变差函数在地下水位估值中的应用研究

用数值方法进行地下水水资源评价时 ,需要给出每个节点上的初始地下水位值。本文着重阐述了区域化变量和变差函数及其计算步骤 ,指出变差函数在分析地下水位的空间变异的重要性     

固井声幅-变密度测井的影响因素分析

利用声幅－变密度测井进行固井质量的评价受到诸多因素的影响，各种影响因素对声幅－变密度测井资料的影响作用有较大的差异，根据大量测井资料分析和实验研究，对仪器偏心、测井时间，套管尺寸与重量，地层岩性，气侵、水泥环微间隔等因素的影响作用进行了较为深入的分析，为各种影响因素的识别与校正提出了相应的方法和依据。     

建筑墙体表面传热系数辨识研究

对实验房间南向墙体内表面中心区域的换热过程进行实验，发现当风速在0－5．5m/s之间时，表面传热系数在8－18W（m^2.K）之间波动，而风向对墙体表面传热系数影响不大；用辅助变量法分析墙体表面传热过程，并结合实验推导出墙体表面传热系数。模型的预测结果与实测结果吻合良好。     

大坝监测资料分析中环境量对效应量影响综合评价的加权面积法

用距离的概念来描述大坝监测资料分析中环境量对效应量的整体影响效应. 首先讨论了多种距离定量化准则, 其中加权面积距离是以分量过程线围成的面积对其基准值的矩经量纲归一处理后得到的值; 然后论证了使用加权面积定义距离的合理性并给出了确定距离基准值的方法, 为确定各个分量占效应量的比例提供了定量的依据. 最后给出了应用实例, 证明了该法的有效性.     

钻探用变量泥浆泵曲轴强度的计算

随着钻探业的不断发展 ,日趋需要大功率的泥浆泵 ,文章介绍了大变量泥浆泵机组中曲轴的设计。     

Random errors caused by temperature in magnitude of principal strains evaluated ith 3-element strain gauge rosettes

The effects of the uncertainties associated ith the apparent strain and gauge factor data, given by the manufacturer, in the evaluation of principal strains are examined. Principal strains are obtained by a reduction of the strains measured ith electrical resistance strain gauge rectangular or delta rosettes. The theoretical analysis points out the relevance of the effects caused.     

Optimization by random search with jumps

We give a random optimization (RO) algorithm to optimize a real‐valued function of n real variables. During the optimization process, interpolation points are examined to follow valleys, and jumps to new starting points are executed to avoid numerous iterations in local minima. Convergence with probability one to the global minimum of a function is proved. The proposed RO method is a simple, derivative‐free and computationally moderate algorithm, with excellent performance compared to other RO methods. Seven functions, which are commonly used to test the performance of optimization methods, are used to evaluate the performance of the RO algorithm given here. Copyright © 2004 John Wiley & Sons, Ltd.     

Control of discrete time nonlinear systems with a time-varying structure

In this paper, we present a control methodology for a class of discrete time nonlinear systems that depend on a possibly exogenous scheduling variable. This class of systems consists of an interpolation of nonlinear dynamic equations in strict feedback form, and it may represent systems with a time-varying nonlinear structure. Moreover, this class of systems is able to represent some cases of gain scheduling control, Takagi-Sugeno fuzzy systems, as well as input-output realizations of nonlinear systems which are approximated via localized linearizations. We present two control theorems, one using what we call a “global” approach (akin to traditional backstepping), and a “local” approach, our main result, where backstepping is again used but the control law is an interpolation of local control terms. An aircraft wing rock regulation problem with varying angle of attack is used to illustrate and compare the two approaches.     

The effect of ambient temperature on the sensitivity of hot-cathode ionization gauges

We measured the sensitivities of five hot-cathode ionization gauges for ambient laboratory temperatures between 23 and 31 °C. All of the ionization gauges exhibited very similar behavior, and the sensitivity could be adequately modeled with a linear function of temperature. The slopes of the fits were smaller than one would expect due to changes in the calibration chamber number density. The thermal transpiration effect, due to local heating of the gauge structures, can account for this, and a characteristic gauge tube temperature can be inferred from the temperature dependence of the sensitivity. A recent comparison of the high vacuum standards of several National Metrology Institutes (NMIs) was performed over the range of 10⁻⁶-10⁻³ Pa using hot-cathode and spinning rotor gauges as transfer standards. Among the participants, laboratory temperatures varied by as much as 5 °C. It is necessary to know how laboratory temperature affects the sensitivity of the hot-cathode transfer standards (spinning rotor gauges explicitly account for the gas temperature) so that individual laboratory results can be corrected to a common temperature.     

变频器在暖通空调行业中的应用

本文提出中央空调系统的一种变频调速改造方案，介绍了该系统的结构组成及运行原理，对系统各部分的作用进行了讨论。