基于成分分析的铝电解质初晶温度软测量模型

为了准确获取铝电解质的初晶温度,引入软测量方法的思想,建立了以铝电解质成分的质量百分数为辅助变量,以Rerstreken公式和Rostum公式为基础的初晶温度软测量模型。结合铝电解过程,具体讨论了初晶温度软测量建模过程。分析了Rerstreken软测量模型和Rostum软测量模型的一致性,发现在相同情况下它们对初晶温度的估计值基本相等。试验结果表明,所提出的软测量模型能够准确地估算铝电解质初晶温度,估计值与参考值之间的最大绝对误差小于15℃。     

A nonintrusive flow measurement technique to validate the simulated laminar fluid flow in a packed container with vented walls

A nonintrusive flow measurement technique (particle image velocimetry) was used to determine the airflow field in a package with a container-to-product diameter ratio of less than 10. The complexity and uneven distribution of the measured flow field supported the requirement of a geometrical and mathematical model capable of describing the geometry and physics of flow within the package. Using novel computational fluid dynamics (CFD) codes, an accurate model of the packed structure was developed and the 3D Navier–Stokes equations were solved. A good agreement was obtained between experimental and predicted velocities. The detailed insight on the airflow pattern provided by the CFD analysis makes this approach an ideal tool to analyze the effect of different vent designs in the airflow field distribution in complex packaging systems.     

t检验法在涂料黏度比对试验中的应用研究

依据GB/T 1723—1993《涂料黏度测定法》,以大量的比对实践经验和试验数据为基础,以汽车用罩光清漆为例,论述了t检验法在汽车涂料黏度比对试验中的应用。评定方法适用于相似试验条件下的汽车用涂料黏度的比对试验。     

欠观测条件下的增量Kalman滤波方法

提出欠观测条件下增量Kalman滤波的概念和定义,建立增量Kalman滤波模型及其分析方法,给出主要的计算步骤。经典的Kalman滤波方法要求量测方程有较高精度,否则在递推过程中会产生较大误差。但是量测方程通常受环境因素影响较大,而且在许多实际情况(如深空探测)中不可能对所有的使用环境逐一校准量测方程。如果某量测方程没有在某一环境条件下进行验证或校准,那么在这一条件(称为欠观测条件)下使用该量测方程往往会产生未知的系统误差,从而导致较大的Kalman滤波误差。提出的欠观测条件下增量Kalman滤波方法能够成功消除这种未知的系统误差,大大提高Kalman滤波的精度。该方法计算简单,便于工程应用。     

Measuring large 3D structures using four portable tracking laser interferometers

A new concept that allows measuring 1D–3D objects in the range of several centimeters to 5 m × 5 m × 5 m is presented. In general terms the concept can be seen as a task specific correction of geometrical errors of coordinate measuring machines (CMMs). The developed system comprises a commercial CMM, its measurement and its evaluation software and a set of at least four high accurate tracking laser interferometers. The CMM is simply used as a mover which allows to capture points on the surface of a measuring object. In parallel the tracking laser interferometers follow a retro-reflector located close to the stylus tip of the tactile probe of the CMM. Based on a multi-lateration algorithm 3D-positions are calculated from the measured interferometric distances. Finally, two sets of coordinates emerged, namely, one by the CMM and the second from the metrological frame of the tracking laser interferometers. The interferometrically measured positions are usually more precise than the positions measured by the CMM. This is due to the high accuracy of the interferometric system and also due to the fact that the measurement positions are taken in a manner which almost avoids Abbe errors. Because of that, the measurement positions of the CMM are substituted with the more accurate measurement points calculated from distance measurements of the tracking interferometers. The position coordinates thus obtained are used for the further computerized evaluations, which yield the geometric parameters of the object measured. First measurements under laboratory condition show very promising results. It has been demonstrated that the concept is suitable for the high precision calibration of large workpieces with small tolerances, for instance, for the calibration of large gears for the windmill industry.     

The inertial technology based 3-dimensional information measurement system for underground pipeline

Underground pipeline industry is developing at a very high speed and it is playing an increasingly important role in modem world. However, how to make a precise 3-dimensional survey of underground pipelines becomes a focused issue. Current survey methods have several disadvantages, such as limited depth, sensitivity to electrical-magnetic disturbances, low generality and poor manipulability. Inertial technology is an autonomic, anti-disturbance and high accurate positioning method which has been widely used in navigation systems. An inertial technology based underground pipeline survey system is designed in this paper. Firstly, basic principles including 3-dimensional dead reckoning, pitch and yaw angle measurement and a special survey procedure are introduced. Secondly, the system is structured and its software is designed. Thirdly, several multi-information fusion methods are used to eliminate certain sensors’ disadvantages and promote the system’s precision. Finally, a series of field tests are introduced to verify the system.     

A self-calibrating instrument current transformer

This paper presents the development of a self-calibrating transformer for using as a primary standard in the Uruguayan National Metrology Institute. Nominal ratios go from 5 A/5 A to 2000 A/5 A. The primary windings are divided in groups to allow different ratios by changing their combinations in series–parallel connections, so that the errors remain the same. In ratio 1 (5 A/5 A) the transformer can be calibrated without any external standard, and a step-up procedure is proposed. Low errors are achieved by using a modified zero-flux technique.     

Simultaneous measurement of CO and CO2 at elevated temperatures by diode laser wavelength modulated spectroscopy

One single semiconductor distributed-feedback (DFB) laser is used to demonstrate the possibility of simultaneous measurements of CO and CO₂ at elevated temperatures. Wavelength modulation spectroscopy with second-harmonic detection is used to improve the detection sensitivity and accuracy. The concentrations of CO and CO₂ are determined from the WMS-1-normalized absorption-based WMS-2f signal peak heights of a proper line pair of CO and CO₂ near 6357.814 cm⁻¹ and 6357.312 cm⁻¹, which are selected using some line-selection criterions for the target temperature range of 300–1000 K. The CO and CO₂ concentrations measurements are within 2.86% and 2.69% of the expected values over the tested temperature range 300–1000 K. The minimum detectable concentrations of CO and CO₂ at 1000 K are 250 ppm m and 280 ppm m respectively.     

High frequency comparison with thermoelectric power sensors between INRIM and NMC

This paper describes the bilateral comparison carried out by two National Metrology Institutes, NMC from Singapore and INRIM from Italy. The subject of the comparison concerns the calibration of a new type of coaxial power sensors fitted with type N (up to 18 GHz) and 3.5 mm (up to 26.5 GHz) connector. This is the first international comparison of this kind in which the transfer standards are based on indirect heating thermocouples. Results show that the introduction of this type of transfer standard and the update of the measurement techniques of both institutes allowed a general reduction of the uncertainty with respect to that declared in the last Key Comparison in the field.     

3-PSS并联机构正解及其在坐标测量机中的应用

针对传统坐标测量机和关节臂测量机存在的技术局限,基于3-PSS并联机构原理,提出了只需一只长光栅、一条精密导轨即可实现三维空间精密测量的坐标测量机,并研究了测量系统的测量模型、测量误差模型及并联机构误差平均效应.根据并联机构基本理论建立了测量机的六杆测量模型,在此基础上进行了杆长制造、装配误差和光栅读数误差的理论分析.然后,从理论上展示和说明了并联机构存在误差平均效应的数学本质和依据.最后,介绍了样机的设计及制造,并给出初步的实验结果.在没有进行误差修正和系统标定的前提下,该样机在X,Y,Z3个坐标方向上的测量误差分别为0.029 mm,0.045 mm和0.058 mm.得到的结果可指导新样机的优化设计.