摘要 :
Ballistic testing was conducted on two composite materials: 8HS satin weave S-glass fiber and plain weave Aramid (Kevlar® KM2 600 Denier) fiber, both with a UAF-472 polyurethane thermoplastic matrix. The goals of the ballistic te...
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Ballistic testing was conducted on two composite materials: 8HS satin weave S-glass fiber and plain weave Aramid (Kevlar® KM2 600 Denier) fiber, both with a UAF-472 polyurethane thermoplastic matrix. The goals of the ballistic tests were to determine the effect of matrix material, shot dependency with regard to shot-to-shot distance, degree of penetration from previous shots, and delamination effects of previous shots on the ballistic limit of the material. The measure of performance for each ballistic limit was the projectile velocity with a 50% probability of completely penetrating the armor material, known as V_(50). The ballistic limit was determined by a three-phase optimal design test method, called 3-Pod. The delamination extent was determined by an audiovisual tap test. All plates were 0.25 inches thick and shots were conducted with no obliquity. This investigation was in response to previous research which showed mixed results in the ballistic limit with delamination overlap. The current research found a statistically significant increase in the ballistic limit for Aramid (but mixed results for S-glass) fiber materials in regard to secondary shots. For both materials, there were overall ballistic limit increases when compared to previous research using the same fiber, but with a different matrix.
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摘要 :
Ballistic testing was conducted on two composite materials: 8HS satin weave S-glass fiber and plain weave Aramid (Kevlar® KM2 600 Denier) fiber, both with a UAF-472 polyurethane thermoplastic matrix. The goals of the ballistic te...
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Ballistic testing was conducted on two composite materials: 8HS satin weave S-glass fiber and plain weave Aramid (Kevlar® KM2 600 Denier) fiber, both with a UAF-472 polyurethane thermoplastic matrix. The goals of the ballistic tests were to determine the effect of matrix material, shot dependency with regard to shot-to-shot distance, degree of penetration from previous shots, and delamination effects of previous shots on the ballistic limit of the material. The measure of performance for each ballistic limit was the projectile velocity with a 50% probability of completely penetrating the armor material, known as V_(50). The ballistic limit was determined by a three-phase optimal design test method, called 3-Pod. The delamination extent was determined by an audiovisual tap test. All plates were 0.25 inches thick and shots were conducted with no obliquity. This investigation was in response to previous research which showed mixed results in the ballistic limit with delamination overlap. The current research found a statistically significant increase in the ballistic limit for Aramid (but mixed results for S-glass) fiber materials in regard to secondary shots. For both materials, there were overall ballistic limit increases when compared to previous research using the same fiber, but with a different matrix.
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摘要 :
Ballistic testing was conducted on two composite materials: 8HS satin weave S-glass fiber and plain weave Aramid (Kevlar® KM2 600 Denier) fiber, both with a UAF-472 polyurethane thermoplastic matrix. The goals of the ballistic te...
展开
Ballistic testing was conducted on two composite materials: 8HS satin weave S-glass fiber and plain weave Aramid (Kevlar® KM2 600 Denier) fiber, both with a UAF-472 polyurethane thermoplastic matrix. The goals of the ballistic tests were to determine the effect of matrix material, shot dependency with regard to shot-to-shot distance, degree of penetration from previous shots, and delamination effects of previous shots on the ballistic limit of the material. The measure of performance for each ballistic limit was the projectile velocity with a 50% probability of completely penetrating the armor material, known as V_(50). The ballistic limit was determined by a three-phase optimal design test method, called 3-Pod. The delamination extent was determined by an audiovisual tap test. All plates were 0.25 inches thick and shots were conducted with no obliquity. This investigation was in response to previous research which showed mixed results in the ballistic limit with delamination overlap. The current research found a statistically significant increase in the ballistic limit for Aramid (but mixed results for S-glass) fiber materials in regard to secondary shots. For both materials, there were overall ballistic limit increases when compared to previous research using the same fiber, but with a different matrix.
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As aircraft designs aim for higher aerodynamic efficiency, the structures become more flexible, requiring additional features to alleviate the loads encountered from gusts and maneuvers. With the additional feature of alleviating ...
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As aircraft designs aim for higher aerodynamic efficiency, the structures become more flexible, requiring additional features to alleviate the loads encountered from gusts and maneuvers. With the additional feature of alleviating loads, it is preferable to minimize the change to the original flight trajectory tracking performance of the aircraft by exploiting redundant control effectors. In this work, a dynamic control allocation method for maneuver and gust load alleviation is proposed for flexible aircraft. The control architecture decouples the two objectives of load alleviation and rigid body trajectory tracking by exploiting the null space between the input and the rigid body output. A reduced-dimension null space variable is established and is optimally used to control the flexible output within user-defined bounds. A receding horizon approach is proposed to account for stochastic gust disturbances and maneuvers with limited preview. The proposed method is demonstrated through numerical simulations on a linearized model of the University of Michigan X-HALE aircraft.
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摘要 :
As aircraft designs aim for higher aerodynamic efficiency, the structures become more flexible, requiring additional features to alleviate the loads encountered from gusts and maneuvers. With the additional feature of alleviating ...
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As aircraft designs aim for higher aerodynamic efficiency, the structures become more flexible, requiring additional features to alleviate the loads encountered from gusts and maneuvers. With the additional feature of alleviating loads, it is preferable to minimize the change to the original flight trajectory tracking performance of the aircraft by exploiting redundant control effectors. In this work, a dynamic control allocation method for maneuver and gust load alleviation is proposed for flexible aircraft. The control architecture decouples the two objectives of load alleviation and rigid body trajectory tracking by exploiting the null space between the input and the rigid body output. A reduced-dimension null space variable is established and is optimally used to control the flexible output within user-defined bounds. A receding horizon approach is proposed to account for stochastic gust disturbances and maneuvers with limited preview. The proposed method is demonstrated through numerical simulations on a linearized model of the University of Michigan X-HALE aircraft.
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Abstract: Neural and stochastic models for signal classification generate output probabilities to indicate whether or not their inputs are members of the modeled class. This paper presents a feature enhancing neu...
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Abstract: Neural and stochastic models for signal classification generate output probabilities to indicate whether or not their inputs are members of the modeled class. This paper presents a feature enhancing neural network with weights based on the modeled class which can improve the classification performance of single output classifiers, by increasing output probabilities for members of the modeled class or decreasing output probabilities for non- members. The neural network is demonstrated as a front-end for multi-layer perceptron and semi-continuous hidden Markov model based classifiers for speech recognition applications. It is unique in that the weights and width of the input layer adapt based on extracted characteristics from the input speech signal. The connectionist architecture is motivated by the highly successful time-delay neural network and the desire to find efficient training procedures for class-dependent, short-time transformations. The weights are determined using a principal component analysis process and can be found by applying iterative or conventional algorithms. The neural network reduces false acceptances by more than one-third for a defined mono-syllable keyword spotting application using a semi-continuous hidden Markov model based system. An evaluation of the neural network as a front-end for multi-layer perceptron based classifiers which distinguish a word from confusable words is also presented. !32
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Neural and stochastic models for signal classification generate output probabilities to indicate whether or not their inputs are members of the modeled class. This paper presents a feature enhancing neural network with weights bas...
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Neural and stochastic models for signal classification generate output probabilities to indicate whether or not their inputs are members of the modeled class. This paper presents a feature enhancing neural network with weights based on the modeled class which can improve the classification performance of single output classifiers, by increasing output probabilities for members of the modeled class or decreasing output probabilities for non- members. The neural network is demonstrated as a front-end for multi-layer perceptron and semi-continuous hidden Markov model based classifiers for speech recognition applications. It is unique in that the weights and width of the input layer adapt based on extracted characteristics from the input speech signal. The connectionist architecture is motivated by the highly successful time-delay neural network and the desire to find efficient training procedures for class-dependent, short-time transformations. The weights are determined using a principal component analysis process and can be found by applying iterative or conventional algorithms. The neural network reduces false acceptances by more than one-third for a defined mono-syllable keyword spotting application using a semi-continuous hidden Markov model based system. An evaluation of the neural network as a front-end for multi-layer perceptron based classifiers which distinguish a word from confusable words is also presented.
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The digital morphological skeleton representation provides a means of improving lossless coding in a communication system. This is due to the observation that the entropy of a morphological skeleton is less than its original image...
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The digital morphological skeleton representation provides a means of improving lossless coding in a communication system. This is due to the observation that the entropy of a morphological skeleton is less than its original image. One way to improve coding efficiency is to minimize the morphological skeleton representation by choosing a more appropriate structuring element. For an image with consistent shape distribution such as a texture pattern, a more efficient and useful skeleton representation is expected. Analysis of simulated and natural image patterns show the activated points in a morphological skeleton to range between 30 and 327 points using different structuring elements. A procedure is proposed which allows for the selection of a more effective structuring element from a basis set of structuring elements. The decision process is based on the minimum-distance measurement in a multiprototype pattern classification. The structuring element for morphological skeletonization is from the closest match between the chain code edge vector and the basis set of structuring elements. The proposed procedure represents an organized means for choosing a more meaningful structuring element for morphological analysis. It is shown that a significant reduction in the number of required activated skeleton points will result for morphological skeletonization.
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Abstract: The digital morphological skeleton representation provides a means of improving lossless coding in a communication system. This is due to the observation that the entropy of a morphological skeleton is ...
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Abstract: The digital morphological skeleton representation provides a means of improving lossless coding in a communication system. This is due to the observation that the entropy of a morphological skeleton is less than its original image. One way to improve coding efficiency is to minimize the morphological skeleton representation by choosing a more appropriate structuring element. For an image with consistent shape distribution such as a texture pattern, a more efficient and useful skeleton representation is expected. Analysis of simulated and natural image patterns show the activated points in a morphological skeleton to range between 30 and 327 points using different structuring elements. A procedure is proposed which allows for the selection of a more effective structuring element from a basis set of structuring elements. The decision process is based on the minimum-distance measurement in a multiprototype pattern classification. The structuring element for morphological skeletonization is from the closest match between the chain code edge vector and the basis set of structuring elements. The proposed procedure represents an organized means for choosing a more meaningful structuring element for morphological analysis. It is shown that a significant reduction in the number of required activated skeleton points will result for morphological skeletonization. !11
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This paper addresses the problem of structure element selection in the context of a morphological based grayscale image communication system. The morphological skeleton representation in discrete space provides a means of lossless...
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This paper addresses the problem of structure element selection in the context of a morphological based grayscale image communication system. The morphological skeleton representation in discrete space provides a means of lossless coding, and the coding efficiency is further improved in its minimized version by choosing a more appropriate structuring element. For an image with consistent shape distribution such as a texture pattern, a more efficient and useful skeleton representation is expected. Analysis of simulated and natural image patterns show the activated points in a morphological skeleton range between 30 and 327 points using different structuring elements. A procedure is proposed which allows for the selection of a more effective structuring element from a basis set of structuring elements. The decision process of the multiprototype pattern classification is based on the minimum-distance measurement between the chain code edge vector of object and the basis set of structuring elements. For a grayscale image communication scheme, the binary morphological skeleton transformation provides a progressive transmission framework. This framework is based on the bit plane decomposition with Gray code mapping. The progressive communication system is useful for searching image databases over a narrowband communication channel. Once the image of interest is found, the progressive communication system can provide complete knowledge of the image without loss of any information. The proposed bit plane skeleton transmission system achieves data compression rates from 2.36 to 4.28 in this study, while the original image can be reconstructed exactly using the entire set of decomposed bit planes.
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