Laser peening of aluminum alloy 7050 with fastener holes

The fatigue properties of laser peened aluminum alloy 7050 specimens with fastener holes were investigated. The surface profile and residual stress induced in the shock affected zone were characterized.Then,the fatigue specimens with notch were treated by laser peening(LP),and the fatigue lifes of LP-treated specimens were measured and compared with base materials without LP.The results indicated that LP improved the fatigue lifes of all tested specimens.The average fatigue lifes of specimens treated by LP before hole-drilling were 173% longer than those of untreated samples and had better effects than those specimens treated by LP after hole-drilling.     

药学专业药物化学实验教学现状与教学改革

从实验课与理论课相互关系、实验教学内容、与基础课的衔接、与相关课程的沟通和实验室管理等5个方面分析了药物化学实验教学中存在的问题,针对这些问题提出了改革措施,并对药学实验教学改革进行了展望。     

Computational design of proteins with novel structure and functions

Computational design of proteins is a relatively new field, where scientists search the enormous sequence space for sequences that can fold into desired structure and perform desired functions. With the computational approach, proteins can be designed, for example, as regulators of biological processes, novel enzymes, or as biotherapeutics. These approaches not only provide valuable information for understanding of sequence–structure–function relations in proteins, but also hold promise for applications to protein engineering and biomedical research. In this review, we briefly introduce the rationale for computational protein design, then summarize the recent progress in this field, including de novo protein design, enzyme design, and design of protein–protein interactions. Challenges and future prospects of this field are also discussed.     

电场调控Pt/Co∶ZnO/Nb∶SrTiO3异质结阻变与磁性研究

利用脉冲激光沉积法在0.7; Nb∶ SrTiO3衬底上制备了Co∶ ZnO薄膜,并构建了Pt/Co∶ ZnO/Nb∶ SrTiO3异质结器件.该器件表现出典型的双极性阻变效应,在正、负向电压作用下,器件电阻可以在低阻态和高阻态之间变换,电阻变换比值可达到104,阻态具有一定的保持性与耐久性,同时Co∶ ZnO薄膜的饱和磁化强度会产生与阻变相关联的可逆调控.结合ZnO薄膜阻变与磁性调控结果发现,氧空位在Co∶ ZnO/Nb∶ SrTiO3异质结的阻变及磁性调控中具有重要作用,并采用氧空位产生与湮灭结合载流子注入-束缚/解束缚模型解释阻变与磁性调控.     

CNN在煤矿突水水源LIF光谱图像识别的应用

煤矿突水类型的快速识别在矿井安全生产中意义重大,煤矿突水激光诱导荧光(LIF)光谱的识别方法,需要对光谱曲线进行预处理和特征提取,其过程较复杂,对此,提出了一种卷积神经网络(CNN)快速识别矿井突水类别的方法。根据煤矿矿井水层的分布特点和最常见煤矿突水类型,选取三种原始水样以及由原始水样混合的两种混合水为实验材料,利用LIF技术快速获取五种水样的200组荧光光谱曲线图,灰度化后输入CNN算法,其中150组光谱曲线图用于CNN的训练,剩余50组用于训练好的模型测试。模型测试中,CNN算法对实验水样光谱曲线图的识别率为100%,实验结果表明,CNN算法不仅能省去煤矿突水光谱图像识别中的数据处理和特征提取工作,而且还能快速有效的识别矿井突水类型。     

基于自相位锁定技术提升光电振荡器的稳定性

提出了一种基于自相位锁定技术提升光电振荡器稳定性的方法.通过监测光电振荡器环路中自身相位的变化来反馈控制光可调延迟线,提升光电振荡器输出频率稳定性.采用噪声模型进行了理论分析,并进行了实验验证.结果表明,带有反馈控制回路的自相位锁定光电振荡器在4 000s内的频率漂移量小于0.9ppm,其稳定性较自由运行的光电振荡器有了大幅度的提升.     

Dissipative Vortex Solitons in Defocusing Media with Spatially Inhomogeneous Nonlinear Absorption

In this paper, by solving a complex nonlinear Schr¨odinger equation, radially symmetric dissipative vortex solitons are obtained analytically and are tested numerically. We find that spatially inhomogeneous nonlinear absorption gives rise to the stability of dissipative vortex solitons in self-defocusing nonlinear medium in the presence of constant linear gain. Numerical simulation reveals the interaction effect among linear gain and nonlinear loss in the azimuthal modulation instabilities of these vortices suppression. Apart from the uniform linear gain indeed affects the stability of vortex in this media, another noticeable feature of current setup is that the steep spatial modulation of the nonlinear absorption can suppress sidelobes effectively and support stable vortex solitons in situations with uniform linear gain.Under appropriate conditions, the vortex solitons can propagate stably and feature no symmetry breaking, although the beams exhibit radical compression and amplification as they propagate.     

光源会聚角对生物组织光传输问题的影响

基于漫射理论, 建立了可处理任意空间光源照射下生物组织内光传输问题的计算模型, 并编制了相应的计算程序. 在此基础上, 通过大量的数值计算讨论了光源会聚角对组织内光场空间强度分布和组织漫反射场的影响. 结果表明：随着光源会聚角的增大, 组织内光场分布和组织漫反射的分布趋于集中, 当大于一特定角度之后, 光场强度的分布区域迅速扩大, 强度迅速下降, 同时强度出现极大值的位置开始偏离中心位置.     

水分胁迫对小麦光谱红边参数和产量变化的影响

在不同的水分胁迫梯度下,利用实验区小麦不同生长期光谱反射率观测数据,研究水分胁迫对小麦光谱反射率、红边参数及小麦产量的影响。首先分析水分胁迫对小麦光谱反射率的影响,然后利用小麦光谱反射率的一阶微分得到小麦光谱反射率的红边位置和红边幅度参数,分析了水分胁迫对小麦光谱红边参数的影响,最后利用水分胁迫下的红边幅度和小麦产量的关系,阐述了小麦水分胁迫下的光谱反射率特征与小麦产量的关系。研究结果表明,水分胁迫下小麦的红边位置在生长期前期出现红边位置红移现象,生长期后期出现红边位置蓝移现象。水分胁迫下的小麦的红边幅度在不同的生长期表现出不同的变化特征：生长期初期随着水分胁迫的增加而红边幅度增大,生长期后期随着水分胁迫的增加而红边幅度减小。小麦的红边幅度在拔节生长期前与小麦产量呈负相关而拔节生长期之后呈正相关,且不同生长期小麦的红边幅度与小麦的产量的相关系数不同。     

高温超导窄带低插损小型化双工器的仿真研究

采用IE3D软件,利用全波电磁仿真方法设计研究了高温超导窄带低插损小型化微波双工器,采用的材料是在厚度为0.5mm介电常数为23.5的LaALO3衬底上用磁控溅射法制备而成的双面氧化物高温超导薄膜Y B C O.利用在微波范围内,高温超导薄膜的Q值比常规导体高1～3个数量级的特点和其高介电常数的特点,实现了器件的低插损和小型化.