等离子弧焊自动控制器的研究

本文介绍了一种小孔法等离子弧焊双参数微机控制器。它以小孔电压作为检测对象，以焊接电流和焊接速度作为被控对象，采用微机进行实时控制，具有灵敏度高、灵活性好、结构简单、与焊机控制部分联机自动化程度高、操作方便等优点。工艺考核表明：控制系统允许焊接规范参数有较大的波动范围，并能降低对工件装配质量的要求。     

双参数弹性地基板的动力问题

针对目前带自由边的双参数弹性地基板的边界条件及基本方程在使用上的混乱情况,为了板与地基动力相互作用理论的严密性和计算的可靠性,将板和地基作为一个总系统,利用H am ilton动力变分原理,重新系统地审视了双参数弹性地基上板动力问题的基本理论,给出了地基附加质量影响的明确计算公式,建立了考虑地基附加质量影响的基本方程和边界条件,并对边界条件的简化进行了讨论.所得的结果还可推广到位于层状地基上的板的分析.     

定数截尾下双参数指数分布位置参数的统计推断

通过逆矩法的估计方法,得到了定数截尾下双参数指数分布E（μ,A）中位置参数μ的逆估计量。模拟结果表明逆矩法估计量是可行的。同时,也得到构造位置参数区间估计的方法。     

Estimation of IRT graded response models: Limited versus full information methods.

The performance of parameter estimates and standard errors in estimating F. Samejima’s graded response model was examined across 324 conditions. Full information maximum likelihood (FIML) was compared with a 3-stage estimator for categorical item factor analysis (CIFA) when the unweighted least squares method was used in CIFA’s third stage. CIFA is much faster in estimating multidimensional models, particularly with correlated dimensions. Overall, CIFA yields slightly more accurate parameter estimates, and FIML yields slightly more accurate standard errors. Yet, across most conditions, differences between methods are negligible. FIML is the best election in small sample sizes (200 observations). CIFA is the best election in larger samples (on computational grounds). Both methods failed in a number of conditions, most of which involved 200 observations, few indicators per dimension, highly skewed items, or low factor loadings. These conditions are to be avoided in applications. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

两指标时间序列预报的一类方法

本文在平稳和非平稳情形,构造了两指标时间序列的一类预报方法。在平稳条件下构造了两指标 AR 过程的最佳线性预报。在非平稳情形,利用单指标时间序列的新息预报思想,首先将非平稳过程的自回归系数看作是一个新的两指标多维平稳过程加以预报,然后再对非平稳过程本身做最佳线性预报。     

高液限土路基掺沙改良路用特性试验

为了研究高液限土路基掺沙改良的长期水稳定性和强度特性,以最大干密度、界限含水率、浸水CBR强度值作为路用特性分析的控制参数,进行室内试验和现场试验。依据不同掺沙量和压实度条件下各控制参数的变化规律确定最优掺沙比;在最优掺沙条件下,进一步分析路用水稳定性与施工控制参数,即含水率、压实度、击实功的变化规律,获得水稳定性和强度兼顾的施工参数最佳组合。试验表明,以空气率和饱和度作为路基施工质量检测双指标控制方法,可以弥补现行规范仅以压实度作为单一质量评价标准的不足。     

基于相位比较的学生宿舍限电装置研究与应用

学生宿舍用电的安全、科学管理是高校后勤部门的重要任务.基于安全和规范的原则,宿台在不同的时间段有不同的用电限制.本文设计的限电装置能够根据具体要求,通过判断电路负载的电压电流相位变化,来识别用电器的类型,达到全天限制发热性违禁电器和夜晚限制计算机等开关性负载的目的,实现安全、可靠、人性化的学生宿合用电管理.     

Supporting students' motivation, engagement, and learning during an uninteresting activity.

The present study examined the capacity of 2 different theoretical models of motivation to explain why an externally provided rationale often supports students' motivation, engagement, and learning during relatively uninteresting learning activities. One hundred thirty-six undergraduates (108 women, 28 men) worked on an uninteresting 20-min lesson after either receiving or not receiving a rationale. Participants who received the rationale showed greater identified regulation, interest-enhancing strategies, behavioral engagement, and conceptual learning. Structural equation modeling was used to test 3 alternative explanatory models to understand why the rationale produced these benefits--an identified regulation model based on self-determination theory, an interest regulation model based on interest-enhancing strategies research, and an additive model that integrated both models. The data fit all 3 models; however, only the model that included rationale-enhanced identified regulation uniquely fostered students' engagement and hence their learning. Findings highlight the role that externally provided rationales can play in helping students generate the autonomous motivation they need to engage constructively in and learn from uninteresting, but personally important, lessons. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

雷莫方程及其应用

指出了威里时间平均方程在确定声波孔隙度中存在的一些不足，介绍了以实测资料为基础的雷莫方程及其改进算式，并给出了雷莫方程的计算方法及参数选取，为了核算孤岛油田的原始石油储量，计算现有的剩余储量，达到控水稳油的目的。使用雷莫方程的改进算子对弧岛油田５００多口井的测井资料进行了数据处理，求取了地层孔隙度。     

用Excel函数提取身份证数据的初探

日常大量的表格都需要填写人的身份证号码、年龄、性别、出生日期等参数。Excel是较常用的一种办公软件。能否用Excel的内置函数,在输入身份证的号码后,自动将年龄、性别、出生日期的参数计算出来。文中主要探讨对现在使用 15位、18 位、18 位最末位是 X三种身份证类型的公式设计。