Rayleigh wave dispersion signals are significant to underground investigation.Tradition-ally,uniformed trace spacing is employed in surface wave surveys.In some cases,however,uneven trace spacing is often encountered ...Rayleigh wave dispersion signals are significant to underground investigation.Tradition-ally,uniformed trace spacing is employed in surface wave surveys.In some cases,however,uneven trace spacing is often encountered because of the limitations of the site condition.In order to study the influence of uneven trace spacing on the dispersion data construction of Rayleigh waves,data acquisi-tion is performed based on a 2.5D field layout with a linear array of geophones fixed and a mobile source.The observation direction controls the trace spacing of the measurement.The final results demonstrate that the trace nonuniformity has significant influence on the Rayleigh wave dispersion feature constructed.When the observation angle is over 45o,the dispersion image will be too distorted to extract dispersion data correctly.展开更多
The indirect voltammetric determination of trace sulfate (2.0×10^(-6)～4.0×10^(-5) mol/L ) with the adsorptive complex wave of lead(Ⅱ)-tetrakis (4-trimethylammonium phenyl) porphyrin (PbTTMAPP) is reported....The indirect voltammetric determination of trace sulfate (2.0×10^(-6)～4.0×10^(-5) mol/L ) with the adsorptive complex wave of lead(Ⅱ)-tetrakis (4-trimethylammonium phenyl) porphyrin (PbTTMAPP) is reported.This method has been used for the analysis of natural waters with satisfactory results.展开更多
As an effective means to actively modify the ionosphere, chemical release can produce artificial ionospheric holes as a consequence of ionization depletion, which can greatly impact on radio wave propagation. In this ...As an effective means to actively modify the ionosphere, chemical release can produce artificial ionospheric holes as a consequence of ionization depletion, which can greatly impact on radio wave propagation. In this paper, on the basis of the pre-study results on ionospheric disturbances produced by some representative chemical releases, the radio waves propagation effects of ionospheric holes that are produced by two different release species, water （H2O） and sulfur hexafluoride （SF6）, had been investigated and simulated by the three-dimensional （3-D） numerical ray tracing. The results show that 1 the appearance of various artificial ionospheric holes can lead to certain decrease of critical frequency in the ionosphere, and 2 when the wave frequency exceeds the critical frequency, the rays should be multiple reflections or penetrate through the ionospheric hole and focus afterwards with the focus altitude elevated for higher frequencies. This work may provide the necessary theoretical support for chemical release experiments and the evaluation of radio wave propagation effects.展开更多
Based on the quasi-geostrophic vorticity equation, the present peper simulates the water mxing process in the formation Of ocean shear waves using large eddy simulation methods. From Lagrangian tracing, we study the o...Based on the quasi-geostrophic vorticity equation, the present peper simulates the water mxing process in the formation Of ocean shear waves using large eddy simulation methods. From Lagrangian tracing, we study the ocean shear wave's changing from wave character to vortex character. The distance between tracer groups increases near the ocean shear wave area, and decreases between ocean shear waves. The tracers that are uniformally distributed in space do not retain the uniform character in the mixing process. The frequency shift of the perturbation waves is caused by their nonlinear interaction. The wave number ratio and phase lag of the initial perturbation waves affect the mixing process, but the results show little difference. The increase of the viscosity coefficient will restrain the mixing process.展开更多
It has been argued in Part I that traditional expression of multidimensional group velocity used in meteorology is only applicable for isotropic waves. While for anisotropic waves, it cannot manifest propagation of wa...It has been argued in Part I that traditional expression of multidimensional group velocity used in meteorology is only applicable for isotropic waves. While for anisotropic waves, it cannot manifest propagation of waves group along the trajectory of a reference wave point, and varies with rotation of coordinates. The general mathematical expression of group velocity which may be used also for anisotropic waves has been derived in Part I. It will be proved that the mean wave energy, momentum and wave action density are all conserved as a wave group propagates at the general group velocity. Since general group velocity represents the movement of a reference point in either isotropic or anisotropic wave trains, it may be used to define wave rays. The variations of wave parameters along the rays in a slowly varying environment are represented by ray-tracing equations. Using the general group velocity, we may derive the anisotropic ray-tracing equations, which give the traditional ray-tracing equations for isotropic waves.展开更多
Ray tracing study of electromagnetic ion cyclotron （EMIC） waves is conducted based on a realistic plasma density model. The simulation result shows that EMIC waves propagate away from the equatorial source region to...Ray tracing study of electromagnetic ion cyclotron （EMIC） waves is conducted based on a realistic plasma density model. The simulation result shows that EMIC waves propagate away from the equatorial source region to higher latitudes basically along geomagnetic field lines, and are reflected at the region where their frequency matches the local bi-ion frequency. H＋ band suffers H＋-He＋ bi-ion frequency reflection at lower latitudes, whereas He＋ band suffers He＋-O＋ bi-ion frequency reflection at higher latitudes. Moreover, the concentration of heavy ions slightly affects the bi-ion frequencies and then slightly determines the reflection location of ray paths of EMIC waves. The current results present the first detailed study on the propagation characteristics of EMIC waves associated with bi-ion frequencies.展开更多
基金supported by the "973-Project" (No. 2007CB714405)LIESMARS Special Research Funding,LOGEG Research Founding (No. 2008-02-08)the Key Laboratory of Precision Engineering & Industry Surveying,State Bureau of Surveying and Mapping
文摘Rayleigh wave dispersion signals are significant to underground investigation.Tradition-ally,uniformed trace spacing is employed in surface wave surveys.In some cases,however,uneven trace spacing is often encountered because of the limitations of the site condition.In order to study the influence of uneven trace spacing on the dispersion data construction of Rayleigh waves,data acquisi-tion is performed based on a 2.5D field layout with a linear array of geophones fixed and a mobile source.The observation direction controls the trace spacing of the measurement.The final results demonstrate that the trace nonuniformity has significant influence on the Rayleigh wave dispersion feature constructed.When the observation angle is over 45o,the dispersion image will be too distorted to extract dispersion data correctly.
文摘The indirect voltammetric determination of trace sulfate (2.0×10^(-6)～4.0×10^(-5) mol/L ) with the adsorptive complex wave of lead(Ⅱ)-tetrakis (4-trimethylammonium phenyl) porphyrin (PbTTMAPP) is reported.This method has been used for the analysis of natural waters with satisfactory results.
基金Supported by the National Natural Science Foundation of China (60701020)the China Post-Doctoral Science Foundation (20080430988,200801321)the Fundamental Research Funds for the Central Universities (3103001)
文摘As an effective means to actively modify the ionosphere, chemical release can produce artificial ionospheric holes as a consequence of ionization depletion, which can greatly impact on radio wave propagation. In this paper, on the basis of the pre-study results on ionospheric disturbances produced by some representative chemical releases, the radio waves propagation effects of ionospheric holes that are produced by two different release species, water （H2O） and sulfur hexafluoride （SF6）, had been investigated and simulated by the three-dimensional （3-D） numerical ray tracing. The results show that 1 the appearance of various artificial ionospheric holes can lead to certain decrease of critical frequency in the ionosphere, and 2 when the wave frequency exceeds the critical frequency, the rays should be multiple reflections or penetrate through the ionospheric hole and focus afterwards with the focus altitude elevated for higher frequencies. This work may provide the necessary theoretical support for chemical release experiments and the evaluation of radio wave propagation effects.
文摘Based on the quasi-geostrophic vorticity equation, the present peper simulates the water mxing process in the formation Of ocean shear waves using large eddy simulation methods. From Lagrangian tracing, we study the ocean shear wave's changing from wave character to vortex character. The distance between tracer groups increases near the ocean shear wave area, and decreases between ocean shear waves. The tracers that are uniformally distributed in space do not retain the uniform character in the mixing process. The frequency shift of the perturbation waves is caused by their nonlinear interaction. The wave number ratio and phase lag of the initial perturbation waves affect the mixing process, but the results show little difference. The increase of the viscosity coefficient will restrain the mixing process.
文摘It has been argued in Part I that traditional expression of multidimensional group velocity used in meteorology is only applicable for isotropic waves. While for anisotropic waves, it cannot manifest propagation of waves group along the trajectory of a reference wave point, and varies with rotation of coordinates. The general mathematical expression of group velocity which may be used also for anisotropic waves has been derived in Part I. It will be proved that the mean wave energy, momentum and wave action density are all conserved as a wave group propagates at the general group velocity. Since general group velocity represents the movement of a reference point in either isotropic or anisotropic wave trains, it may be used to define wave rays. The variations of wave parameters along the rays in a slowly varying environment are represented by ray-tracing equations. Using the general group velocity, we may derive the anisotropic ray-tracing equations, which give the traditional ray-tracing equations for isotropic waves.
基金supported by National Natural Science Foundation of China(Nos.40925014,41204114,and 41274165)the Aid Program for Scienceand Technology Innovative Research Team in Higher Educational Institutions of Hunan Province,Chinathe Construct Program of theKey Discipline in Hunan Province,China
文摘Ray tracing study of electromagnetic ion cyclotron （EMIC） waves is conducted based on a realistic plasma density model. The simulation result shows that EMIC waves propagate away from the equatorial source region to higher latitudes basically along geomagnetic field lines, and are reflected at the region where their frequency matches the local bi-ion frequency. H＋ band suffers H＋-He＋ bi-ion frequency reflection at lower latitudes, whereas He＋ band suffers He＋-O＋ bi-ion frequency reflection at higher latitudes. Moreover, the concentration of heavy ions slightly affects the bi-ion frequencies and then slightly determines the reflection location of ray paths of EMIC waves. The current results present the first detailed study on the propagation characteristics of EMIC waves associated with bi-ion frequencies.
