Indian J Phys-Pt A 2001, 75(3), 255-8.

Electroexcitations of the dominantly low-lying T = O. negative parity, particle-hole states of ¹⁶O are studied in the framework of the random phase approximation (RPA). These states include states with J^π (E_x MeV) : 1^-(7.12), 3^- (6.13) and 4^- (17.79). All possible single T = O particle hole states of allowed angular momenta, for both ground states and excited states are considered in bases including single-particle states up to the 1f 2p shell. The Hamiltonian is diagonalized in this extended space in the presence of the modified surface delta interaction (MSDI). Admixture of higher configurations is considered for the ground state to allow for a large scale of a collective motion in the nucleus. Effective operators are used to account for the core polarization effect.

4 illus, 12 ref

001224   Radhi R A;Elawi M A;Dakhiil Z A (Department of Physics, College of Science, University of Baghdad, Jadiriyah, P.O. Box 47138, Baghdad, Iraq) : Elastic magnetic electron scattering from <. Indian J Theor Phys 2000, 48(3), 193-200.

Form factors for elastic magnetic electron scattering from ¹⁹F has been calculated using an extended model space wave function. The wave function included in this case mixing of the model space wave function defined by the orbits 2s-1d with a higher configuration defined by the orbits 3s-2d. The inclusion of a higher configuration with the model space configuration produces a second maximum which was found experimentally. The high momentum transfer data are sensitive to the size parameter of the harmonic oscillator potential used to generate the single particle wave functions, and the data are well described when the size parameter is reduced from that to fit the measured root mean sequare charge radius.

4 illus, 13 ref

001223   Puri V;Sathe M;Siddiqui A (Thick and Thin Film Device Laboratory, Department of Physics, Shivaji University, Kolhapur-416 004) : Ferrite loading effects on electromagnetically coupled patch antenna. Indian J Phys-Pt B 2001, 75(3), 175-7.

Composition and thickness dependent effects due to ferrite loading (overlay) on electromagnetically coupled rectangular patch antenna is reported. The effect of variation in feed position is also studied. The long side feed and diagonal feed positions show different behaviour due to ferrite loading as compared to short side feeding position. The resonance frequency decreases and peak transmittance increases dramatically due to ferrite pellet overlay.

2 illus, 1 table, 2 ref

001222   Prevenslik T V (NO, , 2E Greenery Court, Discovery Bav, Hong Kong) : On the possibility of a cavity QED cold fusion cell. Indian J pure appl Phys 2000, 38(3), 155-7.

Sonoluminescence (SL) in ultrasonic cavitation may be described by the emission of photons and electrons from the collapse of bubbles in liquid H2O in the Planck theory of SL, the bubbles are treated as collapsing masers containing electromagnetic (EM) radiation. By this theory, the SL source is the EM radiation that corresponds to the absorption (and emission) spectra of the liquid H2O bubble wall over the frequency range from the UV to soft X-rays. As the maser collapse, the resonant frequency of the maser always increases. If the maser resonance coincides with the EM emission spectra of the liquid H2O wall, cavity QED induces the EM radiation at the frequency to be spontaneously emitted within the master. But spontaneous EM emission at frequencies lower than the maser resonance is inhibited. SL electrons and photons are created from the inhibited spontaneous EM emission by the stokes shift, or the photoelectric effect or by the microwaves generated as the bubble collapse. The amount of Planck energy available in bubble collapse far exceeds that necessary for SL. Indeed, the planck energy available from the focussing of EM radiation into a microscopic cavity during the ultrasonic cavitation of D2O containing D2 containig D2 gas is sufficient for a limited number of cold fusion events fusion events. However, cold fusion in the Planck theory of SL is not limited to the ultrasonic cavitation of bubbles in liquid D2o.

2 illus, 8 ref

001221   Podlaha M F (NO, , D-94089, Neureichenau, Germany) : Basic laws of vacuum field. Indian J Theor Phys 1999, 47(4), 265-71.

Basic notions of physics: matter, rest mass bodies, radiation and fields are discussed. The discovery of K.C. Kar that photons have a mass is emhasized. Physical space is not empty. It contains the universal vacuum field. Universality of physical fields is discussed. Energetical content of rest mass bodies increses with increasing refraction index of the vaccum field. Anisotropy of the lengths of matter waves of the first kind is analysed.

7 ref

001220   Panda S;Panda B K (NO, Institute of Physics, Sachivalaya Marg, Bhubaneswar-751 005) : Analytic methods for field reduced tunneling in quantum wells with arbitrary potential profiles. Pramana J Phys 2001, 56(6), 809-22.

Electric field induced tunneling is studied in three different types of quantum wells by solving time-independent effective mass equation in analytic methods based on three different Airy function approaches. Comparison of different Airy function methods indicates that they are identical and connected to each other by the Breit-Wigner formula.

3 illus, 3 tables, 37 ref

001219   Pal A;Bera R K (NO, Saraswati Balika Vidyalaya and Shilpa Siksha Sadan, 27/2P, Balaram Ghosh Street, Calcutta-700 004) : New approach on large deflection analysis of spherical sandwich shell. Indian J Theor Phys 1999, 47(3), 189-202.

In the present analysis the non-linear static and dynamic behaviour of spherical sandwich shell due to large deflection have been studied by a new set of decoupled differential equations. Numerical results for different types of loading have been computed and compared with other known results.

2 illus, 15 ref

001218   Orisa B D (Department of Mathematics, Moi University, Eldoret, Kenya) : Plane pendulum in quantum mechanics. Indian J Theor Phys 2000, 48(3), 241-54.

An exact solution of Schroedinger's equation for the plane pendulum is obtained. The compact solution enables an examination of the motion of the system on the basis of the probability concept of quantum theory.

3 illus, 7 ref

001217   Nath M (NO, SAMEER, Ministry of Information and Technology, Plot-L2, Block GP, Sector-V, Salt Lake Electronics Complex, Calcutta-700 091) : Development of microstrip antenna array for monopulse application. Indian J Phys-Pt B 2001, 75(3), 201-03.

Radiation and impedance properties of a microstrip patch antenna array have been investigated experimentally. The antenna structure consist of four cornerfed square patch array which are arranged properly to fit four quadrants of a circle. This type of configuration is choosen to use it with monopulse comparator. The antenna is matched with its feed line by impedance transformer. Experimentally observed results are comparable to that obtained theoretically.

4 illus, 6 ref

001216   Naithani U C;Panwar N S;Semwal B S (Department of Physics, HNB Garhwal University Campus Pauri, Pauri (Garhwal)-246 001) : Electric field dependence of microwave losses in strontium titanate. Indian J pure appl Phys 2000, 38(3), 196-201.

Electric field dependent microwave losses in pure single strontium titanate crystal have been theoretically calculated at microwave frequency 5 GHz. The loss tangent consists of a contribution, which is quadratic in applied biasing plus a field independent contribution. This variation of tan δ with applied field is noticeable in the vicinity of the Curie temperature. In the high temperature region the field's effect ceases and the increase in loss arises mainly due to higher order anharmonic terms.

1 illus, 22 ref

001215   Naik P A;Sharma A K (Plasma Radiation Section, Centre for Advanced Technology, , Indore-452 013) : Calculation of higher order group velocity dispersion in a grating pulse stretcher/compressor using recursion method. J Optics 2000, 29(3), 105-13.

Sub-picosecond Table Top Terawatt laser systems, grating based stretcher and compressor are used for chirped pulse amplification. For such a compressor/stretcher, the analytical expression for the higher order group velocity dispersion (GVD) is obtained using Taylor series method, which involves higher order differentiation. Starting with the same method, derive here a recursion relation for higher order GVD terms, which eliminates the need of explicit differentiation.

3 table, 19 ref

001214   Mukhopadhyay T K;Kundu K K;Das N C (Department of Mathematics, Nimichi R. N. Vidyalaya, P.O. Nimichi, Basirhat, Dist-24 Paraganas-743 456) : Dynamical problem in a composite piezo-quartz transducer partly subjected to a flow of current under a polarisation gradient. Indian J Theor Phys 2000, 48(2), 133-40.

Mechanical behaviour of a composite piezo-quartz transducer partly subjected to a flow of current in the semi-conducting boundary layer under a polarisation gradient for impulsive input signal has been investigated. The equations of electricity and the relevant constitutive equations of piezo-electric material have been used and finally the solution has been obtained with the aid of operational calculus. For time-scale ranging from 0 to 1s, the mechanical disturbance exhibits an arc of a parabola but interestingly a constant disturbance of the order of 10¹⁵m persists at t=0.

2 illus, 1 table, 14 ref

001213   Mukhopadhyay T K;Kundu K K;Das N C (Department of Mathematics, Nimichi R N Vidyalaya, Nimichi, Basirhat-743 456) : On a problem of mechanical response in a composite piezoelectric transducer subjected to a semi-conducting boundary layer. Appl Sci Period 2001, 3(2), 113-19.

Investigates the mechanical response in a composite piezo-quartz transducer, hardbacked on both ends, driven by a current flow in the semi conducting boundary layer. The method of operational Calculus has been used to solve the problem using a simplified one dimensional approach and numerical results are presented. For time-scale ranging from 0 to 1S, the mechanical disturbance exhibits a rectangular hyperbola but interestingly a constant disturbance of the order of 10^-8 m persists at t=0.

2 illus, 3 tables, 10 ref

001212   Misra U D;Chaturvedi S (Physics Department, Lucknow University, Lucknow-226 007) : A new method for the calculation of Sommerfeld screening parameter σ1 in x-ray spectra. Pramana J Phys 2001, 56(6), 745-54.

Describes a new method for the calculation of the Sommerfeld screening parameters σ1. It requires neither the knowledge of the energy separations of spin doublet levels nor is it based on the application of the Hertz law. The only data required for the calculation are the experimental energy values of the level concerned for the series of elements belonging to the same subshell in which the element in the question is situated. As an illustration the values of σ1 are calculated for the L1, L2 and L3 levels for elements belonging to the 4f subshell and these are found to be in excellent agreement with those published earlier by Gokhale and Misra. The method brings out the constancy of σ1(L2<60>V3)-<115> 1 (L1) in a natural way and may thus be regarded as providing theoretical explanation of the Hertz law.

3 tables, 22 ref

001211   Mahajan P N (Forecasting Research Division, Indian Institute of Tropical Meterology, Pune-411 008) : Better analysis and depiction of monsoon systems through satellite microwave remote sensing. Indian J Phys-Pt B 2001, 75(3), 263-5.

Various algorithms developed by global community have been applied to DMSP-SSM/I data. Those algorithms which were found most suitable and appropriate have been used for the analysis and proper depiction of monsoon systems over the Indian region. It is found that prior to the formation the monsoon depressions, there was strengthening of surface wind speed to the south of the low pressure area. This wind speed was of the order of 12-15 ms^-1. The strengthening of wind speed was in association with the low-level jet present over that region. Higher values of integrated water vapour (60-70 kg m^-2) were observed over the central and head Bay throughout the life cycle of monsoon depression. Highest values of integrated cloud liquid water (0.7 kg m^-2) were found to be associated with major convective activity in the southwest sector of the monsoon depression. Windspread precipitation (2-16 mm hr^-1) was found to be associated with low pressure system over the northwest Bay and the precipitation was further found to be concentrated more in the southwest sector of the monsoon depression with maximum precipitation rates of the order of <62>20 mm hr^-1. Results of studies suggest that estimated geophysical parameters obtained from SSM/I data can be used with some confidence as an input to various weather forecast models.

1 illus, 19 ref

001210   Livingsta A D Q;Mary Jeeva T;Mahadevan C; Balasingh C (Department of Physics, Scott Christian College, Nagercoil-629 003) : Lattice variation and thermal parameters of KDP crystals added with urea and NiSO₄.7H₂O. Indian J Phys-Pt A 2001, 75(3), 241-4.

Pure and impurity added (with urea and NiSO₄.7H₂O) KDP single crystals were grown by the slow evaporation method from aqueous solutions. Density was measured by the floatation method. X-ray diffraction data were collected for powder samples and used for the estimation of lattice variation and thermal parameters like Debye-Waller factor, mean - square amplitude of vibration, Debye temperature and Debye frequency. No serious lattice distortion was observed due to impurity addition. The thermal parameters do not vary in a particular order with respect to impurity concentration.

2 tables, 30 ref

001209   Lahiri P;Bhattacharya A;Mondal D;Biswas B N (Radionics Laboratory, Physics Department, Burdwan University, Burdwan-713 104) : Rectangular active microstrip patch antennas : few experimental observations. Indian J Phys-Pt B 2001, 75(3), 179-82.

Gives an experimental verification of a recent work by the authors to verify the location of the active device on the microstrip patch antenna for the highest possible radiated power. At the patch design frequency location (l1) of the device on the patch has been found theoretically for the highest possible radiated power by considering a modified transmisssion line model and device-antenna non-linear interaction. Experimental results show very good agreement with theory. Patches are designed at two frequencies of 9.5 GHz and 9.0 GHz and an X-band 50 mW Gunn diode is used as an active device. Diode placed at the desired location, power output of the active antenna is 64.0 mW and its dc-to-RF conversion efficiency is almost comparable to that of its waveguide tuned version. Due to proper matching of the device and antenna impedances, radiation pattern of the active antenna improves greatly in addition to the lowering of its cross polarisation level.

4 illus, 3 tables, 12 ref

001208   Kundu B;Jain B K (NO, Institute of Physics, Sachivalaya Marg, Bhubaneswar-751 005) : Resonance propagation in heavy-ion scattering. Pramana J Phys 2001, 56(6), 723-34.

The propagation of a resonance in the nuclear medium in proton-nucleus collisions has been modified to the case of vector boson production in heavy-ion collisions. The formalism includes coherently the contribution to the observed di-lepton production from the decay of a vector boson inside as well as outside the nuclear medium. The medium modification of the boson is incorporated through an energy dependent optical potential. The calculated invariant ρ mass distributions are presented from the ρ-meson production using optical potentials estimated within the VDM and the resonance model. The shift in the invariant mass distribution is found to be small. To achieve the mass shift (of about 200 MeV towards lower mass) as indicated in the high energy heavy-ion collision experiments, an unusually strong optically potential of about - 120 MeV is required. Also observe that, for not so heavy nuclear systems and/or for fast moving resonances, the shape, magnitude and peak position of the invariant mass distribution is substantially different if the contributions from the resonance decay inside and outside are summed-up at the amplitude level (coherently) or at the cross section level (incoherently).

7 illus, 1 table, 16 ref

001207   Krasnoholovets V (NO, Institute of Physics, National Academy of Sciences, Prospect Nauky 46, UA-03650 Kyiv 03039, Ukraine) : Nature of spin, inertia and gravity of a moving canonical particle. Indian J Theor Phys 2000, 48(2), 97-132.

It is suggested that a moving canonical particle interacts with a vacuum regarded as a "soft" cellular space.The interaction results into the emergence of elementary excitations of space-inertons-surrounding the particle. It is assumed that such a motion leads not only to the spatial oscillation of the particle along a path but to the oscillation of the particle centre-of-mass as well. This phenomenon culminating in the anisotropic pulsation of the particle is associated with the notion of spin. The particle-space interaction is treated as the origin of the matter waves which are identified with the particle inertia and inertons surrounding the moving particle are considered as carriers of its inert properties. Inertons are also identified with real carriers of the gravitational interaction and the range of the particle gravitational potential is evaluated by the inerton cloud amplitude Δ = λc/v₀, where λ is the de Broglie wavelength, c and v₀ are the velocity of light and the particle respectively. The nature of the phase transition that occurs in a quantum system when one should pass from the description based on the Schrodinger formalism to that of resting on the Dirac one is explained in detail.

3 illus, 53 ref

001206   Khanna R K;Baheti K (Plasma and Microwave Laboratory, Physics Department, Government College, Ajmer-305 001) : Relativistic nonlinearity and wave-guide propagation of rippled laser beam in plasma. Pramana J Phys 2001, 56(6), 755-66.

Investigates the self-focusing behaviour of radially symmetrical rippled Gaussian laser beam propagating in a plasma. Considering the nonlinearity to arise from relativistic phenomena and following the approach of Akhmanov et al, which is based on the WKB and paraxial-ray approximation, the self-focusing behaviour has been investigated. The effect of the position and width of the ripple on the self-focusing of laser beam has been studied for arbitrary large magnitude of nonlinearity. Results indicate that the medium behaves as an oscillatory wave-guide. The self-focusing is found to depend on the position parameter of ripple as well as on the beam width. Values of critical power has been calculated for different values of the position parameter of ripple. Effects of axially and radially inhomogeneous plasma on self-focusing behaviour have been investigated and presented.

4 illus, 19 ref

001205   Keshava S L;Gopala K;Venkataramaiah P (Department of Radiation Physics, Kidwai Memorial Institute of Oncology, Hosur Road, Bangalore-560 029) : Decay energy of <. Pramana J Phys 2001, 56(6), 735-44.

Several measurements of decay energy using the inner Bremsstrahlung spectrum (IB) due to radiative electron capture in ⁵⁵Fe has been made. Experimental data was obtained with a 4.445 cm. dia x 5.08 cm thick NaI (TI) detector. It was subjected to suitable statistical treatment and various corrections using Liden and Starfelt procedure. The corrected spectrum agrees well with the Glauber and Martin theory for 1s electron capture beyond 100 keV. From the Jauch plot, the decay energy of 232.36±0.64 keV was obtained.

7 illus, 19 ref

001204   Johari R;Gupta G D (Department of Post Graduate Studies and Research in Mathematics, Ganjdundwara (P.G.) College, Ganjdundwara (ETAH)-207 242) : MHD free convective slip flow of viscous fluid saturated porous layer bounded by a porous plate. Indian J Theor Phys 2000, 48(2), 179-88.

Problem of unsteady two dimensional free convective magnetohydrodynamic flow of a viscous fluid through a porous medium bounded by a vertical infinite porous plate of constant temperature with slip on the plate is investigated analytically. The free stream velocity of the fluid vibrates about a mean constant value. It is also assumed that the fluid is absorbed with a constant velocity. The uniform flow is subjected to a transversely applied magnetic field. The magnetic Reynolds number is taken to be small enough so that induced magnetic field is neglected. The mathematical analysis is presented for the hydromagnetic boundary layer flow neglecting the hall effect, electrical and polarization effects. Approximate solution for the velocity field is obtained and the effects of slip, Hartmann number (M), Permeability parameter (K), Parameter of frequency (ω), Grashof number (Gr) and Prandtl number (Pr) on the velocity field are discussed with the help of graph.

1 illus, 1 table, 13 ref

001203   Jalori H;Gwal A K (Space Science Laboratory, Institute of Physics and Electronics, Barkatullah University, Bhopal-462 026) : Role of magnetic shear on the electrostatic current driven ion-cyclotron instability in the presence of parallel electric field. Pramana J Phys 2001, 56(6), 779-84.

Recent observation and theoretical investigations have led to the significance of electrostatic ion cyclotron (EIC) waves in the electrodynamics of acceleration process. The instability is one of the fundamental of a current carrying magnetized plasma. The EIC instability has the lowest threshold current among the current driven instabilities. On the basis of local analysis where inhomogeneities like the magnetic shear and the finite width current channel, have been ignored which is prevalent in the magnetospheric environment. On the basis of non-local analysis interesting modification has been incorporated by the inclusion of magnetic shear. An analytical approach for the non-local treatment of current driven electrostatic waves in presence of parallel electric field. The growth rate is significantly influenced by the field aligned electron drift. The presence of electric field enhances the growth of EIC waves while magnetic shear stabilizes the system.

1 illus, 11 ref

001202   Ishwar Bhat S;Mohan Rao P;Avasthi D K (Department of Physics, Mangalore University, Mangalagangotri-574 199) : Dielectric properties of ammonium tartrate single crystals during swift heavy ion irradiation. J Optics 2000, 29(3), 123-9.

Ammonium tartrate (NH4)2 C4H4O6 single crystals were grown from solution by means of slow evaporation technique at room temperature. The dielectric constant ∈ and a.c. conductivity σ of the grown crystal were studied as a function of frequency variation. The crystal was irradiated by heavy ions of silver Ag⁺¹³ of 120 MeV energy with a fluence rate of 5 X 10¹¹ ions/cm²/sec using the 15 UD pelletron accelerator at Nuclear Science Centre, New Delhi. Again the parameter ∈ and σ of the crystal were studied as a function of frequency variation. The results were compared. Also the change in the refractive index of the crystal after irradiation was studied. The possibility of preparing optical wave guides in these crystals is discussed.

1 table, 14 ref

001201   Hossain I;Shelley A (Department of Physics, Shah Jalal University of Science and Technology, Sylhet, Bangladesh) : Studies on experimental features of <. Indian J Phys-Pt A 2001, 75(3), 249-53.

Few features of deep-inelastic collisions ⁷⁶Ge (635 MeV) _ ¹⁹⁸Pt have been studied using the isomer-scope. The dynamic properties of this reaction reflect the correlation of mass transfer with energy dissipation of fragment. The N/Z ratios of the populated fragments indicate that deep inelastic collisions are able to produce neutron rich nuclei and the transfer of nucleon from the composite system is a diffusion process. Investigation of isomer spin as well as mass transfer suggests that there is no correlation between them.

5 illus, 6 ref

001200   Hazra L N (Department of Applied Physics, Calcutta University, 92, Acharya Prafulla Chandra Road, Calcutta-700 009) : Binary optics : challenges and prospects. Indian J Theor Phys 1999, 47(4), 57-69.

Binary optics has opened up new frontiers in the field of optical and photonic systems. It is a diffractive optics technology that uses computer generated designs of microscopic surface relief patterns and VLSI (Very Large Scale Integration) ion etching technology used for the generation of microelectronic chips. Although binary optic equivalent of conventional optical elements have already been synthesized, yet the total replacement of the conventional lenses and prisms by their binary counterparts in practical applications is not very likely to take place. Rather, hybrid (refractive-diffractive or reflective-diffractive) combinations incorporating the best features of both types hold more promise of success. Of course, their maximum potential arises in applications involving unconventional optical elements that are either impossible or very difficult to synthesize using conventional elements alone.

5 illus, 1 table, 25 ref

001199   Gupta S;Nath P K;Sarkar B K (Society for Applied Microwave Electronics Engineering and Research, IIT Campus, Powai, Mumbai-400 076) : Microstrip miniaturised antennas. Indian J Phys-Pt B 2001, 75(3), 171-3.

Deals with the various techniques for reduction in the size of the antennas. A small microstrip patch antenna is presented. The probe-fed microstrip patch incorporates a single shorting post which significantly reduces the overall size of the antenna. Theoretical impedance behaviour and radiation characteristics of the modified patch are given.

5 illus, 6 ref

001198   Gupta S;Arun Kumar (Feed System Division, Space Applications Centre, ISRO, Ahmedabad-380 053) : Multilayer planar array radiators compatible with digital beam forming array. Indian J Phys-Pt B 2001, 75(3), 191-3.

Multilayer planar array radiators are well suited as part of a digital beam forming antenna, because they can be easily integrated, with active elements in multilayer structure. This forms the basis for futuristic highly integrated circuits to be used in terminals for satellite communication system. In these antennas feeding network should be capable to efficiently transfer the signal from radiator to the underneath RF circuit in multilayer configuration or vice-versa. 5 x 5 array of circularly polarized aperture coupled raditors is designed and developed in L-band. Feeding network to generate circular polarization is realized in tri-plate configuration. Symmetric tri-plate configuration is used in order to provide efficient coupling to radiator as well as underneath RF circuit. Digital beam forming antenna configuration, detail design of tri-plate fed aperture coupled patch antennas and tri-plate to microstrip aperture coupled transition along with their analyzed and test results are presented.

4 illus, 6 ref

001197   Gupta R;Basu C (Department of Solid State Physics, Indian Association for the Cultivation of Sciences, Jadavpur, Calcutta-700 032) : Magnetic measurement and crystal-field analysis of the optical and magnetic data of Tm₂ (SO₄)₃. 8H₂O crystal. Indian J Phys-Pt A 2001, 75(3), 225-8.

The measurements of the mean magnetic susceptibility and crystalline anisotropy of Tm₂ (SO₄)₃.8H₂O have been carried out in the temperature range 80-300 K. The results of magnetic measurements are explained using a crystal field of C_1h symmetry which is the major symmetry confirmed by optical absorption, Zeeman spectroscopy and para electric resonance experiment. All the results show nearly accidentally degenerate Stark components in the ground state and the presence of the nearl degenerate pair of Stark component within 0.57±0.1 cm^-1 in the ground manifold. A set of crystal field parameters are evaluated using a rigorous approach and making consistent interpretation of both the magnetic and optical data.

2 illus, 1 table, 8 ref