After the time history of seismic motion is represented by superposition of a series of narrow frequency band wave groups, we obtain a general relation between wave group arrival time and derivative of phase spectra i...After the time history of seismic motion is represented by superposition of a series of narrow frequency band wave groups, we obtain a general relation between wave group arrival time and derivative of phase spectra in the paper. On the basis of the relation, frequency number distribution function of wave group arrival time is completely equivalent to that of phase difference spectra. Under the assumption that phase angles of seismic motionobey uniform distribution ranged from 0 to ─ 2π, a quantitative relation between intensity envelope function of seismic motion and energy distribution function with wave group arrival time has been derived in this paper. The relation illuminates inner links among Fourier amplitude spectra and derivative of phase spectra and intensity envelope function. Some examples given by the paper support the conclusions mentioned above.展开更多
In this work, we present the study of electromagnetic wave propagation through a medium with a variable dielectric function using the concept of Gaussian Beam. First of all, we start with wave equation with which we o...In this work, we present the study of electromagnetic wave propagation through a medium with a variable dielectric function using the concept of Gaussian Beam. First of all, we start with wave equation with which we obtain the solution in terms of the electric field and intensity distributions approximate to Gaussian Function, . With this, we analyze the dependency of r on Gaussian beam distribution spread, the distant from the axis at which the intensity of the beam distribution begins to fall at a given estimate of its peak value. The influence of the optimum beam waist wo and the beam spread on the intensity distribution will also be analyzed.展开更多
Characterization is absolutely necessary and is a must in order to understand and estimate different silver nanoparticle (nm) size in specific group wise manner which corresponds to group wise in number & sizes, a...Characterization is absolutely necessary and is a must in order to understand and estimate different silver nanoparticle (nm) size in specific group wise manner which corresponds to group wise in number & sizes, and their importance and effect on biological tissue and organs with agglomeration for nano toxicological studies in environments, the acute toxicity of colloidal silver nano particles (AgNps) were studied in fresh dissected tissues of Swiss Albino mice and their fetuses. In this manuscript, an attempt is made to demonstrate the synthesis and characterization of silver nano particles with a wide range of sizes (from 2.75 nm up to 1908.2 nm in radius) by reducing silver nitrate powder with polyvinyl pyrollidone in aqueous solutions in the presence of a sodium borohydride stabilizer. The resulting particles were found spherical aggregates with a rough surface and poly dispersity index below 18.26% (>0.783 PDI). The particle optical, cumulative, diluents and electrical conductivity properties were examined by dynamic light scattering and zeta potential but morphology was evaluated after examination by transmission electron microscopy & image-j. Silver nanoparticles were directly coated with polyvinyl pyrollidone with a sodium borohydride stabilizer. Optical properties on a single-particle level were studied by means of auto correlation function measurements. The effective poly dispersity index of the charged silver nanoparticles was low enough to form a colloidal crystal at low ionic strength. Colloidal form is found more toxic than suspended particles in 1.5 molar sodium chloride solution;this shows increase of silver nanoparticles size due to agglomeration, will reduce the toxicity but increase teratogenicity.展开更多
文摘After the time history of seismic motion is represented by superposition of a series of narrow frequency band wave groups, we obtain a general relation between wave group arrival time and derivative of phase spectra in the paper. On the basis of the relation, frequency number distribution function of wave group arrival time is completely equivalent to that of phase difference spectra. Under the assumption that phase angles of seismic motionobey uniform distribution ranged from 0 to ─ 2π, a quantitative relation between intensity envelope function of seismic motion and energy distribution function with wave group arrival time has been derived in this paper. The relation illuminates inner links among Fourier amplitude spectra and derivative of phase spectra and intensity envelope function. Some examples given by the paper support the conclusions mentioned above.
文摘In this work, we present the study of electromagnetic wave propagation through a medium with a variable dielectric function using the concept of Gaussian Beam. First of all, we start with wave equation with which we obtain the solution in terms of the electric field and intensity distributions approximate to Gaussian Function, . With this, we analyze the dependency of r on Gaussian beam distribution spread, the distant from the axis at which the intensity of the beam distribution begins to fall at a given estimate of its peak value. The influence of the optimum beam waist wo and the beam spread on the intensity distribution will also be analyzed.
文摘Characterization is absolutely necessary and is a must in order to understand and estimate different silver nanoparticle (nm) size in specific group wise manner which corresponds to group wise in number & sizes, and their importance and effect on biological tissue and organs with agglomeration for nano toxicological studies in environments, the acute toxicity of colloidal silver nano particles (AgNps) were studied in fresh dissected tissues of Swiss Albino mice and their fetuses. In this manuscript, an attempt is made to demonstrate the synthesis and characterization of silver nano particles with a wide range of sizes (from 2.75 nm up to 1908.2 nm in radius) by reducing silver nitrate powder with polyvinyl pyrollidone in aqueous solutions in the presence of a sodium borohydride stabilizer. The resulting particles were found spherical aggregates with a rough surface and poly dispersity index below 18.26% (>0.783 PDI). The particle optical, cumulative, diluents and electrical conductivity properties were examined by dynamic light scattering and zeta potential but morphology was evaluated after examination by transmission electron microscopy & image-j. Silver nanoparticles were directly coated with polyvinyl pyrollidone with a sodium borohydride stabilizer. Optical properties on a single-particle level were studied by means of auto correlation function measurements. The effective poly dispersity index of the charged silver nanoparticles was low enough to form a colloidal crystal at low ionic strength. Colloidal form is found more toxic than suspended particles in 1.5 molar sodium chloride solution;this shows increase of silver nanoparticles size due to agglomeration, will reduce the toxicity but increase teratogenicity.
