Automated keratometry in routine cataract surgery: comparison of Scheimpflug and conventional values.
ABSTRACT To compare the mean keratometry (K) readings obtained with a conventional automated keratometer (IOLMaster) and a Scheimpflug keratometer (Pentacam) in eyes having preoperative assessment for routine cataract surgery.
Epsom and St. Helier University Hospitals, London, United Kingdom.
Evaluation of diagnostic technology.
Mean K values were obtained with the conventional and Scheimpflug keratometers. The following Scheimpflug readings were evaluated: anterior K, true net power, and Holladay equivalent K measured at 1.0 to 7.0 mm corneal diameters. Mean readings for each type of keratometry were compared. Bland-Altman plots were used to determine the 95% limits of agreement (LoA) for the conventional and Scheimpflug keratometers.
The mean conventional K was statistically significantly greater than the mean Scheimpflug K for true net power and equivalent K at 1.0 mm, 2.0 mm, 3.0 mm, and 4.0 mm corneal diameters. The mean conventional K was significantly less than the equivalent K at 5.0 mm, 6.0 mm, and 7.0 mm. The smallest mean difference was for equivalent K at 4.5 mm (0.02 diopters [D]). The smallest 95% LoA were -0.68 to 1.16 D (equivalent K at 5.0 mm) and -0.91 to 0.95 D (equivalent K at 4.5 mm).
Overall, the equivalent K at 4.5 mm had the closest match with the conventional K values. The degree of interdevice variability with the conventional keratometer was lowest for the equivalent K at 4.5 mm and 5.0 mm, although this variability would be sufficient to influence intraocular lens power selection.
Conference Proceeding: Three phases PWM d-q frame harmonics calculation[show abstract] [hide abstract]
ABSTRACT: This paper gives a modeling of a three phases PWM converter for two carriers used in industrial applications with analogue or digital control. The spectrum of these four types of configurations is calculated into the d-q frame which gives an easier interpretation of the harmonic components. Two calculations of possible unbalanced systems are presented with a validation by simulation, then an experimental validation through the current measurement of a synchronous machine is carried out.Power Electronic Drives and Energy Systems for Industrial Growth, 1998. Proceedings. 1998 International Conference on; 01/1999
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ABSTRACT: A summary of design specifications and operational data collected from February until August 1987 using the MINIDAS data-acquisition system are presented for a 300 kW peak power experimental PV plant aimed at demonstration and testing of components and systems, with emphasis on reliability, lifetime, maintenance, and operational problems. Recorded data are transferred to a PDP 11 computer system for statistical processing and presentation. The data show that the plant reached a maximum power of 310 kW on a very clean and cold day in April at a solar radiation of about 1020 W/m2. It is shown that the field arrangement produces a power rate per unit area of 77 Wp/m2/.01/1988;