影响加工中心加工精度的因素

加工中心是高效自动化设备，为了充分利用机床的高效率、高精度、高自动化等特点，所以要考虑和了解影响加工中心加工精度的因素。     

Measurement of uncertainty in peptide molecular weight determination using size-exclusion chromatography with multi-angle laser light-scattering detection and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

The molecular weight of biopolymers such as peptides or proteins is vital information for understanding their physical/chemical properties. The matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and size-exclusion chromotography-multi-angle laser light scattering (SEC-MALLS) techniques each with its advantages and limitations were used for molecular weight determination of the SPf66 peptide. The precision of each method was studied using a two-factor fully-nested design with all the analyses performed by the same operator on a single instrument. The overall precision corresponded to the time-different intermediate precision (i.e. time and repeatability conditions). In the case of SEC-MALLS, all potential uncertainty components were carefully evaluated in an Ishikawa diagram, then included and mathematically combined with the uncertainty arising from the accuracy assessment to provide the overall uncertainty. In this case, the refractive-index increment with solute concentration value (dn/dc) provided the most significant contribution to the combined uncertainty. A method for its quantitation is proposed. The accuracy of method B (SEC-MALLS) against reference method A (MALDI-TOF-MS) was assessed using the interval testing hypothesis to limit the risk of unacceptable bias. The results indicate that the bias of B is higher than the limit established at 5%, and is therefore not traceable to A under the studied conditions.     

Estimation of the Common Mean of a Bivariate Normal Population

In this paper we discuss the problem of estimating the common mean of a bivariate normal population based on paired data as well as data on one of the marginals. Two double sampling schemes with the second stage sampling being either a simple random sampling (SRS) or a ranked set sampling (RSS) are considered. Two common mean estimators are proposed. It is found that under normality, the proposed RSS common mean estimator is always superior to the proposed SRS common mean estimator and other existing estimators such as the RSS regression estimator proposed by Yu and Lam (1997, Biometrics, 53, 1070–1080). The problem of estimating the mean Reid Vapor Pressure (RVP) of regular gasoline based on field and laboratory data is considered.     

具有白指数律重合性的GM(1,1)模型

通过分析 GM( 1 ,1 )建模机理 ,找出了 GM( 1 ,1 )模型不具有白指数律重合性的原因 ,并在此基础上 ,提出了建立 GM( 1 ,1 )模型的新方法 .新方法克服了原方法不具有白指数律重合性的缺陷 ,突破了 | a|较大时GM( 1 ,1 )模型不能应用的禁区 ,提高了建模的精度 .     

FORTRAN语言双精度运算的扩展应用

本文利用ＦＯＲＴＲＡＮ语言中不同类型变量的性质及数运算的特点，讨论了一种能将双精度实数运算扩展到整数运算中的方法，使整数运算也能得到接近双精度实数所具有的有效位数的整型结果。     

基于动态自适应t分布变异的人群搜索算法

针对人群搜索算法在进化后期大量个体聚集局部最优时,易陷入局部最优,搜索精度低的缺陷,提出一种基于t分布变异的人群搜索算法.算法使用动态自适应方式确定变异步长,引入t分布变异算子以融合柯西变异和高斯变异的优点,促进算法在进化早期具备良好的全局探索能力,在进化后期收获较强的局部开发能力,增加种群的多样性;采用边界缓冲墙策略处理越界问题,避免越界个体聚集在边界值上的缺陷.实验结果表明,算法比基本人群搜索算法具有更高的寻优精度和收敛速度,是一种有效的算法.     

无刷直流力矩电机系统的自适应扰动力矩补偿研究

陀螺漂移测试转台无刷直流力矩电机系统中存在波动力矩和负载力矩振动，这严重地影响了转台速率平稳度。为提高转台速率状态位置跟踪精度，设计了一种自适应补偿方法。该方法包含一个参自适应律和等效PID控制律，它利用前馈补偿原理，来估计电机中未知参数以及波动力矩和负载力矩参数并给与补偿。该自适应补偿方法保证了闭环系统全局稳定性和对期望位置信号的渐进跟踪。仿真结果证明：该方法有效地提高了转台速率状态跟踪精度。     

运动控制的数字随动系统

介绍了采用数字随动系统解决模拟伺服回路的设计技术，即选用智能化运动控制处理器用于无刷或有刷直流电动机控制。这种技术具有实时采集，操作简单，可靠性高，精度高等优点，在导航系统、雷达系统、火炮系统、汽车等领域具有广阔的发展前景。     

滤池大阻力配水系统改造的理论与实践

提出了一种对传统滤池支母管穿孔大阻力配水系统改造的理论和方法，并在工程应用中得到了确认     

The Development of Appropriate Upscaling Procedures

Permeability upscaling should be carried out with careful attention to the nature of rock heterogeneities. While there are many large-scale features which must be taken into account, there are also important heterogeneities at the small-scale. Many sedimentary structures contain laminae at the mm–cm scale, and beds at the m-scale, which give rise to strong contrasts in permeability. We use a 2D model derived from a photo-panel of an aeolian outcrop, along with permeability measurements from a North Sea oil field, to demonstrate the effects of small-scale heterogeneity. This model is similar in size to a typical cell of a reservoir geological model. We take imaginary probe and core plug measurements from the model, average them, and compare these with the effective permeability for the model computed from a finite difference flow calculation. Although this procedure is standard practice, we show that it can lead to biased estimates of the permeabilities used in flow simulation. As an alternative we suggest using models of representative beds, and performing flow simulation to calculate effective permeabilities for both single-phase and two-phase flow.