考虑红外焦平面器件非线性响应的一种非均匀性校正方法

针对红外焦平面阵列的非线性响应特性,提出了一种考虑非线性响应的“曲线—直线”校正方法,并给出了校正的计算公式.仿真实验结果说明此方法具有精度高,计算量小的优点,需要存储的参数少,易于硬件实现.     

透射式固态电光扫描器设计

针对红外成像系统常用光机扫描器的不足,提出了没有机械运动部件的全固态电光扫描器设计方法,给出了几种透射式固态电光扫描器结构,主要包括扫描列阵、耦合波导和控制电路三个部分.工作原理是：通过控制电路顺序控制各扫描单元光信号的传输,再通过耦合波导将光信号耦合到探测器上实现扫描成像.扫描列阵将完整图像分割成图像单元,耦合波导将空间位置不同的图像单元耦合到红外焦平面探测器上,控制电路用来控制扫描列阵各图像单元的工作状态.这种扫描器体积小、重量轻、结构紧凑,采用与红外焦平面探测器制作工艺相似的半导体制作工艺,具有与探测器集成的技术基础,控制起来更加方便.     

双曲柱面-平面透镜对半导体激光光束的准直性能

根据光线传播的基本原理,位于偏心率恰为相对折射率的双曲折射面外侧焦点上的点光源所发出的发散光,经折射后可成为较为理想的准直光束、因而可以制作用于半导体激光二极管条快轴方向准直的双曲柱面-平面透镜。本文通过计算和推导,用解析式表达并讨论了半导体激光器快轴方向发散光束通过双曲柱面-平面透镜后的半宽度、光强分布和光能转换效率,为正确认识和使用微双曲柱面-平面透镜改善半导体激光快轴方向光束的发散,提高光束质量提供了理论依据。     

A review of computational modeling and deep brain stimulation: applications to Parkinson's disease

Biophysical computational models are complementary to experiments and theories, providing powerful tools for the study of neurological diseases. The focus of this review is the dynamic modeling and control strategies of Parkinson's disease (PD). In previous studies, the development of parkinsonian network dynamics modeling has made great progress. Modeling mainly focuses on the cortex-thalamus-basal ganglia (CTBG) circuit and its sub-circuits, which helps to explore the dynamic behavior of the parkinsonian network, such as synchronization. Deep brain stimulation (DBS) is an effective strategy for the treatment of PD. At present, many studies are based on the side effects of the DBS. However, the translation from modeling results to clinical disease mitigation therapy still faces huge challenges. Here, we introduce the progress of DBS improvement. Its specific purpose is to develop novel DBS treatment methods, optimize the treatment effect of DBS for each patient, and focus on the study in closed-loop DBS. Our goal is to review the inspiration and insights gained by combining the system theory with these computational models to analyze neurodynamics and optimize DBS treatment.     

基于SWT方法的钢绞线索微动疲劳特性分析

为得到钢绞线索丝间接触区的应力场分布并预测微动疲劳裂纹萌生位置和微动疲劳寿命,本文利用参数化方法建立了精细化的钢绞线拉索有限元模型,包括整索模型和不同层丝间接触区域的局部精细化子模型．分析了钢绞线索在两种交变荷载工况下的应力场变化情况,并基于多轴疲劳SWT(Smith-Watson-Topper)临界平面法进行了疲劳特性分析和疲劳寿命预测．主要结论如下：钢绞线索内接触区边缘处的微动幅值较大,中心处几乎没有相对滑动,微动疲劳的初始裂纹萌生点位于接触区域边缘;经不同区域子模型分析比较,在轴向循环荷载作用下,外层钢丝的接触区域比内层钢丝更易发生微动疲劳损伤;在横向位移循环荷载作用下,同层钢丝因位置角度不同而产生了较大的疲劳特性差异,且相比轴向循环拉伸,该工况下最不利单丝的微动疲劳寿命更低;与非接触区域相比,接触区的疲劳寿命大幅降低,微动现象对钢绞线索的抗疲劳性能有明显降低作用．     

A hybrid numerical approach to predict the vibrational responses of panels excited by a turbulent boundary layer

In this work, a hybrid numerical approach to predict the vibrational responses of planar structures excited by a turbulent boundary layer is presented. The approach combines an uncorrelated wall plane wave technique with the finite element method. The wall pressure field induced by a turbulent boundary layer is obtained as a set of uncorrelated wall pressure plane waves. The amplitude of these plane waves are determined from the cross spectrum density function of the wall pressure field given either by empirical models from literature or from experimental data. The response of the planar structure subject to a turbulent boundary layer excitation is then obtained from an ensemble average of the different realizations. The numerical technique is computationally efficient as it rapidly converges using a small number of realizations. To demonstrate the method, the vibrational responses of two panels with simply supported or clamped boundary conditions and excited by a turbulent flow are considered. In the case study comprising a plate with simply supported boundary conditions, an analytical solution is employed for verification of the method. For both cases studies, numerical results from the hybrid approach are compared with experimental data measured in two different anechoic wind tunnels.     

GMPLS的一种镜像保护恢复机制

对通用多协标记交换(GMPLS)在控制平面的保护恢复技术作了系统的分析和研究;引进了一种对链路信息进行备份恢复的镜像恢复机制,并对此机制进行了分析,提出了改进方案,有效地解决了"多余备份"的现象.     

平面弹性力学问题的离散元法

根据离散元的基本原理,基于变形体的理论提出了适用于平面弹性力学问题的界面位移、应变和应力模式,建立了求解平面弹性力学问题的离散元方程和相应的迭代求解方法.通过界面位移可以简洁地将位移和力的边界条件引入离散系统的控制方程,也可以方便地求解节点位移.数值算例表明,与具有相同网格的有限元结果相比,离散元能同时给出精度相对较高的应力解和精度相当的位移解.     

The Saint-Venant problem of plane bar under an axial force

I.PrefaceAsweknow,theSaint-Venanttheoryisawell-knownanduniversallyacceptedtheory.Butasoneofthegeneraltheoriesofelasticmechanics,itisnotprovedperfectely,althoughitistestedbyexperiments.Infact,onlyforthesimplestproblemofelasticity,itisnoteasytofindanalytics…     

平面应力条件下闭合断续节理岩体力学特性试验研究

通过平面应力条件下闭合断续节理岩体的破坏试验,采用自行研制的高压柔性加载装置施加垂向和侧向荷载,用千分表和激光散斑照相技术量测试体位移场,用应变花量测试体平面应力场． 结果表明,激光散斑法用于测定闭合断续节理岩体的位移场效果良好,其测值比对应点千分表测值偏小１４％ 左右．据所测得的位移场和应力场,研究了裂纹尖端应力场的演变及裂纹扩展的路径,分析了试体的变形和破坏特征,测定了翼裂纹初裂角,探讨了试体的破坏机理．