scholarly journals Numerical Investigation on the Sieving Performance of Elliptical Vibrating Screen

Processes ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 1151
Author(s):  
Zhiquan Chen ◽  
Xin Tong ◽  
Zhanfu Li
Keyword(s):  
Major Axis ◽  
The Finite Element Method ◽  
Semi Major Axis ◽  
Vibration Direction ◽  
Maximum Deformation ◽  
Vibrating Screen ◽  
Performance Indexes ◽  
Screening Efficiency ◽  
Axis Length ◽  
Element Method

Screening techniques have been widely deployed in industrial production for the size-separation of granular materials such as coal. The elliptical vibrating screen has been regarded as an excellent screening apparatus in terms of its high screening efficiency and large processing capacity. However, its fundamental mechanisms and operational principles remain poorly understood. In this paper, the sieving process of an elliptical vibrating screen was numerically simulated based on the discrete element method (DEM), and an approach coupling the DEM and the finite element method (DEM–FEM) was introduced to further explore the collision impact of materials on the screen deck. The screening time, screening efficiency, maximum stress and maximum deformation were examined for the evaluation of sieving performance. The effects of six parameters—length of the semi-major axis, length ratio between two semi-axes, vibration frequency, inclination angle, vibration direction angle and vibration direction—on different sieving results were systematically investigated in univariate and multivariate experiments. Additionally, the relationships among the four performance indexes were discussed and the relational functions were obtained. The conclusions and methodologies presented in this work could be of great significance for the design and improvement of elliptical vibrating screens.

Numerical simulation of particle screening efficiency of large multi-layer vibrating screen based on discrete element method

2021 ◽  
pp. 095440892110606
Author(s):  
Yujia Li ◽  
Peng Zhao ◽  
Li Mo ◽  
Tao Ren ◽  
Minghong Zhang
Keyword(s):  
Discrete Element Method ◽  
Environmental Protection ◽  
Inclination Angle ◽  
Discrete Element ◽  
Physical Parameters ◽  
Screening Process ◽  
Efficient Operation ◽  
Vibrating Screen ◽  
Screening Efficiency ◽  
Element Method

With the increasing requirements for energy conservation and environmental protection, multi-layer vibrating screens have become hot issues. Compared with single-layer vibrating screens, multi-layer vibrating screens has much better performance in terms of processing effect, treatment capacity, and environmental protection. The research on the physical parameters of the multi-layer vibrating screen is of great significance to the actual production. However, analysis and simulation studies of multi-layer vibrating screens are limited. In this paper, the screening process of wet particles on a multi-layer vibrating screen was simulated by using the discrete element method. The characteristics and application scope of the two vibration modes were analyzed. The particle penetration rate, the number of collisions, and the distribution of the particles under 23 combinations of structures and vibration parameters were investigated. The influence of different parameters on screening performance was analyzed. Several optimal combinations of frequency, amplitude and screen inclination angle under different working conditions were obtained. The screening efficiency of the balanced elliptic motion is higher than that of the linear motion. The best combination of the three parameters is 4 mm amplitude, 20 Hz frequency, and 3° inclination angle. The efficiency is higher when the particles follow a distribution of arithmetic on the screen. This study provides a reference for the efficient operation and optimal design of large multi-layer screening equipment.

scholarly journals The Central Bar in M 94

1996 ◽  
Vol 171 ◽  
pp. 422-422
Author(s):  
C. Möllenhoff ◽  
M. Matthias ◽  
O.E. Gerhard
Keyword(s):  
Major Axis ◽  
Stellar Kinematics ◽  
Semi Major Axis ◽  
Ionized Gas ◽  
Model Calculations ◽  
Gas Kinematics ◽  
Closed Orbits ◽  
Total Light ◽  
Axis Length ◽  
Global And Local

Surface photometry in I, J, K of the oval disk galaxy M 94 (NGC 4736) reveal a weak central stellar bar of 0.7 kpc semi-major axis length, comprising ≈ 14% of the total light within 20″. By stellar kinematics the existence of a small spheroidal bulge with v/à ≈ 0.8 was discovered. The ionized gas (Hα) in this region shows global and local deviations from the stellar kinematics. Model calculations of closed orbits for the cold gas in the combined potential of bar, disk, and bulge predict large non-circular motions in equilibrium flow. However, these do not fit the observed gas kinematics; obviously hydrodynamical forces play a role in the central region of M 94.

scholarly journals Internal ballistics of polygonal and grooved barrels: A comparative study

2021 ◽  
Vol 104 (2) ◽  
pp. 003685042110169
Author(s):  
Usiel S Silva-Rivera ◽  
Luis Adrian Zúñiga-Avilés ◽  
Adriana H Vilchis-González ◽  
Pedro A Tamayo-Meza ◽  
Wilbert David Wong-Angel
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Comparative Study ◽  
Experimental Tests ◽  
Loading Conditions ◽  
The Finite Element Method ◽  
Maximum Deformation ◽  
Internal Ballistics ◽  
Internal Deformation ◽  
Element Method

As a parameter important ballistic, the research about polygonal and grooved barrels’ behavior has not been widely carried out. The pressures, velocities, stresses, deformations, and strains generated by the firing of 9 mm × 19 mm ammunition in weapons with polygonal barrels are analyzed numerically and experimentally, compared with those generated in pistols with grooved barrels. The Finite Element Method with equal boundary and loading conditions was used in both types of guns, specifying the actual materials of the projectile and the barrels. Subsequently, experimental tests were carried out on various weapons with 9 mm ammunitions of 115, 122, and 124 gr. The results show that the 9 mm bullet fired in a polygonal barrel undergoes a maximum deformation towards its exterior of 0.178 mm and interior of 0.158 mm, with stress up to 295.85 MPa. Compared with 0.025 mm maximum external deformation and 0.112 mm internal deformation of 9 mm projectiles fired in a grooved barrel, with stress up to 269.79 MPa. The deformation in the polygonal barrel is in a greater area, but the rifling impression left is less deep, making its identification more difficult. Although there are differences in the stresses and strains obtained, similar velocity and pressure parameters are achieved in the two types of barrels. This has application in the development and standardization of new kinds of barrels and weapons.

scholarly journals Numerical analysis of stresses at oblique holes in plates subjected to tension and bending

1995 ◽  
Vol 30 (4) ◽  
pp. 317-323 ◽  
Author(s):  
A Tafreshi ◽  
T E Thorpe
Keyword(s):  
Finite Element ◽  
Uniaxial Tension ◽  
Plate Thickness ◽  
Major Axis ◽  
Hole Diameter ◽  
The Finite Element Method ◽  
Flat Plates ◽  
Out Of Plane ◽  
Stress Concentration Factors ◽  
Element Method

Stress analysis of a series of thick, wide, flat plates with oblique holes subjected to uniaxial tension and out-of-plane bending has been carried out using the finite element method (FEM), and in some cases the boundary element method (BEM). Different plate thickness-hole diameter ratios, angles of hole obliquity and orientation have been considered to provide stress concentration factors at such holes. The work covers plate thickness-hole diameter ratios from 1.3 to 3.0, hole obliquity angles from 0 to 60° and orientation of the major axis of the surface ellipse relative to the applied load direction of 0 to 90°. The results for uniaxial tension have been compared with those determined using the photoelastic frozen-stress technique in order to verify the finite element models before proceeding to the bending cases, which provide new data.

The Motion of a Neutrally Buoyant Ellipsoid Inside Square Tube Flows

2017 ◽  
Vol 9 (2) ◽  
pp. 233-249 ◽  
Author(s):  
Xin Yang ◽  
Haibo Huang ◽  
Xiyun Lu
Keyword(s):  
Major Axis ◽  
Prolate Spheroid ◽  
Small Displacement ◽  
Semi Major Axis ◽  
Stable Mode ◽  
Axis Length ◽  
Diagonal Plane ◽  
Rolling Mode ◽  
Boltzmann Method ◽  
Rectangular Tubes

AbstractThe motion and rotation of an ellipsoidal particle inside square tubes and rectangular tubes with the confinement ratio R/a∈(1.0,4.0) are studied by the lattice Boltzmann method (LBM), where R and a are the radius of the tube and the semi-major axis length of the ellipsoid, respectively. The Reynolds numbers (Re) up to 50 are considered. For the prolate ellipsoid inside square and rectangular tubes, three typical stable motion modes which depend on R/a are identified, namely, the kayaking mode, the tumbling mode, and the log-rolling mode are identified for the prolate spheroid. The diagonal plane strongly attracts the particle in square tubes with 1.2≤R/a<3.0. To explore the mechanism, some constrained cases are simulated. It is found that the tumbling mode in the diagonal plane is stable because the fluid force acting on the particle tends to diminish the small displacement and will bring it back to the plane. Inside rectangular tubes the particle will migrate to a middle plane between short walls instead of the diagonal plane. Through the comparisons between the initial unstable equilibrium motion state and terminal stable mode, it is seems that the particle tend to adopt the mode with smaller kinetic energy.

scholarly journals Space Debris Tracking with the Poisson Labeled Multi-Bernoulli Filter

Sensors ◽  
2021 ◽  
Vol 21 (11) ◽  
pp. 3684
Author(s):  
Leonardo Cament ◽  
Martin Adams ◽  
Pablo Barrios
Keyword(s):  
Major Axis ◽  
Low Earth Orbit ◽  
Spatial Density ◽  
Semi Major Axis ◽  
Admissible Region ◽  
Sensor Field ◽  
Physical Energy ◽  
Multi Target Tracking ◽  
Axis Length ◽  
Tracking Filter

This paper presents a Bayesian filter based solution to the Space Object (SO) tracking problem using simulated optical telescopic observations. The presented solution utilizes the Probabilistic Admissible Region (PAR) approach, which is an orbital admissible region that adheres to the assumption of independence between newborn targets and surviving SOs. These SOs obey physical energy constraints in terms of orbital semi-major axis length and eccentricity within a range of orbits of interest. In this article, Low Earth Orbit (LEO) SOs are considered. The solution also adopts the Partially Uniform Birth (PUB) intensity, which generates uniformly distributed births in the sensor field of view. The measurement update then generates a particle SO distribution. In this work, a Poisson Labeled Multi-Bernoulli (PLMB) multi-target tracking filter is proposed, using the PUB intensity model for the multi-target birth density, and a PAR for the spatial density to determine the initial orbits of SOs. Experiments are demonstrated using simulated SO trajectories created from real Two-Line Element data, with simulated measurements from twelve telescopes located in observatories, which form part of the Falcon telescope network. Optimal Sub-Pattern Assignment (OSPA) and CLEAR MOT metrics demonstrate encouraging multi-SO tracking results even under very low numbers of observations per SO pass.

Micromagnetic simulation of hysteresis loop of elliptic permalloy nanorings

2016 ◽  
Vol 30 (26) ◽  
pp. 1650192 ◽  
Author(s):  
Amaresh Chandra Mishra
Keyword(s):  
Magnetic Field ◽  
Hysteresis Loop ◽  
Magnetic Hysteresis ◽  
Major Axis ◽  
Micromagnetic Simulation ◽  
Hysteresis Curve ◽  
Semi Major Axis ◽  
Axis Length ◽  
20 Nm ◽  
The Magnetic Field

Magnetic hysteresis behavior of isotropic permalloy elliptic nanorings of outer semi-major axis length [Formula: see text] 100 nm and thickness [Formula: see text] 20 nm were studied with respect to the variation of two parameters: outer semiminor axis length [Formula: see text] and the difference between outer and inner dimensions [Formula: see text]. The outer semiminor axis length [Formula: see text] varied from 90 nm to 20 nm which covers from nearly circular nanoring to elliptic nanoring of high aspect ratio. The value of [Formula: see text] varied in steps of 10 nm. Micromagnetic simulation of in-plane hysteresis curve of these nanorings revealed that the remanent state of all of these elliptic rings are onion states if the magnetic field is applied along the longer side of the elliptic rings. If the magnetic field is applied along the shorter side, then the remanent states turn out to be vortex state. The hysteresis loss indicated by area of the hysteresis loop was found to be decreasing gradually with the increment of either [Formula: see text] or [Formula: see text]. On the other hand, the remanent magnetization increased with increment of [Formula: see text] but decreased with the increment of [Formula: see text]. The changes were attributed to three parameters mainly: inner curvature, exchange energy and demagnetization energy. The changes in loop area were discussed in light of variation of these three parameters.

scholarly journals Discovery of a near-infrared bar and a pseudo-bulge in the collisional ring galaxy Cartwheel

2020 ◽  
Vol 497 (1) ◽  
pp. 44-51
Author(s):  
Sudhanshu Barway ◽  
Y D Mayya ◽  
Aitor Robleto-Orús
Keyword(s):  
Morphological Analysis ◽  
Near Infrared ◽  
Hubble Space Telescope ◽  
Major Axis ◽  
Effective Radius ◽  
Semi Major Axis ◽  
Optical Images ◽  
Central Bulge ◽  
Axis Length ◽  
Band Image

ABSTRACT We report the discovery of a bar, a pseudo-bulge, and unresolved point source in the archetype collisional ring galaxy Cartwheel using careful morphological analysis of a near-infrared (NIR) Ks-band image of excellent quality (seeing = 0.42″) at the ESO archive. The bar is oval-shaped with a semi-major axis length of 3.23″ (∼2.09 kpc), with almost a flat light distribution along it. The bulge is almost round (ellipticity = 0.21) with an effective radius of 1.62″ (∼1.05 kpc) and a Sersic index of 0.99, parameters typical of pseudo-bulges in late-type galaxies. The newly discovered bar is not recognizable as such in the optical images even with more than a factor of 2 higher spatial resolution of the Hubble Space Telescope, due to a combination of its red colour and the presence of dusty features. The observed bar and pseudo-bulge most likely belonged to the pre-collisional progenitor of the Cartwheel. The discovery of a bar in an archetype collisional ring galaxy Cartwheel is the first observational evidence to confirm the prediction that bars can survive a drop-through collision along with the morphological structures like a central bulge (pseudo).

Detection and Characterization of earth-like Planets

1997 ◽  
Vol 161 ◽  
pp. 299-311 ◽  
Author(s):  
Jean Marie Mariotti ◽  
Alain Léger ◽  
Bertrand Mennesson ◽  
Marc Ollivier
Keyword(s):  
Direct Detection ◽  
Contrast Ratio ◽  
Angular Size ◽  
Physical Nature ◽  
Major Axis ◽  
Infrared Emission ◽  
Space Technology ◽  
Semi Major Axis ◽  
Earth Like Planets ◽  
Visible Wavelengths

AbstractIndirect methods of detection of exo-planets (by radial velocity, astrometry, occultations,...) have revealed recently the first cases of exo-planets, and will in the near future expand our knowledge of these systems. They will provide statistical informations on the dynamical parameters: semi-major axis, eccentricities, inclinations,... But the physical nature of these planets will remain mostly unknown. Only for the larger ones (exo-Jupiters), an estimate of the mass will be accessible. To characterize in more details Earth-like exo-planets, direct detection (i.e., direct observation of photons from the planet) is required. This is a much more challenging observational program. The exo-planets are extremely faint with respect to their star: the contrast ratio is about 10−10at visible wavelengths. Also the angular size of the apparent orbit is small, typically 0.1 second of arc. While the first point calls for observations in the infrared (where the contrast goes up to 10−7) and with a coronograph, the latter implies using an interferometer. Several space projects combining these techniques have been recently proposed. They aim at surveying a few hundreds of nearby single solar-like stars in search for Earth-like planets, and at performing a low resolution spectroscopic analysis of their infrared emission in order to reveal the presence in the atmosphere of the planet of CO H2O and O3. The latter is a good tracer of the presence of oxygen which could be, like on our Earth, released by biological activity. Although extremely ambitious, these projects could be realized using space technology either already available or in development for others missions. They could be built and launched during the first decades on the next century.

Simulation of tuning graphene plasmonic behaviors by ferroelectric domains for self-driven infrared photodetector applications

Nanoscale ◽  
2019 ◽  
Vol 11 (43) ◽  
pp. 20868-20875 ◽  
Author(s):  
Junxiong Guo ◽  
Yu Liu ◽  
Yuan Lin ◽  
Yu Tian ◽  
Jinxing Zhang ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Interfacial Effect ◽  
Infrared Photodetector ◽  
The Finite Element Method ◽  
Ferroelectric Domains ◽  
Element Method

We propose a graphene plasmonic infrared photodetector tuned by ferroelectric domains and investigate the interfacial effect using the finite element method.

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