In this paper,the concept of computation diversity is proposed by employing generalized hybrid carrier(GHC)system.The signal is backed up by transform-domain computation to enhance the anti-fading capability.Theoretic...In this paper,the concept of computation diversity is proposed by employing generalized hybrid carrier(GHC)system.The signal is backed up by transform-domain computation to enhance the anti-fading capability.Theoretical analysis is presented to demonstrate the superiority of the proposed method.Numerical simulations in doubly-selective fading channels are provided to verify the results.The bit error rate(BER)performance is guaranteed with a small computational complexity increment.The proposed method not only extends the new diversity dimension,but also improves the diversity gain of the system without occupying additional wireless resources.Moreover,the proposed method shows good adaptability with single carrier modulation and improves diversity performance.As the simulation results shown,time-domain dual component computation diversity(TDC-CD)has 1d B BER gain and 0.1diversity gain at high signal-to-noise ratio,and single carrier system with TDC-CD achieves 2d B BER gain at 10~(-4).展开更多
The Himalayan orogen characterized by very high variability in tectonic and climatic processes,and is thus regarded as a natural laboratory for investigating the coupling of tectonics and climate,as well as the influe...The Himalayan orogen characterized by very high variability in tectonic and climatic processes,and is thus regarded as a natural laboratory for investigating the coupling of tectonics and climate,as well as the influence of this coupling on geomorphological processes.This study uses apatite fission track(AFT)dating of samples from a45-km-long section crossing the Great Himalaya Crystalline Complex(GHC)in the Nyalam area,southern Tibet,to constrain the timing and rate of late Cenozoic denudation.The AFT ages can be divided into two groups:(1)15–6 Ma,to the north of Nyalam town,for which the bestfit line of elevation-age has a gentle slope of 0.05,and for which a denudation rate of 0.27 mm/a is calculated;and(2)3–1 Ma,south of Nyalam town,for which the best-fit line has a steep slope of 0.64,and for which a denudation rate of 1.32 mm/a is calculated.The whole AFT ages has a positive correlation with sample elevation(i.e.,older ages are found at higher elevations),and the geographical location of the point of inflexion of the two fitted lines corresponds closely to the junction of Poqu River near Nyalam town.By integrating the AFT data with thermotectonic modeling,it can be inferred that the GHC has experienced two different periods of denudation:(1)slow denudation during middle to late Miocene(15–6 Ma)is recorded in the northern part of the GHC;and(2)rapid denudation from the Pliocene to the Pleistocene(3–1 Ma)is recorded in the southern part of the GHC.An abrupt change in denudation rate occurred between the two periods,with the Pliocene–Pleistocene denudation rate being five times higher than that during the Miocene.This abrupt change in denudation rate during Pliocene pervaded the Himalayan orogen,and was roughly synchronous with a marked change in global climate at 4–3 Ma,and intensification of the Asian monsoon.Importantly,the later period of rapid denudation in the study region closely coupled to the mean annual precipitation,while there is no clear evidence for large-scale faulting activity and a展开更多
6Lo WPAN(IPv6 over Low-Power Wireless Personal Area Networks)定义了IPv6报文如何在IEEE802.15.4网络上传输。其中难点主要在于适配层的报头压缩,这对于增大有效负载的空间非常重要,因为IEEE802.15.4留给上层协议的空间只有81字节...6Lo WPAN(IPv6 over Low-Power Wireless Personal Area Networks)定义了IPv6报文如何在IEEE802.15.4网络上传输。其中难点主要在于适配层的报头压缩,这对于增大有效负载的空间非常重要,因为IEEE802.15.4留给上层协议的空间只有81字节左右。简单介绍了了6Lo WPAN的几种现有的报头压缩算法,同时着重研究了一种通用的报头压缩算法6LOWPAN_GHC(以下简称GHC),并进行了实验验证。GHC可以看做是对通用报头及类报头有效载荷的一种补充算法,这样就不需要为新报头或者类包头有效载荷定义新的压缩规范了。展开更多
基金supported in part by Natural Science Foundation of Heilongjiang Province of China under Grant YQ2021F003in part by the National Natural Science Foundation of China under Grant 61901140+1 种基金in part by China Postdoctoral Science Foundation Funded Project under Grant 2019M650067in part by Science and Technology on Communication Networks Laboratory under Grant SCX21641X003。
文摘In this paper,the concept of computation diversity is proposed by employing generalized hybrid carrier(GHC)system.The signal is backed up by transform-domain computation to enhance the anti-fading capability.Theoretical analysis is presented to demonstrate the superiority of the proposed method.Numerical simulations in doubly-selective fading channels are provided to verify the results.The bit error rate(BER)performance is guaranteed with a small computational complexity increment.The proposed method not only extends the new diversity dimension,but also improves the diversity gain of the system without occupying additional wireless resources.Moreover,the proposed method shows good adaptability with single carrier modulation and improves diversity performance.As the simulation results shown,time-domain dual component computation diversity(TDC-CD)has 1d B BER gain and 0.1diversity gain at high signal-to-noise ratio,and single carrier system with TDC-CD achieves 2d B BER gain at 10~(-4).
基金supportedby the National Natural Science Foundation of China(41172176 and41121062)
文摘The Himalayan orogen characterized by very high variability in tectonic and climatic processes,and is thus regarded as a natural laboratory for investigating the coupling of tectonics and climate,as well as the influence of this coupling on geomorphological processes.This study uses apatite fission track(AFT)dating of samples from a45-km-long section crossing the Great Himalaya Crystalline Complex(GHC)in the Nyalam area,southern Tibet,to constrain the timing and rate of late Cenozoic denudation.The AFT ages can be divided into two groups:(1)15–6 Ma,to the north of Nyalam town,for which the bestfit line of elevation-age has a gentle slope of 0.05,and for which a denudation rate of 0.27 mm/a is calculated;and(2)3–1 Ma,south of Nyalam town,for which the best-fit line has a steep slope of 0.64,and for which a denudation rate of 1.32 mm/a is calculated.The whole AFT ages has a positive correlation with sample elevation(i.e.,older ages are found at higher elevations),and the geographical location of the point of inflexion of the two fitted lines corresponds closely to the junction of Poqu River near Nyalam town.By integrating the AFT data with thermotectonic modeling,it can be inferred that the GHC has experienced two different periods of denudation:(1)slow denudation during middle to late Miocene(15–6 Ma)is recorded in the northern part of the GHC;and(2)rapid denudation from the Pliocene to the Pleistocene(3–1 Ma)is recorded in the southern part of the GHC.An abrupt change in denudation rate occurred between the two periods,with the Pliocene–Pleistocene denudation rate being five times higher than that during the Miocene.This abrupt change in denudation rate during Pliocene pervaded the Himalayan orogen,and was roughly synchronous with a marked change in global climate at 4–3 Ma,and intensification of the Asian monsoon.Importantly,the later period of rapid denudation in the study region closely coupled to the mean annual precipitation,while there is no clear evidence for large-scale faulting activity and a
文摘6Lo WPAN(IPv6 over Low-Power Wireless Personal Area Networks)定义了IPv6报文如何在IEEE802.15.4网络上传输。其中难点主要在于适配层的报头压缩,这对于增大有效负载的空间非常重要,因为IEEE802.15.4留给上层协议的空间只有81字节左右。简单介绍了了6Lo WPAN的几种现有的报头压缩算法,同时着重研究了一种通用的报头压缩算法6LOWPAN_GHC(以下简称GHC),并进行了实验验证。GHC可以看做是对通用报头及类报头有效载荷的一种补充算法,这样就不需要为新报头或者类包头有效载荷定义新的压缩规范了。
