Introduction: Over the last decades, various methods have been investigated for preschool screening for amblyogenic ametropia. The SureSight is a new hand-held wavefront-analyzing autorefractor designed for screening.
Methods: A total of 338 children (3 1/2 - 4 1/2 years-old) were examined in their kindergartens without cycloplegia using the new instrument. Of these, 56 had a cycloplegic retinoscopy as a reference measurement. Hyperopia > or =3 dpt, myopia > or =1 dpt, astigmatism > or =1 dpt and anisometropia > or =1 dpt were considered amblyogenic ametropia.
Results: Testability was 99.4%. Accuracy was high for cylinder power and axis but poor for the spherical equivalent. Sensitivity was 41% for the detection of amblyogenic hyperopia, 95% for astigmatism and 75% for anisometropia, with specificity values of 92, 79 and 73%.
Conclusion: The high testability and accuracy for cylinder power and axis are the strong points. The poor accuracy for the spherical equivalent is probably caused by the lack of cycloplegia. At present, non-cycloplegic autorefractor screening cannot be recommended due to the low specificity. Our findings support the advice that objective refraction in childhood must be performed with cycloplegia.
The drivetrain is an essential component of the diesel firefighting pump system, affecting the engine's operating mode, power, economy, and environment. This study proposes a process to design and optimize the transmission ratio and working load of the diesel firefighting pump system. AVL BOOST software was used to model the 6-cylinder diesel engine and analyze the performance characteristics at its partial loads as parameters for finding the optimal transmission ratio of the drivetrain.
Aim: To investigate the effect of astigmatism and spherical equivalent (SE) correction on contrast sensitivity (CS).
Methods: In this cross-sectional study, 103 visually normal subjects aged 18 to 36y with bilateral regular astigmatism in range of 1.00 diopter cylinder (DC) to 4.
The hydraulic support pushing mechanism is the primary equipment utilized in coal mine backfill operations, playing a crucial role in enhancing filling efficiency, ensuring a stable filling body, and managing gob safety. This paper focuses on analyzing the dynamic model and the interrelationship of the hydraulic cylinder, which serves as the power source for the pushing mechanism. To address the intricate coupling effects arising from the hydraulic cylinders and the displacement-force induced by the shared pump, this study employs feedforward compensation for decoupling analysis.
This paper presents an experimentally based study aimed at assessing the viability of employing a commercial energy harvester to develop a self-powered end-stroke and speed sensor for pneumatic cylinders. An energy-harvesting device was integrated into a cylinder end-cap to recover energy from the piston impact at the end of the stroke. The recovered energy powers a radio transmitter that communicates the reach of the end-stroke.
Due to the restrictions of the diesel engine emissions and the massive demand of energy, the fossil diesel fuel has been consumed quickly and the resources cannot suffice the demand. Alternative fuels that include bio alcohols, hydrogen and biodiesel can make up the diesel fuel depletion. Biodiesel is convenient for diesel engine operation due to its properties like fossil diesel properties.
