Nonlinear waves in a fluid-filled thin viscoelastic tube

In the present paper the propagation property of nonlinear waves in a thin viscoelastic tube filled with incom-pressible inviscid fluid is studied.The tube is considered to be made of an incompressible isotropic viscoelastic material described by Kelvin-Voigt model.Using the mass conservation and the momentum theorem of the fluid and radial dynamic equilibrium of an element of the tube wall,a set of nonlinear partial differential equations governing the prop-agation of nonlinear pressure wave in the solid-liquid coupled system is obtained.In the long-wave approximation the nonlinear far-field equations can be derived employing the reductive perturbation technique (RPT).Selecting the expo-nent α of the perturbation parameter in Gardner-Morikawa transformation according to the order of viscous coefficient η,three kinds of evolution equations with soliton solution,i.e.Korteweg-de Vries (KdV)-Burgers,KdV and Burgers equations are deduced.By means of the method of traveling-wave solution and numerical calculation,the propagation properties of solitary waves corresponding with these evolution equations are analysed in detail.Finally,as a example of practical application,the propagation of pressure pulses in large blood vessels is discussed.     

Hawking radiation of Kerr–Newman–de Sitter black hole

We extend the classical Damour–Ruffini method and discuss Hawking radiation in Kerr–Newman–de Sitter (KNdS) black hole. Under the condition that the total energy, angular momentum and charge of spacetime are conserved, taking the reaction of the radiation of the particle to the spacetime and the relation between the black hole event horizon and the cosmological horizon into consideration, we derive the black hole radiation spectrum. The radiation spectrum is no longer a pure thermal one. It is related to the change of the Bekenstein–Hawking entropy corresponding the black hole event horizon and the cosmological horizon. It is consistent with the underlying unitary theory.     

A phase field model for vesicle–substrate adhesion

In this paper, a phase field model is developed for vesicle adhesion involving complex substrate and vesicle geometries. The model takes into account an adhesion potential that depends on the distance of vesicle to the substrate. A variational problem is solved in a 3D computational domain by minimizing the contribution of bending elastic energy and the adhesion energy under the constraints of total surface area and volume, described via a phase function. An adaptive finite element method is used to efficiently compute the numerical solutions of the model. The computational results are validated through comparison of several axisymmetric shapes with the sharp-interface ODE solution. Moreover, we compute shapes for non-axisymmetric situations to support the observation that concave substrates favor adhesion.     

飞行器供配电系统地面通用测试接口设计

供配电地面测试负责为飞行器提供模拟供电、控制状态切换、采集并传输系统状态信息,配合完成全飞行器全周期的综合测试任务。本文首先简要介绍了供配电地面测试系统的基本功能和设备组成,然后对供电、控制、测量的接口设计进行分析,最后提出接口通用化设计方案。本文为电气系统地面通用化测试研究提供了有益尝试。     

基于二维直方图和模糊熵准则的阈值化方法

图像分割是图像分析、识别和理解的基础。图像分割主要是指将图像分成各具特性的区域并提取出感兴趣目标的技术,其研究多年来一直受到人们的高度重视;阈值化法是图像分割的一种重要方法,在图像处理与识别中广为应用;针对图像分割中细节往往被忽略导致后续处理困难的问题,基于模糊关系和最大模糊熵原理提出了一种阈值化方法,对二维直方图进行模糊分割;为了获得图像分割中的细节,提出的方法根据最大熵原则自动确定模糊区域和门限,进而获得二维模糊熵和遗传算法最优解,最后获得图像细节;通过对不同灰度水平和颜色类型图像进行实验比较,实验结果表明提出的方法优于二维非模糊方法和一维模糊熵分割法,得到该方法在图像分割中获得细节的结论。     

电动汽车充电站监控系统设计

针对电动汽车日渐普及这一情况,本论文设计了一套电动汽车充电站监控系统。首先,给出了监控系统总体结构;其次,选择了系统的通信方式,并给出详细的 CANET转换器配置和通讯编程实现;然后,基于Microsoft Visual Studio平台,利用C#开发了充电站上位机监控系统,该系统可实时监控充电桩及其配电系统的运行情况,保证了电动汽车充电站的安全运行。     

小型轻便式流速仪检定系统设计

为满足FP系列流速仪的计量检定需求,提出了一种小型便携式流速仪检定系统的设计方案。根据匀速运动时间等约束条件确定了环形水槽的几何参数。采用FPGA和上位机作为数据处理和控制核心,实现了对伺服电机转速的精确控制。设计了光电编码器和无线摄像机与上位机之间的通信方式,实现了检定装置标准流速值和被检仪器示值的数据读取。对测试数据的处理方法和测控软件的结构框架进行了分析。同时,对实验装置的测量误差进行了分析。结果表明,标准流速值的扩展不确定度为1.28×10-3m/s,检定装置符合量值传递要求,可作为FP系列流速仪计量检定的标准装置。     

An asymmetric imidazole derivative as potential fluorescent chemosensor for Fe in aqueous solution

A novel conjugated molecule, L, based on 2,4,5-triphenylimidazole and 6-phenyl-2,2′-bipyridine (HC^∧N^∧N) was synthesized in two steps. The molecule can recognize Fe³⁺ in aqueous solution (THF/H₂O, 1/1, v/v) by the appearance of new emission bands at 416 and 442 nm, which can be attributed to the emission of the newly formed L-Fe³⁺ complex. The binding constant of the complex was calculated to be (6.6±0.39)×10³ M⁻¹, and its formation was also confirmed by the appearance of isosbestic points at 312 and 381 nm in the UV-visible spectral titration experiment. While other transition and rare-earth metal ions, such as Mn²⁺, Fe²⁺, Co²⁺, Ni²⁺, Zn²⁺, Cd²⁺, Hg²⁺, Pb²⁺, Eu³⁺ and Nd³⁺, can only cause some decrease of L's fluorescence, alkali and alkaline earth metal ions, such as Li⁺, Na⁺, K⁺, Mg²⁺ and Ca²⁺, almost have no effect on L's fluorescence. The fluorescence of L can be recovered by the addition of EDTA to the L-Fe³⁺ system just due to EDTA's stronger chelating ability than that of L.     

Anisotropic partial differential equation noise-reduction algorithm based on fringe feature for ESPI

Noise reduction is one of the most exciting problems in electronic speckle pattern interferometry. We present a new anisotropic partial differential equation noise-reduction algorithm based on fringe orientation for interferometric fringe patterns. The proposed equation performs diffusion along the two directions of fringe gradient and isophote line, which are extracted accurately according to fringe feature. By restriction of diffusion in the gradient direction of fringe patterns, this method can provide optimal results in denoising but does not destroy fringe edges. The experimental results show that this technique is more capable of significantly improving the quality of the fringe patterns than the classical anisotropic diffusion equation proposed by Perona and Malik. Based on our filtered fringe patterns, the phase map obtained by phase-shifting technique can be extracted more accurately. It is an effective pre-processing method for electronic speckle pattern interferometry.     

Improved biological performance of low modulus Ti-24Nb-4Zr-7.9Sn implants due to surface modification by anodic oxidation

Dental implants are usually made from commercially pure titanium or titanium alloys. The purpose of this study was to evaluate the influence of surface treatment to low modulus Ti-24Nb-4Zr-7.9Sn (TNZS) on cell and bone responses. The TNZS alloy samples were modified using anodic oxidation (AD). Surface oxide properties were characterized by using various surface analytic techniques, involving scanning electron microscopy (SEM) equipped with energy dispersive spectrometer (EDS), X-ray diffractometry (XRD) and surface profilometer. During the AD treatment, porous titanium oxide layer was formed and Ca ions were incorporated into the oxide layer. The viability and morphology of osteoblasts on Ca-incorporated TNZS were studied. The bone responses of Ca-incorporated TNZS were evaluated by pull-out tests and morphological analysis after implantation in rabbit tibiae. The non-treated Ti and TNZS samples were used as the control. Significant increases in cell viability and pull-out forces (p < 0.05) were observed for Ca-incorporated TNZS implants compared with those for the control groups. Porous structures supplied positive guidance cues for osteoblasts to attach. The enhanced cell and bone responses to Ca-incorporated TNZS implants could be explained by the surface chemistry and microtopography.