A family of lower- and higher-order transversal linearization techniques in non-linear stochastic engineering dynamics

Sample pathwise numerical integration of noise-driven engineering dynamical systems cannot generally be performed beyond a limited level of accuracy, especially when the noise processes are modelled using (filtered) white noises. Recently, a locally transversal linearization (LTL) strategy has been proposed by the author (Proc Roy Soc London A 2001; 457 :539–566) for direct integration of deterministic and stochastic non-linear dynamical systems. The present effort is focussed on a host of extensions along with detailed theoretical error analyses of the linearization approach, especially as applied to problems in non-linear stochastic engineering dynamics. Thus, to begin with, estimates of local and global error orders in the basic LTL scheme are obtained separately for the displacement and velocity vectors when the system is driven either by a set of additive noises or by an arbitrary combination of (independently evolving) additive and multiplicative noises. Following this, a new family of higher-order LTL schemes is proposed in order to improve upon the basic LTL method and the associated error orders are established. A stepwise implementation of the lower- and higher-order versions of the LTL method, along with certain computational aspects, is also outlined. The proposed schemes are numerically illustrated, to a limited extent, for a single degree-of-freedom (SDOF) and a two degree-of-freedom (TDOF) non-linear engineering systems under additive and/or multiplicative white noise excitations. Copyright © 2004 John Wiley & Sons, Ltd.     

A Modified Variational-Gradient Method for Quasilinear Equations

A modified variational-gradient method is proposed and substantiated for quasilinear operator equations in a Hilbert space.     

薄板坯连铸生产SS400钢工艺技术研究

对唐钢薄板坯连铸机生产的SS400钢的生产工艺进行了分析,认为薄板坯连铸机生产的SS400钢,在采取了精炼站在线定氧,将钢水全氧控制在25×10~(-6)左右,同时连铸采取保护浇注和轻压下等技术后,能够确保薄板坯连铸SS400钢的顺利浇注,轧制的板带材表面质量良好,机械性能符合要求。     

试论双点后方交会简便公式

根据双点后方交会的图形特点和已知条件，列出了方程组，推导出了双点后方交会直接计算座标的简便公式，同时求出了精度计算公式，以供测量人员参考     

用作图法测定R50的理论分析

研究了步、机枪射击密集度试验中弹着点半经的顺序统计量，给出了作图法测定Ｒ_（５０）的理论分析，得到了作图法是测定Ｒ_（５０）的好方法的结论．     

新型超微晶软磁合金FePCCuMoSi微观结构缺陷的正电子湮没研究

用正电子湮没方法研究了新型超微晶软磁合金的微观结构缺陷，样品选用的是在不同温度下退火的Ｆｅ８１Ｐ１２Ｃ３Ｃｕ１Ｍｏ０．５Ｓｉ２．５合金，结果表明，合金的微观结构构陷大小，密度随退火温度有规律地变化，这种现象可能与非晶的晶化过程有关。     

PSD激光直线度测量仪

介绍了采用PSD传感器设计的激光直线度测量的工作原理，以及激光器、光靶和计算机系统的设计。     

一种新的含水率校正方法

从研究流体流动规律出发,结合模拟井实验结果,建立了多参数、非线性的半理论和半实验含水率校正模型,提出了反映两相滑脱效应的滑动比概念,其计算方法物理意义清晰并具有明确的收敛边界。与模拟井实验结果进行对比,使用平方法降低了含水率校正误差。     

Modelling aerodynamic sound in the airways of a human body: A possible diagnostic tool

The sound generated aerodynamically by a pillow-like body simulating an obstacle in the human airway is observed through a soft wall from outside the duct. It is intended to provide a physical basis for an attempted medical diagnostic technique for detecting an obstacle by observing the sound during breathing. So far at least two kinds of sound have been identified: One is sound of the half-jet flow formed downstream of the obstacle, and the other is sound due to unsteady motion of the separation point on the curved surface of the obstacle. For simulating the flow condition downstream of the vocal cords during inhalation, cases with an obstacle at various positions relative to a jet flow are also examined. In this case, the sound due to the downstream obstacle exhibits a complicated dependence on the geometry and flow parameters. Nevertheless, increase in the sound, or more correctly, deformation in the sound power spectrum, due to the presence of an obstacle is detectable from outside, opening up possibilities of its use as a diagnostic aid. Dedicated to the late Professor Itiro Tani on the occasion of 5ACFM, Taejon, Korea     

计算机存储系统的9位字节单向错误检测码

本文介绍了一种计算机存储系统中的单向错误检测码，系统构成采用９位字节，其中８位数据位，１位校验位，并使用一个单独的附加奇偶校验字节。单向错误检测码有两类，一类每个字包含固定的奇偶校验位；另一类每个字节包含的检验位的构成方式是任意的。