Spectral unmixing analysis for hyperspectral images aims at estimating the pure constituent materials (called endmembers) in each mixed pixel and their corresponding fractional abundances. In this article, we use a semi-supervised approach based on a large spectral database. It aims at finding the optimal subset of spectral signatures in a large spectral library that can best model each mixed pixel in the scene and computes the fractional abundance which every spectral signal corresponds to. We use l2 - l1 sparse regression technical which has the advantage of being convex. Then we adopt split Bregman iteration algorithm to solve the problem. It converges quickly and the value of regularization parameter could remain constant during iterations. Our experiments use simulated pure and mixed pixel hyperspectral images of Hubble Space Telescope. The endmembers selected in the solution are the real materials' spectrums in the simulated data and the approximations of their corresponding fractional abundances are close to the true situation. The results indicate the algorithm works well.
{"title":"Sparse unmixing analysis for hyperspectral imagery of space objects","authors":"Zhenwei Shi, Xinya Zhai, Durengjan Borjigen, Zhi-guo Jiang","doi":"10.1117/12.900271","DOIUrl":"https://doi.org/10.1117/12.900271","url":null,"abstract":"Spectral unmixing analysis for hyperspectral images aims at estimating the pure constituent materials (called endmembers) in each mixed pixel and their corresponding fractional abundances. In this article, we use a semi-supervised approach based on a large spectral database. It aims at finding the optimal subset of spectral signatures in a large spectral library that can best model each mixed pixel in the scene and computes the fractional abundance which every spectral signal corresponds to. We use l2 - l1 sparse regression technical which has the advantage of being convex. Then we adopt split Bregman iteration algorithm to solve the problem. It converges quickly and the value of regularization parameter could remain constant during iterations. Our experiments use simulated pure and mixed pixel hyperspectral images of Hubble Space Telescope. The endmembers selected in the solution are the real materials' spectrums in the simulated data and the approximations of their corresponding fractional abundances are close to the true situation. The results indicate the algorithm works well.","PeriodicalId":355017,"journal":{"name":"Photoelectronic Detection and Imaging","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133263221","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Precise ground target localization is an interesting problem and relevant not only for military but also for civilian applications, and this is expected to be an emerging field with many potential applications. Ground Target Location Using Loitering Munitions (LM) requires estimation of aircraft position and attitude to a high degree of accuracy, and data derived by processing sensor images might be useful for supplementing other navigation sensor information and increasing the reliability and accuracy of navigation estimates during this flight phase. This paper presents a method for high accuracy ground target localization using Loitering Munitions (LM) equipped with a video camera sensor. The proposed method is based on a satellite or aerial image matching technique. In order to acquire the target position of ground intelligently and rapidly and to improve the localization accuracy estimating the target position jointly with the systematic LM and camera attitude measurement errors, several techniques have been proposed. Firstly, ground target geo-location based on tray tracing was used for comparison against our approach. By proposed methods the calculation from pixel to world coordinates can be done. Then Hough transform was used to image alignment and a median filter was applied for removing small details which are visible from the sensed image but not visible from the reference image. Finally, A novel edge detection method and an image matching algorithm based on bifurcation extraction were proposed. This method did not require accurate knowledge of the aircraft position and attitude and high performance sensors, therefore it is especially suitable for LM which did not have capability to carry accurate sensors due to their limited play weight and power resources. The results of simulation experiments and theory analyzing demonstrate that high accuracy ground target localization is reached with low performance sensors, and achieve timely. The method is used in reconnaissance and surveillance missions, or applicable in any other environment with a relevantly structured clutter.
{"title":"High accuracy ground target location using loitering munitions platforms","authors":"Zhifei Wang, Hua Wang, Jing Han","doi":"10.1117/12.900519","DOIUrl":"https://doi.org/10.1117/12.900519","url":null,"abstract":"Precise ground target localization is an interesting problem and relevant not only for military but also for civilian applications, and this is expected to be an emerging field with many potential applications. Ground Target Location Using Loitering Munitions (LM) requires estimation of aircraft position and attitude to a high degree of accuracy, and data derived by processing sensor images might be useful for supplementing other navigation sensor information and increasing the reliability and accuracy of navigation estimates during this flight phase. This paper presents a method for high accuracy ground target localization using Loitering Munitions (LM) equipped with a video camera sensor. The proposed method is based on a satellite or aerial image matching technique. In order to acquire the target position of ground intelligently and rapidly and to improve the localization accuracy estimating the target position jointly with the systematic LM and camera attitude measurement errors, several techniques have been proposed. Firstly, ground target geo-location based on tray tracing was used for comparison against our approach. By proposed methods the calculation from pixel to world coordinates can be done. Then Hough transform was used to image alignment and a median filter was applied for removing small details which are visible from the sensed image but not visible from the reference image. Finally, A novel edge detection method and an image matching algorithm based on bifurcation extraction were proposed. This method did not require accurate knowledge of the aircraft position and attitude and high performance sensors, therefore it is especially suitable for LM which did not have capability to carry accurate sensors due to their limited play weight and power resources. The results of simulation experiments and theory analyzing demonstrate that high accuracy ground target localization is reached with low performance sensors, and achieve timely. The method is used in reconnaissance and surveillance missions, or applicable in any other environment with a relevantly structured clutter.","PeriodicalId":355017,"journal":{"name":"Photoelectronic Detection and Imaging","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116413905","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
With the development of terahertz related technologies, the terahertz imaging technology will show its greater practical value in more areas. In this paper, we describe a terahertz imaging system that uses a single pixel detector in combination with a series of random masks to enable high-speed image acquisition. The image formation is based on the theory of compressed sensing (CS). When the scene under view is compressible by an algorithm like JPEG or JPEG2000, the CS theory enables us to stably reconstruct an image of the scene from fewer measurements than the number of reconstructed pixels. In this manner, we achieve sub-Nyquist image acquisition. CS theory mainly includes signal sparse representation, encoding measurement and reconstruction algorithm. CS combines sampling and compression into a single non-adaptive linear measurement process. Rather than measuring pixel samples of the scene under view, we measure inner products between the scene and a set of test functions. CS permits the reconstruction of a N-by-N pixel image using much fewer than N2 measurements. This approach eliminates the need for raster scanning of the object or the terahertz beam, while maintaining the high sensitivity of a single-element detector. We demonstrate the concept using a backward wave oscillator (BWO) which is a continuous-wave terahertz source and get a preliminary test result.
{"title":"Single-pixel terahertz imaging via compressed sensing","authors":"Ya-qin Zhao, Liangliang Zhang, Guoteng Duan, Xiaohua Liu, Cunlin Zhang","doi":"10.1117/12.900486","DOIUrl":"https://doi.org/10.1117/12.900486","url":null,"abstract":"With the development of terahertz related technologies, the terahertz imaging technology will show its greater practical value in more areas. In this paper, we describe a terahertz imaging system that uses a single pixel detector in combination with a series of random masks to enable high-speed image acquisition. The image formation is based on the theory of compressed sensing (CS). When the scene under view is compressible by an algorithm like JPEG or JPEG2000, the CS theory enables us to stably reconstruct an image of the scene from fewer measurements than the number of reconstructed pixels. In this manner, we achieve sub-Nyquist image acquisition. CS theory mainly includes signal sparse representation, encoding measurement and reconstruction algorithm. CS combines sampling and compression into a single non-adaptive linear measurement process. Rather than measuring pixel samples of the scene under view, we measure inner products between the scene and a set of test functions. CS permits the reconstruction of a N-by-N pixel image using much fewer than N2 measurements. This approach eliminates the need for raster scanning of the object or the terahertz beam, while maintaining the high sensitivity of a single-element detector. We demonstrate the concept using a backward wave oscillator (BWO) which is a continuous-wave terahertz source and get a preliminary test result.","PeriodicalId":355017,"journal":{"name":"Photoelectronic Detection and Imaging","volume":"112 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116587122","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper introduces a novel approach for post-processing of depth map which enhances the depth map resolution in order to achieve visually pleasing 3D models from a new monocular 2D/3D imaging system consists of a Photonic mixer device (PMD) range camera and a standard color camera. The proposed method adopts the revolutionary inversion theory framework called Compressive Sensing (CS). The depth map of low resolution is considered as the result of applying blurring and down-sampling techniques to that of high-resolution. Based on the underlying assumption that the high-resolution depth map is compressible in frequency domain and recent theoretical work on CS, the high-resolution version can be estimated and furthermore reconstructed via solving non-linear optimization problem. And therefore the improved depth map reconstruction provides a useful help to build an improved 3D model of a scene. The experimental results on the real data are presented. In the meanwhile the proposed scheme opens new possibilities to apply CS to a multitude of potential applications on various multimodal data analysis and processing.
{"title":"Depth map resolution enhancement for 2D/3D imaging system via compressive sensing","authors":"J. Han, O. Loffeld, K. Hartmann","doi":"10.1117/12.901006","DOIUrl":"https://doi.org/10.1117/12.901006","url":null,"abstract":"This paper introduces a novel approach for post-processing of depth map which enhances the depth map resolution in order to achieve visually pleasing 3D models from a new monocular 2D/3D imaging system consists of a Photonic mixer device (PMD) range camera and a standard color camera. The proposed method adopts the revolutionary inversion theory framework called Compressive Sensing (CS). The depth map of low resolution is considered as the result of applying blurring and down-sampling techniques to that of high-resolution. Based on the underlying assumption that the high-resolution depth map is compressible in frequency domain and recent theoretical work on CS, the high-resolution version can be estimated and furthermore reconstructed via solving non-linear optimization problem. And therefore the improved depth map reconstruction provides a useful help to build an improved 3D model of a scene. The experimental results on the real data are presented. In the meanwhile the proposed scheme opens new possibilities to apply CS to a multitude of potential applications on various multimodal data analysis and processing.","PeriodicalId":355017,"journal":{"name":"Photoelectronic Detection and Imaging","volume":"73 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115396472","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
B. Duan, D. Hei, G. Song, Jiming Ma, Zhan-hong Zhang, Changcai Han, Yan Song, Ming Zhou, Lan Lei
In this paper, based on the mechanism of CCD camera, an event-based simulation method of γ-ray-induced transient noise was developed, which applying MCNP5 Code based on Monte Carlo methods. On the mono-energy γ-ray sources, the transient noises of two different CCD cameras have been measured at different doses (from 0.001mR to 1mR) and different incidence angles. The 60Co and 137Cs were used as the mono-energy γ-ray sources, and the Compton Scattering technique were adopted to get lower energy γ-ray sources. In order to get the pure transient noise induced by γ-ray, a method was advanced for extracting the transient noise from the image mixed the background noise. And the transient noise was characterized, including the number of noise clusters, the noise intensity spectrum and the size spectrum of noise clusters. The variation characteristics of noise have been draw from the simulation and experiment, which induced by γ-rays of different dose, or different energy or different incidence angle.
{"title":"Study on transient noise of CCD camera induced by γ-ray","authors":"B. Duan, D. Hei, G. Song, Jiming Ma, Zhan-hong Zhang, Changcai Han, Yan Song, Ming Zhou, Lan Lei","doi":"10.1117/12.901769","DOIUrl":"https://doi.org/10.1117/12.901769","url":null,"abstract":"In this paper, based on the mechanism of CCD camera, an event-based simulation method of γ-ray-induced transient noise was developed, which applying MCNP5 Code based on Monte Carlo methods. On the mono-energy γ-ray sources, the transient noises of two different CCD cameras have been measured at different doses (from 0.001mR to 1mR) and different incidence angles. The 60Co and 137Cs were used as the mono-energy γ-ray sources, and the Compton Scattering technique were adopted to get lower energy γ-ray sources. In order to get the pure transient noise induced by γ-ray, a method was advanced for extracting the transient noise from the image mixed the background noise. And the transient noise was characterized, including the number of noise clusters, the noise intensity spectrum and the size spectrum of noise clusters. The variation characteristics of noise have been draw from the simulation and experiment, which induced by γ-rays of different dose, or different energy or different incidence angle.","PeriodicalId":355017,"journal":{"name":"Photoelectronic Detection and Imaging","volume":"61 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121511447","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In the conventional method, the structural parameters of primary mirror are usually optimized just by the requirement of mechanical performance. Because the influences of structural parameters on thermal stability are not taken fully into account in this simple method, the lightweight optimum design of primary mirror usually brings the bad thermal stability, especially in the complex environment. In order to obtain better thermal stability, a new method about structure-thermal optimum design of tracking primary mirror is discussed. During the optimum process, both the lightweight ratio and thermal stability will be taken into account. The structure-thermal optimum is introduced into the analysis process and commenced after lightweight design as the secondary optimum. Using the engineering analysis of software ANSYS, a parameter finite element analysis (FEA) model of mirror is built. On the premise of appropriate lightweight ratio, the RMS of structure-thermal deformation of mirror surface and lightweight ratio are assigned to be state variables, and the maximal RMS of temperature gradient load to be object variable. The results show that certain structural parameters of tracking primary mirror have different influences on mechanical performance and thermal stability, even they are opposite. By structure-thermal optimizing, the optimized mirror model discussed in this paper has better thermal stability than the old one under the same thermal loads, which can drastically reduce difficulty in thermal control.
{"title":"Thermal optimum design for tracking primary mirror of Space Telescope","authors":"Haichao Pan, P. Ruan, Fu Li, Hongwei Wang","doi":"10.1117/12.899606","DOIUrl":"https://doi.org/10.1117/12.899606","url":null,"abstract":"In the conventional method, the structural parameters of primary mirror are usually optimized just by the requirement of mechanical performance. Because the influences of structural parameters on thermal stability are not taken fully into account in this simple method, the lightweight optimum design of primary mirror usually brings the bad thermal stability, especially in the complex environment. In order to obtain better thermal stability, a new method about structure-thermal optimum design of tracking primary mirror is discussed. During the optimum process, both the lightweight ratio and thermal stability will be taken into account. The structure-thermal optimum is introduced into the analysis process and commenced after lightweight design as the secondary optimum. Using the engineering analysis of software ANSYS, a parameter finite element analysis (FEA) model of mirror is built. On the premise of appropriate lightweight ratio, the RMS of structure-thermal deformation of mirror surface and lightweight ratio are assigned to be state variables, and the maximal RMS of temperature gradient load to be object variable. The results show that certain structural parameters of tracking primary mirror have different influences on mechanical performance and thermal stability, even they are opposite. By structure-thermal optimizing, the optimized mirror model discussed in this paper has better thermal stability than the old one under the same thermal loads, which can drastically reduce difficulty in thermal control.","PeriodicalId":355017,"journal":{"name":"Photoelectronic Detection and Imaging","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117164677","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Insulating oil is widely used in transformer and other large high-voltage electrical equipment.Its main functions are insulation, cooling and arc extinction. When the transformer runs, it may emit heat or discharge, which generate gas, micro water and trace metals in transformer oil. This will not only reduce the insulation capacity of insulating oil,and will greatly reduce the ability of its extinction, causing the transformers or other oil-filled electrical equipment appearing Internal latent malfunction, which would affect the operation of equipment. In this Paper, we simulate the transformer discharge effect to discharge in transformer oil. Then we use spectral theory and photo-spectroscopy technology to measure and analyse the oil sample, combining with IR absorption peaks of main fault characteristic gases, and qualitatively analyse CO, CO2, CH4, C2H6, C2H4, C2H2, H2 in gas mixture. The results show that the Fourier transform infrared spectroscopy can be very effective for analysing gases in transformer oil, which can quickly detect possible problems in the equipment.
{"title":"Research on gas within transformer oil based on photo-spectroscopy technology","authors":"Guicai Song, Y. Na, Q. Zhang, Wen-zong Shi","doi":"10.1117/12.900474","DOIUrl":"https://doi.org/10.1117/12.900474","url":null,"abstract":"Insulating oil is widely used in transformer and other large high-voltage electrical equipment.Its main functions are insulation, cooling and arc extinction. When the transformer runs, it may emit heat or discharge, which generate gas, micro water and trace metals in transformer oil. This will not only reduce the insulation capacity of insulating oil,and will greatly reduce the ability of its extinction, causing the transformers or other oil-filled electrical equipment appearing Internal latent malfunction, which would affect the operation of equipment. In this Paper, we simulate the transformer discharge effect to discharge in transformer oil. Then we use spectral theory and photo-spectroscopy technology to measure and analyse the oil sample, combining with IR absorption peaks of main fault characteristic gases, and qualitatively analyse CO, CO2, CH4, C2H6, C2H4, C2H2, H2 in gas mixture. The results show that the Fourier transform infrared spectroscopy can be very effective for analysing gases in transformer oil, which can quickly detect possible problems in the equipment.","PeriodicalId":355017,"journal":{"name":"Photoelectronic Detection and Imaging","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122384325","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fu Li, P. Ruan, Ting Li, Gang-zhou Xu, Di Lu, Haichao Pan
The carbon-carbon composite (CCC) was applied in order to design and fabricate much more predominant lunar optical telescope (LOT). The fabricating technics of CCC and machining technics of load-carrying cylinder assembly are introduced. The density of CCC is 1.73g/cm3, and the coefficient of thermal expansion is 0.5×10-6/°C. The thermal adaptability of LOT was analyzed, the operating temperature of LOT will be improved to -20°C~+40°C that the carbon-carbon cylinder is used. Finite element analysis of LOT with CCC cylinder was performed, and the results show that the first frequency of LOT is 185Hz. The machining and assembling of LOT have been performed. The vibration testing has been accomplished and the testing results are consistent with finite element analysis. The testing results show that load-carrying cylinder of CCC can stand the mechanical proof. All analysis and testing indicate that CCC can be competent for LOT.
{"title":"Application of carbon-carbon composite for load-carrying cylinder in lunar optical telescope","authors":"Fu Li, P. Ruan, Ting Li, Gang-zhou Xu, Di Lu, Haichao Pan","doi":"10.1117/12.900738","DOIUrl":"https://doi.org/10.1117/12.900738","url":null,"abstract":"The carbon-carbon composite (CCC) was applied in order to design and fabricate much more predominant lunar optical telescope (LOT). The fabricating technics of CCC and machining technics of load-carrying cylinder assembly are introduced. The density of CCC is 1.73g/cm3, and the coefficient of thermal expansion is 0.5×10-6/°C. The thermal adaptability of LOT was analyzed, the operating temperature of LOT will be improved to -20°C~+40°C that the carbon-carbon cylinder is used. Finite element analysis of LOT with CCC cylinder was performed, and the results show that the first frequency of LOT is 185Hz. The machining and assembling of LOT have been performed. The vibration testing has been accomplished and the testing results are consistent with finite element analysis. The testing results show that load-carrying cylinder of CCC can stand the mechanical proof. All analysis and testing indicate that CCC can be competent for LOT.","PeriodicalId":355017,"journal":{"name":"Photoelectronic Detection and Imaging","volume":"81 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122499895","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Rima Bao, Lu Tian, K. Zhao, Shouming Zhu, Li-ming Liu, Guozong Zhao
In this paper, the optical characteristics of crude oil samples from selected territories in Tuha oil field have been investigated with THz-TDS at room temperature in nitrogen environment. The absorption coefficient and refraction index of crude oil are calculated in the frequency range of 0.20~2.5 THz. No distinct absorption peak has been found in the spectra, which may result from the complexity of the constitution of the samples and the water content. The absorption coefficients increase with the content of wax in the samples with different slopes, which means the intensity of absorption in THz wave band increases with enhanced density of the sample and unaltered thickness. The average refractive indices were 0.62070, 0.59767 and 0.59290 corresponding to TuLuFan, ShanShan and WenMi territories, respectively. The refractive values show the phenomenon of abnormal dispersion, which meant the samples had the characters of strong selective absorption in this wave band. In contrast, we have also utilized Fourier transform infrared spectroscopy (FTIR) in the 400-4000cm-1 to measure the mid-IR absorption spectra, and the results revealed that the crude oil is more active in the range of Terahertz than in the mid-IR band. The experiments demonstrated that THz-TDS is a powerful tool to complement the conventional analytical approaches and can be applied to detect and analyze the features of the constituent in crude oil.
{"title":"Spectroscopy studies on the Tuha crude oil in the terahertz range","authors":"Rima Bao, Lu Tian, K. Zhao, Shouming Zhu, Li-ming Liu, Guozong Zhao","doi":"10.1117/12.900988","DOIUrl":"https://doi.org/10.1117/12.900988","url":null,"abstract":"In this paper, the optical characteristics of crude oil samples from selected territories in Tuha oil field have been investigated with THz-TDS at room temperature in nitrogen environment. The absorption coefficient and refraction index of crude oil are calculated in the frequency range of 0.20~2.5 THz. No distinct absorption peak has been found in the spectra, which may result from the complexity of the constitution of the samples and the water content. The absorption coefficients increase with the content of wax in the samples with different slopes, which means the intensity of absorption in THz wave band increases with enhanced density of the sample and unaltered thickness. The average refractive indices were 0.62070, 0.59767 and 0.59290 corresponding to TuLuFan, ShanShan and WenMi territories, respectively. The refractive values show the phenomenon of abnormal dispersion, which meant the samples had the characters of strong selective absorption in this wave band. In contrast, we have also utilized Fourier transform infrared spectroscopy (FTIR) in the 400-4000cm-1 to measure the mid-IR absorption spectra, and the results revealed that the crude oil is more active in the range of Terahertz than in the mid-IR band. The experiments demonstrated that THz-TDS is a powerful tool to complement the conventional analytical approaches and can be applied to detect and analyze the features of the constituent in crude oil.","PeriodicalId":355017,"journal":{"name":"Photoelectronic Detection and Imaging","volume":"91 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122598774","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper, a real time method for detecting multiple dim targets in deep space background is presented and special attention is paid to occlusion handling. We matched the stars in tow continuous images to get their speed at first and found moving target pairs through speed in both images, a kalman filter whose equation was updated by the centroid was adopted to track the target. The star's area was used to judge occlusion, a two Gaussian mixture model was build using the pixels' gray value of fusing region and we used the predicted value which the kalman filter given to detect the target. The model's parameters were estimated using the expectation-maximization method and applied to separate the target and the star as well as computing the precise centroid. Extensive experiments on real images sequences show that the proposed approach could effectively meet the requirements of the real-time detection with a low false alarm rate and a high detection probability, simulation results show that it can also create a accuracy centroid when occlusion happens.
{"title":"Research of real time dim target detection algorithm under occlusion in space background","authors":"Lei Li, Yanning Zhang, Jinqiu Sun, Rui Yao","doi":"10.1117/12.897575","DOIUrl":"https://doi.org/10.1117/12.897575","url":null,"abstract":"In this paper, a real time method for detecting multiple dim targets in deep space background is presented and special attention is paid to occlusion handling. We matched the stars in tow continuous images to get their speed at first and found moving target pairs through speed in both images, a kalman filter whose equation was updated by the centroid was adopted to track the target. The star's area was used to judge occlusion, a two Gaussian mixture model was build using the pixels' gray value of fusing region and we used the predicted value which the kalman filter given to detect the target. The model's parameters were estimated using the expectation-maximization method and applied to separate the target and the star as well as computing the precise centroid. Extensive experiments on real images sequences show that the proposed approach could effectively meet the requirements of the real-time detection with a low false alarm rate and a high detection probability, simulation results show that it can also create a accuracy centroid when occlusion happens.","PeriodicalId":355017,"journal":{"name":"Photoelectronic Detection and Imaging","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130985146","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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