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Senya Shlosman - One of the best experts on this subject based on the ideXlab platform.
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Extremal Cylinder Configurations I: Configuration $$C_{\mathfrak {m}}$$ C m
Discrete & Computational Geometry, 2020Co-Authors: Oleg Ogievetsky, Senya ShlosmanAbstract:We study the path $$\Gamma =\{ C_{6,x}\mid x\in [0,1]\}$$ Γ = { C 6 , x ∣ x ∈ [ 0 , 1 ] } in the moduli space of Configurations of six equal Cylinders touching the unit sphere. Among the Configurations $$C_{6,x}$$ C 6 , x is the record configuration $$C_{\mathfrak {m}}$$ C m of Ogievetsky and Shlosman (Discrete Comput Geom 2019, https://doi.org/10.1007/s00454-019-00064-3 ). We show that $$C_{\mathfrak {m}}$$ C m is a local sharp maximum of the distance function, so in particular the configuration $$C_{\mathfrak {m}}$$ C m is not only unlockable but rigid. We show that if $${(1 + x) (1 + 3 x)}/{3}$$ ( 1 + x ) ( 1 + 3 x ) / 3 is a rational number but not a square of a rational number, the configuration $$C_{6,x}$$ C 6 , x has some hidden symmetries, part of which we explain.
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extremal Cylinder Configurations i configuration c_ mathfrak m
Discrete and Computational Geometry, 2020Co-Authors: Oleg Ogievetsky, Senya ShlosmanAbstract:We study the path $$\Gamma =\{ C_{6,x}\mid x\in [0,1]\}$$ in the moduli space of Configurations of six equal Cylinders touching the unit sphere. Among the Configurations $$C_{6,x}$$ is the record configuration $$C_{\mathfrak {m}}$$ of Ogievetsky and Shlosman (Discrete Comput Geom 2019, https://doi.org/10.1007/s00454-019-00064-3 ). We show that $$C_{\mathfrak {m}}$$ is a local sharp maximum of the distance function, so in particular the configuration $$C_{\mathfrak {m}}$$ is not only unlockable but rigid. We show that if $${(1 + x) (1 + 3 x)}/{3}$$ is a rational number but not a square of a rational number, the configuration $$C_{6,x}$$ has some hidden symmetries, part of which we explain.
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Extremal Cylinder Configurations II: Configuration O6
Experimental Mathematics, 2019Co-Authors: Oleg Ogievetsky, Senya ShlosmanAbstract:AbstractWe study the octahedral configuration O6 [Kuperberg] of six equal Cylinders touching the unit sphere. We show that the configuration O6 is a local sharp maximum of the distance function. Th...
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Extremal Cylinder Configurations II: Configuration $O_6$
arXiv: Metric Geometry, 2019Co-Authors: Oleg Ogievetsky, Senya ShlosmanAbstract:We study the octahedral Configurations $O_6$ of six equal Cylinders touching the unit sphere. We show that the configuration $O_6$ is a local sharp maximum of the distance function. Thus it is not unlockable and, moreover, rigid.
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extremal Cylinder Configurations ii configuration o_6
arXiv: Metric Geometry, 2019Co-Authors: Oleg Ogievetsky, Senya ShlosmanAbstract:We study the octahedral Configurations $O_6$ of six equal Cylinders touching the unit sphere. We show that the configuration $O_6$ is a local sharp maximum of the distance function. Thus it is not unlockable and, moreover, rigid.
Oleg Ogievetsky - One of the best experts on this subject based on the ideXlab platform.
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Extremal Cylinder Configurations I: Configuration $$C_{\mathfrak {m}}$$ C m
Discrete & Computational Geometry, 2020Co-Authors: Oleg Ogievetsky, Senya ShlosmanAbstract:We study the path $$\Gamma =\{ C_{6,x}\mid x\in [0,1]\}$$ Γ = { C 6 , x ∣ x ∈ [ 0 , 1 ] } in the moduli space of Configurations of six equal Cylinders touching the unit sphere. Among the Configurations $$C_{6,x}$$ C 6 , x is the record configuration $$C_{\mathfrak {m}}$$ C m of Ogievetsky and Shlosman (Discrete Comput Geom 2019, https://doi.org/10.1007/s00454-019-00064-3 ). We show that $$C_{\mathfrak {m}}$$ C m is a local sharp maximum of the distance function, so in particular the configuration $$C_{\mathfrak {m}}$$ C m is not only unlockable but rigid. We show that if $${(1 + x) (1 + 3 x)}/{3}$$ ( 1 + x ) ( 1 + 3 x ) / 3 is a rational number but not a square of a rational number, the configuration $$C_{6,x}$$ C 6 , x has some hidden symmetries, part of which we explain.
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extremal Cylinder Configurations i configuration c_ mathfrak m
Discrete and Computational Geometry, 2020Co-Authors: Oleg Ogievetsky, Senya ShlosmanAbstract:We study the path $$\Gamma =\{ C_{6,x}\mid x\in [0,1]\}$$ in the moduli space of Configurations of six equal Cylinders touching the unit sphere. Among the Configurations $$C_{6,x}$$ is the record configuration $$C_{\mathfrak {m}}$$ of Ogievetsky and Shlosman (Discrete Comput Geom 2019, https://doi.org/10.1007/s00454-019-00064-3 ). We show that $$C_{\mathfrak {m}}$$ is a local sharp maximum of the distance function, so in particular the configuration $$C_{\mathfrak {m}}$$ is not only unlockable but rigid. We show that if $${(1 + x) (1 + 3 x)}/{3}$$ is a rational number but not a square of a rational number, the configuration $$C_{6,x}$$ has some hidden symmetries, part of which we explain.
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Extremal Cylinder Configurations II: Configuration O6
Experimental Mathematics, 2019Co-Authors: Oleg Ogievetsky, Senya ShlosmanAbstract:AbstractWe study the octahedral configuration O6 [Kuperberg] of six equal Cylinders touching the unit sphere. We show that the configuration O6 is a local sharp maximum of the distance function. Th...
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Extremal Cylinder Configurations II: Configuration $O_6$
arXiv: Metric Geometry, 2019Co-Authors: Oleg Ogievetsky, Senya ShlosmanAbstract:We study the octahedral Configurations $O_6$ of six equal Cylinders touching the unit sphere. We show that the configuration $O_6$ is a local sharp maximum of the distance function. Thus it is not unlockable and, moreover, rigid.
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extremal Cylinder Configurations ii configuration o_6
arXiv: Metric Geometry, 2019Co-Authors: Oleg Ogievetsky, Senya ShlosmanAbstract:We study the octahedral Configurations $O_6$ of six equal Cylinders touching the unit sphere. We show that the configuration $O_6$ is a local sharp maximum of the distance function. Thus it is not unlockable and, moreover, rigid.
S. A. Nada - One of the best experts on this subject based on the ideXlab platform.
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Slot/slots air jet impinging cooling of a Cylinder for different jets–Cylinder Configurations
Heat and Mass Transfer, 2006Co-Authors: S. A. NadaAbstract:Heat transfer characteristics of a slot/slots jet air impinging on a Cylinder have been experimentally investigated for two different orientations of slot/slots jet plan with respect to Cylinder axis. The experiments were carried out to study the effects of orientation of slot/slots jet plan with respect to Cylinder axis on the rate of heat transfer from the Cylinder. Two different jet–Cylinder Configurations were studied: (1) single slot jet aligned with Cylinder axis (slot length = Cylinder length), and (2) multiple slot jets equally spaces distributed orthogonal to Cylinder axis (each slot length = Cylinder diameter and sum of slots lengths = Cylinder length). For each configuration, parametric effects of Reynolds numbers ( Re ) ranging from 1,000 to 10,000, dimensionless slot widths ( W / d ) ranging from 0.125 to 0.5, and dimensionless slot orifice-to-Cylinder spacing ( Z / W ) ranging from 1 to 12 on local and average Nusselt numbers around Cylinder surface have been investigated. The results showed that: (1) cooling the Cylinder by multiple slots jets situated orthogonal to Cylinder axis gave more uniform surface temperature distributions and higher heat transfer rate than the case of cooling the Cylinder by single slot jet aligned with Cylinder axis, (2) for both Configurations the Nusselt number around the Cylinder increased with increasing Re and W / d , and (3) for both Configurations there was a certain Z / W in the range 4< Z / W
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slot slots air jet impinging cooling of a Cylinder for different jets Cylinder Configurations
Heat and Mass Transfer, 2006Co-Authors: S. A. NadaAbstract:Heat transfer characteristics of a slot/slots jet air impinging on a Cylinder have been experimentally investigated for two different orientations of slot/slots jet plan with respect to Cylinder axis. The experiments were carried out to study the effects of orientation of slot/slots jet plan with respect to Cylinder axis on the rate of heat transfer from the Cylinder. Two different jet–Cylinder Configurations were studied: (1) single slot jet aligned with Cylinder axis (slot length = Cylinder length), and (2) multiple slot jets equally spaces distributed orthogonal to Cylinder axis (each slot length = Cylinder diameter and sum of slots lengths = Cylinder length). For each configuration, parametric effects of Reynolds numbers (Re) ranging from 1,000 to 10,000, dimensionless slot widths (W/d) ranging from 0.125 to 0.5, and dimensionless slot orifice-to-Cylinder spacing (Z/W) ranging from 1 to 12 on local and average Nusselt numbers around Cylinder surface have been investigated. The results showed that: (1) cooling the Cylinder by multiple slots jets situated orthogonal to Cylinder axis gave more uniform surface temperature distributions and higher heat transfer rate than the case of cooling the Cylinder by single slot jet aligned with Cylinder axis, (2) for both Configurations the Nusselt number around the Cylinder increased with increasing Re and W/d, and (3) for both Configurations there was a certain Z/W in the range 4
stagnation and mean Nusselt number were maximum. Correlations for the mean Nusselt numbers around Cylinder surface have been presented for both Configurations. Comparisons between the correlations predictions and the present and other previous experimental data have been conducted.
L. Yang - One of the best experts on this subject based on the ideXlab platform.
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Steady energy deposition at Mach 5 for drag reduction
Shock Waves, 2013Co-Authors: E. Erdem, K. Kontis, L. YangAbstract:Experiments addressing the effect of energy deposition via arc discharge on $$15^\circ $$ half angle-truncated cone-Cylinder Configurations at Mach 5 flow were carried out. The arc discharge was accomplished using a setup that consisted of a power supply, a high voltage unit and tungsten electrodes. Discharge-on tests were compared to discharge-off tests to evaluate the net effect of the energy deposition. Flow visualisation revealed the presence of a heated wake downstream of the energy spot. Compression waves were observed on top of the wake of the heated channel, which were oscillatory in nature. The deposited energy of 7 W shows a repeatable influence on the measured drag force for all the models at close arc-to-nose distances.
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Steady energy deposition at Mach 5 for drag reduction
Shock Waves, 2013Co-Authors: E. Erdem, K. Kontis, L. YangAbstract:Experiments addressing the effect of energy deposition via arc discharge on $$15^\circ $$ half angle-truncated cone-Cylinder Configurations at Mach 5 flow were carried out. The arc discharge was accomplished using a setup that consisted of a power supply, a high voltage unit and tungsten electrodes. Discharge-on tests were compared to discharge-off tests to evaluate the net effect of the energy deposition. Flow visualisation revealed the presence of a heated wake downstream of the energy spot. Compression waves were observed on top of the wake of the heated channel, which were oscillatory in nature. The deposited energy of 7 W shows a repeatable influence on the measured drag force for all the models at close arc-to-nose distances.
I. A. Kovalev - One of the best experts on this subject based on the ideXlab platform.
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Development of High-Powered Steam Turbines by OAO NPO Central Research and Design Institute for Boilers and Turbines
Thermal Engineering, 2018Co-Authors: V. E. Mikhailov, L. A. Khomenok, I. A. KovalevAbstract:The article provides an overview of the developments by OAO NPO TsKTI aimed at improvement of components and assemblies of new-generation turbine plants for ultra-supercritical steam parameters to be installed at the power-generating facilities in service. The list of the assemblies under development includes Cylinder shells, the Cylinder’s flow paths and rotors, seals, bearings, and rotor cooling systems. The authors consider variants of the shafting–Cylinder Configurations for which advanced high-pressure and intermediate-pressure Cylinders with reactive blading and low-pressure Cylinders of conventional design and with counter-current steam flows are proposed and high-pressure rotors, which can increase the economic efficiency and reduce the overall turbine plant dimensions. Materials intended for the equipment components that operate at high temperatures and a steam cooling technique that allows the use of cheaper steel grades owing to the reduction in the metal’s working temperature are proposed. A new promising material for the bearing surfaces is described that enables the operation at higher unit pressures. The material was tested on a full-scale test bench at OAO NPO TsKTI and a turbine in operation. Ways of controlling the erosion of the blades in the moisture–steam turbine compartments by the steam heating of the hollow guide blades are considered. To ensure the dynamic stability of the shafting, shroud and diaphragm seals that prevent the development of the destabilizing circulatory forces of the steam flow were devised and trialed. Advanced instrumentation and software are proposed to monitor the condition of the blading and thermal stresses under transient conditions, to diagnose the vibration processes, and to archive the obtained data. Attention is paid to the normalization of the electromagnetic state of the plant in order to prevent the electrolytic erosion of the plant components. The instrumentation intended for monitoring the relevant electric parameters is described.
