In this study, precision agriculture management zones were delineated using yield data over four years from the combine harvester equipped with yield monitor and DGPS receiver. Relative yields measured during each yea...In this study, precision agriculture management zones were delineated using yield data over four years from the combine harvester equipped with yield monitor and DGPS receiver. Relative yields measured during each year were interpolated to 4 m2 grid size using ordinary kriging. The resultant interpolated yield maps were averaged across years to create a map of the mean relative yield, which was then used for cluster analysis. The mean yield map of post-classification was processed by applying majority filtering with window sizes that were equivalent to the grid sizes of 12, 20, 28, 36, 44, 52 and 60 m. The scale effect of management zones was evaluated using relative variance reduction, test of significant differences of the means of yield zones, spatial fragmentation, and spatial agreement. The results showed that the post-classification majority filtering (PCMF) eliminated lots of isolated cells or patches caused by random variation while preserving yield means, high variance reduction, general yield patterns, and high spatial agreement. The zoned result can be used as yield goal map for preplant or in-season fertilizer recommendation in precision agriculture.展开更多
The Qilian Orogen Zone(QOZ), located in the north margin of the Tibetan Plateau, is the key area for understanding the deformation and dynamics process of Tibet. Numerous geological and geophysical studies have been c...The Qilian Orogen Zone(QOZ), located in the north margin of the Tibetan Plateau, is the key area for understanding the deformation and dynamics process of Tibet. Numerous geological and geophysical studies have been carried out on the mechanics of the Tibetan Plateau deformation and uplift; however, the detailed structure and deformation style of the Qilian Orogen Zone have remained uncertain due to poor geophysical data coverage and limited resolution power of inversion algorithms. In this study, we analyze the P-wave velocity structure beneath the Qilian Orogen Zone, obtained by applying multi-scale seismic tomography technique to P-wave arrival time data recorded by regional seismic networks. The seismic tomography algorithm used in this study employs sparsity constraints on the wavelet representation of the velocity model via L1-norm regularization. This algorithm can deal efficiently with uneven-sampled volumes, and can obtain multi-scale images of the velocity model. Our results can be summarized as follows:(1) The crustal velocity structure is strongly inhomogeneous and consistent with the surface geological setting. Significant low-velocity anomalies exist in the crust of northeastern Tibet, and slight high-velocity anomalies exist beneath the Qaidam Basin and Alxa terrane.(2)The Qilian Orogen Zone can be divided into two main parts by the Laji Shan Faults: the northwestern part with a low-velocity feature, and the southeastern part with a high-velocity feature at the upper and middle crust.(3) Our tomographic images suggest that northwestern and southeastern Qilian Orogen Zones have undergone different tectonic processes. In the northwest Qilian Orogen Zone, the deformation and growth of the Northern Tibetan Plateau has extended to the Heli Shan and Beida Shan region by northward overthrusting at the upper crust and thickening in the lower crust. We speculate that in the southeast Qilian Orogen Zone the deformation and growth of the Northern Tibet Plateau were of strike-slip style at the upper crust; in the lower crust, the evidence suggests ductile shear extrusion style and active frontage extension to the Alxa terrane.(4) The multi-scale seismic tomography technique provides multiscale analysis and sparse constraints, which has allowed to us obtain stable, high-resolution results.展开更多
High-pressure(HP)veins were extensively developed in western Tianshan high-pressure(HP)metamorphic belt.The HP vein and host-rocks were analyzed by electronic microprobe to trace the origin of vein-forming fluids.Anal...High-pressure(HP)veins were extensively developed in western Tianshan high-pressure(HP)metamorphic belt.The HP vein and host-rocks were analyzed by electronic microprobe to trace the origin of vein-forming fluids.Analytical data show that the immediately adjacent host-rocks of the studied HP vein are eclogites and gradually turned into blueschist as the distance from the veins increases,which indicates that the vein-forming fluid was derived from adjacent host-rocks;the boundaries between the vein and the host-rocks are sharp,which indicates that the fracture of the host-rocks is brittle during the vein-forming process.It is suggested that this type of HP veins is precipitated from the liquid formed by the dehydration of the host-rocks during the prograde metamorphism from blueschist to eclogite facies,which results in hydrofracturing of the rocks and provides the space for the vein to precipitate.The width of the eclogite-facies host-rocks is usually 1-2 cm,which provides the direct evidence that the fluid flow is on centimeter-scale.展开更多
The main aim of this research is to get a better knowledge and understanding of the micro-scale oscillatory networks behavior in the solid propellants reactionary zones. Fundamental understanding of the micro-and nano...The main aim of this research is to get a better knowledge and understanding of the micro-scale oscillatory networks behavior in the solid propellants reactionary zones. Fundamental understanding of the micro-and nano-scale combustion mechanisms is essential to the development and further improvement of the next-generation technologies for extreme control of the solid propellant thrust. Both experiments and theory confirm that the micro-and nano-scale oscillatory networks excitation in the solid propellants reactionary zones is a rather universal phenomenon. In accordance with our concept,the micro-and nano-scale structures form both the fractal and self-organized wave patterns in the solid propellants reactionary zones. Control by the shape, the sizes and spacial orientation of the wave patterns allows manipulate by the energy exchange and release in the reactionary zones. A novel strategy for enhanced extreme thrust control in solid propulsion systems are based on manipulation by selforganization of the micro-and nano-scale oscillatory networks and self-organized patterns formation in the reactionary zones with use of the system of acoustic waves and electro-magnetic fields, generated by special kind of ring-shaped electric discharges along with resonance laser radiation. Application of special kind of the ring-shaped electric discharges demands the minimum expenses of energy and opens prospects for almost inertia-free control by combustion processes. Nano-sized additives will enhance self-organizing and self-synchronization of the micro-and nano-scale oscillatory networks on the nanometer scale. Suggested novel strategy opens the door for completely new ways for enhanced extreme thrust control of the solid propulsion systems.展开更多
In this paper, the large eddy simulation method is used combined with the marker and cell method to study the wave propagation or shoaling and breaking process. As wave propagates into shallow water, the shoaling lead...In this paper, the large eddy simulation method is used combined with the marker and cell method to study the wave propagation or shoaling and breaking process. As wave propagates into shallow water, the shoaling leads to the increase of wave height, and then at a certain position, the wave will be breaking. The breaking wave is a powerful agent for generating turbulence, which plays an important role in most of the fluid dynamic processes throughout the sarf zone, such as transformation of wave energy, generation of near-shore current and diffusion of materials. So a proper numerical model for describing the turbulence effect is needed. In this paper, a revised Smagorinsky subgrid-scale model is used to describe the turbulence effect. The present study reveals that the coefficient of the Smagorinsky model for wave propagation or breaking simulation may be taken as a varying function of the water depth and distance away from the wave breaking point. The large eddy simulation model presented in this paper has been used to study the propagation of the solitary wave in constant water depth and the shoaling of the non-breaking solitary wave on a beach. The model is based on large eddy simulation, and to track free-surface movements, the Tokyo University Modified Marker and Cell (TUMMAC) method is employed. In order to ensure the accuracy of each component of this wave mathematical model,several steps have been taken to verify calculated solutions with either analytical solutions or experimental data. For non-breaking waves, very accurate results are obtained for a solitary wave propagating over a constant depth and on a beach. Application of the model to cnoidal wave breaking in the surf zone shows that the model results are in good agreement with analytical solution and experimental data. From the present model results, it can be seen that the turbulent eddy viscosity increases from the bottom to the water surface in surf zone. In the eddy viscosity curve, there is a turn-point obviously, dividing water depth into two parts; in the upper part, the eddy viscosity becomes very large near the wave br eaking position.展开更多
Based on the latest displacement of Huoshan piedmont fault, Mianshan west-side fault and Taigu fault obtained from the beginning of 1990's up to the present, the characteristics of distribution and displacement of...Based on the latest displacement of Huoshan piedmont fault, Mianshan west-side fault and Taigu fault obtained from the beginning of 1990's up to the present, the characteristics of distribution and displacement of surface rupture zone of the 1303 Hongtong M = 8 earthquake, Shanxi Province are synthesized and discussed in the paper. If Taigu fault, Mianshan west-side fault and Huoshan piedmont fault were contemporarily active during the 1303 Hongtong M = 8 earthquake, the surface rupture zone would be 160 km long and could be divided into 3 segments, that is, the 50-km-long Huoshan piedmont fault segment, 35-km-long Mianshan west-side fault segment and 70-km-long Taigu fault segment, respectively. Among them, there exist 4 km and 8 km step regions. The surface rupture zone exhibits right-lateral features. The displacements of northern and central segments are respectively 6～7 m and the southern segment has the maximum displacement of 10 m. The single basin-boundary fault of Shanxi fault-depression system usually corresponds to M ≈ 7 earthquake, while this great earthquake (M = 8) broke through the obstacle between two basins. It shows that the surface rupture scale of great earthquake is changeable.展开更多
基金The study was funded by the National Natural Science Foundation of China （40471093, 40591118）Beijing Natural Science Foundation （4061002）.
文摘In this study, precision agriculture management zones were delineated using yield data over four years from the combine harvester equipped with yield monitor and DGPS receiver. Relative yields measured during each year were interpolated to 4 m2 grid size using ordinary kriging. The resultant interpolated yield maps were averaged across years to create a map of the mean relative yield, which was then used for cluster analysis. The mean yield map of post-classification was processed by applying majority filtering with window sizes that were equivalent to the grid sizes of 12, 20, 28, 36, 44, 52 and 60 m. The scale effect of management zones was evaluated using relative variance reduction, test of significant differences of the means of yield zones, spatial fragmentation, and spatial agreement. The results showed that the post-classification majority filtering (PCMF) eliminated lots of isolated cells or patches caused by random variation while preserving yield means, high variance reduction, general yield patterns, and high spatial agreement. The zoned result can be used as yield goal map for preplant or in-season fertilizer recommendation in precision agriculture.
基金supported by the National Natural Science Foundation of China(41574045,41590862)State Key Laboratory of Earthquake Dynamics(LED2013A06)
文摘The Qilian Orogen Zone(QOZ), located in the north margin of the Tibetan Plateau, is the key area for understanding the deformation and dynamics process of Tibet. Numerous geological and geophysical studies have been carried out on the mechanics of the Tibetan Plateau deformation and uplift; however, the detailed structure and deformation style of the Qilian Orogen Zone have remained uncertain due to poor geophysical data coverage and limited resolution power of inversion algorithms. In this study, we analyze the P-wave velocity structure beneath the Qilian Orogen Zone, obtained by applying multi-scale seismic tomography technique to P-wave arrival time data recorded by regional seismic networks. The seismic tomography algorithm used in this study employs sparsity constraints on the wavelet representation of the velocity model via L1-norm regularization. This algorithm can deal efficiently with uneven-sampled volumes, and can obtain multi-scale images of the velocity model. Our results can be summarized as follows:(1) The crustal velocity structure is strongly inhomogeneous and consistent with the surface geological setting. Significant low-velocity anomalies exist in the crust of northeastern Tibet, and slight high-velocity anomalies exist beneath the Qaidam Basin and Alxa terrane.(2)The Qilian Orogen Zone can be divided into two main parts by the Laji Shan Faults: the northwestern part with a low-velocity feature, and the southeastern part with a high-velocity feature at the upper and middle crust.(3) Our tomographic images suggest that northwestern and southeastern Qilian Orogen Zones have undergone different tectonic processes. In the northwest Qilian Orogen Zone, the deformation and growth of the Northern Tibetan Plateau has extended to the Heli Shan and Beida Shan region by northward overthrusting at the upper crust and thickening in the lower crust. We speculate that in the southeast Qilian Orogen Zone the deformation and growth of the Northern Tibet Plateau were of strike-slip style at the upper crust; in the lower crust, the evidence suggests ductile shear extrusion style and active frontage extension to the Alxa terrane.(4) The multi-scale seismic tomography technique provides multiscale analysis and sparse constraints, which has allowed to us obtain stable, high-resolution results.
基金Project(2001CB409803)supported by the Major State Basic Research Development Program of China
文摘High-pressure(HP)veins were extensively developed in western Tianshan high-pressure(HP)metamorphic belt.The HP vein and host-rocks were analyzed by electronic microprobe to trace the origin of vein-forming fluids.Analytical data show that the immediately adjacent host-rocks of the studied HP vein are eclogites and gradually turned into blueschist as the distance from the veins increases,which indicates that the vein-forming fluid was derived from adjacent host-rocks;the boundaries between the vein and the host-rocks are sharp,which indicates that the fracture of the host-rocks is brittle during the vein-forming process.It is suggested that this type of HP veins is precipitated from the liquid formed by the dehydration of the host-rocks during the prograde metamorphism from blueschist to eclogite facies,which results in hydrofracturing of the rocks and provides the space for the vein to precipitate.The width of the eclogite-facies host-rocks is usually 1-2 cm,which provides the direct evidence that the fluid flow is on centimeter-scale.
基金supported by the Western-Caucasus Research Center
文摘The main aim of this research is to get a better knowledge and understanding of the micro-scale oscillatory networks behavior in the solid propellants reactionary zones. Fundamental understanding of the micro-and nano-scale combustion mechanisms is essential to the development and further improvement of the next-generation technologies for extreme control of the solid propellant thrust. Both experiments and theory confirm that the micro-and nano-scale oscillatory networks excitation in the solid propellants reactionary zones is a rather universal phenomenon. In accordance with our concept,the micro-and nano-scale structures form both the fractal and self-organized wave patterns in the solid propellants reactionary zones. Control by the shape, the sizes and spacial orientation of the wave patterns allows manipulate by the energy exchange and release in the reactionary zones. A novel strategy for enhanced extreme thrust control in solid propulsion systems are based on manipulation by selforganization of the micro-and nano-scale oscillatory networks and self-organized patterns formation in the reactionary zones with use of the system of acoustic waves and electro-magnetic fields, generated by special kind of ring-shaped electric discharges along with resonance laser radiation. Application of special kind of the ring-shaped electric discharges demands the minimum expenses of energy and opens prospects for almost inertia-free control by combustion processes. Nano-sized additives will enhance self-organizing and self-synchronization of the micro-and nano-scale oscillatory networks on the nanometer scale. Suggested novel strategy opens the door for completely new ways for enhanced extreme thrust control of the solid propulsion systems.
基金This research project was supported by the National Natural Science Foundation of China and The Hong Kong Research Grants under contracts No. 59809006 and No. 59890200, also by the Science Foundation of Tianjin Municipality under contract No. 9837020
文摘In this paper, the large eddy simulation method is used combined with the marker and cell method to study the wave propagation or shoaling and breaking process. As wave propagates into shallow water, the shoaling leads to the increase of wave height, and then at a certain position, the wave will be breaking. The breaking wave is a powerful agent for generating turbulence, which plays an important role in most of the fluid dynamic processes throughout the sarf zone, such as transformation of wave energy, generation of near-shore current and diffusion of materials. So a proper numerical model for describing the turbulence effect is needed. In this paper, a revised Smagorinsky subgrid-scale model is used to describe the turbulence effect. The present study reveals that the coefficient of the Smagorinsky model for wave propagation or breaking simulation may be taken as a varying function of the water depth and distance away from the wave breaking point. The large eddy simulation model presented in this paper has been used to study the propagation of the solitary wave in constant water depth and the shoaling of the non-breaking solitary wave on a beach. The model is based on large eddy simulation, and to track free-surface movements, the Tokyo University Modified Marker and Cell (TUMMAC) method is employed. In order to ensure the accuracy of each component of this wave mathematical model,several steps have been taken to verify calculated solutions with either analytical solutions or experimental data. For non-breaking waves, very accurate results are obtained for a solitary wave propagating over a constant depth and on a beach. Application of the model to cnoidal wave breaking in the surf zone shows that the model results are in good agreement with analytical solution and experimental data. From the present model results, it can be seen that the turbulent eddy viscosity increases from the bottom to the water surface in surf zone. In the eddy viscosity curve, there is a turn-point obviously, dividing water depth into two parts; in the upper part, the eddy viscosity becomes very large near the wave br eaking position.
基金Joint Seismological Science Foundation of China (No. 201017).
文摘Based on the latest displacement of Huoshan piedmont fault, Mianshan west-side fault and Taigu fault obtained from the beginning of 1990's up to the present, the characteristics of distribution and displacement of surface rupture zone of the 1303 Hongtong M = 8 earthquake, Shanxi Province are synthesized and discussed in the paper. If Taigu fault, Mianshan west-side fault and Huoshan piedmont fault were contemporarily active during the 1303 Hongtong M = 8 earthquake, the surface rupture zone would be 160 km long and could be divided into 3 segments, that is, the 50-km-long Huoshan piedmont fault segment, 35-km-long Mianshan west-side fault segment and 70-km-long Taigu fault segment, respectively. Among them, there exist 4 km and 8 km step regions. The surface rupture zone exhibits right-lateral features. The displacements of northern and central segments are respectively 6～7 m and the southern segment has the maximum displacement of 10 m. The single basin-boundary fault of Shanxi fault-depression system usually corresponds to M ≈ 7 earthquake, while this great earthquake (M = 8) broke through the obstacle between two basins. It shows that the surface rupture scale of great earthquake is changeable.
