Abstract： This paper focuses on the first-or- der and second-order performance of dual-hop underlay cognitive radio systems with oppor- tunistic relaying （UCR-OR） over indepen- dent and non-identically distributed ...Abstract： This paper focuses on the first-or- der and second-order performance of dual-hop underlay cognitive radio systems with oppor- tunistic relaying （UCR-OR） over indepen- dent and non-identically distributed （i.ni.d） Rayleigh fading channels. For the UCR-OR systems, the tolerable maximum interference power （TMIP） Q at primary users （PUs） and the allowable maximum transmission power limit （AMTP） P at secondary users （SUs） are considered, simultaneously. We first obtain the closed-form solutions to the first-order performance such as outage probability, ave- rage symbol error ratio （SER）, and ergodic capacity （EC）. Secondly, we investigate the second-order statistical performance, i.e., ave- rage outage rate （AOR） and average outage duration （AOD）. With the consideration that in practice implementation the receiver perfor- mance is primarily influenced by the signal- to-noise ratio （SNR） （not the signal envelope）, the second-order statistical performance is investigated based on the equivalent instan- taneous end-to-end SNR. Finally, we present the detailed performance comparison analysis of UCR-OR systems by defining a random variable ,μ=Pmax/Q. The results show that the effect of μ on the first-order and second-or- der performances is different greatly. For the first-order performance, the perlbrmance gap is negligible when the value of// is relatively large. However, for the second-order one, the gap is distinct.展开更多
We study the statistics of the emitted filed from Rydberg atom confined inside a microcavity and interacting with a pump laser in the strong coupling regime. We explore the manifestation of the antibunching in connect...We study the statistics of the emitted filed from Rydberg atom confined inside a microcavity and interacting with a pump laser in the strong coupling regime. We explore the manifestation of the antibunching in connection with the internal system parameters.展开更多
Based on statistical damage mechanics,the constitutive model of a rock underthree-dimensional stress was established by the law that the statistical strength of rockmicro-element obeys Weibull distribution.The acousti...Based on statistical damage mechanics,the constitutive model of a rock underthree-dimensional stress was established by the law that the statistical strength of rockmicro-element obeys Weibull distribution.The acoustic emission (AE) evolution model ofrock failure was put forward according to the view that rock damage and AE were consistent.Moreover,in the failure process of rock under three-dimensional stress,the change inrelationship between stress condition parameter and the characteristic parameters of AE,such as the event number and its change rate,were studied.Also,the rock AE characteristicunder uniaxial compression was analyzed in theory and verified with examples.Theresults indicate that the cumulative event number and change rate of AE in rock failure aredetermined by stress state parameter F.Along with the gradual increase of F,first the cumulativeevent number increases gradually,then rapidly,and then slowly after the stresspeak.The form of change rate of an event by increasing F is consistent with the distributionform of rock micro-element strength.The model explained the phenomenon that a relativelyquiet period of AE appears before rock rupture that is observed by many researchersin experiments.Verification examples indicate that the AE evolution model is consistentwith the test results,so the model is reasonable and correct.展开更多
The hazard caused by the fragments of damaged structures is usually significant in acci-dental explosions or hostile blast events.A reliable and efficient method to estimate probable fragment size,velocity and launch ...The hazard caused by the fragments of damaged structures is usually significant in acci-dental explosions or hostile blast events.A reliable and efficient method to estimate probable fragment size,velocity and launch distance will be useful to assess and design countermeasures to mitigate the possible fragment hazards.This paper presents a numerical method for predicting the size and launch distance of the fragments caused by explosive damage of masonry wall.Numerical simulations with different scaled distances are carried out,and the statistical distribution functions of the fragment size and launch distance in terms of the scaled distance are derived.展开更多
基金supported by the Natural ScienceFoundation of China under Grant 61261015the 973 project 2013CB329104+3 种基金the Natural Science Foundation of China under Grant61372124,61363059,and 61302100the projects BK2011027the Natural Science Foundation of Gansu Province for Distinguished Young Scholars(1308RJDA007)the Foundation Research Funds for the University of Gansu Province:'Massive MIMO channels modeling and estimation over millimeter wave band for 5G'
文摘Abstract： This paper focuses on the first-or- der and second-order performance of dual-hop underlay cognitive radio systems with oppor- tunistic relaying （UCR-OR） over indepen- dent and non-identically distributed （i.ni.d） Rayleigh fading channels. For the UCR-OR systems, the tolerable maximum interference power （TMIP） Q at primary users （PUs） and the allowable maximum transmission power limit （AMTP） P at secondary users （SUs） are considered, simultaneously. We first obtain the closed-form solutions to the first-order performance such as outage probability, ave- rage symbol error ratio （SER）, and ergodic capacity （EC）. Secondly, we investigate the second-order statistical performance, i.e., ave- rage outage rate （AOR） and average outage duration （AOD）. With the consideration that in practice implementation the receiver perfor- mance is primarily influenced by the signal- to-noise ratio （SNR） （not the signal envelope）, the second-order statistical performance is investigated based on the equivalent instan- taneous end-to-end SNR. Finally, we present the detailed performance comparison analysis of UCR-OR systems by defining a random variable ,μ=Pmax/Q. The results show that the effect of μ on the first-order and second-or- der performances is different greatly. For the first-order performance, the perlbrmance gap is negligible when the value of// is relatively large. However, for the second-order one, the gap is distinct.
文摘We study the statistics of the emitted filed from Rydberg atom confined inside a microcavity and interacting with a pump laser in the strong coupling regime. We explore the manifestation of the antibunching in connection with the internal system parameters.
基金Supported by the Key Program of National Basic Research Program(973)of China(2005CB221505)the National Natural Science Foundation of China(2005E041503)
文摘Based on statistical damage mechanics,the constitutive model of a rock underthree-dimensional stress was established by the law that the statistical strength of rockmicro-element obeys Weibull distribution.The acoustic emission (AE) evolution model ofrock failure was put forward according to the view that rock damage and AE were consistent.Moreover,in the failure process of rock under three-dimensional stress,the change inrelationship between stress condition parameter and the characteristic parameters of AE,such as the event number and its change rate,were studied.Also,the rock AE characteristicunder uniaxial compression was analyzed in theory and verified with examples.Theresults indicate that the cumulative event number and change rate of AE in rock failure aredetermined by stress state parameter F.Along with the gradual increase of F,first the cumulativeevent number increases gradually,then rapidly,and then slowly after the stresspeak.The form of change rate of an event by increasing F is consistent with the distributionform of rock micro-element strength.The model explained the phenomenon that a relativelyquiet period of AE appears before rock rupture that is observed by many researchersin experiments.Verification examples indicate that the AE evolution model is consistentwith the test results,so the model is reasonable and correct.
基金Supported by the Australian Research Council (ARC,No.DP0774061)National Natural Science Foundation of China (No.50638030 and 50528808).
文摘The hazard caused by the fragments of damaged structures is usually significant in acci-dental explosions or hostile blast events.A reliable and efficient method to estimate probable fragment size,velocity and launch distance will be useful to assess and design countermeasures to mitigate the possible fragment hazards.This paper presents a numerical method for predicting the size and launch distance of the fragments caused by explosive damage of masonry wall.Numerical simulations with different scaled distances are carried out,and the statistical distribution functions of the fragment size and launch distance in terms of the scaled distance are derived.
