摘要 :
With the development of artificial intelligence, Neural-Network based algorithms are widely applied in various fields, which causes the network structure more complex and the number of neurons also increases. Activation function i...
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With the development of artificial intelligence, Neural-Network based algorithms are widely applied in various fields, which causes the network structure more complex and the number of neurons also increases. Activation function is the most important part of the neuron, and has nonlinear characteristics. Therefore, the modeling of activation function on FPGA is faced with the problem of too many iterations and a large amount of hardware resource consumption. In this paper, a modeling method of Sigmoid function based on FPGA multi-processor is proposed. In this method, different processor cores are respectively used to control different modules, such as communication with peripherals, scheduling of computing resources, sharing of hardware resources, etc., so as to optimize the use of hardware resources and accelerate the computing. The result cased with the Sigmoid function shows that the method presented in this paper is feasible. And the comparison and analysis of the resources usages and simulation results are given.
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摘要 :
With the increase of the proportion of photovoltaic, wind power and other new energy generation in the power grid and the large amount of electric energy sent through DC transmission, the proportion of synchronous generators in th...
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With the increase of the proportion of photovoltaic, wind power and other new energy generation in the power grid and the large amount of electric energy sent through DC transmission, the proportion of synchronous generators in the power grid continues to decline, and more and more regional power grids have gradually become low inertia power systems. Aiming at the problems of poor controllability and low stability of grid connection of low inertia power system, a new method of grid connection between low inertia power system and main network is proposed. In this method, the grid connection composite device is applied to the grid connection of low inertia power system, so as to improve the grid connection speed of low inertia power system and realize grid connection, disconnection and tie-line power flow control of low inertia power system; in order to improve the stability of the frequency response process when the grid connected composite device is applied to the low inertia scenario, the virtual synchronous machine is introduced into the receiving converter to reduce the frequency offset peak and change rate of the low inertia power system in the grid connected regulation process. Through modeling and Simulation in PSCAD/ EMTDC, it is verified that the grid connection composite device based on virtual synchronous machine can greatly improve the controllability and stability of grid connection of low inertia power system.
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摘要 :
With the increase of the proportion of photovoltaic, wind power and other new energy generation in the power grid and the large amount of electric energy sent through DC transmission, the proportion of synchronous generators in th...
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With the increase of the proportion of photovoltaic, wind power and other new energy generation in the power grid and the large amount of electric energy sent through DC transmission, the proportion of synchronous generators in the power grid continues to decline, and more and more regional power grids have gradually become low inertia power systems. Aiming at the problems of poor controllability and low stability of grid connection of low inertia power system, a new method of grid connection between low inertia power system and main network is proposed. In this method, the grid connection composite device is applied to the grid connection of low inertia power system, so as to improve the grid connection speed of low inertia power system and realize grid connection, disconnection and tie-line power flow control of low inertia power system; in order to improve the stability of the frequency response process when the grid connected composite device is applied to the low inertia scenario, the virtual synchronous machine is introduced into the receiving converter to reduce the frequency offset peak and change rate of the low inertia power system in the grid connected regulation process. Through modeling and Simulation in PSCAD/ EMTDC, it is verified that the grid connection composite device based on virtual synchronous machine can greatly improve the controllability and stability of grid connection of low inertia power system.
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摘要 :
The autonomous planning and scheduling of the satellite is highly dependent on the accuracy of the on-board clock which, however, needs to be calibrated by the external information such as Global Navigation Satellite System (GNSS)...
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The autonomous planning and scheduling of the satellite is highly dependent on the accuracy of the on-board clock which, however, needs to be calibrated by the external information such as Global Navigation Satellite System (GNSS) or Ground time service system. To solve this problem, this paper proposes an autonomous on-board clock calibration method by observing the Lunar occultation. The steps of the time calibration are given. The crude time, firstly, is estimated by the combination of star trackers and sun sensors. Then the accurate time can be given by predicting and detecting the Lunar occultation. Meanwhile, the effects of the attitude sensor precision on the time calibration are studied. Finally, the validity of the on-board autonomous time calibration algorithm is verified by simulation.
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摘要 :
The autonomous planning and scheduling of the satellite is highly dependent on the accuracy of the on-board clock which, however, needs to be calibrated by the external information such as Global Navigation Satellite System (GNSS)...
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The autonomous planning and scheduling of the satellite is highly dependent on the accuracy of the on-board clock which, however, needs to be calibrated by the external information such as Global Navigation Satellite System (GNSS) or Ground time service system. To solve this problem, this paper proposes an autonomous on-board clock calibration method by observing the Lunar occultation. The steps of the time calibration are given. The crude time, firstly, is estimated by the combination of star trackers and sun sensors. Then the accurate time can be given by predicting and detecting the Lunar occultation. Meanwhile, the effects of the attitude sensor precision on the time calibration are studied. Finally, the validity of the on-board autonomous time calibration algorithm is verified by simulation.
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摘要 :
The power communication network has scale-free characteristic, which is prone to the occurrence of congestion at the hub nodes. The strategy to enhance the trafftc capacity and improve the transmission efftciency by appropriately ...
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The power communication network has scale-free characteristic, which is prone to the occurrence of congestion at the hub nodes. The strategy to enhance the trafftc capacity and improve the transmission efftciency by appropriately adding edges, which can reduce congestion. In the power communication network, the link addition strategy has a guiding effect on the new construction or reconstruction of the communication links, and does not need to consider the network connectivity. If the transmissionpath between two low-degree or low-betweenness nodes is far away and the load is heavy, the new link can balance network traffic and reduce congestion. However, if the nodes with shorter transmission distance and lighter load are added links, the improvement of transmission efftciency is small. Considering the high cost, the implementation of adding links is of little signiftcance. The same node avoidance mechanism is introduced. By constructing the set of linked nodes, which can record the adding links, to avoid the newly added links being too concentrated. A global effective link addition strategy based on the comprehensive index (CI) of the path length and the betweenness of nodes passing through is proposed, which is contribute to the design and optimization of realistic power communication networks. Network communication capacity can be estimated by critical packet generation rate Rc. The simulation results show that the proposed strategy can reduce the load of high-betweenness nodes, and balance network traffic, and increase the critical packet generation rate, and reduce the average transmission distance, and reduce congestion. When applying the proposed link addition strategy, it is necessary to analyze the actual topology of the power communication network in different regions, and consider various factors such as the cost of laying the communication link, the physical topology of the cable and the actual position of the communication nodes, and determine a reasonable edge-adding scheme.
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摘要 :
The power communication network has scale-free characteristic, which is prone to the occurrence of congestion at the hub nodes. The strategy to enhance the trafftc capacity and improve the transmission efftciency by appropriately ...
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The power communication network has scale-free characteristic, which is prone to the occurrence of congestion at the hub nodes. The strategy to enhance the trafftc capacity and improve the transmission efftciency by appropriately adding edges, which can reduce congestion. In the power communication network, the link addition strategy has a guiding effect on the new construction or reconstruction of the communication links, and does not need to consider the network connectivity. If the transmissionpath between two low-degree or low-betweenness nodes is far away and the load is heavy, the new link can balance network traffic and reduce congestion. However, if the nodes with shorter transmission distance and lighter load are added links, the improvement of transmission efftciency is small. Considering the high cost, the implementation of adding links is of little signiftcance. The same node avoidance mechanism is introduced. By constructing the set of linked nodes, which can record the adding links, to avoid the newly added links being too concentrated. A global effective link addition strategy based on the comprehensive index (CI) of the path length and the betweenness of nodes passing through is proposed, which is contribute to the design and optimization of realistic power communication networks. Network communication capacity can be estimated by critical packet generation rate Rc. The simulation results show that the proposed strategy can reduce the load of high-betweenness nodes, and balance network traffic, and increase the critical packet generation rate, and reduce the average transmission distance, and reduce congestion. When applying the proposed link addition strategy, it is necessary to analyze the actual topology of the power communication network in different regions, and consider various factors such as the cost of laying the communication link, the physical topology of the cable and the actual position of the communication nodes, and determine a reasonable edge-adding scheme.
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摘要 :
The power communication network has scale-free characteristic, which is prone to the occurrence of congestion at the hub nodes. The strategy to enhance the trafftc capacity and improve the transmission efftciency by appropriately ...
展开
The power communication network has scale-free characteristic, which is prone to the occurrence of congestion at the hub nodes. The strategy to enhance the trafftc capacity and improve the transmission efftciency by appropriately adding edges, which can reduce congestion. In the power communication network, the link addition strategy has a guiding effect on the new construction or reconstruction of the communication links, and does not need to consider the network connectivity. If the transmissionpath between two low-degree or low-betweenness nodes is far away and the load is heavy, the new link can balance network traffic and reduce congestion. However, if the nodes with shorter transmission distance and lighter load are added links, the improvement of transmission efftciency is small. Considering the high cost, the implementation of adding links is of little signiftcance. The same node avoidance mechanism is introduced. By constructing the set of linked nodes, which can record the adding links, to avoid the newly added links being too concentrated. A global effective link addition strategy based on the comprehensive index (CI) of the path length and the betweenness of nodes passing through is proposed, which is contribute to the design and optimization of realistic power communication networks. Network communication capacity can be estimated by critical packet generation rate Rc. The simulation results show that the proposed strategy can reduce the load of high-betweenness nodes, and balance network traffic, and increase the critical packet generation rate, and reduce the average transmission distance, and reduce congestion. When applying the proposed link addition strategy, it is necessary to analyze the actual topology of the power communication network in different regions, and consider various factors such as the cost of laying the communication link, the physical topology of the cable and the actual position of the communication nodes, and determine a reasona...
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