Direct sequence spread spectrum transmission can be realized at low SNR, and has low probabilityof detection. It is aly problem how to obtain the original users＇ signal in a non-cooperative context. In practicality, ...Direct sequence spread spectrum transmission can be realized at low SNR, and has low probabilityof detection. It is aly problem how to obtain the original users＇ signal in a non-cooperative context. In practicality, the DS/CDMA sources received are linear convolute mixing. A more complex multichannel blind deconvolution MBD algorithm is required to achieve better source separation. An improved MBD algorithm for separating linear convolved mixtures of signals in CDMA system is proposed. This algorithm is based on minimizing the average squared cross-output-channel-correlation. The mixture coefficients are totally unknown, while some knowledge about temporal model exists. Results show that the proposed algorithm can bring about the exactness and low computational complexity.展开更多
To achieve accurate classification and recognition of ship target types,it is necessary to establish a sample library of ship targets to be identified.On the basis of exploring the principles of building a ship target...To achieve accurate classification and recognition of ship target types,it is necessary to establish a sample library of ship targets to be identified.On the basis of exploring the principles of building a ship target image library,the paper determines the sample set.Using 3DS MAX software as the platform,combined with the accurate 3D model of the ship in an offline state,the software fully utilizes its own rendering and animation functions to achieve the automatic generation of multi-view and multi-scale views of ship targets.To reduce the storage capacity of the image database,a construction method of the ship target image database based on the AP algorithm is presented.The algorithm can obtain the optimal cluster number,reduce the data storage capacity of the image database,and save the calculation amount for the subsequent matching calculation.展开更多
发现服务(discovery service,DS)通过提供一种查询服务,为用户提供物品射频识别(radio frequency identification,RFID)标志与供应链中存储该物品信息的多个信息服务器地址之间的映射服务,以帮助用户获取物品在整个供应链中的信息。但是...发现服务(discovery service,DS)通过提供一种查询服务,为用户提供物品射频识别(radio frequency identification,RFID)标志与供应链中存储该物品信息的多个信息服务器地址之间的映射服务,以帮助用户获取物品在整个供应链中的信息。但是,当前已有的DS设计方案不能满足兼容不同的RFID编码标准、高效的系统性能和强大的抵御拒绝服务(denial of service,Do S)攻击能力等需求。因此,针对已有DS研究的不足,基于结构化对等(peer-to-peer,P2P)网络和PCache主动缓存算法提出一种称为PCache DS的DS设计方案。仿真实验的结果表明,与已有的DS研究相比,PCache DS不仅能够兼容不同的RFID编码标准,而且具有更低的平均查询时延、更强的系统处理性能和抵御Do S攻击能力,能够更好地满足DS的应用需求。展开更多
基金the National Natural Science Foundation of China (60472052,10577007)the Specialized Research Fund for National Key Lab of Communication (51434020105ZS04).
文摘Direct sequence spread spectrum transmission can be realized at low SNR, and has low probabilityof detection. It is aly problem how to obtain the original users＇ signal in a non-cooperative context. In practicality, the DS/CDMA sources received are linear convolute mixing. A more complex multichannel blind deconvolution MBD algorithm is required to achieve better source separation. An improved MBD algorithm for separating linear convolved mixtures of signals in CDMA system is proposed. This algorithm is based on minimizing the average squared cross-output-channel-correlation. The mixture coefficients are totally unknown, while some knowledge about temporal model exists. Results show that the proposed algorithm can bring about the exactness and low computational complexity.
文摘To achieve accurate classification and recognition of ship target types,it is necessary to establish a sample library of ship targets to be identified.On the basis of exploring the principles of building a ship target image library,the paper determines the sample set.Using 3DS MAX software as the platform,combined with the accurate 3D model of the ship in an offline state,the software fully utilizes its own rendering and animation functions to achieve the automatic generation of multi-view and multi-scale views of ship targets.To reduce the storage capacity of the image database,a construction method of the ship target image database based on the AP algorithm is presented.The algorithm can obtain the optimal cluster number,reduce the data storage capacity of the image database,and save the calculation amount for the subsequent matching calculation.
文摘发现服务(discovery service,DS)通过提供一种查询服务,为用户提供物品射频识别(radio frequency identification,RFID)标志与供应链中存储该物品信息的多个信息服务器地址之间的映射服务,以帮助用户获取物品在整个供应链中的信息。但是,当前已有的DS设计方案不能满足兼容不同的RFID编码标准、高效的系统性能和强大的抵御拒绝服务(denial of service,Do S)攻击能力等需求。因此,针对已有DS研究的不足,基于结构化对等(peer-to-peer,P2P)网络和PCache主动缓存算法提出一种称为PCache DS的DS设计方案。仿真实验的结果表明,与已有的DS研究相比,PCache DS不仅能够兼容不同的RFID编码标准,而且具有更低的平均查询时延、更强的系统处理性能和抵御Do S攻击能力,能够更好地满足DS的应用需求。
