scholarly journals Mixing of Particles in a Rotating Drum with Inclined Axis of Rotation

Processes ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. 1688
Author(s):  
Parag Widhate ◽  
Haiping Zhu ◽  
Qinghua Zeng ◽  
Kejun Dong
Keyword(s):  
Area Ratio ◽  
Rotating Drum ◽  
Mixing Index ◽  
Mixing Processes ◽  
Axis Of Rotation ◽  
Processing Power ◽  
Industrial Waste Management ◽  
Pharmaceutical Industries ◽  
Horizontal Drum ◽  
Rotating Drums

Various experimental and numerical studies have been carried out to study the mixing processes inside rotating drums with a horizontal axis of rotation in the past, but little effort has been made to investigate the rotating drums with an inclined axis of rotation, though such inclined drums exist in industrial waste management, food processing, power and pharmaceutical industries. To fill this gap, in this work, the discrete element method was used to study the mixing phenomena of a rotating drum for different angles of inclination from 0° to 15°. It was found that for inclined rotating drums, the whole bed Lacey mixing index is higher than that for the horizontal drum by 7.2% when the angle of inclination is 10°. The mixing index is related to the area ratio of the active region to the whole bed and volumetric fill. Increase in volumetric fill would lead to the decrease of the mixing index. The mixing index and area ratio exhibit similar patterns along the length of the drum for different angles of inclination.

scholarly journals Triggering avalanches by transverse perturbations in a rotating drum

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Vicente Salinas ◽  
Cristóbal Quiñinao ◽  
Sebastián González ◽  
Gustavo Castillo
Keyword(s):  
Hopf Bifurcation ◽  
Theoretical Model ◽  
Order Parameter ◽  
Small Scale ◽  
Rotating Drum ◽  
Governing Parameter ◽  
Stick Slip ◽  
Slip Regime ◽  
Axis Of Rotation

AbstractWe study the role of small-scale perturbations in the onset of avalanches in a rotating drum in the stick-slip regime. By vibrating the system along the axis of rotation with an amplitude orders of magnitude smaller than the particles’ diameter, we found that the order parameter that properly describes the system is the kinetic energy. We also show that, for high enough frequencies, the onset of the avalanche is determined by the amplitude of the oscillation, contrary to previous studies that showed that either acceleration or velocity was the governing parameter. Finally, we present a theoretical model that explains the transition between the continuous and discrete avalanche regimes as a supercritical Hopf bifurcation.

scholarly journals The geometric axial surface profiles of granular flows in rotating drums

2021 ◽  
Vol 121 (5) ◽  
Author(s):  
Elbasher M.E. Ahmed ◽  
I. Govender ◽  
A. Mainza
Keyword(s):  
Free Surface ◽  
Surface Profile ◽  
Rotating Drum ◽  
Cross Sectional ◽  
Axial Segregation ◽  
Wide Range ◽  
Free Surface Profile ◽  
Axial Profile ◽  
Slurry Transport ◽  
Rotating Drums

SYNOPSIS A mechanistic description of axial segregation in rotating drum flows remains an open question. Consequently, optimal mixing of grinding balls and rocks for efficient breakage, maximum production of fines, and slurry transport is seldom achieved. Experimental and numerical studies of granular mixtures in rotating drums identify alternating axial bands that eventually coarsen in the long-term limit. Most models of axial segregation are limited to binary mixtures and cannot always predict the logarithmic coarsening effects observed experimentally. A key missing factor is a robust description of the axial free surface profile that is valid across a wide range of flow regimes. We present a practical model of the axial free surface profile by linking it to readily-derived geometric features of the cross-sectional S-shaped free surface profile. A parametric study shows good agreement with experimental measurements reported in the literature and heuristically valid trends. Keywords: rotating drum, granular flow, axial profile, comminution, mixing, segregation.

Experimental and DEM studies on the particle mixing performance in rotating drums: Effect of area ratio

2017 ◽  
Vol 314 ◽  
pp. 182-194 ◽  
Author(s):  
Xiangwu Xiao ◽  
Yuanqiang Tan ◽  
Hao Zhang ◽  
Rong Deng ◽  
Shengqiang Jiang
Keyword(s):  
Area Ratio ◽  
Mixing Performance ◽  
Particle Mixing ◽  
Rotating Drums

scholarly journals Particle velocity profile in an inclined rotating drum

2021 ◽  
Vol 249 ◽  
pp. 14001
Author(s):  
P. Widhate ◽  
H. P. Zhu ◽  
Q. H. Zeng ◽  
K. J. Dong
Keyword(s):  
Velocity Profile ◽  
Discrete Element Method ◽  
Particle Velocity ◽  
Average Velocity ◽  
Velocity Profiles ◽  
Average Particle ◽  
Rotating Drum ◽  
Process Industries ◽  
Numerical Studies ◽  
Rotating Drums

Various experimental and numerical studies have been carried out to study the velocity profiles of the particles inside horizontal rotating drums, but little emphasis has been laid on inclined rotating drums, though these drums are extensively used in granular process industries. In this study, velocity profiles of the particles in a rotating drum with 0o, 5o, 10o, and 15o inclinations have been studied by using the discrete element method. It was found that at the locations of the drum with the volumetric fill in the range of 0.2 0.8, the inclined rotating drum has a similar variation of velocity with the radial height to the horizontal rotating drum. However, the variation of the average particle velocity along the length of the drum differs for horizontal and inclined drums. Furthermore, for the inclined rotating drum, the average velocity increases with the increase in the volumetric fill.

scholarly journals Pharmaceutical Industrial Waste Regulation in Five Countries in Asia

2021 ◽  
Vol 3 (1) ◽  
pp. 9
Author(s):  
Luthfia Azzahra ◽  
Nyi Mekar Saptarini
Keyword(s):  
Waste Management ◽  
Industrial Waste ◽  
Safe Disposal ◽  
State Regulations ◽  
Factors Affecting ◽  
Pharmaceutical Waste ◽  
Industrial Waste Management ◽  
Pharmaceutical Industries ◽  
Who Guideline ◽  
Regulations And Guidelines

The pharmaceutical industry produces a various toxic wastes. Generated waste increases the risk of environmental and ecosystem pollution. It is necessary to have proper waste management to prevent waste pollution to the environment. In 1999, WHO published “Guidelines for the Safe Disposal of Unwanted Pharmaceuticals in and after Emergencies”, that contain treatments and safe disposal method, which is appropriate for any country. Many countries had developed and published regulations and guidelines on waste management. This article aimed to review the handling of pharmaceutical industrial waste in five countries in Asia. This review included studies from ProQuest, Crossref, and Google Scholar.  The pharmaceutical industries in Indonesia, India, Japan, Thailand, and China has their own state regulations in order to protect the environment. They also had implemented pharmaceutical industrial waste management following their regulation and guidelines. The method used to treat the waste is similar with WHO guideline. Some factors affecting the country regulations are the insufficient of land and waste management facilities, lack of awareness, low penalties, limited infrastructures, lack of waste testing facilities. The challenge in the future to handle pharmaceutical waste are increasing waste volume, decreasing land for waste management, sewer methods may contaminate water, possible air pollution due to incineration, so it is necessary to have more advanced methods in waste management that are safe for the environment and humans.Keywordz: Industry, Pharmaceutical, Waste Regulation, Asia

On Variations in the Chandler Frequency

1972 ◽  
Vol 1 ◽  
pp. 77-85
Author(s):  
H.J.M. Abraham ◽  
J.N. Boots
Keyword(s):  
Axis Of Rotation ◽  
The Earth ◽  
Actual Motion ◽  
Chandler Frequency

This paper suggests that some of the reported changes in the Chandler frequency are associated with inelastic changes in the Earth. There has been controversy as to how much of the apparent secular polar drift is due to actual motion of the axis of rotation within the Earth, and how much it is merely the reflection of movements by certain observatories. Therefore, when more southern data are available it will be interesting to see whether similar results are obtained.

Reference Coordinate System Requirements for Geophysics

1975 ◽  
Vol 26 ◽  
pp. 87-92
Author(s):  
P. L. Bender
Keyword(s):  
Coordinate System ◽  
Polar Motion ◽  
Main Part ◽  
Measurement Techniques ◽  
Reference Points ◽  
Angular Motion ◽  
Coordinate Systems ◽  
Axis Of Rotation ◽  
The Earth ◽  
Fixed System

AbstractFive important geodynamical quantities which are closely linked are: 1) motions of points on the Earth’s surface; 2)polar motion; 3) changes in UT1-UTC; 4) nutation; and 5) motion of the geocenter. For each of these we expect to achieve measurements in the near future which have an accuracy of 1 to 3 cm or 0.3 to 1 milliarcsec.From a metrological point of view, one can say simply: “Measure each quantity against whichever coordinate system you can make the most accurate measurements with respect to”. I believe that this statement should serve as a guiding principle for the recommendations of the colloquium. However, it also is important that the coordinate systems help to provide a clear separation between the different phenomena of interest, and correspond closely to the conceptual definitions in terms of which geophysicists think about the phenomena.In any discussion of angular motion in space, both a “body-fixed” system and a “space-fixed” system are used. Some relevant types of coordinate systems, reference directions, or reference points which have been considered are: 1) celestial systems based on optical star catalogs, distant galaxies, radio source catalogs, or the Moon and inner planets; 2) the Earth’s axis of rotation, which defines a line through the Earth as well as a celestial reference direction; 3) the geocenter; and 4) “quasi-Earth-fixed” coordinate systems.When a geophysicists discusses UT1 and polar motion, he usually is thinking of the angular motion of the main part of the mantle with respect to an inertial frame and to the direction of the spin axis. Since the velocities of relative motion in most of the mantle are expectd to be extremely small, even if “substantial” deep convection is occurring, the conceptual “quasi-Earth-fixed” reference frame seems well defined. Methods for realizing a close approximation to this frame fortunately exist. Hopefully, this colloquium will recommend procedures for establishing and maintaining such a system for use in geodynamics. Motion of points on the Earth’s surface and of the geocenter can be measured against such a system with the full accuracy of the new techniques.The situation with respect to celestial reference frames is different. The various measurement techniques give changes in the orientation of the Earth, relative to different systems, so that we would like to know the relative motions of the systems in order to compare the results. However, there does not appear to be a need for defining any new system. Subjective figures of merit for the various system dependon both the accuracy with which measurements can be made against them and the degree to which they can be related to inertial systems.The main coordinate system requirement related to the 5 geodynamic quantities discussed in this talk is thus for the establishment and maintenance of a “quasi-Earth-fixed” coordinate system which closely approximates the motion of the main part of the mantle. Changes in the orientation of this system with respect to the various celestial systems can be determined by both the new and the conventional techniques, provided that some knowledge of changes in the local vertical is available. Changes in the axis of rotation and in the geocenter with respect to this system also can be obtained, as well as measurements of nutation.

The spindle stage: A powerful optical tool

1988 ◽  
Vol 46 ◽  
pp. 52-53
Author(s):  
Mickey E. Gunter ◽  
F. Donald Bloss
Keyword(s):  
Significant Error ◽  
Optical Data ◽  
Refractive Indices ◽  
Axis Of Rotation ◽  
Polarizing Microscope ◽  
Microscope Stage

A single, reasonably homogeneous, nonopaque 30-to-300 μm crystal, mounted on a spindle stage and studied by immersion methods under a polarizing microscope, yields optical data frequently sufficient to identify and characterize a substance unequivocally. The data obtainable include (1) the orientation of the crystal's principal vibration axes and (2) its principal refractive indices, to within 0.0002 if desired, for light vibrating along these principal vibration axes. Spindle stages tend to be simple and relatively inexpensive, some costing less than $50. They permit rotation of the crystal about a single axis which is parallel to the microscope stage. This spindle or S-axis is thus perpendicular to the M-axis, namely the microscope stage's axis of rotation.A spindle stage excels when studying anisotropic crystals. It orients uniaxial crystals within minutes and biaxial crystals almost as quickly so that their principal refractive indices - ɛ and ω (uniaxial); α, β and γ (biaxial) - can be determined without significant error from crystal misorientation.

Carum copticum L. essential oils as natural antimicrobial and antioxidant

2018 ◽  
Vol 44 (4) ◽  
pp. 515-520
Author(s):  
M Kazemi
Keyword(s):  
Essential Oils ◽  
Radical Scavenging Activity ◽  
Radical Scavenging ◽  
Dpph Radical ◽  
Dpph Radical Scavenging Activity ◽  
Carum Copticum ◽  
Microbial Strains ◽  
Pharmaceutical Industries ◽  
Dpph Radical Scavenging ◽  
Antioxidant Effects

Carum copticum L. comprises several relevant species for food, cosmetic, perfumery and pharmaceutical industries. GC/MS analysis of the enential oil of C. copticum revealed γ- terpinene as a major component of C. copticum, with its contribution of 33.85%. Essential oils (EOs) exhibited a significant antimicrobial activity against all tested microbial strains. In addition, the C. copticum oil demonstrated the highest DPPH radical scavenging activity. These results clearly show the antimicrobial and antioxidant effects of the plant essential oil.

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