An optimal design approach of high order FIR digital filter is developed based on the algorithm of neural networks with cosine basis function . The main idea is to minimize the sum of the square errors between the amp...An optimal design approach of high order FIR digital filter is developed based on the algorithm of neural networks with cosine basis function . The main idea is to minimize the sum of the square errors between the amplitude response of the desired FIR filter and that of the designed by training the weights of neural networks, then obtains the impulse response of FIR digital filter . The convergence theorem of the neural networks algorithm is presented and proved, and the optimal design method is introduced by designing four kinds of FIR digital filters , i.e., low-pass, high-pass, bandpass , and band-stop FIR digital filter. The results of the amplitude responses show that attenuation in stop-bands is more than 60 dB with no ripple and pulse existing in pass-bands, and cutoff frequency of passband and stop-band is easily controlled precisely .The presented optimal design approach of high order FIR digital filter is significantly effective.展开更多
Network economy had changed manufacturing environme nt at all. Open global market offer more choice to customer, and it become changea ble and unpredictable as consumers’ needs become more and more characteristic an ...Network economy had changed manufacturing environme nt at all. Open global market offer more choice to customer, and it become changea ble and unpredictable as consumers’ needs become more and more characteristic an d diversified. Various new technology coming forth and application accelerate th e rapid change of the market. The manufacturing enterprises were compelled t o change their strategy by the variability of the market, and time has been put to the all-important place. There is a need driven by the market to set up a ne twork design and manufacturing mode which have rapid market responsiveness. In order to meet the need for network manufacturing, the organization and manage ment of manufacturing enterprise need a completely innovation, next generation o f manufacturing system must have the character such as digitization, flexibility , agility, customization and globalization and so on. As for an enterprise in au to industry, how to gather together the orders through the distribution, and rap id produce the product which can meet the customer’s need, it is the key that th e contemporary enterprises succeed in the competitive market. The competitive market requires rapid product development. Close cooperation amo ng the designers will accelerate the product development by shortening the devel opment cycle, improving the product quality and reducing the investment. It has been emphasized in the methodology of concurrent engineering (CE). But sometimes those partners are distributed in the world, so there is a need for an importan t technology contribution to collaborative engineering, and supporting distribut ed designers for rapid product development. This paper focuses on a collaborative design system: Product Digit Collaborative Design System (PDCDS). The solution of PDCDS can make it more efficient and rel iable to visit teledata as well as we can get it from local database. It will be ease to get the newest design process information aided by PDCDS, and it will h ave higher efficiency by collaborative work. Comparing with other traditional Pr oduct Data Management (PDM) software system, PDCDS have some new characters such as group, dynamicness, synchronization or asynchronism working mode, and the hi story recorder is needed, and it also surport Webservice.展开更多
The architecture of digital sheet metal manufacturing system is proposed based on the classification of sheet metal manufacturing information.The essence of digital manufacturing is the definition,management and trans...The architecture of digital sheet metal manufacturing system is proposed based on the classification of sheet metal manufacturing information.The essence of digital manufacturing is the definition,management and transfer of information,and the key technologies are brought forward and described.It is pointed out that knowledge-based manufacturing elements design is necessary to make digital technology efficient.The management of all kinds of sheet metal manufacturing element information is to build single source of manufacturing data.Multi-state model-based digital transfer and coordination method is designed to provide a foundation for digital manufacturing of aircraft sheet metal part.The application of digital sheet metal manufacturing is exemplified with an aircraft sheet metal part.The application result is compared to that of the traditional analog transfer technology.It is shown that the developed technology can improve part quality,shorten manufacturing time and lower manufacturing cost.展开更多
This work provides a method to predict the three-dimensional equivalent elastic properties of the filament-wound composites based on the multi-scale homogenization principle.In the meso-scale,a representative volume e...This work provides a method to predict the three-dimensional equivalent elastic properties of the filament-wound composites based on the multi-scale homogenization principle.In the meso-scale,a representative volume element(RVE)is defined and the bridging model is adopted to establish a theoretical predictive model for its three-dimensional equivalent elastic constants.The results obtained through this method for the previous experimental model are compared with the ones gained respectively by experiments and classical laminate theory to verify the reliability of this model.In addition,the effects of some winding parameters,such as winding angle,on the equivalent elastic behavior of the filament-wound composites are analyzed.The rules gained can provide a theoretical reference for the optimum design of filament-wound composites.展开更多
Three-dimensional(3D) synthetic aperture radar(SAR)extends the conventional 2D images into 3D features by several acquisitions in different aspects. Compared with 3D techniques via multiple observations in elevation, ...Three-dimensional(3D) synthetic aperture radar(SAR)extends the conventional 2D images into 3D features by several acquisitions in different aspects. Compared with 3D techniques via multiple observations in elevation, e.g. SAR interferometry(InSAR) and SAR tomography(TomoSAR), holographic SAR can retrieve 3D structure by observations in azimuth. This paper focuses on designing a novel type of orbit to achieve SAR regional all-azimuth observation(AAO) for embedded targets detection and holographic 3D reconstruction. The ground tracks of the AAO orbit separate the earth surface into grids. Target in these grids can be accessed with an azimuth angle span of360°, which is similar to the flight path of airborne circular SAR(CSAR). Inspired from the successive coverage orbits of optical sensors, several optimizations are made in the proposed method to ensure favorable grazing angles, the performance of 3D reconstruction, and long-term supervision for SAR sensors. Simulation experiments show the regional AAO can be completed within five hours. In addition, a second AAO of the same area can be duplicated in two days. Finally, an airborne SAR data process result is presented to illustrate the significance of AAO in 3D reconstruction.展开更多
基金This project was supported by the National Natural Science Foundation of China (50277010)Doctoral Special Fund of Ministry of Education (20020532016) and Fund of Outstanding Young Scientist of Hunan University.
文摘An optimal design approach of high order FIR digital filter is developed based on the algorithm of neural networks with cosine basis function . The main idea is to minimize the sum of the square errors between the amplitude response of the desired FIR filter and that of the designed by training the weights of neural networks, then obtains the impulse response of FIR digital filter . The convergence theorem of the neural networks algorithm is presented and proved, and the optimal design method is introduced by designing four kinds of FIR digital filters , i.e., low-pass, high-pass, bandpass , and band-stop FIR digital filter. The results of the amplitude responses show that attenuation in stop-bands is more than 60 dB with no ripple and pulse existing in pass-bands, and cutoff frequency of passband and stop-band is easily controlled precisely .The presented optimal design approach of high order FIR digital filter is significantly effective.
文摘Network economy had changed manufacturing environme nt at all. Open global market offer more choice to customer, and it become changea ble and unpredictable as consumers’ needs become more and more characteristic an d diversified. Various new technology coming forth and application accelerate th e rapid change of the market. The manufacturing enterprises were compelled t o change their strategy by the variability of the market, and time has been put to the all-important place. There is a need driven by the market to set up a ne twork design and manufacturing mode which have rapid market responsiveness. In order to meet the need for network manufacturing, the organization and manage ment of manufacturing enterprise need a completely innovation, next generation o f manufacturing system must have the character such as digitization, flexibility , agility, customization and globalization and so on. As for an enterprise in au to industry, how to gather together the orders through the distribution, and rap id produce the product which can meet the customer’s need, it is the key that th e contemporary enterprises succeed in the competitive market. The competitive market requires rapid product development. Close cooperation amo ng the designers will accelerate the product development by shortening the devel opment cycle, improving the product quality and reducing the investment. It has been emphasized in the methodology of concurrent engineering (CE). But sometimes those partners are distributed in the world, so there is a need for an importan t technology contribution to collaborative engineering, and supporting distribut ed designers for rapid product development. This paper focuses on a collaborative design system: Product Digit Collaborative Design System (PDCDS). The solution of PDCDS can make it more efficient and rel iable to visit teledata as well as we can get it from local database. It will be ease to get the newest design process information aided by PDCDS, and it will h ave higher efficiency by collaborative work. Comparing with other traditional Pr oduct Data Management (PDM) software system, PDCDS have some new characters such as group, dynamicness, synchronization or asynchronism working mode, and the hi story recorder is needed, and it also surport Webservice.
文摘The architecture of digital sheet metal manufacturing system is proposed based on the classification of sheet metal manufacturing information.The essence of digital manufacturing is the definition,management and transfer of information,and the key technologies are brought forward and described.It is pointed out that knowledge-based manufacturing elements design is necessary to make digital technology efficient.The management of all kinds of sheet metal manufacturing element information is to build single source of manufacturing data.Multi-state model-based digital transfer and coordination method is designed to provide a foundation for digital manufacturing of aircraft sheet metal part.The application of digital sheet metal manufacturing is exemplified with an aircraft sheet metal part.The application result is compared to that of the traditional analog transfer technology.It is shown that the developed technology can improve part quality,shorten manufacturing time and lower manufacturing cost.
文摘This work provides a method to predict the three-dimensional equivalent elastic properties of the filament-wound composites based on the multi-scale homogenization principle.In the meso-scale,a representative volume element(RVE)is defined and the bridging model is adopted to establish a theoretical predictive model for its three-dimensional equivalent elastic constants.The results obtained through this method for the previous experimental model are compared with the ones gained respectively by experiments and classical laminate theory to verify the reliability of this model.In addition,the effects of some winding parameters,such as winding angle,on the equivalent elastic behavior of the filament-wound composites are analyzed.The rules gained can provide a theoretical reference for the optimum design of filament-wound composites.
基金supported by the National Natural Science Foundation of China (62001436)the Natural Science Foundation of Jiangsu Province under (BK 20190143,JSGG20190823094603691)。
文摘Three-dimensional(3D) synthetic aperture radar(SAR)extends the conventional 2D images into 3D features by several acquisitions in different aspects. Compared with 3D techniques via multiple observations in elevation, e.g. SAR interferometry(InSAR) and SAR tomography(TomoSAR), holographic SAR can retrieve 3D structure by observations in azimuth. This paper focuses on designing a novel type of orbit to achieve SAR regional all-azimuth observation(AAO) for embedded targets detection and holographic 3D reconstruction. The ground tracks of the AAO orbit separate the earth surface into grids. Target in these grids can be accessed with an azimuth angle span of360°, which is similar to the flight path of airborne circular SAR(CSAR). Inspired from the successive coverage orbits of optical sensors, several optimizations are made in the proposed method to ensure favorable grazing angles, the performance of 3D reconstruction, and long-term supervision for SAR sensors. Simulation experiments show the regional AAO can be completed within five hours. In addition, a second AAO of the same area can be duplicated in two days. Finally, an airborne SAR data process result is presented to illustrate the significance of AAO in 3D reconstruction.
