Synchrotron polychromatic X-ray microdiffraction(micro-XRD) was applied to study in situ deformation twinning of commercially AZ31(Mg-3Al-1Zn) strip subjected to uniaxial tension.The morphology and growth of twins...Synchrotron polychromatic X-ray microdiffraction(micro-XRD) was applied to study in situ deformation twinning of commercially AZ31(Mg-3Al-1Zn) strip subjected to uniaxial tension.The morphology and growth of twins were analyzed in situ under the load level from 64 to 73 MPa.The X-ray microdiffraction data,collected on beamline 12.3.2 at the Advanced Light Source,were then used to map an area of 396μm x 200μm within the region of interest.The experimental set-up and X-ray diffraction microscopy with a depth resolution allow the position and orientation of each illuminated grain to be determined at the submicron size.A list of parent grains sorted by crystallographic orientation were selected to examine their twinning behavior.The results depict twin variant selection,local misorientation fluctuation and mosaic spread for multi-twins within the same parent grain.As load increases,the amplitude of misorientation fluctuation along twin trace keeps increasing.This is attributable to the accumulation of geometrically necessary dislocations.展开更多
This study adopted IKONOS remote sensing images and selected spectral characteristic areas, through regional pixel statistics and calculating weight coefficients of each band, processed the images with the spectral no...This study adopted IKONOS remote sensing images and selected spectral characteristic areas, through regional pixel statistics and calculating weight coefficients of each band, processed the images with the spectral normalized method, which made the features of islands, land and water features more obviously in the images. On this basis, the OTUS was used to determine the optimal segmentation threshold, and the normalization image binarization was made, thus the island coastline was extracted. This method used the characteristic curve method to separate the land and water, obtained the binarization images and maintained the original edge effectively. The coastline that was extracted by Binary Morphology was continuous, reliable and high signal-to-noise ratio. The results showed that this method could extract the coastline fast, simply and effectively, which had the practical value.展开更多
Boundary extraction of watershed is an important step in forest landscape research. The boundary of the upriver wa-tershed of the Hunhe River in the sub-alpine Qingyuan County of eastern Liaoning Province, China was e...Boundary extraction of watershed is an important step in forest landscape research. The boundary of the upriver wa-tershed of the Hunhe River in the sub-alpine Qingyuan County of eastern Liaoning Province, China was extracted by digital elevation modeling (DEM) data in ArcInfo8.1. Remote sensing image of the corresponding region was applied to help modify its copy according to Enhanced Thematic Mapper (ETM) image抯 profuse geomorphological structure information. Both the DEM-dependent boundary and modified copy were overlapped with county map and drainage network map to visually check the effects of result. Overlap of county map suggested a nice extraction of the boundary line since the two layers matched precisely, which indicated the DEM-dependent boundary by program was effective and precise. Further upload of drainage network showed discrepancies between the boundary and the drainage network. Altogether, there were three sections of the extraction result that needed to correct. Compared with this extraction boundary, the modified boundary had a better match to the drainage network as well as to the county map. Comprehensive analysis demonstrated that the program extraction has generally fine precision in position and excels the digitized result by hand. The errors of the DEM-dependant extraction are due to the fact that it is difficult for program to recognize sections of complex landform especially altered by human activities, but these errors are discernable and adjustable because the spatial resolution of ETM image is less than that of DEM. This study result proved that application of remote sensing information could help obtain better result when DEM method is used in extraction of watershed boundary.展开更多
There exists a Ghost region in the detection result of the traditional visual background extraction(ViBe)algorithm,and the foreground extraction is prone to false detection or missed detection due to environmental cha...There exists a Ghost region in the detection result of the traditional visual background extraction(ViBe)algorithm,and the foreground extraction is prone to false detection or missed detection due to environmental changes.Therefore,an improved ViBe algorithm based on adaptive detection of moving targets was proposed.Firstly,in the background model initialization process,the real background could be obtained by setting adjusting parameters in mean background modeling,and the ViBe background model was initialized by using the background.Secondly,in the foreground detection process,an adaptive radius threshold was introduced according to the scene change to adaptively detect the foreground.Finally,mathematical morphological close operation was used to fill the holes in the detection results.The experimental results show that the improved method can effectively suppress the Ghost region and detect the foreground target more completely under the condition of environmental changes.Compared with the traditional ViBe algorithm,the detection accuracy is improved by more than 10%,the false detection rate and the missed detection rate are reduced by 20% and 7% respectively.In addition,the improved method satisfies the real-time requirements.展开更多
A new singularity extraction technique is presented to calculate accurately the singular integrals in Time Domain Electric Field Integral Equation (TDEFIE).In singularity extraction pro- cedure,through the aid of the ...A new singularity extraction technique is presented to calculate accurately the singular integrals in Time Domain Electric Field Integral Equation (TDEFIE).In singularity extraction pro- cedure,through the aid of the first order Taylor series of time base function including time-retardation,the singularity of the integrand can be removed.The surface current density and backscattered far-field response of a conducting cube illuminated by a Gaussian plane wave is com- puted using the presented technique.Comparisons are made with the results obtained by the Inverse Discrete Fourier Transform (IDFT) of the frequency domain and the results obtained by using Ve- chinski's time averaging technique,which demonstrate that the presented method with this new time domain singularity extraction technique to solve TDEFIE is very accurate and stable.展开更多
A collocated finite volume method on unstructured meshes is introduced to simulate the viscoelastic flow of the polymer melt with viscous dissipation past a confined cylinder.The constitutive equation for the simulati...A collocated finite volume method on unstructured meshes is introduced to simulate the viscoelastic flow of the polymer melt with viscous dissipation past a confined cylinder.The constitutive equation for the simulations is non-isothermal FENE-P model,which is derived from the molecular theories.The temperature effect on the macroscopic fields(e.g.,velocity,stress) and microscopic fields(e.g.,molecular orientation,deformation,stretch) is investigated by comparison of isothermal and non-isothermal situations.This investigation indicates that temperature rise caused by viscous dissipation should not be neglected since it has significant effect on the macroscopic and microscopic properties of the polymer melt.展开更多
Objective To investigate the effects of stimulant for nucleotide-binding oligomerization domain 1 (NOD1) on secretion of proinflammatory chemokine/cytokines and insulin-dependent glucose uptake in human differentiat...Objective To investigate the effects of stimulant for nucleotide-binding oligomerization domain 1 (NOD1) on secretion of proinflammatory chemokine/cytokines and insulin-dependent glucose uptake in human differentiated adipocytes. Methods Adipose tissues were obtained from patients undergoing liposuction. Stromal vascular cells were extracted and differentiated into adipocytes. A specific ligand for NOD1, was administered to human adipocytes in culture. Nuclear factor-κB transcriptional activity and proinflammatory chemokine/cytokines production were determined by reporter plasmid assay and enzyme-linked immunosorbent assay, respectively. Insulin-stimulated glucose uptake was measured by 2-deoxy-D-[ 3 H] glucose uptake assay. Furthermore, chemokine/cytokine secretion and glucose uptake in adipocytes transfected with small interfering RNA (siRNA) targeting NOD1 upon stimulation of NOD1 ligand were analyzed. Results Nuclear factor-κB transcriptional activity and monocyte chemoattractant protein-1 (MCP-1), interleukin (IL)-6, and IL-8 secretion in human adipocytes were markedly increased stimulated with NOD1 ligand (all P〈0.01). Insulin-induced glucose uptake was decreased upon the activation of NOD1 (P〈0.05). NOD1 gene silencing by siRNA reduced NOD1 ligand-induced MCP-1, IL-6, and IL-8 release and increased insulin-induced glucose uptake (all P〈0.05). Conclusion NOD1 activation in adipocytes might be implicated in the onset of insulin resistance.展开更多
This paper proposes an image segmentation method based on the combination of the wavelet multi-scale edge detection and the entropy iterative threshold selection.Image for segmentation is divided into two parts by hig...This paper proposes an image segmentation method based on the combination of the wavelet multi-scale edge detection and the entropy iterative threshold selection.Image for segmentation is divided into two parts by high- and low-frequency.In the high-frequency part the wavelet multiscale was used for the edge detection,and the low-frequency part conducted on segmentation using the entropy iterative threshold selection method.Through the consideration of the image edge and region,a CT image of the thorax was chosen to test the proposed method for the segmentation of the lungs.Experimental results show that the method is efficient to segment the interesting region of an image compared with conventional methods.展开更多
The IEEE 802. 16 standard specifies the air interface of wireless metropolitan area network (WMAN), and aims to provide wireless broadband access for integrated voice and video services. This paper presents the effi...The IEEE 802. 16 standard specifies the air interface of wireless metropolitan area network (WMAN), and aims to provide wireless broadband access for integrated voice and video services. This paper presents the efficient design and implementation of fast Frouier transform (FFT) and inverse fast Frouier transform (IFFT) for the application in IEEE 802. 16d orthogoual frequency division multiplexing (OFDM) system. In this design, a novel pipeline structure for the branch of butterfly unit (BU) is proposed, which can improve the processing symbol rate by adding the number of branch flexibly. The symmetrical ping-pang structure of random access memory (RAM) is performed to increase the system throughput. Simulation results reveal that only with 1 branch of BU, the proposed FFF/IFFT design can almost achieve the maximum bandwidth requirement of IEEE 802. 16d OFDM system. And this design has been verified by FPGA and successfully implemented in the prototype of WiMAX transceiver.展开更多
In order to make the humanoid robot walk freely in complicated circumstance, the reliable capabilities for obtaining plane information from its surroundings are demanded. A system for extracting planes from data taken...In order to make the humanoid robot walk freely in complicated circumstance, the reliable capabilities for obtaining plane information from its surroundings are demanded. A system for extracting planes from data taken by stereo vision was presented, After the depth image was obtained, the pixels of each line were scanned and split into straight line segments. The neighbouring relation of line segments was kept in link structure. The groups of three line segments were selected as seed regions. A queue was maintained for storing seed regions, and then the plane region was expanded around the seed region. The process of region growing continued until the queue of seed regions was empty. After trimming, the edges of the planes became smooth. In the end, extracted planes were obtained. In the experiment, two models were used: pipe and stairs. Two planes in pipe mode/and six planes in stairs model were extracted exactly. The speed and precision of algorithm can satisfy the demands of humanoid robot's navigation.展开更多
Pornographic image/video recognition plays a vital role in network information surveillance and management. In this paper, its key techniques, such as skin detection, key frame extraction, and classifier design, etc.,...Pornographic image/video recognition plays a vital role in network information surveillance and management. In this paper, its key techniques, such as skin detection, key frame extraction, and classifier design, etc., are studied in compressed domain. A skin detection method based on data-mining in compressed domain is proposed firstly and achieves the higher detection accuracy as well as higher speed. Then, a cascade scheme of pornographic image recognition based on selective decision tree ensemble is proposed in order to improve both the speed and accuracy of recognition. A pornographic video oriented key frame extraction solution in compressed domain and an approach of pornographic video recognition are discussed respectively in the end.展开更多
The authors use a web crawler to retrieve all periodical articles from CNKI between the 1950 s and 2016 and then parse the abstracts of 293368 articles about grassland deterioration by word segmentation, location matc...The authors use a web crawler to retrieve all periodical articles from CNKI between the 1950 s and 2016 and then parse the abstracts of 293368 articles about grassland deterioration by word segmentation, location matching and other methods. The authors also construct a research hot regions extraction model of grassland deterioration in China based on a comprehensive research hot regions index of toponyms and then analyze the spatial pattern and dynamic change in research hot regions of grassland deterioration in China. The research shows the following:(1) The spatial heterogeneity of grassland deterioration in China can be effectively described by a model of grassland deterioration based on the comprehensive research hot regions index.(2) The research hot regions of grassland deterioration are mainly distributed in most regions of Inner Mongolia, Xinjiang, Qinghai, Tibet, Gansu and other provinces. The northeastern region of Inner Mongolia(such as Hulunbeier) and the eastern region of Inner Mongolia(such as Xilin Gol, Chifeng and Wulanchabu) are significant hot regions in the study of grassland deterioration.(3) The number of high research hot regions increases from 81 in the 1950 s to 99 in the 2000s; the area increases from 1.038 million km2 to 1.146 million km2. The degree of hot for grassland deterioration research in 197 counties showed an upward trend. This paper also discusses the relationship between the region of research hot regions and the region of grassland deterioration and then indicates the differences between them in time matching, space matching and concept matching.展开更多
Speed-adaptive full-order flux observer is the most promising flux estimator among all the sensorless control method.However,conventional speed-adaptive flux observer becomes unstable during regenerating operation at ...Speed-adaptive full-order flux observer is the most promising flux estimator among all the sensorless control method.However,conventional speed-adaptive flux observer becomes unstable during regenerating operation at low speed since induction motor is an observable system except dc excitation.Thus,the instability problem is caused by inappropriate designing of observer.Based on the eigenvalues of extended observer,this paper interprets unstable situation,that the eigenvalues of extended ob-server have a positive real part.Therefore,the observer cannot converge.Against the two different solutions for unstable prob-lem-positive real maintaining and current error augment,the proposed method based on the eigenvalue could unify these two solutions,which gives the complete stability condition for speed-adaptive full-order observer.It does a lot help in observer de-signing.The observer configured by this proposed method was verified in the torque controlling of 20 kW induction motor.According to the experiment result,with appropriate designing of observer,the unstable situation during regeneration mode could be completely overcome.展开更多
A spectral calibration technique, a data processing method and the importance of calibration and re-sampling methods for the spectral domain optical coherence tomography system were numerically studied, targeted to op...A spectral calibration technique, a data processing method and the importance of calibration and re-sampling methods for the spectral domain optical coherence tomography system were numerically studied, targeted to optical coherence tomography (OCT) signal processing implementation under graphics processing unit (GPU) architecture. Accurately, assigning the wavelength to each pixel of the detector is of paramount importance to obtain high quality images and increase signal to noise ratio (SNR). High quality imaging can be achieved by proper calibration methods, here performed by phase calibration and interpolation. SNR was assessed employing two approaches, single spectrum moving window averaging and consecutive spectra data averaging, to investigate the optimized method and factor for background noise reduction. It was demonstrated that the consecutive spectra averaging had better SNR performance.展开更多
A method of transmission and monitoring in local area network(LAN) for the welding seam video information of binocular vision welding robot is proposed.This paper uses MPEG-4 video CODEC functions of DivX,video for Wi...A method of transmission and monitoring in local area network(LAN) for the welding seam video information of binocular vision welding robot is proposed.This paper uses MPEG-4 video CODEC functions of DivX,video for Windows(VFW) video capture technology,multi-threaded network communication idea and WinSock Socket in Visual C++ 6.0.In the end,client/server(C/S) communication model based on TCP/IP protocol has been developed.Experimental results show that the method can achieve the multiple welding seam video's real-time transmission in LAN.Moreover,the Canny operator is used to realize the edge feature extraction of the seam image which is captured by the client,so that the edge of the seam extracted is continuous and clear.展开更多
基金Project(DP140102355)supported by the Australian Research Council(ARC)Project supported by the China Scholarship Council(CSC)
文摘Synchrotron polychromatic X-ray microdiffraction(micro-XRD) was applied to study in situ deformation twinning of commercially AZ31(Mg-3Al-1Zn) strip subjected to uniaxial tension.The morphology and growth of twins were analyzed in situ under the load level from 64 to 73 MPa.The X-ray microdiffraction data,collected on beamline 12.3.2 at the Advanced Light Source,were then used to map an area of 396μm x 200μm within the region of interest.The experimental set-up and X-ray diffraction microscopy with a depth resolution allow the position and orientation of each illuminated grain to be determined at the submicron size.A list of parent grains sorted by crystallographic orientation were selected to examine their twinning behavior.The results depict twin variant selection,local misorientation fluctuation and mosaic spread for multi-twins within the same parent grain.As load increases,the amplitude of misorientation fluctuation along twin trace keeps increasing.This is attributable to the accumulation of geometrically necessary dislocations.
文摘This study adopted IKONOS remote sensing images and selected spectral characteristic areas, through regional pixel statistics and calculating weight coefficients of each band, processed the images with the spectral normalized method, which made the features of islands, land and water features more obviously in the images. On this basis, the OTUS was used to determine the optimal segmentation threshold, and the normalization image binarization was made, thus the island coastline was extracted. This method used the characteristic curve method to separate the land and water, obtained the binarization images and maintained the original edge effectively. The coastline that was extracted by Binary Morphology was continuous, reliable and high signal-to-noise ratio. The results showed that this method could extract the coastline fast, simply and effectively, which had the practical value.
基金This work was supported by Knowledge Innovation Pro-gram Chinese Academy of Sciences (No. KZCX2-SW-320-3 & KZCX3-SW-425).
文摘Boundary extraction of watershed is an important step in forest landscape research. The boundary of the upriver wa-tershed of the Hunhe River in the sub-alpine Qingyuan County of eastern Liaoning Province, China was extracted by digital elevation modeling (DEM) data in ArcInfo8.1. Remote sensing image of the corresponding region was applied to help modify its copy according to Enhanced Thematic Mapper (ETM) image抯 profuse geomorphological structure information. Both the DEM-dependent boundary and modified copy were overlapped with county map and drainage network map to visually check the effects of result. Overlap of county map suggested a nice extraction of the boundary line since the two layers matched precisely, which indicated the DEM-dependent boundary by program was effective and precise. Further upload of drainage network showed discrepancies between the boundary and the drainage network. Altogether, there were three sections of the extraction result that needed to correct. Compared with this extraction boundary, the modified boundary had a better match to the drainage network as well as to the county map. Comprehensive analysis demonstrated that the program extraction has generally fine precision in position and excels the digitized result by hand. The errors of the DEM-dependant extraction are due to the fact that it is difficult for program to recognize sections of complex landform especially altered by human activities, but these errors are discernable and adjustable because the spatial resolution of ETM image is less than that of DEM. This study result proved that application of remote sensing information could help obtain better result when DEM method is used in extraction of watershed boundary.
基金National Natural Science Foundation of China(No.61761027)Postgraduate Education Reform Project of Lanzhou Jiaotong University(No.1600120101)。
文摘There exists a Ghost region in the detection result of the traditional visual background extraction(ViBe)algorithm,and the foreground extraction is prone to false detection or missed detection due to environmental changes.Therefore,an improved ViBe algorithm based on adaptive detection of moving targets was proposed.Firstly,in the background model initialization process,the real background could be obtained by setting adjusting parameters in mean background modeling,and the ViBe background model was initialized by using the background.Secondly,in the foreground detection process,an adaptive radius threshold was introduced according to the scene change to adaptively detect the foreground.Finally,mathematical morphological close operation was used to fill the holes in the detection results.The experimental results show that the improved method can effectively suppress the Ghost region and detect the foreground target more completely under the condition of environmental changes.Compared with the traditional ViBe algorithm,the detection accuracy is improved by more than 10%,the false detection rate and the missed detection rate are reduced by 20% and 7% respectively.In addition,the improved method satisfies the real-time requirements.
文摘A new singularity extraction technique is presented to calculate accurately the singular integrals in Time Domain Electric Field Integral Equation (TDEFIE).In singularity extraction pro- cedure,through the aid of the first order Taylor series of time base function including time-retardation,the singularity of the integrand can be removed.The surface current density and backscattered far-field response of a conducting cube illuminated by a Gaussian plane wave is com- puted using the presented technique.Comparisons are made with the results obtained by the Inverse Discrete Fourier Transform (IDFT) of the frequency domain and the results obtained by using Ve- chinski's time averaging technique,which demonstrate that the presented method with this new time domain singularity extraction technique to solve TDEFIE is very accurate and stable.
基金Supported by the National Natural Science Foundation of China(10590353 10871159) the National Basic Research Program of China(2005CB321704) the Doctoral Foundation of Northwestern Polytechnical University(CX200817)
文摘A collocated finite volume method on unstructured meshes is introduced to simulate the viscoelastic flow of the polymer melt with viscous dissipation past a confined cylinder.The constitutive equation for the simulations is non-isothermal FENE-P model,which is derived from the molecular theories.The temperature effect on the macroscopic fields(e.g.,velocity,stress) and microscopic fields(e.g.,molecular orientation,deformation,stretch) is investigated by comparison of isothermal and non-isothermal situations.This investigation indicates that temperature rise caused by viscous dissipation should not be neglected since it has significant effect on the macroscopic and microscopic properties of the polymer melt.
基金Supported by Grant from Department of Education of Liaoning Province(2008810)
文摘Objective To investigate the effects of stimulant for nucleotide-binding oligomerization domain 1 (NOD1) on secretion of proinflammatory chemokine/cytokines and insulin-dependent glucose uptake in human differentiated adipocytes. Methods Adipose tissues were obtained from patients undergoing liposuction. Stromal vascular cells were extracted and differentiated into adipocytes. A specific ligand for NOD1, was administered to human adipocytes in culture. Nuclear factor-κB transcriptional activity and proinflammatory chemokine/cytokines production were determined by reporter plasmid assay and enzyme-linked immunosorbent assay, respectively. Insulin-stimulated glucose uptake was measured by 2-deoxy-D-[ 3 H] glucose uptake assay. Furthermore, chemokine/cytokine secretion and glucose uptake in adipocytes transfected with small interfering RNA (siRNA) targeting NOD1 upon stimulation of NOD1 ligand were analyzed. Results Nuclear factor-κB transcriptional activity and monocyte chemoattractant protein-1 (MCP-1), interleukin (IL)-6, and IL-8 secretion in human adipocytes were markedly increased stimulated with NOD1 ligand (all P〈0.01). Insulin-induced glucose uptake was decreased upon the activation of NOD1 (P〈0.05). NOD1 gene silencing by siRNA reduced NOD1 ligand-induced MCP-1, IL-6, and IL-8 release and increased insulin-induced glucose uptake (all P〈0.05). Conclusion NOD1 activation in adipocytes might be implicated in the onset of insulin resistance.
基金Science Research Foundation of Yunnan Fundamental Research Foundation of Applicationgrant number:2009ZC049M+1 种基金Science Research Foundation for the Overseas Chinese Scholars,State Education Ministrygrant number:2010-1561
文摘This paper proposes an image segmentation method based on the combination of the wavelet multi-scale edge detection and the entropy iterative threshold selection.Image for segmentation is divided into two parts by high- and low-frequency.In the high-frequency part the wavelet multiscale was used for the edge detection,and the low-frequency part conducted on segmentation using the entropy iterative threshold selection method.Through the consideration of the image edge and region,a CT image of the thorax was chosen to test the proposed method for the segmentation of the lungs.Experimental results show that the method is efficient to segment the interesting region of an image compared with conventional methods.
基金Sponsored by the National Natural Science Foundation of China(Grant No.60425413)
文摘The IEEE 802. 16 standard specifies the air interface of wireless metropolitan area network (WMAN), and aims to provide wireless broadband access for integrated voice and video services. This paper presents the efficient design and implementation of fast Frouier transform (FFT) and inverse fast Frouier transform (IFFT) for the application in IEEE 802. 16d orthogoual frequency division multiplexing (OFDM) system. In this design, a novel pipeline structure for the branch of butterfly unit (BU) is proposed, which can improve the processing symbol rate by adding the number of branch flexibly. The symmetrical ping-pang structure of random access memory (RAM) is performed to increase the system throughput. Simulation results reveal that only with 1 branch of BU, the proposed FFF/IFFT design can almost achieve the maximum bandwidth requirement of IEEE 802. 16d OFDM system. And this design has been verified by FPGA and successfully implemented in the prototype of WiMAX transceiver.
基金Project(60776816) supported by the National Natural Science Foundation of China and Civil Aviation Administration of ChinaProject(8251064101000005) supported by the Natural Science Foundation of Guangdong Province,China
文摘In order to make the humanoid robot walk freely in complicated circumstance, the reliable capabilities for obtaining plane information from its surroundings are demanded. A system for extracting planes from data taken by stereo vision was presented, After the depth image was obtained, the pixels of each line were scanned and split into straight line segments. The neighbouring relation of line segments was kept in link structure. The groups of three line segments were selected as seed regions. A queue was maintained for storing seed regions, and then the plane region was expanded around the seed region. The process of region growing continued until the queue of seed regions was empty. After trimming, the edges of the planes became smooth. In the end, extracted planes were obtained. In the experiment, two models were used: pipe and stairs. Two planes in pipe mode/and six planes in stairs model were extracted exactly. The speed and precision of algorithm can satisfy the demands of humanoid robot's navigation.
基金Supported by the National Natural Science Foundation of China (No.60772069)863 High-Tech Project (2008AA01A313)
文摘Pornographic image/video recognition plays a vital role in network information surveillance and management. In this paper, its key techniques, such as skin detection, key frame extraction, and classifier design, etc., are studied in compressed domain. A skin detection method based on data-mining in compressed domain is proposed firstly and achieves the higher detection accuracy as well as higher speed. Then, a cascade scheme of pornographic image recognition based on selective decision tree ensemble is proposed in order to improve both the speed and accuracy of recognition. A pornographic video oriented key frame extraction solution in compressed domain and an approach of pornographic video recognition are discussed respectively in the end.
基金National Key Research and Development Plan Program(2016YFC0503701,2016YFB0501502)Key Project of High Resolution Earth Observation System(00-Y30B14-9001-14/16)
文摘The authors use a web crawler to retrieve all periodical articles from CNKI between the 1950 s and 2016 and then parse the abstracts of 293368 articles about grassland deterioration by word segmentation, location matching and other methods. The authors also construct a research hot regions extraction model of grassland deterioration in China based on a comprehensive research hot regions index of toponyms and then analyze the spatial pattern and dynamic change in research hot regions of grassland deterioration in China. The research shows the following:(1) The spatial heterogeneity of grassland deterioration in China can be effectively described by a model of grassland deterioration based on the comprehensive research hot regions index.(2) The research hot regions of grassland deterioration are mainly distributed in most regions of Inner Mongolia, Xinjiang, Qinghai, Tibet, Gansu and other provinces. The northeastern region of Inner Mongolia(such as Hulunbeier) and the eastern region of Inner Mongolia(such as Xilin Gol, Chifeng and Wulanchabu) are significant hot regions in the study of grassland deterioration.(3) The number of high research hot regions increases from 81 in the 1950 s to 99 in the 2000s; the area increases from 1.038 million km2 to 1.146 million km2. The degree of hot for grassland deterioration research in 197 counties showed an upward trend. This paper also discusses the relationship between the region of research hot regions and the region of grassland deterioration and then indicates the differences between them in time matching, space matching and concept matching.
文摘Speed-adaptive full-order flux observer is the most promising flux estimator among all the sensorless control method.However,conventional speed-adaptive flux observer becomes unstable during regenerating operation at low speed since induction motor is an observable system except dc excitation.Thus,the instability problem is caused by inappropriate designing of observer.Based on the eigenvalues of extended observer,this paper interprets unstable situation,that the eigenvalues of extended ob-server have a positive real part.Therefore,the observer cannot converge.Against the two different solutions for unstable prob-lem-positive real maintaining and current error augment,the proposed method based on the eigenvalue could unify these two solutions,which gives the complete stability condition for speed-adaptive full-order observer.It does a lot help in observer de-signing.The observer configured by this proposed method was verified in the torque controlling of 20 kW induction motor.According to the experiment result,with appropriate designing of observer,the unstable situation during regeneration mode could be completely overcome.
文摘A spectral calibration technique, a data processing method and the importance of calibration and re-sampling methods for the spectral domain optical coherence tomography system were numerically studied, targeted to optical coherence tomography (OCT) signal processing implementation under graphics processing unit (GPU) architecture. Accurately, assigning the wavelength to each pixel of the detector is of paramount importance to obtain high quality images and increase signal to noise ratio (SNR). High quality imaging can be achieved by proper calibration methods, here performed by phase calibration and interpolation. SNR was assessed employing two approaches, single spectrum moving window averaging and consecutive spectra data averaging, to investigate the optimized method and factor for background noise reduction. It was demonstrated that the consecutive spectra averaging had better SNR performance.
基金the National Natural Science Foundation of China (No.61165008)the Natural Science Foundation of Jiangxi Province (No.20114BAB206004)the Project of Jiangxi Provincial Education Department(No.GJJ12038)
文摘A method of transmission and monitoring in local area network(LAN) for the welding seam video information of binocular vision welding robot is proposed.This paper uses MPEG-4 video CODEC functions of DivX,video for Windows(VFW) video capture technology,multi-threaded network communication idea and WinSock Socket in Visual C++ 6.0.In the end,client/server(C/S) communication model based on TCP/IP protocol has been developed.Experimental results show that the method can achieve the multiple welding seam video's real-time transmission in LAN.Moreover,the Canny operator is used to realize the edge feature extraction of the seam image which is captured by the client,so that the edge of the seam extracted is continuous and clear.