Substrate-induced anisotropy of c-axis textured NaxCoO2 thin films

Na_xCoO₂ [x = 0.51, 0.54, and 0.59] thin films have been grown on SrTiO₃ (100)-oriented single crystals with a 5° vicinal cut towards [010] by pulsed laser deposition. We analysed the films by X-ray diffractometry, atomic force microscopy (AFM), and dc-transport measurements. X-ray diffraction patterns of the films show single phase and c-axis textured growth with the film plane closely aligned to the [001]-direction of 5° miscut SrTiO₃ (001) substrates. In addition to the structural analysis of these films we performed transport measurements along and perpendicular to the substrate tilt direction and determined the resistivity anisotropy as a function of temperature. The results enable the development of a strategy for the fabrication of Na_xCoO₂ based thermoelectric thin film devices.     

An investigation of the surface-enhanced Raman scattering effect from new substrates of several kinds of nanowire arrays

Silver, titanium, nickel, and aluminum nanowire arrays with diameters from 90 to 110 nm were prepared on AAO templates by laser molecular beam epitaxy. On the several kinds of nanowire arrays, high-quality surface-enhanced Raman scattering (SERS) spectra of probe molecules of the red dye Sudan II (C(18)H(16)N(2)O) were obtained. In particular, the SERS spectrum of Sudan II on an aluminum nanowire array is reported for the first time.     

Effects of Time Delay on the Bistable System Subjected to Correlated Noises

The time-delayed bistable system subjected to the multiplicative and additive noises is investigated. In the condition of small delay time, the stationary probability distribution function （SPDF） is derived, and under the condition of large delay time, the SPDF is stochastically simulated. The analytical and simulative results indicate that： （i） For the case of λ = 0 （λ denotes the strength of correlations between the multiplicative and additive noises）, the time delay affects weakly the SPDF peak structure, and the symmetrical property of the SPDF two-peak structure does not change with the increasing delay time. （ii） For the case of λ≠0, the two-peak structure changes with the increasing delay time, i.e. one peak goes up and the other go down simultaneously as the delay time increases and along with further increase of the delay time, the lower peak disappears gradually while the higher one goes up, i.e. the structure of the SPDF changes from a bimodal to a unimodal and the system becomes monostable.     

基于虚拟时间反转镜的短基线定位研究

海洋的多途效应是影响水声定位信号检测性能的主要因素。为了满足信号检测中的某种"最佳"准则,克服海洋水声信道的多途效应,本文基于信道的匹配滤波器-时间反转镜技术,提出虚拟时间反转结合匹配滤波器构造信号处理接收机的方法。通过计算机仿真和实验数据处理表明,经过基于虚拟时间反转处理的匹配滤波(TR-MF)接收机性能优于传统的匹配滤波(MF)接收机,并且将该技术应用在短基线水声定位系统中,提高了时延估计分辨力,改善了定位精度。     

Wave propagation in fluid-filled single-walled carbon nanotube on analytically nonlocal Euler–Bernoulli beam model

An analytically nonlocal Euler–Bernoulli beam model for the wave propagation in fluid-filled single-walled carbon nanotube (SWCNT) is established. The governing equations with the nonlocal effects are derived on the variational principle, and used in the wave propagation analysis of the SWCNT beam. Compared with the partially nonlocal Euler–Bernoulli beam models used previously, the analytically nonlocal model presented in the present study predicts well the effects of the stiffness enhancement and the wave damping at the high wavenumber or the strong nonlocal effects area for the fluid-filled SWCNT beam. Though the analytical model is less sensitive than the partially nonlocal model when the moving velocity of the internal fluid is high enough, it simulates more of the high-order nonlocal effecting information than the partially nonlocal model does in many cases.     

Pb(Zr0.3Ti0.7)O3铁电薄膜激光感生电压效应

采用脉冲激光沉积(PLD)技术在LaSrAlTaO₃(LSATO),LaAlO₃(LAO)和SrTiO₃(STO)的单晶倾斜衬底上成功制备了Pb(Zr_0.3Ti_0.7)O₃(PZT)薄膜,在三种倾斜衬底上生长的PZT薄膜中都首次发现了LIV效应.对PZT/LSATO薄膜在a,c轴两种不同取向择优生长下的LIV效应做了研究,发现在薄膜c轴取向择优生长 关键词： 激光感生电压效应 铁电薄膜 薄膜生长取向 原子层热电堆     

蓝绿激光在鱼雷武器上的应用研究

目标识别功能是现代鱼雷武器应具有的基本功能。针对水下激光成像系统的特点,提出了将该系统应用于鱼雷自导／引信系统的设想并对其可行性进行了论证。蓝绿激光技术在鱼雷武器上的应用将有效增强鱼雷的目标识别能力和水下对抗能力,大大增强鱼雷武器的作战效能。     

The transverse laser induced thermoelectric voltages in step flow growth （1-x）Pb(Mg1/3Nb2/3)O3-xPbTiO3 thin films

This paper reports that the transverse laser induced thermoelectric voltages (LITV) are observed for the first time in the step flow growth (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-PT,x = 0.20, 0.33, 0.50) thin films deposited on vicinal-cut strontium titanate single crystal substrates. Because lead magnesium niobate-lead titanate is a solid solution of lead magnesium niobate (PMN) and lead titanate (PT), there are two types of signals. One is wide with a time response of a microsecond, and the other superimposed with the wide signal is narrow with a time response of a nanosecond. The transverse LITV signals depend on the ratio of PMN to PT drastically. Under the irradiation of 28-ns pulsed KrF excimer laser with the 248-nm wavelength,the largest induced voltage is observed in the 0.50Pb(Mg1/Nb2/3)O3-0.50PbTiO3 films. Moreover, the effects of film thickness, substrates, and tilt angles of substrates are also investigated.     

Mathematical modeling and bifurcation analysis of pro- and anti-tumor macrophages

More and more evidences show that macrophages can induce both pro-tumor and anti-tumor effects. The study on genetically engineered macrophages to kill tumor cells has become a new direction for anti-cancer therapy in recent years. In this paper, we propose a mathematical model of interactions between tumor cells, M1 and M2 macrophages, and study the stability and bifurcations around the interior equilibrium. It is shown that the model exhibits stable periodic oscillations bifurcating from Hopf bifurcation, which indicates the long-term coexistence of tumor cells, M1 and M2 macrophages as well as long-term tumor relapse. Furthermore, sensitivity analysis is performed to illustrate the effect of parameters on tumor size. Our results show that an increase in ξ (the ratio of activation rates by tumor cells of M2/M1 macrophages) leads to a decrease of tumor cells, which can be explained that ξ has significant effects on γ₁ (the transition rate from M1 to M2 macrophages) and γ₂ (the transition rate from M2 to M1 macrophages). Hence, the decay of tumor cells is not only the result of direct activation of M1 and M2 macrophages by tumor cells, but also the combined effect of the transition between M1 and M2 macrophages.     

基于GMRES算法的弹性结构强耦合小变形流激振动分析

使用混合广义变分原理,将基于Lagrange表述的小位移变形结构振动问题与基于Euler描述的不可压缩粘性流动问题,统一在功率平衡的框架下建立流固系统的耦合控制方程．用有限元格式做空间离散后,再用广义梯形法将有限元控制方程转化为增量型的线性方程组,该方程组的系数矩阵具有非对称性,其中元素含对流效应和时间因子．将GMRES算法与振动分析的Newmark法和流动分析的Hughes预测多修正法结合,发展成一种基于GMRES-Hughes-Newmark的稳定算法,用于计算具有复杂几何边界的强耦合流激振动问题．以混流式水轮机叶道为数值算例的计算表明,模拟结果与试验实测结果吻合较好．