维数连续可变康托尔集分层介质中波的反射透射特性

本文研究了波通过一类可连续控制分维的广义Cantor集合介质层的反射透射频谱特性。利用自相似性,给出了任意分维情况的一般计算方法,从而使我们能研究反射透射频谱随分维的变化特点,并认识到,在一般分维下,谱具有广义自相似性和“混沌”周期性,这是一种新的物理现象,必定蕴藏着一定的实用价值。     

The conductivity transition of aggregated Bi films

By analyzing the recent experimental and theoretical results, we find that the abrupt conductivity transition of an ultrathin aggregated film of bismuth during its growth is not describable by the Anderson transition or quantum percolation, but instead can be well described by a two-dimensional continuum model of classical percolation.     

Interface between topological and superconducting qubits

We propose and analyze an interface between a topological qubit and a superconducting flux qubit. In our scheme, the interaction between Majorana fermions in a topological insulator is coherently controlled by a superconducting phase that depends on the quantum state of the flux qubit. A controlled-phase gate, achieved by pulsing this interaction on and off, can transfer quantum information between the topological qubit and the superconducting qubit.     

基于可见与近红外光谱联用的柑桔黄龙病快速无损检测研究

黄龙病是柑桔果树的毁灭性病害,对柑桔产业危害巨大。基于模型平均理论,探讨联用可见与近红外光谱技术,提高柑桔黄龙病快速无损检测精度的可行性。采集记录柑桔叶片的可见与近红外光谱,经实时荧光定量PCR鉴别黄龙病叶片为轻度、中度和重度三类,缺素和正常样品也经PCR鉴定,共五类叶片。基于光谱直接拼接、光谱归一化拼接和模型平均三种不同策略,结合偏最小二乘判别分析(PLS-DA)和多元线性回归(MLR)方法,分别建立了柑桔黄龙病可见与近红外光谱联用无损检测模型。经比较发现,光谱联用模型的检测精度均高于可见或近红外单一检测模型,且经导数处理后的光谱直接拼接PLS-DA模型检测精度最高,模型预测相关系数为0.97,预测均方根误差为0.67,模型总误判率为3%,其原因是导数消除了光谱的基线漂移。光谱归一化拼接的PLS-DA模型检测精度次之,模型总误判率为7%。可见与近红外模型平均的检测精度最低,模型总误判率为7.2%。实验结果表明,联用可见与近红外光谱,结合光谱拼接方法,提高了柑桔黄龙病无损检测模型的检测精度,研究可为其他领域的光谱联用提供参考依据。     

343 nm飞秒激光制备微孔阵列以增强聚氨酯合成革透湿性

为了提高聚氨酯(PU)合成革透湿性,分别使用343 nm飞秒激光和作为对比的1030 nm飞秒激光及1064 nm纳秒激光制备微孔阵列。采用扫描电镜(SEM)和3D激光扫描显微镜对比研究了微孔形貌。结果表明,343 nm飞秒激光可以制备出效果最佳的微孔。此外,分析了3种激光与PU涂层的作用机理,揭示了343 nm飞秒激光合成革微钻孔过程仅表现为光化学烧蚀,光化学和光热烧蚀同时发生于1030 nm飞秒激光钻孔过程,而1064 nm纳秒激光只显示了光热烧蚀。激光合成革表面钻孔后,测量其透湿性和抗张力。结果显示: 微孔密度越大,皮革透湿性(WVP)越大而抗张力越低,脉冲重叠的增加会导致WVP的增加和抗张力的下降;同时,随着脉冲重叠从91.7%降到50%,微孔直径从45 μm降低到30 μm,而微孔锥度从0.7°增加到12.1°;当脉冲重叠率为91.7%,微孔密度为2550/cm²时,最大的WVP增长率为306%。     

Surface-enhanced Raman scattering of 4-mercaptobenzoic acid and hemoglobin adsorbed on self-assembled Ag monolayer films with different shapes

Polyvinylpyrrolidone (PVP)-protected silver nanostructures of various shapes, including nanocubes, nanospheres, and hybrid shapes with nanospheres and nanorods, on the surface of glass or Si substrates (PVP-Ag films) are prepared by using electrostatic self-assembly. With 4-mercaptobenzoic acid (4-MBA) as a probe molecule, it is demonstrated that the PVP-protected silver nanocubes films (PVP-Ag NCs) have better surface-enhanced Raman scattering (SERS) activity with an order of magnitude larger enhancement factors (EF) than the PVP-protected silver nanospheres films and the PVP-protected silver hybrid shapes films, which is confirmed by our numerical simulations. The EF of 4-MBA on the PVP-Ag NCs film are up to ~5.38 × 10⁶, and the detection limit is at least down to ~10^?8 M. The uniformity and reproducibility of the SERS signals on PVP-Ag NCs film are tested by point-to-point and batch-to-batch measurements. Meanwhile, the PVP-Ag films are also shown to be an excellent SERS substrate with good biocompatibility for hemoglobin detection. It is shown that the PVP-Ag NCs films can be used as excellent SERS substrate with good activity, uniformity, reproducibility, and biocompatibility and are promising for a myriad of chemical and biochemical sensing applications.     

Multisymplectic implicit and explicit methods for Klein–Gordon–Schrödinger equations

We propose multisymplectic implicit and explicit Fourier pseudospectral methods for the Klein-Gordon-Schrödinger equations. We prove that the implicit method satisfies the charge conservation law exactly. Both methods provide accurate solutions in long-time computations and simulate the soliton collision well. Numerical results show the abilities of the two methods in preserving charge, energy, and momentum conservation laws.     

Direct generation of a 10 GHz 816 fs pulse train from an erbium-fiber soliton laser with asynchronous phase modulation

By employing the technique of asynchronous mode locking, we have successfully demonstrated direct generation of stable 10 GHz 816 fs pulse trains with a supermode-suppression ratio >70 dB from a hybrid mode-locked Er-fiber laser. When the modulation frequency deviates from the cavity harmonic frequency by 15-40 kHz, stable femtosecond soliton pulses are formed. Our results demonstrate that asynchronous mode locking can act as an effective mechanism for achieving a shorter pulse width and for stabilizing high-repetition-rate pulse trains in soliton fiber lasers.     

Electrochemical performance of a nonaqueous rechargeable lithium-air battery

Nonaqueous rechargeable lithium-air battery has so high specific capacity and specific energy that it is being widely researched by academia, corporation, and different research institutes. When used in dried air and absorbing oxygen form the air, this battery is called lithium-air battery, and its specific capacity based on cathode active material (oxygen) is infinite. However, its cycle performance is very limited as reported by the state-of-the-art researches. This cycle problem is mainly caused by instability of electrolyte. Based on electroanalysis of materials’ electrochemical property, a stable electrolyte solvent (sulfolane) and a lithium salt LiBF₄ are selected as electrolytes in this work. Coupled with other eligible battery materials and careful assembly, the lithium-air battery exhibits favorable cycle performance. Above all, this lithium-air system is evaluated objectively in this paper.     

谐振式集成光学陀螺解调特性分析

基于激光器频率谱检测技术,沿着光的传输方向分析了光波在谐振式集成光学陀螺系统中的传播,结合输入信号特征,建立频域内的数学模型,通过数值仿真和实验得到了调频检测系统下的解调曲线。按照光的传输方向：激光器、声光晶体移频器、光波导环形谐振器、探测器,利用贝塞尔函数展开和光场耦合模理论分析了谐振式集成光学陀螺解调特性,及其调频调制检测系统解调输出信号与谐振频率偏差之间的关系。通过数值计算,分析了解调曲线的变化规律,得到了施加在激光器压电陶瓷驱动器上调制波形的最佳调制系数。在实验上搭建了激光器频率调制解调技术系统,得到了解调曲线。数值仿真和实验结果表明,当调制系数M=2时,线性工作区间斜率最大,解调曲线最好。实测形状与理论分析结果相符,从解调信号得到±2×10³ rad/s的陀螺动态范围。