大型火箭起飞横向漂移测量系统研究

本文论及了大型火箭发射起飞段横向漂移量的近距离高速摄影测量系统和数据处理方法。     

直流电机的数字同步锁相

在某高速摄影机中,我们采用了同步数字锁相环路,本文叙述该机中直流电机的数字同步锁相原理及其所用数字相位误差积分器线路的构成。     

CO_2焊接短路过渡过程的动态分析─短路液桥的动态变化与力学测算

ＣＯ＿２气体保护焊接是一种高效、节能和低成本的焊接方法，在钢结构焊接生产中得到了广泛的应用。但也存在着诸如：金属飞溅、焊缝成形较差等问题，要解决这些问题，必须首先对ＣＯ＿２焊接过程的电弧形态以及熔滴变化情况从理论上深入分析研究。本文以高速摄影与光线示波器同步进行拍摄，记录了ＣＯ＿２悍接短路过渡中熔滴的长大、缩颈、脱落的全过程以及相对应的电流电压波形。利用影片数据分析处理系统对所得影片及记录波形进行了分析处理，得到了熔滴过渡形成金属液桥爆断瞬间的最大电流值及所受合力的大小。从理论上更进一步研究了短路过渡的机理，建立了短路过渡的模型，这对正确调节焊接工艺规范，保证焊接质量具有重大的指导意义，研究结果表明：在常规短路过渡ＣＯ＿２焊接中，抑制飞溅是提高ＣＯ＿２焊接质量的关键，利用焊接规范来调节短路频率和短路峰值电流是抑制飞溅的主要途径。     

高速超声加工工具的研究与应用

本文将提供一种设计高速超声加工工具的新方法，并给出了高速超声加工工具的试验结果。     

Research for Horizontal Parallax Only Kinoform in 3D Display

The most promising 3D display technology lies in holographic display system. Kinform, whose theoretical diffraction efficiency is 100%, is the promising type of hologram. It is found that one of the greatest obstacles to the practical application of kinoform is the computational speed. A new model to increase the computational speed is proposed to solve the problem. In the proposed model named horizontal parallax only (HPO) kinoform, the vertical parallax is omitted because the human visual system cannot perceive the vertical parallax. Therefore, the computational speed for HPO kinform is many times faster than that for full parallax kinform. In this paper, both the theoretical basis and the experimental results of HPO kinoform are discussed.     

E. 高速全息摄影和激光干涉测量的进展

本文对高速全息摄影和激光干涉测量术的最新发展作了详细评述。     

A note on an algorithm for generalized fractional programs

We present a modification of an algorithm recently suggested by the same authors in this journal (Ref. 1). The speed of convergence is improved for the same complexity of computation.The research of S. Schaible was supported by Grants A4534 and A5408 from NSERC.     

An experimental study of impact-induced failure events in homogeneous layered materials using dynamic photoelasticity and high-speed photography

The generation and the subsequent evolution of dynamic failure events in homogeneous layered materials that occur within microseconds after impact were investigated experimentally. Tested configurations include three-layer and two-layer, bonded Homalite specimens featuring different bonding strengths. High-speed photography and dynamic photoelasticity were utilized to study the nature, sequence and interaction of failure modes. A series of complex failure modes was observed. In most cases, and at the early stages of the impact event, intra-layer failure (or bulk matrix failure) appeared in the form of cracks radiating from the impact point. These cracks were opening-dominated and their speeds were less than the crack branching speed of the Homalite. Subsequent crack branching in several forms was also observed. Mixed-mode inter-layer cracking (or interfacial debonding) was initiated when the intra-layer cracks approached the interface with a large incident angle. The dynamic interaction between inter-layer crack formation and intra-layer crack growth (or the so-called “Cook–Gordon Mechanism”) was visualized for the first time. Interfacial bonding played a significant role in impact damage spreading. Cracks arrested at weak bonds and the stress wave intensity was reduced dramatically by the use of a thin but ductile adhesive layer.     

间歇式高速摄影机的分辨率

文中讨论了间歇式高速摄影机分辨率的计算方法.     

Experimental determination of counterflow ignition temperatures and laminar flame speeds of C2–C3 hydrocarbons at atmospheric and elevated pressures

Experimental data were acquired for: (1) the ignition temperatures of nitrogen–diluted ethylene and propylene by counterflowing heated air for various strain rates and system pressures up to 7 atm; (2) the laminar flame speeds of mixtures of air with acetylene, ethylene, ethane, propylene, and propane, deduced from an outwardly propagating spherical flame in a constant-pressure chamber, for extensive ranges of lean-to-rich equivalence ratio and system pressure up to 5 atm. These data, respectively, relevant for low- to intermediate-temperature ignition chemistry and high-temperature flame chemistry, were subsequently compared with calculated results using a literature C₁–C₃ mechanism and an ethylene mechanism. Noticeable differences were observed in the comparison for both mechanisms, and sensitivity analyses were conducted to identify the reactions of importance.