海地瓜多糖脱色工艺研究

比较了活性炭、H2O2及大孔树脂对海地瓜多糖的脱色效果。从脱色率及多糖保留率两方面进行考察,树脂D392处理优于活性炭和H2O2,对其脱色工艺进行优化,通过响应面实验建立了数学模型,并确定树脂D392脱色的最优工艺为时间:5h,pH 10,温度:60℃,此时,脱色率达(84.2±0.6)%,多糖保留率为(82.9±1.1)%。研究工作有利于海参多糖品质的提高,为海参多糖后续研究及应用奠定了基础。     

红外双波段激光滤光膜的研制

为了满足红外军用仪器的特殊要求,根据薄膜理论进行了红外双波段滤光膜的膜系设计;采用电子束真空镀膜的方法,通过对工艺参数的调整,在多光谱ZnS基底上镀制了1 064nm高反、3～5μm高透的红外双波段滤光膜.利用低能离子轰击,使膜层与基底间的应力明显减小;使用BGS 6341薄膜应力测试仪,采用渐变梯度法,测得其压应力由...     

Bandwidth expansion and pulse shape optimized for 10 PW laser design via spectral shaping

We demonstrated a scheme of bandwidth expansion and pulse shape optimized to afford 10 PW laser design via spectral shaping, which uses the existing Nd:glass amplifier chain of the SG PW laser. Compared to the amplified pulse with a gain-narrowing effect, the required parameters of injected pulse energy, spectral bandwidth, and shape are analyzed, together with their influence on the system B-integral, energy output capability, and temporal intensity contrast. A bandwidth expansion to 7 nm by using LiNbO₃ birefringent spectral shaping resulted in an output energy of 2 kJ in a proof-of-principle experiment. The results are consistent with the theoretical prediction which suggests that the amplifier chain of SG PW laser is capable of achieving 6 kJ at the bandwidth of 7 nm and the B-integral < π . This will support a 10 PW laser with a compressed pulse energy of 4.8 kJ (efficiency=80%) at 480 fs.     

Finite-time complex projective synchronization of fractional-order complex-valued uncertain multi-link network and its image encryption application

Multi-link networks are universal in the real world such as relationship networks, transportation networks, and communication networks. It is significant to investigate the synchronization of the network with multi-link. In this paper, considering the complex network with uncertain parameters, new adaptive controller and update laws are proposed to ensure that complex-valued multilink network realizes finite-time complex projective synchronization (FTCPS). In addition, based on fractional-order Lyapunov functional method and finite-time stability theory, the criteria of FTCPS are derived and synchronization time is given which is associated with fractional order and control parameters. Meanwhile, numerical example is given to verify the validity of proposed finite-time complex projection strategy and analyze the relationship between synchronization time and fractional order and control parameters. Finally, the network is applied to image encryption, and the security analysis is carried out to verify the correctness of this method.     

超声波多次回波反射法测量两相流密度实验研究

本文利用超声波在一侧壁面内的多次反射确定两相流的声阻抗值,从一侧壁面通过两相流到另一侧壁面再反射回来的二次回波时差确定两相流中声速,对这两个数据采用超声多次回波测量理论进行处理,可以得到两相流密度和浓度.不同浓度下的水煤浆实验结果表明,该方法测量得到的结果与珲论值较为吻合.并且超声波多次回波反射法的测量装置具有结构简单,非侵入式测量,实时处理数据以及不受超声发射功率影响等优势,适合高浓度两相流密度和浓度的在线测量.     

Fabrication of Mn-Doped GaN Nanobars

We report a new method for large-scale production of GaMnN nanobars, by ammoniating Ga2O3 films doped with Mn under flowing ammonia atmosphere at 1000oC. The Mn-doped GaN sword-like nanobars are a single-crystal hexagonal structure, containing Mn up to 5.43 atom%. Thickness is about 100 nm and with a width of 200-400 nm. The nanobars are characterized by x-ray diffraction, scanning electron microscopy, x-ray photoelectron spectroscopy, high-resolution transmission electron microscopy and photoluminescence. The GaN nanobars show two emission bands with a well-defined PL peak at 388 nm and 409 nm respectively. The large distinct redshift （409 nm） are comparable to pure GaN（370 nm） at room temperature. The red-shift photoluminescence is due to Mn doping. The growth mechanism of crystalline GaN nanobars is discussed briefly.     

浅议"物理文化"的定义及传输问题

分析了国内相关学术著作中对“物理文化”所作的不同界定,讨论了物理文化的传输问题．     

热扩散不稳定和流体动力学不稳定对氢气/空气爆炸胞状火焰的影响

为揭示氢气/空气爆炸球形胞状火焰的传播特性,运用高速摄影技术实验研究了热扩散不稳定和流体动力学不稳定对胞状火焰结构、临界火焰半径、临界Peclet数和火焰燃烧速度的影响。结果表明:随着流体动力学不稳定的凸显,Lewis数大于1的火焰胞格尺度远大于Lewis数小于1的胞格尺度;同一初始压力下,火焰厚度随着当量比的增大呈先减小、后增大的趋势,临界火焰半径会随着当量比的增大而增大;同一当量比下,火焰厚度和临界火焰半径都会随着初始压力的升高而减小;当量比低于2.0时,不同初始压力下的临界Peclet数会随当量比的增大而线性增大;当量比为0.6,初始压力为0.05 MPa时的火焰燃烧速度最大。     

基于监督字典学习的核稀疏表示的目标识别算法（英文）

针对图像数据高度非线性可分情况下的目标分类问题,在稀疏表示分类框架的基础上,提出了一种基于监督字典学习的核稀疏表示的目标识别算法。采用融合了多特征信息的协方差描述子作为图像的描述符;通过引入核技巧,使非线性的图像数据在高维空间变得线性可分;并把分类误差与重构误差同时引入目标函数,在监督字典学习框架下,使学习得到的字典判别性更强。利用加州大学默塞德分校提供的UCMerced遥感数据集以及自测的红外车辆数据集做了实验验证,在这两个数据集上算法的平均识别率分别达到了89.46%和93.98%,实现了对非线性可分目标的高精度分类。     

Ni/Au/n-GaN肖特基二极管可导位错的电学模型

可导线性位错被普遍认为是GaN基器件泄漏电流的主要输运通道,但其精细的电学模型目前仍不清楚.鉴于此,本文基于对GaN肖特基二极管的电流输运机制分析提出可导位错的物理模型,重点强调:1)位于位错中心的深能级受主态(主要Ga空位)电离后库仑势较高,理论上对泄漏电流没有贡献; 2)位错周围的高浓度浅能级施主态电离后能形成势垒高度较低的薄表面耗尽层,可引发显著隧穿电流,成为主要漏电通道;3)并非传统N空位,认为O替代N所形成的浅能级施主缺陷应是引发漏电的主要电学态,其热激活能约为47.5 meV.本工作亦有助于理解其他GaN器件的电流输运和电学退化行为.