通讯机构：
[Wang, X.] S;School of Mechanical Engineering, University of South China, Hengyang, China
关键词：
激光熔覆;TC4钛合金;SiO2-HA涂层;耐腐蚀性能;生物活性
摘要：
为提高医用TC4钛合金表面熔覆羟基磷灰石(HA)涂层的植入稳定性和生物活性, 采用激光熔覆方法制备出不同含硅量的CaP生物陶瓷涂层。利用扫描电子显微镜(SEM)和X射线衍射仪(XRD)表征了熔覆层组织形貌和物相组成。结果表明: 添加SiO2(1wt.%、3wt.%)后形成Ca2SiO4相, 熔覆层中部组织细化。通过电化学腐蚀和体外SBF浸泡实验研究了SiO2含量对涂层耐腐蚀性和生物活性的影响。电化学腐蚀结果表明: 随着SiO2含量的增大, 涂层表面腐蚀电流密度逐渐减小; 体外SBF浸泡结果表明: 添加SiO2可以加快涂层表面类骨磷灰石的形成, 其中, 添加SiO2为1wt.%时涂层表面类骨磷灰石呈均匀分布。因此, 低含量SiO2可以提高生物陶瓷涂层的耐腐蚀性和生物活性。 To improve the implantation stability and biological activity of the hydroxyapatite(HA) coating on the surface of medical TC4 titanium alloy, CaP bioceramic coating with different silicon contents were prepared by laser cladding method. Scanning electron microscopy(SEM) and X-ray diffractometry(XRD) were used to characterize the morphology and phase composition of the cladding layer. The results showed that the Ca2SiO4 phase was formed and the microstructure of the middle zone of the cladding layer was refined after adding SiO2(1wt.%, 3wt.%). The effects of SiO2 content on the corrosion resistance and bioactivity of the coating were investigated by electrochemical corrosion and in vitro SBF immersion experiments. Electrochemical corrosion results showed that the corrosion current density of the coating surface decreased with the increase of SiO2 content; The results of SBF soaking in vitro showed that the addition of SiO2 could accelerate the formation of bone-like apatite on the surface of the coating. When the content SiO2 was 1 wt.%, the surface of the coating-like bone apatite was uniformly distributed. Therefore, low-content SiO2 can improve the corrosion resistance and bioactivity of bioceramic coatings.
作者机构：
[孙楚光; 刘均环; 朱红梅; 何彬; 王新林] School of Mechanical Engineering, University of South China, Hengyang;421001, China;[陈志勇; 朱卫华] School of Electrical Engineering, University of South China, Hengyang;[孙楚光; 刘均环; 陈志勇; 朱卫华; 朱红梅; 何彬; 王新林] 421001, China;[王新林] 421001, China<&wdkj&>School of Electrical Engineering, University of South China, Hengyang
通讯机构：
[Wang, X.] S;School of Mechanical Engineering, University of South China, Hengyang, China
摘要：
We show that the group-velocity-led optical event horizon (OEH) in optical fibers provides a convenient way to actively control the propagation property of higher-order solitons by a comparatively weak dispersive wave (DW) pulse. It has been found numerically that clean soliton breakup, a process by which a second-order soliton completely splits into a pair of constituent solitons with vastly different power proportions after interacting with the weak DW pulse, will occur while external DWs become polychromatic. The temporal separation between both constituent solitons can be controlled by adjusting the power of the external DW. The more energetic main soliton is advanced/trailed in time depending on the selected frequency of input DW pulse. We have developed an analytic formalism describing the external acting-force (AF) perturbation. These results provide a fundamental explanation and physical scaling of optical pulse evolution in optical fibers and can find applications in improved supercontinuum sources.
摘要：
采用结合双温模型的分子动力学的方法, 数值模拟了脉宽100 fs, 能量密度为40~200 mJ/cm2的飞秒激光与CuZr非晶合金的相互作用过程。低能量密度下, 靶材的烧蚀机制主要表现为机械破碎; 高能量密度下, 热机械蚀除和相爆炸共同存在于靶材的烧蚀过程, 随着能量密度的增加, 相爆炸成为主要蚀除机制。利用径向分布函数分析了CuZr非晶合金结构的无序性, 分析结果表明, 激光能量密度由80 mJ/cm2增加到120 mJ/cm2时, 飞秒激光与靶材相互作用过程中, 材料内部的原子保持着无序状态, 材料未发生明显晶化。 The femtosecond laser ablating CuZr amorphous alloy has been simulated using the molecular dynamics method combined with the two temperature model. The duration of laser is 100 fs and the fluence is selected from 40 mJ/cm2 to 200 mJ/cm2. At low laser fluence, the ablation mechanism of the target material is mechanical spallation. At high laser fluence, thermo-mechanical removal and phase explosion co-exist in the ablation process of the target material, and with the increase of the fluence, the phase explosion becomes the main removal mechanism. The disordering of CuZr amorphous alloy structure is analyzed by the radial distribution function. The results indicate that material atomics maintain a disordered state and no obvious crystallization is observed when the laser fluence increases from 80 mJ/cm2 to 120 mJ/cm2 during ablation process.
作者机构：
[陈明慧; 朱红梅; 王新林] School of Mechanical Engineering, University of South China, Hengyang;Hunan;421001, China;[陈明慧; 朱红梅; 王新林] Hunan;[陈明慧; 朱红梅; 王新林] 421001, China
通讯机构：
[Zhu, H.-M.] S;School of Mechanical Engineering, University of South China, Hengyang, Hunan, China
作者机构：
[Zhu, Weihua; He, Hongyu; Guo, Wei; Wang, Xinlin; Sheng, Jiabing; Chen, Zhiyong; Wang, XL; Yuan, Zhi] Univ South China, Sch Elect Engn, Hengyang 421001, Peoples R China.;[Wang, Xinlin] Univ South China, Sch Mech Engn, Hengyang 421001, Peoples R China.
通讯机构：
[Chen, ZY; Wang, XL; Wang, Xinlin] U;Univ South China, Sch Elect Engn, Hengyang 421001, Peoples R China.;Univ South China, Sch Mech Engn, Hengyang 421001, Peoples R China.
关键词：
Enhanced optical transmission;Finite-difference time-domain;Localized surface plasmon resonance;Subwavelength metallic film hole arrays;Unit structural features
摘要：
The relation between the enhanced optical transmission and the unit structural features is studied by changing the unit structural features. 3D finite-difference time-domain method is employed to study the enhanced optical transmission of periodic subwavelength circular-sharps shaped hole arrays in metallic films which are deposited on a quartz substrate. The influences of the unit structural features on the enhanced optical transmission are investigated. It is found that the enhanced optical transmission strongly depends on the unit structural edge sharp features: the sharp acuity, numbers, and distributions. The sharp acuity and numbers influence the enhanced optical transmission via localized surface plasmon resonance mode. The sharp distributions affect the enhanced optical transmission equaling to the effect of polarization properties. The results show that the surface plasmons strongly depend on unit structure edge sharp features. Changing the unit structural edge sharp features, the properties of the enhanced optical transmission can be tailored. This paper provides theoretical support for building the various functions of new plasmonic devices.
摘要：
The delay time dependence of photoelectron spectra and state populations of three-level ladder K2 molecule is investigated by pump-probe pulses via time-dependent wave packet approach. The periodical motion of the wave packet with oscillating period 500 fs results in the periodical variation of photoelectron spectra. The photoelectron spectra show Autler-Townes double splitting at zero delay time, and no splitting at positive delay time. The periodical change of state populations with delay time can be ascribed to the coupling effect between the two pulses. It is found that the selectivity of the state populations may be attained by regulating the delay time. The results can provide some important basis for realizing the optical control of molecules experimentally.
通讯机构：
[Pang, Lihui] U;Univ South China, Sch Elect Engn, Hengyang, Peoples R China.
会议名称：
13th IEEE International Conference on Signal Processing (ICSP)
会议时间：
NOV 06-10, 2016
会议地点：
Chengdu, PEOPLES R CHINA
会议主办单位：
[Deng, Xianrong] MStar Semicond Inc, Hardware Designing Dept, Shenzhen, Peoples R China.^[Pang, Lihui;Wang, Xinlin] Univ South China, Sch Elect Engn, Hengyang, Peoples R China.^[Jiang, Kaili] Univ Elect Sci & Technol China, Sch Elect Engineer, Chengdu, Sichuan, Peoples R China.
会议论文集名称：
International Conference on Signal Processing
关键词：
single-channel;blind signal separation;empirical mode decomposition;FastICA;intrinsic mode function
摘要：
This paper presents a new methodology for single-channel blind signal separation (SCBSS) of time-frequency overlapped signals in electromagnetic surveillance domain. This method combines the complete ensemble empirical mode decomposition (CEEMD) with fast independent component analysis (FastICA). Firstly, the single-channel recording is decomposed into a set of intrinsic mode function (IMF) components by the method CEEMD with adaptive noise, for the residue and the number of shifting iterations of CEEMD are smaller than that of other empirical mode decomposition approach. The IMF components become the basis representing the original data. After selecting the usefull IMF components according to their power spectrum, FastICA is used to separate the source of interest in the original signal. Simulation results obtained in evaluating the proposed methodology's performance confirmed the feasibility and effectiveness of this algorithm.
摘要：
采用结合双温模型的分子动力学方法, 研究了典型脉宽飞秒脉冲激光与镍钛二元形状记忆合金相互作用时能量密度对靶材烧蚀深度的影响。模拟了脉宽为100 fs, 能量密度为0~125 mJ/cm2的单脉冲激光辐照90 nm厚镍钛合金薄膜的过程。模拟结果表明, 飞秒单脉冲激光烧蚀镍钛二元形状记忆合金会产生两种不同的烧蚀相。能量密度较低时, 烧蚀结果呈现弱烧蚀相, 烧蚀深度较低, 并且与光学穿透深度相关; 能量密度较高时, 烧蚀结果呈现强烧蚀相, 烧蚀深度大幅度增大。采用“拼花法”对高斯飞秒脉冲激光辐照镍钛靶材的形貌进行预测, 发现使用能量密度为阈值附近的飞秒激光辐照靶材时, 能够获得底部较为平坦的烧蚀弹坑。 The interaction between femtosecond laser and NiTi binary shape memory alloy is simulated by molecular dynamics method combining with two-temperature model. The effects of femtosecond laser fluence on the ablation depth are investigated. In the simulation, the NiTi shape memory alloy film with the depth of 90 nm is irradiated by the single pulse with the duration of 100 fs and the fluences varying from 0 to 125 mJ/cm2. The simulation results show that two different ablation phases exist for single pulse ablating NiTi shape memory alloy. For lower fluence, the ablating result presents gentle ablation phase, the ablation depth is lower and related with the optical penetration depth. For higher fluence, the ablating result presents strong ablation phase and the ablation depth increases markedly. Predicting the morphology of NiTi target irradiated by the single pulse via mosaic approach shows that more flat ablation craters at the bottom can be obtained by using femtosecond laser fluence near the ablation threshold to irradiate the target.
