016963   Pohit M;Singh K (Amity School of Engineering, , Sector 125, Noida-201 301) : Survey of applications of simulated annealing and genetic algorithms in filter synthesis and diffractive optics. Asian J Phys 2005, 14(3-4), 353-94.

Simulated annealing (SA) and Genetic Algorithm (GA) are considered as powerful tools for optimization of widely varying classes of problem. For a long time, they have been used in various branches of theoretical as well as applied sciences. Statistically an optimal solution is always possible through these algorithms. There have been numerous applications of these algorithms including the traveling salesman problem, circuit design, data analysis, image processing, neural networks, biological modeling. Like in other fields, optics also has widely varying applications of them in pattern recognition, diffractive optical element design, image reconstruction, phase retrieval, lens design, design of fiber Bragg gratings and so on. Provides a survey of the application of these algorithms in optics with an emphasis on pattern recognition and diffractive optics. A short description is provided on their background and mathematical foundation.

3 illus, 1 table, 325 ref

016962   Ojha K S;Gopal R (Laser and Spectroscopy Lab, Physics Dep, University of Allahabad, Allahabad-211 002) : Laser produced spectrum of B <. Indian J Phys 2006, 80(8), 819-22.

Laser produced spectrum of SiN molecule has been recorded in the region of 360 - 515 nm focusing 532 nm light of pulsed Nd: VAG laser on the rotating and translating SiN rod inside a laser ablation chamber. The spectrum has been recorded and analyzed using Spectra Max and Galactic Grams 32 software. A large number of new bands in addition to the earlier reported bands have been recorded and attributed to B ² Σ⁺ - X ² Σ⁺ and B ² Σ⁺ - A ² Π_i systems of SiN molecule.

5 illus, 2 tables, 13 ref

016961   Majumdar P (Theory Group, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata-700 064, Email: parthasarathi.majumdar@saha.ac.in) : Thermal stability of radiant black holes. Indian J Phys 2006, 80(9), 879-85.

Beginning with, a brief sketch of the derivation of Hawking's theorem of horizon area increase, based on the Raychaudhuri equation, discusses the issue as to whether generic black holes, undergoing Hawking radiation, can ever remain in stable thermal equilibrium with that radiation. Derives a universal criterion for such a stability, which relates the black hole mass and microcanonical entropy, both of which are well-defined within the context of the Isolated Horizon, and in principle calculable within Loop Quantum Gravity. The criterion is argued to hold even when thermal fluctuations of electric charge are considered, within a grand canonical ensemble.

19 ref

016960   Lee S W;Lee J (Quantum Photonic Sci Res Center, Hanyang Univ, Seoul-133 791, korea) : Optimizing quantum teleportation by operational distance. Asian J Phys 2005, 14(3-4), 281-8.

Considers, quantum teleportation via a noisy quantum channel in a Werner state. Teleportation protocol is optimized with respect to closeness measures, fidelity and operational distance. The operational distance provides an operational interpretation as a closeness measure. Optimizes the average operational distance over all possible pure d-dimensional unknown states by altering von Neumann measurement of maximally entangled states and local unitary operation, when the quantum and classical channels are given. It is found that for the quantum channel in a Werner state the optimal protocol is equivalent to the standard teleportation.

1 illus, 18 ref

016959   Lee K S;Schmidt V H (School of Computer-Aided Science, Inje Univ, Gimhae-621 749, Gteongnam, Korea) : High-temperature phase transformation of LiH₂PO₄ and possible solid-state polymerization. Asian J Phys 2005, 14(3-4), 199-205.

The dielectric constant of LiH₂PO₄ powder pellet was measured over the temperature range from 13 to 493 K. A significant change is not observed below room temperature, indicating that the room temperature orthogonal phase is persisted to 13 K. Dielecric constant above room temperature showed two anomalies at 178 °C (T_pl) and at 196 °C (T_p2), which is believed as an onset of dimerization and oligomerization. respectively.

4 illus, 126 ref

016958   Lakhani V K;Sharma P U;Saija K G;Zankat K B; Modi K B (Physics Dep, Saurashtra University, Rajkot-360 005) : Electric and dielectric properties of M_n<. Indian J Phys 2006, 80(8), 789-96.

The compositional and temperature dependent electric and dielectric properties of CO_1+x Mn_xFe_2-2-x O₄ (x = 0.2 - 0.5) spinel ferrite system have been. studied by means of d.c.resistivity, thermoelectric power, a.c.resistivity and dielectric constant measurements. It is found that all the compositions are n-type semiconductor. Low value of mobility and fast rate of decrease of a.c.resistivity as compared to d.c.resistivity, with temperature suggests polaron hopping mechanism. Thermal variation of Seebeck coefficient and charge carrier concentration have been explained on the basis of electron generation at lower temperature and its recombination with holes on increasing temperature. On the other hand, observed abnormal behaviour of dielectric constant with temperature is explained on the basis of contribution of two types of charge carriers.

8 illus, 2 tables, 21 ref

016957   Koo J Y;Kim H;Kim W (NO, Korea Research Institute of Standards and Science, P.O. Box 102, Yuseong, Daejeon-305 600, Korea) : Atomic structure of the C-incorporated c(4 x4) reconstruction on Si(001). Asian J Phys 2005, 14(3-4), 321-8.

The atomic structure of the C-incorporated Si(OO 1 )-c(4X4) surface was studied by using the scanning tunneling microscopy and the ab initio calculations. Founds that there was one C atom in each c(4x4) cell. The incorporated C atoms substitute Si atoms at the fourth-layer α site with the c(4x4) periodicity. The accompanying surface reconstruction is characterized by a dimer vacancy above the C site and two adjacent Si dimers rotated by 90°. The remaining Si dimers are either intact or ejected. This system constitutes a two-dimensionally ordered Si_0.875C_0.125-δ-layer 4 Angstrom below the surface.

6 illus, 26 ref

016956   Koo J H;Cho G (Electrophys Dep, Kwangwoon Univ, 447-1 Wallgye-dong, Nowon-gu, Seoul 139-701, Korea, Email: koo@kw.ac.kr) : Photon tunneling model of ferroelectrics. Asian J Phys 2005, 14(3-4), 309-12.

Proposes a photon correlation theory for ferroelectrics where a photon field has been considered from its constituent electrons. Derives the Curie-Weiss type dielectric susceptibility from the microscopic Hamiltonian. Calculates the free energy by applying the bosonic operators to Hamiltonian. Obtains linear temperature-dependent specific heat C_v in good conformity with experimental data for some ferroelectric materials.

16 ref

016955   Ko J H (Physics Dep, Hallym Univ, 39 Hallymdaehak-gil, Chuncheon-si, Gangwon-do, 200-702, Korea) : Recent research trends in the development of new light sources for the backlight unit of liquid crystal display. Asian J Phys 2005, 14(3-4), 231-7.

Several new light sources are currently under study and development for the applications in the field of the backlight unit (BLU) of liquid crystal display (LCD). Among them, mercury-type and xenon-type flat fluorescent lamps have attracted much interest from the viewpoint of both interesting plasma phenomena and industrial applications. These flat fluorescent lamps exhibit a better light uniformity, by which much thinner designs of backlight unit may be realizable. However; more insights into the discharge phenomena of non-circular cross sections of flat lamps are required for increasing light-generating efficiency. In particular, it is indicated that the aspect ratio of the non-circular cross section might play a very important role in designing efficient discharge space for the flat fluorescent lamp. Recent developmental successes on both mercury-type and xenon-type flat lamps of 32-inch and 40-inch sizes and other light sources such as light-emitting diodes will also be briefly summarized in this short review.

3 illus, 17 ref

016954   Kim S (Phys Dep, Kyonggi Univ, Suwon, Kyonggi-do-442 760) : Fractal analysis of the player's motions in a computer soccer game. Asian J Phys 2005, 14(3-4), 191-7.

Describes a fractal analysis of the player's motions in a computer soccer game. It is important to know the behaviors of the Players during the game. Obtains time series for the x-component (parallel to the touch line) and the y-component (parallel to the goal line) of the player's coordinates by using video analysis techniques. Calculate the values of regularization dimension for the time series. The values of regularization dimension corresponding to tile component parallel to the touchline are slightly less than those of the component parallel to the goal line. Also, the actual dimensional values are rather small. which means that the motions are rather quite straight and smooth. The fractal dimensions of the trajectories of some players are also calculated.

5 illus, 3 tables, 7 ref

016953   Kim K T;Kim M S (NO, Korea Res Inst of Stand and Sci, P.O. Box 102, Yuseong, Daejeon-305 600, Korea) : Brief review on josephson voltage metrology. Asian J Phys 2005, 14(3-4), 207-16.

Discovery of the Josephson effect in early 1960's gave profound impact on the electrical metrology, and the Josephson voltage metrology has been one of the successful examples of practical applications of superconductors. More than 40 Josephron voltage standards are now in operation in the world. Briefly reviews the history of the Josephson voltage standard. Current and future development issues including the programmable Josephson voltage standards (PJVS), the ac Josephson voltage standard (AC JVS) will be described as well. Some theoretical points including. dynamics of Josephson junction and Josephson array, will be introduced which could be heuristic for the students who are willing to endeavour into the physics of the Josephson voltage standards with creative curiosity.

6 illus, 1 table, 73 ref

016952   Kim J S;Lee K H (Phys and Inst of Photonics & Information Technology Dep, Chonbuk National Univ, Jeonju-561 756, S. Korea) : Finite chain with two impurities: analytic solution under general boundary condition. Asian J Phys 2005, 14(3-4), 259-64.

Main steps, taken over three decades for successful completion of the subject using the difference equation method. Are presented in chronological order.

2 illus, 15 ref

016951   Kim J H;Yoneya M;Yokoyama H (Physics, Chungam National University, Daejeon, Korea) : Liquid crystal devices using microscopic orientational patterns. Asian J Phys 2005, 14(3-4), 217-21.

The controlled interaction of the liquid crystals with substrates is a vital factor for the manipulating the liquid crystal property practically. The conventional alignment techniques basically focus on the macroscopically uniform interaction between liquid crystal and its neighboring substrates. A new alignment technique using stylus atomic force microscope (AFM-nano rubbing) has advantages for its accurate and smart controllability. The liquid crystal control using this technique can be realized into the unexplored range of micrometer and nanometer. Shows some outstanding results of this striking alignment technique.

6 illus, 8 ref

016950   Kim D H (School of Physics and Center for Theoretical Physics, Seoul National Univ, Seoul-151, Korea) : On the analytic solutions of the S-K model spin glass in a transverse field. Asian J Phys 2005, 14(3-4), 313-19.

Presents the mathematical details for the analytic solutions of the infinite-range Ising spin glass model with a transverse field to obtain free energy and order parameters under the static approximation. The solutions in both replica symmetric and replica symmetry breaking phases satisfy the asymptotic agreements with the Sherrington-Kirkpatrick replica symmetric solutions and the Parisi replica symmetry breaking solutions, respectively, when the transverse field Γ is set to zero. These boundary conditions were not satisfied by the previous works on the same problem.

8 ref

016949   Kim C S (Physics Dep and Institute for Condensed Matter Theory, Chonnam National univ, Gwangju-500 757, Korea) : Quantum interference in a mesoscopic structure. Asian J Phys 2005, 14(3-4), 251-7.

Studies coherent effects in resonant tunnelling of electrons in the single-barrier semiconductor structures theoretically. The genralized Fabry-Perot scheme is employed to determine the transmission matrix of the system where interface mixing between different envelope bands sets up the multichannel transport problem. Uses the pressure as the tuning parameter to investigate the interplay between the Breit- Wigner and the Fano resonance the transmission. The current-voltage calculation suggests the possibility of observing the predicted effects of manipulating resonances artificially

3 illus, 15 ref

016948   Kim B G;Jang H M (Physics Dep, Pusan National Univ, San 30 Jangieon-dong, Pusan-609-735, Korea) : Dipolar relaxation in La modified A-site vacancy PbTiO₃. Asian J Phys 2005, 14(3-4), 275-80.

Measures the frequency-dependent complex dielectric constant as a function of temperature on La-modified A-site vacancy PbTiO₃. As La concentration increases, T_max at which dielectric constant has maximum values decreases. T_max at each sample coincides with the cubic-tetragonal structural phase transition temperature from x-ray scattering experiments. At low temperature, dielectric relaxation phenomena have been observed. By comparing dielectric constant above and below relaxation frequency, the high dielectric constant in this system is originated not from space charge effect but from dielectric relaxation. The temperature dependence of dielectric relaxation follows Arrhenius law, whichmeans thermally activated mechanism.

4 illus, 1 table, 17 ref

016947   Khandpekar M M (Physics Dep, Birla College, Kalyan-421 304) : Dielectric properties of mixed glycine fluoride crystals. Indian J Phys 2006, 80(8), 841-3.

Glycine Hydrogen Potassium Fluoride (GHKF) crystals were grown from aqueous solution by slow evaporation method for the first time. The variation of conductivity with temperature (30°C - 120°C) was measured. The variation in dielectric constant (K) and tangent loss of pressed specimens as a function of frequency in range 400Hz - 1 MHz was recorded. The change in dielectric constant with temperature and applied d.c bias was made. The conductivity is found to be very low and decreases drastically with rise in temperature. The dieU:ctric constant is found to be independent of the applied d.c bias. Dielectric constant (K) and tan δ decreases with frequency to attain fixed value at high frequencies. a typical of a dielectric solid with dipole and migrational polaris at ions. The dielectric constant versus temperature curve exhibits diffused ferroelectric phase transition.

5 illus, 15 ref

016946   Karan S;Sen Gupta S P (Materials Sci Dep, Indian Association for the Cultivation of Science, Jadavpur, Kolkata-700 032) : Microhardness studies on urea-doped solution grown single crystals of epsomite. Indian J Phys 2006, 80(8), 781-7.

The presence of impurities, even in a minute amount in the parent phase, has considerable effect on the growth morphology, chemical nature and mechanical properties of the grown crystals. Highly transparent crystals having well-defined morphology can be grown by doping at a very low concentration. A Vickers microhardness study has been done on solution grown single crystals of urea-doped epsomite (MgSO₄, 7H₂O) over a load range of I0-80g. The Vickers hardness numbers (H₁) are found to decrease with increase in load and then appear to level off. It is found that hardriess of the crystals increases with the amount of doping. Meyer's index `n' is found to be less than 2 for both the pure and doped cases and thus, the whole system belongs to the soft material category. Neither Kick's law nor Hays and Kendall's law can fully explain the nonlinear variation of microhardness with load. Instead, preference is' given to Li and Bradt's proportional specimen resistance (PSR) model. The elastic stiffness coefficient CII has also been estimated using Wooster's empirical relation from the hardness data.

4 illus, 35 ref

016945   Kar S (Dep of Physics and Centre for Theoretical Studies, Indian Institute of Technology, Kharagpur-721 302) : Focusing of branes in warped backgrounds. Indian J Phys 2006, 80(9), 873-7.

Branes are embedded surfaces in a given background (bulk) spacetime. Assuming a warped bulk, investigates in analogy with the case for geodesics, the notion of focusing of families of such embedded, extremal 3-branes in a five dimensional background. The essential tool behind the analysis, is the well-known generalised Raychaudhuri equations for surface congruences. In particular, finds explicit solutions of these equations. which seem to show that families of 3-branes can focus along lower dimensional submanifolds depending on where the initial expansions are specified. Concludes with comments on the results obtained and possibilities about future work along similar lines.

7 ref

016944   Kale R K (NO, Defence Institute of Advanced Technology, Pune-411 025) : Low-current scanning tunneling microscope for nanoscale imaging. Def Sci J 2006, 56(4), 599-613.

Advances in the nanotechnology, which is still in its infancy, will depend on ability to design, build, replicate, and mass-produce usable nanoscale systems. At sub-nanometer length scales, scanning tunneling microscopy (STM) and the related techniques, collectively called scanning probe microscopies, replace the optical microscopy for real-space imaging and manipulation of materials. STM operationis based on measurement of current due to tunneling of electrons across a finite potential barrier between the probe and the sample. In conventional STM, tunneling current of tens of nA and probe-sample distance of a few Angstrom are maintained. These conditions while necessary for atomic-scal imaging under ultra high vacuum environment, are not suited to handle nanostructures. Quantum structures depossited on a flat substrate usually present a non-metallic sample, and the roughness levels involved are much too high for conventional STM. STM operation withlow tunneling current (few pA) and larger tunneling gap (several nm) is preferred to overcome these difficulties. Experimental work and theoretical considerations for developing an atmospheric low-current STM (LC-STM) has been presented. Researchers from diverse fields can build their own LC-STM for routine imaging and spectroscopy. Several design details are included keeping this aspect in mind.

9 illus, 12 ref

016943   Huang J Y (Pohang Accelerator Laboratory, , Pohang-790-784, Korea) : Femto-second electron and photon beam diagnostics for SASE XFEL. Asian J Phys 2005, 14(3-4), 329-37.

Beam diagnostics for self amplification of spontaneous emission (SASE) x-ray free electron laser (XFEL) calls for precision of femto-second in time structure and sub-micrometer in beam position measurement. Existing instruments can be used for standard diagnostics such as single bunch charge measurement. wire scanner or optical transition radiator for beam size measurement. In a SASE XFEL, instead, major development efforts should be performed on the measurement offemto-second bunch structure and sub-micrometer transverse beam position measurement techniques. Femto-second bunch length measurement can be possible using electro-optic crystal, coherent transition radiation, and transverse deflecting cavity. Nanometer beam position measurement technique being developed in collaboration with linear collider group can also be utilized for sub-micrometer beam position measurement in an XFEL. Overall plan and the ongoing development activities toward X-ray FEL will be presented.

6 illus, 3 tables, 22 ref

016942   Hong H K;Park J W;Lee K S;Yoon C S (Physics Dep, KAIST, Daeduck Science Town, Daejon-305 701, ) : Application of molecular recognition concept to the growth of highly nonlinear organic crystal, 3-methyl-4-methoxy-4'-nitrostilbene (MMONS). Asian J Phys 2005, 14(3-4), 239-46.

Despite their excellent nonlinear optical, electrooptic, piezoelectric, pyroelectric, photorefractive, triboluminescence properties, the growth of polar organic crystals of large size and high quality, being essential for exploring and utilizing such properties, has rarely been succeeded. Reports on the growth of 3-methyl-4-methoxy-4' -nitrostilbene (MMONS) crystal, which are highly polar and show one 0 the largest second-order non-linear optical susceptibilities. The overall morphology of MMONS crystals is governed by unidirectional growth along a direction of the polar axis. They grew only in the +c direction of the polar axis and growth virtually ceased in the -c direction. The observed polar morphology and growth behavior may be explained by the molecular recognition concept. Utilizing the unidirectional growth, single crystals of a large size (40 x 40 x 40 mm³) and of high perfection were grown by the low temperature solution growth method using methyl ethyl ketone as a solvent.

6 illus, 1 table, 30 ref

016941   Hareesh Kumar P V;Sanilkumar K V;Panchalai V N (Naval Physical and Oceanographic Laboratory, , Kochi-682 021) : Shallow water internal waves and associated acoustic intensity fluctuations. Def Sci J 2006, 56(4), 485-493.

Physical oceanographic and acoustic data were simultaneously collected from the coastal waters of the Arabian Sea. Acoustic transmissions were carried out from an anchored vessel using 620 Hz transducer and received by an array of hydrophones moored at <126> 5 km away from the anchorage. Thermal structure in this region was characterised by a tri-layer structure, ie, a strong thermocline (<62> 0.4°C/m) sandwiched between an upper (<60> 10 m) and bottom (<62> 25 m) homogeneous layer. High-resolution (sampled at 10 s interval) temperature data from moored sensors revealed intense internal wave activity. The maximum value of Brunt-Vaisala frequency, which is the maximum frequency limit of internal waves in the thermocline, suggests that the upper frequency limit of the internal wave, which can be generated during this period, is 23 cph (2.6 min). High and low frequency waves caused variations of <126>3°C and <126>5°C respectively in the temperature field. But the low frequency internal waves were found to contain maximum energy compared to the high frequency waves. Fluctuations of 8-12 dB were noticed in the measured acoustic intensity values in the presence of low frequency internal waves. Simulation studies carried out using parabolic equation model using 620 Hz source indicated well-defined ducted propagation with minimum transmission loss, when the source was kept within the homogeneous layer. The presence of tri-layer thermal structure, ie, a strong gradient layer sandwiched between an upper and bottom homogeneous layer, caused surface and bottom channel propagation in this region.

7 illus, 16 ref

016940   Ghosh D;Deb A;Haldar P K;Guptaroy S (Nuclear and Particle Physics Research Centre, Physics Dep, Jadavpur University, Kolkata-700 032) : Azimuthal pion fluctuation and phase transition in ultra-relativistic ring-like and jet-like events. Indian J Phys 2006, 80(8), 807-13.

Presents an analysis of ring-like events and jet-like events in ¹⁶O-AgBr interactions at 60 A GeV in terms of Scaled Factorial Moments (SFMs) in azimuthal space upto the sixth order of moments. The analysis reveals that non-thermal phase transition is clearly signalled by the data in case of jet-like events. No such phase transition is observed in ring-like events.

6 illus, 3 tables, 25 ref

016939   Ghosh A;Mitra P (Theory Div, Saha Institute of Physics, 1/AF Bidhannagar, Kolkata-700 064) : Counting of black microstates. Indian J Phys 2006, 80(9), 867-71.

The entropy of a black hole can be obtained by counting states in loop quantum gravity. The dominant term depends on the Immirzi parameter involved in the quantization and is proportional to the area of the horizon, while there is a logarithmic correction with coefficient -1/2.

7 ref

016938   Devlal K;Kholiya K (Physics Dep, G.B. Pant University of Agriculture and Technology, Pantnagar-263 145, Email: k_devlal@rediffmail.com) : Analysis of equations of state for metals and rare gas solids. Indian J Phys 2006, 80(8), 801-5.

A comparative study of different equations of state is presented for some metals and rare gas solids. It is shown that the Poirier ªTarantola, Suzuki and Shanker equations of state are new approaches but they do not improve the results for compression behavior, although these equations required a lot of computation work. The results obtained by Poirier-Tarantola show a significant improvement as compared with Suzuki, and Shanker formulations. The results obtained by Hama-Suito EOS are very high. The Tait EOS is found to give far better agreement with the available experimental results than these new equations. The Tait's EOS is further extended to study the thermal expansion behavior of solids by inclusion of the concept of thermal pressure. The new modified Tait's isobaric EOS gives good agreement between calculated and experimental data which demonstrate the validity of the modified EOS.

7 illus, 2 tables, 25 ref

016937   Dave M S;Patel K R;Vaidya R D;Patel S G (Physics Dep, Sardar Patel University, Vallabh Vidyanagar-388 120, Email: shantibhaip@yahoo.com) : Growth and characterization of NbS_x Se_2-x single crystals. Indian J Phys 2006, 80(8), 797-800.

The series of niobium sulphoselenide (NbS_xSe_2-x where 0 ≤ x ≤ 2) single crystals have been grown by chemical vapour transport technique using iodine as a transporting agent. The optimum conditions for the growth of these crystals are reported. The stoichiometry of the grown crystals was confirmed on the basis of energy dispersive analysis by X-ray (EDAX). The thermoelectric power (TEP) has been measured for the as grown crystals in the temperature range of 303K- 403K. The Seebeck coefficient `S', Fermi energy 'E'_f and effective mass of electron have. been calculated. The p-type nature of the as grown crystals was inferred from both TEP measurements as well as Hall effect measurements. The electrical resistivity perpeadicular to c-axis (i.e. along to the basal plane) and parallel to c-axis (ie. normal to the basal plane) have been carried out in the temperature range of 303 K - 403 K, which gives the confirmation about the semiconducting behaviour. The data obtained for resistivity have been discussed in accordance with the proportion of sulphur in the present series.

4 illus, 4 tables, 24 ref

016936   Das T K (NO, Theoretical Institute for Advanced Research in Astrophysics, 101, Section 2, Kuang Fu Road, Hsinchu, Taiwan) : Astrophysical accretion as an analogue gravity phenomena. Indian J Phys 2006, 80(9), 887-934.

Reports that in genral, the transonic accretion in astrophysics can be considered as an example of the clasical analogue gravity model.

221 ref

016935   Choudhury D K;Gogoi R (Physics Dep, Gauhati University, Guwahati-781 014) : Self-similarity and a parameterization of proton structure at small x. Indian J Phys 2006, 80(8), 823-7.

Sometimes back the concept of self-similarity in the structure of the proton at small x has been introduced. Authors make reanalysis of recent HERA data modifying the formalism proposed by Lastovicka so that the measured fractal dimensions of proton are all positive. Further improvement of the model is also suggested.

4 illus, 1 table, 26 ref

016934   Cho S Y;Cho D H;Ryu M K;Kim J S;Jang M S;Kim J P (Phys Dep and Res Cent for Dielect and Advanced Matter Physics, Pusan National, Busan-609-735, Korea) : Dielectric and ferroelctric properties of (1-X) PBFe_0.5 Ta_0.5O_3-xPbTiO₃ ferroelectric ceramics. Asian J Phys 2005, 14(3-4), 295-300.

Lead-based complex compounds. (l-x)PbFe_0.5Ta_0.5O_3-xPbTiO₃3 ceramics. were prepared by a solid-state reaction method. and corresponding dielectric and ferroelectric properties were investigated in a wide range from x = 0 to x = I. The crystal structure changed from a cubic to a tetragonal system above x = 0.2. The phase transition temperature of (1-x)PbFe_0.5 Ta_0.5O₃-xPbTiO₃ ceramics shifts toward a high temperature with increasing PbTiO₃ concentration. The phase transition shows ferroelectric relaxor behavior with a broad dielectric constant maximum. Ferroelectric P-E hysteresis loops with a high remanent polarization were obtained at x = 0.3 <126> 0.4.

8 illus, 1 table, 12 ref

016933   Banerjee V (Physics Dep, Indian Institute of Technology, New Delhi-110 016) : Dielectric relaxation in ferroelectric glasses. Asian J Phys 2005, 14(3-4), 265-73.

Studies the dielectric relaxation in a hydrogen bonded mixed ferro- and antiferro-eletric crystal based on the mean field and analysis of the random bond, random field Ising model in a transverse field. Compares results with existing experimental measurements on Rb_l-x(NH₄)_xH₂PO₄ which is amongst the most well studied prot lasses and its classical counterpart Rb_l-x(ND₄)_xD₂PO₄ referred to as deuteron glass.

1 illus, 25 ref

016932   Ajit Kumar;Sarma A K (Phys Dep, Indian institute of Technology, New Delhi-110 016) : Soliton switching in a three-core coupler with nonlinear saturation. Asian J Phys 2005, 14(3-4), 339-46.

Carries out a numerical study of soliton switching in a three-core coupler with saturating nonlinearity. In this context, considers both,the commonly used unaveraged model with fractional form of nonlinear saturation and its averaged counterpart. Shows, in the case of saturating nonlinearity, soliton switching is possible only in the weak coupling regime. Inspite of the fact that switching is confined only to the weak coupling regime, a threecore coupler with saturating nonlinearity is preferable to its Kerr counter part in terms of the critical power for switching as well as the complete and stable regime of switching.

3 illus, 2 tables, 24 ref

016931   Ahn S J;Kim J H;Choo W K (Phys Dep, KAIST, Daejeon-305 701) : Temperature dependent random field in relaxor ferroelectrics. Asian J Phys 2005, 14(3-4), 289-93.

Temperature dependence of random field is found to be intrinsic in a relaxor ferroelectric (RF) Pb(Yb_1/2Nb_l/2)O₃- PbTiO₃ [PYN-PT] by Raman Optical Activity measurements. Its implications towards the formation of polar nano regions (PNR) in the relaxor ferroelectrics are explored. Both inter-PNRs relaxation and intra-PNR relaxation contributing to the very broad and complicated spectrum of relaxation are temperature dependent, which are analyzed by Vogel Fulcher law and phonon-assisted tunneling model respectively.

3 illus, 2 ref

015981   Wankhede D S;Wankhede N N;Lande M K;Arbad B R (Chemistry Dep, Dr Babasaheb Ambedkar Marathwada University, Aurangabad-431 004, Email: abr_chem@yahoo.co.in) : Ultrasonic velocities and refractive indices of binary mixtures of propylene carbonate + n-alkanols. Indian J pure appl Phys 2006, 44(12), 909-16.

The densities, ultrasonic velocities and refractive indices of binary mixtures of propylene carbonate + ethanol, n-propanol and n-butanol at 298.15, 303.15 and 308.15 K have been measured over the whole mole fraction range. Experimental data have been used to estimate the isentropic compressibility (K_s), intermolecular free length (L_f), specific acoustic impedance (Z), polarizability (α) and their deviations excess isentropic compressibility (K_s^E), excess intermolecular free length (L_f^E), excess acoustic impedance (Z^E) and excess refractive index (Δn_D). The results have been fitted to Redlich-Kister equation and discussed in terms of molecular interactions.

4 illus, 4 tables, 18 ref

015980   Varshney N K;Ram Prakash (Mathematics Dep, S.V. College, Aligarh, Uttar Pradesh) : Effect of heat source on MHD convective flow of viscous fluid through a porous medium bounded by an oscillating porous plate in slip flow regime. Indian J Theor Phys 2006, 54(1), 59-67.

An analysis of velocity, temperature, skin-friction and rate of heat transfer of the flow of a viscous incompressible fluid of small electrical conductivity is made in a porous medium near an oscillating inginite porous flat plate in slip flow regime under influence of a transverse magnetic field of uniform strength. The velocity of fluid increase with increase in K (porosity parameter), but it decrease with increase in M (Hartmann number) and temprature of fluid decrease with the increase in Pr (Prandtl number) and Q (source parameter).

2 illus, 2 tables, 15 ref

015979   Tiwari B V;Mishra R;Varma P;Tiwari M S (Dep of Physics & Electronics, Dr H S Gour University, Sagar-470 003) : Generation of kinetic alfven wave by velocity shear in the plasma sheet boundary layer during substorm. Indian J pure appl Phys 2006, 44(12), 917-26.

The kinetic Alfven wave (KAW) driven by velocity shear in the plasma sheet boundary layer (PSBL) has been investigated. Expressions for the dispersion relation and growth rate of the kinetic Alfven wave have been derived for the two regimes separately i.e., for the case of weak shear and strong shear. It is found that for both weak and strong shear regimes the resonant electrons act as the main energy source whereas; the ion longitudinal motion suppresses the instability in case of the strong shear. The results explain the generation of energetic KAWs in the PSBL during the substorm onset by the weak velocity shear. As the shear becomes strong during the substorm the energy of the KAWs is transferred to the plasma particles through the Landau damping of the wave, which may then lead to the parallel energisation of the electrons observed recently by Polar satellite. The loss of the Poynting flux, as observed by Polar and Akebono satellite, is also explained in terms of the Landau damping of the KAW by the strong shear of substorm. The temperature anisotropy and density of the plasma particles enhance the growth rate of shear driven KAW at the onset of the substorm.

12 illus, 25 ref

015978   Tewari S P;Sood J (Physics & Astrophysics Dep, University of Delhi, Delhi-110 007, Email: sptewari@physics.du.ac.in ) : Reflectivity of low energy photons from one and two dimensional rare hot quantum and classical plasmas. Indian J pure appl Phys 2006, 44(12), 927-9.

The reflectivity of low energy photons from wave vector dependent plasma modes present in one- and two-dimensional rare hot quantum and classical one component plasmas has been computed. The computations have been made for different densities - linear in ID and areal in 2D at various temperatures to bring out the difference between quantum and classical plasmas. It turns out that the effect of Landau damping is quite significant amongst other results.

3 illus, 8 ref

015977   Sudhakar Reddy B;Buddhudu S (Physics Dep, Sri Venkateswara University, Tirupati-517 502, Email: sudhakar_b9@rediffmail.com) : Spectral analysis of Cu<. Indian J pure appl Phys 2006, 44(12), 887-95.

The development and optical spectral analysis of Cu²⁺ (0.5 mol %) doped three new glasses have been reported in the following composition: 10TeO₂-69.5 B₂O₃-10 Li₂O-10 AlF₃; 10CdO-69.5 B_{2O3-10 Li2O-10 AlF3; 10ZnO-69.5 B2O3-10 Li2O-10 AlF3. Due to the homogeneous distribution of Cu²⁺ ions, both CdO and ZnO containing glasses are found to be in bright blue colour, but a greenish blue colour has been noticed from the TeO2 containing glass, the reason for this has been explained. Without the Cu²⁺ ions, the reference glasses have also been prepared and found them in good transparency with excellent resistance towards the moisture without any degradation on their surfaces. Based on the XRD profiles, amorphous nature of these glasses has been confirmed. Due to the presence of TeO2, the UV transmission for the glass is found to be extended up to 300 nm compared with the other two glasses. Under an UV source (254 nm), a blue emission has been noticed from the surfaces of the glasses. From the measured absorption spectra of these copper glasses, a abroad absorption band at 800 nm and a weak absorption band (²B1g → ²B2g) at 387 nm have been measured to examine the effects of the CdO, ZnO and TeO2 contents in the glasses studied. FTIR spectra of these glasses have also been analyzed to investigate the glass structures. Emission spectra of (0.5 mol %) Cu²⁺: B2O3-(TeO2/CdO/ZnO)-Li2O-AlF3 have revealed two emissions at 415 and 438 nm with an excitation at 371nm.}

12 illus, 2 tables, 36 ref

015976   Srivastava R C (Mathematics Dep, D.D.U. Gorakhpur University, Gorakhpur) : Shock wave in sonoluminescing gas bubble. Indian J Theor Phys 2006, 54(1), 15-29.

The collapsing gas bubble under ultrasound field generates the phenomena of sonoluminescence. The covergence of shock wave produces very high temperature which ionizes the gas inside the bubble causing the emission of light. The physical variables near the centre of convergence is studied. The numerical model is based on conservative form of two dimensional time dependent system of Eulerian equation with an equation of state for ideal gas. The symmetry preserving character of the invariant difference scheme under use was proved numerically by calculation over a long interval of time. The sufficiently high temperature obtained predicts the ionization of the gas inside the bubble and oocurance of sonoluminescence phenomena.

015975   Sinha K P;Meulenberg A (Physics Dep, Indian Institute of Sciences, Bangalore-560 012, Email: mules33@excite.com) : Laser stimulation of low-energy nuclear reactions in deuterated palladium. Curr Sci 2006, 91(7), 907-12.

Models to account for the observed experimental results for low-energy nuclear reactions in palladium-deuteride systems are presented along with calculated results. The crucial idea is a mechanism of improved probability for the needed penetration of the Coulomb barrier for a D-D reaction. This facilitation occurs, in general, with the formation of D^- ions at special frequency modes (e.g. via phonons) and, specifically for the laser-stimulated case, with utilization of enhanced optical potential at a selected interface. Both mechanisms may work individually, or together, to increase the probability of barrier penetration.

3 illus, 12 ref

015974   Shah K A;Islam S S (Dep of Applied Sciences and Humanities, Faculty of Engineering and Tec, Jamia Millia Islamia (Central University), New Delhi-110 025, Email: Shahkhurshaid@yahoo.co.in) : Temperature, current and doping dependence of non-ideality factor for pnp and npn punch-through structures. Indian J pure appl Phys 2006, 44(12), 953-8.

The effect of punch-through in devices is of great importance in electronic industry. An efficient, unconditionally stable, simple and accurate method has been presented for solving non-linear transport equations for carriers with appropriate choice of initial values of dependent variables. The methods are so fast that parameter dependence of non-ideality for punch-through structures has been incorporated easily and their specific effects have been determined precisely. Reveals that the non-ideality factor decreases with temperature and increases with current and doping concentration of the active region of the device. The relative changes are larger at lower temperatures and more effective at higher impurity density of the active region of the device. This study enables to have better understanding of the punch-through mechanism and design of these devices.

2 illus, 20 ref

015973   Sengwa R J;Madhvi;Abhilasha;Sankhla S (Physics Dep, Dielectric Research Laboratory, J N V University, Jodhpur-342 005) : Study of dielectric relaxation and dipole moment of some hydrogen bonded solvent binary mixtures in 1,4-dioxane. Indian J pure appl Phys 2006, 44(12), 943-52.

The dielectric relaxation and dipole moment of different concentration binary mixtures of mono methyl, mono ethyl and mono butyl ethers of ethylene glycol with four polar solvents i.e. ethyl alcohol, glycerol, dimethyl sulphoxide and dimethyl formamide have been measured in dilute solutions of 1,4-dioxane at 35°C. The measured values of permittivity (ε) and dielectric loss (ε") at 10.1 GHz, static dielectric constant (ε₀)at 1 MHz and high frequency limiting dielectric constant (ε_∞) have been used to determine the values of molecular relaxation time (τ₀), and dipole moment (μ) of the different composition binary mixtures. The analysis of the results based on hetero-association in these binary systems, indicates the existence of different characteristic heterogeneous species in dilute solutions. The comparative values of τ₀ and μ of the various binary mixtures of different composition also suggest that the nature of heterogeneous interaction varies with the type of polar solvent and also constituents composition in the binary mixture.

4 illus, 2 tables, 41 ref

015972   Sandeep Kumar;Sharma D R;Thakur N;Negi N S; Rangra V S (Physics Dep, Himachal Pradesh University, Shimla-171 005, Email: sndp_bhardwaj@yahoo.com) : Molecular associations in binary mixture of pyridine and N, N-dimethylacetamide in benzene solution using microwave absorption data. Indian J pure appl Phys 2006, 44(12), 939-42.

The dielectric relaxation time (τ) of binary mixtures of different molar concentrations of pyridine (C₅H₅N) and N, N-dimethylacetamide (DMA) in benzene solution has been calculated by using standard microwave techniques and Gopala Krishna's [Trans Farad Soc, 33 (1957) 767.] single frequency (9.875 GHz) concentration variational method at different temperatures (25, 30, 35 and 40°C). It is found that the dielectric relaxation time (τ) varies non-linearly with the increasing molar concentration of pyridine in the binary mixture of pyridine and DMA. Hence, solute-solvent and solute-solute molecular associations have been proposed.

4 illus, 1 table, 14 ref

015971   Raychaudhuri A;Karanjai S (Mathematics Dep, Sikkim Manipal Institute of Technology, Sikkim-737 132) : Radiative transfer problem in semi infinite atmosphere with henyey greenstein phase function using a modified form of spherical harmonic method. Indian J Theor Phys 2006, 54(1), 81-8.

A new modification of the form of the intensity in the double interval spherical harmonic method has been introduced to solve the integro-differential equation of radiative transfer. The method was used to solve problems in case of plane geometry planetary and Rayleigh phase function. Here it is extended to the problem in semi-infinite atmosphere with Henyey-Greenstein phase function and the form of the intensity, φ(τ) has been taken to be φ(τ) = Ae^φ +Be^-τ, -where A and B are constants and τ is small.

015970   Ojha S (NO, Asharia Iswaripur High School, Barunda, Howrah, West Bengal) : Eigen value approach to thermal stresses in an anisotropic elastic slab due to prescribed surface temperature in certain special cases. Indian J Theor Phys 2006, 54(1), 69-79.

In vector matrix solution of the problems of thermal -stresses in an anisotropic material, generally the eigen values occuring in the matrix equation are taken as unequal. Author has have studied the title problem when the eigen values are equal.

10 ref

015969   Mehta N;Kumar D;Kumar A (Physics Dep, Pranveer Singh Institute of Technology, Kanpur) : Compensation effect of AC conduction in Se₈₀Te₂₀ and Se₈₀Te₁₀M10 (M = Cd, In, Sb) chalcogenide glasses. Indian J pure appl Phys 2006, 44(12), 935-8.

In many amorphous and liquid semiconductors and other class of materials, Meyer-Neldel rule is observed in the dc conductivity, where the pre-exponential factor (σ₀) is found to increase exponentially with the activation energy (ΔE). The observation of Meyer- Neldel rule in case of ac conductivity near the room temperature in bulk samples of Se₈₀Te₂₀ and Se₈₀Te₁₀M₁₀ (M = Cd, In, Sb) chalcogenide glasses has been reported.

3 illus, 5 tables, 20 ref

015968   Kumar P;Prasad S C;Mishra L K (Physics Dep, T.S. College, Hisua, Nawada, Bihar-805 103) : Evaluation of the zero temperature phase coherence length for a superconducting fermionic system. Indian J Theor Phys 2006, 54(1), 1-14.

Using the theoretical formalism of Pistolesi and Strinati [Phys. Rev., 1353, 15168 (1996)] author have numerically evaluated the phase coherence length εphase at various values of loop expansion parameter λ. Our theoretical result indicates that there is possibility of crossover from BCS (weak coupling limit) to BE (strong coupling limit).

4 tables, 23 ref

015967   Kaura S K;Virdi S P S;Aggarwal A K (Coherent Optics Div, Central Scientific Instruments Organisation, Chandigarh-160 030, Email: skkaura_22@rediffmail.com) : Holographic optical elements encoded security holograms with enhanced features. Indian J pure appl Phys 2006, 44(12), 896-902.

A simple and cost-effective two-step method for forming encoded security holograms with enhanced features is described in this paper. These security holograms contain enhanced encoded/concealed anti-counterfeit security features, which can only be decoded using a key hologram in the final reading process. The encoded key hologram and the security hologram are in the form of special encoded complex holographic optical elements. When the security hologram is illuminated with the decoding beam, specific moire-like fringe patterns are formed on the security hologram and in addition several spatially separated bright focused spots are also generated from the security hologram. A careful spatial filtering of these bright spots results in specific moire patterns at different locations in the observation plane and moreover these patterns contain variable interferometric features. Further, these moire patterns disappear when the security hologram is perfectly repositioned and only the variable interferometric features are formed. Since these security holograms contain variable interferometric features in addition to the specific moire patterns and bright focused spots, thus making these holograms suitable for both visual and as well as machine inspection.

7 illus, 15 ref

015966   Kannappan V;Askar Ali S J;Abdul Mahaboob P A, (Postgraduate and Research Dep of Chemistry, Presidency College (Autonomous), Chennai-600 005) : Determination of stability constants of charge transfer complexes of iodine monochloride and certain ethers in solution at 303 k by ultrasonic method. Indian J pure appl Phys 2006, 44(12), 903-8.

Ultrasonic velocities (U), densities (ρ), and coefficient of viscosities (η) are measured for solutions containing iodine monochloride (ICI) and one of the following ethers in equimolar concentration in the range 0.001-0.01M at 303 K. The diphenyl ether, 4-chloroanisole, anisole and 1,4-dioxane are used as donors and the dichloromethane, chloroform, carbon tetrachloride and n-hexane have been used as solvents. Acoustical parameters such as adiabatic compressibility (β), absorption coefficient (<97>2), internal pressure (π) and cohesive energy (CE) values are calculated from the measured values of U, ρ and η. The trend in the acoustical parameters establishes the formation of charge transfer complexes between iodine monochloride (acceptor) and ethers (donors). The stability constants (K) are calculated for these complexes. The free energy changes (ΔG) for the formation of these complexes are also calculated from K values. The formation constants with polarizability, dielectric strength and dipole moment of the donor and solvent molecules have been correlated. The free energy of activation (ΔG^#) and viscous relaxation time (τ) are found to be almost constant for these complexes indicating the formation of similar charge transfer complexes in these systems.

9 illus, 4 tables, 14 ref

015965   Goswami A (NO, Batiswar Dr. Sailendra Dhananjoy Vidyapeeth, 24-Parganas, West Bengal) : Problem of thermoelasticity in a non-simple medium due to impulsive stress at the boundary. Indian J Theor Phys 2006, 54(1), 31-41.

Deals with the solution of a one-dimensional dynamical coupled problem of thermoelasticity in a semi-infinite non-simple medium when its bounding surface is subjected to an impulsive stress.

2 illus, 2 tables, 6 ref