Vol. 8 & Issue 4 ; Section C : Physical Sciences

Date : August to Oct.2018

 

A theoretical evaluation of enhancement factor Q of electron mobility using different scattering mechanism and 2DEG electron mobility using transport model for quantum well

M.K. Goel , P. K. Verma and L. K. Mishra,[DOI: 10.24214/jcbps.C.8.4.35167.]

  • Abstract

    Using the theoretical formalism of T. T. Hai etal[ Proc.Natl. conf  Theor Phys. 35, 24 (2010)], D. N. Quang etal [J. Appl. Phys. 104, 113711 (2008) and T. Wang etal [J. Appl. Phys. 74, 426 (1993)], we have theoretically evaluated mobility enhancement factor Q using three type of scattering mechanisms for quantum well. We have also evaluated 2DEG electron mobility using LDEG transport model for AlGaAs/GaAs quantum well. The evaluation of mobility enhancement factor Q has been performed using three scattering mechanisms namely (i)  (Top-interface scattering), (ii) QTB  (Top-bottom interface scattering) and (iii) QB (Bottom-interface scattering). The enhancement factor Q is calculated in three different cases: (a) as a function of QW well width L(Aº) keeping correlation length Λ (À) and sheet hole density  PS (cm-2) constant (b) as a function of sheet hole density  PS (cm-2) keeping  L(Aº) and  Λ (À) constant (c) as a function  of correlation length Λ (À) keeping and  L(Aº) constant. In all these three cases enhancement factor Q increase for  and but decrease for. The value of Q is large in  and small for. Using LDEG transport model, we have evaluated POP (polar optical phonon) scattering rate and ACP (acoustic phonon) scattering rate as a function of QW well width. Here, two scattering rate increase and decrease as a function of well width. The magnitude of POP scattering rate is larger than ACP scattering rate. Our obtained results of 2DEG electron mobility as a function of energy difference between first and second sub-bands along with as a function of well width indicate that 2DEG electron mobility increase attain maximum value and then decrease for both the cases. However, the magnitude of electron mobility is larger in first case than in the second case. Our evaluated results of electron energy distribution using Boltzmann distribution function show that energy distribution decrease for equilibrium distribution and also for different fields. Our evaluated results of 2DEG electron scattering rate as a function of electron energy for different well width indicate that scattering rate decrease with electron energyfor all the well width taken. The magnitude is large for small well width and small for large well width. This type of scattering is due to inter sub-bands scattering. Our evaluated results of POP scattering rate as a function of electron energy for bulk electrons, 2DEG and 1DEG show that POP scattering rate increase and decrease with electron energy. Its value is large for bulk electrons and small for 1DEG.The entire evaluation in this paper is based on two approaches namely Variational method and LDEG transport model. The theoretical findings in this paper is quite useful and helpful in order to understand the structural and optical properties of metal organic phase epitaxy-grown multi-QW particularly light emitting diodes (LEDs)

Uranium Adsorption from Aqueous Solution by Trioctylamine Impregnated Polyurethane Foam

Shabaan, Salah M Daher, Ahmed M.; Hussein, A. E. M.; Abdel Aal, M. M. Hosni, A. and Awais, M. S

[DOI: 10.24214/jcbps.C.8.4.36885].

  • Abstract

    The present work indicates that the recovery of uranium from dilute aqueous solutions. The sorption behavior of uranium (VI) was investigated in dilute uranyl nitrate solutions by polyurethane foam impregnated with trioctylamine (TOA) and the fact that extraction is high at use acidic solutions, such as waste acidic leach solutions. The polyurethane foam acts as a cheap and readily available support material for TOA, percentage of solvent and extraction efficiency were evaluated together. The stripping of uranium is easy using H2O; 1M NaOH+0.1M H2SO4; HNO3; Tartaric acid; citric acid and Na2CO3. This method can also be used for concentrated uranium solutions because the TOA-impregnated foam has a high extraction capacity. On the other hand, the effects of some interfering impurities need to be studied in order to apply this method to real solutions.

Experimental Research on Optimization of Array Beamforming Based on Least Squares Support Vector Machine

Guancheng Lin,

[DOI: 10.24214/jcbps.C.8.4.38699.]

  • Abstract

    In order to investigate the performances of main lobe width, sidelobe level, array gain and running time for beamformer based on Least Squares Support Vector Machine (LSSVM) algorithm in real acoustic environment, it sets the constraints of support vector regression equations and proposes the beam optimization method based on least squares support vector machine. Then the optimization model of beamformer based on least squares support vector machine is established, the beam optimization model and the concrete implementation process of beamformer based on the least squares support vector machine is discussed, and the experiments in anechoic water tank are carried out. The experimental results show that the method reduces the computational complexity and decreases the memory occupancy and improves the training speed with the performance of the beamformer substantially unchanged. Compared with the traditional support vector regression beamforming, it has characteristics of fast response for real time requirement and provides a new and effective ways for the optimization design of beamformer.

A theoretical evaluation of super fluid density and superconducting energy gap parameter as a function of reduced temperature (T/TC) for multi-gap superconductors MgB2 and V3Si

Jitendra Kumar, M. K. Singh and L. K. Mishra,

[DOI: 10.24214/jcbps.C.8.4.40013.]

  • Abstract

    Using the theoretical formalism of G. Eilenberger [Z.Phys. A214, 195 (1968)], S P Kruchinin etal [Springer, Dordrecht, p 65-67 (2006)], L Fang etal [Phys. Rev. B80, 140508 (2009)] and X Hu etal [Phys. Rev. B85, 064516 (2012)], we have theoretically evaluated temperature dependent super fluid density and temperature dependent superconducting energy gap for two multi-gap superconductors MgB2 and V3Si. The evaluation is performed by using dimensionless effective interaction constants in the form of inter-band coupling matrix element(λ1112,λ22), densities of states of two- energy bands n1,n2 and Euler’s constant. Our theoretically obtained results show that super fluid densitiesρ1and ρTotal  all decrease with reduced temperature T/Tc for bpth these superconductors. Since the multi-gap superconductors’ possess complex Fermi surfaces and unconventional order parameters therefore one has to vary the different values of inter-band matrix elements and densities of states including the Euler’s constant. On varying the fitting parameters, we observe that the same trend is observed regarding the different values of super fluid densities as a function of reduced temperature T/T for both these superconductors. However, we observed that the values of ρTotal are larger than the values of  ρ1 and ρ for these superconductors, We have also evaluated temperature dependent superconducting energy parameters, Δ1, Δ2 and (Δ)BCS for these superconductors. In this case also, our theoretically obtained results show that Δ1, Δ2 and (Δ)BCS  all parameters decrease with the reduced temperature T/Tc for these superconductors. However, we noticed that the values of Δ1, are larger than the values of Δ2 and (Δ)BCS  for MgB2 but the values of Δ2  are larger than other two  for V3Si . Our theoretically evaluated results are in good agreement with the other theoretical workers.These superconductors have wide applications in manufacturing of superconducting thin film(thin-film industry) and light weight appliances because of lower anisotropy than HTS, larger coherence length (ξ=5nm) and two superconducting gap parameters larger than Nb. It is our firm belief that the theoretical investigation presented in this paper will be quite useful in this direction.

A Theoretical study of hydrodynamic Instability and Quantum turbulence in atomic Bose Einstein Condensate BECs) and evaluation of incompressible and compressible kinetic energy in 2D non-uniform BECs and spin dependent interaction energy for spinor BECs

S. K. Shailendra, P. K. Verma and L. K. Mishra,

[DOI: 10.24214/jcbps.C.8.4.41432.]

  • Abstract

    Using the theoretical formalism of M Tsuboto [arXiv: 1312.0092v2 (cond-mat.quant-gas), 7 Jan 2014], K Fujimoto and M. Tsubota {Phys Rev A 88, 063628 (2013 )}, T-L Hong etal. {Phys. Rev. A80, 023618 (2009)] and M Tsubota {J. Phys. Soc. Jpn. 77, 111006 (2008)}, we have theoretically studied hydrodynamic instability and turbulence in quantum fluids. We have reviewed the physics of classical turbulence (CT) in super fluid helium and quantum turbulence (QT) in atomic BECs, 2D non-uniform BECs, Oscillating BECs and spinor BECs respectively. It has been observed that in the case of classical turbulence (CT) as seen in super fluid helium can be well studied with the help of vortex filament model and use of Biot-Savart law. The quantum turbulence (QT) in the above quantum fluids can be well studied with the help of two coupled GP equation and scaling law analysis. Our evaluated results of incompressible kinetic energy Eikin and compressible kinetic energy  Eckin in the case of 2D non uniform BECs increase and decrease as a function of time t(s), We have also observed that for each time Eckin>Eikin. Our theoretically obtained results of incompressible kinetic energy spectrum for two different range show different power-law behaviour. For 2<k<4, it follows k-5/3 power law which is consistent with Kolmogorov result. For k>10, it obeys k-4 power law as suggested by Soffman. Between these two range of spectral scaling, there is a transitional zone 4<k10, Eikin (k) exhibits no scaling behaviour, Our evaluated results of enstrophy z(k) also increase and decrease with time and follows k-1/3 power law in the first range and k-2 for the second range respectively. In the case of spinor BECs, our evaluated results of spin dependent interaction energy( as a function of kah) also show -7/3 power law behaviour. Similar behaviour has been noticed for the time development of exponent np. Such type of scaling behaviour is observed in the case of magnetic spin glass system. But there is a difference between spin-glass behaviour of spinor BECs and magnetic spin glass. In case of spinor BECs, there is no long range order and spins are randomly oriented. This has been noticed in our evaluation of time development of the spin glass order parameter q(t) which grows as the spin turbulence develops a -7/3 power law. Our theoretically evaluated results are in good agreement with other theoretical workersThe paper reviews the recent important development in the field of CT and QT observed in varieties of BECs. The evaluation has been performed on the basis of quantum hydrodynamics and power law scaling analysis. The results obtained for 2D non uniform BECs and spinor BECs will be quite useful in order to understand the fundamental physcs of turbulence.

Research on LSSVM-based License Plate Character Recognition

LIU Jing

[DOI: 10.24214/jcbps.C.8.4.43341.]

  • Abstract

    Least square support vector machine (LSSVM) is a kind of novel machine learning method. This paper proposes a new method of License plate (LP) character recognition based on least square support vector machine (LSSVM) and singular value decomposition (SVD). Firstly, PL image is preprocessing, Secondly SVD is used to extracts the features of the LP character image, and the singular value feature vector dimension is compressed. The compressed singular value feature vector is used to present the features of each LP image. Then uses LSSVM to train these features and to recognition. Experiment is based on LP image. The experimental results demonstrate the efficency of the proposed approach.

Research on the Evacuation Simulation Model of Large-Scale Gymnasium

Wang Juhai

[DOI: 10.24214/jcbps.C.8.4.44247.]

  • Abstract

    Large gymnasiums are crowded and extremely important. Once emergencies occur, they can cause major economic losses and sometimes cause serious casualties. In recent years, performance-based fire protection designs have been continuously optimized, and computer simulation studies have been used as the main means of performance-based evacuation design. However, at present, the number of gymnasiums has increased, and the problem of safe evacuation has become a center of concern for all walks of life. Therefore, this paper analyzes the characteristics of evacuation of large gymnasiums, and then conducts in-depth research on existing problems in evacuation simulation simulations and proposes them. Corresponding modification suggestions. It is expected to provide guidance personnel with more accurate design when building evacuation models, to make up for previous deficiencies, to help designers better evaluate the safety and reliability of building fire protection design, and to provide reference for ensuring the safety of large gymnasium staff.

A Novel Resonant-Cavity-Enhanced (RCE) Photodetectors principle and performance

Zhao Wei

[DOI: 10.24214/jcbps.C.8.4.44854.]

  • Abstract

    A new Resonant Cavity Enhanced Photodetector is introduced, including fully theoretical deducing & simulation analysis. By comparing with conventional optical Photodetector, It shows that RCE overcome the tradeoff between QE and response speed lies in conventional PD to some extent, the enhanced effect in resonant wavelengths resulting from resonant cavity enables RCE PD with inherent wavelength selectivity which is quite attractive for WDM systems

A theoretical study of BCS-BEC crossover under three different approaches and evaluation of critical temperature TC as a function of detuning parameter, electron concentration n as a function of coupling strength

Biplaw Kumar, N. Dubey and L. K. Mishra,

[DOI: 10.24214/jcbps.C.8.4.45570.]

  • Abstract

    From the theoretical formalism of A N Kocharian etal.[Physica C 364-365, 131 (2001)], T. Domanski and A Donabidowicz [Acta Physica Polonica, 109, 471 (2006)] and Phillip Powell [physics, 569, December 13 (2006)], we have studied BCS-BEC crossover regimes using three approaches (i) from 1D and 2D Hubbard model (ii) from two-channel model for  ystem of ultra-cold alkali atoms (iii) via Feshbach resonance method. In the first approach, our evaluated results of electron concentration n  are obtained as a function of (U/zt). Here U is the coupling strength, z is the coordination number and for 1D, z=2 and for 2D, z=4, t is hopping sites. We have shown the results of n as a function of (U/zt) for both BCS and BEC regimes. In both regimes and for both 1D  and 2D, n decrease as a function of (U/zt) and there is no BEC of electrons both in 1D and 2D for n=1 no matter how strong is . The BCS-BEC crossover in one dimension at  is overall in agreement with the continuum model. In this calculation, it appears that GSCF (general self-consistent field) theory gives a simple relationship between the inhomogeneous BCS order parameter  with  and the corresponding density of bound pairs  in the presence of magnetic field.In the second approach, we have studied BCS-BEC crossover regime by evaluating two parameters 

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Radioactivity and Radiation Hazard levels Assessment of Sediment Samples in South Qusier, Red Sea Coast

Asma Mohammed AL-abrdi, Areej Hazawi and Abdelhamid M. Younis,

[DOI: 10.24214/jcbps.C.8.4.47177.]

  • Abstract

    The activity of 226Ra, 232Th and 40K insediment  samples collected from south Qusier was determined using gamma- ray spectrometry with a high – purity germanium (HPGe) detector.The obtained data indicate that the activity concentrations of most samples are lower than the permissible level for uranium and thorium in Qusierwhile the concentrations of 40K are higher than permissible level. The radium equivalent activity (Raeq) and effective dose rate were estimated for the radiation hazard of the natural radioactivity .The calculated values of The radium equivalent activity (Raeq) and effective dose rate are lower than the recommended limit, so this area safe to be use as tourist infrastructure and medical tourism. 

Tunable Edge Filter as a Smart Energy Saving Window at the Hot Climates of the Baha Region in the Kingdom of Saudi Arabia

Khaled Bashir A. Mashaly,

[DOI: 10.24214/jcbps.C.8.4.47892.]

  • Abstract

    This Study demonstrated a design of one-dimensional photonic crystal (PC) structure consisting of alternate layers of Silicon dioxide (Sio2 ) and Tantalum pentoxide (Ta2O5 ) that blocks infrared light and passes only light of short wavelengths. Results show a new design for optimal edge filter of optical short-wave pass (SWP) filter that can be used as a smart energy saving window. Alaqiq and Almakhwah are hot climate provinces at Albaha region in Kingdom of Saudi Arabia. They have been taken as examples for this study. The design was done with the computational help of optimization using the “Essential Macleod” software. The mean polarized light mode has been contained a transmittance greater than 98% in both summer and winter solstices in the visible region and more than 40% of the amount of sun energy has entered in winter from the infrared region which has been reflected (stopped) in summer. That results in a 0.025-0.175 µm photonic band gap (PBG) shift in the direction of short wavelengths by increasing the angle of incidence.

Study on the IR Smoke Jamming Effect Simulation and Assessment Method

Yuan Wei,

[DOI: 10.24214/jcbps.C.8.4.49302.]

  • Abstract

    Via analysis of the smoke jamming mechanism against the IR imaging system, an IR smoke extinction model has been set up, and the calculation method has been realized for IR spectrum transmittance value under the smoke jamming condition; impacts of multiple factors (smoke concentration, thickness, etc.) on the smoke jamming effect have been analyzed quantitatively according to the simulation curve, and simulation has been conducted on the basis of the said extinction model, providing certain references to R&D of smoke weapons

SL-RIS-Based Metamaterial Antenna with Mushroom and Interdigital Capacitors

Li Hai Long,

[DOI: 10.24214/jcbps.C.8.4.50310]

  • Abstract

    Novel dual-band metamaterial antenna with varied radiation patterns is presented in this paper. By loading a mushroom cell and interdigital capacitors in the center of a square loop mircrostrip patch, dual resonant frequencies can be excited. Meanwhile, square loop reactive impedance surface (SL-RIS) is used to decrease the resonant frequencies and improve the impedance matching. The antenna can work at 1.82GHz with omnidirectional radiation pattern and 2.45GHz with unidirectional radiation pattern. Good agreement can be observed between the measured and simulated results which validates the correctness of this design

Finite difference time domain analysis of TM waves under PML absorbing boundary conditions

Wei Zhao,

[DOI: 10.24214/jcbps.C.8.4.51119.]

  • Abstract

    Be based on the PML absorbing boundary conditions of wave propagation of TM finite-difference time-domain analyses, and given the two-dimensional situation. take absorbing boundary conditions PML FDTD center differential fraction to where net deduces finally to free space for example. Waves that TM Using FDTD program were written in C language, and the results are analyzed in details