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RISS 인기검색어
- 검색키워드
- 저자 : Wuyin Jin (검색결과 3 건)
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Influence of Feed Velocity on Nonlinear Dynamics of Turning Process
An Wang,Wuyin Jin 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.22 No.6
A more comprehensive orthogonal turning model is developed in order to further study the influence of feed velocity on frictional chatter. Nonlinear dynamic behavior of the cutting tool in two directions is presented by using bifurcation diagram, phase portrait, and Poincare section. It can be found that the cutting tool has a variety of dynamic behaviors at different feed velocity and cutting velocity, such as periodic motion, quasi-periodic motion, and chaotic motion. Furthermore, the vibration displacement of the cutting tool is affected by the feed velocity, especially for relatively high feed velocity which will result in the cutting tool vibration displacement increase in the cutting direction but a decrease in the feed direction. In addition, it is clear that the stick–slip phenomenon only appears in the cutting direction in our work.
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Impact of numerical choices on water conservation in the E3SM Atmosphere Model version 1 (EAMv1)
Zhang, Kai,Rasch, Philip J.,Taylor, Mark A.,Wan, Hui,Leung, Ruby,Ma, Po-Lun,Golaz, Jean-Christophe,Wolfe, Jon,Lin, Wuyin,Singh, Balwinder,Burrows, Susannah,Yoon, Jin-Ho,Wang, Hailong,Qian, Yun,Tang, Q Copernicus GmbH 2018 Geoscientific model development Vol.11 No.5
<P><p><strong>Abstract.</strong> The conservation of total water is an important numerical feature for global Earth system models. Even small conservation problems in the water budget can lead to systematic errors in century-long simulations. This study quantifies and reduces various sources of water conservation error in the atmosphere component of the Energy Exascale Earth System Model.</p> <p>Several sources of water conservation error have been identified during the development of the version 1 (V1) model. The largest errors result from the numerical coupling between the resolved dynamics and the parameterized sub-grid physics. A hybrid coupling using different methods for fluid dynamics and tracer transport provides a reduction of water conservation error by a factor of 50 at 1<span class='inline-formula'><sup>∘</sup></span> horizontal resolution as well as consistent improvements at other resolutions. The second largest error source is the use of an overly simplified relationship between the surface moisture flux and latent heat flux at the interface between the host model and the turbulence parameterization. This error can be prevented by applying the same (correct) relationship throughout the entire model. Two additional types of conservation error that result from correcting the surface moisture flux and clipping negative water concentrations can be avoided by using mass-conserving fixers. With all four error sources addressed, the water conservation error in the V1 model becomes negligible and insensitive to the horizontal resolution. The associated changes in the long-term statistics of the main atmospheric features are small.</p> <p>A sensitivity analysis is carried out to show that the magnitudes of the conservation errors in early V1 versions decrease strongly with temporal resolution but increase with horizontal resolution. The increased vertical resolution in V1 results in a very thin model layer at the Earth's surface, which amplifies the conservation error associated with the surface moisture flux correction. We note that for some of the identified error sources, the proposed fixers are remedies rather than solutions to the problems at their roots. Future improvements in time integration would be beneficial for V1.</p> </P>
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