Special cases in a control problem

A number of control problems for mechanical systems with feedback are reduced to a matrix algebraic Riccati equation. The exact solutions of matrix algebraic Riccati equations with singularities are presented. These singularities do not permit the use of standard solution procedures. Asymptotic solutions of these equations are found in the neighborhood of the singular points. These results can be used as test examples in developing new solution algorithms for matrix algebraic Riccati equations __________ Translated from Prikladnaya Mekhanika, Vol. 42, No. 2, pp. 113–120, February 2006.     

Mathematical models and solution algorithms for computational design of RC piles under structural effects

The paper presents mathematical models and solution algorithms for RC pile design, through scanning soil stratums from top to downwards with an interactive scanner band. The equilibrium of transferred loads from the superstructure, friction forces and tip bearing forces are considered for the design, which leads to optimum pile length. The most important contribution of this research for designers is supplying an efficient tool to obtain optimum pile length and reinforced concrete design of pile foundation systems. A program package has been developed in MATLAB depending on the proposed algorithm. Soil behaviors depending on external effects, active and passive zone distributions are considered. All possible effects in all freedom degrees are taken into account in design process. Stress and strain distributions due to axial loads, bending moments, shear forces and torsional moments may be monitored. The optimum pile length, cross section dimension and reinforcement details may be found by using developed algorithm.     

汶川震区文家沟泥石流成灾机理与特征

文家沟位于绵竹市清平乡,属于 5 ·12 汶川Ms8.0级地震极重灾区。地震发生后的3个汛期内,文家沟曾先后发生5次典型泥石流灾害,其中以2010年8月13日泥石流灾害最为严重,规模与灾情巨大,社会影响深远。在对文家沟泥石流跟踪调查的基础上,探讨了泥石流的成灾机理和特征。研究表明:(1)文家沟泥石流是地震和强降雨共同作用的结果,其成因可归纳为震因与物源以及雨因与水源两个方面,在整个泥石流形成和发生的过程中,呈现出洪流-侵蚀下切-崩滑-席卷-进一步侵蚀下切-进一步崩滑-增大泥石流规模—……的"滚雪球式"循环过程; (2)泥石流发生所需的雨量、雨强条件和水动力条件都显著降低,泥石流规模和雨量之间呈现出明显幂函数关系; (3)发生过程呈现出持续时间长、运动距离远的特征; (4)成灾过程呈现出明显的链式效应,危害形式多样; (5)泥石流频率呈现出高发性,规模呈现出放大性。最后提出了文家沟泥石流研究与防治的建议。     

文家沟巨型岩质滑坡高速远程运移特征分析

文家沟滑坡是汶川地震诱发的巨型高速远程岩质滑坡,其运移特征尚不明确。在现场调查的基础上,结合遥感解译,进一步深入研究其运移特征。分析得出,滑体自滑源区差异性启动,途经斜坡区铲刮坡表岩土体,随后以滑行、飞行等方式进入沟谷区,沿沟铲刮两岸坡体继续下行,与岸坡发生了5次明显的冲撞,逐步解体碎屑化,于第3次冲撞后开始大规模减速堆积,最终于沟口区停积。结果表明,地形是滑体运移堆积的主控因素,滑体的解体碎屑化和冲撞山体时的爬高、抛摔、越顶现象以及冲击气浪的形成等是高速行程的具体表现,碰撞是导致全程解体碎屑化的主要途径。     

PSD用于稳像仪稳像精度测试方法探讨

介绍位置灵敏探测器用于测试稳仪稳像精度的方法，给出了测试系统的组成和工作原理。     

Stability of Tokamak Equilibrium with Internal Transport Barrier against High n MHD Ballooning Mode

Internal transport barriers （ITBs） are phenomena associated with improved confinement mode of tokamak plasmas. Within the region where the ITB locates, the plasma pressure has a large gradient while the magnetic shear s has a minimum so that within and near the ITB, the absolute value of the shear is very low. Physics involved is plentiful, from the macroscopic （ MHD ） stability, to the suppression of microscopic instabilities thought to be responsible for anomalous transport. The treatment of very low shear also poses some theoretical difficulties.     

Designer Self-Assembling Peptide Materials for Diverse Applications

Summary: Macromolecuar chemistry and polymer science have had an enormous impact in many areas of science, engineering, medicine and our daily life. It has not only changed our way of life forever, but also continuously to improve our living standard. Macromolecuar chemistry now also encompasses bioengineering, biomimetics, designer biological materials and nanobiotechnology. Here we summarize a few classes of short peptides that we discovered and invented with broad applications including 3D tissue cell culture, reparative and regenerative medicine, tissue engineering, slow drug release, stabilization of membrane proteins for develop nanobiotechnology and molecular devices. Molecular design using short peptides as new materials will play increasingly important role in biomedical research, nanobiotechnology, clinical science and medicine.     

On a new 3D model for incompressible euler and navier-stokes equations

In this paper, we investigate some new properties of the incompressible Euler and Navier-Stokes equations by studying a 3D model for axisymmetric 3D incompressible Euler and Navier-Stokes equations with swirl. The 3D model is derived by reformulating the axisymmetric 3D incompressible Euler and Navier-Stokes equations and then neglecting the convection term of the resulting equations. Some properties of this 3D model are reviewed. Finally, some potential features of the incompressible Euler and Navier-Stokes equations such as the stabilizing effect of the convection are presented.     

固体沿光轴方向的极缓慢速度和微小位移的激光多普勒测量

为了实现目标极缓慢速度和微小位移的实时、准确监测,消除各种干扰对微弱多普勒信号的影响,设计了一套激光多普勒测速(LDV)系统。该系统采用迈克尔逊干涉光路和调幅解调、相敏检测技术,具有较强的抗干扰能力。实验结果表明,该系统可实现固体目标沿光轴方向μm/s级速度和μm级位移的实时、准确测量。该系统光路结构简单,对目标的表面状况无特殊要求,可用于滑坡、地陷等地质灾害的监测,及桥梁、大坝等工程结构变形状况的检测,该方案对相关科学实验和工件精密测量也有重要意义。