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ISSN 1674-2850
CN 11-9150/N5
 
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February 15,2010
Volume 3,Issue 3
Pages 210-319
Subject Area:Electrodynamics,Condensed Matter Physics,Heat Transfer,Applied Optics
 
Title: Study on thermo hydro mechanical coupling mathematical model of saturated rocks
Authors: LIU Shanli
PP: 314~319
Abstract: In oil mining operations by water injection in high pressure, the permafrost by melting and freezing, and the nuclear waste project in rock mass, the density of rock medium will be changed when the geological environmental conditions (such as internal temperature, pressure, etc) have a more dramatic change. Based on understanding and studying the thermo hydro mechanical (THM) coupling problem of such rock mass, the density of liquid solid medium is considered as a parameter changing with temperature and pressure, the heat source produced by the viscous dissipation and the stream flow source made by temperature gradient are reflected in the process of the THM coupling, then the saturated rocks coupling model is derived by considering the changes of medium density.
Keywords: hydraulic engineering; saturated rocks; coupling; thermo hydro mechanical; mathematical model
 
Title: Hydro mechanical coupling analysis of fractured rock mass with changeable transmissibility coefficient
Authors: CHEN Jingyun, LIU Zhongqiu, LIU Ming
PP: 309~313
Abstract: As the connection bridge between seepage field and stress field, transmissibility coefficient plays an important role in hydro mechanical coupling analysis. According to the forced state of rock mass, transmissibility coefficient was defined as the function of stress and strain which can reflect the evolution law of it. Regarding the fractured rock mass as continuous porous media, and built the model of hydro mechanical coupling, then compiled subroutine of USDFLD by use of second development interface of ABAQUS, dynamic change of transmissibility coefficient was realized. Applying the program to a water diversion tunnel excavation project can reflect ‘indirect coupling’ effect. The calculation result is more consistent with the actual project situation, and provides theoretical reference for engineering design and construction.
Keywords: seepage mechanics; hydro mechanical coupling; second development; transmissibility coefficient; ABAQUS
 
Title: Integral description of the spherical gravitational field
Authors: LEI Jiazhi, GENG Biao, XIA Hui, LEI Jiaqiang
PP: 304~308
Abstract: Although Newton\'s law of gravitation gives the general expression, but in fact the law of gravity is difficult to understand, and it has some insurmountable flaws. This research is based on Newton\'s law of universal gravitation, using the triple integral tool of space to get some of the conclusions of sphere gravitational field, and then proceeds to consider the gravitational field at any point in space produced by the spherical shell from these findings, and draws the appropriate conclusions.
Keywords: space physics; spherical shell; the law of universal gravitation; gravitational field; integral
 
Title: Composite element method for the free vibration analysis of beams with variable cross-section: numerical simulation
Authors: LV Zhongrong, XIE Jinrong, LIANG Wanyi, WANG Shuang, LIU Liang
PP: 299~303
Abstract: A brief introduction to composite element method (CEM) is given and it is used to analyze the free vibrations of cantilever beams with variable cross-section in this paper. Comparison is made for the results using the CEM, finite element method (FEM) and other analytical methods. It is further verified by the results from ANSYS. The results show that the CEM has the advantages of computational efficiency and high accuracy.
Keywords: finite element analysis; natural frequencies; composite element method; beams with variable cross-section; free vibration
 
Title: Fatigue reliability analysis of crystallographic orientation in single crystal turbine blade
Authors: LIU Dashun, HOU Naixian, YU Qingmin, YUE Zhufeng
PP: 293~298
Abstract: Based on the single crystal plastic theory and the linear life prediction model, the Monte Carlo method has been presented to analyze the influence of turbine blade crystal orientation on the single crystal blade life. The results show that the distribution of blade crystal orientation is 3 parameter lognormal distribution. Furthermore, the distribution of the single crystal blade life according with 3 parameter Weibull distribution is obtained, using the Monte Carlo method. The method presented here is useful for designing turbine blade at a certain cycle life.
Keywords: solid mechanics; reliability; Monte Carlo method; crystallographic orientation; life prediction
 
Title: Research and application on orthogonality of the polynomial basis function in element free method
Authors: ZHOU Liming, MENG Guangwei, LI Feng, ZHAO Yunliang
PP: 284~292
Abstract: By studying the orthogonality of the basis function in the element free method, the shape functions, obtained by using the orthogonal basis function, have been proved to be identical to that of using the polynomial basis function, and their first and second order derivatives also have the same property. The orthogonality of the basis function does not affect the precision of the solution of the element free method, however, it can change a matrix into a triangular matrix, which makes it easier to solve the inverse matrix, and it can reduce the computing time, and make the element free method more practical. Computational examples were used to illustrate the conclusion.
Keywords: solid mechanics; element free method; moving least square; orthogonal basis function; weight function
 
Title: The application of wavelet transform to nondestructive testing signal from rockbolt supporting system
Authors: LIU Hongyan, WANG Jiyan, ZHAO Yucheng
PP: 279~283
Abstract: In this paper based on characteristic of nondestructive testing signal from rockbolt supporting system, the wavelet transform(WT) was used to divide original signal into different bandwidth and filter the unnecessary bandwidth signals. Meanwhile, the Mallat reconstruction algorithm, which can filter the signal with noise efficiently while holding the characteristics of the original, was brought forward to gain the signal without noise. At last, the transforming result shows that it would make the system run more precisely and stably in the testing to the quality of rockbolt supporting system.
Keywords: solid mechanics; rockbolt supporting quality; testing; wavelet transform
 
Title: Deep anti sliding stability analysis of gravity dam based on indirect method
Authors: CHEN Junpeng, REN Qingwen, YANG Zhihui, CHEN Weiqing
PP: 273~278
Abstract: In this paper, the definition, theory and means of strength reserve method which is included in indirect method were introduced. Non convergent judgment method and mutation judgment method of unstable state of the dam foundation system were also summarized. Then the characteristics of Drucker Prager(D P) yield criterion in ABAQUS were concluded in the paper. Based on these characteristics, the conversion formula of shear parameters between Mohr Coulomb(M C) and Drucker Prager yield criterion in ABAQUS software was given according to the plane strain problem. Finally the deep anti sliding stability analysis of a gravity dam with complicated geological conditions was carried out based on the elastic plastic FEM theory, the strength reserve method, and ABAQUS software. By non convergent judgment method, displacement mutation judgment method and judging the equivalent plastic strain zone distribution, the safety coefficients of deep anti sliding stability and the slide mode of the dam were given.
Keywords: hydraulic structure; deep anti sliding stability; strength reserve method; elastic plastic finite element method; gravity dam
 
Title: Study on bifurcation of multi pulses homoclinic orbits in a system containing multi scale variables
Authors: YUE Baozeng
PP: 265~272
Abstract: The paper studied an extensive numerical exporation of delicate global dynamics of the multi pulses homoclinic orbits in an one kind of dyanamic system containing multi scale variables. A careful analyisis of the scenario of the global fifuircation diagram suggests that the dynamics of self repliating system is related to a hierarchy structure of dolding bifurcation branches in parameter regions. The numerics suggests the Bogdanov Takens points together with a presence of a horn of parameter values emanates from the particular codim 2 homoclinic orbit play a central role for global bifrcatiion of periodic orbits and the homoclinic solutions and the complex chaotic dynamics. Numerical simulation also reveals the existence of the mkulating two pulses or multi pulse, which companying the procedure of puilse self rplicaing and splitting in reation diffusion systems.
Keywords: dynamics and control; global bifurcation; patterns; homoclinic orbits; pulses; hierarchy structure
 
Title: Maxwell's electrostatics theory is the mathematical basis for building unified field formula
Authors: XIAO Jun, WU Xianding
PP: 256~264
Abstract: The paper established a unified theory of four kinds of field forces including gravity. By considering the role of the source field on the charged virtual particle cloud existed around the charge being effected, Maxwell s electrostatic interaction theory was used to prove that the gravitational field, nuclear field and weak field are the interaction results in different forms of electrostatic field, and prove that the opposite sex attraction between the same charge is greater than the same sex repulsion, that is leading to the existence of gravitational effects between two neutral objects. The four field forces interaction potential energy and force formulas which the paper derived don t show divergent results at zero distance, and the balance distance exists among the force formulas. When the interaction distance is less than the balance distance, the force changes the direction.
Keywords: electromagnetism; unified field; interaction potential energy; charged virtual particle cloud
 
Title: Theoretical study of gas adsorption on Al doped BN nanotubes
Authors: LIU Xiangdong, LI Feng, ZHAO Mingwen, XIA Yueyuan
PP: 250~255
Abstract: Using density functional theory, explores the stable configurations and electronic structures of Al doped single walled BN nanotubes (BNNTs) and their interactions with gas molecules, such as H2 and CO. It is found that the Al doped BNNTs are more active than the pristine ones, giving rise to either chemical or physical adsorption of CO. More interestingly, the electronic properties of Al doped BNNTs can be greatly modified by the CO adsorption. By contrast, the interaction between Al doped BNNTs and H2 molecule is very weak and the electronic structure modification is unremarkable. Base on these results, Al doped BNNTs is proposed as gas sensitive materials with high selectivity and performance to detect CO gas.
Keywords: condensed matter physics; BN nanotubes; density functional theory; metal doped; gas adsorption
 
Title: Transfer matrix method for analyzing the character of one dimensional photonic crystals
Authors: GUO Lili, LI Xueshuai, SHEN Hongjun
PP: 243~249
Abstract: The band-gap structure of one dimensional photonic crystals is calculated with a transfer matrix method. Reflectivity (transmittance) of one dimensional photonic crystals is analyzed in finite period and that with defect mode and dispersion is also discussed. The properties of light propagation in 1D periodic dielectric structure are discussed, and a new method to accurately measure dielectric index by detecting the defect frequency in one dimensional doped photonic crystal is suggested. It is important to find out the relationship between the band gap and the dielectric constant.
Keywords: photonic crystals; transfer matrix method; band-gap of photonic; reflectivity; transmittance
 
Title: Selectively peeling and transforming of GaAs microtips for the application in SNOM
Authors: LIANG Xiuping, XU Yubo, ZHU Jinxia, HU Lizhong
PP: 239~242
Abstract: A selective peeling and transforming technique of GaAs microtips was introduced in this paper, which could be used for scanning near field optical microscopy (SNOM). By selectively etching the AlGaAs layer of GaAs microtip/AlGaAs sacrificial layer structure grown on GaAs substrate with SiO2 mask windows, independent GaAs microtips were successfully peeled from GaAs substrate and transformed to the emission windows of vertical-cavity surface-emitting laser (VCSEL). Scanning electron microscopy (SEM) images show that the peeled GaAs microtips have smooth surface and are not damaged during the peeling process. This easy process could be employed as peeling of microtips on large scale and the peeled GaAs microtips can not only be used as SNOM prober but also in scanning probe microscopy system.
Keywords: semiconductor technology; wet etching; microtip peeling; transforming; scanning near field optical microscopy
 
Title: A general bio-heat transfer model based on fractal and fractional derivative
Authors: SUN Yifei, CHEN Wen
PP: 231~238
Abstract: This paper makes the first attempt to develop differential equation models of bio-heat transfer by using fractal and space-fractional derivative. The new models are based on the first law of thermodynamics and basic theories of the traditional Pennes model. In order to verify the new models\' validity, a fractional bio-heat transfer model of the skin tissues is presented. Numerical comparison with the corresponding Pennes and some other models shows that the fractional bio-heat transfer model and the corresponding models can behave similarly by proper choice of fractional derivative order. Results from the fractional model are smaller than those from the Pennes model. Moreover, when the fractional derivative order α approaches to 2, the fractional model and the Pennes model observe very similar. It is also worthy to point out that the fractional derivative order of the bio-heat transfer model of the skin tissues falls between 1.85 and 2.00.
Keywords: biophysics; bio-heat transfer; non-Fourier heat conduction; fractal derivative; fractional derivative
 
Title: Molecular dynamic simulation of thermal conductivity of boron nanotubes
Authors: WANG Min, CHEN Yunfei
PP: 245~230
Abstract: Thermal conductivities of (6,6) armchair boron nanotubes with different lengths at temperature 500 K were simulated by means of direct method. The thermal conductivity in an infinite system was calculated from the extrapolation method. Simulation results demonstrated that the (6,6) boron nanotubes have a high thermal conductivity, and it increases with the length of the nanotube. For an infinitely long boron nanotube, the thermal conductivity can reach as high as 4 960.7 W/Km. The high thermal conductivity is due to no boundary scattering and strong and stiff σ bond in boron nanotubes.
Keywords: heat transmission science; boron nanotubes; thermal conductivity; direct method; extrapolation method
 
Title: Analysis on gradient refractive index waveguides based on BPM
Authors: WU Yongfeng, YU Honglin, MA Shengtao
PP: 219~224
Abstract: Gradient refractive index waveguides need to be analyzed, and accordingly study the performance of wavelength division multiplexer (WDM) based on micro electro mechanical systems (MEMS) blazed grating, such is included gradient index waveguides in structure and studied previously. The BPM (beam propagation method) differential equation is deduced in detail, at the same time, its finite difference solution is put forward. According to the solution, the finite difference beam propagation method (FDBPM) algorithm is carried out with laboratory virtual instrument engineering workbench (LabVIEW), one of the graphical programming software. And radial gradient refractive index waveguides whose refractive index profile is offered are simulated and analyzed. The results indicate that there has stable Gaussian distribution light field in the waveguides when the vertical incident light beam is Gaussian beam, and the radius of waist is periodic changed. And the results show that the self focusing focal length of the waveguide is 22 μm.
Keywords: physical optics; gradient refractive index waveguides; beam propagation method; Gaussian beam; LabVIEW
 
Title: Study on fluorescent detection of microflowing solution using laser-processing quartz micro channels
Authors: BAI Zhongchen, QIN Shuijie, WANG Degui
PP: 215~218
Abstract: A novel method which is based on fluorescent detection of immovable and microflowing solution in micro channels is introduced. Moreover, the effect of microflowing solution in micro channels on fluorescent detection is researched in this paper. The experimental results show that receiving fluorescence intensity has been varied in microflowing solution comparing with immovable solution because of unidirectional flow of detecting solution in micro channels. At the same time, fluctuating ranges of receiving fluorescence intensity has been increased, and the whole amplification of receiving fluorescence intensity is laggard in time domain. The new technology based on the study can be applied extensively in bioanalysis and biological detection in micro-scale application.
Keywords: optics; micro channel; laser-processing; fluorescent detection; quartz crystals
 
Title: Monte Carlo simulations on total aberrations before and after LASIK
Authors: WANG Yao, WANG Zhaoqi
PP: 210~214
Abstract: It is a hot research field which statistically analyses on total aberrations, before and after laser in situ keratomilevsis (LASIK), for a set of eyes. In this paper, the data of total aberrations are got from Wave Scan. Then a series of Monte Carlo simulations (including sign simulation, value simulation and meridional frequency simulation) are performed by manipulating each Zernike coefficient (second through sixth-order) of total aberrations. The results are evaluated by modulation transfer function (MTF) ratio. After Monte Carlo simulations, the MTF ratios for pre-LASIK and post-LASIK eyes are both more than 1.0, and the value for post-LASIK eyes are larger than the one for pre-LASIK eyes. The 100 synthetic eyes are got by Matlab, then the same three Monte Carlo simulations are performed. The result is that the MTF ratios are less than 1.0. It is concluded that there is apparent advantage for the complete eyes true aberrations over random aberrations, whether pre-LASIK or post-LASIK, and the ability of adaptive mechanism of human eyes increases after LASIK.
Keywords: visual optics; LASIK surgery; Monte Carlo simulation; modulation transfer function ratio; synthetic eyes