The Experts below are selected from a list of 17163 Experts worldwide ranked by ideXlab platform
Nicola S. Logan - One of the best experts on this subject based on the ideXlab platform.
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Shape of the posterior vitreous Chamber in human emmetropia and myopia
Investigative Ophthalmology & Visual Science, 2013Co-Authors: Bernard Gilmartin, Manbir Nagra, Nicola S. LoganAbstract:PURPOSE: To compare posterior vitreous Chamber Shape in myopia to that in emmetropia. METHODS: Both eyes of 55 adult subjects were studied, 27 with emmetropia (mean spherical error [MSE] ≥ -0.55;
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Shape of the posterior vitreous Chamber in human emmetropia and myopia
Investigative Ophthalmology & Visual Science, 2013Co-Authors: Bernard Gilmartin, Manbir Nagra, Nicola S. LoganAbstract:PURPOSE: To compare posterior vitreous Chamber Shape in myopia to that in emmetropia. METHODS: Both eyes of 55 adult subjects were studied, 27 with emmetropia (mean spherical error [MSE] ≥ -0.55; <+0.75 D; mean +0.09 ± 0.36 D) and 28 with myopia (MSE -5.87 ± 2.31 D). Cycloplegic refraction was measured with a Shin Nippon autorefractor and anterior Chamber depth and axial length with a Zeiss IOLMaster. Posterior vitreous Chamber Shapes were determined from T2-weighted magnetic resonance imaging (3.0-T) using procedures previously reported by our laboratory. Three-dimensional surface model coordinates were assigned to nasal, temporal, superior, and inferior quadrants and plotted in two dimensions to illustrate the composite Shape of respective quadrants posterior to the second nodal point. Spherical analogues of Chamber Shape were constructed to compare relative sphericity between refractive groups and quadrants. RESULTS: Differences in Shape occurred in the region posterior to points of maximum globe width and were thus in general accord with an equatorial model of myopic expansion. Shape in emmetropia is categorized distinctly as that of an oblate ellipse and in myopia as an oblate ellipse of significantly less degree such that it approximates to a sphere. There was concordance between Shape and retinotopic projection of respective quadrants into right, left, superior, and inferior visual fields. CONCLUSIONS: Prolate ellipse posterior Chamber Shapes were rarely found in myopia, and we propose that spherical Shape in myopia may constitute a biomechanical limitation on further axial elongation. Synchronization of quadrant Shapes with retinotopic projection suggests that binocular growth is coordinated by processes that operate beyond the optic chiasm.
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Shape of the posterior vitreous Chamber in human emmetropia and myopia
Investigative ophthalmology & visual science, 2013Co-Authors: Bernard Gilmartin, Manbir Nagra, Nicola S. LoganAbstract:PURPOSE - To compare posterior vitreous Chamber Shape in myopia to that in emmetropia. METHODS - Both eyes of 55 adult subjects were studied, 27 with emmetropia (MSE =-0.55;
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Shape of the posterior vitreous Chamber in human emmetropia and myopia
Investigative Ophthalmology & Visual Science, 2013Co-Authors: Bernard Gilmartin, Manbir Nagra, Nicola S. LoganAbstract:PURPOSE - To compare posterior vitreous Chamber Shape in myopia to that in emmetropia. METHODS - Both eyes of 55 adult subjects were studied, 27 with emmetropia (MSE =-0.55; <+0.75D; mean +0.09 ±0.36D) and 28 with myopia (MSE -5.87 ±2.31D). Cycloplegic refraction was measured with a Shin Nippon autorefractor and anterior Chamber depth and axial length with a Zeiss IOLMaster. Posterior vitreous Chamber Shapes were determined from T2-weighted MRI (3-Tesla) using procedures previously reported by our laboratory. 3-D surface model coordinates were assigned to nasal, temporal, superior and inferior quadrants and plotted in 2-D to illustrate the composite Shape of respective quadrants posterior to the second nodal point. Spherical analogues of Chamber Shape were constructed to compare relative sphericity between refractive groups and quadrants. RESULTS - Differences in Shape occurred in the region posterior to points of maximum globe width and were thus in general accord with an equatorial model of myopic expansion. Shape in emmetropia is categorised distinctly as that of an oblate ellipse and in myopia as an oblate ellipse of significantly less degree such that it approximates to a sphere. There was concordance between Shape and retinotopic projection of respective quadrants into right, left, superior and inferior visual fields. CONCLUSIONS - The transition in Shape from oblate ellipse to sphere with axial elongation supports the hypothesis that myopia may be a consequence of equatorial restriction associated with biomechanical anomalies of the ciliary apparatus. The synchronisation of quadrant Shapes with retinotopic projection suggests that binocular growth is coordinated by processes that operate beyond the optic chiasm.
Z.a Jahmany - One of the best experts on this subject based on the ideXlab platform.
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Combustion in a spark-ignition engine
Applied Energy, 2000Co-Authors: Z.h Kodah, H.s Soliman, M Abu Qudais, Z.a JahmanyAbstract:This paper describes a simple analysis for the prediction of pressure within a spark ignition engine. This is done by modelling the combustion process using the Wieb function approach, which is an exponential function in the form y=1-e-axm, to calculate the rate of fuel burned. By careful selection of a and m, any spark ignition engine with any combustion Chamber Shape and any specified dimensions can be assessed by this model. The validity of the model has been tested by comparing the model results with those obtained from running the engine under the same operating conditions. The results obtained from the theoretical model when compared with those from the experimental ones show a good agreement. Also, the effects of the many operating conditions, such as compression ratio, engine speed, and spark timing have been studied.
Bernard Gilmartin - One of the best experts on this subject based on the ideXlab platform.
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Shape of the posterior vitreous Chamber in human emmetropia and myopia
Investigative Ophthalmology & Visual Science, 2013Co-Authors: Bernard Gilmartin, Manbir Nagra, Nicola S. LoganAbstract:PURPOSE: To compare posterior vitreous Chamber Shape in myopia to that in emmetropia. METHODS: Both eyes of 55 adult subjects were studied, 27 with emmetropia (mean spherical error [MSE] ≥ -0.55;
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Shape of the posterior vitreous Chamber in human emmetropia and myopia
Investigative Ophthalmology & Visual Science, 2013Co-Authors: Bernard Gilmartin, Manbir Nagra, Nicola S. LoganAbstract:PURPOSE: To compare posterior vitreous Chamber Shape in myopia to that in emmetropia. METHODS: Both eyes of 55 adult subjects were studied, 27 with emmetropia (mean spherical error [MSE] ≥ -0.55; <+0.75 D; mean +0.09 ± 0.36 D) and 28 with myopia (MSE -5.87 ± 2.31 D). Cycloplegic refraction was measured with a Shin Nippon autorefractor and anterior Chamber depth and axial length with a Zeiss IOLMaster. Posterior vitreous Chamber Shapes were determined from T2-weighted magnetic resonance imaging (3.0-T) using procedures previously reported by our laboratory. Three-dimensional surface model coordinates were assigned to nasal, temporal, superior, and inferior quadrants and plotted in two dimensions to illustrate the composite Shape of respective quadrants posterior to the second nodal point. Spherical analogues of Chamber Shape were constructed to compare relative sphericity between refractive groups and quadrants. RESULTS: Differences in Shape occurred in the region posterior to points of maximum globe width and were thus in general accord with an equatorial model of myopic expansion. Shape in emmetropia is categorized distinctly as that of an oblate ellipse and in myopia as an oblate ellipse of significantly less degree such that it approximates to a sphere. There was concordance between Shape and retinotopic projection of respective quadrants into right, left, superior, and inferior visual fields. CONCLUSIONS: Prolate ellipse posterior Chamber Shapes were rarely found in myopia, and we propose that spherical Shape in myopia may constitute a biomechanical limitation on further axial elongation. Synchronization of quadrant Shapes with retinotopic projection suggests that binocular growth is coordinated by processes that operate beyond the optic chiasm.
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Shape of the posterior vitreous Chamber in human emmetropia and myopia
Investigative ophthalmology & visual science, 2013Co-Authors: Bernard Gilmartin, Manbir Nagra, Nicola S. LoganAbstract:PURPOSE - To compare posterior vitreous Chamber Shape in myopia to that in emmetropia. METHODS - Both eyes of 55 adult subjects were studied, 27 with emmetropia (MSE =-0.55;
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Shape of the posterior vitreous Chamber in human emmetropia and myopia
Investigative Ophthalmology & Visual Science, 2013Co-Authors: Bernard Gilmartin, Manbir Nagra, Nicola S. LoganAbstract:PURPOSE - To compare posterior vitreous Chamber Shape in myopia to that in emmetropia. METHODS - Both eyes of 55 adult subjects were studied, 27 with emmetropia (MSE =-0.55; <+0.75D; mean +0.09 ±0.36D) and 28 with myopia (MSE -5.87 ±2.31D). Cycloplegic refraction was measured with a Shin Nippon autorefractor and anterior Chamber depth and axial length with a Zeiss IOLMaster. Posterior vitreous Chamber Shapes were determined from T2-weighted MRI (3-Tesla) using procedures previously reported by our laboratory. 3-D surface model coordinates were assigned to nasal, temporal, superior and inferior quadrants and plotted in 2-D to illustrate the composite Shape of respective quadrants posterior to the second nodal point. Spherical analogues of Chamber Shape were constructed to compare relative sphericity between refractive groups and quadrants. RESULTS - Differences in Shape occurred in the region posterior to points of maximum globe width and were thus in general accord with an equatorial model of myopic expansion. Shape in emmetropia is categorised distinctly as that of an oblate ellipse and in myopia as an oblate ellipse of significantly less degree such that it approximates to a sphere. There was concordance between Shape and retinotopic projection of respective quadrants into right, left, superior and inferior visual fields. CONCLUSIONS - The transition in Shape from oblate ellipse to sphere with axial elongation supports the hypothesis that myopia may be a consequence of equatorial restriction associated with biomechanical anomalies of the ciliary apparatus. The synchronisation of quadrant Shapes with retinotopic projection suggests that binocular growth is coordinated by processes that operate beyond the optic chiasm.
Z.h Kodah - One of the best experts on this subject based on the ideXlab platform.
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Combustion in a spark-ignition engine
Applied Energy, 2000Co-Authors: Z.h Kodah, H.s Soliman, M Abu Qudais, Z.a JahmanyAbstract:This paper describes a simple analysis for the prediction of pressure within a spark ignition engine. This is done by modelling the combustion process using the Wieb function approach, which is an exponential function in the form y=1-e-axm, to calculate the rate of fuel burned. By careful selection of a and m, any spark ignition engine with any combustion Chamber Shape and any specified dimensions can be assessed by this model. The validity of the model has been tested by comparing the model results with those obtained from running the engine under the same operating conditions. The results obtained from the theoretical model when compared with those from the experimental ones show a good agreement. Also, the effects of the many operating conditions, such as compression ratio, engine speed, and spark timing have been studied.
Han Xu - One of the best experts on this subject based on the ideXlab platform.
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Analysis of pressure waves in the cone-type combustion Chamber under SI engine knock
Energy Conversion and Management, 2015Co-Authors: Han XuAbstract:For the internal-combustion engine, super knock produced by the engine downsizing technology induces severe oscillations in a combustion Chamber, which may damage the piston. In this work, 3D numerical simulation is used to study the propagation and reflection of pressure waves produced in the cone roof type combustion Chamber. Overpressure distribution of top piston surface is caught. Numerical simulation shows that the pressure waves are amplified in a special zone because of the Shape of the combustion Chamber, which induces the overpressure much higher than that in other zones. The numerical results are validated by the damaged pistons. It is found that the converged pressure waves could be the reason which causes damage in the local region of the piston under super knock. The results obtained in the study provide assistance in the design of combustion Chamber Shape in order to avoid piston destroyed by the pressure waves.