摘要:
Bipolar host material and thermally activated delayed fluorescent (TADF) emitter were used in hybrid white organic light-emitting diodes (OLEDs) with the aim to achieve high performance. First of all, the single color OLEDs was optimized by changing the thickness of hole transporting layer, electron transporting layer and the doping concentration of emission material. Then, white organic light-emitting diodes (WOLEDs) were fabricated on the basis of the former single color OLEDs by modifying the doping concentration of TADF emitter. Finally, an optimized white device shows the best results of 43.67 cd/A, 45.73 lm/W and 18.52% for current efficiency, power efficiency and external quantum efficiency, respectively. This research may supply a theoretical basis for the development of WOLEDs.
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:
为了减少数字锁相放大器中的数字信号处理模块在硬件实现时所占用的逻辑资源,采用多抽样率数字信号处理理论来降低被测信号的采样频率,设计了高性能的数字窄带低通滤波器。利用Hogenaur"剪除"理论的级联积分梳状(Cascade Integrator Comb,CIC)滤波器,在FPGA实现时不仅能够节省大量的硬件逻辑资源,而且提高了CIC滤波器的最小响应时间;利用内插二阶多项式滤波器(Interpolated Second Order Pofynomials,ISOP)使CIC滤波器通带衰减降低到0.4 dB左右。MATLAB与Modelsim联合仿真测试验证了设计的正确性与可行性。
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.
摘要:
为了实现两幅图像的半透明叠加的 VGA显示, 根据图像叠加原理和 VGA显示原理, 使用A l t e r a公司的F P GA芯片C y c l o n eⅣE P 4 C E 1 5 F 1 7 C 8作为控制核心,采用V e r i l o g HD L语言实现图像叠加A l p h a算法, 采用移位操作解决F P GA处理浮点运算问题, 通过外部按钮来控制图像的透明度. 用 F P GA 控制实现图像叠加的VGA实时显示, 该设计方案具有体积小、 成本低、 速度快、 工作稳定等优点. Mo d e l s i m仿真结果和实际显示效果验证了设计的正确性与可行性.
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:
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.