To improve the oxidation resistance and corrosion resistance of Zr-4 alloy, titanium nitride （TIN） coatings were prepared on the Zr-4 alloy with a TiN ceramic target with different ratios of N2. Microstructure and h...To improve the oxidation resistance and corrosion resistance of Zr-4 alloy, titanium nitride （TIN） coatings were prepared on the Zr-4 alloy with a TiN ceramic target with different ratios of N2. Microstructure and high-temperature properties of the TiN coated samples were studied by scanning electron microscopy （SEM）, energy dispersive spectrometer （EDS）, X-ray diffraction meter （XRD）, X-ray photoelectron spectroscopy （XPS）, heat treatment furnace and autoclaves, respectively. The x value of the TiN coatings （TiN） ranges from 0.96 to 1.33. After the introduction of N2, TiN coating exhibits a weak （200） plane and a preferred （111） orientation. The coating prepared with an N2 flow ratio of 15% shows an optimal oxidation resistance in the atmospheric environment at 800 ℃. In either 1 200 ℃ steam environment for one hour, or deionized water at 360 ℃ and a pressure of 18.6 Mpa for 16 d, the opitimized TiN coated samples have no delamination or spallation; and the gains in the masses of samples are much smaller than Zr-4 alloy. These results demonstrate the effectiveness of the optimized TiN coating as the protective coating on the Zr-4 alloy under extreme conditons.展开更多
annular beam tri-heterodyne confocal microscope has been proposed to improve the anti-environmental interference capability and the resolution of a eonfoeal microscope. It simultaneously detects far-, on-, and near-fo...annular beam tri-heterodyne confocal microscope has been proposed to improve the anti-environmental interference capability and the resolution of a eonfoeal microscope. It simultaneously detects far-, on-, and near-focus signals with given phase differences by dividing the measured light path of the eonfoeal microscope into three sub-paths （signals）. Pair-wise real-time heterodyne subtraction of the three signals is used to improve the anti-environmental interference capability, axial resolution, and linearity; and a shaped annular beam super-resolution technique is used to improve lateral resolution. Theoretical analyses and preliminary experiments indicate that an axial resolution of about 1 nm can be achieved with a shaped annular beam tri-heterodyne confoeal microscope and its lateral resolution can be better than 0.2 um for A = 632.8 nm, the numerical aperture of the lens of the microscope is NA = 0.85, and the normalized radius e = 0.5.展开更多
Acoustic vector sensor consists of pressure and particle velocity sensors,which measure the three-dimensional acoustic particle velocity,as well as the pressure at one location at the same time.By preserving the ampli...Acoustic vector sensor consists of pressure and particle velocity sensors,which measure the three-dimensional acoustic particle velocity,as well as the pressure at one location at the same time.By preserving the amplitude and phase information of the pressure and particle velocity,they possess a number of advantages over traditional scalar sensors.Signal-to-noise ratio (SNR) gain (which is often called array gain) is one of such advantages and is always interested by all of us.But it is not unchangeable if the spatial correlation of the noise field varies.Much more important,it is difficult to be given if the noise becomes complex.In this paper,spatial correlation of the vector field of isotropic volume-noise and surface-generated noise has been introduced briefly.Based on the results,the combined SNR output of a vector linear array is investigated and the maximum gain is given in the specified noise.Computer simulation shows that the output of one array in the same noise is not the same in different gestures.And then we find the best gesture through SNR calculation and obtain the biggest gain,which has important meaning to guide how to deploy an array in practice.We also should use the array with respect to the characteristics of the real ambient noise,especially in anisotropic noise field.展开更多
Ground subsidence induced by extraction of coal seam belowground brings about changes in surface environment leading to trough and pot-hole subsidence.Pot-hole subsidence is extremely hazardous and does not give any p...Ground subsidence induced by extraction of coal seam belowground brings about changes in surface environment leading to trough and pot-hole subsidence.Pot-hole subsidence is extremely hazardous and does not give any prior indication before its occurrence.In India,several pot-holes have occurred in the coal mines of South Eastern Coalfields Limited triggering the need for in-depth studies.In line with the requirement,literature review and field investigations were conducted to develop an in-depth understanding of various parameters influencing the occurrence of pot-holes.The critical parameters identified were rock to soil ratio,depth to height of extraction ratio,brittleness index of rock and rock density.Risk assessment of pot-hole subsidence has been done by developing an empirical rating approach named as pot-hole subsidence rating(PHSR),involving the critical parameters with suitable corrections for certain structural and mining conditions to obtain corrected PHSR(CPHSR).CPHSR was then applied for all the 34pot-holes studied and it was found that all the pot-holes fall under Class I and Class II category of risk representing a very high to high risk class.An effort was made for the estimation of pot-hole depth utilizing the developed CPHSR in both the development and depillaring cases.The developed approach was found to yield consistent results in pot-hole depth prediction.展开更多
In this paper, we discuss mainly the properties of incompressible pairwise incomprcssiblc surfaccs in ahnost altcrnating link complcmcnts. Lct L bc a almost link and lct F be an incompressible pairwise incompressible ...In this paper, we discuss mainly the properties of incompressible pairwise incomprcssiblc surfaccs in ahnost altcrnating link complcmcnts. Lct L bc a almost link and lct F be an incompressible pairwise incompressible surface in S^3 - L. First, we give the properties that the surface F intersects with 2-spheres in S^3- L. The intersection consisting of a collection of circles and saddle-shaped discs is called a topological graph. One can compute the Euler Characteristic number of the surface by calculating the characteristic number of the graph. Next, we prove that if the graph is special simple, then the genus of the surface is zero.展开更多
The main goal of this paper is to investigate sound scattering from the sea surface, by Kuo＇s small perturbation method （SPM）, in the Persian Gulf＇s environmental conditions. Accordingly the SPM method is reviewed...The main goal of this paper is to investigate sound scattering from the sea surface, by Kuo＇s small perturbation method （SPM）, in the Persian Gulf＇s environmental conditions. Accordingly the SPM method is reviewed, then it is demonstrated how it can accurately model sound scattering from the sea surface. Since in Kuo＇s approach, the effects of surface roughness and sub-surface bubble plumes on incident sounds can be studied separately, it is possible to investigate the importance of each mechanism in various scattering regimes. To conduct this study, wind and wave information reported by Arzanah station as well as some numerical atmospheric models for the Persian Gulf are presented and applied to examine sound scattering from the sea surface in the Persian Gulf region. Plots of scattering strength by Kuo＇s SPM method versus grazing angle for various frequencies, wave heights, and wind speeds are presented. The calculated scattering strength by the SPM method for various frequencies and wind speeds are compared against the results of critical sea tests 7 （CST-7）. The favorable agreement achieved for sound scattering in the Persian Gulf region is indicative of the fact that the SPM method can quite accurately model and predict sound scattering from the sea surface.展开更多
基金Funded by the National Science and Technology Major Project of the Ministry of Science and Technology of China(2015ZX06004001-002)the Postgraduate Research and Innovation Project of the University of South China(2017XCX11)
文摘To improve the oxidation resistance and corrosion resistance of Zr-4 alloy, titanium nitride （TIN） coatings were prepared on the Zr-4 alloy with a TiN ceramic target with different ratios of N2. Microstructure and high-temperature properties of the TiN coated samples were studied by scanning electron microscopy （SEM）, energy dispersive spectrometer （EDS）, X-ray diffraction meter （XRD）, X-ray photoelectron spectroscopy （XPS）, heat treatment furnace and autoclaves, respectively. The x value of the TiN coatings （TiN） ranges from 0.96 to 1.33. After the introduction of N2, TiN coating exhibits a weak （200） plane and a preferred （111） orientation. The coating prepared with an N2 flow ratio of 15% shows an optimal oxidation resistance in the atmospheric environment at 800 ℃. In either 1 200 ℃ steam environment for one hour, or deionized water at 360 ℃ and a pressure of 18.6 Mpa for 16 d, the opitimized TiN coated samples have no delamination or spallation; and the gains in the masses of samples are much smaller than Zr-4 alloy. These results demonstrate the effectiveness of the optimized TiN coating as the protective coating on the Zr-4 alloy under extreme conditons.
基金Project supported by the National Natural Science Foundation of China （Grant No 50475035）, the Doctoral Program of Higher Education of China （Grant No 20050213035） and the Program for New Century Excellent Talents in University of China （Grant No NCET-05-0348）.
文摘annular beam tri-heterodyne confocal microscope has been proposed to improve the anti-environmental interference capability and the resolution of a eonfoeal microscope. It simultaneously detects far-, on-, and near-focus signals with given phase differences by dividing the measured light path of the eonfoeal microscope into three sub-paths （signals）. Pair-wise real-time heterodyne subtraction of the three signals is used to improve the anti-environmental interference capability, axial resolution, and linearity; and a shaped annular beam super-resolution technique is used to improve lateral resolution. Theoretical analyses and preliminary experiments indicate that an axial resolution of about 1 nm can be achieved with a shaped annular beam tri-heterodyne confoeal microscope and its lateral resolution can be better than 0.2 um for A = 632.8 nm, the numerical aperture of the lens of the microscope is NA = 0.85, and the normalized radius e = 0.5.
基金Supported by the National Natural Science Foundation of China under Grant No.50909028
文摘Acoustic vector sensor consists of pressure and particle velocity sensors,which measure the three-dimensional acoustic particle velocity,as well as the pressure at one location at the same time.By preserving the amplitude and phase information of the pressure and particle velocity,they possess a number of advantages over traditional scalar sensors.Signal-to-noise ratio (SNR) gain (which is often called array gain) is one of such advantages and is always interested by all of us.But it is not unchangeable if the spatial correlation of the noise field varies.Much more important,it is difficult to be given if the noise becomes complex.In this paper,spatial correlation of the vector field of isotropic volume-noise and surface-generated noise has been introduced briefly.Based on the results,the combined SNR output of a vector linear array is investigated and the maximum gain is given in the specified noise.Computer simulation shows that the output of one array in the same noise is not the same in different gestures.And then we find the best gesture through SNR calculation and obtain the biggest gain,which has important meaning to guide how to deploy an array in practice.We also should use the array with respect to the characteristics of the real ambient noise,especially in anisotropic noise field.
基金Financial support for this work is provided by M/s SECL,CIL,India
文摘Ground subsidence induced by extraction of coal seam belowground brings about changes in surface environment leading to trough and pot-hole subsidence.Pot-hole subsidence is extremely hazardous and does not give any prior indication before its occurrence.In India,several pot-holes have occurred in the coal mines of South Eastern Coalfields Limited triggering the need for in-depth studies.In line with the requirement,literature review and field investigations were conducted to develop an in-depth understanding of various parameters influencing the occurrence of pot-holes.The critical parameters identified were rock to soil ratio,depth to height of extraction ratio,brittleness index of rock and rock density.Risk assessment of pot-hole subsidence has been done by developing an empirical rating approach named as pot-hole subsidence rating(PHSR),involving the critical parameters with suitable corrections for certain structural and mining conditions to obtain corrected PHSR(CPHSR).CPHSR was then applied for all the 34pot-holes studied and it was found that all the pot-holes fall under Class I and Class II category of risk representing a very high to high risk class.An effort was made for the estimation of pot-hole depth utilizing the developed CPHSR in both the development and depillaring cases.The developed approach was found to yield consistent results in pot-hole depth prediction.
基金Supported by NSF of China(10171024)Supported by Liaoning Educational Committee(05L208)
文摘In this paper, we discuss mainly the properties of incompressible pairwise incomprcssiblc surfaccs in ahnost altcrnating link complcmcnts. Lct L bc a almost link and lct F be an incompressible pairwise incompressible surface in S^3 - L. First, we give the properties that the surface F intersects with 2-spheres in S^3- L. The intersection consisting of a collection of circles and saddle-shaped discs is called a topological graph. One can compute the Euler Characteristic number of the surface by calculating the characteristic number of the graph. Next, we prove that if the graph is special simple, then the genus of the surface is zero.
文摘The main goal of this paper is to investigate sound scattering from the sea surface, by Kuo＇s small perturbation method （SPM）, in the Persian Gulf＇s environmental conditions. Accordingly the SPM method is reviewed, then it is demonstrated how it can accurately model sound scattering from the sea surface. Since in Kuo＇s approach, the effects of surface roughness and sub-surface bubble plumes on incident sounds can be studied separately, it is possible to investigate the importance of each mechanism in various scattering regimes. To conduct this study, wind and wave information reported by Arzanah station as well as some numerical atmospheric models for the Persian Gulf are presented and applied to examine sound scattering from the sea surface in the Persian Gulf region. Plots of scattering strength by Kuo＇s SPM method versus grazing angle for various frequencies, wave heights, and wind speeds are presented. The calculated scattering strength by the SPM method for various frequencies and wind speeds are compared against the results of critical sea tests 7 （CST-7）. The favorable agreement achieved for sound scattering in the Persian Gulf region is indicative of the fact that the SPM method can quite accurately model and predict sound scattering from the sea surface.
