Measurement of productivity index with dynamic DEA

Fare, Grosskopf, Norris and Zhang developed a non-parametric productivity index, Malmquist index, using data envelopment analysis (DEA). The Malmquist index is a measure of productivity progress (regress) and it can be decomposed to different components such as 'efficiency catch-up' and 'technology change'. However, Malmquist index and its components are based on two period of time which can capture only a part of the impact of investment in long-lived assets. The effects of lags in the investment process on the capital stock have been ignored in the current model of Malmquist index. This paper extends the recent dynamic DEA model introduced by Emrouznejad and Thanassoulis and Emrouznejad for dynamic Malmquist index. This paper shows that the dynamic productivity results for Organisation for Economic Cooperation and Development countries should reflect reality better than those based on conventional model.

Continuous measurement of accommodation in human factor applications

It has long been sought to measure ocular accommodation continuously in human factor applications such as driving or flying. Open-field autorefractors such as the Canon R-1 could be converted to allow continuous, objective recording, but steady eye fixation and head immobilisation were essential for the measurements to be valid. Image analysis techniques utilised by newer open-view autorefractors such as the Shin-Nippon SRW-5000 are more tolerant to head and eye movements, but perhaps the technique with the greatest potential for the measurement of accommodation in human factor applications is photoretinoscopy. This paper examines the development of techniques for high temporal measurements of accommodation and reports on the tolerance of one such recent commercial instrument, the PowerRefractor (PlusOptiX). The instrument was found to be tolerant to eye movements from the optical axis of the instrument (∼0.50 DS change in apparent accommodation with gaze 25° eccentric to the optical axis), longitudinal head movement (<0.25 DS from 8 cm towards and 20 cm away from the correct photorefractor to eye distance) and changes in background illuminance (<0.25 DS from 0.5 to 20 cd m-2 target luminance). The PowerRefractor also quantifies the direction of gaze and pupil size, but is unable to take measurements with small pupils <3.7 ±1.0 mm. © 2002 The College of Optometrists.

Measurement of project management performance:a case study in the Indian oil industry

Eight steps for projectizing continuous improvement to deliver desired change

Simultaneous strain and temperature measurement of advanced 3-D braided composite materials using an improved EFPI/FBG system

Simultaneous strain and temperature measurement for advanced 3-D braided composite materials using fibre-optic sensor technology is demonstrated, for the first time. These advanced 3-D braided composites can virtually eliminate the most serious problem of delamination for conventional composites. A tandem in-fibre Bragg-grating (FBG)/extrinsic Fabry-Perot interferometric sensor (EFPI) system with improved accuracy has been used to facilitate simultaneous temperature and strain measurement in this work. The non-symmetric distortion of the optical spectrum of the FBG, due to the combination of the FBG and the EFPI, is observed for the first time. Experimental and theoretical studies indicate that this type of distortion can affect the measurement accuracy seriously and it is mainly caused by the modulation of the periodic output of the EFPI. A simple method has been demonstrated to improve the accuracy for detection of the wavelength-shift of the FBG induced by temperature change. A strain accuracy of ∼ ±20 με and a temperature accuracy of ∼ ±1 °C have been achieved, which can meet the requirements for practical applications of 3-D braided composites. © 2002 Elsevier Science Ltd. All rights reserved.

Nondestructive measurement of water content and moisture migration of unsaturated red clays in South China

To reveal the moisture migration mechanism of the unsaturated red clays, which are sensitive to water content change and widely distributed in South China, and then rationally use them as a filling material for highway embankments, a method to measure the water content of red clay cylinders using X-ray computed tomography (CT) was proposed and verified. Then, studies on the moisture migrations in the red clays under the rainfall and ground water level were performed at different degrees of compaction. The results show that the relationship between dry density, water content, and CT value determined from X-ray CT tests can be used to nondestructively measure the water content of red clay cylinders at different migration time, which avoids the error reduced by the sample-to-sample variation. The rainfall, ground water level, and degree of compaction are factors that can significantly affect the moisture migration distance and migration rate. Some techniques, such as lowering groundwater table and increasing degree of compaction of the red clays, can be used to prevent or delay the moisture migration in highway embankments filled with red clays.

The measurement of intraocular pressure over positive soft contact lenses by rebound tonometry

Purpose - To investigate if the accuracy of intraocular pressure (IOP) measurements using rebound tonometry over disposable hydrogel (etafilcon A) contact lenses (CL) is affected by the positive power of the CLs. Methods - The experimental group comprised 26 subjects, (8 male, 18 female). IOP measurements were undertaken on the subjects’ right eyes in random order using a Rebound Tonometer (ICare). The CLs had powers of +2.00 D and +6.00 D. Measurements were taken over each contact lens and also before and after the CLs had been worn. Results - The IOP measure obtained with both CLs was significantly lower compared to the value without CLs (t test; p < 0.001) but no significant difference was found between the two powers of CLs. Conclusions - Rebound tonometry over positive hydrogel CLs leads to a certain degree of IOP underestimation. This result did not change for the two positive lenses used in the experiment, despite their large difference in power and therefore in lens thickness. Optometrists should bear this in mind when measuring IOP with the rebound tonometer over plus power contact lenses.