Optimization of direct modulation rate for circular microlasers by adjusting mode Q factor

Semiconductor microcircular lasers have been investigated as potential light sources for photonic integrated circuits and optical interconnections for more than two decades. However, the direct modulation bandwidths of the circular microlasers remain a challenge, especially when being compared with other microlasers, such as photonic crystal lasers. In this paper, microcircular lasers connected to an output waveguide are investigated for high‐speed direct modulation with optimized mode Q factors. Small signal modulation with a resonance frequency of f_R = 12.5 GHz is realized for a AlGaInAs/InP circular microlaser with a radius of 10 µm at 290 K. Furthermore, clear eye diagrams are observed at 12.5 Gbit/s for a 15‐µm radius circular microlaser with f_R = 6.9 GHz.     

基于电光调制提高静态傅里叶干涉具光谱分辨率的研究

在静态干涉系统中,采用电光调制可变折射率晶体LiNbO₃做静态傅里叶干涉具的材料,两侧分别加载相位相反的调制信号,从而在不改变静态傅里叶干涉具尺寸的条件下提高光谱分辨率。通过推导光程差函数与折射率调制度的函数关系,计算得在折射率调制度为0.030的条件下,比同尺寸干涉具光谱分辨率提高了16.7倍,达到2.836 cm-1。仿真结果表明折射率调制度会因波长增大而减小,光程差函数会随干涉位置的增大而产生偏大的现象。实际探测过程中,由于光谱范围500～1 100 nm相对较窄,波长变化造成的光谱探测失真不大,可以通过标定补偿,所以应用该方法可以有效地提高静态干涉系统的光谱分辨率。     

茜素分光光度法测定磷霉素钠

在乙醇体系中,磷霉素钠与茜素发生反应,生成稳定的1∶1的络合物,溶液颜色发生明显改变,其最大吸收波长为545nm,磷霉素钠的浓度在1.4—60mg·L-1范围内遵守比耳定律,表观摩尔吸光系数ε=3.47×103L·mol-1.cm-1,基于以上反应,本方法测定药物制剂含量与文献方法一致,回收率在99.6%—100.5%之间,结果满意。     

一种新型无人机机载计算机同步策略研究

机载计算机是无人机的核心部件,其可靠性高低直接决定了系统的安全。余度技术作为机载计算机可靠性设计的一项重要手段,对提高系统的应变能力,实现故障隐蔽以消除故障,改善系统性能有十分重要的作用。但是在余度技术中不同通道之间会存在一定的时钟误差,如果不进行处理将会使其无法达到无缝切换,从而影响系统的安全。在对机载计算机内部通道间不同步的原因进行详细分析的基础上,提出了一种软、硬件相结合的同步算法,并以三余度机载计算机为例进行了实际测试。测试结果证明该策略实现简单、同步效果好,异步度完全满足系统要求且付出的软、硬件代价小,显著提高了全系统的可靠性及可维护性。     

Recommendation in evolving online networks

Recommender system is an effective tool to find the most relevant information for onlineusers. By analyzing the historical selection records of users, recommender system predictsthe most likely future links in the user-item network and accordingly constructs apersonalized recommendation list for each user. So far, the recommendation process ismostly investigated in static user-item networks. In this paper, we propose a model whichallows us to examine the performance of the state-of-the-art recommendation algorithms inevolving networks. We find that the recommendation accuracy in general decreases with timeif the evolution of the online network fully depends on the recommendation. Interestingly,some randomness in users’ choice can significantly improve the long-term accuracy of therecommendation algorithm. When a hybrid recommendation algorithm is applied, we find thatthe optimal parameter gradually shifts towards the diversity-favoring recommendationalgorithm, indicating that recommendation diversity is essential to keep a high long-termrecommendation accuracy. Finally, we confirm our conclusions by studying therecommendation on networks with the real evolution data.     

Weighted Composition Operators from the Bloch Spaces to Weighted Hardy Spaces on Bounded Symmetric Domains*

Let B_E be a bounded symmetric domain realized as the unit open ball of JB*-triples.The authors will characterize the bounded weighted composition operator from the Bloch space B(BE) to weighted Hardy space H_v^∞ in terms of Kobayashi distance.The authors also give a sufficient condition for the compactness,and also give the upper bound of its essential norm.As a corollary,they show that the boundedness and compactness are equivalent for composition operator fromB(B...     

带非线性源项的Riesz回火分数阶扩散方程的预估校正方法

本文针对带非线性源项的Riesz回火分数阶扩散方程,利用预估校正方法离散时间偏导数,并用修正的二阶Lubich回火差分算子逼近Riesz空间回火的分数阶偏导数,构造出一类新的数值格式.给出了数值格式在一定条件下的稳定性与收敛性分析,且该格式的时间与空间收敛阶均为二阶.数值试验表明数值方法是有效的.