scholarly journals DEM Simulation of Laboratory-Scale Jaw Crushing of a Gold-Bearing Ore Using a Particle Replacement Model

Minerals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 717
Author(s):  
Gabriel Kamilo Barrios ◽  
Narcés Jiménez-Herrera ◽  
Silvia Natalia Fuentes-Torres ◽  
Luís Marcelo Tavares
Keyword(s):  
Compressive Force ◽  
Laboratory Scale ◽  
Compression Tests ◽  
Dem Simulation ◽  
Product Size ◽  
Design And Optimization ◽  
Jaw Crusher ◽  
Replacement Model ◽  
Using Data ◽  
Good Agreement

The Discrete Element Method (DEM) is a numerical method that is able to simulate the mechanical behavior of bulk solids flow using spheres or polyhedral elements, offering a powerful tool for equipment design and optimization through modeling and simulation. The present work uses a Particle Replacement Model (PRM) embedded in the software EDEM® to model and simulate operation of a laboratory-scale jaw crusher. The PRM was calibrated using data from single particle slow compression tests, whereas simulations of the jaw crusher were validated on the basis of experiments, with very good agreement. DEM simulations described the performance of the crusher in terms of throughput, product size distribution, compressive force on the jaws surface, reduction ratio, and energy consumption as a function of closed side setting and frequency.

scholarly journals Experimental studies on the transformation from firn to ice in the wet-snow zone of temperate glaciers

1997 ◽  
Vol 24 ◽  
pp. 181-185 ◽  
Author(s):  
Katsuhisa Kawashima ◽  
Tomomi Yamada
Keyword(s):  
Experimental Studies ◽  
Ice Formation ◽  
Compression Tests ◽  
Densification Rate ◽  
Overburden Pressure ◽  
Proportionality Constant ◽  
Wet Snow ◽  
Water Saturated ◽  
The Relationship ◽  
Good Agreement

The densification of water-saturated firn, which had formed just above the firn-ice transition in the wet-snow zone of temperate glaciers, was investigated by compression tests under pressures ranging from 0.036 to 0.173 MPa, with special reference to the relationship between densification rate, time and pressure. At each test, the logarithm of the densification rate was proportional to the logarithm of the time, and its proportionality constant increased exponentially with increasing pressure. The time necessary for ice formation in the firn aquifer was calculated using the empirical formula obtained from the tests. Consequently, the necessary time decreased exponentially as the pressure increased, which shows that the transformation from firn in ice can be completed within the period when the firn aquifer exists, if the overburden pressure acting on the water-saturated firn is above 0.12–0.14 MPa. This critical value of pressure was in good agreement with the overburden pressure obtained from depth–density curves of temperate glaciers. It was concluded that the depth of firn–ice transition was self-balanced by the overburden pressure to result in the concentration between 20 and 30 m.

scholarly journals STATISTICAL STUDIES ON PROTEIN POLYMORPHISM IN NATURAL POPULATIONS II. GENE DIFFERENTIATION BETWEEN POPULATIONS

Genetics ◽  
1978 ◽  
Vol 88 (2) ◽  
pp. 367-390
Author(s):  
Ranajit Chakraborty ◽  
Paul A Fuerst ◽  
Masatoshi Nei
Keyword(s):  
Genetic Differentiation ◽  
Natural Populations ◽  
Drift Theory ◽  
Alternative Hypotheses ◽  
Mean And Variance ◽  
Statistical Studies ◽  
Different Populations ◽  
Using Data ◽  
Almost All ◽  
Good Agreement

ABSTRACT With the aim of testing the validity of the mutation-drift hypothesis, we examined the pattern of genetic differentiation between populations by using data from Drosophila, fishes, reptiles, and mammals. The observed relationship between genetic identity and correlation of heterozygosities of different populations or species was generally in good agreement with the theoretical expectations from the mutation-drift theory, when the variation in mutation rate among loci was taken into account. In some species of Drosophila, however, the correlation was unduly high. The relationship between the mean and variance of genetic distance was also in good agreement with the theoretical prediction in almost all organisms. We noted that both the distribution of heterozygosity within species and the pattern of genetic differentiation between species can be explained by the same set of genetic parameters in each group of organisms. Alternative hypotheses for explaining these observations are discussed.

scholarly journals Modeling the Peach Sugar Contents in Relation to Fruit Growth

1996 ◽  
Vol 121 (6) ◽  
pp. 1122-1131 ◽  
Author(s):  
Michel Génard ◽  
Michel Souty
Keyword(s):  
Growth Curve ◽  
Prunus Persica ◽  
Transfer Functions ◽  
Dry Weight ◽  
Fruit Growth ◽  
Data Sets ◽  
Weight Growth ◽  
Using Data ◽  
Good Agreement

The edible quality of peaches (Prunus persica L. Batsch) to a great extent depends on their sweetness, which is related to sugar composition. Our objective was to develop a model to predict carbon partitioning within fruit flesh and to predict the sucrose, sorbitol, glucose, and fructose contents. The model is dynamic and deterministic and was designed to be driven by the flesh dry-weight growth curve, flesh water content, and temperature data. It uses differential equations where the state of the system is defined by variables that describe how much carbon is present as each form of sugar and as other compounds (acids and structural carbohydrates). The rates of change of these amounts of carbon depend on the current values of corresponding variables and on the transfer functions between them. These functions are defined by rate constants or by functions of degree-days after full bloom. The model was calibrated and tested using data sets from treatments that covered several leaf: fruit ratios. The predictions of the model were in fairly good agreement with experimental data. A sensitivity analysis was performed to identify the most influential transfer function parameters. Carbon flows between sugar forms were analyzed. Sucrose, which was the most abundant sugar, and fructose, which is the sweetest, contributed most to fruit sweetness. Simulations were performed to study the effects of changes in fruit growth-curve parameters on sugar contents and concentrations.

scholarly journals DEM simulation of triaxial compression tests on MHBS under different back pressures

2020 ◽  
Vol 8 (4) ◽  
pp. 126-129
Author(s):  
Mingjing Jiang ◽  
Guangshuai Li ◽  
Wenhao Du ◽  
Xiaofeng Wu ◽  
Pei Cao
Keyword(s):  
Triaxial Compression ◽  
Compression Tests ◽  
Dem Simulation ◽  
Triaxial Compression Tests

Hot Forming Optimization of ZK30 Magnesium Alloy

2018 ◽  
Vol 941 ◽  
pp. 2325-2330 ◽  
Author(s):  
Manuel Carsí ◽  
Fernando Carreño ◽  
Oscar A. Ruano
Keyword(s):  
Magnesium Alloy ◽  
Lyapunov Stability ◽  
Stability Criterion ◽  
Strain Rates ◽  
Optimum Temperature ◽  
Compression Tests ◽  
Deformation Bands ◽  
Lyapunov Stability Criterion ◽  
Reduced Costs ◽  
Using Data

The modeling of the forming of materials at high homologous temperatures allows obtaining optimum forming parameters, reduced costs and improving final properties of the finished product. In this work, the behavior of the ZK30 Magnesium alloy was characterized by means of compression tests at temperatures 300 to 450oC and strain rates between 0.1 and 8.7 s-1. Using data from these tests, the parameters of the Garofalo equation are calculated. In addition, by means of the second Lyapunov stability criterion, the optimum temperature at a given temperature is determined which should minimize the appearance of deformation bands and cracks during hot working. This temperature was found to be 641 K (368oC) at 8.7 s-1.

Quantitative Analysis of Dynamic Softening Behaviors Induced by Dynamic Recrystallization for Ti-10V-2Fe-2Al Alloy

2015 ◽  
Vol 34 (6) ◽  
Author(s):  
Guozheng Quan ◽  
Shiao Pu ◽  
Hairong Wen ◽  
Zhenyu Zou ◽  
Jie Zhou
Keyword(s):  
Titanium Alloy ◽  
Quantitative Analysis ◽  
Dynamic Recrystallization ◽  
Hot Compression ◽  
Laboratory Scale ◽  
Compression Tests ◽  
Temperature Range ◽  
Height Reduction ◽  
Softening Behavior ◽  
Dynamic Softening

AbstractIn order to investigate the effect of dynamic recrystallization (DRX) behavior on dynamic softening behavior of wrought Ti-10V-2Fe-3Al titanium alloy, a series of laboratory scale isothermal hot compression tests with a height reduction of 60% were performed in a temperature range of 948 K~1023 K in the (

Simulating Dynamic Activities Using a Five-Axis Knee Simulator

2005 ◽  
Vol 127 (1) ◽  
pp. 123-133 ◽  
Author(s):  
Lorin P. Maletsky ◽  
Ben M. Hillberry
Keyword(s):  
Sagittal Plane ◽  
Compressive Force ◽  
Knee Prostheses ◽  
Plane Model ◽  
Knee Simulator ◽  
Specific Loading ◽  
Total Knee ◽  
Five Axis ◽  
Cadaveric Knee ◽  
Good Agreement

This work describes the design and capabilities of the Purdue Knee Simulator: Mark II and a sagittal-plane model of the machine. This five-axis simulator was designed and constructed to simulate dynamic loading activities on either cadaveric knee specimens or total knee prostheses mounted on fixtures. The purpose of the machine was to provide a consistent, realistic loading of the knee joint, allowing the kinematics and specific loading of the structures of the knee to be determined based on condition, articular geometry, and simulated activity. The sagittal-plane model of the knee simulator was developed both to predict the loading at the knee from arbitrary inputs and to generate the necessary inputs required to duplicate specified joint loading. Measured tibio-femoral compressive force and quadriceps tension were shown to be in good agreement with the predicted loads from the model. A controlled moment about the ankle-flexion axis was also shown to change the loading on the quadriceps.

Damper force Characteristics of a Separated Dual-chamber Single-rod Type Damper utilizing an Elastomer Particle Assemblage in the Case of both Chambers Containing Particles

2020 ◽  
pp. 1-27
Author(s):  
Atsushi Toyouchi ◽  
Yasushi Ido ◽  
Yuhiro Iwamoto ◽  
Makoto Hanai
Keyword(s):  
Friction Force ◽  
Vibration Frequency ◽  
Compressive Force ◽  
Packing Fraction ◽  
Dual Chamber ◽  
Hard Particles ◽  
Large Hysteresis ◽  
Particle Dampers ◽  
Force Characteristics ◽  
Good Agreement

Abstract Particle dampers that use soft/hard particles are attracting attention as a solution to problems such as oil leakage of oil dampers and the temperature dependence of their characteristics. Particle dampers effectively attenuate vibration using the friction and inelastic normal collisions generated between particles or between particles and walls. Here, the effects of the packing fraction of particles, the vibration frequency, and hardness of the material on the damper force characteristics of a separated dual-chamber single-rod type damper with elastomer particle assemblages were investigated experimentally. The maximal damper force and its hysteresis increased with the packing fraction, the vibration frequency, and the Young's modulus of the particle material. Numerical simulations using the discrete element method were performed to confirm the behavior of the elastomer particles when they were packed in both chambers. The compressive force distribution and velocity vector diagram of particles in the simulations showed that friction and compression between particles due to particle movement, friction between particles and the chamber walls, and the viscosity of the elastomer particles caused a large hysteresis in the damper force. The maximum damper force is affected by the viscoelastic component force and the friction force in the same proportion, and the hysteresis is dominated by the friction force. The simulation results were confirmed to be in good agreement, both qualitatively and quantitatively, with the experimentally measured damper force characteristics.

scholarly journals Performance of WVSS-II hygrometers on the FAAM research aircraft

2015 ◽  
Vol 8 (3) ◽  
pp. 1617-1625 ◽  
Author(s):  
A. K. Vance ◽  
S. J. Abel ◽  
R. J. Cotton ◽  
A. M. Woolley
Keyword(s):  
Liquid Water ◽  
The Other ◽  
Optimal Conditions ◽  
Statistical Assessment ◽  
Free Data ◽  
Variable Nature ◽  
Wide Range ◽  
Research Aircraft ◽  
Using Data ◽  
Good Agreement

Abstract. We compare the performance of five hygrometers fitted to the Facility for Airborne Atmospheric Measurement's (FAAM) BAe 146-301 research aircraft using data from approximately 100 flights executed over the course of 2 years under a wide range of conditions. Bulk comparison of cloud free data show good agreement between chilled mirror hygrometers and a WVSS-II fed from a modified Rosemount inlet, but that a WVSS-II fed from the standard flush inlet appears to over-read compared to the other instruments, except at higher humidities. Statistical assessment of hygrometer performance in cloudy conditions is problematic due to the variable nature of clouds, so a number of case studies are used instead to investigate the performance of the hygrometers in sub-optimal conditions. It is found that the flush inlet is not susceptible to either liquid or solid water but that the Rosemount inlet has a significant susceptibility to liquid water and may also be susceptible to ice. In all conditions the WVSS-II responds much more rapidly than the chilled mirror devices, with the flush inlet-fed WVSS-II being more rapid than that connected to the Rosemount.

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