A general approach for the stability analysis of the time-domain finite-element method for electromagnetic simulations

This paper presents a general approach for the stability analysis of the time-domain finite-element method (TDFEM) for electromagnetic simulations. Derived from the discrete system analysis, the approach determines the stability by analyzing the root-locus map of a characteristic equation and evaluating the spectral radius of the finite element system matrix. The approach is applicable to the TDFEM simulation involving dispersive media and to various temporal discretization schemes such as the central difference, forward difference, backward difference, and Newmark methods. It is shown that the stability of the TDFEM is determined by the material property and by the temporal and spatial discretization schemes. The proposed approach is applied to a variety of TDFEM schemes, which include: (1) time-domain finite-element modeling of dispersive media; (2) time-domain finite element-boundary integral method; (3) higher order TDFEM; and (4) orthogonal TDFEM. Numerical results demonstrate the validity of the proposed approach for stability analysis.     

高温退火非掺杂磷化铟制备半绝缘材料

对液封直拉(LEC)非掺磷化铟(InP)进行930℃ 80h的退火可重复制备直径为50和75mm的半绝缘 (SI)衬底.退火是在密封的石英管内纯磷(PP)或磷化铁(IP)两种气氛下进行的.测试结果表明IP-SI InP衬底具有很好的电学性质和均匀性,而PP-SI的均匀性和电学参数都很差.在IP-SI样品的PL谱中出现与深缺陷有关的荧光峰.光激电流谱的测量结果表明:在IP气氛下退火获得的半绝缘磷化铟中的缺陷明显比PP-SI磷化铟的要少.并对退火后磷化铟中形成缺陷的机理进行了探讨.     

无人机发展应用及反无手段研究

近年来无人机及蜂群作战方式如火如荼,如何对抗无人机也成为近程防空重点.本文对无人机特点及分类,无人机作战方式及发展进行研究,深入分析了反无体系构成和手段,最后就反无系统中雷达的发展方向和任务提出建议.     

无人水下航行器发展与应用

无人水下航行器作为无人运载平台的一个重要分支,在民用领域和军用领域都发挥着极其重要的作用。首先介绍了几个发达国家UUV的发展现状及其未来发展计划,强调了UUV的应用领域,如海洋探测与开发、水雷对抗、潜艇对抗等等,在此基础上分析了UUV发展必须突破的几项关键技术,如能源问题、自主导航、协同使用等等。     

基于最小二乘法标定寻北仪基座倾角测量系统的测量当量

为得到准确的基座倾斜量,提出一种基于最小二乘法标定寻北仪基座倾角测量系统的测量当量方法。阐述基于电解质型倾角传感器的寻北仪基座倾角测量系统的工作原理,对基座倾斜的大小和方向进行准确测量,利用基座倾斜与寻北精度影响量之间的数学模型,进行误差补偿,根据最小二乘法建立数据模型,进行数据拟合,当标定的当量与理论设计值相差较大时,可调整电路放大倍数,进行重新标定;当测量当量调整到与设计值基本一致,将最后测量当量标定值记录下来,写入单片机相应flash单元即可。结果表明:该测量方法可以快速简洁地确定测量当量,保证寻北精度。     

300 mm直径硅外延片均匀性控制方法

随着摩尔定律的逐步实现,大直径硅片的应用规模逐渐扩大,然而,大直径硅外延片的片内均匀性成为了外延的主要问题之一.使用具有五路进气结构的单片外延炉生长300 mm直径硅外延片.相对于传统的三路进气结构,五路进气可以分别对硅片表面的5个区域的气流进行调节,实现单独分区调控,从而提升了外延层厚度均匀性的可调性.实验中,采用两步外延方法,进一步提升了片内电阻率均匀性.通过对工艺参数进行优化,300 mm硅外延片的外延层厚度不均匀性达到0.8％,电阻率不均匀性为1.62％(边缘排除5 mm),成功提升了300 mm直径硅外延片的外延层厚度和电阻率均匀性控制水平.     

Regulation and Reconstruction of Cell Phenotype Gradients Along the Tendon-Bone Interface

Tendon–bone interface is prevalent in the human body. It is divided into four zones: tendon (soft tissue), unmineralized fibrocartilage, mineralized fibrocartilage, and bone (hard tissue). Tendon–bone interface is characterized by a cell phenotype gradient that appears in the different zones. The cell phenotype gradients at the tendon–bone interface are orchestrated by specific intracellular molecular mechanisms, extracellular factors, immune signals, and neurovascular factors. These features have inspired scientists to design systems that mimic natural cell phenotype gradients. These biomimetic systems include the construction of cell sheets, regulation of cellular microenvironments, and the design of gradient functional scaffolds. Exploration of methods to mimic cell phenotype gradients is instructional for future clinical applications in reconstituting the tendon–bone interface. The present review elucidates the gradient composition of the tendon–bone interface. The associated regulatory mechanisms and applications are discussed, with the anticipation of creating a mise en scène for future research in interface tissue engineering.     

探索电工电子课程多元化的过程性考核方式

考试是高校实现人才培养目标的落脚点,探索基于实践项目制作、基于信息化手段、基于非标考题等多元化的过程性考核方式改革,加大过程性考核的分值比重,增加过程性考核方式的趣味性和创新性,优化电类课程考核模式,进而达到全面提升电工电子课程的高阶性、创新性和挑战度的终极目标。     

Collective Organization Behaviors of Multi-Cell Systems Induced by Engineered ECM-Cell Mechanical Coupling

Cells in vivo are surrounded by fibrous extracellular matrix (ECM), which can mediate the propagation of active cellular forces through stressed fiber bundles and regulate various biological processes. However, the mechanisms for multi-cellular organization and collective dynamics induced by cell-ECM mechanical couplings, which are crucial for the development of novel ECM-based biomaterial for cell manipulation and biomechanical applications, remain poorly understood. Herein, the authors design an in vitro quasi-3D experimental system and demonstrate a transition between spreading and aggregating in collective organizational behaviors of discrete multi-cellular systems, induced by engineered ECM-cell mechanical coupling, with the observed phenomena and underlying mechanisms differing fundamentally from those of cell monolayers. During the process of collective cell organization, the collagen substrate undergoes reconstruction into a dense fiber network structure, which is correlated with local cellular density and consistent with observed enhanced cells' motility; and the weakening of fiber bundle formation within the hydrogel reduces cells’ movement. Moreover, cells can respond to the curvature and shape of the original cell population and form different aggregation patterns. These results elucidate important physical factors involved in collective cell organization and provide important references for potential applications of biomaterials in new therapies and tissue engineering.