In practical communication and radar systems, the phase of the received signal is random, the arrival time is unknown, the lasting time is limited and the SNR is often very low. In order to realize the detection of th...In practical communication and radar systems, the phase of the received signal is random, the arrival time is unknown, the lasting time is limited and the SNR is often very low. In order to realize the detection of the signal, the method of using a group of nonlinear differential equations is presented. The theory of this chaos-based detection is analyzed. Computer simulation indicates that the shortest lasting time of the transient signal that can be detected out is 12 periods, the detection error of arrival time is less than 7/8 signal＇ s period, the detection characteristics are got using Monte-Carlo simulation.展开更多
The mechanism of the human auditory system in detecting sound signals with complex time frequency charcteristics in a white noise background was reviewed and discussed.The efficiency of such auditory detection was ass...The mechanism of the human auditory system in detecting sound signals with complex time frequency charcteristics in a white noise background was reviewed and discussed.The efficiency of such auditory detection was assessed by comparing it with that of parallel visual detection of the output of an analogous model displayed on the oscilloscope screen. The results suggest that the detection model of the human auditory system is quite similar to a tone correlator when the time frequency characteristics of the signal are known and to an energy detector when the signal is unknown. The relationship between the threshold signal to noise ratio and the signal duration is derived for different time frequency characteristics.展开更多
This paper describes an identification system for Chinese Materia Medicas （CMMs） in microscopic powder images. The imaging processing of the microscopic powder image is very complex because of the low contrast, blur...This paper describes an identification system for Chinese Materia Medicas （CMMs） in microscopic powder images. The imaging processing of the microscopic powder image is very complex because of the low contrast, blurry boundaries, overlapping objects, and messy background. Therefore, the object detection must segment the significant microscopic structures from the complex image. The objects are detected in these images using an adaptable interactive method. After identifying the significant microscopic structures, the system identifies 14 features belonging to three main characteristics. These features form a 14-dimensional vector that represents the microscopic structures. The multi-dimensional vector is then analyzed using a feature assignment algorithm that picks the most notable features to construct a decision tree with thresholds. The identification system consists of a coarse classifier based on the decision tree and a fine classifier using similarity measurements to rank the possible results. Tests on 528 images from 24 different kinds of microscopic structures show the system effectiveness and applicability.展开更多
This paper presents the nonlinear electromagneto-mechanical behavior of magnetostrictive/piezoelectric laminates under three-point bending both numerically and experimentally.The laminates are fabricated using thin Te...This paper presents the nonlinear electromagneto-mechanical behavior of magnetostrictive/piezoelectric laminates under three-point bending both numerically and experimentally.The laminates are fabricated using thin Terfenol-D and PZT layers.The three-point bending test was conducted on the Terfenol-D/PZT laminates,and the displacement,induced magnetic field and induced voltage due to mechanical loads were measured.Three-dimensional finite element analysis was also carried out,and the electromagneto-mechanical fields in the laminates were predicted by introducing a second-order magnetoelastic constant for Terfenol-D.Comparison was then made between simulation and experiment.展开更多
文摘In practical communication and radar systems, the phase of the received signal is random, the arrival time is unknown, the lasting time is limited and the SNR is often very low. In order to realize the detection of the signal, the method of using a group of nonlinear differential equations is presented. The theory of this chaos-based detection is analyzed. Computer simulation indicates that the shortest lasting time of the transient signal that can be detected out is 12 periods, the detection error of arrival time is less than 7/8 signal＇ s period, the detection characteristics are got using Monte-Carlo simulation.
文摘The mechanism of the human auditory system in detecting sound signals with complex time frequency charcteristics in a white noise background was reviewed and discussed.The efficiency of such auditory detection was assessed by comparing it with that of parallel visual detection of the output of an analogous model displayed on the oscilloscope screen. The results suggest that the detection model of the human auditory system is quite similar to a tone correlator when the time frequency characteristics of the signal are known and to an energy detector when the signal is unknown. The relationship between the threshold signal to noise ratio and the signal duration is derived for different time frequency characteristics.
文摘This paper describes an identification system for Chinese Materia Medicas （CMMs） in microscopic powder images. The imaging processing of the microscopic powder image is very complex because of the low contrast, blurry boundaries, overlapping objects, and messy background. Therefore, the object detection must segment the significant microscopic structures from the complex image. The objects are detected in these images using an adaptable interactive method. After identifying the significant microscopic structures, the system identifies 14 features belonging to three main characteristics. These features form a 14-dimensional vector that represents the microscopic structures. The multi-dimensional vector is then analyzed using a feature assignment algorithm that picks the most notable features to construct a decision tree with thresholds. The identification system consists of a coarse classifier based on the decision tree and a fine classifier using similarity measurements to rank the possible results. Tests on 528 images from 24 different kinds of microscopic structures show the system effectiveness and applicability.
基金supported by Grant-in-Aid for JSPS Fellows(22·3402).
文摘This paper presents the nonlinear electromagneto-mechanical behavior of magnetostrictive/piezoelectric laminates under three-point bending both numerically and experimentally.The laminates are fabricated using thin Terfenol-D and PZT layers.The three-point bending test was conducted on the Terfenol-D/PZT laminates,and the displacement,induced magnetic field and induced voltage due to mechanical loads were measured.Three-dimensional finite element analysis was also carried out,and the electromagneto-mechanical fields in the laminates were predicted by introducing a second-order magnetoelastic constant for Terfenol-D.Comparison was then made between simulation and experiment.
