This study proposes a numerically efficient technique for computing the far-field scattered by a spherical target placed near the seabed.The bottom is supposed to be a homogeneous liquid attenuating half-space.The tra...This study proposes a numerically efficient technique for computing the far-field scattered by a spherical target placed near the seabed.The bottom is supposed to be a homogeneous liquid attenuating half-space.The transmitter and receiver are situated at different points of a homogeneous water half-space.The distances between the transmitter,receiver,and object of interest are assumed to be much larger than the acoustic wavelength in water.The scattered far-field is ascertained using Hackman and Sammelmann’s general approach.The arising scattering coefficients of a sphere are assessed using the steepest descent approach.The branch cut contribution is also considered.The obtained formulas for the form-function can be used for acoustically rigid or soft scatterers,as well as elastic targets or spherical elastic shells.Numerical simulations are conducted for an acoustically rigid sphere.Asymptotic expressions for the scattering coefficients allow a decrease in the number of summands in the formula for the target strength and a significant reduction in computational time.展开更多
Fractures play a crucial role in various fields such as hydrocarbon exploration,groundwater resources management,and earthquake research.The determination of fracture location and the estimation of parameters such as ...Fractures play a crucial role in various fields such as hydrocarbon exploration,groundwater resources management,and earthquake research.The determination of fracture location and the estimation of parameters such as fracture length and dip angle are the focus of geophysical work.In borehole observation system,the short distance between fractures and detectors leads to weak attenuation of elastic wave energy,and high-frequency source makes it easier to identify small-scale fractures.Compared to traditional monopole logging methods,dipole logging method has advantage of exciting pure shear waves sensitive to fractures,so its application is becoming increasingly widespread.However,since the reflected shear waves and scattered shear waves of fractures correspond to different fracture properties,how to distinguish and analyze these two kinds of waves is crucial for accurately characterizing the fracture parameters.To address this issue,numerical simulation of wave responses by a single fracture near a borehole in rock formation is performed,and the generation mechanism and characteristics of shear waves scattered by fractures are investigated.It is found that when the dip angle of the fracture surpasses a critical threshold,the S-wave will propagate to both endpoints of the fracture and generate scattered S-waves,resulting in two distinct scattered wave packets on the received waveform.When the polarization direction of the acoustic source is parallel to the strike of the fracture,the scattered SH-waves always have larger amplitude than the scattered SV-waves regardless of changing the fracture dip angle.Unlike SV-waves,the SH-waves scattered by the fracture do not have any mode conversion.Additionally,propagation of S-waves to a short length fracture can induce dipole mode vibration of the fracture within a wide frequency range.The phenomena of shear waves reflected and scattered by the fracture are further illustrated and verified by two field examples,thus showing the potential of scattered waves for fracture evaluation and characterization with borehole observation system.展开更多
By employing a full quantum theory of electron-photon scattering in intense laser fields,we calculate the angularresolved radiation rate of the fundamental wave in Thomson scattering.We investigate the dependence of r...By employing a full quantum theory of electron-photon scattering in intense laser fields,we calculate the angularresolved radiation rate of the fundamental wave in Thomson scattering.We investigate the dependence of radiation rate on Euler angles and elucidate the underlying physical mechanism.The figure-8 profile of the radiation rate within the polarization plane is validated,while its evolution with respect to laser intensity and electron momentum is illustrated.Our findings reveal that in lower-intensity laser fields and for slow electron motion,the angular-resolved radiation rate exhibits distinct dipole emission characteristics.However,significant changes are observed at high laser intensities and/or large electron momenta,leading to pronounced alterations in the angular-resolved radiation rate.Remarkably similar variation patterns can be achieved by proportionally adjusting both laser intensity and electron momentum.展开更多
During daylight laser polarization sensing of high-level clouds(HLCs),the lidar receiving system generates a signal caused by not only backscattered laser radiation,but also scattered solar radiation,the intensity and...During daylight laser polarization sensing of high-level clouds(HLCs),the lidar receiving system generates a signal caused by not only backscattered laser radiation,but also scattered solar radiation,the intensity and polarization of which depends on the Sun’s location.If a cloud contains spatially oriented ice particles,then it becomes anisotropic,that is,the coefficients of directional light scattering of such a cloud depend on the Sun’s zenith and azimuth angles.In this work,the possibility of using the effect of anisotropic scattering of solar radiation on the predictive ability of machine learning algorithms in solving the problem of predicting the HLC backscattering phase matrix(BSPM)was evaluated.The hypothesis that solar radiation scattered on HLCs has no effect on the BSPM elements of such clouds determined with a polarization lidar was tested.The operation of two algorithms for predicting the BSPM elements is evaluated.To train the first one,meteorological data were used as input parameters;for the second algorithm,the azi-muthal and zenith angles of the Sun’s position were added to the meteorological parameters.It is shown that there is no significant improvement in the predictive ability of the algorithm.展开更多
Conventional seismic exploration,mostly based on reflection theory,hardly has accurate imaging results for disaster geologic bodies which have small scale,steep dip,or complex structure.In this paper,we design two typ...Conventional seismic exploration,mostly based on reflection theory,hardly has accurate imaging results for disaster geologic bodies which have small scale,steep dip,or complex structure.In this paper,we design two typical geologic models for analyzing the characteristics of scattered waves in mines for forward modeling by finite difference and apply the equivalent offset migration（EOM）and EOM-based interference stack migration methods to mine prospecting.We focus on the analysis of scatted imaging’s technological superiority to reflection imaging.Research shows：1）scattered imaging can improve fold and make the best of weak scattered information,so it shows better results than post-stack migration imaging and 2）it can utilize the diffraction stack migration method-based ray path theory for mine seismic advanced prediction,so it provides an new efficient imaging method for improving resolution of mine seismic exploration.展开更多
This paper presents a reasonable gridding-parameters extraction method for setting the optimal interpolation nodes in the gridding of scattered observed data. The method can extract optimized gridding parameters based...This paper presents a reasonable gridding-parameters extraction method for setting the optimal interpolation nodes in the gridding of scattered observed data. The method can extract optimized gridding parameters based on the distribution of features in raw data. Modeling analysis proves that distortion caused by gridding can be greatly reduced when using such parameters. We also present some improved technical measures that use human- machine interaction and multi-thread parallel technology to solve inadequacies in traditional gridding software. On the basis of these methods, we have developed software that can be used to grid scattered data using a graphic interface. Finally, a comparison of different gridding parameters on field magnetic data from Ji Lin Province, North China demonstrates the superiority of the proposed method in eliminating the distortions and enhancing gridding efficiency.展开更多
The scattered fields of plane waves in a solid from a cylinder or sphere are critical in determining its acoustic characteristics as well as in engineering applications. This paper investigates the scattered field dis...The scattered fields of plane waves in a solid from a cylinder or sphere are critical in determining its acoustic characteristics as well as in engineering applications. This paper investigates the scattered field distributions of different incident waves created by elastic cylinders embedded in an elastic isotropic medium. Scattered waves, including longitudinal and transverse waves both inside and outside the cylinder, are described with specific modalities under an incident plane wave. A model with a scatterer embedded in a structural steel matrix and filled with aluminum is developed for comparison with the theoretical solution. The frequency of the plane wave ranged from 235 kHz to 2348 kHz, which corresponds to scaling factors from 0.5 to 5. Scattered field distributions in matrix materials blocked by an elastic cylindrical solid have been obtained by simulation or calculated using existing parameters. The simulation results are in good agreement with the theoretical solution, which supports the correctness of the simulation analysis. Furthermore, ultrasonic phased arrays are used to study scattered fields by changing the characteristics of the incident wave. On this foundation, a partial preliminary study of the scattered field distribution of double cylinders in a solid has been carried out, and the scattered field distribution at a given distance has been found to exhibit particular behaviors at different moments. Further studies on directivities and scattered fields are expected to improve the quantification of scattered images in isotropic solid materials by the phased array technique.展开更多
An analytic equation interpreting the intensity of ultrasound-modulated scattering light is derived, based on diffusion theory and previous explanations of the intensity modulation mechanism. Furthermore, an experimen...An analytic equation interpreting the intensity of ultrasound-modulated scattering light is derived, based on diffusion theory and previous explanations of the intensity modulation mechanism. Furthermore, an experiment of ultrasonic modulation of incoherent light in a scattering medium is developed. This analytical model agrees well with experimental results,which confirms the validity of the proposed intensity modulation mechanism. The model supplements the existing research on the ultrasonic modulation mechanism of scattering light.展开更多
Making rural settlements of Mountainous Regions in Western Sichuan as the study objects and using symbolic statistical methods, then combining the case study of Daofu County, the paper analyzes the negative impact of ...Making rural settlements of Mountainous Regions in Western Sichuan as the study objects and using symbolic statistical methods, then combining the case study of Daofu County, the paper analyzes the negative impact of the scattered rural settlements on infrastructure construction, farmers＇ income increase and mountain ecological reconstruction in mountainous regions of western Sichuan. The results indicate that economic density is positively related to both rural settlements density （R^2=0.73） and rural population density （R^2=0.77）, and it is the same for relationship between towns density and rural settlements density （R^2=0.88） and between towns density and economic density （R^2=0.71）, and the scattered distribution pattern of the rural settlements and shortage of economic centers is a major factor to the lagged socioeconomic development. On the eco-economic zoning to Daofu County, the paper indicates the spatial distribution model and the industrial development model of the rural settlements need to be changed, and rural population should be concentrated in larger rural settlements with development of off-farm industries while infrastructure construction is to reinforced.展开更多
A new detection system in scanning electron microscope,which filters in energy and detects the backscattered electrons close to the microscope axis,is described.This technique ameliorates the dependence of the back.sc...A new detection system in scanning electron microscope,which filters in energy and detects the backscattered electrons close to the microscope axis,is described.This technique ameliorates the dependence of the back.scat tering coefficient on atomic number,and suppresses effectively the relief contrast at the same time.Therefore this new method is very suitable to the composition analysis.展开更多
Scattered storage means an item can be stored in multiple inventory bins. The scattered storage assignment problem based on association rules in Kiva mobile fulfillment system is investigated, which aims to decide the...Scattered storage means an item can be stored in multiple inventory bins. The scattered storage assignment problem based on association rules in Kiva mobile fulfillment system is investigated, which aims to decide the pods for each item to put on so as to minimize the number of pods to be moved when picking a batch of orders. This problem is formulated into an integer programming model. A genetic algorithm is developed to solve the large-sized problems. Computational experiments and comparison between the scattered storage strategy and random storage strategy are conducted to evaluate the performance of the model and algorithm.展开更多
In the paper, firstly, based on new non-tensor-product-typed partially inverse divided differences algorithms in a recursive form, scattered data interpolating schemes are constructed via bivariate continued fractions...In the paper, firstly, based on new non-tensor-product-typed partially inverse divided differences algorithms in a recursive form, scattered data interpolating schemes are constructed via bivariate continued fractions with odd and even nodes, respectively. And equivalent identities are also obtained between interpolated functions and bivariate continued fractions. Secondly, by means of three-term recurrence relations for continued fractions, the characterization theorem is presented to study on the degrees of the numerators and denominators of the interpolating continued fractions. Thirdly, some numerical examples show it feasible for the novel recursive schemes. Meanwhile, compared with the degrees of the numera- tors and denominators of bivariate Thiele-typed interpolating continued fractions, those of the new bivariate interpolating continued fractions are much low, respectively, due to the reduc- tion of redundant interpolating nodes. Finally, the operation count for the rational function interpolation is smaller than that for radial basis function interpolation.展开更多
Aiming at the problem of underwater polarized laser scattering caused by underwater suspended particles, the equivalent spherical particle Mie scattering theory simulation method is used to study the polarization char...Aiming at the problem of underwater polarized laser scattering caused by underwater suspended particles, the equivalent spherical particle Mie scattering theory simulation method is used to study the polarization characteristics of underwater scattered light. The relationship between underwater suspended particle characteristics and optical characteristics is analyzed, and the effects of particle size, polarization characteristics of incident light, and angle of incidence on the degree of polarization of forward and backward scattering light are studied. The results show that: When the incident light is natural light, the degree of polarization of scattered light is very low at the forward-scattering angle, which increases with the increase of the scattering angle, but changes frequently with the increase of the particle size. When the incident light is linearly polarized, the degree of linear polarization of the scattered light is related to the azimuth Angle. The degree of circular polarization is largely unaffected by particle size.展开更多
The maritime tropospheric duct is a low-altitude anomalous refractivity structure over the ocean surface,and it can significantly affect the performance of many shore-based/shipboard radar and communication systems.We...The maritime tropospheric duct is a low-altitude anomalous refractivity structure over the ocean surface,and it can significantly affect the performance of many shore-based/shipboard radar and communication systems.We propose the idea that maritime tropospheric ducts can be retrieved from ocean forward-scattered low-elevation global positioning system（GPS） signals.Retrieval is accomplished by matching the measured power patterns of the signals to those predicted by the forward propagation model as a function of the modified refractivity profile.On the basis of a parabolic equation method and bistatic radar equation,we develop such a forward model for computing the trapped propagation characteristics of an ocean forward-scattered GPS signal within a tropospheric duct.A new GPS scattering initial field is defined for this model to start the propagation modeling.A preliminary test on the performance of this model is conducted using measured data obtained from a 2009-experiment in the South China Sea.Results demonstrate that this model can predict GPS propagation characteristics within maritime tropospheric ducts and serve as a forward model for duct inversion.展开更多
By using the theories on Stokes multicolored water waves and taking the two- layer ocean as a basic model of stratified ocean, the paper analyzes the problems related to the effects of the nonlinear water wave on offs...By using the theories on Stokes multicolored water waves and taking the two- layer ocean as a basic model of stratified ocean, the paper analyzes the problems related to the effects of the nonlinear water wave on offshore structures. A mathematical expression is presented to describe second order wave radiation conditions. Using integral principle, the analytical integral solutions are given to evaluate second order scattered wave loads on general vertical circular cylinders in the two-layer ocean, and the special recurrence formulas for infinite integrals over free and stratified surfaces are derived.展开更多
We use Radial Basis Functions （RBFs） to reconstruct smooth surfaces from 3D scattered data. An object＇s surface is defined implicitly as the zero set of an RBF fitted to the given surface data. We propose improveme...We use Radial Basis Functions （RBFs） to reconstruct smooth surfaces from 3D scattered data. An object＇s surface is defined implicitly as the zero set of an RBF fitted to the given surface data. We propose improvements on the methods of surface reconstruction with radial basis functions. A sparse approximation set of scattered data is constructed by reducing the number of interpolating points on the surface. We present an adaptive method for finding the off-surface normal points. The order of the equation decreases greatly as the number of the off-surface constraints reduces gradually. Experimental results are provided to illustrate that the proposed method is robust and may draw beautiful graphics.展开更多
The mass mortality of pond-reared scattered mirror carp, Cyprinus carpio, caused by Thelohanellus kitauei, occurred at fish farms in Sichuan Province, southwest China. Morphological and molecular analyses were supplem...The mass mortality of pond-reared scattered mirror carp, Cyprinus carpio, caused by Thelohanellus kitauei, occurred at fish farms in Sichuan Province, southwest China. Morphological and molecular analyses were supplemented with histological evaluation of infected tissues to better understand the route of infection and the pathological effects of 1＂. kitauei on the fish host. The intestine of the diseased host was full of large cysts of the myxosporean. The cysts range from 2 cm to 3.6 cm in diameter. Histopathology indicated that T. kitauei first invaded the submucosa of the host intestine and then moved into the mucosa layers with the development of their spores, finally entering into the enteric cavity of the hosts after the disruption of mucosa layers. The pyriform spores of T. kitauei were surrounded by the transparent spore sheath, measuring 25.98/μm±0.95 μm in body length, 8.72 μm±0.51μm body width, and 7.86 μm±0.26 μm in body thickness. The single polar capsule was pyriform, measuring 14.73 μm±0.92μm in length and 6.82 μm±0.45μm in width, with eight to 10 turns of filament coils winding inside. Phylogenetic analysis based on the 18S small-subunit ribosomal DNA sequences indicated that minimal genetic differences were present between T. kitauei samples from South Korea and from China. Close affinity was found between the genus Thelohanellus and Myxobolus. Additionally, two polar capsule nuclei were found at the anterior end of the single polar capsule in spores of T. kitauei stained with hematoxylin and eosin, which suggested the separation of the genus Thelohanellus from Myxobolus.展开更多
From July 31 to August I in 2008, a strong thunderstorm process occurred in Neijiang of Sichuan Province, and a strange scattered light- ning strike phenomenon happened in office building of Dongxing Meteorological Bu...From July 31 to August I in 2008, a strong thunderstorm process occurred in Neijiang of Sichuan Province, and a strange scattered light- ning strike phenomenon happened in office building of Dongxing Meteorological Bureau in Neijiang. Through a series of investigations and analyses, we found occurrence reason of the scattered lightning strike and improved lightning protection measures.展开更多
Scattering of the electromagnetic waves by a randomly inhomogeneous electrically gyrotropic slab are studied using the perturbation method. Second order statistical moments of the ordinary and extraordinary waves scat...Scattering of the electromagnetic waves by a randomly inhomogeneous electrically gyrotropic slab are studied using the perturbation method. Second order statistical moments of the ordinary and extraordinary waves scattered by the magnetized plasma slab are obtained using the boundary conditions for an arbitrary correlation function of electron density fluctuations. Normalized correlation functions at quasi-longitudinal propagation along the external magnetic field are calculated for the carrier frequency 0.1 MHz and 40 MHz. Isolines of the normalized variance of Faraday angle are constructed for the anisotropic Gaussian correlation function at various anisotropy factors of irregularities. Obtained results are in a good agreement with the experimental data.展开更多
基金Supported by the Ministry of Science and Higher Education of the Russian Federation as a part of World-class Research Center Program:Advanced Digital Technologies(contract No.075-15-2022-312 dated 20 April 2022).
文摘This study proposes a numerically efficient technique for computing the far-field scattered by a spherical target placed near the seabed.The bottom is supposed to be a homogeneous liquid attenuating half-space.The transmitter and receiver are situated at different points of a homogeneous water half-space.The distances between the transmitter,receiver,and object of interest are assumed to be much larger than the acoustic wavelength in water.The scattered far-field is ascertained using Hackman and Sammelmann’s general approach.The arising scattering coefficients of a sphere are assessed using the steepest descent approach.The branch cut contribution is also considered.The obtained formulas for the form-function can be used for acoustically rigid or soft scatterers,as well as elastic targets or spherical elastic shells.Numerical simulations are conducted for an acoustically rigid sphere.Asymptotic expressions for the scattering coefficients allow a decrease in the number of summands in the formula for the target strength and a significant reduction in computational time.
基金supported by Scientific Research and Technology Development Project of CNPC(2024ZG38,2024ZG42)the CNPC Innovation Fund(2022DQ02-0307).
文摘Fractures play a crucial role in various fields such as hydrocarbon exploration,groundwater resources management,and earthquake research.The determination of fracture location and the estimation of parameters such as fracture length and dip angle are the focus of geophysical work.In borehole observation system,the short distance between fractures and detectors leads to weak attenuation of elastic wave energy,and high-frequency source makes it easier to identify small-scale fractures.Compared to traditional monopole logging methods,dipole logging method has advantage of exciting pure shear waves sensitive to fractures,so its application is becoming increasingly widespread.However,since the reflected shear waves and scattered shear waves of fractures correspond to different fracture properties,how to distinguish and analyze these two kinds of waves is crucial for accurately characterizing the fracture parameters.To address this issue,numerical simulation of wave responses by a single fracture near a borehole in rock formation is performed,and the generation mechanism and characteristics of shear waves scattered by fractures are investigated.It is found that when the dip angle of the fracture surpasses a critical threshold,the S-wave will propagate to both endpoints of the fracture and generate scattered S-waves,resulting in two distinct scattered wave packets on the received waveform.When the polarization direction of the acoustic source is parallel to the strike of the fracture,the scattered SH-waves always have larger amplitude than the scattered SV-waves regardless of changing the fracture dip angle.Unlike SV-waves,the SH-waves scattered by the fracture do not have any mode conversion.Additionally,propagation of S-waves to a short length fracture can induce dipole mode vibration of the fracture within a wide frequency range.The phenomena of shear waves reflected and scattered by the fracture are further illustrated and verified by two field examples,thus showing the potential of scattered waves for fracture evaluation and characterization with borehole observation system.
基金Project supported by the National Natural Science Foundation of China(Grant No.12074261)the Natural Science Foundation of Shanghai(Grant No.20ZR1441600)。
文摘By employing a full quantum theory of electron-photon scattering in intense laser fields,we calculate the angularresolved radiation rate of the fundamental wave in Thomson scattering.We investigate the dependence of radiation rate on Euler angles and elucidate the underlying physical mechanism.The figure-8 profile of the radiation rate within the polarization plane is validated,while its evolution with respect to laser intensity and electron momentum is illustrated.Our findings reveal that in lower-intensity laser fields and for slow electron motion,the angular-resolved radiation rate exhibits distinct dipole emission characteristics.However,significant changes are observed at high laser intensities and/or large electron momenta,leading to pronounced alterations in the angular-resolved radiation rate.Remarkably similar variation patterns can be achieved by proportionally adjusting both laser intensity and electron momentum.
基金supported by the Government of the Russian Federation grant number 075-15-2025-009 of 28 February 2025 and by the Russian Science Foundation,Grant No.24-72-10127.
文摘During daylight laser polarization sensing of high-level clouds(HLCs),the lidar receiving system generates a signal caused by not only backscattered laser radiation,but also scattered solar radiation,the intensity and polarization of which depends on the Sun’s location.If a cloud contains spatially oriented ice particles,then it becomes anisotropic,that is,the coefficients of directional light scattering of such a cloud depend on the Sun’s zenith and azimuth angles.In this work,the possibility of using the effect of anisotropic scattering of solar radiation on the predictive ability of machine learning algorithms in solving the problem of predicting the HLC backscattering phase matrix(BSPM)was evaluated.The hypothesis that solar radiation scattered on HLCs has no effect on the BSPM elements of such clouds determined with a polarization lidar was tested.The operation of two algorithms for predicting the BSPM elements is evaluated.To train the first one,meteorological data were used as input parameters;for the second algorithm,the azi-muthal and zenith angles of the Sun’s position were added to the meteorological parameters.It is shown that there is no significant improvement in the predictive ability of the algorithm.
基金supported financially by the National Key Project(Grant No.2008ZX05035)the 973 Program(Grant No. 2009CB219603 and 2007CB209406)the National Natural Science Foundation of China(Grant No.50974081)
文摘Conventional seismic exploration,mostly based on reflection theory,hardly has accurate imaging results for disaster geologic bodies which have small scale,steep dip,or complex structure.In this paper,we design two typical geologic models for analyzing the characteristics of scattered waves in mines for forward modeling by finite difference and apply the equivalent offset migration（EOM）and EOM-based interference stack migration methods to mine prospecting.We focus on the analysis of scatted imaging’s technological superiority to reflection imaging.Research shows：1）scattered imaging can improve fold and make the best of weak scattered information,so it shows better results than post-stack migration imaging and 2）it can utilize the diffraction stack migration method-based ray path theory for mine seismic advanced prediction,so it provides an new efficient imaging method for improving resolution of mine seismic exploration.
基金partly supported by the Public Geological Survey Project(No.201011039)the National High Technology Research and Development Project of China(No.2007AA06Z134)the 111 Project under the Ministry of Education and the State Administration of Foreign Experts Affairs,China(No.B07011)
文摘This paper presents a reasonable gridding-parameters extraction method for setting the optimal interpolation nodes in the gridding of scattered observed data. The method can extract optimized gridding parameters based on the distribution of features in raw data. Modeling analysis proves that distortion caused by gridding can be greatly reduced when using such parameters. We also present some improved technical measures that use human- machine interaction and multi-thread parallel technology to solve inadequacies in traditional gridding software. On the basis of these methods, we have developed software that can be used to grid scattered data using a graphic interface. Finally, a comparison of different gridding parameters on field magnetic data from Ji Lin Province, North China demonstrates the superiority of the proposed method in eliminating the distortions and enhancing gridding efficiency.
基金Supported by National Key R&D Program of China(Grant No.2016YFF0203000)State Key Program of National Natural Science Foundation of China(Grant No.11834008)+5 种基金National Natural Science Foundation of China(Grant Nos.11774167,61571222)Fundamental research funds for the Central Universities(Grant No.020414380001)State Key Laboratory of Acoustics,Chinese Academy of Science(Grant No.SKLA201809)Key Laboratory of Underwater Acoustic Environment,Chinese Academy of Sciences(Grant No.SSHJ-KFKT-1701)AQSIQ technology R&D program(Grant No.2017QK125)Innovative Talents Program of Far East NDT New Technology&Application Forum
文摘The scattered fields of plane waves in a solid from a cylinder or sphere are critical in determining its acoustic characteristics as well as in engineering applications. This paper investigates the scattered field distributions of different incident waves created by elastic cylinders embedded in an elastic isotropic medium. Scattered waves, including longitudinal and transverse waves both inside and outside the cylinder, are described with specific modalities under an incident plane wave. A model with a scatterer embedded in a structural steel matrix and filled with aluminum is developed for comparison with the theoretical solution. The frequency of the plane wave ranged from 235 kHz to 2348 kHz, which corresponds to scaling factors from 0.5 to 5. Scattered field distributions in matrix materials blocked by an elastic cylindrical solid have been obtained by simulation or calculated using existing parameters. The simulation results are in good agreement with the theoretical solution, which supports the correctness of the simulation analysis. Furthermore, ultrasonic phased arrays are used to study scattered fields by changing the characteristics of the incident wave. On this foundation, a partial preliminary study of the scattered field distribution of double cylinders in a solid has been carried out, and the scattered field distribution at a given distance has been found to exhibit particular behaviors at different moments. Further studies on directivities and scattered fields are expected to improve the quantification of scattered images in isotropic solid materials by the phased array technique.
基金Project supported by the National Natural Science Foundation of China(Grant No.61178089)the Key Program of Science and Technology of Fujian Province,China(Grant No.2011Y0019)the Educational Department of Fujian Province,China(Grant No.JA13074)
文摘An analytic equation interpreting the intensity of ultrasound-modulated scattering light is derived, based on diffusion theory and previous explanations of the intensity modulation mechanism. Furthermore, an experiment of ultrasonic modulation of incoherent light in a scattering medium is developed. This analytical model agrees well with experimental results,which confirms the validity of the proposed intensity modulation mechanism. The model supplements the existing research on the ultrasonic modulation mechanism of scattering light.
基金the Western China Program for Personnel Training of Chinese Academy of Sciences (L10416004)National Social Science Foundation of China (06BJY076)Knowledge Innovation Project Chinese Academy of Sciences
文摘Making rural settlements of Mountainous Regions in Western Sichuan as the study objects and using symbolic statistical methods, then combining the case study of Daofu County, the paper analyzes the negative impact of the scattered rural settlements on infrastructure construction, farmers＇ income increase and mountain ecological reconstruction in mountainous regions of western Sichuan. The results indicate that economic density is positively related to both rural settlements density （R^2=0.73） and rural population density （R^2=0.77）, and it is the same for relationship between towns density and rural settlements density （R^2=0.88） and between towns density and economic density （R^2=0.71）, and the scattered distribution pattern of the rural settlements and shortage of economic centers is a major factor to the lagged socioeconomic development. On the eco-economic zoning to Daofu County, the paper indicates the spatial distribution model and the industrial development model of the rural settlements need to be changed, and rural population should be concentrated in larger rural settlements with development of off-farm industries while infrastructure construction is to reinforced.
基金Supported by the National Natural Science Foundation of China under Grant No.10045001.
文摘A new detection system in scanning electron microscope,which filters in energy and detects the backscattered electrons close to the microscope axis,is described.This technique ameliorates the dependence of the back.scat tering coefficient on atomic number,and suppresses effectively the relief contrast at the same time.Therefore this new method is very suitable to the composition analysis.
文摘Scattered storage means an item can be stored in multiple inventory bins. The scattered storage assignment problem based on association rules in Kiva mobile fulfillment system is investigated, which aims to decide the pods for each item to put on so as to minimize the number of pods to be moved when picking a batch of orders. This problem is formulated into an integer programming model. A genetic algorithm is developed to solve the large-sized problems. Computational experiments and comparison between the scattered storage strategy and random storage strategy are conducted to evaluate the performance of the model and algorithm.
基金Supported by the Special Funds Tianyuan for the National Natural Science Foundation of China(Grant No.11426086)the Fundamental Research Funds for the Central Universities(Grant No.2016B08714)the Natural Science Foundation of Jiangsu Province for the Youth(Grant No.BK20160853)
文摘In the paper, firstly, based on new non-tensor-product-typed partially inverse divided differences algorithms in a recursive form, scattered data interpolating schemes are constructed via bivariate continued fractions with odd and even nodes, respectively. And equivalent identities are also obtained between interpolated functions and bivariate continued fractions. Secondly, by means of three-term recurrence relations for continued fractions, the characterization theorem is presented to study on the degrees of the numerators and denominators of the interpolating continued fractions. Thirdly, some numerical examples show it feasible for the novel recursive schemes. Meanwhile, compared with the degrees of the numera- tors and denominators of bivariate Thiele-typed interpolating continued fractions, those of the new bivariate interpolating continued fractions are much low, respectively, due to the reduc- tion of redundant interpolating nodes. Finally, the operation count for the rational function interpolation is smaller than that for radial basis function interpolation.
基金supported by the National Natural Science Foundation of China(No.61404362)。
文摘Aiming at the problem of underwater polarized laser scattering caused by underwater suspended particles, the equivalent spherical particle Mie scattering theory simulation method is used to study the polarization characteristics of underwater scattered light. The relationship between underwater suspended particle characteristics and optical characteristics is analyzed, and the effects of particle size, polarization characteristics of incident light, and angle of incidence on the degree of polarization of forward and backward scattering light are studied. The results show that: When the incident light is natural light, the degree of polarization of scattered light is very low at the forward-scattering angle, which increases with the increase of the scattering angle, but changes frequently with the increase of the particle size. When the incident light is linearly polarized, the degree of linear polarization of the scattered light is related to the azimuth Angle. The degree of circular polarization is largely unaffected by particle size.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 61172031 and 41175012)
文摘The maritime tropospheric duct is a low-altitude anomalous refractivity structure over the ocean surface,and it can significantly affect the performance of many shore-based/shipboard radar and communication systems.We propose the idea that maritime tropospheric ducts can be retrieved from ocean forward-scattered low-elevation global positioning system（GPS） signals.Retrieval is accomplished by matching the measured power patterns of the signals to those predicted by the forward propagation model as a function of the modified refractivity profile.On the basis of a parabolic equation method and bistatic radar equation,we develop such a forward model for computing the trapped propagation characteristics of an ocean forward-scattered GPS signal within a tropospheric duct.A new GPS scattering initial field is defined for this model to start the propagation modeling.A preliminary test on the performance of this model is conducted using measured data obtained from a 2009-experiment in the South China Sea.Results demonstrate that this model can predict GPS propagation characteristics within maritime tropospheric ducts and serve as a forward model for duct inversion.
基金National Natural Science Foundation of China (19802023)
文摘By using the theories on Stokes multicolored water waves and taking the two- layer ocean as a basic model of stratified ocean, the paper analyzes the problems related to the effects of the nonlinear water wave on offshore structures. A mathematical expression is presented to describe second order wave radiation conditions. Using integral principle, the analytical integral solutions are given to evaluate second order scattered wave loads on general vertical circular cylinders in the two-layer ocean, and the special recurrence formulas for infinite integrals over free and stratified surfaces are derived.
文摘We use Radial Basis Functions （RBFs） to reconstruct smooth surfaces from 3D scattered data. An object＇s surface is defined implicitly as the zero set of an RBF fitted to the given surface data. We propose improvements on the methods of surface reconstruction with radial basis functions. A sparse approximation set of scattered data is constructed by reducing the number of interpolating points on the surface. We present an adaptive method for finding the off-surface normal points. The order of the equation decreases greatly as the number of the off-surface constraints reduces gradually. Experimental results are provided to illustrate that the proposed method is robust and may draw beautiful graphics.
基金Supported by the earmarked fund for China Agriculture Research System(No.CARS-46-08)the National Science Foundation for Young Scientists of China(No.31301863)the Major Scientific and Technological Innovation Project of Hubei Province(No.2015ABA045)
文摘The mass mortality of pond-reared scattered mirror carp, Cyprinus carpio, caused by Thelohanellus kitauei, occurred at fish farms in Sichuan Province, southwest China. Morphological and molecular analyses were supplemented with histological evaluation of infected tissues to better understand the route of infection and the pathological effects of 1＂. kitauei on the fish host. The intestine of the diseased host was full of large cysts of the myxosporean. The cysts range from 2 cm to 3.6 cm in diameter. Histopathology indicated that T. kitauei first invaded the submucosa of the host intestine and then moved into the mucosa layers with the development of their spores, finally entering into the enteric cavity of the hosts after the disruption of mucosa layers. The pyriform spores of T. kitauei were surrounded by the transparent spore sheath, measuring 25.98/μm±0.95 μm in body length, 8.72 μm±0.51μm body width, and 7.86 μm±0.26 μm in body thickness. The single polar capsule was pyriform, measuring 14.73 μm±0.92μm in length and 6.82 μm±0.45μm in width, with eight to 10 turns of filament coils winding inside. Phylogenetic analysis based on the 18S small-subunit ribosomal DNA sequences indicated that minimal genetic differences were present between T. kitauei samples from South Korea and from China. Close affinity was found between the genus Thelohanellus and Myxobolus. Additionally, two polar capsule nuclei were found at the anterior end of the single polar capsule in spores of T. kitauei stained with hematoxylin and eosin, which suggested the separation of the genus Thelohanellus from Myxobolus.
文摘From July 31 to August I in 2008, a strong thunderstorm process occurred in Neijiang of Sichuan Province, and a strange scattered light- ning strike phenomenon happened in office building of Dongxing Meteorological Bureau in Neijiang. Through a series of investigations and analyses, we found occurrence reason of the scattered lightning strike and improved lightning protection measures.
文摘Scattering of the electromagnetic waves by a randomly inhomogeneous electrically gyrotropic slab are studied using the perturbation method. Second order statistical moments of the ordinary and extraordinary waves scattered by the magnetized plasma slab are obtained using the boundary conditions for an arbitrary correlation function of electron density fluctuations. Normalized correlation functions at quasi-longitudinal propagation along the external magnetic field are calculated for the carrier frequency 0.1 MHz and 40 MHz. Isolines of the normalized variance of Faraday angle are constructed for the anisotropic Gaussian correlation function at various anisotropy factors of irregularities. Obtained results are in a good agreement with the experimental data.
