The exponential growth of the number of network devices in recent years not only entails the need for automation of management tasks,but also leads to the increase of available network data and metadata.5G and beyond ...The exponential growth of the number of network devices in recent years not only entails the need for automation of management tasks,but also leads to the increase of available network data and metadata.5G and beyond standards already cover those requirements and also include the need to define and use machine learning techniques to take advantage of the data acquired,especially using geolocated Call Detail Record(CDR)data sets.However,this scenario requires novel cellular network analysis methodologies to exploit all these available data,especially for the network usage pattern in order to ease the management tasks.In this work,a novel method based on information theory metrics like the Kullback-Leibler divergence and data classification algorithms is proposed to identify representative urban areas in terms of the network usage pattern.Methodology validation is performed via computer analysis using the Open Big Data CDR data set in the Milan area for different scenarios.Obtained results validate the proposed methodology and also reveal its adaptability in terms of specific scenario characteristics.Network usage patterns are calculated for each representative area,paving the path to several future research lines in network management,such as network usage prediction based on this methodology and using the comportment time series.展开更多
Mobile ad hoc networks are particularly vulnerable to denial of service （DOS） attacks launched through compromised nodes or intruders. In this paper, we present a new DOS attack and its defense in ad hoc networks. T...Mobile ad hoc networks are particularly vulnerable to denial of service （DOS） attacks launched through compromised nodes or intruders. In this paper, we present a new DOS attack and its defense in ad hoc networks. The new DOS attack, called AA hoc Flooding Attack（AHFA）, is that intruder broadcasts mass Route Request packets to exhaust the communication bandwidth and node resource so that the valid communication can not be kept. After analyzed AM hoc Flooding Attack, we develop Flooding Attack Prevention （FAP）, a genetic defense against the AM hoc Flooding Attack. When the intruder broadcasts exceeding packets of Route Request, the immediate neighbors of the intruder record the rate of Route Request. Once the threshold is exceeded, nodes deny any future request packets from the intruder. The results of our implementation show FAP can prevent the AM hoe Flooding attack efficiently.展开更多
Group key distribution is faced with two important problems, i.e. reliability and scalability, to support security multicast for large and dynamic groups. With group member increasing, traditional reliable multicast p...Group key distribution is faced with two important problems, i.e. reliability and scalability, to support security multicast for large and dynamic groups. With group member increasing, traditional reliable multicast protocol can not deal with them fully. Gossip-based group key distribution idea for wide-area dissemination was provided. It is based on an gossip-based loss recovery control mechanism. It can provide a probabilistic reliable guarantee for a information dissemination to reach every group member, which can achieve scalability and reliability. To achieve full reliability, three layers protocol model in group key distribution was provided. One is best effect layer, which provides unreliable dissemination. Other is gossip-based loss recovery layer, which provides probabilistic reliable guarantee. Last is vsync-based layer, which provide deterministic loss recovery. We integrate probabilistic loss recovery method with deterministic one. The model possess scalability that probabilistic method has and full reliability prosthesis by vsync-based. To evaluate the effectiveness of gossip technique in scalable and reliable multicast protocols. We have compared gossip protocol with other reliable multicast protocols. Experimental result shows that gossip protocol has better scalability than other.展开更多
The paper considers three common snubber circuits used on gate turn-off thyristor and/or insulated gate bipolar transistor inverters. The three snubbers are passive lossless circuits for power bridge legs, and the imp...The paper considers three common snubber circuits used on gate turn-off thyristor and/or insulated gate bipolar transistor inverters. The three snubbers are passive lossless circuits for power bridge legs, and the improvements and modifications to these snubber circuits are presented. The comparative features and operation of the three improved energy recovery snubbers are discussed and supported by PSPICE simulations and experimental results.展开更多
Dynamic time warping(DTW)spends most of the time in generating the correlation table,and it establishes the global path constraints to reduce the time complexity.However,the global constraints restrain just in terms o...Dynamic time warping(DTW)spends most of the time in generating the correlation table,and it establishes the global path constraints to reduce the time complexity.However,the global constraints restrain just in terms of the time axis.In this paper,we therefore propose another version of DTW,to be called branch-and-bound DTW(BnB-DTW),which adaptively controb its global path constraints by reflecting the contents of input patterns. Experimental results show that the suggested BnB-DTW algorithm performs more efficiently than other conventional DTW approaches while not increasing the optimal warping cost.展开更多
The paper presents a complete composite gate turn-off thyristor (GTO) model, which is based on the combination of the p-n-p and n-p-n transistor models. PSpice simulations and parametric sensitive analysis are perform...The paper presents a complete composite gate turn-off thyristor (GTO) model, which is based on the combination of the p-n-p and n-p-n transistor models. PSpice simulations and parametric sensitive analysis are performed with the complete composite model and calculated results are given, which show that it corresponds statically and dynamically with the practical device. In particular, the GTO gate dynamical characteristics in practical circuits are discussed and experimental results are included.展开更多
基金partially supported by the grant TED2021131699B-I00/AEI/10.13039/501100011033/European Union Next Generation EU/PRTRthe Spanish Ministry of Science and Innovation,grants PID2020-112545RB-C54 and PDC2022-133900-I00the Univ.Rey Juan Carlos Program for Research Promotion and Development(Ref.F799 and F920)。
文摘The exponential growth of the number of network devices in recent years not only entails the need for automation of management tasks,but also leads to the increase of available network data and metadata.5G and beyond standards already cover those requirements and also include the need to define and use machine learning techniques to take advantage of the data acquired,especially using geolocated Call Detail Record(CDR)data sets.However,this scenario requires novel cellular network analysis methodologies to exploit all these available data,especially for the network usage pattern in order to ease the management tasks.In this work,a novel method based on information theory metrics like the Kullback-Leibler divergence and data classification algorithms is proposed to identify representative urban areas in terms of the network usage pattern.Methodology validation is performed via computer analysis using the Open Big Data CDR data set in the Milan area for different scenarios.Obtained results validate the proposed methodology and also reveal its adaptability in terms of specific scenario characteristics.Network usage patterns are calculated for each representative area,paving the path to several future research lines in network management,such as network usage prediction based on this methodology and using the comportment time series.
基金This project was supported by the National"863"High Technology Development Programof China (2003AA148010) Key Technologies R&D Programof China (2002DA103A03 -07)
文摘Mobile ad hoc networks are particularly vulnerable to denial of service （DOS） attacks launched through compromised nodes or intruders. In this paper, we present a new DOS attack and its defense in ad hoc networks. The new DOS attack, called AA hoc Flooding Attack（AHFA）, is that intruder broadcasts mass Route Request packets to exhaust the communication bandwidth and node resource so that the valid communication can not be kept. After analyzed AM hoc Flooding Attack, we develop Flooding Attack Prevention （FAP）, a genetic defense against the AM hoc Flooding Attack. When the intruder broadcasts exceeding packets of Route Request, the immediate neighbors of the intruder record the rate of Route Request. Once the threshold is exceeded, nodes deny any future request packets from the intruder. The results of our implementation show FAP can prevent the AM hoe Flooding attack efficiently.
文摘Group key distribution is faced with two important problems, i.e. reliability and scalability, to support security multicast for large and dynamic groups. With group member increasing, traditional reliable multicast protocol can not deal with them fully. Gossip-based group key distribution idea for wide-area dissemination was provided. It is based on an gossip-based loss recovery control mechanism. It can provide a probabilistic reliable guarantee for a information dissemination to reach every group member, which can achieve scalability and reliability. To achieve full reliability, three layers protocol model in group key distribution was provided. One is best effect layer, which provides unreliable dissemination. Other is gossip-based loss recovery layer, which provides probabilistic reliable guarantee. Last is vsync-based layer, which provide deterministic loss recovery. We integrate probabilistic loss recovery method with deterministic one. The model possess scalability that probabilistic method has and full reliability prosthesis by vsync-based. To evaluate the effectiveness of gossip technique in scalable and reliable multicast protocols. We have compared gossip protocol with other reliable multicast protocols. Experimental result shows that gossip protocol has better scalability than other.
基金Supported by the Zhejiang Province Nature Science Foundation of Chinathe Royal Society of U.K.
文摘The paper considers three common snubber circuits used on gate turn-off thyristor and/or insulated gate bipolar transistor inverters. The three snubbers are passive lossless circuits for power bridge legs, and the improvements and modifications to these snubber circuits are presented. The comparative features and operation of the three improved energy recovery snubbers are discussed and supported by PSPICE simulations and experimental results.
文摘Dynamic time warping(DTW)spends most of the time in generating the correlation table,and it establishes the global path constraints to reduce the time complexity.However,the global constraints restrain just in terms of the time axis.In this paper,we therefore propose another version of DTW,to be called branch-and-bound DTW(BnB-DTW),which adaptively controb its global path constraints by reflecting the contents of input patterns. Experimental results show that the suggested BnB-DTW algorithm performs more efficiently than other conventional DTW approaches while not increasing the optimal warping cost.
基金Supported by the Return Overseas Scholar Foundation of the State Education Commission
文摘The paper presents a complete composite gate turn-off thyristor (GTO) model, which is based on the combination of the p-n-p and n-p-n transistor models. PSpice simulations and parametric sensitive analysis are performed with the complete composite model and calculated results are given, which show that it corresponds statically and dynamically with the practical device. In particular, the GTO gate dynamical characteristics in practical circuits are discussed and experimental results are included.
