摘要 :
A technique was needed to perform spectral analysis with arbitrary resolution bandwidths and with arbitrary band-center locations. A method was derived to realize band centers that are equally spaced on a log-frequency scale,and w...
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A technique was needed to perform spectral analysis with arbitrary resolution bandwidths and with arbitrary band-center locations. A method was derived to realize band centers that are equally spaced on a log-frequency scale,and with bandwidths that vary proportionally with the band centers,or that vary as the square-root of the band centers.
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This paper demonstrates a simple analytical technique for extraction of spectral radiance values for the solar panel and body from an unresolved spectral infrared signature of 3-axis stabilized low-earth orbit (LEO) satellites. It...
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This paper demonstrates a simple analytical technique for extraction of spectral radiance values for the solar panel and body from an unresolved spectral infrared signature of 3-axis stabilized low-earth orbit (LEO) satellites. It uses data collected by The Aerospace Corporation's Broad-band Array Spectrograph System (BASS) instrument at the Air Force Maui Optical and Supercomputing (AMOS) site. The observation conditions were such that the signatures were due to the emissive phenomenology and contribution of earthshine was negligible. The analysis is based on a two-facet orientation model of the satellite. This model captures the basic, known behavior of the satellite body and its solar panels. One facet points to nadir and the second facet tracks the sun. The facet areas are unknown. Special conditions are determined on the basis of observational geometry that allows separation of the spectral radiance values of the solar panel and body. These values remain unchanged (i.e., are invariant) under steady illumination conditions even if the signature appears different from one observation to another. In addition, they provide information on the individual spectral makeup of the satellite solar panel and body materials.
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The use of any infrared sensor for sky survey measurements is complicated by signals from objects in the solar system. The identification of planets is trivial but asteroids and other small bodies form a large class of objects whi...
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The use of any infrared sensor for sky survey measurements is complicated by signals from objects in the solar system. The identification of planets is trivial but asteroids and other small bodies form a large class of objects which cannot be recognized as readily. In the 8- to 30-micron region they are an especially significant possible source of signals. With a median period of 4.6 years, asteroid motions of about a quarter of a degree per day are typical, implying that each observation must be treated independently to properly identify asteroids. As infrared detectors become more sensitive, previously unknown asteroids will appear and must be identified as such. (Author)
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The final report contains details of two important aspects of direct-sequence spread-spectrum (DS/SS) systems: acquisition of the signature sequence and error performance evaluation.
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The majority of spectral imagery classifiers make a decision based on information from a particular spectrum, often the mean, which best represents the spectral signature of a particular target. It is known, however, that the spec...
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The majority of spectral imagery classifiers make a decision based on information from a particular spectrum, often the mean, which best represents the spectral signature of a particular target. It is known, however, that the spectral signature of a target can vary significantly due to differences in illumination conditions, target shape, and target material composition. Furthermore, many targets of interest are inherently mixed, as is the case with camouflaged military vehicles, leading to even greater variability. In this thesis, a detailed statistical analysis is performed on HYDICE imagery of Davis Monthan Air Force Base. Several hundred pixels are identified as belonging to one of eight target classes and the distribution of spectral radiance within each group is studied. It has been found that simple normal statistics do not adequately model either the total radiance or the single band spectral radiance distributions, both of which can have highly skewed histograms even when the spectral radiance is high. Goodness of fit tests are performed for maximum likelihood normal, lognormal, gamma, and Weibull distributions. It was discovered that lognormal statistics can model the total radiance and many single-band distributions reasonable well, possibly indicative of multiplicative noise features in remotely sensed spectral imagery.
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Acoustic imagery generated by the Naval Research Laboratory's ASCS (Acoustic Sediment Classification System) is analyzed using time-frequency methods. The ASCS Imagery is generated using normal-incidence acoustic data. Nonlinearit...
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Acoustic imagery generated by the Naval Research Laboratory's ASCS (Acoustic Sediment Classification System) is analyzed using time-frequency methods. The ASCS Imagery is generated using normal-incidence acoustic data. Nonlinearities in the propagating medium produce multiple harmonics in the return. Different components of the bottom and sub-bottom produce different spectral signatures, based on the harmonics that can be used to classify the bottom. Although the exact acoustic properties of the media may not be known, it is possible to segment the spectrally different components. This paper presents an efficient method for performing the time-frequency analysis. The tradeoffs between time and frequency resolution are examined and exploited to produce the best overall resolution. Examples using the ASCS data demonstrate its use for classification of acoustic imagery. Buried pipes, methane gas deposits, and other features can be differentiated using this method.
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Currently we designed and implemented a combined spectral and lifetime imaging system which combines the benefits of multiphoton microscopy, spectral discrimination, lifetime analysis and temporal information. This system has effi...
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Currently we designed and implemented a combined spectral and lifetime imaging system which combines the benefits of multiphoton microscopy, spectral discrimination, lifetime analysis and temporal information. This system has efficiencies of > 50% and capability to collect broad spectrums (from 380nm-700nm). We determined the fluorescence source under our imaging condition is from NADH by this combined spectral and lifetime imaging system. Furthermore, we validated the accuracy of our lifetime analysis method. Our preliminary results of metabolic mapping in different human breast cell lines via fluorescence lifetime measurement of Co-Enzyme NADH showed very interesting results in differences of the lifetime and contribution of bound NADH between human normal breast cell line (MCF10a) and human breast cancer cell lines (T47D and MBA-MD-231). A 2-Deoxy-D-glucose (2DG) perturbation study is underway to link these finds with glycolysis.
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On the basis of existing measuring equipment, acquired over the years, threelaboratories from the defense research and industry in Sweden and Norway have made co-operative efforts to examine the possibility of harmonizing their me...
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On the basis of existing measuring equipment, acquired over the years, threelaboratories from the defense research and industry in Sweden and Norway have made co-operative efforts to examine the possibility of harmonizing their measuring techniques. Since modern materials must fulfill specified quantitative physical requirements in widely different parts of the electromagnetic spectrum, it is essential that measurements taken by the laboratories concerned are of comparable accuracy, and that errors caused by different measuring techniques are eliminated in so far as they are of practical significance. First, a complete overview was prepared for the equipment and the measuring procedures used by the parties. Second, comparative measurements were carried out in order to establish the level of descrepancies involved. Third, these results served as guides for harmonization of the measuring techniques.
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Recently, object detection based on hyperspectral sensors in support of autonomous robotics navigation has been of great interest. Hyperspectral sensors have been widely used for automatic target detection in military applications...
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Recently, object detection based on hyperspectral sensors in support of autonomous robotics navigation has been of great interest. Hyperspectral sensors have been widely used for automatic target detection in military applications, mainly because a wealth of spectral information can be obtained through a large number of narrow contiguous spectral channels (often over a hundred). The main purpose of this report is to present detection techniques based on hyperspectral sensing that can effectively identify potentially harmful objects to UGV navigation. The hyperspectral detection techniques used are built on the basic premise that the spectral signatures of objects of interest are in general different than background materials, and the objects of interest can be identified from their surrounding background materials based on spectral analysis of the hyperspectral data. In this report, we first present detailed information on two hyperspectral sensors-a dual band hyperspectral imager and an acousto-optic tunable filter imager that provide hyperspectral data in the infrared and visible bands, respectively. Several anomaly detection and classification techniques newly developed by ARL are then introduced and applied to the hyperspectral data to identify potential obstacles to robotics navigation. Detection performance for each technique is included in this report.
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