• Title/Summary/Keyword: rotational velocity

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Response of rotational parameter in the stagnation point with motile microorganism: Unsteady nanofluid

  • Mohamed A. Khadimallah;Imene Harbaoui;Sofiene Helaili;Abdelhakim Benslimane ;Humaira Sharif ;Muzamal Hussain;Muhammad Nawaz Naeem;Mohamed R. Ali;Aqib Majeed;Abdelouahed Tounsi
    • Advances in concrete construction
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    • v.15 no.4
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    • pp.241-249
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    • 2023
  • The unsteady mixed convection Casson type MHD nanofluid flow in the stagnation point with motile microorganism around a spinning sphere is investigated. Time dependent flow dynamics is considered. Similarity transformations have been employed to transfer the governing partial differential structure into ordinary differential structure. The impact of distinct parameters is examined via tables and graphs. The impact of rotational parameter (spin) on profiles of velocity profiles, temperature and concentration is revealed for unsteady mixed convection Casson type MHD nanofluid flow. It is observed that it is clear that rotational parameter has a great effect on non-dimensional primary velocity component but rotational parameter has a slight impact on non-dimensional secondary velocity component. The validity of the current investigation is authorized through comparing the existing outcomes with previous published literature.

Structrual Dynamic Analysis of a Diving Springboard to Reach Settled Height - Using Co-rotational Formulation (다이버가 일정한 높이로 도약 시 CR기법을 이용한 스프링보드의 구조 동역학적 해석)

  • Lee, Ji-Woo;Lee, Sang-Yeob;Lee, Sang-Hyeon
    • Proceeding of EDISON Challenge
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    • 2016.03a
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    • pp.217-221
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    • 2016
  • In this paper, a springboard for diving is analysed to find out how much force a diver should apply to reach specific height when the diver jumps. The springboard is presumed to Co-rotational plane cantilever beam(CR-beam), so EDISON program related to Co-rotational framework is used. The force of the person is supposed to sine function and the demanded height is fixed. Same velocity makes same height regardless of diver's weight. So, the velocity of springboard when the feet of a diver are separated from the springboard is a main factor of the analysis. The result shows that there is no association between deformation and weight and also between velocity and weight. That is, the required force to reach a optimal height is fixed whatever the diver's weight is.

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Improvement of Rotational Molding Products (회전성형 제품의 성능 개선)

  • Lee, Hyeong-Min;Kim, Hyun-Joo;Lee, Jung-Ki
    • Proceedings of the KSME Conference
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    • 2003.11a
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    • pp.1834-1839
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    • 2003
  • Temperature and velocity distributions of hot air flows in rotational molding machines with two different shapes and structures of oven and inlet were investigated by using FLUENT, a commercial computational fluid dynamics code. The shape and structure of oven and inlet in current rotational molding machine were improved. Two different sizes of mold inside each oven were considered in the analysis. Temperature and velocity distributions of hot air flows in two different rotational molding machines were compared to each other. In order to reduce cycle time and improve product quality in current rotational molding machine, the improved shape and structure of oven and inlet were proposed.

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Short-term Effects of Lumbar Rotation Mobilization on the Single-Leg Standing Balance Ability in Healthy People: A Pilot Study

  • Kim, Bo Kyung;Choi, Wan Suk;Heo, Seo Yoon
    • Journal of International Academy of Physical Therapy Research
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    • v.9 no.4
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    • pp.1676-1682
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    • 2018
  • The purpose of this study was to investigate the short-term effects of lumbar rotational mobilization under the single-leg standing (SLS) position. Fifteen healthy individuals were recruited, and randomized to agroup of trunk rotational exercise (TRE) and lumbar rotational mobilization (LRM). Trunk twist rotational exercise was performed to the TRE group, and mobilization was applied to the LRM group on the lumbar spine. Velocity of the center of pressure (VCOP) and center of pressure (COP) for each participant were measured through SLS. COPs were not significantly increased or decreased after treatment in both groups. VCOPs also did not change considerably except on the right side when the eye was closed. There was no significant difference between COPs and VCOPs in two groups. This study suggests that trunk rotation exercise and lumbar rotation mobilization would have similar effects on balance ability.

태양 주위에 있는 만기형 주계열성의 자전에 관한 연구

  • Yang, Eun-Su;Lee, Sang-Gak
    • Publications of The Korean Astronomical Society
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    • v.4 no.1
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    • pp.31-52
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    • 1989
  • The rotational properties of late-type main sequence stars in the solar neighborhood have been investigated. So rotation periods and stellar radii are determined for 104 field stars, 8 Ursa Major Group stars, and 20 Hyades cluster stars. Most of the rotation periods are derived using the Noyes et al. (1984)'s relation between chromospheric activity and rotation period. Stellar radii are calculated by the Stefan law for the nearby stars within 25 pc from the sun. Rotational velocities at equator are determined by the above rotation periods and stellar radii. Their distribution along the (B-V) color shows an upper boundary and an abrupt drop for the stars in the range of 0.4<(B-V)<0.8, as found from the apparent rotational velocity data. Furthermore, it is apparent that there is an lower boundary of rotational velocity. The inclination of rotation axis to line-of-sight is obtained by comparing the rotational velocity at equator with the apparent rotational velocity given by the analysis of the line profiles. For the field stars, it is found that the inclination has no correlation with the galactic lattitude and follows random distribution.

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A Study on Translational and Rotational Velocity Performance Indices of Six-Degree-of-Freedom parallel Mechanism (6자유도를 갖는 병렬형 기구의 병진속도와 회전속도 성능 지표에 관한 연구)

  • Kim, Chan-Soo
    • Journal of Korea Game Society
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    • v.10 no.6
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    • pp.57-65
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    • 2010
  • In this paper, mobility performance indices are proposed which may be used to estimate characteristics of output velocity space in six-degree-of-freedom parallel mechanism. In order for manipulability and condition number to not suffer from lack of the physical meaning due to dimensional inhomogeneity, output space is partitioned into translational velocity space and rotational velocity space, respectively. In each space, mobility ellipsoids corresponding to unit input space are defined and two types of mobility performance in translational velocity spaces indices are derived. Two types of mobility performance in rotational velocity spaces indices are derived.

Determination of Designing Condition for a Velocity of Inequality Rotatonal Equipment with Non-Circular Gears. (비원형기어를 이용한 부등속 회전기구의 설계 변수에 관한 연구)

  • 차철웅;최상훈
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1996.11a
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    • pp.861-866
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    • 1996
  • The Non-Circular Gears is more advantage than other machinery using link and cam in the automation equipment. We designed Non-Circular Gears for a velocity of inequalty rotational equipment according to the variation of pressure angle, radius of curvature etc., and studied about pitch curve.

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An Upper Bound Analysis for the Twisting Phenomenon of Extrusion of Elliptical Shapes from Round Billet (상계해법에 의한 원형빌렛으로부터 타원 단면을 가진제품의 압출가공의 비틀림 해석)

  • 김한봉;진인태
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 1998.03a
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    • pp.210-213
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    • 1998
  • A kinematically admissible velocity field is developed for the analysis of twisting of extruded products. The twisting of extruded product is caused by the linearly increased rotational velocity from the center on the cross-section of the workpiece at the die exit. In the analysis, the rotational velocity in angular direction is assumed by the multiplication of radial distance and angular velocity. The angular velocity is zero at the die entrance and is increased linearly by axial distance from die entrance. The increase rate of angular velocity is determined by the minimization of plastic work. The results of the analysis show that the angular velocity of the extruded product increase with the die twisting angle and the aspect ratio of product and friction condition and reduction area and show that angular velocity increases with the decreases in die length.

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An Upper Bound Analysis for the Twisting Phenomenon of Extrusion (상계해법에 의한 압출가공의 비틀림 해석)

  • Kim, Han-Bong;Jin, In-Tai
    • Transactions of Materials Processing
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    • v.7 no.4
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    • pp.340-346
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    • 1998
  • A kinematically admissible velocity field is developed for the analysis of twisting of the extruded products with elliptical shapes from round billet. The twisting of extruded product is caused by the lin-early increased rotational velocity from the center on the cross-section of the workpiece at the die exit. In the analysis the rotational velocity in angular direction is assumed by the multiplication of radial distance and angular velocity. The angular velocity is zero at the die entrance. The increase rate of angular velocity is determined by the minimization of plastic work. The results of the analysis show that the angular velocity of the extruded product in creases with the die twisting angle, the aspect ratio of product the friction condition, the reduction of area, and decreases with the die length.

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An Upper Bound Analysis for the Twisting Phenomenon of Extrusion of S shape from Round Billet (상계해법에의한 원형빌렛으로부터 S형 단며의 압출가공의 비틀림 해석)

  • 진인태
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 1997.03a
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    • pp.130-135
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    • 1997
  • A kinematically admissible velocity field is developed for the analysis of twisting of extruded products. The twisting of extruded product is caused by the linearly increased rotational velocity from the center on the cross-section of the workpiece at the die exit. In the analysis, the rotational velocity in angular direction is assumed by the multiplication of radial distance and angular velocity. The angular velocity is zero at the die entrance and is increased linearly by longitudinal distance from die entrance. The increase rate of angular velocity is determined by the minimization of plastic work. The results of the analysis show that the angular velocity of the extruded product changes with the aspect ratio of product and increases with the decreases in die length and in eccentricity of gravity center of the cross-section of workpiece at die entrance from that of the cross-section at the die exit.

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