Secrecy performance analysis on cooperative CR-NOMA network

In order to improve the secrecy performance of communication system and make efficient use of limited spectrum,overlay cognitive radio (OCR) technology was combined with non-orthogonal multiple access (NOMA) technology and the communication model was proposed,in which secondary network realized dynamic switching between assisting primary network communication and secondary network communication by sensing whether the primary user occupied the spectrum or not.Artificial noise (AN) aided technology was used in primary and secondary networks respectively to further improve the secrecy performance of the system.The secrecy performance of the system was studied by deducing the expressions of the primary and secondary network secrecy outage probability and secrecy throughput respectively.The simulation results show that the proposed cognitive cooperative NOMA communication scheme is beneficial in reducing secrecy outage probability and increasing secrecy throughput.Furthermore,the influence of AN power allocation factor on system performance is given.     

纳米电子束曝光

JEOL JBX-5000LS是矢量扫描的电子束曝光机.系统采用LaB6灯丝,可以工作在25kV和50kV的加速电压下.对该系统的分辨率、稳定性、场拼接和套刻精度进行了系列研究,得到了分辨率为30nm的图形,图形的套刻精度也优于40nm.     

Topology-aware peer-to-peer overlay network for Ad-hoc

The mismatch between the structured peer-to-peer (P2P) overlay network, which is based on Hashing, and the actual physical network, leads to query repeatedly passing through some nodes in the actual route when it is applied in Ad-hoc networks. An approach of getting an appropriate node identifier (ID) bearing its local physical information is proposed, in which the traditional theory of getting node ID through Hashing the node's Internet protocol (IP) address is abandoned, and a topology-aware overlay network suiting Ad-hoc networks is constructed. The simulation results show that the overlay network constructed in the proposed method can avoid the route being iteratively accessed. Meanwhile, it can effectively minimize the latency and improve the load balance.     

Overlay mark optimization for thick-film resist overlay metrology

For thick resist implant layers, such as a high voltage P well and a deep N well, systematic and uncorrectable overlay residues brought about by the tapered resist profiles were found. It was found that the tapered profile is closely related to the pattern density. Potential solutions of the manufacturing problem include hardening the film solidness or balancing the exposure density. In this paper, instead of focusing on the process change methodology,we intend to solve the issue of the overlay metrology error from the perspective of the overlay mark design. Based on the comparison of the overlay performances between the proposed overlay mark and the original design, it is shown that the optimized overlay mark target achieves better performance in terms of profiles, dynamic precision,tool induced shift (TIS), and residues. Furthermore, five types of overlay marks with dummy bars are studied, and a recommendation for the overlay marks is given.     

OMAC: A new access control architecture for overlay multicast communications

Multicast communications concern the transfer of data among multiple users. Multicast communications can be provided at the network layer—an example is IP multicast—or at the application layer, also called overlay multicast. An important issue in multicast communications is to control how different users—senders, receivers, and delivery nodes—access the transmitted data as well as the network resources. Many researchers have proposed solutions addressing access control in IP multicast. However, little attention has been paid to overlay multicast. In this paper, we investigate the access control issues in overlay multicast and present OMAC: a new solution to address these issues. OMAC provides access control for senders, receivers, and delivery nodes in overlay multicast. The proposed architecture, which is based on symmetric key cryptosystem, centralizes the authentication process in one server whereas it distributes the authorization process among the delivery nodes. Moreover, delivery nodes are utilized as a buffer zone between end systems and the authentication server, making it less exposed to malicious end systems. To evaluate our work, we have used simulation to compare the performance of OMAC against previous solutions. Results of the simulation show that OMAC outperforms previous multicast access control schemes. Copyright © 2010 John Wiley & Sons, Ltd.     

基于侧边抛磨与覆盖材料的光纤光栅温度补偿新方法

提出并演示验证了将负热光系数的聚合物材料覆盖在侧边抛磨光纤光栅的抛磨区实现光纤光栅温度补偿的新方法。实验结果表明,这种新方法的温度补偿效果良好,封装后的光纤光栅处在63～79℃的环境温度时,可使其温度敏感度降低为未补偿时的1/16;当处在58～101℃的环境温度时,其温度敏感度降低为未补偿时的1/4。温度补偿封装后的光纤光栅器件直径只有2mm,长度为20mm。     

基于CLAHE和多尺度细节融合的静脉图像增强算法

利用静脉识别原理采集的静脉图像通常模糊不清、难以分辨。传统的CLAHE算法虽然能够提高静脉图像的对比度,但是会丢失图像的一些细节信息。文章提出了一种基于CLAHE和多尺度细节融合的静脉图像增强算法。首先对静脉图像进行ROI提取,采用CLAHE算法增强静脉与手背间的对比度;然后利用多尺度细节融合算法得到静脉图像的细节图,再通过均值滤波滤除细节层中的高频噪声;最后把上面两种方法得到的图像加权叠加得到细节增强后的静脉图像。实验结果表明,该方法在提高静脉图像对比度的同时保留了原图像的细节信息。     

基于覆盖网络的灾后通信网络恢复策略

为解决灾后通信网络损毁故障恢复问题,基于覆盖网络提出了通信网络恢复新策略,应用覆盖网络与源路由实现了通信网络路径的多样性,系统恢复中选取最佳landmark,为网络流量重新确定传输路径,保证节点传输中可有效绕过灾后故障区域.同时考虑到灾后区域通信故障中极容易出现的信息爆炸情况,加入了拥塞感知恢复系统,构建了一种灾后通信网络恢复急救系统(Post-disas-ter Communication Network Recovery Emergency System,PES).该系统可借助较少的网络探测开销及时绕过通信损毁故障区域与信息爆炸拥堵节点位置,提高网络流量的传输效率,在短时间内实现通信网络的恢复重连.     

Study on optimization strategy for hybrid underlay/overlay spectrum sharing based on queuing model

In order to improve the licensed spectrum utilization in cognitive radio networks,and provide higher experience quality to system users,the optimizing strategies of the hybrid underlay/overlay spectrum sharing mode was studied.For secondary users,a queuing model with service time following two phase order exponential distribution was constructed,and a method to obtain the steady state distribution was presented for the system model.Based on reward-cost structure,individual optimization strategy with observable case and the Nash equilibrium strategy with unobservable case were discussed.With purpose of optimal social benefit and maximal spectrum incomes,the pricing policies for secondary users to use licensed spectrum were formulated.Using the system experiment,the relations among the different optimal strategies were investigated,and the rationality of the price mechanism was verified.By contrasting the optimal social benefits gained by hybrid underlay/overlay spectrum sharing mode,overlay spectrum sharing mode and underlay spectrum sharing mode,it is further shown that the social optimization strategy of hybrid overlay/underlay sharing mode is more effective and stable to fully use the spectrum resource.     

A topology and application‐aware relay path allocation scheme in multipath transport system based on application‐level relay

The ever‐increasing transmission requirements of quality of service (QoS)‐sensitive applications, especially real‐time multimedia applications, can hardly be met by the single path routing protocols. Multipath transmission mechanism is a feasible approach to provide QoS for various applications. On the basis of the general framework of multipath transport system based on application‐level relay, we present a relay path allocation scheme, whose goal is to select suitable relay paths, while balancing the overlay traffic among the different domains and relayers. With the application‐layer traffic optimization service under the standardization within the Internet Engineering Task Force (IETF), the controller has the topology‐aware ability to allocate relay paths with excellent routing performance. To further develop the universality of our method, the controller perceives transmission performance of relay overlay network through relayers' performance detection processes and, thus, has the application‐aware ability to allocate relay paths with excellent transmission performance for different applications by consulting application‐specific transmission metrics. Simulation results demonstrate that the proposed relay path allocation algorithm performs well in allocating superior relay paths and can balance the distribution of overlay traffic across domains in different network situations.