The improvements of anti-jamming performance of modern radar seeker are great threats to military targets. To protect the target from detection and estimation, the novel signal-to-interference-plus-noise ratio(SINR)-b...The improvements of anti-jamming performance of modern radar seeker are great threats to military targets. To protect the target from detection and estimation, the novel signal-to-interference-plus-noise ratio(SINR)-based and mutual information(MI)-based jamming design techniques were proposed. To interfere with the target detection, the jamming was designed to minimize the SINR of the radar seeker. To impair the estimation performance, the mutual information between the radar echo and the random target impulse response was used as the criterion. The spectral of optimal jamming under the two criteria were achieved with the power constraints. Simulation results show the effectiveness of the jamming techniques. SINR and MI of the SINR-based jamming, the MI-based jamming as well as the predefined jamming under the same power constraints were compared. Furthermore, the probability of detection and minimum mean-square error(MMSE) were also utilized to validate the jamming performance. Under the jamming power constraint of 1 W, the relative decrease of the probability of detection using SINR-based optimal jamming is about 47%, and the relative increase of MMSE using MI-based optimal jamming is about 8%. Besides, two useful jamming design principles are concluded which can be used in limited jamming power situations.展开更多
This paper applies the Seismic Hazard Analysis method for the cities of China to research on the probability of earthquake occurrence in the Daduhe drainage area,where the cascade dam system is located.This research i...This paper applies the Seismic Hazard Analysis method for the cities of China to research on the probability of earthquake occurrence in the Daduhe drainage area,where the cascade dam system is located.This research is based on the potential seismic source scheme of the Seismic Ground Motion Parameter Zonation Map of China(2001),and uses Poisson distribution as an earthquake occurrence model.Earthquake magnitude obeys truncated exponential distribution.The spatial distribution function of the potential seismic source zone is taken as the first-class spatial probability distribution,and the homogeneous probability distribution in the potential seismic source zone as the second-class spatial probability distribution.Considering the seismic intensity attenuation relationship of western China,we compute the occurrence probability of an earthquake around magnitude 6.0(5.5～6.5),7.0(6.5～7.5)and over 7.5 in the Daduhe drainage area,where 22 series cascade dams will be built.The results can be used for hydropower plant planning,hydropower dam site selection and seismic fortification.展开更多
In this paper, we have formulated a strategy that the limited available codesequences in pure Direct-Sequence (DS) or Frequency-Hopping (FH) system can be reused to realizedense optical CDMA: the strategy of novel hyb...In this paper, we have formulated a strategy that the limited available codesequences in pure Direct-Sequence (DS) or Frequency-Hopping (FH) system can be reused to realizedense optical CDMA: the strategy of novel hybrid DS/FH system. In which, the case that there are nusers employing the same FH pattern but different DS code patterns is considered. On the conditionthat the impact of channel noises is neglected, the upper bound probability of error is evaluatedbased on the stationary random process theory. The results shout that the hybrid system is suitablefor Dense Optical CDMA (DOCDMA) communication. Moreover, the problems such as the link-impairment,dispersion of group velocity, etc. in the pure (DS or FH) system can be solved effectively.展开更多
基金Project(61171133)supported by the National Natural Science Foundation of ChinaProject(11JJ1010)supported by the Natural Science Fund for Distinguished Young Scholars of Hunan Province,China
文摘The improvements of anti-jamming performance of modern radar seeker are great threats to military targets. To protect the target from detection and estimation, the novel signal-to-interference-plus-noise ratio(SINR)-based and mutual information(MI)-based jamming design techniques were proposed. To interfere with the target detection, the jamming was designed to minimize the SINR of the radar seeker. To impair the estimation performance, the mutual information between the radar echo and the random target impulse response was used as the criterion. The spectral of optimal jamming under the two criteria were achieved with the power constraints. Simulation results show the effectiveness of the jamming techniques. SINR and MI of the SINR-based jamming, the MI-based jamming as well as the predefined jamming under the same power constraints were compared. Furthermore, the probability of detection and minimum mean-square error(MMSE) were also utilized to validate the jamming performance. Under the jamming power constraint of 1 W, the relative decrease of the probability of detection using SINR-based optimal jamming is about 47%, and the relative increase of MMSE using MI-based optimal jamming is about 8%. Besides, two useful jamming design principles are concluded which can be used in limited jamming power situations.
基金Ministry of Science and Technology specializeditem of social welfare (2005DIB3J119)Sub-topics of National Science and Technology Support Project(2006BAC13B01-0602,2006BAC13B02)
文摘This paper applies the Seismic Hazard Analysis method for the cities of China to research on the probability of earthquake occurrence in the Daduhe drainage area,where the cascade dam system is located.This research is based on the potential seismic source scheme of the Seismic Ground Motion Parameter Zonation Map of China(2001),and uses Poisson distribution as an earthquake occurrence model.Earthquake magnitude obeys truncated exponential distribution.The spatial distribution function of the potential seismic source zone is taken as the first-class spatial probability distribution,and the homogeneous probability distribution in the potential seismic source zone as the second-class spatial probability distribution.Considering the seismic intensity attenuation relationship of western China,we compute the occurrence probability of an earthquake around magnitude 6.0(5.5～6.5),7.0(6.5～7.5)and over 7.5 in the Daduhe drainage area,where 22 series cascade dams will be built.The results can be used for hydropower plant planning,hydropower dam site selection and seismic fortification.
文摘In this paper, we have formulated a strategy that the limited available codesequences in pure Direct-Sequence (DS) or Frequency-Hopping (FH) system can be reused to realizedense optical CDMA: the strategy of novel hybrid DS/FH system. In which, the case that there are nusers employing the same FH pattern but different DS code patterns is considered. On the conditionthat the impact of channel noises is neglected, the upper bound probability of error is evaluatedbased on the stationary random process theory. The results shout that the hybrid system is suitablefor Dense Optical CDMA (DOCDMA) communication. Moreover, the problems such as the link-impairment,dispersion of group velocity, etc. in the pure (DS or FH) system can be solved effectively.
基金Acknowledgements The authors would like to thank the anonymous referees for valuable comments and suggestions to improve the earlier version of this paper. This work was supported by the National Natural Science Foundation of China （Grant Nos. 11401436, 11226204, 11171164, 11271385）, the Doctoral Fund Program of Tianjin Normal University （Grant No. 52XB1204）, and the MOE Youth Project in Humanities and Social Sciences （NO. 14YJCZH048）.
