To enhance the bandwidth efficiency of the guard interval （GI） assisted wireless communication system, an attractive scheme is proposed, which combines the functions of pilots and the GI together, so that the pilot ...To enhance the bandwidth efficiency of the guard interval （GI） assisted wireless communication system, an attractive scheme is proposed, which combines the functions of pilots and the GI together, so that the pilot resource used for estimating channel state is saved. Based on the proposed different known guard intervals （DKGI）, the time-domain channel estimation can be simply applied on the receiver side. After channel estimation, the receiver can employ the cyclic convolution restoring （CCR） function to reconstruct the cyclical convolution relationship between the signal and the channel, by which the receiver can also achieve good performance through the conventional 1-tap frequency domain equalization （FDE）.展开更多
Up to now, how to construct an efficient secure group signature scheme, which needs not to reset the system when some group members' signing keys are exposed, is still a difficult problem. A construction concernin...Up to now, how to construct an efficient secure group signature scheme, which needs not to reset the system when some group members' signing keys are exposed, is still a difficult problem. A construction concerning revocation of group members is an ideal one if it satisfies forward security which makes it more attractive for not sacrificing the security of past signatures of deleted members. This paper analyses the problem and gives a construction in which the group manager can be un-trustworthy. The scheme is efficient even when the number of revoked members is large.展开更多
Although stone palettes from the Naqada culture are well known, research has been focused mostly on those palettes which are richly decorated. However, streaks and fragments of individual signs are also often found on...Although stone palettes from the Naqada culture are well known, research has been focused mostly on those palettes which are richly decorated. However, streaks and fragments of individual signs are also often found on simple palettes of various shapes. This study shows that the majority of these palettes have quite a number of marks and sign fragments that have been made by different techniques and over a long period of time. This particularly applies to rhomboidal palettes, for most of which there are no ground to infer that they have been used for ritual purposes or for mixing beauty care compositions. It is more likely that they denote an early form of the visual symbol in later periods represented by the head of Ptah＇s staff.展开更多
The methods combined by test, field monitoring and theoretical analysis were adopted to do the systemic research on the rock mass from micro-structure to macro-deformation, and rheological model of Jinchuan rock mass ...The methods combined by test, field monitoring and theoretical analysis were adopted to do the systemic research on the rock mass from micro-structure to macro-deformation, and rheological model of Jinchuan rock mass was established to discuss the reasonable supporting time. Resuhs show that supporting after suitable stress and displacement release can benefit for the long-term stability of surrounding rock.展开更多
基金The National High Technology Research and Deve-lopment Program of China (863Program)(No.2002AA123031).
文摘To enhance the bandwidth efficiency of the guard interval （GI） assisted wireless communication system, an attractive scheme is proposed, which combines the functions of pilots and the GI together, so that the pilot resource used for estimating channel state is saved. Based on the proposed different known guard intervals （DKGI）, the time-domain channel estimation can be simply applied on the receiver side. After channel estimation, the receiver can employ the cyclic convolution restoring （CCR） function to reconstruct the cyclical convolution relationship between the signal and the channel, by which the receiver can also achieve good performance through the conventional 1-tap frequency domain equalization （FDE）.
基金the National Natural Science Foundation of China (No.60673081)the National Grand Foundation Research 863 Program of China (No.2006 AA01Z417).
文摘Up to now, how to construct an efficient secure group signature scheme, which needs not to reset the system when some group members' signing keys are exposed, is still a difficult problem. A construction concerning revocation of group members is an ideal one if it satisfies forward security which makes it more attractive for not sacrificing the security of past signatures of deleted members. This paper analyses the problem and gives a construction in which the group manager can be un-trustworthy. The scheme is efficient even when the number of revoked members is large.
文摘Although stone palettes from the Naqada culture are well known, research has been focused mostly on those palettes which are richly decorated. However, streaks and fragments of individual signs are also often found on simple palettes of various shapes. This study shows that the majority of these palettes have quite a number of marks and sign fragments that have been made by different techniques and over a long period of time. This particularly applies to rhomboidal palettes, for most of which there are no ground to infer that they have been used for ritual purposes or for mixing beauty care compositions. It is more likely that they denote an early form of the visual symbol in later periods represented by the head of Ptah＇s staff.
文摘The methods combined by test, field monitoring and theoretical analysis were adopted to do the systemic research on the rock mass from micro-structure to macro-deformation, and rheological model of Jinchuan rock mass was established to discuss the reasonable supporting time. Resuhs show that supporting after suitable stress and displacement release can benefit for the long-term stability of surrounding rock.
