Statics of nonlinear elastic cable-stayed systems with slipping flexible cables

A design model is proposed to describe spatial cable-stayed systems with slipping cables. The basic variables of the displacement method are selected. A system of nonlinear equilibrium equations is derived from the condition of minimum potential energy, taking into account the large displacements of joints and the large deformations of cables. A method and formulas needed to iteratively solve the system of nonlinear equations are presented. Individual consideration is given to a cable net with prescribed tension. The computed results make it possible to fabricate and mark out cable rods and to assemble cable nets based on their geometry alone, without the need for force measurement __________ Translated from Prikladnaya Mekhanika, Vol. 42, No. 5, pp. 79–87, May 2006.     

Global dynamics of the cable under combined parametrical and external excitations

The chaotic dynamics and global bifurcations of the suspended elastic cable under combined parametric and external excitations are investigated. The non-linear equations of motion of the elastic cable to small vibration of one support are derived. The averaged equations are obtained by using the method of multiple scales. Based on the averaged equations, the theory of normal form and Maple program are used to obtain the explicit expressions of normal form associated with a double zero and a pair of pure imaginary eigenvalues. On the basis of the normal form, global bifurcation analysis of the parametrically and externally excited suspended elastic cable is given by a global perturbation method developed by Kovacic and Wiggins. The chaotic motion of the elastic cable is also found by numerical simulation.     

基于欧拉描述的两节点索单元非线性有限元法

本文针对柔性悬索结构几何非线性分析的特点,提出了一种用欧拉描述来表示的两节点索单元非线性有限元模型,在索元变形后的位置上由虚功能建立了非线有限元基本方程及切线刚度矩阵。这样建立的非线性有限元分析方法可充分考虑拉索的几何非线性特性的影响并给悬索结构的初始平衡分析带来方便,算例结果表明,本文方法是精确有效的。     

深海走航抛弃式测量仪器时变信道对传输性能的影响

由于环境的要求,深海走航抛弃式测量仪器信号传输大多使用有线信道,然而,信道的电阻抗随放线长度不断变化,严重影响了深海走航抛弃式测量仪器信道传输的稳定性.本文以国家海洋技术中心自主研发的走航抛弃式温度、盐度、湿度(XCTD)剖面仪的传输信道为原型,提出了一种动态分析有线信道对传输信号幅值和相位影响的方法.首先推导出各电路参数随信道长度变化的规律,建立简化的传输电路模型和该模型的传输函数.通过定性分析得出传输频率、分布电容和缠绕电感对信号相位的影响.利用MATLAB软件分析XCTD在动态放线过程中信道对信号幅值和相位的影响.研究结果可进一步指导抛弃式走航测量系统的电路设计,提高测量数据的精度和信号传输的稳定性.     

Plasma density evolution in plasma opening switch obtained by a time-resolved sensitive He-Ne interferometer

To understand the formation process of vacuum gap in coaxial microsecond conduction time plasma opening switch (POS), we have made measurements of the line-integrated plasma density during switch operation using a time-resolved sensitive He-Ne interferometer. The conduction current and conduction time in experiments are about 120 kA and 1 μs, respectively. As a result, more than 85% of conduction current has been transferred to an inductive load with rise time of 130 ns. The radial dependence of the density is measured by changing the radial location of the line-of-sight for shots with the same nominal POS parameters. During the conduction phase, the line-integrated plasma density in POS increases at all radial locations over the gun-only case by further ionization of material injected from the guns. The current conduction is observed to cause a radial redistribution of the switch plasma. A vacuum gap forms rapidly in the plasma at 5.5 mm from the center conductor, which is consistent with the location where magnetic pressure is the largest, allowing current to be transferred from the POS to the load.     

Electrochemical study of butylate: application to the analysis of water

A biochemical gas-sensor (bio-sniffer) was constructed for convenient measurement of odourless hydrogen peroxide (H₂O₂) vapour, which is harmful to skin and mucous membranes. An enzyme-immobilized membrane was fabricated by spreading the mixture of catalase and photo-crosslinkable polymer on a dialysis membrane. An H₂O₂ biosensor was constructed by attaching this catalase-immobilized membrane to the sensitive top of a Clark-type oxygen electrode, and the oxygen generation from the decomposition of H₂O₂ catalysed by catalase was measured amperometrically. This biosensor was first applied to the measurement of H₂O₂ solution and was able to quantify the concentrations of H₂O₂ solution from 0.02 to 10.0?mmol?L^?1. Then, this biosensor was applied to gaseous phase as a bio-sniffer and was able to detect the odourless H₂O₂ vapour with the calibration range from 0.5 to 30?ppm, where the threshold limit value assigned by the American Conference of Governmental Industrial Hygienists (1?ppm) is covered.     

Investigation of protein FTT1103 electroactivity using carbon and mercury electrodes. Surface-inhibition approach for disulfide oxidoreductases using silver amalgam powder

Recently, it was shown that electrochemical methods can be used for analysis of poorly water-soluble proteins and for study of their structural changes and intermolecular (protein–ligand) interactions. In this study, we focused on complex electrochemical investigation of recombinant protein FTT1103, a disulfide oxidoreductase with structural similarity to well described DsbA proteins. This thioredoxin-like periplasmic lipoprotein plays an important role in virulence of bacteria Francisella tularensis. For electrochemical analyses, adsorptive transfer (ex situ) square-wave voltammetry with pyrolytic graphite electrode, and alternating-current voltammetry and constant-current chronopotentiometric stripping analysis with mercury electrodes, including silver solid amalgam electrode (AgSAE) were used. AgSAE was used in poorly water-soluble protein analysis for the first time. In addition to basic redox, electrocatalytic and adsorption/desorption characterization of FTT1103, electrochemical methods were also used for sensitive determination of the protein at nanomolar level and study of its interaction with surface of AgSA microparticles. Proposed electrochemical protocol and AgSA surface-inhibition approach presented here could be used in future for biochemical studies focused on proteins associated with membranes as well as on those with disulfide oxidoreductase activity.     

Design and experiments for the waveguide to coaxial cable adapter of a cavity beam position monitor

The waveguide to coaxial cable adapter is very important to the cavity beam position monitor (CBPM) because it determines how much of the energy in the cavity could be coupled outside. In this paper, the waveguide to coaxial cable adapter of a CBPM is designed and experiments are conducted. The curve shapes of experiments and simulations are very similar and the difference in reflection is less than 0.1. This progress provides a reliable method for designing the adapter.     

Poly(N‐isopropylacrylamide)‐Based Polymers as Additive for Rapid Generation of Spheroid via Hanging Drop Method

Multicellular tumor spheroid (MCTS) mimics microenvironment for tumor formation and provides predictive insight for in vivo tests. The hanging drop (HD) method of spheroid generation is cost effective, but it is limited by a long time duration for spheroid development and a low rate of formation of larger spheroids. Toward addressing those limitations, thermoresponsive copolymers with poly(N‐isopropylacrylamide) (p(NIPA)) backbone are developed, to be used as additives in the MCTS formation via HD method. Upon investigation it is found that in the presence of the polymer, robust and compact spheroids are formed in a short duration of 48 h. Larger spheroids (350–600 µm) can be formed by increasing the number of cells. Spheroids are characterized for their 3D shape and different cellular layers, and drug uptake study is done to prove the efficacy of the spheroids generated in drug screening.     

黄河小浪底水利枢纽工程地下厂房洞室群块体介质力学模型实验──预应力锚索支护效果

本文采用块体介质力学模型试验方法，研究了地下洞室群围岩的受力特点，破坏形态和破坏机理；洞室围岩超载能力和开挖步序对围岩稳定性的影响；砂浆锚杆和预应力锚索的不同加固效果；验证喷锚支护设计方案的合理性。