019132   Babynanda Devi O (Physics Dep, Manipur Univ, Canchipur, Imphal-795 003, Email: o_babynanda@rediffmail.com) : Algebraic properties of energy raising and lowering ladder operators for the finite and infinite spectrum potential systems. Indian J Phys 2012, 86(11), 1003-11.

An enquiry is made into the Lie algebraic property of the energy raising and lowering ladder operators for a discrete (bound state) spectrum. Starting with the most general construction of these operators in the energy representation author investigate the necessary and sufficient conditions for these operators to form a realization of su(1,1) or su(2) algebra. Formally establish the truth of the undeclared conjecture that a finite spectrum bound state system carries a realization of su(2) algebra and that an infinite spectrum bound state system carries a realization of the su(l,l) algebra. Discussed the position space realization of these operators for some well known solvable potential systems.

20 ref

019131   Al-Khaykanee M K;Ibrahim Aboud H (Physics Dep, College of Science, Babylon Univ, Iraq, Email: Mohsin_7704@yahoo.com ) : Electronic properties for di-amino naphthalene: B3LYP density functional theory calculations. Int J pure appl Sci Technol 2013, 15(1), 1-13.

Theoretical studies for calculating molecular structure parameters of naphthalene and its simplest derivatives with electron-donating groups (di-amino) in different positions were performed using DFT. Based on B3LYP with 6-31 (d, p) basis set was used to investigate the effect on the electronic and structure properties for the positional variation of the amino subgroup in the naphthalene. The optimized structures, total energies, electronic states, energy gaps, ionization potentials, electron affinities, chemical potential, global hardness, softness, global electrophilictity, dipole moment and dipole polarizability were calculated. The harmonic vibration frequencies calculated and compared with available experimental data. The results showed a decrease in gap energies and the presence of the electron-donating groups leads to easy oxidation.

8 illus, 4 tables, 28 ref

019130   Ahmed M (Physics Dep, Faculty of Science, King Abdulaziz Univ, M.B. 20803, Jeddah 21589, Saudi Arabia, Email: mostafa.hafez@science.miniauniv.edu.eg) : Modeling and simulation of dispersion-limited fiber communication systems employing directly modulated laser diodes. Indian J Phys 2012, 86(11), 1013-20.

This paper quantifies the role played by fiber dispersion in limiting the transmission distance in directly modulated gigabit optical fiber communication systems (OFCSs). The study is based on modeling and simulation of an OFCS deploying a directly modulated 1.55-um distributed feedback InGaAsP laser diode, a single-mode fiber and a PIN photodetector. The repeater distance of the system is decided to correspond to a bit error rate of 10^-9. The receiver sensitivity corresponding to the back-to-back configuration is calculated. Fiber attenuation was found to limit the maximum transmission distance to 162-202 km under bit rates ranging between 1 and 10 Gbps. This distance was found to be less affected by counting the chromatic dispersion of the fiber up to bit rate of 2 Gbps. A dramatic decrease in the transmission distance is predicted when the bit rate increases further and the system becomes dispersion limited. Influence of dispersion on the transmission distance is quantified in terms of the power penalty of the OFCS system associated with taking account of fiber dispersion. This power penalty is predicted to be within 7 dB for bit rates below 5 Gbps but jumps to values as high as 22 dB at higher bit rates.

7 illus, 1 table, 22 ref

018067   Yehya F;Chaudhary A K (NO, Advanced Centre of Research in High Energy Materials Hyderabad Univ, Hyderabad-500 046, Email: anilphys@yahoo.com) : Low-limit detection of NO₂ by longitudinal mode selection in a photoacoustic resonant system. Pramana J Phys 2013, 81(3), 535-45.

The paper reports the pulsed laser-based photoacoustic (PA) spectroscopy of NO2 in a resonant PA cavity with special filters made of stainless steel. The PA cell along with special types of sound filters are designed and fabricated to excite only the second-order longitudinal mode inside the cavity. The second harmonic, i.e. λ = 532 nm pulse width, of 7 ns obtained from Q-switched Nd:YAG laser at 10 Hz repetition rate has been used to study the saturation behaviour of the PA signal and absorption coefficient with respect to the input laser energy. Generally, the Q-factor of longitudinal modes in the acoustic cavities is quite low. However, by modifying the design of the cell and the filter, we can achieve high value of Q = 30. The combination of special filter along with the experimental data acquisition technique helped us to achieve the minimum detection concentration of NO₂ of the order of 9 ppbV which is much better than the previous value of the same PA cell without filter [Yehya and Chaudhary, Appl. Phys. B 106, 953 (2012)].

8 illus, 1 table, 22 ref

018066   Wagh S M (NO, Central India Research Institute, 34, Farmland, Ramdaspeth, Nagpur-440 010, Email: waghsm.ngp@gmail.com) : Acceleration dependence of doppler effect in light. Pramana J Phys 2013, 81(3), 439-48.

Using only the geometric relationships of suitable locations, authors analyse Doppler effect in light to show how the acceleration of the source also contributes to the Doppler shift. Authors further propose that an experiment be performed using cyclotron-type devices to determine the acceleration dependence of the Doppler shift.

6 illus, 22 ref

018065   Tasa B P;Das Pompy;SInha A;Chenglari T; Bordoloi H (DBCET, , Azara, Guwahati, Email: bish94002@gmail.com) : Simulation based R-peak and QRS complex detection in ECG Signal. Curr Trends Technol Sci 2013, 2(4), 277-82.

ECG is the graphical recording of the electrical activity of the heart used for clinical diagnosis. The project has been devised to find a method for ECG signal analysis which is simple and has good accuracy and takes less computation time. The initial task for efficient analysis is the removal of noise. It involves the extraction of the required cardiac components by rejecting the background noise. It involves the extraction of the required cardiac components by rejecting the background noise. The ECG signal is very sensitive in nature, and even if small noise is mixed with original signal, the various characteristics of the signal changes. The signal voltage level is as low as 0.5 to 5mV and the frequency components fall in the range of 0.05 to 100Hz. As far as the noise is concerned the muscle movements, main current and ambient electromagnetic interference generate it. Hence filtering remains an important issue, as data corrupted with noise must either be filtered or discarded. The characteristics of the components of the ECG signal P, Q, R, S and T determine the clinical status of the activity of the heart. Detection of R wave in heart signal is easier than other portions of ECG signal due to its structureal form and high amplitude. This paper discusses R-peak and QRS complex detection in ECG signal processing.

21 illus, 2 tables, 10 ref

018064   Srivastava M;Agrawal S K;Das S (Applied Mathematics Dep, Indian Institute of Technology (BH), Varanasi, Uttar Pradesh, Email: subir_das08@hotmail.com) : Adaptive projective synchronization between different chaotic systems with parametric uncertainties and external disturbances. Pramana J Phys 2013, 81(3), 417-37.

The article deals with adaptive projective synchronization between two different chaotic systems with parametric uncertainties and external disturbances. Based on Lyapunov stability theory, the projective synchronization between a pair of different chaotic systems with fully unknown parameters are derived. An adaptive control law and a parameter update rule for uncertain parameters are designed such that the chaotic response system controls the chaotic drive system. Numerical simulation results are performed to explain the effectiveness and feasibility of the techniques.

15 illus, 42 ref

018063   Sharma N;Dahiya H (Physics Dep, Dr B.R. Ambedkar National Institute of Technology, Jalandhar-144 011, Email: dahiyah@nitj.ac.in) : Charge radii of octet and decuplet Baryons in chiral constituent quark model. Pramana J Phys 2013, 81(3), 449-65.

The charge radii of the spin-1/2⁺ octet and spin-3/2⁺ decuplet baryons have been calculated in the framework of chiral constituent quark model (χCQM) using a general parametrization method (GPM). Our results are not only comparable with the latest experimental studies but also agree with other phenomenological models. The effects of SU(3) symmetry breaking pertaining to the strangeness contribution and GPM parameters pertaining to the one-, two- and three-quark contributions have also been investigated in detail and are found to be the key parameters in understanding the non-zero values for the neutral octet (n, ∑⁰, Ξ⁰, Λ) and decuplet (Δ⁰, ∑^*0, Ξ^*0) baryons.

6 tables, 51 ref

018062   Sanctis M D (Fisica Dep, Nacional de Colombia Univ, Bogota (D.C.), Colombia) : Higgs interchange and bound states of superheavy fermions. Pramana J Phys 2013, 81(3), 467-83.

Hypothetical superheavy fourth-generation fermions with a very small coupling with the rest of the Standard Model can give rise to long enough lived bound states. The production and the detection of these bound states would be experimentally feasible at the LHC. Extending, in the present study, the analysis of other authors, a semirelativistic wave equation is solved using an accurate numerical method to determine the binding energies of these possible superheavy fermion-bound states. The interaction given by the Yukawa potential of the Higgs boson exchange is considered; the corresponding relativistic corrections are calculated by means of a model based on the covariance properties of the Hamiltonian. Study the effects given by the Coulomb force. Moreover, authors calculate the contributions given by the Coulombic and confining terms of the strong interaction in the case of superheavy quark bound states. The results of the model are critically analysed.

4 tables, 41 ref

018061   Rastgoo S;Golshan M M (Physics Dep, College of Sciences, Shiraz Univ, Shiraz-71454, Iran, Email: golshan@susc.ac.ir) : Spin-momenta entanglement in moving frames: properties of Von Neumann Entropy. Pramana J Phys 2013, 81(3), 385-93.

The fact that spin-momentum of massive particles become entangled (disentangled) as seen by moving observers, is used to investigate the properties of von Neumann entropy, as a measure of spin-momentum entanglement. To do so, we partition the total Hilbert space into momentum and spin subspaces so that the entanglement occurs between total spin states and total momenta of two spin-1/2 particles. Assuming that the occurrence of spin-momentum states is determined by Gaussian probability distributions, we show that the degree of entanglement ascends for small rapidities, reaches a maximum and diminishes at high rapidity. We further report how the characteristics of this behaviour vary as the widths of distributions change. In particular, a separable state, resulting from equal distribution widths, indeed becomes entangled in moving frames.

3 illus, 29 ref

018060   Prasad A (Physics and Astrophysics Dep, Delhi Univ, Delhi-110 007, Email: awadhesh@physics.du.ac.in) : Time-varying interaction leads to amplitude death in coupled nonlinear oscillators. Pramana J Phys 2013, 81(3), 407-15.

New form of time-varying interaction in coupled oscillators is introduced. In this interaction, each individual oscillator has always time-independent self-feedback while its interaction with other oscillators are modulated with time-varying function. This interaction gives rise to a phenomenon called amplitude death even in diffusively coupled identical oscillators. The nonlinear variation of the locus of bifurcation point is shown. Results are illustrated with Landau-Stuart (LS) and Rossler oscillators.

4 illus, 37 ref

018059   Mu G;Dai Z;Zhao Z (NO, College of Mathematics and Information Science Qujing Normal Univ, Qujing-655 011, People's Republic of China, Email: actuary2010@163.com) : Localized structures for (2+1)-dimensional boiti-leon-pempinelli equation. Pramana J Phys 2013, 81(3), 367-76.

It is shown that Painleve integrability of (2+l)-dimensional Boiti-Leon-Pempinelli equation is easy to be verified using the standard Weiss-Tabor-Carnevale (WTC) approach after introducing the Kruskal's simplification. Furthermore, by employing a singular manifold method based on Painleve truncation, variable separation solutions are obtained explicitly in terms of two arbitrary functions. The two arbitrary functions provide us a way to study some interesting localized structures. The choice of rational functions leads to the rogue wave structure of Boiti-Leon-Pempinelli equation. In addition, for the other choices, it is observed that two solitons may evolve into breather after interaction. Also, the interaction between two kink compactons is investigated.

3 illus, 39 ref

018058   Mandal S (Theoretical Physics Dep, Indian Association for the Cultivation of Science, 2A&2B Raja S.C. Mullick Road, Jadavpur, Kolkata-700 032, Email: mandal.saptarshi1@gmail.com) : On the determination of the mutual exclusion statistics parameter. Pramana J Phys 2013, 81(3), 503-9.

Following the generalized definition of exclusion statistics to infinite-dimensional Hilbert space [Murthy and Shankar, Phys. Rev. Lett. 72, 3629 (1994)] for a single-component anyonic system, we derive a simple relation between second mixed virial coefficient and the mutual exclusion statistics parameters using high-temperature expansion method for multicomponent anyonic system. The above result is derived without working in a specific model and is valid in any spatial dimensions.

15 ref

018057   Liu W;Chen K (NO, College of Mathematics and Statistics, Nanjing Information Science and, Nanjing-210 044, China, Email: wjliu@nuist.edu.cn) : Functional variable method for finding exact solutions of some nonlinear time-fractional differential equations. Pramana J Phys 2013, 81(3), 377-84.

In this paper, we implemented the functional variable method and the modified Riemann-Liouville derivative for the exact solitary wave solutions and periodic wave solutions of the time-fractional Klein-Gordon equation, and the time-fractional Hirota-Satsuma coupled KdV system. This method is extremely simple but effective for handling nonlinear time-fractional differential equations.

39 ref

018056   Khan M A;Poria S (Mathematics Dep, Garhbeta Ramsundar Vidyabhaban, Garhbeta, Paschim Medinipur-721 127, Email: mdmaths@gmail.com) : Projective synchronization of chaotic systems with bidirectional nonlinear coupling. Pramana J Phys 2013, 81(3), 395-406.

This paper presents a new scheme for constructing bidirectional nonlinear coupled chaotic systems which synchronize projectively. Conditions necessary for projective synchronization (PS) of two bidirectionally coupled chaotic systems are derived using Lyapunov stability theory. The proposed PS scheme is discussed by taking as examples the so-called unified chaotic model, the Lorenz-Stenflo system and the nonautonomous chaotic Van der Pol oscillator. Numerical simulation results are presented to show the efficiency of the proposed synchronization scheme.

8 illu, 24 ref

018055   Jha N;Jain S R (High Pressure & Synchrotron Radiation Physics Div, Bhabha Atomic Research Centre, Mumbai-400 085, Email: nandanj@barc.gov.in) : Steady state of a particle in a vibrating box and possible application in short pulse generation of charged paticles. Pramana J Phys 2013, 81(3), 485-90.

In this paper the classical evolution of a particle is studied which bounces back and forth in a 1D vibrating cavity such that the reflection from the wall does not change the speed of the particle. A peculiar behaviour of the particle motion can be seen where the time evolution of the motion shows superposition of linear and oscillatory behaviour. In particular, the parameter range is found in which the particle oscillates between the walls in steady state as if the wall was static and it is showed that for these parameter ranges the particle settles to this steady state for all initial conditions. It is proposed that this phenomenon can be used to bunch charged particles in short pulses where the synchronization proposed in our model should work against the space charge effect in the charged particle bunch.

3 illus, 4 ref

018054   Jai Prakash (Applied Science & Humanities Dep, Buddha Institute of Technology, CL 1, GIDA, Gorakhpur-273 209, Email: jpgkp.2010@rediffmail.com) : Thermoluminescence glow curve involving any extent of retrapping or any order of kinetics. Pramana J Phys 2013, 81(3), 521-33.

Adirovitch set of equations has been modified to explain the mechanisms involved in thermoluminescence (TL) glow curve. A simple model is proposed which explains the occurrence of TL glow curve involving any extent of retrapping or any order of kinetics. It has been observed that the extents of recombination and simultaneous rewrapping decide the order of kinetics involved. TL decay parameters, order of kinetics and initial concentration of trapped electrons per unit volume are evaluated easily and conveniently. It has been observed that retrapping increases with increasing order of kinetics.

3 illus, 3 tables, 49 ref

018053   Ghosh D K;Chatterjee P;Mandal P K;Sahu B (Mathematics Dep, Siksha Bhavana, Visva Bharati Univ, Santiniketan-731 235, Email: biswajit_sahu@yahoo.co.in) : Nonplanar ion-acoustic shocks in electron-positron-ion plasmas: effect of superthermal electrons. Pramana J Phys 2013, 81(3), 491-501.

Ion-acoustic shock waves (IASWs) in a homogeneous unmagnetized plasma, comprising superthermal electrons, positrons, and singly charged adiabatically hot positive ions are investigated via two-dimensional nonplanar Kadomstev-Petviashvili-Burgers (KPB) equation. It is found that the profiles of the nonlinear shock structures depend on the superthermality of electrons. The influence of other plasma parameters such as, ion kinematic viscosity and ion temperature, is discussed in the presence of superthermal electrons in nonplanar geometry. It is also seen that the IASWs propagating in cylindrical/spherical geometry with transverse perturbation will be deformed as time goes on.

6 illus, 56 ref

018052   Ahangari Z;Fathipour M (Electrical Engineering Dep, Science and Research Branch, Islamic Azad Univ, Tehran, Iran, Email: z.ahangari@iausr.ac.ir) : Performance assessment of nanoscale schottky MOSFET as resonant tunnelling device: non-equilibrium green's function formalism. Pramana J Phys 2013, 81(3), 511-20.

Comprehensive study is performed on the electrical characteristics of Schottky barrier MOSFET (SBMOSFET) in nanoscale regime, by employing the non-equilibrium Green's function (NEGF) approach. Quantum confinement results in the enhancement of effective Schottky barrier height (SBH). High enough Schottky barriers at the source/drain and the channel form a double barrier profile along the channel that results in the formation of resonance states. Also for the first time, proposed a resonant tunnelling device based on SBMOSFET in which multiple resonance states are modulated by the gate voltage. Role of essential factors such as temperature, SBH, bias voltage and structural parameters on the feasibility of this device for silicon-based resonant tunnelling applications are extensively studied. Resonant tunnelling appears at low temperatures and low drain voltages and as a result negative differential resistance (NDR) is apparent in the transfer characteristic. Scaling down the gate length to 6 nm increases the peak-to-valley ratio (PVR) of the drain current. As the effective SBH reduces, the curvature of the double barrier profile is gradually diminished. Therefore, multiple resonant states are contributed to the current and consequently resonant tunnelling is smoothed out.

6 illus, 17 ref

017020   Srivastava R (Nanomaterials and Sensors Research Laboratory, Physics Dep, Lucknow Univ, Lucknow-226 007, Email: richadolly@rediffmail.com) : Temperature sensor based on nano-sized zinc oxide synthesized via drop wise method. Int J pure appl Sci Technol 2013, 14(1), 9-15.

Nano-sized ZnO was synthesized through the hydroxide precipitation using drop wise method. The variations in resistance of sensing pellet at different temperatures were recorded. The relative resistance was decreased linearly with increasing temperatures over the range, 150 ρC-260 ρC. The activation energy of ZnO calculated from Arrhenius plot was found 0.007eV. Temperature response in terms of the relative variation, ΔR, of sensor resistance to a given temperature was measured. Sensing element has maximum average sensitivity 0.33%/°C to temperature. SEM and XRD of the sensing material were studied Scanning electron micrographs show that synthesized zinc oxide is in the form of nanosheets. Minimum average thickness of ZnO nanosheets is found to be 35nm. Optical characterization of the sensing material was carried out by UV-visible spectrophotometer. By UV-Vis spectra, the estimated value of band gap of ZnO was found 4.59 eV.

7 illus, 21 ref

017019   Roy T;Kar S (Institute of Radio Physics and Electronics, Calcutta Univ, 92, A.P.C. Road, Kolkata-700 009) : Transmission properties of electromagnetic waves through left-handed material: a revisit. IETE J Res 2012, 58(1), 77-82.

The transmission properties of electromagnetic wave through left-handed material (LHM) have been thoroughly investigated. The characterization of signal propagation and evanescent wave amplification through LHM slab has been done on the basis of analytical model equations. The transmission properties have also been addressed from the study of group and phase indices, and anomalous dispersions regions in LHM and right-handed material. Furthermore, the orthogonality of electric and magnetic fields of classical electromagnetism has been seen to be applicable for electric and magnetic plasma buffered by a left-handed (LH) medium.

13 illus, 9 ref

017018   Kumar V;Dhaka S K;Jain A;Chaudhary A; Bhatnagar R;Gupta A;Panwar V;Singh N;Reddy K K (Radio and Atmospheric Physics Lab, Rajdhani College, Delhi Univ, Raja Garden, New Delhi-110 015, Email: dabas.vinay@gmail.com) : COSMIC satellite observations on seasonal variation of pressur at cold point tropopause and its relation with tropical easterly jet over tropical region. Indian J Radio Space Phys 2013, 42(5), 292-7.

The seasonal variation of pressure at cold point tropopause (P-CPT) and its relationship with tropical esterly jet (TEJ) is presented over 30°N-30°S during 2007. A unique data set from COSMIC sattelite with a total number of 2, 14,796 occultations (uniformly spread over land and ocean) is used to present P-CPT. In the tropical region, the P-CPT shows the lowest value (<126> 80-90 mb) during winter and highest (<126> 95-120 mb) during monsoon period in northern hemisphere (NH). It is observed that in the tropical region, 100 mb is a good representative of the tropopause region during NH winter. However, during monsoon, this level shifts in the lower stratosphere mainly over oceans. The noted feature of a significant pressure difference (<126> 20 mb) exists between Indian - Indonesian and African region. In this region, National Center for Environmental Prediction (NCEP) wind data at 100 mb level during summer monsoon period has been analysed and it is revealed that P-CPT is responsible for setting up of the tropical easterly jet with wind speed of <126> -30 ms^-1. High to low pressure variation and the change in wind speed of easterly jet are found to be strongly correlated (correlation coefficient <126> 0.7) in the 10°N-30°N belt.

5 illus, 12 ref

017017   Kakar R;Kanwaljeet Kaur;Gupta K C (NO, DIPS Polytechnic College, Hoshiarpur-146 001, Email: rkakar_163@rediffmail.com ) : Torsional vibrations in a non-homogenous medium over a viscoelastic dissipative medium. Int J pure appl Sci Technol 2013, 14(2), 39-49.

The aim of this paper is to study the propagation of torsional surface wave in a non-homogeneous isotropic medium lying over a dissipative viscoelastic half space. The inhomogeneity taken for the upper layer is hyperbolic. Whittaker's function is used to obtain dispersion equation for the upper free layer. For lower viscoelastic non-homogeneous layer, the analytical solutions for the dispersion relation is obtained by using the method of separation of variables. The obtained dispersion equations are in agreement with the classical result. The numerical calculations have been presented graphically by using MATLAB. This study is helpful to collect the data for the seismic waves produced by superficial explosions.

2 illus, 12 ref

017016   Kakar R;Kanwaljeet Kaur;Gupta K C (NO, DIPS Polytechnic College, Hoshiarpur-146 001, Email: rkakar_163@rediffmail.com ) : Viscoelastic model for longitudinal wave propagation in a non-homogenous viscoelastic filament. Int J pure appl Sci Technol 2013, 14(2), 1-11.

Five parameter viscoelastic model is chosen for studying longitudinal waves in the non-homogeneous viscoelastic rods. The density' ρ', rigidity 'G' and viscosity 'η' of the specimen i.e. rods are space dependent and varies exponentially with distance. The problem is solved with Eikonal equation when the wave equation is approximated using WKB theory. Also, the dispersion of longitudinal waves in homogeneous and non-homogeneous viscoelastic rods is discussed graphically.

3 illus, 19 ref

017015   Eswaraiah S;Ratnam M V;Portnyagin Y I; Merzlyakov E;Bhaskara Rao S V (Physics Dep, Sri Venkateswara Univ, Tirupati-517 502, Email: vratnam@narl.gov.in) : Comparison of mesospheric mean vertical winds between MST radar and empirical model over a tropical station. Curr Sci 2012, 102(9), 1298-1302.

Monthly and seasonal variations of mesospheric vertical winds observed by MST radar located at Gadanki (13.5°N, 79.2°E) are compared with the mesosphere/lower thermosphere (MLT) prevailing empirical wind model. Though there is a difference in the wind magnitude between MST radar observations and the model, the trends match well particularly between 70 and 75 km. The model output has been further used to estimate the diurnal and semi-diurnal amplitudes and phases of tidal components at mesospheric altitudes to assess the contribution of these to the mean mesospheric vertical winds derived from the radar, as the latter does not provide wind information for complete 24 h. From this exercise it has been found that the radar provides reasonably reliable information on mesospheric vertical winds between 70 and 80 km. The observed mesospheric vertical wind is generally upward in all the seasons and is consistent with the general circulation multi-cell features at mesospheric altitudes.

3 illus, 16 ref

017014   Albarakati A M A;Ahmad F (Marine Physics Dep, Faculty of Arabia, Marine Sciences, King Abdulaziz Univ, P.O. Box 20807, Jeddah, 21589, Saudi, Email: aalbarakati@kau.edu.sa) : Variation of the surface buoyancy flux in the red sea. Indian J Geomar Sci 2013, 42(6), 717-21.

In the Red Sea the haline flux is negative throughout the year and its contribution is secondary compared to thermal flux. At the northern region, from October to March, the thermal buoyancy flux is more negative compared to central and southern regions. As a response to the pressure gradient generated by this negative buoyancy flux in winter, a NNW surface current will be induced. During this time, the winds over the southern Red Sea are from SSE. The two forcing factors; buoyancy flux and the wind stress will reinforce the NNW flow. During summer, from June to September, there is a reverse pattern of buoyancy flux to that of winter i.e. a positive buoyancy flux in the north and negative in the central and southern regions. This buoyancy pattern will generate a pressure gradient towards the south resulting in a SSE flow. During this time the winds over the Red Sea are from NNW. The two forcing; pressure gradient towards the south and the NNW winds will favour each other to induce SSE surface current.

4 illus, 1 table, 29 ref

015985   Zhang S;Lu C;Jia T;Sun Z (State Key Laboratory of Precision Spectroscopy, Physics Dep, East China Normal Univ, 3663 North Zhongshan Road, Shanghai-200 062, People's Republic of China, Email: zrsun@phy.ecnu.edu.cn) : Intermediate state absorption enhancement in resonance-mediated (2+1) three-photon excitation process. Indian J Phys 2012, 86(12), 1043-7.

Study the control of intermediate state absorption in resonance-mediated (2+1) three-photon excitation process by shaping the femtosecond pulse with a π phase step modulation under weak laser field. Our results show that the intermediate state absorption can be enhanced, and the coherent enhancement increases with the increase of the pulse intensity and pulse duration. Our analysis indicates that the absorption enhancement results from the absorption reduction of the final state from the intermediate state in the shaped laser field. Furthermore, the effects of the population difference of the final and intermediate states in the unshaped laser field and the transition dipole moment from the intermediate state to the final state on the absorption enhancement are discussed and analyzed.

6 illus, 29 ref

015984   Vora A M (Humanities and Social Science Dep, STBS College of Diploma Engineering, Shri Swami Atmanand Saraswati Vid, Varachha Road, Surat-395 006) : Superconducting state parameters of bulk amorphous alloys. Indian J Phys 2012, 86(12), 1087-91.

Well recognized empty core pseudopotential of Ashcroft is used to investigate the superconducting state parameters viz; electron-phonon coupling strength λ, Coulomb pseudopotential μ*, transition temperature T_c, isotope effect exponent a and effective interaction strength N₀V of some (Ni₃₃Zr₆₇)_1-xV_x (x - 0, 0.05, 0.1, 0.15) bulk amorphous alloys. We have incorporated five different types of local field correction functions, proposed by Hartree (H), Taylor (T), Ichimaru-Utsumi (IU), Farid et al. (F) and Sarkar et al. (S) to show the effect of exchange and correlation on the aforesaid properties. Very strong influence of the various exchange and correlation functions is concluded from the present study. The T_c obtained from local field correction function proposed by Sarkar et al. (S) is in excellent agreement with available theoretical data. Quadratic T_c equation has been proposed providing successfully the T_c values of bulk amorphous alloys under consideration. Also, the present results are found in qualitative agreement with other such earlier reported data, which confirm the superconducting phase in the s bulk amorphous alloys.

5 illus, 1 table, 22 ref

015983   Vijayalakshmi R;Rajendran V (Physics Dep, Presidency College, Chennai, Tamilnadu) : Synthesis and characterization of nano-TiO₂ via different methods. Archiv appl Sci Res 2012, 4(2), 1183-90.

In this paper, author reported the comparison between TiO₂ nanoparticles prepared via two different routes; i) via sol-gel route and ii) by hydrothermal method. It was found that when prepared under the same ambient conditions viz temperature, pressure etc. and keeping all the parameters same viz precursors, mole ratio, solvent etc; the nanoparticles prepared via sol-gel route were highly crystalline and had smaller crystallite size (~ 7nm) as compared to the one prepared by hydrothermal method(~ 17 nm). The crystallinity and the crystallite size were examined by XRD and TEM. The band gap values of the TiO₂ nanoparticles were calculated to be 3.54 and 3.43 eV. Photoluminescence (PL) was also recorded for the two types of particles and results have been analyzed.

13 ref

015982   Ulahannan R T;Renjith R;Bhagyasree J B; Varghese H T;Panicker C Y (Physics Dep, TKM College of Arts and Science, Kollam, Kerala) : Vibrational spectroscopic study of 3-hydroxyacetophenone. Ultra Scient phys Sci-Sect B 2013, 25(1), 1-8.

The FT-IR and FT-Raman spectra of 3-hydroxyacetophenone were recorded and analyzed. The vibrational wavenumbers were calculated using HF and DFT methods. The predicted infrared intensities and Raman activities are reported. The calculated first hyperpolarizability of the title compound is high and the title compound is an attractive object for future studies of non linear optical properties. The calculated HOMO and LUMO energies are -8.868 and -5.469 eV.

1 table, 23 ref

015981   Ulahannan R T;Renjith R;Bhagyasree J B; Krishnakumar G;Varghese H T;Panicker C Y (Physics Dep, TKM College of Aerts and Science, Kollam, Kerala) : Spectroscopic investigations of methyl trimethylacetate. Ultra Scient phys Sci-Sect B 2013, 25(1), 9-16.

FT-IR and FT-Raman spectra of methyl trimethyl acetate were recorded and analyzed. The vibrational wavenumbers were computing at HF and DFT levels. The data obtained from theoretical calculations are used to assign vibrational bands obtained experimentally. The results indicate that DFT method is able to provide satisfactory results for predicting vibrational frequencies. The predicted infrared intensities and Raman activities are reported. The calculated first hyperpolarizability value shows that the title compound is suitable for nonlinear optical studies.

1 table, 27 ref

015980   Thenmoazhi R;Claude A (Physics (PG and Research) Dep, Government Arts College, Dharmapuri) : Rapid crystal growth of benzophenone by low temperature solution growth and its characterization. Archiv appl Sci Res 2012, 4(2), 898-905.

Low temperature solution growth (LTSG) is one of the most efficient and simplest processes which can be employed for crystal growth from solutions. The ease in handling and the readiness in its miscibility with the solvents make it an attractive technique for crystal growth. Most of the chosen solutes are miscible with water and some are with alcohol and ethers. Benzophenone a photoinitiator used in the UV-curing applications in inks, adhesive and coatings, optical fibers and in printed circuit boards. Benzophenone or di-phenyl ketone (CAS No. 119-61-9) with chemical formula (C₆H₅₎₂CO is miscible with ethanol in optimal proportions. The solution is heated for supersaturation well below its boiling point. The supersaturated solution is then taken in a beaker and kept for crystallization. Normal nucleation followed by crystallization happens by evaporation technique at room temperature. A provision for rapid evaporation by astream of uniform hot air flow across the growth chamber enhances the crystallization rate thereby reducing the time required for the growth of crystals. This acceleration of crystal growth is an important prerequisite for the mass crystallization and industrial crystal growth. The crystals are analysed for their surface, structural and spectroscopic characteristics.

5 ref

015979   Terra F S;Mahmoud G M;Mourad L;Tawfik A (Physics Div, Solid State Physics Dep, National Research Center, El-Behooth Str., Dokki, Giza 12622, Egypt, Email: fsterra@yahoo.com) : Structural and electrical properties of In-Se films deposited by thermal evaporation. Indian J Phys 2012, 86(12), 1093-1100.

Indium-selenium films with different thickness values, ranging from 0.13 to 1.63 μm were prepared by thermal evaporation technique. The films were deposited on heated glass substrates kept at 523 K, followed by annealing at the same temperature under high vacuum (10^-5 Torr) for 30 min. The films remained under vacuum for 24 h after evaporation. The structural properties of the films were investigated in terms of X-ray diffraction, energy dispersive X-ray, and scanning electron microscope. The relationship between the room temperature resistivity and the film thickness was investigated. It was found that the resistivity decreased exponentially with film thickness (0.13-0.71 μm) and become constant for values of higher film thickness values. The temperature dependence of the electrical resistivity was also studied in the temperature range 300-420 K for different film thicknesses. Films with a thickness of 0.71 μm were studied for Hall-effect experiment in the temperature range 170-420 K in order to determine Hall charge carriers mobility and charge carriers concentration as well.

13 illus, 6 tables, 34 ref

015978   Tawfik A (Egyptian Center for Theoretical Physics, MTI Univ, Cairo, Egypt, Email: a.tawfik@eng.mti.edu.eg) : Fluctuations of particle yield ratios in heavy-ion collisions. Indian J Phys 2012, 86(12), 1139-46.

Dynamical fluctuations of various particle yield ratios at different center-of-mass energies are studied. Assuming that the particle production in the hadronic final state takes place due to equilibrium chemical processes, the experimental results available so far are compared with the hadron resonance gas (HRG) model taking into account the limited momentum acceptance in heavy-ion collisions experiments against HRG. Degenerated light and conserved strange quarks are presumed at all incident energies. At SPS energies, HRG model provides a good description for the dynamical fluctuations in (K⁺ + K^-)/(π⁺ + π^-) strangeness particle ratio. The dynamical fluctuations of the non-strangeness (p +p)/(π⁺ + π^-) ratio are also studied. To reproduce RHIC results, the quark phase space occupation factor γ have to be assigned should be higher values different than unity. These values are conjectured to manifest the hadronic phase transition to quark-gluon plasma. The results are also compared with string-hadronic cascade and hadron string dynamics models. The dependence on center-of-mass energy seems not to be monotonic.

2 illus, 1 table, 44 ref

015977   Soltani M R;Vahedi J;Sadremomtaz A R; Aboulhasni M R (Physics Dep, Science and Research Branch, Islamic Azad Univ, Tehran, Iran, Email: m.r.soltani.em@gmail.com) : Ising model with staggered Dzyaloshinsky-Moriya interaction. Indian J Phys 2012, 86(12), 1073-7.

Studied the effect of staggered Dzyaloshinsky-Moria (DM) interaction on the ground state phase diagram of the Ising model using variational matrix product state and numerical Lanczos methods. Variational matrix product state results show that the ground state phase diagram of the model consists of two ferromagnetic (FM) and staggered spiral phases in FM case. The quantum corrections of the staggered DM interaction on the ground state phase diagram are determined by a very accurate numerical method and its results confirm our analytic prediction.

4 illus, 29 ref

015976   Sivaiah K;Buddhudu S (Physics Dep, Sr Venkateswara Univ, Tirupati-517 502, Email: ksiva.phy@gmail.com) : Photoluminescence spectra of Sm<. Indian J Phys 2012, 86(12), 1079-85.

Spectroscopic and structural analysis of Sm³⁺ and Dy³⁺: PVP polymer films have been carried out. Emission spectrum of Sm³⁺: PVP film has shown an intense reddish-orange emission at 602 nm (⁴G_5/2 → ⁶H_7/2) with an excitation at 400 nm (⁶H_5/2 → ⁴L_13/2) and this emission has also been noticed when this film was placed under an UV source. From the Dy³⁺: PVP polymer film a yellow emission at 578 nm (⁴F_9/2 → ⁶H_13/2) with an excitation at 387 nm (⁴H_15/2 → ⁴I_13/2) has been observed. For these luminescent ions containing polymer films, dielectric properties have been studied. These films are interestingly found to be unaffected by the moisture in the environment, with the passing of several days, those films are intact, thus it provides an evidence to suggest these films are more stable in their performance as visible color luminescent polymer films.

10 illus, 24 ref

015975   Singh B P;Pandeya A (NO, Govt. P. G. Science College, Rewa, Madhya Pradesh, Email: balendra1982@yahoo.com) : Sunspot numbers in relation with geomagnetic activity. Ultra Scient phys Sci-Sect B 2013, 25(1), 47-50.

Correlated sunspot number (Rz) with geomagnetic Ap and Kp indices for the period 2006 to 2011, and shown to be positively correlated with coefficient of correlation for sunspot no. vs. geomagnetic disturbance index Ap (r = 0.3528) and for sunspot no. vs. geomagnetic activity index Kp (r = 0.3131), and we have concluded that, if number of sunspots increases then there will be an increase in the value of geomagnetic Ap and Kp indices, i.e. geomagnetic disturbance level will be increased, and If number of sunspots decreases then the value of geomagnetic Ap & Kp indices also decreases, and geomagnetic disturbance level will be decreased.

4 illus, 6 ref

015974   Singh B;Gautam R;Srividya Kumar;Vinay Kumar B N;Nongthomba U;Nandi D;Mukherjee G;Santosh V;Somasundaram K;Umapathy S (Inorganic and Physical Chemistry Dep, Indian Institute of Science, Bangalore-560 012, Email: umapathy@ipc.iisc.ernet.in) : Application of vibrational microspectroscopy to biology and medicine. Curr Sci 2012, 102(2), 232-44.

Vibrational microspectroscopic (Raman and infrared (IR)) techniques are rapidly emerging as effective tools to probe the basic processes of life. This review mainly focuses on the applications of Raman and IR micro-spectroscopy to biology and biomedicine, ranging from studies on cellular components in single cells to advancement in techniques for in vitro to in vivo applications. These techniques have proved to be instrumental in studying the biological specimen with minimum perturbation, i.e. without the use of dyes and contrast-inducing agents. These techniques probe the vibra-tional modes of the molecules and provide spectra that are specific to the molecular properties and chemical nature of the species.

10 illus, 3 tables, 75 ref

015973   Sadr S;Azim-Araghi M E;Rahimi M;Dariani R S (Physics Dep, Kharazmi University, Tehran, Iran, Email: so.sadr@ymail.com ) : Effect of gold electrode annealing on gas sensing properties of nano-and microstructures of macroporous silicon. Indian J pure appl Phys 2013, 51(12), 860-3.

This paper presents porous silicon (PS) with nano-and microstructures as carbon dioxide sensing layers. The p-type Si substrate is subjected to PS etching. The PS morphology has been characterized by scanning electron microscope. According to the parameters of electrochemical process, PS layers were found to have a different structure. By using dimethylformamide (DMF) in electrolyte, regular, honeycomb-like and macroporous structures were formed. PS side of the substrate is then coated with a thin layer of gold and annealed at 500°C. These devices, which operate at room temperature, are more sensitive to the applied voltages in CO₂gas. The effect of annealing of gold electrode on current-voltage and response-voltage characteristics of PS has been studied. Our results show that the conductivity and response of PS sensors improve much more when its surface is modified with annealing of gold electrode and also nanostructured PS has greater response than the others.

5 illus, 2 tables, 20 ref

015972   Renjith R;Ulahannan R T;Bhagyasree J B; Varghese H T;Panicker C Y (Physics Dep, TKM College of Arts and Science, Kollam, Kerala) : FT-IR, FT-Raman and computational study of 1,2-cyclohexanediol. Ultra Scient phys Sci-Sect B 2013, 25(1), 97-103.

FT-IR and FT-Raman spectra of 1,2-cyclohexanediol were recorded and analyzed. The vibrational wavenumbers were computing at HF and DFT levels. The data obtained from theoretical calculations are used to assign vibrational bands obtained experimentally. The results indicate that DFT method is able to provide satisfactory results for predicting vibrational frequencies. The predicted infrared intensities and Raman activities are reported. The calculated first hyperpolarizability value shows that the title compound is suitable for nonlinear optical studies. The small differences between experimental and calculated vibrational modes are observed. This is due to the fact that experimental results belong to solid phase and theoretical calculations belong to gaseous phase.

1 table, 23 ref

015971   Renjith R;Ulahannan R T;Bhagyasree J B; Varghese H T;Panicker C Y (Physics Dep, TKM College of Arts and Science, Kollam, Kerala) : FTIR, FT-Raman and quantum chemical calculations of 5-chloromethyl-2-oxazolidinone. Ultra Scient phys Sci-Sect B 2013, 25(1), 39-46.

Optimized molecular structure, vibrational frequencies, corresponding vibrational assignments of the title compound have been investigated experimentally and theoretically using Gaussian09 software package. The geometry optimization has been carried out using HF and DFT levels. The data obtained from vibrational wavenumber calculations are used to assign vibrational bands obtained in IR and Raman spectroscopy of the studied molecule. The calculated infrared intensities and Raman activities are reported. The calculated first hyperpolarizability value shows that the title compound is suitable for nonlinear optical studies. From the HOMO and LUMO analysis, the hardness value of the title compound is 2.868 eV and we conclude that the title compound belongs to hard material

1 table, 45 ref

015970   Rajasekar1 S;Vimalan M;Vijayan N;Joseph P S (Physics Dep, Syed Ammal Engineering College, Ramanathapuram) : Growth and dielectric studies of benzimidazole: A novel organic NLO Material. Archiv appl Sci Res 2012, 4(2), 1022-7.

Benzimidazole single crystal was grown by slow evaporation method and confirmed by PXRD. The grown crystal was characterized by powder X-ray diffractometry (PXRD) and UV-Vis-NIR. The dielectric constant and dielectric loss of the crystal was studied as function of frequencies and the results are discussed.

10 ref

015969   Praharaj M K;Satapathy S;Mishra P R;Mishra S (Physics Dep, ABIT, CDA, Sector-1, Cuttack, Odisha) : Study of acoustical and thermodynamic properties of aqueous solution of NaCl at different concentrations and temperatures through ultrasonic technique. Archiv appl Sci Res 2012, 4(2), 837-45.

Ultrasonic velocity, density, and viscosity have been measured for aqueous solution of NaCl at different concentrations, at different temperatures and at constant frequency (9 MHz). These experimental data have been used to estimate the thermodynamic parameters such as adiabatic compressibility, free length, internal pressure, relaxation time, acoustic impedance, and Gibb's free energy for the solution. This kind of study is important for both humans as well as plants.

17 ref

015968   Pir H;Gunay N;Avci D;Atalay Y (Physics Dep, Art and Science Faculty, Sakarya Univ, 54187 Sakarya, Turkey, Email: yatalay@sakarya.edu.tr) : Quantum chemical computational studies on bisthiourea zinc chloride. Indian J Phys 2012, 86(12), 1049-63.

The molecular geometry and vibrational frequencies of bisthiourea zinc chloride (BTZC) in the ground state have been calculated using the Hartree-Fock (HF) and density functional method (B3LYP) with chosen basis sets. The optimized geometric bond length and bond angles are in good agreement with the experimental data of the compound. The calculation of BTZC which is calculated by HF and B3LYP method, reproduces vibrational wavenumbers with an accuracy which allows reliable vibrational assignments. These methods are proposed as a tool to be applied in the structural characterization of the BTZC. Also, molecular frontier orbital energies, thermodynamic parameters, molecular electrostatic potential, molecular surfaces, nonlinear optical and natural bond orbital analysis of the compound have also been calculated.

4 illus, 7 tables, 41 ref

015967   Pervin S;Rahman M M;Ahmed F;Hakim M A (Physics Dep, Jahangirnagar Univ, Savar, Dhaka 1342, Bangaldesh, Email: mahbub235@yahoo.com) : Investigation of magnetic, dielectric and electrical properties of Ba-hexaferrites. Indian J Phys 2012, 86(12), 1065-72.

Ba-hexaferrites of composition (BaO)_1-x (La₂O₃)_x 5.7 Fe₂O₃, where x = 0.00, 0.04, 0.08 and BaO 5.7 Fe₂O₃ + [0.7 wt% CaO + 0.3 wt% SiO2] were prepared by standard double sintering ceramic technology using magnetite from Cox's Bazar beach sand, Bangladesh. In this work, magnetic, dielectric and electrical properties of Ba-hexaferrites with and without additives have been reported. Measurements of permeability, loss factor, quality factor (Q-factor), resistivity and dielectric constant of the synthesized samples have been carried out. Permeability remains unaltered in the observed frequency range. The loss factor increases with the increase in temperature and additives as well. It has been observed that the loss factor decreases with the increase in frequency. The Q-factor decreases with the increase in temperature and increases with the increase in frequency. The dielectric constant decreases with the increase in frequency. The ac resistivity of Ba-hexaferrites increases with the increase in additive contents.

14 illus, 50 ref

015966   Patil Y S;Chaudhari K G;Murthy K V R;Rao N V P (Applied Physics Dep, MCT'S Rajiv Gandhi Institute of Technology, Versova, Andheri (w), Mumbai) : Synthesis and Effect of Eu Dopant on PL and Crystallites size of lanthanum Phosphate: LaPO₄:Eu<. Archiv appl Sci Res 2012, 4(2), 757-63.

In present paper the effect of dopant on the crystallite size, morphology and the photoluminescence of the sample were also investigated with X-ray spectrometer (XRD), Fourier-transform infrared spectroscopy (FTIR). The phosphors were synthesized using the standard solid state reaction technique and ground using mortar and pestle, fired at 1200°C for 1 hour in a muffle furnace. We have studied the effect of dopants on the Photo luminescent properties of the samples using Spectrofluorophotometer at room temperature. PL emission of undoped LaPO₄ phosphor was observed at 470 nm. Under the excitation of 254nm wavelength, PL emission of doped LaPO₄ phosphor shows peaks at 589, 596, 614 and 622nm with good intensity.

13 ref

015965   Patel U H;Gandhi S A;Patel B D;Modh R D;Patel R H;Yadav J;Desai K R (Physics Dep, Sardar Patel University, Vallabh Vidyanagar, Email: h_patel@yahoo.com) : Synthesis, characterizations, molecular structure and DFT studies of 4-benzylidene-2-(2-chloro-phenyl)-5-methyl-2,4-dihydro-pyrazol-3-one. Indian J pure appl Phys 2013, 51(12), 819-26.

The title molecule 4-benzylidene-2-(2-chloro-phenyl)-5-methyl-2,4-dihydro-pyrazol-3-one, C₁₇H₁₃N₂OCl (I) is synthesized and characterized by IR, NMR and X-ray single crystal diffraction analysis. Molecular geometry, vibrational wave numbers, frontier molecular orbitals and Mulliken charges of the title compound have been calculated using density functional method B3LYP at 6-311g* basis set. Title compound crystallizes in the monoclinic space group P2 1/c with a= 10.343 (3) Angstrom, b= 11.321 (3) Angstrom, c= 12.486 (4) Angstrom, = 92.380 (5)°, V= 1460.8 (7) Angstrom³ and Z= 4. The dihedral angles between the mean plane of chloro phenyl ring, phenyl ring with the mean plane of pyrazole ring are 65.91(15)° and 21.75(17)ø, respectively. After optimization by DFT method, the twisting of the central pyrazole ring with chloro phenyl ring and phenyl ring turns out to be 51.96(16)° and 1.26(14)°, respectively. The drastic differences observed in the dihedral angle calculated after treating the molecule by DFT method support our observations that molecular packing is influenced by the collective effect of weak but significant C-H..N, C-Cl..., C-H...Cl, C-H...O and π-πinteractions in the solid state which are otherwise lacking in isolated state. The optimized geometric bond lengths, bond angles and torsional angles obtained by density function theory (DFT) show good agreement with experimental data. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. Pyrazole oxygen O7 and chloro phenyl carbon C₁₃ act as bifurcated donor and acceptor in half a dozen intermolecular interactions, thereby strengthening the molecular packing.

7 illus, 4 tables, 20 ref

015964   Patel P S (Chemistry Dep, R. R. Mehta College of Science & C. L. Parikh Commerce College, Palanpu, N. Gujarat) : Studies on synthesis and Dyeing Performance of disperse azo dyes based on Schiff base of ninhydrin and 3-amino phenol. Archiv appl Sci Res 2012, 4(2), 846-51.

Some new disperse azo dyes based on Schiff base of ninhydrin and 3-amino phenol were prepared by coupling of various diazo solution of benzene derivatives. The resultant dyes were characterized by elemental analyses as well as IR and NMR spectral studies. The UV-Visible spectral data have also been discussed in terms of structural property relationship. All the disperse azo dyes were applied on polyester textile fibers. The percentage dye bath exhaustion and fixation on the polyester fibers have been found to be very good. The dyied fabrics showed moderate to very good light fastness and washing fastness properties.

17 ref

015963   Parsai N;Mishra A;Shrivastav B D (Sanghvi Innovative Academy, Institute of Technology and Management, Indore-452 010, Email: arsai.neetu@gmail.com) : X-ray K-absorption spectral studies of cobalt (II) hydroxamic mixed ligand complexes. Indian J pure appl Phys 2013, 51(12), 827-32.

X-ray absorption fine structure (XAFS) at the K-edge of cobalt has been studied in some cobalt (II) mixed ligand complexes having hydroxamic acid as one of the ligands. The study can be used to yield useful and important information about the molecular structure of the complexes. The X-ray absorption measurements have been performed at the recently developed BL-8 Dispersive EXAFS beamline at 2.5 GeV Indus-2 Synchrotron Source at RRCAT, Indore, India. The data obtained has been processed using EXAFS data analysis program Athena. From the experimental measurements, the energies of the K absorption edge, chemical shifts, edge-widths, shifts of the principal absorption maximum in the complexes have been estimated. The data obtained from these studies have been utilized to estimate effective nuclear charge.

3 illus, 2 tables, 14 ref

015962   Oluwadare T S;Dawam R R;Achide S A;Olawale O A;Jabil Y Y (Centre for Geodesy and Geodynamics, National Space Research and Develo, , Toro, Bauchi State, Nigeria, Email: temitopeseun@yahoo.co.uk) : Computation of time error in GPS signals: using Schwartzchild time dilation equation. Int J pure appl Sci Technol 2013, 16(2), 10-9.

Global Positioning System (GPS) is a satellite based avigation system that can be used to locate positions anywhere on earth and proper timing determination.The Global Positioning system (GPS) uses accurate, stable atomic clocks in satellites and on the ground to provide world-wide position and time determination. As a result of their motion and being in the earth gravitational field, these clocks are subject to one of the relativity effects known as time dilation and without carefully accounting for this effect, the system would not work. This research work discussed the concept and effect of special and general relativity on GPS navigation as well as using Karl Schwarzschild time dilation equation to estimate time error. Signals exchanged by atomic clocks at different altitudes are subject to general relativistic effects described using the Schwarzschild metric and neglecting these effects would make the GPS error-full. Applying the Kerl Schwarzchild time dilation equation in the obtained GPS data set, as measured at the orbit of the satellite, we found a difference between the proper time and the coordinate time whish gave us the dilated time within the range of 0.7-0.9 seconds. The dilated time for signal to travel from the orbit to the receiving station is what we regarded as Time Error.

2 tables, 12 ref