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August 15,2009
Volume 2,Issue 15
Pages 1519-1622
Subject Area:Acoustics,Heat Transfer,Condensed Matter Physics,Crystallology(Crystal Growth,Crystal Chemistry)

Title: Rayleigh correction for resonance frequency of catenary

Authors: ZHANG Pengli, LIN Shuyu, FU Zhiqiang, DONG Jingtuan
PP: 1618～1622
Abstract: Based on the assumption of Rayleigh s approximate theory, the correction for the resonance frequency of vertical vibration of large dimension catenary transformer was carried out, and the expression of corrected frequency was given. The modal analysis for a group of large dimension catenary transformer was done by finite element software ANSYS. Compared with one dimensional theory, the solutions after correction are closer to the solutions of finite element simulation. The corrected solutions have larger scope of application and the frequency is more precise.
Keywords: ultrasonic; large dimension catenary transformer; resonance frequency; frequency modify; modal analysis

Title: Study on thermal property of bi material films based on molecular dynamic simulation

Authors: LIN Meihui, CHEN Minhua, CHEN Yunfei
PP: 1612～1617
Abstract: The thermal property of bi material films was studied using non equilibrium molecular dynamic simulation method. The paper focuses on studying the effects of the film thickness and the regular temperature on the thermal conductivity and the interface thermal resistance of the bi material films. The simulation results demonstrate that the thermal conductivity of the films formed by materials with different potential constant ratios increases with the films thickness, while their interface thermal resistance increases firstly and then decreases when the film thickness is greater than 128 UC. In the temperature range of 40～60 K, the thermal conductivity of the films with different potential constant ratios have different change trends with the increase of temperature, while the corresponding interface resistance decreases with the increase of temperature.
Keywords: calorifics; thermal conductivity; interface thermal resistance; non equilibrium; molecular dynamic

Title: Four dimensions time space metric of perfect gas space outside star s crust

Authors: LAI Xiaoming, BIAN Baomin, YANG Ling, YANG Juan, LI Zhenhua, HE Anzhi
PP: 1604～1611
Abstract: The partial differential equations of perfect gas, which is on one dimensional unsteady dynamics, is non dimensioned, integrating with Π theorem of physical dimension. It comes out the scale factor function form R(t), which is to the non localized gas space out of solid (liquid) stars crust. Using the origin clock as a clock for all the four dimensional space time coordinates, a homogeneous expansion four dimensional space time coordinates system (t, ξ, θ, φ) is established on the space out of stars, which is based on the optical signal appeared on the original point once mentioned by Einstein. A nonlinear radial coordinate conversion is established, by means of both analyzing the relationship between the basic identity of R(t) by reference object element r and total object M(r) in the spherical symmetrical space, and measuring radial coordinate distance Rdξ of object element by the radial coordinate propagation distance dr of optical signal, both of which corresponding to time interval element dt. Ultimately, it comes out the same four dimensions space time interval element as it was under the Schwarzschild metric of general relativity, as well as to prove the Schwarzschild metric is the very case of homogeneous expansion four dimensions space time metric outside stars in vacuum.
Keywords: relativistic cosmology; general theory of relativity; perfect gas; four dimensions time space metric

Title: Research on the permeation mechanism of NaK channel based on a tri state hopping model

Authors: LI Ying, YU Hui, AN Hailong, ZHANG Zhendong, LI Junwei, ZHAN Yong
PP: 1596～1603
Abstract: The three dimensional fine structure of NaK channel was used for building the potential curve of ions combined with channel and the tri state hopping model which demonstrates the permeation process of ions, and current voltage and current concentration relationships in steady state were derived from the master equation. The kinetic characteristics of K+ and Na+ permeation processes in NaK channel were compared. In addition, the transient characteristics of NaK channel were discussed, as well as the characteristic time in relation to the voltage and ion concentration. The results are in good agreement with experiment.
Keywords: biophysics; NaK channel; selectivity; tri state hopping model; master equation

Title: Study on electronic structure of Fe, Ce codoped TiO2 based on the first principles

Authors: ZHAO Qiang, YIN Chunhao, TENG Daoxiang, LI Zebin, LI Fuqiang
PP: 1590～1595
Abstract: The band structure and density of states(DOS) of pure, Fe doped, Ce doped and Fe, Ce codoped anatase phase TiO2 were studied by using the plane wave ultrasoft pseudopotentials method based on the density functional theory. The analysis from the map of band structure and density of states shows that the doping of Fe causes a new energy band which is located in the middle of band gap, the doping of Ce causes the conduction band to downward shift and the doping of Fe/Ce gives a wider middle energy band than the Fe doped, a further left shift for density of states of the 4f electron and a further downward shift for conduction band than the Ce doped, thus reduces the band gap of anatase phase TiO2. It is theoretically predicted that Fe, Ce co doped anatase phase TiO2 will cause the red shift of absorption wavelength and represents an obvious synergy effect in the improvement of catalytic activity of TiO2. The conclusion of theory is the same with that the experiment.
Keywords: semiconductor physics; co doped; first principles; TiO2; Fe; Ce

Title: The relation between X ray wavelength values of Cu target and the fundamental physical constants

Authors: LU Min, BIAN Qing, YIN Shilong
PP: 1585～1589
Abstract: During the application of the X ray diffraction, different wavelength values of Cu target are found out from different publications so that the issue can be discussed in this paper. On the basis of the Rydberg series formula and the wavelength values of Cu target from X ray Transition Database on the website of National Institube of standards and Technology (NIST) in 1998, a simple and practical means is introduced to adjust the X ray wavelength values of Cu target with the fundamental physical constants change. The conclusion is that the values adjusted based on the fundamental physical constants in 2002 and 2006 have reached a same convergence with the X ray wavelength values of Cu target in 1998 provided by NIST after a comparison, which also reflects that the measurement about the fundamental physical constants has become more and more accurate.
Keywords: measuring and testing technologies and instruments; X ray crystallography; ΔE∝R approximate proportional; X ray wavelength values of Cu target; fundamental physical constants

Title: Fabrication and photocatalysis of TiO2 nanotube arrays by a Ti foil anodic oxidation in NH4F containing lactic acid electrolyte

Authors: WANG Yanzong， LI Dapeng, ZHU Wei, HONG Xun, WANG Guanzhong
PP: 1578～1584
Abstract: The paper fabricates high ordered TiO2 nanotube arrays by an anodic oxidation of Ti foils in a NH4F and lactic acid solution. This method makes it possible to prepare quite long TiO2 nautubes with high surface ratio and very thin shells. The inner diameter of the nanotubes varies within 50～148 nm through adjusting the anodic voltage. Long time anodic oxidation could make the nanotube a structure of linked nanorings, or even some independent nanorings The paper also shows that the NH4F concentration within the possible selection in the experiment does not affect the diameter of the nanotubes However, a layer of sediment could be formed on the top of the nanotube arrays when NH4F weight concentration is lower than 0 1% The photocatalysis of the TiO2 nanotube arrays is characterized by the degradation of RhB aqueous solution exposed to ultraviolet light The degradation rate of a 7 cm2 TiO2 nanotube array in a 50 mL solution (0 01 mmol/L) is 47 4 times as fast as that of the dye solution exposed to ultraviolet light alone
Keywords: condensed state physics; TiO2; nanotube; anodic oxidation; photocatalysis

Title: Effects of partial pressure ratio of C2H4/GeH4 on Si1-xGex∶C alloy films

Authors: GE Ruiping, XIA Dongmei, HAN Ping, WU Jun, YU Fei, ZHAO Hong, YU Huiqiang, XIE Zili, XIU Xiangqian, ZHANG Rong, ZHENG Youdou
PP: 1573～1577
Abstract: In this paper, Si1-xGex∶C alloy films have been deposited on Si(100) substrates by chemical vapor deposition (CVD) method. Energy disperse spectroscopy, X ray diffraction, Raman scattering spectra and scanning electron microscope were applied to characterize the Si1-xGex∶C/Si samples. The results show that increasing the flow of the C2H4 and enhancing the partial pressure ratio between C2H4 and GeH4 can improve the surface configuration and lower the roughness of the alloy films. Moreover the alloy films are apt to grow with single crystal tropism with the higher PC2H4/PGeH4. The Si1-xGex∶C alloy layer is p type and the carrier concentration increases from the substrate to the surface.
Keywords: microelectronics and solid state electronics; chemical vapor deposition; Si1-xGex∶C alloy films; PC2H4/PGeH4; carrier concentration

Title: Parallel FDTD for EM scattering from random rough surface with target

Authors: ZENG Hao, GUO Lixin, LI Juan
PP: 1566～1572
Abstract: This paper discusses the electromagnetic (EM) scattering from one dimensional Gauss random rough surface with target using the parallel finite difference time domain (FDTD) method based on message passing interface (MPI) protocol. The parallel programs have run on the cluster of workstation (COW) parallel computing system including several PC nodes, by which the correctness of the algorithm is verified, the accelerating ratio and computational efficiency of the parallel programs are also researched. Comparing with the conventional serial FDTD method, the introduction of the parallel algorithm shows its priority in the computing time to calculate the composite scattering from random rough surface with target.
Keywords: radio physics; random rough surface scattering; parallel finite difference time domain; message passing interface; PC cluster

Title: ZnO thin films of high transmission prepared by evaporation oxidation method

Authors: LI Xue, CHENG Yi, CHI Jingyang, LIANG Hongwei, ZHAO Jianze, SUN Jingchang, HU Lizhong, DU Guotong
PP: 1562～1565
Abstract: In this research, vacuum thermal evaporation is used to prepare transparent ZnO conductive film. In the first step, Zn films were deposited by thermal evaporation technique and then ZnO transparent and conductive films with highly preferred c axis orientation were prepared through thermal oxidation operation. The process, characteristics and influence factors for the growth of the films with preferred growth orientation were discussed. Most importantly, a new method was creatively discovered in oxidizing Zn thin films, that is step by step oxidation method. And the influences of different oxidation methods on ZnO transparent and conductive thin films were investigated. The structure and optical property were tested by X ray diffraction (XRD) and transmitted spectrum. The results show that the quality of ZnO transparent and conductive thin films made by step by step oxidation method is much better than direct　oxidation method, and the highest light transmittance of thin films is over 90%.
Keywords: electron physics; ZnO thin films; evaporation oxidation method; step by step oxidation method; X ray diffraction; low temperature oxidation

Title: Calculation and simulation of the Fresnel diffraction field of a rectangular aperture irradiated by a monochromatic point source

Authors: CHANG Shan, MAO Jiejian, HU Yong, ZHU Pinzhen, PU Zhennan
PP: 1557～1561
Abstract: At first the integral expression of the diffraction field generated from a rectangular aperture irradiated by a monochromatic point source is expressed from the formula of Fresnel Kirchhoff diffraction, then the calculation expressions for Fresnel diffraction field and its peculiar circumstance Fraunhofer diffraction field are deduced. Next the paraxial area diffraction patterns of the corresponding light fields are simulated with the Matlab software from the calculation expressions, and the simulation test verifies that the deduced expressions are effective and reliable. These are conducive to further research related to diffraction theory and technology.
Keywords: optics; rectangular aperture irradiated by a point source; Fresnel diffraction; Fresnel Kirchhoff diffraction formula; Fresnel integral; Fraunhofer diffraction

Title: Study on solvent effect of optical nonlinearities of an organophosphorus fullerene derivative

Authors: WU Rui, LIU Zhibo, ZHANG Xiaoliang, TIAN Jianguo
PP: 1550～1556
Abstract: Optical nonlinearities and optical limiting of an organophosphorus fullerene derivative in four different solvents were determined by the Z scan method by use of a nanosecond pulse laser at 532 nm. Experimental results show that the effect of solvent plays an important role in optical nonlinearities of the organophosphorus fullerene derivative. In the solvent of CS2 which has large optical nonlinearity, the organophosphorus fullerene derivative presents larger reverse saturable absorption and stronger optical limiting than that in other solvents. However, nonlinear refraction of the fullerene derivative in CS2 decreases evidently. The paper studies the optical limiting of the sample, and the results show that the organophosphorus fullerene derivative is a good optical limiting medium, and the solvent is an important factor influencing the optical limiting. By use of a five level model to fit the experimental data, some parameters are obtained, such as excited state absorption and refraction cross sections.
Keywords: optics; reverse saturable absorption; nonlinear refraction; optical limiting; Z scan; organophosphorus fullerene derivative

Title: The controlled adjustment of the coherence length of vertical cavity surface emitting lasers with external optical feedback

Authors: FAN Linlin, WANG Yuncai, WANG Anbang, KONG Lingqin
PP: 1545～1549
Abstract: This paper numerically analyzed the effects on the coherence length of vertical cavity surface emitting lasers (VCSELs) subject to optical feedback and bias current from the external cavities by using Lang Kobayashi rate equations. It is found that the coherence length of VCSELs is decreased depending on the increase of the feedback intensity for long external cavities, but is insensitive to its bias current. Numerical results show that the coherence length of VCSELs can be shortened continuously in a wide range from thirty meters of solitary laser to three millimeters by the optical feedback technique, This property facilitates application in novel measurement technology in which coherence properties are of importance.
Keywords: laser physics； vertical cavity surface emitting lasers; coherence length; optical feedback; nonlinear

Title: Effect of higher order aberrations on visual quality based on individual pseudophakic eye model

Authors: RAO Feng, WANG Zhaoqi, WANG Yan, ZHAO Kanxing, ZUO Tong
PP: 1541～1544
Abstract: Based on the measured corneal topography data and the eye s axial lengths, Spherocylindrical intraocular lens (IOL) is designed with optical design software ZEMAX, and then the individual pseudophakic eye model is constructed. The visual quality at different object distance is analyzed with the established model. It is shown that higher order aberrations deteriorate the visual performance at the designed object distance, but they improve the visual performance at the other object distance. This improvement might provide moderate visual acuity over a large range of object distance. Therefore, specific higher order aberrations may not be corrected in clinic.
Keywords: applied optics; visual optics; individual pseudophakic eye model; modulation transfer function

Title: Design of single photon detection circuits used in quantum communication

Authors: HAN Yuhong, YANG Shu
PP: 1536～1540
Abstract: InGaAs/InP avalanche photodiode (APD) is used in the design of single photon detector of quantum communication. Single photon detector bias generation circuit, single photon signal amplification circuit, single photon signal detection circuit and temperature control module are designed. The sensitivity of detection systems is improved to some extent by using high precision pre amplifier OP37 and sophisticated comparator AD8561, as well as safer and more precise temperature controller chip MAX1978.
Keywords: optics; single photon detection; gate pulse mode; InGaAs/InP avalanche photodiode; quantum communication

Title: Double tunable photonic band gaps in a quasi Λ four level atomic system

Authors: DU Peng, WAN Rengang, KOU Jun, KUANG Shangqi, GAO Jinyue
PP: 1531～1535
Abstract: Double tunable photonic band gaps (PBG) can simultaneously appear when the dispersion property of the medium in a quasi Λ four level atomic system is spatially modulated periodically by a resonant standing light field. Theoretical calculations show that efficient coherent control of two band gaps can be achieved by controlling the intensity of the standing field and the distance of two metastable levels. This scheme can be used as all optical two port signal router having double channels, and has potential application to control the propagations of two light pulses with different central frequencies.
Keywords: optical; double photonic band gaps; standing wave; electromagnetically induced transparency

Title: A novel cluster solid core hybrid guiding photonic crystal fiber

Authors: CHENG Tonglei, CHAI Lu, LI Yanfeng, SONG Zhenming, HU Minglie, WANG Qingyue
PP: 1526～1530
Abstract: The novel cluster solid core hybrid guiding photonic crystal fiber (PCF) is proposed, wherein the PCF is structured by the bismuth silicate glass cores with high refractive index and a silica base. Two light guidance mechanisms, the antiresonant reflecting effect and the total internal reflection, can act simultaneously on the light field in the PCF so that the guiding is only localized in the cluster solid core region. The relationship among the mode field areas of the cluster six core PCF and the cluster eight core PCF and the pump wavelengths and the core diameters are discussed by numerical simulation. The results show that the novel PCF designs have the advantages of equivalent high nonlinearity and large effective mode field area, and can offer a significant potential in high power frequency transform.
Keywords: optical engineering; cluster solid core photonic crystal fiber; high nonlinearity; effective mode field area; hybrid guiding

Title: Application of dynamical continuous time random walk model in effective damping research

Authors: LIN Fang, BAO Jingdong
PP: 1519～1525
Abstract: In this paper, a generalized continuous time random walk model named dynamical continuous time random walk model is proposed. The traditional continuous time random walk model can simulate overdamped systems only; however, the generalized one has overcome this shortage and can be applied to study anomalous transport process with arbitrary power index in arbitrary given potentials. The dynamical continuous time random walk model is applied to investigate the dynamical resonance behavior of an anomalous damped harmonic oscillator and the effective damping. An interesting phenomenon is discovered that the system is always in the underdamped condition when the extraordinary index is smaller than 0.4.
Keywords: statistical physics; anomalous diffusion; continuous time random walk; effective damping; dynamical resonance

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