高准确度温度变送器的研制

以铂电阻Pt100为例,设计了高准确度温度变送器。设计时,考虑了铂电阻的非线性问题,同时考虑了工业现场中参考电压波动、干扰等对温度测量的影响。定义了温敏系数概念,并以该系数作为设计的重要技术指标。实际应用表明,该变送器具有较高的测量准确度和较强的抗干扰能力。     

Modeling currency exchange rate time series

Previous studies have shown that a random walk model is an appropriate time series model for explaining exchange rate time series. This analysis is based on the assumption that the variance of an exchange rate time series is homogeneous with respect to time. This paper shows that this assumption may be violated for exchange rate time series. The monthly exchange rate of German Deutschemark per U.S. dollar is considered. The data ranges from March 1973 to December 1984. The starting point roughly coincides with the beginning of the floating rate regime. It is seen that a non-linear model would be more appropriate than a linear model for explaining this exchange rate time series.     

用C语言显示图形的基本方法

给出了用C语言初步图形程序设计的基本方法。主要以CGA(彩色图形适配器)为例,叙述了如何选择调色板,指定显示模式,显示缓冲器与位(bit)位置的相互关系,以及如何利用颜色来改变象素,画出相应曲线等关键问题。     

The non-linear behaviour of the NO-H2 reaction over Rh surfaces

In this paper we describe the non-linearity of the NO-H₂ reaction over Rh surfaces. Rate oscillations have been observed over a stepped (111) surface with (100) steps, (Rh(533) at low pressures (10^?4 Pa) below 500 K, while no oscillations could be observed under these conditions over a Rh(100) surface and a stepped (100) surface with (111) steps, Rh(711). The thermal stability of the N atoms formed during the reaction explains the observed structure sensitivity. Moreover, the results suggest that diffusion of N atoms is needed to synchronise the rate oscillations, a process that is absent on Rh(100) and Rh(711).     

A TEST FOR NON-LINEARITY OF PREDICTION IN TIME SERIES

Abstract. A test for non-linearity of prediction in time series is suggested; the test makes use of the partial correlation between a series and its square, eliminating linear terms. The distribution of partial correlation estimates is considered both theoretically and by simulation. Extensions of the test to include partial correlations with other nonlinear functions of the observed data are suggested. The nature of optimum predictors for some particular non-linear time series is described, and the performance of the test when used with simulated non-linear series is investigated.     

中厚板轧机垂直振动的非线性

根据4200轧机的实际参数,建立了轧机的两自由度非线性振动模型。采用Matlab软件编程求出了振动方程的数值解,并用分岔图和庞加莱映射的方法分析了振动系统随参激角频率变化的拟周期运动和混沌运动现象,以及轧件的刚度变化幅值对轧机振动状态的影响。结果表明,参激频率靠近固有频率附近,轧件的刚度较大时,轧机系统的非线性特征越显著,越容易失稳。     

轴对称有限元模型在轮胎设计中的应用

借助MARC有限元分析软件，考虑了轮胎的材料非线性、接触非线性以及大变形等复杂的力学特性，建立斜交轮胎的平面轴对称有限元分析模型，分析了该轮胎在离心载荷下的应力／应变场、接触及变形情况，以便进一步优化轮胎的结构，提高其性能。     

平面杆系几何非线性有限元程序中的几个问题

结合编程实践,从一个荷载步的非线性求解步骤、结点抗力的计算、结构内部铰结点的处理,等效结点荷载的处理、平衡迭代等方面总结了考虑几何非线性的平面杆系结构有限元程序编制过程中需要注意的几个问题,以供同行参考借鉴。     

钢管混凝土拱的材料非线性有限元分析

针对钢管混凝土拱桥计算的实体-梁单元法,详细地推导了该法的弹塑性切线刚度矩阵,在此基础上编写了钢管混凝土拱桥考虑材料非线性的极限承载力计算程序SYCFST,该程序得到了算例试验模型拱的验证。从而证明该程序的编写是正确的。