Clinical Characteristics of Intermittent Esotropia

Purpose: To evaluate clinical findings and surgical outcomes of intermittent esotropia.Methods: We retrospectively reviewed the medical records of 23 patients (aged 9-42 years) who presented with intermittent esotropia between January 2007 and December 2020. We analyzed the age at onset, angle of deviation, presence of symptomatic diplopia, fusional state, near stereoacuity, and surgical results.Results: The mean age at onset was 19.9 ± 8.0 years and mean duration of esodeviation was 23.4 ± 27.1 months. Mean follow-up time was 13.0 ± 15.6 months. All patients except three had symptomatic diplopia, and 78.3% showed intermittent diplopia. Mean angles of deviation were 21.6 ± 10.3 prism diopters (PD) at distance and 20.2 ± 10.4 PD at near. Twenty-one patients (91.3%) were myopia. No patients had amblyopia and one had dissociated vertical deviation. On Worth’s four-dot test, five patients (21.7%) showed diplopia and four showed suppression at both distance and near. The other patients showed fusion at near or distance. Eleven patients underwent surgical correction. At the final examination, all patients achieved successful motor alignment and fusion with resolution of diplopia. Only two patients (18.2%) achieved normal 60 arcsec stereopsis, and six attained subnormal stereopsis.Conclusions: The main symptom of intermittent esotropia was diplopia. Surgical treatment was effective in achieving good postoperative motor alignment and fusion. However, successful motor alignment did not guarantee recovery of fine stereopsis.

A comparative study into the effects of pre and post catalyst exhaust gas recirculation on the onset of knock

Exhaust gas recirculation (EGR) is proven as a valuable technology for controlling knock whilst maintaining lambda one operation, and is also capable of providing efficiency gains at low load. Despite this few studies in the literature address the question of EGR composition effects, namely whether the EGR gas is sourced from before or after the catalyst, and this remains an area which is often overlooked whilst investigating EGR performance. This paper demonstrates a novel method combining experiment air-path emulation and in-depth data processes to compare the effect of EGR catalysis on the angle of knock onset in a 1L GDI engine. Since initial temperature and pressure have a significant impact on knocking behaviour, an artificial boosting rig replaced the turbomachinery. This enabled fine control over the engine boundary conditions to ensure parity between the catalysed and un-catalysed cases. To overcome the difficulty of comparing stochastic phenomena in an inherently variable dataset, a pairing method was combined with Shahlari and Ghandhi’s angle of knock onset determination method to assess the effects of EGR composition on knock onset for EGR rates ranging from 9% to 18%. The air path emulation system stabilised the engine combustion to provide a suitably rich dataset for analysing knock using the pairing method. Catalysed EGR improved the mean knock onset angle by 0.55 CAD, but due to the inherent variability in cylinder pressure data this only equated to a 58.3% chance of a later knock onset angle for catalysed EGR in any given pair of comparative cycles.

Prediction of Dynamic Stall Onset for Oscillatory Low-Speed Airfoils

This research presents some common features of oscillatory airfoils, and the method for indicating dynamic stall onset for the unsteady process. Under deep stall conditions, the stall-onset angle in oscillation is independent of the mean angle of the oscillatory motion, and by combining the reduced frequency and the amplitude of the oscillatory motion, the equivalent reduced pitch rate is an analog of this motion to the constant reduced pitch rate of the ramp-up motion. By correlating with the measured data, and with the ramp-up results, the equivalent reduced pitch rate can be defined as a representation for the oscillatory motion. Accordingly, the triple-parameter problem of an oscillation (mean angle, reduced frequency, and amplitude) degrades into the single-parameter problem (equivalent reduced pitch rate). Based on these foundations, an extension of the stall-onset criterion is then made for oscillatory airfoils: a method of extracting the stall-onset parameters directly from oscillatory test data, and an indication of stall onset for the oscillatory airfoils. The results from the new proposed method have shown the consistency with the data of Glasgow University and the public data.