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1
Oyang, Bryance, Yan-Fei Jiang (姜燕飞) i Omer Blaes. "Investigating lack of accretion disc eccentricity growth in a global 3D MHD simulation of a superhump system". Monthly Notices of the Royal Astronomical Society 505, nr 1 (30.04.2021): 1–17. http://dx.doi.org/10.1093/mnras/stab1212.
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ABSTRACT We present the results of a 3D global magnetohydrodynamic (MHD) simulation of an AM CVn system that was aimed at exploring eccentricity growth in the accretion disc self-consistently from a first principles treatment of the MHD turbulence. No significant eccentricity growth occurs in the simulation. In order to investigate the reasons why, we ran 2D alpha disc simulations with alpha values of 0.01, 0.1, and 0.2, and found that only the latter two exhibit significant eccentricity growth. We present an equation expressing global eccentricity evolution in terms of contributing forces and use it to analyse the simulations. As expected, we find that the dominant term contributing to the growth of eccentricity is the tidal gravity of the companion star. In the 2D simulations, the alpha viscosity directly contributes to eccentricity growth. In contrast, the overall magnetic forces in the 3D simulation damp eccentricity. We also analysed the mode-coupling mechanism of Lubow, and confirmed that the spiral wave excited by the 3:1 resonance was the dominant contributor to eccentricity growth in the 2D α = 0.1 simulations, but other waves also contribute significantly. We found that the α = 0.1 and 0.2 simulations had more relative mass at larger radii compared to the α = 0.01 and 3D MHD simulation, which also had an effective α of 0.01. This suggests that in 3D MHD simulations without sufficient poloidal magnetic flux, MRI turbulence does not saturate at a high enough α to spread the disc to large enough radii to reproduce the superhumps observed in real systems.
2
Gao, Qi Ming, Guo Qing Zhao i Hai Fei Wang. "Simulation and Analysis of Roller Eccentricity Compensation in Cold Mill". Advanced Materials Research 143-144 (październik 2010): 148–51. http://dx.doi.org/10.4028/www.scientific.net/amr.143-144.148.
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With the increase request of strip quality, the roller eccentricity has become the important factor of influencing product quality. On the practical model of Cold-rolling Mill of 300, this paper establishes eccentricity compensation control practice of Cold-rolling Mill of 300 which applies wavelet transform method. Based on mufti-resolution decomposition of roll force signal by use of wavelets, eccentricity signals are separated from disturbances and noise，and self-optimization is employed to real-time control the roller eccentricity. The results show that the method is effective.
3
Wu, Nan Xing, Tian Tian Zhan i Da Hai Liao. "The Effect of Dry Granulating Machine Spindle Eccentricity on the Granulation". Advanced Materials Research 1094 (marzec 2015): 374–78. http://dx.doi.org/10.4028/www.scientific.net/amr.1094.374.
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For the dispersity of particles in the process of ceramics dry granulating, simulating the effect of spindle eccentricity on it based on the Euler-Euler model. Simulation results show that the volume fraction of particles in the granulating chamber were 52%, 53%, 51% when the spindle eccentricity were 15mm, 25mm, 35mm. For particles distribute in the region of packing density above 0.4kg/m3 , the volume fraction in the granulating chamber were 11%, 3%, 7%. Therefore, spindle eccentricity has little effect on the whole the volume fraction of particles, but the effect on particles distribute in the region of packing density above 0.4kg/m3 is larger .Particles dispersity is best in the process of granulating when spindle eccentricity is 30mm.
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Wang, Li Jun, Xiao Kang Yan, Fei Hu Li i Zi Xin Dong. "Numerical Simulation of Magnetic Fluid Lubrication". Advanced Materials Research 154-155 (październik 2010): 1498–501. http://dx.doi.org/10.4028/www.scientific.net/amr.154-155.1498.
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This paper was concerned with theoretical analysis and the static characteristics of the journal bearing lubricated with magnetic fluid. A general Reynolds equation based on magnetic fluid model is obtained, which can be easily extended to other non-Newtonian fluids and this equation can provide theoretical basis for hydrodynamic analysis of magnetic fluid journal bearings. For the case of static loaded magnetic journal bearings, the influence of magnetic fluid effects on the lubrication performance is studied under various eccentricity ratios, magnetic intensity and concentration. The numerical results show that: with the increasing of concentration, the bearing capacity is obviously increased; the increase magnitude is larger when the eccentricity ratio is large. Under the effect of magnetic field, the bearing capacity increasing with the increasing of magnetic field intensity. When the eccentricity is small, the side leakage is highly decreased. It can be completely eliminate by appropriately designing the bearing geometry and the magnetic field which can’t be existed in normal journal bearings.
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Li, Dong, Wei Xing Song, Cai Jin Zhang, Jian Chang Liu, Shu Bin Tan, Shuai Hou, Jian Ming Li i Jun Yan Xu. "Application of Dynamic Deadband Eccentricity Filter in GM-AGC System". Materials Science Forum 789 (kwiecień 2014): 587–92. http://dx.doi.org/10.4028/www.scientific.net/msf.789.587.
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The problem of roll eccentricity has become one of important factors to affect the quality of strips as downstream industries require improvement of the strip quality. Reducing thickness control precision as little as possible is incompatible with restraining roll eccentricity perturbations on the requirement of the deadband size for the deadband drift method (DDM) with fixed deadband width. Therefore, the GM-AGC system in hot finishing mill of an aluminum plant uses the dynamic deadband eccentricity filter (DDEF) whose deadband width varies with the amplitude of the roll eccentricity signal. The operating principle of DDEF was introduced according to the characteristic of roll eccentricity signal. Based on the theory of DDEF, simulation was carried out. Comparing with DDM, the simulation result shows that DDEF can keep a balance between less lowering thickness control precision and restraining roll eccentricity perturbations on the requirement of the deadband size. Moreover, the deadband width of DDEF is capable to fit the variations in the frequency and amplitude of the synthetic roll eccentricity signal to restrain the misoperation of GM-AGC system.
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Ďurčík, Roman, Ladislav Morovič, Michal Kán i Milan Mojžiš. "NUMERICAL SIMULATION OF ECCENTRICITY CREATION IN THE PRODUCTION OF HOT ROLLED TUBES". Acta Tecnología 7, nr 4 (31.12.2021): 125–29. http://dx.doi.org/10.22306/atec.v7i4.122.
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The paper deals with the issue of eccentricity in the technological node of the piercing press, under selected conditions, which result from the possibilities of production in the conditions of ŽP a.s. These conditions were verified and adapted to the rolling process. This process consisting of individual technological nodes on the rolling mill, in which eccentricity is created on the piercing press and the following steps eliminate it in other technological nodes. For quality analysis of manufacturing tubes using numerical simulation, it is necessary to know the actual state of eccentricity creation on the rolling mill. A numerical simulation of piercing under different input conditions was used (software DEFORM-3D) and was performed for several different charge states before entering onto the piercing press. The eccentricity itself has a significant effect on the resulting geometric quality of the tubes.
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Yang, Zhe, Ding Liu i Gang Zheng. "Roll Eccentricity Signal Detection and Its Engineering Application Based on SFFT-IAA". Applied Sciences 12, nr 17 (5.09.2022): 8913. http://dx.doi.org/10.3390/app12178913.
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The roll eccentricity signal is a weak and complex periodic signal that is difficult to be identified. To improve the detection accuracy of the roll eccentricity signal and to compensate effectively, this study proposed a roll eccentricity signal detection method by combining the sparse fast Fourier transform (SFFT) and the iterative adaptive approach (IAA). The proposed method can rapidly determine the frequency range of the roll eccentricity signal by using the SFFT. Then, it divides the frequency range into several small frequency bands. In each small frequency band, the frequency, amplitude, and phase angle of each harmonic component of the roll eccentricity signal were estimated by using IAA. The simulation results show that the proposed method can find all frequency components, and the frequency estimation accuracy is higher than 99.88%. Finally, the engineering application of this method and the eccentricity compensation control were investigated. In engineering applications, the proposed method can reduce the thickness fluctuation of the finished strip by 89.2%, and the product quality is improved significantly. The simulation results and engineering experiments show that the proposed method has an excellent effect on detecting and compensating roll eccentricity signals.
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Lv, Kaikai, Kaiyun Wang, Zhihui Chen, Chengbiao Cai i Lirong Guo. "Influence of Wheel Eccentricity on Vertical Vibration of Suspended Monorail Vehicle: Experiment and Simulation". Shock and Vibration 2017 (2017): 1–10. http://dx.doi.org/10.1155/2017/1367683.
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This paper investigates the influence of wheel eccentricity on vertical vibration of suspended monorail vehicle based on experiment and simulation. Two sets of tests are conducted in the first Chinese suspended monorail, and the tested acceleration is analyzed and exhibited. A multibody dynamic model of the suspended monorail vehicle is established to simulate the vertical vibration of car body excited by wheel eccentricity. The results show that there are three factors which may cause an abnormal vibration considering the track and the vehicle system. The influence of wheel eccentricity on the car body vibration was firstly analyzed. Simulated acceleration of car body has a great accordance with test. The wheel eccentricity could excite the resonance of car body at the speed of 21 km/h, and the vertical acceleration would increase considerably. Decreasing the secondary stiffness can effectively reduce the vertical vibration caused by wheel eccentricity, especially at the resonant speed. In the secondary test, the peak of car body acceleration at speed of 20 km/h is not appearing when only renewing the wheels, and the acceleration is decreasing obviously at the domain frequency. It is further determined that the abnormal vibration is mainly caused by the wheel eccentricity.
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Elplacy, F., M. Samuel i R. Mostafa. "Modelling and simulation of hot direct extrusion process for optimal product characteristics: Single and multi-response optimization approach". Advances in Production Engineering & Management 17, nr 1 (15.03.2022): 33–44. http://dx.doi.org/10.14743/apem2022.1.419.
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The study of eccentricity minimization in cylindrical products helps to reduce the mechanical vibrations and wear of related mechanical parts such as bearings, columns and gears which positively affects in maintenance costs savings and increasing production quality reliability. The main purpose of this paper is to investigate the effect of the eccentricity between the billet material and the die parts on the quality of the final product in the direct extrusion process. The input parameters to produce a cylindrical product shape are optimized in MINITAB based on Taguchi method and ANOVA. The selected material of the billet is the aluminium alloy AA2024, and the die material is Steel H13. The inputs parameters are the temperature, the die angle, the ram speed, and the presumed eccentricity. The finite element model of the process is simulated in DFORM-3D for providing the extrusion information such as the pressure, the effective stress and strain, the final product eccentricity, and the roundness error. The study is carried out on two cases of the presumed eccentricity in addition to a case of zero eccentricity. The single and multi-response optimizations are executed to obtain the optimum parameters for the minimum product eccentricity and roundness error.
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Li, Z. H., Y. L. Chen, S. Li i D. S. Bi. "Predict Stiffness of Hydraulic Press with Movable Eccentricity Loading Considering Uncertainty by Monte Carlo Simulation". Materials Science Forum 697-698 (wrzesień 2011): 721–25. http://dx.doi.org/10.4028/www.scientific.net/msf.697-698.721.
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The stiffness analysis method considering uncertainty parameters of frame hydraulic press with movable eccentricity loading in the early design stage was proposed. The mathematical analytical stiffness of the upper beam with movable eccentricity loading was built. The adaptive Monte Carlo Method was used to calculate the interval of the stiffness with random parameters. The result shows that the stiffness appears higher when the eccentricity increasing. The approach has been tested by measuring the stiffness of a 10000kN frame hydraulic press and a 15000kN frame hydraulic press.
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Yuan, Ju Long, W. T. Liu, Zhi Wei Wang, Dong Hui Wen i Zhao Zhong Zhou. "Research and Simulation on the Wear Uniformity of Lapping Plate". Key Engineering Materials 364-366 (grudzień 2007): 466–69. http://dx.doi.org/10.4028/www.scientific.net/kem.364-366.466.
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Lapping plate wear is of great influence on shape precision of workpiece. Investigation on the wear uniformity of uncertain eccentricity plane lapping was carried out in this research. The relative velocity function of the plate to the workpiece is obtained through kinematic analyses in the mode of uncertain eccentricity plane lapping, and material removal rate (MRR) function and wear uniformity function were deduced based on Preston equation. Effects of the ratio and eccentricities on the wear uniformity are discussed in detail through MATLAB simulation. Theoretical analysis and simulation results show that the ratio k1 of workpiece revolution speed to lapping plate is the key to decide whether the lapping plate is lapped uniformly. Theoretically, when k1<0, the greater |k1| is, the better the lapped uniformly of lapping plate can be. The ratio k2 of workpiece rotation speed to lapping plate has great influence on the lapped uniformly when k1 approximate 1, and k2 has little influence on the lapped uniformly when k1<0 or k1>1, Besides, a bit bigger eccentricity e1 is propitious to the lapping uniformly of the lapping plate, and bigger eccentricity e2 are also helpful to lapping uniformly of the lapping plate. And the conclusion could be extended to single-side plane lapping and double-side plane lapping process.
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Zeng, Yun, Li Xiang Zhang, Jing Qian i Cheng Li Zhang. "Shafting Vibration Simulation for Hydro Turbine Generating Sets". Applied Mechanics and Materials 444-445 (październik 2013): 1171–76. http://dx.doi.org/10.4028/www.scientific.net/amm.444-445.1171.
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Based on the transient model of hydro turbine generating sets (HTGS), the integrated simulation system of HGTS is built to study shafting stability. Given different bearing stiffness, equivalent damping coefficient and mass eccentricity, the change characteristics of shafting vibration at rated angular speed in steady and maximum angular speed in transient are simulated, and which are applied to study inferences shafting parameters and angular speed on shafting vibration. Simulation results show that the relationship between shafting vibration amplitude and angular speed is linear. however, the vibration amplitude increment produced by angular speed error will be amplified while the shafting stiffness is weaker, mass eccentricity of the runner and rotor is larger.
13
Zhang, Jie, Zheng Liang i Chuanjun Han. "Numerical Simulation of Pipeline Deformation Caused by Rockfall Impact". Scientific World Journal 2014 (2014): 1–10. http://dx.doi.org/10.1155/2014/161898.
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Rockfall impact is one of the fatal hazards in pipeline transportation of oil and gas. The deformation of oil and gas pipeline caused by rockfall impact was investigated using the finite element method in this paper. Pipeline deformations under radial impact, longitudinal inclined impact, transverse inclined impact, and lateral eccentric impact of spherical and cube rockfalls were discussed, respectively. The effects of impact angle and eccentricity on the plastic strain of pipeline were analyzed. The results show that the crater depth on pipeline caused by spherical rockfall impact is deeper than by cube rockfall impact with the same volume. In the inclined impact condition, the maximum plastic strain of crater caused by spherical rockfall impact appears when incidence angleαis45°. The pipeline is prone to rupture under the cube rockfall impact whenαis small. The plastic strain distribution of impact crater is more uneven with the increasing of impact angle. In the eccentric impact condition, plastic strain zone of pipeline decreases with the increasing of eccentricityk.
14
Shimizu, Sota, i Joel W. Burdick. "Eccentricity Compensator for Wide-Angle Fovea Vision Sensor". Journal of Robotics and Mechatronics 21, nr 1 (20.02.2009): 121–27. http://dx.doi.org/10.20965/jrm.2009.p0121.
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This paper aims at the acquisition of a robust feature for rotation, scale, and translation-invariant image matching of space-variant images from a fovea sensor. The proposed model eccentricity compensator corrects deformation in log-polar images when the fovea sensor is not centered on the target image, that is, when eccentricity exists. An image simulator in a discrete space implements this model through its geometrical formulation. This paper also proposes Unreliable Feature Omission (UFO) using the Discrete Wavelet Transform. UFO reduces local high frequency noise appearing in the space-variant image when the eccentricity changes. It discards coefficients when they are regarded as unreliable, based on digitized errors in the input image from the fovea sensor. The first simulation estimates the compensator by comparing it with other polar images. This result shows the compensator performs well, and its root mean square error (RMSE) changes only by up to 2.54% on the condition that the eccentricity is within 34.08°. The second simulation shows UFO performs well for the log-polar image remapped by the eccentricity compensator when white Gaussian noise (WGN) is added. The result from the Daubechies (7, 9) biorthogonal wavelet shows UFO reduces the RMSE by up to 0.40 %, even if the WGN is not added, when the eccentricity is within 34.08°. This paper is the full translation from the transactions of JSME Vol.73, No.733.
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Shevchenko, Aleksandr Fedorovich, i Dmitriy M. Toporkov. "Additional Torque in Multipole Permanent Magnet Machines Caused by Eccentricity". Applied Mechanics and Materials 792 (wrzesień 2015): 78–82. http://dx.doi.org/10.4028/www.scientific.net/amm.792.78.
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The additional torque caused by the static eccentricity in multipole permanent magnet machines is investigated in the paper. The equation governing the dependence of the additional torque on number of poles and the amount of eccentricity qualitatively is developed. Analytical conclusions are verified by the results of numerical simulation.
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Zhou, Qing Xiao, Chao Yang Wang, Zhi Bing Fu i Yong Jian Tang. "Numerical Simulation of Film Thickness Uniformity Deposited by Planar Circular Magnetron Sputtering System". Advanced Materials Research 887-888 (luty 2014): 743–48. http://dx.doi.org/10.4028/www.scientific.net/amr.887-888.743.
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There exist angular offset and eccentricity between target and substrate in most practical multi-target magnetron sputtering systems, which should be seriously considered when we calculate the film distribution. This simulation results suggested that excellent thickness uniformity can be obtained when increased the substrate-target distance, angular offset, and eccentricity, but decreased the film thickness simultaneously. However, superior uniformity films without reducing the thickness remarkably can also obtained when the geometry configuration are proper configured.
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Deng, Qian Fa, Ju Long Yuan, Dong Hui Wen, Feng Chen i Li Tao. "Simulation and Analysis for Application of Truing Ring in Certain Eccentricity Plane Lapping System". Key Engineering Materials 407-408 (luty 2009): 482–85. http://dx.doi.org/10.4028/www.scientific.net/kem.407-408.482.
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In plane lapping, workpiece material removal and lapping wheel wear has been influenced each other and should be evenly distributed. Only required a flat lapping wheel, it could be obtained with flat workpieces and small thickness deviations. Therefore, the choice of the truing operation has an important effect on the quality of the lapping wheel and on the flatness of product. This is a way that using truing ring to true lapping wheel in certain eccentricity plane lapping system to acquire the flatness. The kinematics of certain eccentricity plane lapping for uniformity of processing is analyzed in this paper firstly. Then different sizes and locations of truing ring that influences truing on the flatness of lapping wheel has evaluated and simulated. Lastly, a suitable truing operation of certain eccentricity plane lapping is proposed.
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Zhang, Hui Wu, Peng Wang i Hai Bo Chen. "Effect of Bolt Slippage and Joint Eccentricity on the Response of Lattice Structure with Non-Uniform Settlement". Applied Mechanics and Materials 483 (grudzień 2013): 289–96. http://dx.doi.org/10.4028/www.scientific.net/amm.483.289.
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Lattice transimission towers are commonly made of angles bolted together directly or through gussets. And angle members are usually subjected to high axial force with eccentricity. Conventional structural analysis softwares solve such problems with the assumption of regarding the bolted connection as a rigid joint connection and ignored the effect of joint eccentricity. Thus the calculated internal forces of the structure members are bigger than those of real measurements, and the calculated structure deformation are smaller than the experimental ones under the same load. The main reasons for the discrepancy between the experimental results and the analytical solutions are bolt slippage and joint eccentricity. In this paper, the displacement-load curves of the bolted connections are introduced into the finite element simulation, revealing the effect of bolt slippage on the static response of lattice structure. The simulation results show that the bolt slippage causes the redistribution of the member internal forces of the lattice structure and increases the displacement of the lattice structure. The proposed algorithm and simulation results would provide good reference for further engineering applications.
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Li, Peiai, Baoyu Wang i Jiapeng Wang. "Numerical Simulation and Experimental Study on Rotary Cold Extrusion Forming of Screw Rod". Journal of Physics: Conference Series 2101, nr 1 (1.11.2021): 012017. http://dx.doi.org/10.1088/1742-6596/2101/1/012017.
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Abstract The rotary cold extrusion forming process is a plastic forming process with very low material loss, especially in the production of hollow screw rods with equal wall thickness. In this work, the rotary cold extrusion forming process of a hollow T2 copper screw rod with a wall thickness of 4 mm and solid T2 copper screw rod was verified by experimental method. The finite element simulation software Deform-3D was also used to simulate the rotary cold extrusion forming process of the screw rod. The effects of the die with different heights of the working belt and the different wall thickness of the billet on the eccentricity, extrusion force, and forming torque in the forming process of the screw rod were studied. The results show that it is feasible to process hollow and solid T2 copper screw rods with equal wall thickness by rotary cold extrusion. With the increase of die working belt height, the eccentricity of the screw rod becomes smaller and closer to the ideal eccentricity. With the increase of the wall thickness of the billet, the amplitude fluctuation range of the eccentricity of the screw rod gradually decreases. The higher the height of the die working belt, the greater the extrusion force and torque required in the extrusion process, and the more intense the change of torque. These results also provide theoretical guidance for the production practice and lightweight transformation of the screw pump rotor.
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Hu, Yongzheng, Jun Chen, Xiaodong Shen i Jiantao Dang. "Nozzle Thrust Eccentricity Calculation Based on FLUENT Software". Journal of Physics: Conference Series 2489, nr 1 (1.05.2023): 012031. http://dx.doi.org/10.1088/1742-6596/2489/1/012031.
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Abstract Thrust eccentricity refers to the phenomenon that the thrust vector deviates from the axis of symmetry. This phenomenon will produce lateral force and torque around the aircraft, which affects the normal flight of the aircraft, increases the required control torque, and reduces the density of uncontrolled rockets. There are three sources of thrust eccentricity: mass eccentricity, geometric eccentricity, and aerodynamic eccentricity. The aerodynamic eccentricity is caused by the asymmetrical flow of combustion gas in the nozzle. This paper uses FLUENT software to carry out a numerical simulation of a cone-shaped nozzle. By changing different factors such as the structure of the inner surface of the nozzle and the convergence radius, the influence law of the inner surface structure of different nozzles on the lateral force of the pneumatic eccentricity of the nozzle is explored. The following conclusions were drawn: With the expansion of the expansion half-angle, the second zero point moves toward the nozzle outlet. The relative radius of curvature has little effect on the main thrust of the nozzle but has a certain influence on the eccentricity of its thrust, and as the relative radius of curvature increases, the first and second zeros move toward the throat.
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Zhang, Feng Ling, Rui Han, Yin Peng i Lei Wang. "Vision Based Eccentricity Measurement of Auto-Hub and its Simulation". Advanced Materials Research 503-504 (kwiecień 2012): 1420–23. http://dx.doi.org/10.4028/www.scientific.net/amr.503-504.1420.
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A machine vision based measurement system of auto-hub’s eccentricity between the center circle and the pitch circle of bolt holes is proposed in this article. Pictures of all bolt holes are shot when the auto-hub is rotating. The eccentricity can be calculated by tiling these pictures to a global image. There are some error factors in the system such as run-out of rotation center, inclined platform, rotation angle error, tilted auto-hub’s surface, roundness of the center hole and angle between bolt holes uneven. Mathematical models of these error factors are studied. By stimulating all these error factors, run-out of rotation center has the greatest impact and some key parameters are given in mechanical system design.
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Návrat, Tomáš, David Halabuk, Miloš Vlk i Petr Vosynek. "Eccentricity Effect in the Hole-Drilling Residual Stress Measurement". Defect and Diffusion Forum 382 (styczeń 2018): 208–12. http://dx.doi.org/10.4028/www.scientific.net/ddf.382.208.
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The paper focuses on the analysis of the eccentricity effect in the measurement of the hole-drilling residual stress. Relaxed strains were evaluated by computational simulation of the hole-drilling experiment using the finite element method. Errors induced by eccentricity were estimated for elastic and elastic-plastic states in area around the drilled hole due to the stress concentration. The invariance of the stress change with depth was assumed. The correction of eccentricity and plasticity effects in evaluation of residual stresses was realized within the EVAL 7 software (SINT Technology). The analysis shows that in elastic state the eccentricity and angular position of the drilled hole have a significant effect on relative residual stress errors. Correction according to the HDM method is very effective in this case. If the relative error of 5 % is allowed, which is in engineering practice acceptable, eccentricity of ±0.05 mm could be accepted without correction. When the combination of eccentricity and plasticity occurs, the correction of plasticity is more important in method 13-EXT-UN.
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Koppelman, Helmer H., Roy O. Y. Bos i Amina Helmi. "The messy merger of a large satellite and a Milky Way-like galaxy". Astronomy & Astrophysics 642 (październik 2020): L18. http://dx.doi.org/10.1051/0004-6361/202038652.
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Aims. About 10 billion years ago the Milky Way merged with a massive satellite, Gaia-Enceladus. To gain insight into the properties of its debris we analyse in detail a suite of simulations that includes an experiment that produces a good match to the kinematics of nearby halo stars inferred from Gaia data. Methods. We compare the kinematic distributions of stellar particles in the simulations and study the distribution of debris in orbital angular momentum, eccentricity, and energy, and its relation to the mass loss history of the simulated satellite. Results. We confirm that Gaia-Enceladus probably fell in on a retrograde, 30° inclination orbit. We find that while 75% of the debris in our preferred simulation has high eccentricity (> 0.8), roughly 9% has eccentricity lower than 0.6. Star particles lost early have large retrograde motions, and a subset of these have low eccentricity. Such stars would be expected to have lower metallicities as they stem from the outskirts of the satellite, and hence naively they could be confused with debris associated with a separate system. These considerations seem to apply to some of the stars from the postulated Sequoia galaxy. Conclusions. When a massive disc galaxy undergoes a merger event, it leaves behind debris with a complex phase-space structure, a wide range of orbital properties, and a range of chemical abundances. Observationally, this results in substructures with very different properties, which can be misinterpreted as implying independent progeny. Detailed chemical abundances of large samples of stars and tailored hydrodynamical simulations are critical to resolving such conundrums.
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Karami, Mahdi, Norman Mariun, Kadir Ab, Radzi Mohd i Norhisam Misron. "Analysis of rotor asymmetry fault in three-phase line start permanent magnet synchronous motor". Facta universitatis - series: Electronics and Energetics 34, nr 4 (2021): 483–98. http://dx.doi.org/10.2298/fuee2104483k.
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This article proposed a detection scheme for three-phase Line start permanent magnet synchronous motor (LSPMSM) under different levels of static eccentricity fault. Finite element method is used to simulate the healthy and faulty LSPMSM with different percentages of static eccentricity. An accurate laboratory test experiment is performed to evaluate the proposed index. Effects of loading condition on LSPMSM are also investigated. The fault related signatures in the stator current are identified and an effective index for LSPMSM is proposed. The simulation and experimental results indicate that the low frequency components are an effective index for detection of the static eccentricity in LSPMSM.
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Yuan, Yong Wen, Yan Jun Cheng, Jin Xin Zhu i Liu Yi Li. "Three-Dimensional Simulation of the Influences of Operational Parameters on Stability of Formation-Cement Sheath-Casing Combination". Materials Science Forum 980 (marzec 2020): 525–46. http://dx.doi.org/10.4028/www.scientific.net/msf.980.525.
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At present, most of the studies of the stability of the formation-cement sheath-casing combination have been mainly based on the plane, and the three-dimensional model established is only one example. There is no systematic study of the influence of physical parameters and process parameters on the stability of the combined body under the three-dimensional model and the action of triaxial crustal stress. Through the establishment of three-dimensional formation-cement sheath-casing linear elastic combination model, we can study the influence of operational parameters (cement sheath pressure, casing cross section pressure, inner casing pressure, ellipticity of borehole, centrality of casing, thickness of cement sheath) by the two interfaces’ Von Mises stress and the total displacement of the combination body. It is pointed out that the pressure of cement sheath, and casing cross section pressure have no effect on the stability of formation, cement sheath and casing; The higher the ellipticity of the borehole, the eccentricity of the casing (position 1, 2) and the thickness of the cement sheath, the higher the stability of the second interface of the cementing; The higher the inner casing pressure and the eccentricity of the casing(position 3), the lower the stability of the second interface of the cementing; The higher the eccentricity of the casing (position 2,3) and the thickness of the cement sheath, the higher the stability of the first interface of the cementing; The higher the inner casing pressure, the eccentricity of the casing (position 1) and the ellipticity of the borehole, the lower the stability of the first interface of the cementing; The higher the eccentricity of the casing (position 2,3) and thickness of the cement sheath, the higher the stability of the casing; The higher the inner casing pressure, the ellipticity of the borehole and the eccentricity of the casing(position 1), the lower the stability of the casing. Through this study, according to the formation stress, the formation physical parameters (elastic modulus, Poisson's ratio, density), optimize the operational parameters, ensure the long-term integrity of the combination.
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Han, Jian Yong, i Guo Jing Chen. "Numerical Simulation Analysis of Centrifugal Pump Floating Ring Seal". Advanced Materials Research 317-319 (sierpień 2011): 2148–51. http://dx.doi.org/10.4028/www.scientific.net/amr.317-319.2148.
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According to the studying on the force analysis of floating ring of centrifugal pump, the paper think that floating ring stress will change with the change of centrifugal pump’ s condition. Using fluent software, the floating ring seal was simulated and analyzed. Results show that the liquid force acted on the floating ring is nonuniform and asymmetrical as wedging effect, and that section maximum pressure is not lies in the smallest clearance place, but in the wedge area where liquid flows to the minimum clearance, because the effect of Leak resistance is better in high pressure than low pressure. The leakage decreases and liquid resistance increases with the increases of RPM. The leakage increases with the increases of differential pressure in sealing ring sides and eccentricity. Pressure distribution within the seal clearance is not uniform with the increases of eccentricity.
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Tian, Kun, Tao Zhang, Yibo Ai i Weidong Zhang. "Induction Motors Dynamic Eccentricity Fault Diagnosis Based on the Combined Use of WPD and EMD-Simulation Study". Applied Sciences 8, nr 10 (20.09.2018): 1709. http://dx.doi.org/10.3390/app8101709.
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The frequency-domain analysis using the fast Fourier transform (FFT) for diagnosis of eccentricity fault has been widely used in squirrel-cage induction motor (IM). However, with the restriction of sampling frequency and time acquisition, FFT analysis could not provide ideal results under low levels of dynamic eccentricity (DE). In this paper, a combined use of the wavelet packet decomposition (WPD) and empirical mode decomposition (EMD) method is presented to diagnose the IM fault under low degrees of purely DE. The proposed method is based on the decomposition of apparent power signal and extracts the characteristic component. The fault severity factor (FSF) has been defined to evaluate the eccentricity severity. Simulation results using the finite element method (FEM) are tested to verify the effectiveness of the presented method under different load conditions.
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Ye, Qing Ying, Shui Yuan Chen, Zhi Ming Lin, Hong Ying Xiong, Xiu Wan Yang, Ling Fang Li, Ling Gao i Zhi Gao Huang. "Study of Magnetic Properties for Fe Nanoring with Different Degree of Eccentricity". Materials Science Forum 817 (kwiecień 2015): 784–90. http://dx.doi.org/10.4028/www.scientific.net/msf.817.784.
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In this paper, Fe nanoring model of different degree of eccentricity has been made. Based on the FFTM method and MC simulation method, the magnetic properties of the Fe nanoring, such as hysteresis loops, spin configuration, have been studied. The simulated results indicate that there are typical hysteresis loops and spin-configurations, such as onion-type state and vortex-type state in the system of symmetric Fe nanoring. The hysteresis loops of the eccentric Fe nanoring are similar to symmetric system when the degree of eccentricity is small, but as the degree of eccentricity increased, the magnetization behavior become different. Remanence is almost linearly related to the degree of eccentricity in the system of eccentric Fe nanoring, which can be explained by analyzing the change of spin-configurations in the eccentric Fe nanoring.
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Chen, Bing, i Yu Guang Fan. "3D Modeling and Open-Close Motion Simulation of the Triple Eccentric Butterfly Valve". Advanced Materials Research 215 (marzec 2011): 191–94. http://dx.doi.org/10.4028/www.scientific.net/amr.215.191.
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It was achieved with the benefit of excellent molding function of CAD/CAM, to solve the designing problems of rotation center of triple eccentric butterfly valve and to improve the seal performance. The Solid Edge software is applied to analyze the process of 3D modeling and motion simulation with details, as well as check both static and dynamic interference. In this way, the reasonable eccentric angle α, cone-apex angle 2β, radial eccentricity e and axial eccentricity C of valve board are acquired. It is effective to shorten the design period of triple eccentric butterfly valve, also improve the design efficiency and quality.
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Gu, X., i P. Velex. "On the dynamic simulation of eccentricity errors in planetary gears". Mechanism and Machine Theory 61 (marzec 2013): 14–29. http://dx.doi.org/10.1016/j.mechmachtheory.2012.10.003.
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Joksimovi, G. M. "Dynamic simulation of cage induction machine with air gap eccentricity". IEE Proceedings - Electric Power Applications 152, nr 4 (2005): 803. http://dx.doi.org/10.1049/ip-epa:20041229.
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Li, Hongqiang, i Ruihe Wang. "Research on a Measurement Method for Downhole Drill String Eccentricity Based on a Multi-Sensor Layout". Sensors 21, nr 4 (10.02.2021): 1258. http://dx.doi.org/10.3390/s21041258.
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The drill string used in drilling is in a complex motion state downhole for several kilometers. The operating attitude and eccentricity of the downhole drill string play important roles in avoiding downhole risks and correcting the output of the imaging measurement sensor while drilling (IMWD). This paper proposes a method for measuring eccentricity while drilling using two sets of caliper sensors coupled with a fiber-optic gyroscope for continuous attitude measurement, which is used to solve the problem of the quantitative measurement of complex eccentricity that changes in real-time downhole. According to the measurement and calculation methods involved in this article, we performed simulations of the attitude of the drill string near where the IMWD tool is located in the wellbore under a variety of complex downhole conditions, such as centering, eccentricity, tilt, buckling, rotation, revolution, etc. The simulation and field test results prove that the distance between the imaging while drilling sensor and the borehole wall is greatly affected by the downhole attitude and revolution. The multi-sensor layout measurement scheme and the data processing based on the above-mentioned measurement involved can push the drill collar movement and eccentricity matrix specifically studied downhole from only qualitative estimation to real-time measurement and quantitative calculation. The above measurement and data processing methods can accurately measure and identify the local operating posture of the drill string where the IMWD sensor is located, and quantitatively give the eccentric distance matrix from the measuring point to the borehole wall required for environmental correction of the IMWD sensor.
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Geller, Aaron M., Jarrod R. Hurley i Robert D. Mathieu. "The progeny of stellar dynamics and stellar evolution within an N-body model of NGC 188". Proceedings of the International Astronomical Union 5, S266 (sierpień 2009): 258–63. http://dx.doi.org/10.1017/s1743921309991128.
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AbstractWe present a direct N-body simulation modeling the evolution of the old (7 Gyr) open cluster NGC 188. This is the first N-body open cluster simulation whose initial binary population is directly defined by observations of a specific open cluster: M35 (150 Myr). We compare the simulated color–magnitude diagram at 7 Gyr to that of NGC 188, and discuss the blue stragglers produced in the simulation. We compare the solar-type main-sequence binary period and eccentricity distributions of the simulation to detailed observations of similar binaries in NGC 188. These results demonstrate the importance of detailed observations in guiding N-body open cluster simulations. Finally, we discuss the implications of a few discrepancies between the NGC 188 model and observations and suggest a few methods for bringing N-body open cluster simulations into better agreement with observations.
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Усманова, E. Usmanova, Короткий, Viktor Korotkiy, Хмарова i Lyudmila Khmarova. "Computer Simulation of Kinematic Surfaces". Geometry & Graphics 3, nr 4 (17.12.2015): 19–26. http://dx.doi.org/10.12737/17347.
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A geometric surface model is formed taking into account
given functional, structural, technological, economic, aesthetic
requirements. These requirements are formulated in geometric
terms and are expressed in terms of the surface parameters. The
surface is modeled either Kinematics manner, or by way of a twodimensional
interpolation. In accordance with in accordance with
the kinematic method, the surface is formed as a continuous oneparameter
many curves that form simulated in the surface. In accordance
with the interpolation method, the surface consists of a
set of elementary two-dimensional fragments. The article considered
cinema optical method based on the use of curves of the second
order of change-nests of the eccentricity as the main shaping element.
To control the shape of the design surfaces are used for guide
ruled surfaces (cilindroidy and conoid). Computer program is
compiled, which determines the eccentricity of the forming curves
of the second order depending on the boundary conditions. The
program allows you to plot curve of the second order, given an
arbitrary set of five coplanar points and tangents. When modeling
the surface of the passing through a closed circuit, is used the mapping
of this contour in four-dimensional space. Such mapping gives
more possibilities for control surface shape. It is shown that the
kinematics method computer simulation of the surface has technological
advantages properties instead of interpolation method.
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Teyssandier, Jean, i Dong Lai. "Pulsed disc accretion driven by Hot jupiters". Monthly Notices of the Royal Astronomical Society 495, nr 4 (23.05.2020): 3920–28. http://dx.doi.org/10.1093/mnras/staa1363.
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ABSTRACT We present 2D hydrodynamical simulations of hot Jupiters orbiting near the inner edge of protoplanetary discs. We systemically explore how the accretion rate at the inner disc edge is regulated by a giant planet of different mass, orbital separation, and eccentricity. We find that a massive (with planet-to-star mass ratio ≳0.003) eccentric (ep ≳ 0.1) planet drives a pulsed accretion at the inner edge of the disc, modulated at one or two times the planet’s orbital frequency. The amplitude of accretion variability generally increases with the planet mass and eccentricity, although some non-monotonic dependences are also possible. Applying our simulation results to the T Tauri system CI Tau, where a young hot Jupiter candidate has been detected, we show that the observed luminosity variability in this system can be explained by pulsed accretion driven by an eccentric giant planet.
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Novák, Pavol, Milan Sága, Milan Vaško, Peter Kopas i Marián Handrik. "Numerical Simulation of Electron Beam Welding of Aluminum Alloys". MATEC Web of Conferences 357 (2022): 02008. http://dx.doi.org/10.1051/matecconf/202235702008.
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The aim of this paper is to investigate the influence of technological parameters of the welding process on the level of the residual stresses, distortions, and phase proportions. The preheating temperature and the eccentricity of the weld path are taken into account. The Visual Weld tool from ESI Group was used for simulation.
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Birajdar, Ravindra S., Appasaheb A. Keste i Shravan H. Gawande. "Critical Hydraulic Eccentricity Estimation in Vertical Turbine Pump Impeller to Control Vibration". International Journal of Rotating Machinery 2021 (31.07.2021): 1–11. http://dx.doi.org/10.1155/2021/6643282.
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In many applications, pumps are tested against standard specifications to define the maximum allowable vibration amplitude limits of a pump. It is essential to identify the causes of vibration and methods to attenuate the same to ensure the safe and satisfactory operation of a pump. Causes of vibration can be classified mainly into mechanical and hydraulic nature. Respective unbalance masses are the two major factors which cause dynamic effects and excitation forces leading to undesirable vibrations. In this paper, the procedure of vibration magnitude measurement of a vertical turbine pump at site and the process of dynamic balancing to measure mechanical unbalance of an impeller are explained. After that, the impact of hydraulic eccentricity on the vibration displacement of a vertical turbine pump has been explained using numerical simulation procedure based on “One-way Fluid Structure Interaction (FSI).” The experimental results from a pump at site are used to compare the numerical results. After the solver validation, the one-way FSI approach is used to find the critical hydraulic eccentricity magnitude of a vertical turbine pump impeller to limit the vibration magnitudes on motor component to less than 100 μm. From the numerical simulations, it is deduced that the critical hydraulic eccentricity should be limited to 400 μm in X and Y direction. The process can be used as a guideline procedure for limiting the hydraulic unbalance in vertical turbine pumps by limiting the hydraulic eccentricity.
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Wang, Zhan, Wenzhi He, Siyuan Du i Zhe Yuan. "Study on the Unbalanced Fault Dynamic Characteristics of Eccentric Motorized Spindle considering the Effect of Magnetic Pull". Shock and Vibration 2021 (24.04.2021): 1–12. http://dx.doi.org/10.1155/2021/5536853.
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Unbalanced fault is the most common fault of high-speed motorized spindle, which is the main factor affecting the machining accuracy of high-speed spindle. Due to the unbalanced magnetic pull produced by the air gap eccentricity of the stator and rotor, the unbalanced vibration of the motorized spindle will be further aggravated. In order to explore the dynamic behavior and motion law of the unbalanced fault motorized spindle under the eccentric state, a dynamic model of the unbalanced fault of the high-speed motorized spindle considering the unbalanced magnetic pull was established. Taking the eccentric motorized spindle customized by the research group as the research object, the dynamic model is established, simulated, and analyzed, and the response change law of motorized spindle under the effect of different speed, unbalance, and air gap is obtained. The simulation results show that the unbalanced magnetic pull caused by static eccentricity will increase the unbalanced vibration of motorized spindle, and the unbalanced vibration will also increase with the increase of static eccentricity. The vibration caused by unbalanced magnetic pull does not increase with the increase of rotating speed. In frequency-domain analysis, when there is unbalanced magnetic pull, the peak appears at 0 Hz, and the amplitude of fundamental frequency vibration will increase with the increase of eccentricity. The experimental results show that the greater the eccentricity is, the greater the unbalance vibration of the motorized spindle is. The experimental results are consistent with the simulation results, which further verify the accuracy of the model. The research results lay a theoretical basis for fault analysis and diagnosis of coupling fault motorized spindle.
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Shimizu, Sota, i Joel W. Burdick. "Eccentricity Estimator for Wide-Angle Fovea Vision Sensor". Journal of Robotics and Mechatronics 21, nr 1 (20.02.2009): 128–34. http://dx.doi.org/10.20965/jrm.2009.p0128.
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This paper proposes a method for estimating the eccentricity that corresponds to the incident angle to a fovea sensor. The proposed method uses the Fourier-Mellin Invariant descriptor to estimate rotation, scale, and translation, by taking both geometrical distortion and non-uniform resolution of a space-variant image from the fovea sensor into account. The following 2 points are focused on in this paper. One is to use multi-resolution images by Discrete Wavelet Transform to properly reduce noise caused by foveation. Another is to use a variable window function (although the window function is generally used for reducing DFT leakage caused by both ends of a signal) to change the effective field of view (FOV) so as not to sacrifice high accuracy. The simulation compares the root mean square (RMS) of the foveation noise between uniform and non-uniform resolutions when a resolution level and a FOV level are changed, respectively. The result shows the proposed method is suitable for the wide-angle space-variant image from the fovea sensor, and, moreover, it does not sacrifice the high accuracy in the central FOV. Another simulation is done to determine a reliable resolution level. This paper is the full translation from the transactions of JSME Vol.74, No.744.
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Yang, Kexin, Gang Zheng i Zhe Yang. "Roll Eccentricity Detection and Application Based on SFT and Regional DFT". Sensors 23, nr 16 (14.08.2023): 7157. http://dx.doi.org/10.3390/s23167157.
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Roll eccentricity disturbance is a high-frequency periodic change signal caused by the irregular shape of the roll and roll bearing, which is difficult to identify and affects the periodic deviation of the exit thickness of the strip. To achieve rapid identification of the source and a mathematical model of roll eccentricity signals, a sparse Fourier transform (SFT) and regional DFT method for roll eccentricity signal recognition and detection was proposed. This method utilizes SFT to calculate the signal FFT more quickly based on the sparsity of the signal frequency domain. Under the premise of knowing the roll diameter, the signal frequency spectrum is identified online, the amplitude and phase are identified through regional DFT, and the eccentricity disturbance is compensated on site. The simulation results show that this method can accurately identify the source of roll disturbance, quickly update and replace the problematic rolls, and improve the online recognition efficiency by more than 3000 times. This method has good results in online detection and recognition of roll eccentricity signals, greatly improving engineering application efficiency, and ultimately achieving the goal of improving the accuracy of strip outlet thickness.
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Gong, Wan Ting, Rong Yang i Zong Min Liang. "Effects of Residual Stress on Bearing Capacity of Cold-Formed Thin-Walled Steel Members with “л” Section under Axial Compressive Force". Advanced Materials Research 243-249 (maj 2011): 1195–98. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.1195.
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In order to enhance the pertinence of agriculture building design, the experiment and numerical simulation on cold-formed thin-walled steel members with “л” section under axial compressive force were conducted to investigate the effects of residual stress on bearing capacity of them. For the members, there are inevitably initial defects, such as initial bending, initial eccentricity and residual stress due to the manufacturing error. In the numerical simulation, initial bending and initial eccentricity of the members were considered. The results show that the residual stress affects instability forms of the members. And as the member slenderness ratio increases from 69 to 200, the bearing capacity of member with residual stress decreases from 12.8% to 84.9% of that without residual stress.
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Joksimovic, G. M., M. D. Durovic, J. Penman i N. Arthur. "Dynamic simulation of dynamic eccentricity in induction machines-winding function approach". IEEE Transactions on Energy Conversion 15, nr 2 (czerwiec 2000): 143–48. http://dx.doi.org/10.1109/60.866991.
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Chen, Jian Feng, Xin Jin, Zhi Jing Zhang i Ting Yu Zhang. "Simulation study on the eccentricity of floater in liquid floated gyroscope". International Journal of Computer Applications in Technology 53, nr 2 (2016): 121. http://dx.doi.org/10.1504/ijcat.2016.074449.
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Eltaly, Boshra, Amen Saka i Kamel Kandil. "FE Simulation of Transmission Tower". Advances in Civil Engineering 2014 (2014): 1–13. http://dx.doi.org/10.1155/2014/258148.
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The vital components of the transmission line are the electrical transmission towers. They are commonly used to support the phase conductors and shield wires of a transmission line. Also the accurate prediction of tower failure is very important for the reliability and safety of the transmission system. The current research describes nonlinear FE models of predicting the transmission tower failure. In the current FE simulations, the eccentricity and the joint effect of the tower were considered. The current models have been calibrated with results from previous full-scale tower tests and numerical models with good accuracy in terms of both the failure load and the failure mode.
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Song, Wenzhang, Junbin Huang, Hongcan Gu, Bo Tang, Xuan Zhou, Yandong Pang, Sitong Chen i Miao Zhu. "Organic axial stretching DFB fiber laser hydrophones: Theoretical and experimental study of eccentricity". AIP Advances 12, nr 5 (1.05.2022): 055026. http://dx.doi.org/10.1063/5.0084828.
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For the structure of the organic material axial stretching distributed feedback (DFB) fiber laser hydrophones, both ends are sensitized by the organic material perfusion molding. During encapsulation, when the DFB laser fiber is not precisely fixed to the central axis of the sleeve, the fiber will produce eccentricity after the organic matters are solidified. Therefore, the theoretical model of eccentricity was established in this paper, and the influence of eccentricities on frequency response characteristics of hydrophones was analyzed with the finite element method, and the experimental verification was carried out. Simulation and experimental results indicated that this eccentricity will reduce the sensitivity of DFB fiber laser hydrophones about 2 dB and increase the frequency response fluctuation about 3 dB, which is the key factor to be controlled in the packaging process.
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Dai, Yu Jie. "Hydrodynamic Characteristics of Dislocated Floating Ring Bearing with Different Eccentricities". Applied Mechanics and Materials 52-54 (marzec 2011): 152–55. http://dx.doi.org/10.4028/www.scientific.net/amm.52-54.152.
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For obtain the effect of floating ring radius R2 and floating ring velocity v2 on internal friction in dislocated floating ring with different eccentricities, the evolution of internal friction is simulated with boundary element method (BEM). Numerical simulation results show that internal friction increases with the increase of eccentricity. Internal friction rises linearly as the addition of floating ring velocity v2 if the eccentricity e and radius R2 are fixed. When the velocity v2 is a constant and the range of R2 is 0.75<R2<0.8, the internal friction increase enormously.
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Abderrahim, Touil, Babaa Fatima, Bennis Ouafae i Kratz Frederic. "Analytical Model for Separated Frequency Signature of Outer Race Bearing Fault From Static Eccentricity". International Journal of Circuits, Systems and Signal Processing 15 (11.01.2022): 1821–27. http://dx.doi.org/10.46300/9106.2021.15.196.
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The present paper addresses a precise and an accurate mathematical model for three-phase squirrel cage induction motors, based on winding function theory. Through an analytical development, a comparative way is presented to separate the signature between the existence of the outer race bearing fault and the static eccentricity concerning the asymmetry of the air gap between the stator and the rotor. This analytical model proposes an effective signature of outer race defect separately from other signatures of static eccentricity. Simulation and experimental results are presented to validate the proposed analytical model.
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Jin, Mei, Min Zhang, Gang Wang, Suning Liang, Chongyou Wu i Ruiyin He. "Analysis and Simulation of Wheel-Track High Clearance Chassis of Rape Windrower". Agriculture 12, nr 8 (3.08.2022): 1150. http://dx.doi.org/10.3390/agriculture12081150.
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The middle and lower reaches of the Yangtze River are the main production area of rapeseed. Small windrowers with two tracks are adopted in this area, which have lower efficiency. With the advancement of large-scale rape planting, medium and large windrowers are urgently needed; however, most medium and large windrowers are wheeled machines which have poor adaptability to sticky soil in rice–rape rotation areas. Therefore, a wheel-track high clearance chassis for rape windrower was developed. Theoretical analysis and simulation of the main performance of this chassis were investigated. Mathematical models of the relationship between the chassis eccentricity and running resistance, uphill and downhill angle and the height of obstacle were established. Then, three-dimensional modeling and dynamic simulations of a wheel-track high clearance chassis of a rape windrower in wet clay soil were carried out based on Pro/E and RecurDyn software. The simulation results indicated that when the chassis ran on flat hard road at the same speed, eccentricity had little effect on average walking speed; the coefficient variation of speed decreased with the increase of eccentricity, while the driving torque and its coefficient variation decreased first and then increased. The minimum driving torque and the coefficient variations were obtained when the eccentricities were 1484 mm and 1584 mm. Field experiments were carried out on two kinds of ground. The results showed that on flat hard road, the speed of the wheel-track high clearance rape windrower was 0~20.22 km/h, the minimum turning radius was 5.965 m; on rice stubble field with 38.7% water content, the working speed was 0~9.12 km/h, the minimum turning radius was 6.498 m, and the climbing angle was over 20°. All parameters of the wheel-track high clearance chassis met the design specifications, and the working efficiency increased over 100% compared with the existing two-tracked rape windrower. A new kind of rape windrower for the middle and lower reaches of the Yangtze River was provided.
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Xiao, Chenglong, Renshu Yang, Chenxi Ding, Cheng Chen, Yong Zhao, Yiqiang Kang i Guoli Shi. "Dynamic Fracture Experiment of Medium with Defects under Impact Loading". Shock and Vibration 2021 (16.02.2021): 1–9. http://dx.doi.org/10.1155/2021/8860929.
Pełny tekst źródłaStreszczenie:
Defects have a significant effect on the dynamic fracture characteristics of the medium. In this paper, the dynamic fracture experiment of specimens with bias precracks is designed by utilizing the digital laser dynamic caustics system, and the effect of defect eccentricity on the dynamic fracture behavior is studied. Research shows that crack propagation can be divided into four stages: crack initiation stage, attraction stage, repulsion stage, and specimen fracture stage. The change of defect eccentricity has no obvious effect on the crack propagation behavior in the crack initiation stage and penetration stage but has a significant effect on the attraction stage and specimen fracture stage. In the process of the interaction between defect and crack, mode I stress intensity factor decreases at first and then increases. The decrease of mode I stress intensity factor reduces with the increase of defect eccentricity. The value of mode II stress intensity factor changes from negative to positive. With the increase of defect eccentricity, the symbol of mode II stress intensity factor no longer changes. The fractal dimension and the deflection angle of crack trajectory both decrease with the increase of defect eccentricity. In addition, a numerical simulation of the experiment is conducted by ABAQUS, which provides results that are in good agreement with the experimental results.
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Danko, Jakub, i Vincent Šoltés. "Portfolio creation using graph characteristics". Investment Management and Financial Innovations 15, nr 1 (22.02.2018): 180–89. http://dx.doi.org/10.21511/imfi.15(1).2018.16.
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The aim of this work is by combination of the graph theory and Markowitz portfolio theory to illustrate how some graph characteristics are related to the diversification potential of individual portfolio-forming stocks. Using the graph characteristic, the vertex eccentricity, individual stocks are divided into two groups: a group of large and group of small eccentricity. Eccentricity in this context is considered to be a very suitable metric of the centrality of individual vertices. Different price histories (5 to 30 years) of the Standard and Poor’s index are analyzed. Using the simulation analysis, samples of mentioned groups are generated and then tested by means of comparison to show that larger eccentricity samples, representing stocks on the periphery of the minimum spanning tree of the graph, have a higher potential for diversification than those found in the center of the graph. The results published in the article can be a practical guide for an individual investor during the portfolio creation process and help him/her with decision-making about stock selection.