scholarly journals Beer mats make bad frisbees

2021 ◽  
Vol 136 (7) ◽  
Author(s):  
Johann Ostmeyer ◽  
Christoph Schürmann ◽  
Carsten Urbach
Keyword(s):  
Approximate Solution ◽  
High Speed ◽  
Center Of Mass ◽  
Effective Theory ◽  
High Speed Camera ◽  
Minimal Set ◽  
Crucial Effect ◽  
Forward Edge ◽  
Theoretical Results ◽  
Good Agreement

AbstractIn this article we show why flying and rotating beer mats, CDs, or other flat disks will eventually flip in the air and end up flying with backspin, thus, making them unusable as frisbees. The crucial effect responsible for the flipping is found to be the lift attacking not in the center of mass but slightly offset to the forward edge. This induces a torque leading to a precession towards backspin orientation. An effective theory is developed providing an approximate solution for the disk’s trajectory with a minimal set of parameters. Our theoretical results are confronted with experimental results obtained using a beer mat shooting apparatus and a high speed camera. Very good agreement is found.

scholarly journals Analysis of the Displacement of Thin-Walled Workpiece Using a High-Speed Camera during Peripheral Milling of Aluminum Alloys

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4771
Author(s):  
Jakub Czyżycki ◽  
Paweł Twardowski ◽  
Natalia Znojkiewicz
Keyword(s):  
Aluminum Alloys ◽  
High Speed ◽  
Cutting Parameters ◽  
Displacement Sensor ◽  
Laser Sensor ◽  
High Speed Camera ◽  
The Finite Element Method ◽  
Peripheral Milling ◽  
Thin Walled ◽  
Theoretical Results

The paper presents the possibilities of a high-speed camera in recording displacements of thin-walled workpiece during milling made of aluminum alloys, which allowed for an analysis in which it was compared to other methods of testing the deflection of such elements. The tests were carried out during peripheral milling with constant cutting parameters. Deflection of thin-walled workpiece due to cutting forces was measured using a high-speed camera and a laser displacement sensor. Additionally, the experimental results were compared with the theoretical results obtained with the use of the finite element method. The research proved the effectiveness of the use of high-speed camera in diagnostics of thin-walled workpieces during milling with an accuracy of up to 11% compared to measurements made with a displacement laser sensor.

J/ψ PRODUCTION IN A GLAUBER MONTE CARLO FRAMEWORK

2010 ◽  
Vol 25 (05) ◽  
pp. 1009-1018 ◽  
Author(s):  
HONG-MIN WANG ◽  
ZHAO-YU HOU ◽  
BEN-AI ZHANG ◽  
XIAN-JING SUN
Keyword(s):  
Experimental Data ◽  
Monte Carlo ◽  
Center Of Mass ◽  
Nuclear Modification Factor ◽  
Center Of Mass Energy ◽  
Modification Factor ◽  
Energy Formula ◽  
Theoretical Results ◽  
Monte Carlo Framework ◽  
Good Agreement

By means of a Glauber Monte Carlo framework, the J/ψ production at RHIC energies is studied with the EKS98, EPS09 and HKN07 shadowing parameters. With a χ2 analysis of the experimental data given by PHENIX, a significant dependence of the absorption cross-section, σ abs , on the J/ψ-nucleon center-of-mass energy, [Formula: see text], is revealed with the HKN07 shadowing, but an unconspicuous dependence is shown with the EKS98 and EPS09 shadowing. In this paper, the nuclear modification factor Rd Au vs y, pT and N coll are also calculated and the theoretical results are in good agreement with the experimental data.

Surface Roughness Effects in High-Speed Hydrodynamic Journal Bearings

1997 ◽  
Vol 119 (4) ◽  
pp. 776-780 ◽  
Author(s):  
H. Hashimoto
Keyword(s):  
Surface Roughness ◽  
High Speed ◽  
Reynolds Equation ◽  
Computation Time ◽  
Experimental Results ◽  
Roughness Effects ◽  
Modified Reynolds Equation ◽  
Nonlinear Simultaneous Equations ◽  
Theoretical Results ◽  
Good Agreement

This paper describes an applicability of modified Reynolds equation considering the combined effects of turbulence and surface roughness, which was derived by Hashimoto and Wada (1989), to high-speed journal bearing analysis by comparing the theoretical results with experimental ones. In the numerical analysis of modified Reynolds equation, the nonlinear simultaneous equations for the turbulent correction coefficients are greatly simplified to save computation time with a satisfactory accuracy under the assumption that the shear flow is superior to the pressure flow in the lubricant films. The numerical results of Sommerfeld number and attitude angle are compared with the experimental results to confirm the applicability of the modified Reynolds equation in the case of two types of bearings with different relative roughness heights. Good agreement was obtained between theoretical and experimental results.

Kinematics in a Diffracted Wave Field: Particle Image Velocimetry (PIV) and Numerical Models

2005 ◽  
Author(s):  
Trygve Kristiansen ◽  
Rolf Baarholm ◽  
Geir J. Ro̸rtveit ◽  
Ernst W. Hansen ◽  
Carl Trygve Stansberg
Keyword(s):  
Potential Theory ◽  
High Speed ◽  
Numerical Models ◽  
Vertical Cylinder ◽  
Industrial Applications ◽  
Second Order ◽  
Surface Elevation ◽  
High Speed Camera ◽  
Non Linear ◽  
Theoretical Results

As the use of CFD in industrial applications increases, so does the need for verification and validation of the theoretical/numerical results. This paper focuses on tools for validation and in particular, on the use of Particle Imaging Velocimetry (PIV) as such a tool. Diffraction of regular waves due to a single, fixed vertical cylinder is investigated. Theoretical results of wave run-up and wave kinematics are compared to measurements from model tests. Theoretical results are obtained by second order potential theory and by fully non-linear CFD computations. The second order potential theory frequency-domain results are computed by the industry standard code WAMIT, while the fully nonlinear time-domain simulations are performed by the commercial CFD code Flow-3D. Measurements are obtained by means of wave probes, PIV and snapshots taken with a high-speed camera. The experiments are made with the model in place as well as without the model, for validation of the incident flow field. For the identification of non-linear effects, the steepness of the waves is varied. The surface elevation is measured by means of the wave probes, while the PIV equipment measures the kinematics. High quality photos taken by the high-speed camera give a detailed overview of the surface elevation for inspection. In addition to focusing on validation tools, the paper also addresses some critical aspects associated with the CFD computations, such as the modeling of boundary conditions. The work is based partly upon results from the WaveLand JIP, Phase 2.

Torque and Cavitation Characteristics of Butterfly Valves

1961 ◽  
Vol 28 (4) ◽  
pp. 511-518 ◽  
Author(s):  
Turgut Sarpkaya
Keyword(s):  
Approximate Solution ◽  
Three Dimensional ◽  
Relaxation Technique ◽  
Dimensional Case ◽  
Practical Case ◽  
Two Dimensional ◽  
Actual Flow ◽  
Theoretical Results ◽  
Good Agreement

The present study deals with torque and cavitation characteristics of idealized two-dimensional and axially symmetrical butterfly valves. Theoretical results obtained for the two-dimensional case are compared with the ones obtained experimentally and by a relaxation technique. Based on the results of the two-dimensional case, an approximate solution is presented for the more general and practical case of three-dimensional butterfly valves. The results are in good agreement with the actual flow tests.

Development of Ink-Particle Flight Simulation for Continuous Inkjet Printers

2014 ◽  
Vol 136 (5) ◽  
Author(s):  
Masato Ikegawa ◽  
Eiji Ishii ◽  
Nobuhiro Harada ◽  
Tsuneaki Takagishi
Keyword(s):  
Fluid Dynamics ◽  
Electric Field ◽  
Drag Force ◽  
High Speed ◽  
Electrostatic Force ◽  
Flight Simulation ◽  
High Speed Camera ◽  
Inkjet Printers ◽  
Simulation Results ◽  
Good Agreement

A method of simulating ink-particle flight for industrial, continuous inkjet printers (CIJPs) was developed to clarify the factors that influence print distortion. Print distortion is produced by aerodynamic and electric interference between the ink-particles flying from the nozzle onto the print target. The necessary functions to do this, such as the calculation of electrostatic force in the electric field between the electrodes, Coulomb's force from other charged ink-particles, and the drag force in the inkjet stream for many flying ink-particles were added to a Lagrangian method in the software to analyze the fluid dynamics that was used in the simulations. The trajectories of the ink particles flying from the nozzle onto the print target and the air flow caused by them were simultaneously calculated in the simulations. The results from simulations for the velocities and trajectories of the flying ink particles were compared with the experimental ones obtained with a high-speed camera. These simulation results were in good agreement with the experimental ones, and the developed simulation helps to clarify the factors that influence print distortion and to create algorithms that decrease it.

THE KINEMATIC DIFFERENCES OF THREE TYPES OF CROUCHED POSITIONS DURING A SPRINT START

2016 ◽  
Vol 16 (07) ◽  
pp. 1650099 ◽  
Author(s):  
YO CHEN ◽  
KUANG-YA WU ◽  
YU-JU TSAI ◽  
WEN-TIEN YANG ◽  
JIA-HAO CHANG
Keyword(s):  
Repeated Measures ◽  
High Speed ◽  
Sagittal Plane ◽  
Center Of Mass ◽  
Step Length ◽  
Linear Velocity ◽  
High Speed Camera ◽  
Starting Position ◽  
The Difference ◽  
The Ideal

This study identifies the optimal crouched starting positions (elongated, medium, or bunched) from push-off to the first two steps. Seven elite sprinters were recruited as participants in this study (aged: 21[Formula: see text][Formula: see text][Formula: see text]2 years). A high-speed camera (250[Formula: see text]Hz) was used to collect motion-based images on a sagittal plane. Kwon3D (software) was used to analyze the center of mass (COM) movement, step length, foot linear velocity, take-off angle, and trunk angle. Participants were tested in a 60[Formula: see text]m sprint for bunched, medium, and elongated starting positions. A one-way analysis of variance (ANOVA) ([Formula: see text]) with repeated measures was performed to determine the difference in kinematics in the three crouched starting positions. The LSD comparison was applied to examine differences among pairs of means. Our results indicated that the medium starting position demonstrated a greater first step length and foot linear velocity when compared to the bunched starting position. In the first step toe-off, a lower COM vertical velocity was observed in the medium starting position when compared with the elongated starting position. This study concluded that the medium starting position was the ideal starting position.

Design, fabrication and characterization of an electrical-explosively actuated MEMS flyer-accelerator inserted with parallel bridge foils

2020 ◽  
Vol 91 (1) ◽  
pp. 10301
Author(s):  
Zhi Yang ◽  
Guoqiang Zheng ◽  
Peng Zhu ◽  
Cong Xu ◽  
Qiu Zhang ◽  
...  
Keyword(s):  
High Speed ◽  
Electrical Explosion ◽  
Enhancement Effect ◽  
High Speed Camera ◽  
And Shock Waves ◽  
Test Circuit ◽  
Mems Technology ◽  
Fabrication And Characterization ◽  
Good Agreement

Parallel bridge foils (PBF) with four strip foils, which is derived from traditional single bridge foil (SBF), was designed to study the effect of convergence and collision of plasmas and shock waves on driving flyer. Firstly, Electro-thermal simulation of PBF was performed to analyze temperature distribution before melting, which predicted the synchronous burst characteristic of PBF. Subsequently, a capacitor discharging circuit was designed to initiate bridge foils, results indicated PBF reached higher burst power in shorter time compared with SBF due to better matching between PBF and the test circuit. The flow fields of electrical explosion of bridge foils were photographed by ultra-high-speed camera, which displayed PBF almost burst simultaneously. Moreover, PBF had wider and brighter flow field visualization than SBF owing to convergence and superposition of plasma beams. Most importantly, flyer-accelerators inserted with bridge foils were prepared by MEMS technology, and comparative analysis from PDV revealed MEMS flyer-accelerator inserted with PBF had access to better velocity performances, compared with that inserted with SBF. For instance, PBF flyer-accelerator spent mere 168 ns to 2325 m/s at 900 V/0.22 µF, but SBF flyer-accelerator took 335 ns to 1073 m/s. Finally, we proposed a mathematical model for explaining the enhancement effect of flyer velocity, which to some extent showed good agreement with experimentation.

scholarly journals Mitigating Large Background in Jet Substructure Observables

2020 ◽  
Vol 235 ◽  
pp. 05002
Author(s):  
Daekyoung Kang ◽  
Yang-Ting Chien ◽  
Kyle Lee ◽  
Yiannis Makris
Keyword(s):  
Jet Physics ◽  
Effective Theory ◽  
Soft Particle ◽  
Jet Substructure ◽  
Mass Measurements ◽  
New Approach ◽  
Soft Collinear Effective Theory ◽  
Pile Up ◽  
Theoretical Results ◽  
Good Agreement

We discuss a new approach for jet physics analysis by using subtraction between cumulants of jet substructure observables. The subtracted cumulants are insensitive to soft-particle background uncorrelated with the hard process and allow comparisons between theoretical results and experimental measurements without the complication of soft background like underlying and pile-up events. We find our method using jet mass cumulants efficiently eliminates the background in Monte Carlo simulations and ATLAS jet mass measurements and they show a good agreement with our analytic calculations performed using soft-collinear effective theory.

Investigating the Nonlinear Optical Response of Pepper Oil under Low Power Irradiation with Continuous Wave Visible Laser Beam

2020 ◽  
pp. 131-138
Keyword(s):  
Refractive Index ◽  
Nonlinear Refractive Index ◽  
Nonlinear Optical ◽  
Continuous Wave ◽  
Diffraction Integral ◽  
Visible Laser ◽  
Limiting Property ◽  
Kirchhoff Diffraction Integral ◽  
Theoretical Results ◽  
Good Agreement

The nonlinear optical properties of pepper oil are studied by diffraction ring patterns and Z-scan techniques with continuous wave beam from solid state laser at 473 nm wavelength. The nonlinear refractive index of the sample is calculated by both techniques. The sample show high nonlinear refractive index. Based on Fresnel-Kirchhoff diffraction integral, the far-field intensity distributions of ring patterns have been calculated. It is found that the experimental results are in good agreement with the theoretical results. Also the optical limiting property of pepper oil is reported. The results obtained in this study prove that the pepper oil has applications in nonlinear optical devices.

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