太阳射电频谱图的自动轮廓检测与信息提取

射电精细结构是太阳爆发动态频谱图中一个重要的观测现象。为了达到更好提取精细结构轮廓,解读物理信息的目的。基于国家天文台怀柔观测站的2．6～3．8GHz频谱仪于2002年4月21日观测到的爆发现象,采用Levelset方法并加以改进,对原始图像进行轮廓提取,克服了以往此方法中存在遗漏检测的问题。此外对图像进行循环检测,取得了良好地检测结果。此后又对图像进行二值化提取,得到了二值化精细结构图像。最终统计出精细结构漂移率这一重要物理信息,为更好的理解太阳爆发机制提供了依据。     

自由空间光-布拉格光纤耦合效率仿真分析

根据电磁场模场匹配理论,分析了自由空间光-布拉格光纤的耦合效率.通过对空间光-布拉格光纤耦合效率的计算可以知道,耦合效率与布拉格光纤纤芯半径、焦点光斑光腰半径和纤芯波矢有关.通过优化合理选择空间光聚焦后光腰半径与布拉格光纤纤芯半径以及纤芯波矢可以有效提高耦合效率.本文还对外界振动造成耦合透镜与布拉格光纤对接不正而对空间光-布拉格光纤耦合效率影响进行了分析.这对光纤激光雷达系统以及空间光通信系统的空间光-布拉格光纤耦合效率分析具有极其重要的参考价值.     

Secure data sharing scheme supporting efficient synchronous evolution for ciphertext and key

The static property of stored ciphertext in cloud increases the probability that an attacker can crack the ciphertext by obtaining a key,while ciphertext and key updates based on key distribution and re-encryption are excessively expensive.For this problem,a secure data sharing scheme supporting efficient synchronous evolution for ciphertext and key (CKSE-SDS) was proposed.By introducing cryptography accumulator in broadcast encryption,mimicry transformation factor could be constructed supporting time-hopping periodically and efficient synchronous evolution for ciphertext and key could be achieved based on dynamic segmentation and fusion of ciphertext and key,which reduced certainty in the process of encryption and key distribution and increased the difficulty for attackers exploiting security vulnerabilities to obtain key to crack ciphertext as well.Theoretical analysis and security proofs show that the proposed scheme can support secure and efficient data access as well as reduce the probability of a successful attack effectively for an attacker,which can also enhance the system’s active security defense capability.     

激光熔覆成形中熔池表面温度场的检测与研究

针对激光熔覆成形中熔池表面温度场难以测量的问题,搭建了彩色CCD同轴测温系统。通过优化实验参数,该测温平台可获得清晰、稳定的熔池表面图像,对所拍图像进行处理和计算,可以得到熔池表面的温度场。为了验证得到的温度场是否准确,搭建了红外测温系统,通过对熔池表面不同区域进行测温,得到了与CCD测量结果基本吻合的熔池表面温度分布。两种不同的测温方式得到一致的温度场,说明此测温平台是实用、可靠的,为通过实时检测熔池表面温度进而控制熔覆成形系统打下基础。     

Deep reinforcement learning based resource allocation algorithm in cellular networks

In order to solve multi-objective optimization problem,a resource allocation algorithm based on deep reinforcement learning in cellular networks was proposed.Firstly,deep neural network (DNN) was built to optimize the transmission rate of cellular system and to complete the forward transmission process of the algorithm.Then,the Q-learning mechanism was utilized to construct the error function,which used energy efficiency as the rewards.The gradient descent method was used to train the weights of DNN,and the reverse training process of the algorithm was completed.The simulation results show that the proposed algorithm can determine optimization extent of optimal resource allocation scheme with rapid convergence ability,it is obviously superior to the other algorithms in terms of transmission rate and system energy consumption optimization.     

LED静电损伤在老化过程中的变化趋势

针对发光二极管(LED)的可靠性问题,将抗静电测试与高温老化实验结合,将蓝绿色发光材料制成的二极管分组,测试其经过老化过程后的光色参数变化。实验数据表明,蓝绿色LED裸片与封装样品老化过程中的衰减趋势有一定差异,老化程度与封装材料和发光材料的搭配方式有关。对于未被静电损伤的芯片,经过老化过程后,并没有出现静电损伤被放大导致功能性失效的现象,静电对其参数衰减无明显影响,与单一的老化实验趋势相似。对于经过静电击打后出现异常,无法正常发光的芯片,高温老化实验产生了使其迅速损坏和复原的情况。     

基于SystemVerilog的I^2C总线模块验证

针对I2C总线模块,介绍了一种基于Systemverilog验证环境的验证IP设计。这种基于面向对象设计的验证架构可以很容易地被重用。文中分析了基于Systemverilog验证环境的结构,并在介绍I2C总线协议的基础上,重点论述了验证环境中事务产生器及驱动器的设计     

二维光子晶体对耦合波导激光器侧模的调制研究

利用光子晶体的自准直效应来调制耦合波导激光器的侧模,并用时域有限差分（FDTD）方法对五通道和九通道耦合波导激光器进行仿真,成功改变了模式的传播方向,使得相邻光场之间的相位差从兀变为零。在两种耦合波导结构中分别获得了远场发散角为12°和7°的单峰,既兼顾了激光器的稳定性,又得到了高质量的光束。     

基于DPCM算法的测井数据压缩

由于现实中测井数据数据量大,数据传输实时性强,这就要求传输效率要尽可能地高。但是目前大多数油田仍采用直接传输采样数据的方式。因此提出了一种基于DPCM算法的测井数据传输方式。针对编码方式的特点,设计了编码流程图。对测井数据进行了相关的预处理,再进行编码实现。经仿真实验后发现,差值编码能够有效地去除数据之间的冗余,在保证编码压缩后的测井数据与原始测井数据误差不超过5%的情况下,经压缩后的测井数据量为原始测井数据量的1/2,因此测井数据的传输效率提高到了2倍。