Demonstration of software programs for estimating multilevel measurement model parameters

A brief overview of the relevant parameterizations of the Rasch measurement model will first be provided. Next, the use of five different hierarchical linear modeling software programs (SAS, MLWIN, S-PLUS, R and HLM) using a heuristic data set will be demonstrated. For each program, researchers will be offered: 1) instructions describing the way to set up data sets, as well as 2) directions for running each program, 3) guidelines to assist with the appropriate interpretation of the output. Last, testing of the local independence assumption will be discussed. All data and code for each of the models run in this analysis may be downloaded from the website: http://www.hlm-online.com/papers/mmmpaper.htm/.     

Microprocessor controlled tape motion

The capstan control system of a high performance digital tape drive starts and stops tape with accelerations of about 500 g's. A microprocessor based control system is now being implemented on STC's 4500 Tape Systems to attain accurate tape speed control with little high frequency variation. Improvements made possible by the processor include controlling rate of change of motor current and drastically reducing start current when a "GO" command is received during a decelerate operation to avoid exciting a torsional resonance. Other improvements are mode-controlled digital error integration for long term accuracy and stop-lock stability enhancement by digital-gain switching.     

旋转平台绝对运动信息测量系统

针对当前旋转平台输出的运动信息没有时间刻度问题,设计一种带有GPS时间的运动信息测量系统。采用单片机STM32F103ZET6作为测量系统的主控单元,一方面通过串口采集GPS接收机模块提供的时间信息,另一方面运用单片机采集旋转平台上增量式光电编码器输出的脉冲信息,并实现两类信息的融合、存储;最后对系统测量精度从时间信息与运动信息两方面进行分析、优化与测试验证。测试表明:系统采用8 MHz无源晶振时,时间信息测量误差在±20μs以内;转台转速为1 r/s,半径为1 m,编码器光栅线数为10 000线时,该系统为转台提供的位移精度优于0.1 mm,满足测试应用需求。     

A new method for estimating subject specific body segment parameters using motion tracking data

Current segment inertial parameter estimation methods can be categorised as either regression, geometric or mass scanning based. Regression methods estimate segment parameters by developing regression equations using cadaver or live subject data. Geometric based methods model body segments as basic geometric shapes and calculate segment parameters assuming uniform density throughout the volume. Mass scanning methods also assume uniform density, but calculate segment shape and volume from mass scanning measurements. The first category does not yield subject specific segment parameters. The other two categories require time-consuming segment measurements and uniform density assumptions. This paper presents a new method for estimating subject specific body segment parameters that utilises work and energy equations and only requires kinematic and kinetic data from a standard walking trial. A preliminary evaluation of this method has been performed and results were comparable to current anthropometric data and average values obtained from mass scanning technology.     

Gas analysis measurement information system

Translated from Izmeritel'naya Tekhnika, No. 8, pp. 67–69, August, 1992.     

4-aperture differential image motion monitor as a new approach for estimating atmospheric turbulence parameters

The present study aims to evaluate the possibility of simultaneous measurements of Fried parameter and atmospheric Zernike defocus by measuring defocus aberration with 4-aperture differential image motion monitor (DIMM) for a portable telescope. Based on the results, a relation was observed between the variances of the defocus aberration (4-aperture defocus) and Fried parameter for G-tilt and Z-tilt methods. In addition, the variance of the 4-aperture defocus was compared with those of the Zernike defocus and the conventional DIMM and the results indicated a linear relationship. Based on the telescope and 4-aperture specifications, the variance of the 4-aperture defocus was converted into the Zernike defocus or the DIMM variances. Finally, the ability of estimating atmospheric coherence time by measuring the variance of the Zernike defocus velocity or the sum of the variances of two astigmatisms velocities with 4-aperture DIMM was investigated.     

A system for the spectrally-weighted measurement of signal parameters

The software and implementation of a measuring system based on a personal computer for investigating spectral methods of measuring the parameters of harmonic and polyharmonic signals and for carrying out practical measurements are described.     

热声制冷机网络模型中回热器H矩阵参数的测量

对热声系统的网络模型中回热器H矩阵的参数进行了分析,提出了一种H矩阵参数的测量方法。通过实验对简单圆管的无源网络进行测量,与模拟值有较好的吻合,证明实验系统是可靠的。在改变压力和频率的条件下对有源的热声制冷机回热器进行了测量和分析,模拟的结果与测量值基本上一致,流放大系数与模拟的结果偏差较大。说明热声系统是复杂的非线性系统,在线性假设前提下的热声网络模型的模拟结果会存在一定的偏差,尤其在大振幅条件下需要对网络参数进行测量和辨识,通过对网络参数的修正提高模拟的准确性。     

Refinement indicators for estimating hydrogeologic parameters

We identify simultaneously the hydraulic transmissivity and the storage coefficient in a ground water flow governed by a linear parabolic equation. Both coefficients are assumed to be functions which are piecewise constant in space and constant in time. Therefore, the unknowns are the coefficient values as well as the geometry of the zones where these parameters are constant. The identification problem is formulated as the minimization of a misfit least-square function. Using refinement indicators, we refine the parameterization locally and iteratively. We distinguish the cases where the two parameters have the same parameterization or different parameterizations.     

Standard program for metrological validation of information measurement system software

Translated from Izmeritel'naya Tekhnika, No. 10, pp. 16–18, October, 1991.     

Methods for estimating Weibull parameters for brittle materials

A Monte Carlo simulation is used to obtain the statistical properties of the Weibull parameters estimated by the linear regression, weighted linear regression, maximum likelihood and moments methods, respectively. Results reveal that the estimated Weibull modulus is always biased, which has a much lower accuracy than the scale parameter. The mean square error is adopted as a criterion for the comparison of the estimation methods. It is shown that both the probability estimators and the weight factors have great effects on the estimation precision of the Weibull modulus. The weighted linear regression with a weight factor of W _i =3.3P _i −27.5[1−(1−P _i )^0.025] and a probability estimator of P _i =(i−0.3)/(n+0.4) gives the most accurate estimation for sample sizes of 9–52. The maximum likelihood method recommended for any sample size by previous authors, comes first only for sample sizes larger than or equal to 53; furthermore, it is less conservative than the regression methods, and hence results in a lower safety in reliability predictions.     

Microprocessor system for controlling household electronic equipment

We propose three variants for systems for controlling household heating devices. We consider the feasibility of using these systems in various household consumer services (for therapeutic purposes, security systems, etc.). Translated from Izmeritel’naya Tekhnika, No. 7, pp. 30–32, July, 1999.     

计量信息管理系统的开发与应用

根据现代计量管理方法和使用先进的计算机网络技术开发出计量信息管理系统,阐述了对计量工作实现计算机化管理的必要性、意义和作用,介绍了用于现代化企业的通用计量信息管理系统的结构、功能及应用情况.实践证明,计量工作的计算机管理减轻了计量部门对计量器具管理的劳动强度,实现了对全厂计量工作的优化管理.     

Microprocessor application to concrete crack depth measurement

This work investigates the possibility of utilizing the µp-8085 and its application to concrete crack depth evaluation. For the purpose of the nondestructive testing, ultrasonic pulses are of importance in assessing the quality of concrete as well as flaw detection and measurement. This will be useful in repairing concrete columns.     

New methods for estimating deformations in measurement of the linear parameters of precision parts in the nanometric range

New measurement methods and measurement instrumentation with resolution of 0.1 nm are developed that make it possible to achieve objective reliable estimation of the influence that deformations exert on the accuracy with which precision parts are monitored in the nanometric range and to determine the parameters of these deformations. Translated from Izmeritel’naya Tekhnika, No. 12, pp. 6–10, December, 2008.