The Experts below are selected from a list of 85155 Experts worldwide ranked by ideXlab platform
Satish C Sharma - One of the best experts on this subject based on the ideXlab platform.
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performance of hydrostatic tilted thrust pad bearings of various recess Shapes operating with non newtonian lubricant
2014Co-Authors: Saurabh K Yadav, Satish C SharmaAbstract:Abstract Hydrostatic thrust bearings are an integral part of hydroelectric power stations. These bearings are usually designed to work under parallel operation, but tilt is inevitable due to manufacturing errors, assembly errors, structural vibrations and structural deformations. Owing to the advent of latest advancements in manufacturing techniques, any Geometric Shape of recess can be easily manufactured and the designer has a greater flexibility. The Geometric Shape of recess significantly affects the performance of a bearing. Therefore, the present study is aimed to numerically analyze the influence of the tilt and recess Shape on the static and dynamic performance characteristics of the hydrostatic thrust pad bearing system having Rabinowitsch fluid model lubricant. The lubricant obeying Rabinowitsch fluid model with tilt makes the Reynolds equation highly non-linear therefore, finite element method is used to analyze. Three different types of recess Shapes of equal area A ¯ b / A ¯ o c = 4 have been analyzed to model hydrostatic thrust pad compensated by orifice compensator. The numerically simulated results indicate that the tilt angle significantly affects the dynamic and static characteristic parameters. The value of pocket pressure and fluid film reaction of a hydrostatic thrust pad bearing has been found to significantly decrease with tilt whereas the value of lubricant flow, fluid film stiffness coefficient and fluid damping coefficient increase with tilt.
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orifice compensated multirecess hydrostatic hybrid journal bearing system of various Geometric Shapes of recess operating with micropolar lubricant
2011Co-Authors: Rajasekhar E Nicodemus, Satish C SharmaAbstract:Abstract The objective of the present paper is to study analytically the performance of four-pocket orifice compensated hydrostatic/hybrid journal bearing system of various Geometric Shapes of recess operating with micropolar lubricant. The modified Reynolds equation for micropolar lubricant is solved using FEM and the Newton–Raphson method along with appropriate boundary conditions. The results suggest that the influence of micropolar effect of lubricant on bearing performance is predominantly affected by the Geometric Shape of recess and restrictor design parameter. Therefore, the bearing designer must judiciously choose an appropriate Geometric Shape of recess in order to get an overall enhanced bearing performance.
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influence of recess Shape on the performance of a capillary compensated circular thrust pad hydrostatic bearing
2002Co-Authors: Satish C Sharma, S C Jain, D K BharukaAbstract:Abstract This work describes a theoretical study concerning the static and dynamic performance of a circular thrust pad hydrostatic bearing having recesses of different Geometric Shapes. The Finite Element Method has been used to compute the performance characteristics of a circular thrust pad hydrostatic bearing with circular, rectangular, elliptical and annular recesses. The performance has been compared on the basis of the same bearing operating and the same Geometric parameters, i.e. the same ratio of bearing to pocket area ( A ) and the same value of restrictor design parameter C s2 . Further, a comparative study of the various bearing configurations has been carried out vis-a-vis different compensating devices such as capillary, orifice, and constant flow valve restrictors so as to study the combined influence of the Geometric Shape of recesses and the compensating device on bearing performance. The computed results indicate that to get an improved performance from a hydrostatic circular thrust pad bearing, a proper selection of the Geometric Shape of the recess in conjunction with the type of restrictor and the value of the restrictor design parameter C s2 is essential.
Larry J. Leamy - One of the best experts on this subject based on the ideXlab platform.
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integration and modularity of quantitative trait locus effects on Geometric Shape in the mouse mandible
2004Co-Authors: Christian Pete Klingenberg, Larry J. Leamy, James M CheverudAbstract:The mouse mandible has long served as a model system for complex morphological structures. Here we use new methodology based on Geometric morphometrics to test the hypothesis that the mandible consists of two main modules, the alveolar region and the ascending ramus, and that this modularity is reflected in the effects of quantitative trait loci (QTL). The Shape of each mandible was analyzed by the positions of 16 morphological landmarks and these data were analyzed using Procrustes analysis. Interval mapping in the F(2) generation from intercrosses of the LG/J and SM/J strains revealed 33 QTL affecting mandible Shape. The QTL effects corresponded to a variety of Shape changes, but ordination or a parametric bootstrap test of clustering did not reveal any distinct groups of QTL that would affect primarily one module or the other. The correlations of landmark positions between the two modules tended to be lower than the correlations between arbitrary subsets of landmarks, indicating that the modules were relatively independent of each other and confirming the hypothesized location of the boundary between them. While these results are in agreement with the hypothesis of modularity, they also underscore that modularity is a question of the relative degrees to which QTL contribute to different traits, rather than a question of discrete sets of QTL contributing to discrete sets of traits.
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Quantitative genetics of Geometric Shape in the mouse mandible
2001Co-Authors: Christian Peter Klingenberg, Larry J. LeamyAbstract:We combine the methods of Geometric morphometrics and multivariate quantitative genetics to study the patterns of phenotypic and genetic variation of mandible Shape in random-bred mice. The data are the positions of 11 landmarks on the mandibles of 1,241 mice from a parent-offspring breeding design. We use Procrustes superimposition to extract Shape variation and restricted maximum likelihood to estimate the additive genetic and environmental components of variance and covariance. Matrix permutation tests showed that the genetic and phenotypic as well as the genetic and environmental covariance matrices were similar, but not identical. Likewise, principal component analyses revealed correspondence in the patterns of phenotypic and genetic variation. Patterns revealed in these analyses also showed similarities to features previously found in the effects of quantitative trait loci and in the phenotypes generated in gene knockout experiments. We used the multivariate version of the breeders' equation to explore the potential for short-term response to selection on Shape. In general, the correlated response is substantial and regularly exceeds the direct response: Selection applied locally to one landmark usually produces a response in other parts of the mandible as well. Moreover, even selection for shifts of the same landmark in different directions can yield dramatically different responses. These results demonstrate the role of the geometry and anatomical structure of the mandible, which are key determinants of the patterns of the genetic and phenotypic covariance matrices, in molding the potential for adaptive evolution.
Duhwan Mun - One of the best experts on this subject based on the ideXlab platform.
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Counter-deformed design of ship structural parts using Geometric Shape deformation based on welding distortion estimation
2015Co-Authors: Sang-uk Cheon, Byung Chul Kim, Duhwan MunAbstract:We introduce a method for designing manufacturing Shapes for the structural parts of a ship that considers the weld-induced deformation. In this study, the design Shape of a bracket was counter-deformed using a purely Geometric method rather than a thermo-elastic method. The deformation quantities were estimated based on data captured in the field, and a manufacturing design Shape was obtained by counter-deforming an original design Shape using the proposed Geometric deformation method. The proposed method was implemented and tested in a shipyard.
Sharath S Girimaji - One of the best experts on this subject based on the ideXlab platform.
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characterization of velocity gradient dynamics in incompressible turbulence using local streamline geometry
2020Co-Authors: Rishita Das, Sharath S GirimajiAbstract:This study develops a comprehensive description of local streamline geometry and uses the resulting Shape features to characterize velocity gradient ( ) dynamics. The local streamline Geometric Shape parameters and scale factor (size) are extracted from by extending the linearized critical point analysis. In the present analysis, is factorized into its magnitude ( ) and normalized tensor . The Geometric Shape is shown to be determined exclusively by four parameters: second invariant, ( ); third invariant, ( ); intermediate strain rate eigenvalue, ; and vorticity component along intermediate strain rate eigenvector, . Velocity gradient magnitude, , plays a role only in determining the scale of the local streamline structure. Direct numerical simulation data of forced isotropic turbulence ( ) is used to establish streamline Shape and scale distribution, and then to characterize velocity-gradient dynamics. Conditional mean trajectories (CMTs) in – space reveal important non-local features of pressure and viscous dynamics which are not evident from the -invariants. Two distinct types of – CMTs demarcated by a separatrix are identified. The inner trajectories are dominated by inertia–pressure interactions and the viscous effects play a significant role only in the outer trajectories. Dynamical system characterization of inertial, pressure and viscous effects in the – phase space is developed. Additionally, it is shown that the residence time of – CMTs through different topologies correlate well with the corresponding population fractions. These findings not only lead to improved understanding of non-local dynamics, but also provide an important foundation for developing Lagrangian velocity-gradient models.
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characterization of velocity gradient dynamics in incompressible turbulence using local streamline geometry
2020Co-Authors: Rishita Das, Sharath S GirimajiAbstract:This study develops a comprehensive description of local streamline geometry and uses the resulting Shape features to characterize velocity gradient ($A_{ij}$) dynamics. The local streamline Geometric Shape parameters and scale-factor (size) are extracted from $A_{ij}$ by extending the linearized critical point analysis. In the present analysis, $A_{ij}$ is factorized into its magnitude ($A \equiv \sqrt{A_{ij}A_{ij}}$) and normalized tensor $b_{ij} \equiv A_{ij}/A$. The Geometric Shape is shown to be determined exclusively by four $b_{ij}$ parameters -- second invariant, $q$; third invariant, $r$; intermediate strain-rate eigenvalue, $a_2$; and, angle between vorticity and intermediate strain-rate eigenvector, $\omega_2$. Velocity gradient magnitude $A$ plays a role only in determining the scale of the local streamline structure. Direct numerical simulation data of forced isotropic turbulence ($Re_\lambda \sim 200 - 600$) is used to establish streamline Shape and scale distribution and, then to characterize velocity-gradient dynamics. Conditional mean trajectories (CMTs) in $q$-$r$ space reveal important non-local features of pressure and viscous dynamics which are not evident from the $A_{ij}$-invariants. Two distinct types of $q$-$r$ CMTs demarcated by a separatrix are identified. The inner trajectories are dominated by inertia-pressure interactions and the viscous effects play a significant role only in the outer trajectories. Dynamical system characterization of inertial, pressure and viscous effects in the $q$-$r$ phase space is developed. Additionally, it is shown that the residence time of $q$-$r$ CMTs through different topologies correlate well with the corresponding population fractions. These findings not only lead to improved understanding of non-local dynamics, but also provide an important foundation for developing Lagrangian velocity-gradient models.
Sang-uk Cheon - One of the best experts on this subject based on the ideXlab platform.
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Counter-deformed design of ship structural parts using Geometric Shape deformation based on welding distortion estimation
2015Co-Authors: Sang-uk Cheon, Byung Chul Kim, Duhwan MunAbstract:We introduce a method for designing manufacturing Shapes for the structural parts of a ship that considers the weld-induced deformation. In this study, the design Shape of a bracket was counter-deformed using a purely Geometric method rather than a thermo-elastic method. The deformation quantities were estimated based on data captured in the field, and a manufacturing design Shape was obtained by counter-deforming an original design Shape using the proposed Geometric deformation method. The proposed method was implemented and tested in a shipyard.
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Counter-Deformed Design of Ship Structural Parts Using Geometric Shape Deformation Based on Welding Distortion Estimation
2013Co-Authors: Sang-uk CheonAbstract:We introduce a method to design manufacturing Shapes of ship plate parts that considers weld-induced deformation. The design Shape of a bracket is counter-deformed by a pure Geometric method. Deformation quantities are estimated based on data captured in the field, and a manufacturing design Shape is obtained by counter-deforming an original design Shape by the proposed Geometric deformation method.