低码率活动图像编码

本文探讨了低码率活动图像编码的特点，对较新的图像编码标准Ｈ．２６３作了计算机模拟，和Ｈ２６１在相应的码率下作了比较，并对Ｈ．２６３的各选项的效果进行了讨论     

Analysis of M-ary FSK square law combiner under Nakagami fadingconditions

M-ary FSK transmission with square law combining over frequency non-selective m-distributed Nakagami fading with arbitrary m is studied. A closed form of the symbol error probability is derived and is verified by simulation to be accurate     

面向物联网隐私数据分析的分布式弹性网络回归学习算法

为了解决基于集中式算法的传统物联网数据分析处理方式易引发网络带宽压力过大、延迟过高以及数据隐私安全等问题,该文针对弹性网络回归这一典型的线性回归模型,提出一种面向物联网(IoT)的分布式学习算法。该算法基于交替方向乘子法(ADMM),将弹性网络回归目标优化问题分解为多个能够由物联网节点利用本地数据进行独立求解的子问题。不同于传统的集中式算法,该算法并不要求物联网节点将隐私数据上传至服务器进行训练,而仅仅传递本地训练的中间参数,再由服务器进行简单整合,以这样的协作方式经过多轮迭代获得最终结果。基于两个典型数据集的实验结果表明：该算法能够在几十轮迭代内快速收敛到最优解。相比于由单个节点独立训练模型的本地化算法,该算法提高了模型结果的有效性和准确性;相比于集中式算法,该算法在确保计算准确性和可扩展性的同时,可有效地保护个体隐私数据的安全性。     

Cluster-Based Saliency-Guided Content-Aware Image Retargeting

Straightforward image resizing operators without considering image contents (e.g., uniform scaling) cannot usually produce satisfactory results, while content-aware image retargeting aims to arbitrarily change image size while preserving visually prominent features. In this paper, a cluster-based saliency-guided seam carving algorithm for content-aware image retargeting is proposed. To cope with the main drawback of the original seam carving algorithm relying on only gradient-based image importance map, we integrate a gradient-based map and a cluster-based saliency map to generate a more reliable importance map, resulting in better single image retargeting results. Experimental results have demonstrated the efficacy of the proposed algorithm.     

一种稀疏分光配置约束下的WDM网络多播RWA算法

在波长路由WDM网络中,波长路由和波长分配是RWA算法提高光网络阻塞性能的两个重要阶段和关键技术。文章针对现有的稀疏分光配置约束下的光网络多播RWA算法复杂度高、代价高的问题,提出了一种新的稀疏分光器配置的RWA多播算法。该算法摒弃传统RWA算法在波长路由阶段就考虑稀疏分光约束能力的惯性思维,论文首次提出在波长分配阶段,才通过多播长转换器实现满足稀疏分光约束条件的分光能力传递。仿真结果表明,所提算法在平均代价和所需波长数目方面都获得了较优的性能。     

常用中波红外窗口材料高温透过与热辐射性能比较

在高超音速飞行下,飞行器的中波红外窗口面临着气动加热导致的高温透过率下降和高温辐射增强的挑战,在高马赫应用中,选择窗口材料时必须对材料的高温透过率与高温热辐射这两个性能进行考察.本文采用傅里叶红外光谱仪测试了蓝宝石单晶、钇铝石榴石单晶、镁铝尖晶石陶瓷、氟化镁陶瓷和氧化钇陶瓷5种常见中波红外窗口材料在50℃~400℃的高温透过性能和高温辐射性能.考察了这几种窗口材料的高温透过率下降趋势和高温辐射增强.结果表明,相对于其他3种材料,氟化镁和氧化钇材料在3~5μm应用波段的高温透过率下降很小,同样高温辐射也较小.此外,氧化钇表现出非常优异的超低红外辐射性能,是一种非常有应用前景的中波红外窗口材料.     

Modeling node mobility for reliable packet delivery in mobile ip networks

In this paper, we analyze node mobility for reliable packet delivery in mobile IP networks. In mobile IP, packets destined to roaming nodes are intercepted by their home agents and delivered via tunneling to their care of addresses (CoA). A mobile node may roam across multiple subnets. At each boundary crossing, a handoff is initiated such that the CoA is updated and a new tunnel is established. We consider both basic mobile IP handoff and smooth handoff. We find that reliable packet delivery in mobile IP networks can be modeled as a renewal process, because the retransmission over a new tunnel after each boundary crossing is independent of the previous history. We then derive the probability distribution of boundary crossings for each successful packet, based on which the packet reliable delivery time can be obtained. Our analytical model is derived based on a general distribution of residence time in a subnet and a general distribution of successful retransmission attempts in each subnet. The results can be readily applied to any distributions for both items. We also provide numerical examples to calculate the probability distribution of boundary crossings, and conduct simulations to validate our analytical results     

适用于轻载高效BUCK转换器的自举电路设计

提出了一种高压Buck转换器自举供电电路。该电路直接由芯片外部电源对自举电容充电,具有快速响应和大驱动电流等特点,满足大尺寸N型功率开关管的驱动要求。本设计适用于具有轻载高效模式的高压Buck转换器,在高端和低端开关管不工作时,能较好地对自举电容充电,解决了传统自举电路在低端管不工作时,无法稳定调节自举电压的问题。采用0.25 μm UMC工艺库仿真,结果显示,只需满足输入电压要求,即使低端开关管不工作,且负载具有较高电压时,该电路也能将自举电压维持在3.6 V以上,提高了转换器的可靠性。     

吸收栅对光折变晶体钛酸铋中两波混合能量转移的影响

基于钛酸铋晶体的吸收系数依赖于入射光强,考虑吸收栅对它的两波混合能量转移的影响,在某些近似条件下,推导出稳态两波耦合作用的表达式,与实验结果作了比较。测量了纯吸收栅的增益,给出结果。     

P-表示为经典位相的位相算符

以其P-表示为经典位相的要求我们定义了一种新的位相算符表达式,并指出它与Susski-nd-Glogower相算符的异同。