消光式核壳二聚体传感器的设计与光谱特性分析

根据ITO/Au纳米核壳二聚体粒子在生物医学领域的应用合理性,设计了一种实时检测生物液体的核壳二聚体探针消光式传感器;由偶极子理论推导出输出波长与外界环境折射率关系;利用MATLAB设计ITO/Au纳米核壳二聚体粒子结构;采用软件DDSCAT7.3结合离散偶极近似法,利用二聚体有效半径模拟计算了300~950nm可见光到红外光波段不同核壳比、二聚体间距、以及不同介质折射率的消光光谱;根据传感芯片折射率与偶极共振、耦合八级共振的响应关系得出ITO/Au二聚体的折射率灵敏特性。与传统Ag/Au核壳纳米粒子相比,ITO/Au纳米核壳二聚体结构引入了可作为传感芯片灵敏性自参考参数的耦合八级共振峰,同时ITO/Au二聚体结构的折射率灵敏度可达到419nm/RIU。这些工作及其结果对制作消光式传感器具有重要的意义。     

The Cauchy problem for a spin-liquid model in three space dimensions

In this paper, we study the Cauchy problem for magnetic fluid of spin-liquid type with Mermin-Ho relation in the three-dimensional space and prove global existence and uniqueness of solutions. The proof is based on the equivalence relation between smooth solutions of the spin-liquid model and the systems of Schrödinger equations with Abelian gauge field. The Sobolev spaces with fractional derivatives are also used in our estimates.     

考虑制动力影响的大型客车舒适性分析

利用有限元法和动力平衡原理,建立了具有层间接触的沥青路面和13个自由度的大型客车人体三维模型。以不平顺作为激励,随机模拟车流分布,在不同制动情况下,从时域和频域两方面分析人-车-路耦合振动下车辆和人体的动力响应。时域分析采用客观评价标准和主观烦恼率相结合的方法,频域分析考虑人体共振、人的心理和生理因素。结果表明:随着制动力增大,人体的竖向加速度幅值不变,俯仰、侧倾加速度幅值都增大,但是俯仰加速度增幅远大于侧倾加速度的情况,人的舒适性变差,烦恼率增高;在紧急制动时,主频段对人体共振、心理和生理产生的影响很小,但是次主频段与人体某些器官固有频段重合,对人体共振、心理和生理产生的影响是不容忽视的。     

Time-dependent Ginzburg–Landau equations for multi-gap superconductors

We numerically solve the time-dependent Ginzburg–Landau equations for two-gap superconductors using the finite-element technique. The real-time simulation shows that at low magnetic field, the vortices in small-size samples tend to form clusters or other disorder structures. When the sample size is large, stripes appear in the pattern. These results are in good agreement with the previous experimental observations of the intriguing anomalous vortex pattern, providing a reliable theoretical basis for the future applications of multi-gap superconductors.     

AlGaN/GaN高电子迁移率器件外部边缘电容的物理模型

AlGaN/GaN HEMT外部边缘电容Cofd是由栅极垂直侧壁与二维电子气水平壁之间的电场构成的等效电容.本文基于保角映射法对Cofd进行物理建模,考虑沟道长度调制效应,研究外部偏置、阈值电压漂移和温度变化对Cofd的影响:随着漏源偏压从零开始增加,Cofd先保持不变再开始衰减,其衰减速率随栅源偏压的增加而减缓;AlGaN势垒层中施主杂质浓度的减小和Al组分的减小都可引起阈值电压的正向漂移,正向阈值漂移会加强沟道长度调制效应对Cofd的影响,导致Cofd呈线性衰减.在大漏极偏压工作情况下,Cofd对器件工作温度的变化更加敏感.     

Tightly coupled aeroelastic model implementation dedicated to fast aeroelastic tailoring optimisation of high aspect ratio composite wing

This paper presents the development of a code, called GEBTAero, dedicated to very flexible aircraft (VFA) aeroelasticity and especially the evaluation of aeroelastic tailoring effect on critical speeds. GEBTAero is an open source code consisting in a tightly coupling between a geometrically exact beam theory -and a finite state induced flow unsteady aerodynamic model, including an homogenisation tool. This model has been implemented in Fortran using GEBT code and optimised open source libraries with particular focus on computation speed. Besides a non linear transient dynamic simulation capacity, a particular focus is put on the fast critical speed computation strategy using a non-iterative modal approach about the geometrically non linear deformed shape of the wing with the computation of only a few aeroelastic modes. Computation speed and accuracy of this implementation is assessed using widely used aeroelastic test cases and compared successfully to other aeroelastic codes. Configurations using aeroelastic tailoring, which are the core target of this solver, are then evaluated numerically on a representative high aspect ratio anisotropic composite wing and a simple 2-ply composite laminates with both variable ply orientations. It illustrates the strong correlation between the structural bending/twisting coupling of an unbalanced composite laminates and its critical aeroelastic speed. It also shows the high sensitivity of ply orientation on the aeroelastic behaviour.     

Fundamental solution of steady oscillations in thermoelastic medium with voids

ABSTRACT

The article deals with the study of plane wave propagation in the thermoelastic medium in the presence of voids. The problem is considered in the context of three-phase-lag model of generalized thermoelasticity. There exists three longitudinal waves, namely elastic (E-mode), thermal (T-mode) and volume fraction (V-mode) in addition to transverse waves which get decoupled from the rest of motion and not affected by thermal and volume fraction fields. The fundamental solution of the system of differential equations in case of steady oscillations in terms of the elementary functions has been constructed. The phase velocity and attenuation coefficient of these waves are computed numerically and presented graphically.     

运用三维离散元技术模拟落锤撞击下奥克托今颗粒的点火燃烧过程

炸药颗粒的点火燃烧过程一直是人们关注的热点问题。近年来，三维离散元技术在中尺度观测颗粒材料的动力学过程中拥有显著优势。炸药燃烧属于颗粒材料的反应动力学，运用三维离散元技术(DM3)可以有效地观测炸药燃烧传播的过程。以奥克托今(HMX)颗粒为例，本文成功模拟并观测到了HMX颗粒的燃烧反应程度，确定了颗粒开始燃烧反应的时间，以及燃烧反应传播的时间。同时，结合落锤冲击颗粒的三维图像以及其表观压强和放热功率，得到了HMX颗粒燃烧反应、燃烧传播的整个反应动力学过程，包括颗粒在冲击加载下碎化塑性变形的过程，颗粒燃烧反应放热的过程，落锤回弹颗粒喷射的过程等。同时，进一步说明了尖顶颗粒更利于颗粒点火，平顶颗粒有抑制颗粒点火的能力。     

超音速等离子体炬的磁流体动力学数值研究

针对设计的喉径2mm、工作电流为100A的拉瓦尔喷嘴,在二维轴对称模型的基础上,对超音速等离子体炬中的流动及其外部射流进行了数值模拟。通过在阳极喷嘴内部采用基于磁矢量势的磁流体动力学模型,避免了对磁感应强度的复杂积分计算,得到了喷嘴内部多场耦合的结果及外部射流的流动状态,分析了喷嘴内部电磁场对等离子体的加速作用及射流发展过程。结果显示,等离子体经历了亚音速→跨音速→超音速的发展过程,最终获得2.3 Ma的超音速射流。研究结果为超音速等离子体炬的工业应用提供了理论基础。