The cultivation and development of modern metropolitan areas with the aim of establishing new regional centers with competitive edge is a key objective for the new-type urbanization directions in China.The constructio...The cultivation and development of modern metropolitan areas with the aim of establishing new regional centers with competitive edge is a key objective for the new-type urbanization directions in China.The construction of the Lhasa Metropolitan Area is of great significance for the promotion of the South Asia Channel,the‘Belt and Road’initiative,the Bangladesh-China-India-Myanmar Economic Corridor,the Himalaya Economic Cooperation Zone,and for rapid development and long-term stability of the Qinghai-Tibet Plateau.This paper examines the scope of the Lhasa Metropolitan Area including Chengguanqu(Chengguan District),Doilungdeqen,Dagze,Lhunzhub,Damxung,Nyemo,Quxu,Maizhokunggar,Samzhubze Qu(Samzhubze District),Gyangze,Rinbung,Bainang,Nedong,Gonggar,and Zhanang using a spatial field energy model that combines nodality and accessibility indices and considers multiple indicators including traffic flow between cities.By combining factors such as the natural background,population agglomeration,the social economy,infrastructure construction,and the urban spatial structure of the Lhasa Metropolitan Area,it is proposed to build a bow-and-arrow-shaped urban system with‘one core,two centers,one axis,and two wings’along the valleys and the transportation trunk lines of the area.The study advocates the construction of a pure land industrial system comprising a green cultural and tourism-oriented plateau.展开更多
The Limu tin deposits located in the Nanling tin and tungsten-polymetallic ore belt are now facing resource depletion after decades of exploitation.Peripheral mineral exploration therefore has become an urgent task.Us...The Limu tin deposits located in the Nanling tin and tungsten-polymetallic ore belt are now facing resource depletion after decades of exploitation.Peripheral mineral exploration therefore has become an urgent task.Using mineral exploration around the Limu crisis mines as an example,we introduce a breakthrough method of how the three-field theory,i.e.,the material,energy and spatial fields,is applied to intensively studies areas,a history of years of mineral exploitation and complex ore-forming systems.Taking a cue from Limu regional metallogeny,we based our investigation on the metallogenic information from geology,geophysics,geochemistry and remote sensing.We conducted our study of the three-field integrated information system,associated with metallogenic prognoses from deposits,with assignments and calculations which correct and allocate synthetic metallogenic prognosis by relying on GIS.We submitted a synthetic metallogenic prognosis map of tin in Limu where we delineated three ore target areas.A breakthrough was achieved by finding about 4785 t of tin metal outside the Shiziling deposit,which has been confirmed by drilling.The successful application in Limu shows that this three-field theory is of scientific and practical importance and deserves to be extended to utilization.展开更多
Along with the coming of the low-carbon era, people have paid more and more attention to the natural environment and eco-tourism will embrace a huge development. From the perspectives of the market relationship of sup...Along with the coming of the low-carbon era, people have paid more and more attention to the natural environment and eco-tourism will embrace a huge development. From the perspectives of the market relationship of supply-demand in economics and of field competition in physics, this paper has discussed upon the present status of the spatial structure of eco-tourism, and analyzed the relationship between supply-demand and field, in order to clarify the direction for the balance between supply and demand in the field and to guide eco-tourism to the way of sustainable development.展开更多
We theoretically study the selection of the quantum path in high-order harmonics（HHG） and isolated attosecond pulse generation from a one-dimensional（1D） model of a H_2~＋ molecule in few-cycle inhomogeneous laser...We theoretically study the selection of the quantum path in high-order harmonics（HHG） and isolated attosecond pulse generation from a one-dimensional（1D） model of a H_2~＋ molecule in few-cycle inhomogeneous laser fields.We show that the inhomogeneity of the laser fields play an important role in the HHG process.The cutoff of the harmonics can be extended remarkably,and the harmonic spectrum becomes smooth and has fewer modulations.We investigate the time-frequency profile of the time-dependent dipole,which shows that the short quantum path is enhanced and the long quantum path disappears in spatially inhomogeneous fields.The semi-classical three-step model is also applied to illustrate the physical mechanism of HHG.The influence of driving field carrier-envelop phase（CEP） on HHG is also discussed.By superposing a series of properly selected harmonics,an isolated attosecond pulse（IAP） with duration 53 as can be obtained by a 15-fs,1600-nm laser pulse with the parameter ε = 0.0013（e is the parameter that determines the order of inhomogeneity of the laser field）.展开更多
The effect of multiple rescattering processes on the harmonic emission from He atom in a spatially inhomogeneous field is discussed by solving the one-dimensional time-dependent Schrtdinger equation and the classical ...The effect of multiple rescattering processes on the harmonic emission from He atom in a spatially inhomogeneous field is discussed by solving the one-dimensional time-dependent Schrtdinger equation and the classical equation of motion. By establishing the physical model of the harmonic emission in the inhomogeneous field, we discuss the related characters of the multiple rescatterings process in the harmonic generation process. It shows that the second rescattering rather than the first rescattering tends to determine the harmonic cutoff energy when the inhomogeneous parameter is larger than 0.0055. Additionally, with the classica/simulation, the underlying physical mechanism of the continuum-continuum harmonics is also revealed. Moreover, this work may provide new physical insight into the harmonic generation in an inhomogeneous field, and is beneficial to further extract the harnaonic emission from molecular systems.展开更多
Traffic is an indispensable prerequisite for a tourism system. The ＂four vertical and four horizontal＂ HSR network represents an important milestone of the ＂traffic revolution＂ in China. It will affect the spatial...Traffic is an indispensable prerequisite for a tourism system. The ＂four vertical and four horizontal＂ HSR network represents an important milestone of the ＂traffic revolution＂ in China. It will affect the spatial pattern of tourism accessibility in Chinese cities, thus substan- tially increasing their power to attract tourists and their radiation force. This paper examines the evolution and spatial characteristics of the power to attract tourism of cities linked by China＇s HSR network by measuring the influence of accessibility of 338 HSR-linked cities using GIS analysis. The results show the following. （1） The accessibility of Chinese cities is optimized by the HSR network, whose spatial pattern of accessibility exhibits an obvious traf- fic direction and causes a high-speed rail-corridor effect. （2） The spatial pattern of tourism field strength in Chinese cities exhibits the dual characteristics of multi-center annular diver- gence and dendritic diffusion. Dendritic diffusion is particularly more obvious along the HSR line. The change rate of urban tourism field strength forms a high-value corridor along the HSR line and exhibits a spatial pattern of decreasing area from the center to the outer limit along the HSR line. （3） The influence of the higher and highest tourism field strength areas along the HSR line is most significant, and the number of cities that distribute into these two types of tourism field strengths significantly increases： their area expands by more than 100% HSR enhances the tourism field strength value of regional central cities, and the radiation range of tourism attraction extends along the HSR line.展开更多
The horizontal-longitudinal correlation of acoustic field for the receiver near the bottom is analyzed by using nu-merical modeling.An approximate analytical solution of horizontal-longitudinal correlation coefficient...The horizontal-longitudinal correlation of acoustic field for the receiver near the bottom is analyzed by using nu-merical modeling.An approximate analytical solution of horizontal-longitudinal correlation coefficient is derived based on the ray method.Combining the characteristic of Lloyd's mirror interference pattern,the variability of acoustic field and its effect on horizontal-longitudinal spatial correlation are discussed.The theoretical pre-diction agrees well with the numerical results.Experimental results confirm the validity of analytical solution.Finally,the applicability of the analytical solution is summarized.The conclusion is beneficial for the design of bottom-moored array and the estimation of integral time for moving source localization.展开更多
This article describes three algorithms for distance field generation on triangulated model: brute force algorithm, single-threaded algorithm based on spatial partition and multi-threaded algorithm based on spatial pa...This article describes three algorithms for distance field generation on triangulated model: brute force algorithm, single-threaded algorithm based on spatial partition and multi-threaded algorithm based on spatial partition. Spatial partition algorithm use equidistant network divide the bounding box into equal-sized cubes, calculates the maximum and minimum distances between the sample point and each of the small cubes,taking the minimum value from the maximum distance as the minimum distance from the sample point to the model named d1, comparing d1 with the distance from sample point to every little cube's minimum distance d2, if d1 <d2, the sample point's distance to all triangles inside this cube are greater than d1, skip this cube, otherwise, calculated the distance from the point to all the triangles intersect with the cube, then alternative d1 with the minimum value, circulate all small cubes intersect with the model. Comparing the calculation results, it can be seen that the algorithm about the multi-threaded distance field relative to the other two algorithms in computational speed is greatly improved especially for complex models.展开更多
A new approach to detecting ocean eddies automatically from remote sensing imageries based on the ocean eddy＇s eigen-pattern in remote sensing imagery and ＂force field-based shape extracting method＂ is proposed. Fi...A new approach to detecting ocean eddies automatically from remote sensing imageries based on the ocean eddy＇s eigen-pattern in remote sensing imagery and ＂force field-based shape extracting method＂ is proposed. First, the analysis on extracting eddies＇ edges from remote sensing imagery using conventional edge detection arithmetic operators is performed and returns digitized vector edge data as a result. Second, attraction forces and fusion forces between edge curves were analyzed and calculated based on the vector eddy edges. Thirdly, the virtual significant spatial patterns of eddy were detected automatically using iterative repetition followed by optimized rule. Finally, the spatial form auto-detection of different types of ocean eddies was done using satellite images. The study verified that this is an effective way to identify and detect the ocean eddy with a complex form.展开更多
Target detection is always an important application in hyperspectral image processing field. In this paper, a spectral-spatial target detection algorithm for hyperspectral data is proposed.The spatial feature and spec...Target detection is always an important application in hyperspectral image processing field. In this paper, a spectral-spatial target detection algorithm for hyperspectral data is proposed.The spatial feature and spectral feature were unified based on the data filed theory and extracted by weighted manifold embedding. The novelties of the proposed method lie in two aspects. One is the way in which the spatial features and spectral features were fused as a new feature based on the data field theory, and the other is that local information was introduced to describe the decision boundary and explore the discriminative features for target detection. The extracted features based on data field modeling and manifold embedding techniques were considered for a target detection task.Three standard hyperspectral datasets were considered in the analysis. The effectiveness of the proposed target detection algorithm based on data field theory was proved by the higher detection rates with lower False Alarm Rates（FARs） with respect to those achieved by conventional hyperspectral target detectors.展开更多
The contents of soil microelements can affect the growth, yield and quality of tobacco, but it is not clear of the status quo of soil microelements in tobacco fields in Liupanshui city. In this study, soil samples of ...The contents of soil microelements can affect the growth, yield and quality of tobacco, but it is not clear of the status quo of soil microelements in tobacco fields in Liupanshui city. In this study, soil samples of the plough layers (0 - 20 cm) were collected from January to March in 2021 from 500 typical tobacco fields in Liupanshui City (100, 180 and 220 fields in Zhongshan, Shuicheng and Panzhou, respectively), the particle size composition, pH, the contents of organic matter (OM), available boron (B), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo) and zinc (Zn) were measured and discussed. the results show that the mean contents of B, Cu, Fe, Mn, Mo and Zn are 0.92, 2.55, 66.47, 47.26, 0.39 and 3.96 mg/kg, respectively, and among which, B, Cu and Zn are at the high grades while Fe, Mn and Mo are at the very-high grades. There are significant differences in B, Fe and Zn among the three regions, while Cu is significantly different between Zhongshan and Shuicheng, Mn is significantly different between Panzhou with Zhongshan and Shuicheng, and Mo is significantly different between Zhongshan and Panzhou. The proportions of fields deficient in microelements are relatively low, no field is Fe-deficient, and the fields deficient in Mo, B, Cu, Zn and Mn are only account for 10.40%, 9.40%, 7.40%, 2.80% and 2.00% of the total fields respectively. B-deficient fields (green and light green colors, the same below) are mainly scattered in the northwest of Zhongshan and in the north and south of Panzhou, Cu-deficient fields mainly in the middle of Shuicheng and Panzhou, Mn-deficient fields mainly in northern Zhongshan, central Shuicheng and north of Panzhou. Mo-deficient fields are mainly in the middle of Shuicheng and the middle and east of Panzhou, while Zn-deficient fields are mainly in the middle of Shuicheng and the middle and east of Panzhou. Altitude is negatively correlated with Mn (P < 0.05), pH is negatively correlated with B (P < 0.05), Fe and Mn (P < 0.01), and OM is positively correlated with Fe and Zn (P < 0.01). Sand is negatively correlated with B (P < 0.05), Mn and Mo (P < 0.01), but positively correlated with Zn (P < 0.01). Silt is positively correlated with Mo (P < 0.05);clay is positively correlated with B (P < 0.05) and Mn (P < 0.01), but negatively correlated with Zn (P < 0.01). In conclusion, most of the fields do not need to apply micro-fertilizers in Liupanshui, but the fields deficient in microelements should be considered to use the corresponding fertilizers.展开更多
Applying 3-dimension finite difference method, the distribution characteristics of horizontal field transfer functions for rectangular conductor have been computed, and the law of distribution for Re-part and Im-part ...Applying 3-dimension finite difference method, the distribution characteristics of horizontal field transfer functions for rectangular conductor have been computed, and the law of distribution for Re-part and Im-part has been given. The influences of source field period, the conductivity, the buried depth and the length of the conductor on the transfer functions were studied. The extrema of transfer functions appear at the center, the four corners and around the edges of conductor, and move with the edges. This feature demonstrates that around the edges are best places for transfer functions' observation.展开更多
Half-space Green's function due to a spatially harmonic line load has been expressed as a sum of the full-space Green's functions and a 2-D integral representation of the reflected waves by the free surface of...Half-space Green's function due to a spatially harmonic line load has been expressed as a sum of the full-space Green's functions and a 2-D integral representation of the reflected waves by the free surface of the half-space.By using the obtained half-space Green's function,an integral rep- resentation of the scattered waves by a cylindrical obstacle is then derived.Finally,by analyzing the far-zone behavior of the integrands of the integral representation.the far-field pattern of the scattered waves in a half-space obtained.展开更多
In this work,laser induced tungsten plasma has been investigated in the absence and presence of 0.6 T static transverse magnetic field at atmospheric pressure in air.The spectroscopic characterization of laser induced...In this work,laser induced tungsten plasma has been investigated in the absence and presence of 0.6 T static transverse magnetic field at atmospheric pressure in air.The spectroscopic characterization of laser induced tungsten plasma was experimentally studied using space-resolved emission spectroscopy.The atomic emission lines of tungsten showed a significant enhancement in the presence of a magnetic field,while the ionic emission lines of tungsten presented little change.Temporal variation of the optical emission lines of tungsten indicated that the atomic emission time in the presence of a magnetic field was longer than that in the absence of a magnetic field,while no significant changes occurred for the ionic emission time.The spatial resolution of optical emission lines of tungsten demonstrated that the spatial distribution of atoms and ions were separated.The influence of a magnetic field on the spatial distribution of atoms was remarkable,whereas the spatial distribution of ions was little influenced by the magnetic field.The different behaviors between ions and atoms with and without magnetic field in air were related to the various atomic processes especially the electrons and ions recombination process during the plasma expansion and cooling process.展开更多
To meet the high demand for reliability based design of slopes, we present in this paper a simplified HLRF(Hasofere Linde Rackwitze Fiessler) iterative algorithm for first-order reliability method(FORM). It is simply ...To meet the high demand for reliability based design of slopes, we present in this paper a simplified HLRF(Hasofere Linde Rackwitze Fiessler) iterative algorithm for first-order reliability method(FORM). It is simply formulated in x-space and requires neither transformation of correlated random variables nor optimization tools. The solution can be easily improved by iteratively adjusting the step length. The algorithm is particularly useful to practicing engineers for geotechnical reliability analysis where standalone(deterministic) numerical packages are used. Based on the proposed algorithm and through direct perturbation analysis of random variables, we conducted a case study of earth slope reliability with complete consideration of soil uncertainty and spatial variability.展开更多
基金Strategic Priority Research Program of the Chinese Academy of Sciences(XDA20040401)The Second Comprehensive Scientific Investigation and Research on the Tibetan Plateau(2019QZKK1005)。
文摘The cultivation and development of modern metropolitan areas with the aim of establishing new regional centers with competitive edge is a key objective for the new-type urbanization directions in China.The construction of the Lhasa Metropolitan Area is of great significance for the promotion of the South Asia Channel,the‘Belt and Road’initiative,the Bangladesh-China-India-Myanmar Economic Corridor,the Himalaya Economic Cooperation Zone,and for rapid development and long-term stability of the Qinghai-Tibet Plateau.This paper examines the scope of the Lhasa Metropolitan Area including Chengguanqu(Chengguan District),Doilungdeqen,Dagze,Lhunzhub,Damxung,Nyemo,Quxu,Maizhokunggar,Samzhubze Qu(Samzhubze District),Gyangze,Rinbung,Bainang,Nedong,Gonggar,and Zhanang using a spatial field energy model that combines nodality and accessibility indices and considers multiple indicators including traffic flow between cities.By combining factors such as the natural background,population agglomeration,the social economy,infrastructure construction,and the urban spatial structure of the Lhasa Metropolitan Area,it is proposed to build a bow-and-arrow-shaped urban system with‘one core,two centers,one axis,and two wings’along the valleys and the transportation trunk lines of the area.The study advocates the construction of a pure land industrial system comprising a green cultural and tourism-oriented plateau.
文摘The Limu tin deposits located in the Nanling tin and tungsten-polymetallic ore belt are now facing resource depletion after decades of exploitation.Peripheral mineral exploration therefore has become an urgent task.Using mineral exploration around the Limu crisis mines as an example,we introduce a breakthrough method of how the three-field theory,i.e.,the material,energy and spatial fields,is applied to intensively studies areas,a history of years of mineral exploitation and complex ore-forming systems.Taking a cue from Limu regional metallogeny,we based our investigation on the metallogenic information from geology,geophysics,geochemistry and remote sensing.We conducted our study of the three-field integrated information system,associated with metallogenic prognoses from deposits,with assignments and calculations which correct and allocate synthetic metallogenic prognosis by relying on GIS.We submitted a synthetic metallogenic prognosis map of tin in Limu where we delineated three ore target areas.A breakthrough was achieved by finding about 4785 t of tin metal outside the Shiziling deposit,which has been confirmed by drilling.The successful application in Limu shows that this three-field theory is of scientific and practical importance and deserves to be extended to utilization.
文摘Along with the coming of the low-carbon era, people have paid more and more attention to the natural environment and eco-tourism will embrace a huge development. From the perspectives of the market relationship of supply-demand in economics and of field competition in physics, this paper has discussed upon the present status of the spatial structure of eco-tourism, and analyzed the relationship between supply-demand and field, in order to clarify the direction for the balance between supply and demand in the field and to guide eco-tourism to the way of sustainable development.
基金supported by the National Natural Science Foundation of China(Grant Nos.11174108,11104108,and 11271158)
文摘We theoretically study the selection of the quantum path in high-order harmonics（HHG） and isolated attosecond pulse generation from a one-dimensional（1D） model of a H_2~＋ molecule in few-cycle inhomogeneous laser fields.We show that the inhomogeneity of the laser fields play an important role in the HHG process.The cutoff of the harmonics can be extended remarkably,and the harmonic spectrum becomes smooth and has fewer modulations.We investigate the time-frequency profile of the time-dependent dipole,which shows that the short quantum path is enhanced and the long quantum path disappears in spatially inhomogeneous fields.The semi-classical three-step model is also applied to illustrate the physical mechanism of HHG.The influence of driving field carrier-envelop phase（CEP） on HHG is also discussed.By superposing a series of properly selected harmonics,an isolated attosecond pulse（IAP） with duration 53 as can be obtained by a 15-fs,1600-nm laser pulse with the parameter ε = 0.0013（e is the parameter that determines the order of inhomogeneity of the laser field）.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11404204,11274215,and 11504221)the Natural Science Foundation for Young Scientists of Shanxi Province,China(Grant No.2015021023)+1 种基金Program for the Top Young Academic Leaders of Higher Learning Institutions of Shanxi Province,ChinaInnovation Project for Postgraduates of Shanxi Province,China(Grant No.2017BY085)
文摘The effect of multiple rescattering processes on the harmonic emission from He atom in a spatially inhomogeneous field is discussed by solving the one-dimensional time-dependent Schrtdinger equation and the classical equation of motion. By establishing the physical model of the harmonic emission in the inhomogeneous field, we discuss the related characters of the multiple rescatterings process in the harmonic generation process. It shows that the second rescattering rather than the first rescattering tends to determine the harmonic cutoff energy when the inhomogeneous parameter is larger than 0.0055. Additionally, with the classica/simulation, the underlying physical mechanism of the continuum-continuum harmonics is also revealed. Moreover, this work may provide new physical insight into the harmonic generation in an inhomogeneous field, and is beneficial to further extract the harnaonic emission from molecular systems.
基金Foundation： National Natural Science Foundation of China, No. 41271134
文摘Traffic is an indispensable prerequisite for a tourism system. The ＂four vertical and four horizontal＂ HSR network represents an important milestone of the ＂traffic revolution＂ in China. It will affect the spatial pattern of tourism accessibility in Chinese cities, thus substan- tially increasing their power to attract tourists and their radiation force. This paper examines the evolution and spatial characteristics of the power to attract tourism of cities linked by China＇s HSR network by measuring the influence of accessibility of 338 HSR-linked cities using GIS analysis. The results show the following. （1） The accessibility of Chinese cities is optimized by the HSR network, whose spatial pattern of accessibility exhibits an obvious traf- fic direction and causes a high-speed rail-corridor effect. （2） The spatial pattern of tourism field strength in Chinese cities exhibits the dual characteristics of multi-center annular diver- gence and dendritic diffusion. Dendritic diffusion is particularly more obvious along the HSR line. The change rate of urban tourism field strength forms a high-value corridor along the HSR line and exhibits a spatial pattern of decreasing area from the center to the outer limit along the HSR line. （3） The influence of the higher and highest tourism field strength areas along the HSR line is most significant, and the number of cities that distribute into these two types of tourism field strengths significantly increases： their area expands by more than 100% HSR enhances the tourism field strength value of regional central cities, and the radiation range of tourism attraction extends along the HSR line.
基金Supported by the National Natural Science Foundation of China under Grant No 11174235
文摘The horizontal-longitudinal correlation of acoustic field for the receiver near the bottom is analyzed by using nu-merical modeling.An approximate analytical solution of horizontal-longitudinal correlation coefficient is derived based on the ray method.Combining the characteristic of Lloyd's mirror interference pattern,the variability of acoustic field and its effect on horizontal-longitudinal spatial correlation are discussed.The theoretical pre-diction agrees well with the numerical results.Experimental results confirm the validity of analytical solution.Finally,the applicability of the analytical solution is summarized.The conclusion is beneficial for the design of bottom-moored array and the estimation of integral time for moving source localization.
文摘This article describes three algorithms for distance field generation on triangulated model: brute force algorithm, single-threaded algorithm based on spatial partition and multi-threaded algorithm based on spatial partition. Spatial partition algorithm use equidistant network divide the bounding box into equal-sized cubes, calculates the maximum and minimum distances between the sample point and each of the small cubes,taking the minimum value from the maximum distance as the minimum distance from the sample point to the model named d1, comparing d1 with the distance from sample point to every little cube's minimum distance d2, if d1 <d2, the sample point's distance to all triangles inside this cube are greater than d1, skip this cube, otherwise, calculated the distance from the point to all the triangles intersect with the cube, then alternative d1 with the minimum value, circulate all small cubes intersect with the model. Comparing the calculation results, it can be seen that the algorithm about the multi-threaded distance field relative to the other two algorithms in computational speed is greatly improved especially for complex models.
文摘A new approach to detecting ocean eddies automatically from remote sensing imageries based on the ocean eddy＇s eigen-pattern in remote sensing imagery and ＂force field-based shape extracting method＂ is proposed. First, the analysis on extracting eddies＇ edges from remote sensing imagery using conventional edge detection arithmetic operators is performed and returns digitized vector edge data as a result. Second, attraction forces and fusion forces between edge curves were analyzed and calculated based on the vector eddy edges. Thirdly, the virtual significant spatial patterns of eddy were detected automatically using iterative repetition followed by optimized rule. Finally, the spatial form auto-detection of different types of ocean eddies was done using satellite images. The study verified that this is an effective way to identify and detect the ocean eddy with a complex form.
文摘Target detection is always an important application in hyperspectral image processing field. In this paper, a spectral-spatial target detection algorithm for hyperspectral data is proposed.The spatial feature and spectral feature were unified based on the data filed theory and extracted by weighted manifold embedding. The novelties of the proposed method lie in two aspects. One is the way in which the spatial features and spectral features were fused as a new feature based on the data field theory, and the other is that local information was introduced to describe the decision boundary and explore the discriminative features for target detection. The extracted features based on data field modeling and manifold embedding techniques were considered for a target detection task.Three standard hyperspectral datasets were considered in the analysis. The effectiveness of the proposed target detection algorithm based on data field theory was proved by the higher detection rates with lower False Alarm Rates（FARs） with respect to those achieved by conventional hyperspectral target detectors.
文摘The contents of soil microelements can affect the growth, yield and quality of tobacco, but it is not clear of the status quo of soil microelements in tobacco fields in Liupanshui city. In this study, soil samples of the plough layers (0 - 20 cm) were collected from January to March in 2021 from 500 typical tobacco fields in Liupanshui City (100, 180 and 220 fields in Zhongshan, Shuicheng and Panzhou, respectively), the particle size composition, pH, the contents of organic matter (OM), available boron (B), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo) and zinc (Zn) were measured and discussed. the results show that the mean contents of B, Cu, Fe, Mn, Mo and Zn are 0.92, 2.55, 66.47, 47.26, 0.39 and 3.96 mg/kg, respectively, and among which, B, Cu and Zn are at the high grades while Fe, Mn and Mo are at the very-high grades. There are significant differences in B, Fe and Zn among the three regions, while Cu is significantly different between Zhongshan and Shuicheng, Mn is significantly different between Panzhou with Zhongshan and Shuicheng, and Mo is significantly different between Zhongshan and Panzhou. The proportions of fields deficient in microelements are relatively low, no field is Fe-deficient, and the fields deficient in Mo, B, Cu, Zn and Mn are only account for 10.40%, 9.40%, 7.40%, 2.80% and 2.00% of the total fields respectively. B-deficient fields (green and light green colors, the same below) are mainly scattered in the northwest of Zhongshan and in the north and south of Panzhou, Cu-deficient fields mainly in the middle of Shuicheng and Panzhou, Mn-deficient fields mainly in northern Zhongshan, central Shuicheng and north of Panzhou. Mo-deficient fields are mainly in the middle of Shuicheng and the middle and east of Panzhou, while Zn-deficient fields are mainly in the middle of Shuicheng and the middle and east of Panzhou. Altitude is negatively correlated with Mn (P < 0.05), pH is negatively correlated with B (P < 0.05), Fe and Mn (P < 0.01), and OM is positively correlated with Fe and Zn (P < 0.01). Sand is negatively correlated with B (P < 0.05), Mn and Mo (P < 0.01), but positively correlated with Zn (P < 0.01). Silt is positively correlated with Mo (P < 0.05);clay is positively correlated with B (P < 0.05) and Mn (P < 0.01), but negatively correlated with Zn (P < 0.01). In conclusion, most of the fields do not need to apply micro-fertilizers in Liupanshui, but the fields deficient in microelements should be considered to use the corresponding fertilizers.
文摘Applying 3-dimension finite difference method, the distribution characteristics of horizontal field transfer functions for rectangular conductor have been computed, and the law of distribution for Re-part and Im-part has been given. The influences of source field period, the conductivity, the buried depth and the length of the conductor on the transfer functions were studied. The extrema of transfer functions appear at the center, the four corners and around the edges of conductor, and move with the edges. This feature demonstrates that around the edges are best places for transfer functions' observation.
文摘Half-space Green's function due to a spatially harmonic line load has been expressed as a sum of the full-space Green's functions and a 2-D integral representation of the reflected waves by the free surface of the half-space.By using the obtained half-space Green's function,an integral rep- resentation of the scattered waves by a cylindrical obstacle is then derived.Finally,by analyzing the far-zone behavior of the integrands of the integral representation.the far-field pattern of the scattered waves in a half-space obtained.
文摘In this work,laser induced tungsten plasma has been investigated in the absence and presence of 0.6 T static transverse magnetic field at atmospheric pressure in air.The spectroscopic characterization of laser induced tungsten plasma was experimentally studied using space-resolved emission spectroscopy.The atomic emission lines of tungsten showed a significant enhancement in the presence of a magnetic field,while the ionic emission lines of tungsten presented little change.Temporal variation of the optical emission lines of tungsten indicated that the atomic emission time in the presence of a magnetic field was longer than that in the absence of a magnetic field,while no significant changes occurred for the ionic emission time.The spatial resolution of optical emission lines of tungsten demonstrated that the spatial distribution of atoms and ions were separated.The influence of a magnetic field on the spatial distribution of atoms was remarkable,whereas the spatial distribution of ions was little influenced by the magnetic field.The different behaviors between ions and atoms with and without magnetic field in air were related to the various atomic processes especially the electrons and ions recombination process during the plasma expansion and cooling process.
基金Financial supports from National Science Foundation of China(Grant Nos.51609072,51879091,51479050 and 41630638)the National Key Basic Research Program of China("973" Program)(Grant No.2015CB057901)the Public Service Sector R&D Project of Ministry of Water Resource of China(Grant No.201501035-03)
文摘To meet the high demand for reliability based design of slopes, we present in this paper a simplified HLRF(Hasofere Linde Rackwitze Fiessler) iterative algorithm for first-order reliability method(FORM). It is simply formulated in x-space and requires neither transformation of correlated random variables nor optimization tools. The solution can be easily improved by iteratively adjusting the step length. The algorithm is particularly useful to practicing engineers for geotechnical reliability analysis where standalone(deterministic) numerical packages are used. Based on the proposed algorithm and through direct perturbation analysis of random variables, we conducted a case study of earth slope reliability with complete consideration of soil uncertainty and spatial variability.
