scholarly journals DEM Parameter Calibration of Maize Seeds and the Effect of Rolling Friction

Processes ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 914
Author(s):  
Long Zhou ◽  
Jianqun Yu ◽  
Liusuo Liang ◽  
Yang Wang ◽  
Yajun Yu ◽  
...  
Keyword(s):  
Rolling Friction ◽  
Angle Of Repose ◽  
Screening Tests ◽  
Maize Seeds ◽  
Seed Particles ◽  
Suitable Parameter ◽  
Highly Sensitive ◽  
Maize Varieties ◽  
Two Parameters ◽  
Parameter Values

A set of suitable parameter values is crucial in discrete element method (DEM) simulations. As a non-spherical particle, the coefficients of rolling friction between maize seed particles and between the seed particles and the boundary are hard to measure directly and must be obtained by calibration. In this paper, taking three representative maize varieties as research objects, the necessity for the accurate calibration of the coefficients of rolling friction between seed particles and between seed particles and boundaries is investigated. Subsequently, by studying the sensitivity of the coefficients of rolling friction between seed particles and between seed particles and the boundary to the angle of repose test, the methods used to calibrate the coefficients of rolling friction between seed particles and between the particles and the boundary are determined. It can be seen from the results that the coefficients of rolling friction between the seed particles and between the seed particles and the boundary have a significant influence on the test results, so these two parameters must be accurately calibrated. Additionally, the coefficient of rolling friction between seed particles and the boundary has no effect on the piling angle, but the piling angle is highly sensitive to the coefficient of rolling friction between seed particles. By comparing the simulation results and the experimental results in the lifting cylinder and “self-flow screening” tests, the calibrated seed parameters were found to be accurate and valid.

scholarly journals Analysis of anticoagulants for blood-based quantitation of amyloid β oligomers in the sFIDA assay

2017 ◽  
Vol 398 (4) ◽  
pp. 465-475 ◽  
Author(s):  
Kateryna Kravchenko ◽  
Andreas Kulawik ◽  
Maren Hülsemann ◽  
Katja Kühbach ◽  
Christian Zafiu ◽  
...  
Keyword(s):  
Blood Plasma ◽  
Limit Of Detection ◽  
Amyloid Β ◽  
Distribution Analysis ◽  
Aβ Oligomers ◽  
Quantitative Measurements ◽  
Suitable Parameter ◽  
Edta Plasma ◽  
Soluble Aβ Oligomers ◽  
Parameter Values

Abstract Early diagnostics at the preclinical stage of Alzheimer’s disease is of utmost importance for drug development in clinical trials and prognostic guidance. Since soluble Aβ oligomers are considered to play a crucial role in the disease pathogenesis, several methods aim to quantify Aβ oligomers in body fluids such as cerebrospinal fluid (CSF) and blood plasma. The highly specific and sensitive method surface-based fluorescence intensity distribution analysis (sFIDA) has successfully been established for oligomer quantitation in CSF samples. In our study, we explored the sFIDA method for quantitative measurements of synthetic Aβ particles in blood plasma. For this purpose, EDTA-, citrate- and heparin-treated blood plasma samples from five individual donors were spiked with Aβ coated silica nanoparticles (Aβ-SiNaPs) and were applied to the sFIDA assay. Based on the assay parameters linearity, coefficient of variation and limit of detection, we found that EDTA plasma yields the most suitable parameter values for quantitation of Aβ oligomers in sFIDA assay with a limit of detection of 16 fM.

Superconductors with spin–orbit interactions

2016 ◽  
Vol 30 (25) ◽  
pp. 1650183 ◽  
Author(s):  
Yu. N. Ovchinnikov
Keyword(s):  
Magnetic Field ◽  
Superconducting Films ◽  
Critical Magnetic Field ◽  
Spin Orbit ◽  
Zero Temperature ◽  
Interband Pairing ◽  
Two Parameters ◽  
Spin Orbit Interactions ◽  
Parameter Values ◽  
Thin Superconducting Films

The effect of spin-orbit (SO) interaction on the formation of the critical states in thin superconducting films in magnetic field oriented along the film is investigated. Hereby, the case of interband pairing is considered. It was found that eight branches exist in the plane of two parameters [Formula: see text] determined by the value of magnetic field and SO interaction. Six modes leads to inhomogeneous states with different values of the impulse [Formula: see text]. Each state is doubly degenerate over direction of impulse [Formula: see text]. The parameter values at critical point are found for all eight branches in explicit form for zero temperature. The optimal two branches are estimated, corresponding to largest critical magnetic field value for given SO interaction.

scholarly journals DEM Investigation of the Influence of Particulate Properties and Operating Conditions on the Mixing Process in Rotary Drums: Part 1—Determination of the DEM Parameters and Calibration Process

Processes ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 222
Author(s):  
Jakub Hlosta ◽  
Lucie Jezerská ◽  
Jiří Rozbroj ◽  
David Žurovec ◽  
Jan Nečas ◽  
...  
Keyword(s):  
Input Parameter ◽  
Calibration Procedure ◽  
Operating Conditions ◽  
Angle Of Repose ◽  
Shape Accuracy ◽  
Calibration Experiment ◽  
Formation Method ◽  
Method Of Evaluation ◽  
Parameter Values

This paper’s goal was to select methods and a calibration procedure which would lead to the determination of relevant parameters of a discrete element method (DEM) and virtual material creation. Seven particulates were selected with respect to their shape (spherical and non-spherical), size and density. The first calibration experiment involved “packing test” to determine the shape accuracy and bulk density of virtual packed particulates. The series of simulations were compared with real experiments, and the size, shape and density of virtual particles were optimized. Using three apparatuses, the input parameter values were experimentally determined for a contact model that defines the behavior of particulates in DEM simulations. The research part of the paper examines the influence of factors such as particle number; pile formation method; and the method of evaluation of the angle of repose on the process of the calibration of virtual material. The most reproducible results were achieved by the “pilling” method and by the rotating drum—both evaluated by the geometric method. However, it is always advisable to make an overall visual comparison of the slope shape between the calibration simulation and the experimental curves. The bowl’s diameter to particle size ratio should be greater than 25, and the calibration experiment should contain approximately 4000 particles to ensure representative results during angle of repose calibration experiment.

Investigation of Simulation Parameters for Cross Wedge Rolling Titanium and Bainitic Grade Steel

2015 ◽  
Vol 736 ◽  
pp. 165-170 ◽  
Author(s):  
Thoms Blohm ◽  
Malte Stonis ◽  
B.A. Behrens
Keyword(s):  
Process Parameters ◽  
Rolling Process ◽  
Cross Wedge Rolling ◽  
Suitable Parameter ◽  
Simulation Parameters ◽  
Parameter Values ◽  
Grade Steel

In this paper the comparison of simulations of cross wedge rolling processes with real trials using flat cross wedge tools is presented. The investigated materials are titanium and bainitic grade steel. First simulations were used to find the suitable parameter combinations for the investigated materials. Afterwards tools were manufactured with these parameters and additionally with some variations to investigate a field of parameters around this range of parameter values. The purpose of these tests is to find geometrical and process parameters with which a stable cross wedge rolling process for bainitic grade steel and titanium is possible.

How Many Bloods will a ‘HIVCHEK’ Check? Multiple Tests for HIV Antibody for a Single Screening Kit

1992 ◽  
Vol 22 (4) ◽  
pp. 151-154 ◽  
Author(s):  
G J Wannan ◽  
M J Cranefield ◽  
W A M Cutting ◽  
P R Fischer ◽  
F D Hargreaves ◽  
...  
Keyword(s):  
Blood Donors ◽  
Screening Tests ◽  
Serum Samples ◽  
Hiv Seroprevalence ◽  
Multiple Tests ◽  
Test Kit ◽  
Highly Sensitive ◽  
Multiple Sample ◽  
Sample Method ◽  
Hiv 1

Detection of HIV infection in blood donors or populations is usually by testing sera for antibodies to HIV-1 and HIV-2. Screening tests are now highly sensitive and specific, but still expensive and scarce in Africa. We tested the commercially available kits ‘HIVCHEK 1 + 2′ in two field laboratories, on specimens from blood donors and antenatal women in rural Zaire. We describe a method of using one test kit for up to five serum samples, saving money and time. In 491 antenatal mothers in Eastern Zaire, among whom the HIV seroprevalence was 3.3%, we compared ‘HIVCHEK’ results with results obtained by ELISA and Western blot. The ‘HIVCHEK’ multiple-sample method had a sensitivity of 82% and a specificity of 99.6%. In an area with an HIV seroprevalence of <4%, using ‘HIVCHEK’ by the multiple sample method would lead to a saving of about £2400 for every 1000 individuals tested.

Adaptive Iterative Learning Control for Robot Manipulators with Initial Resetting Errors

2011 ◽  
Vol 130-134 ◽  
pp. 265-269 ◽  
Author(s):  
Jian Ming Wei ◽  
Yun An Hu
Keyword(s):  
Iterative Learning Control ◽  
Robot Manipulators ◽  
Error Function ◽  
Tracking Error ◽  
Learning Control ◽  
Iterative Learning ◽  
Unknown Parameters ◽  
Adaptive Iterative Learning Control ◽  
Suitable Parameter ◽  
Parameter Values

In this paper, an adaptive iterative learning control is presented for robot manipulators with unknown parameters, performing repetitive tasks. In order to overcome the initial resetting errors, an auxiliary tracking error function is introduced. The adaptive algorithm is derived along the iteration axis to search for suitable parameter values. The technical analysis shows convergence of the tracking errors. Finally, simulation results are provided to illustrate the effectiveness of the proposed controller.

TURBULENT DIFFUSION OF TEST PARTICLES IN STRONGLY MAGNETIZED PLASMAS

1991 ◽  
Vol 05 (08) ◽  
pp. 1243-1262 ◽  
Author(s):  
MAURIZIO OTTAVIANI ◽  
MARCO PETTINI
Keyword(s):  
Electric Field ◽  
Equations Of Motion ◽  
Charged Particles ◽  
Mean Square Displacement ◽  
Wave Model ◽  
Particle Dynamics ◽  
Suitable Parameter ◽  
Test Particles ◽  
The Mean ◽  
Parameter Values

The motion of charged particles is described in the presence of a strong magnetic field and of an electric field made of three spatial Fourier modes whose amplitudes vary in time. The dynamics of the wave amplitudes is governed by a model of three interacting drift waves. For suitable parameter values of the three-wave model, chaotic solutions are found so that the Eulerian electric field is made of three turbulent modes. The E × B motion is described for charged particles in the guiding center approximation, which brings to nonlinear Hamiltonian equations of motion. The Hamiltonian (that coincides with the electric potential) is explicitly time-dependent through the temporal variation of the mode-amplitudes of the electric field, this fact is at the origin of the intrinsic chaoticity of particle dynamics (lagrangian chaos). Diffusive behaviour of particle trajectories is due to their intrinsic chaoticity and thus it is of non-collisional origin. Some results are reported concerning the particle dynamics when the Eulerian electric field is either quasi-periodically or chaotically varying in time. In particular, one finds different diffusion laws in the two cases (anomalous and classical respectively). The scaling behaviour of the diffusion coefficients (when the mean square displacement grows linearly in time) is reported. A simple stochastic model is also used to account for some of the observed features of particle diffusion.

Two-step validation process of particle mixing in a centrifugal mixer with vertical axis

2016 ◽  
Vol 232 (1) ◽  
pp. 29-37
Author(s):  
Matej Zadravec ◽  
Blaž Orešnik ◽  
Matjaž Hriberšek ◽  
Jure Marn
Keyword(s):  
Numerical Simulation ◽  
Friction Coefficient ◽  
Numerical Simulations ◽  
Static Friction ◽  
Vertical Axis ◽  
Rolling Friction ◽  
Angle Of Repose ◽  
Discrete Elements ◽  
Power Characteristics ◽  
Centrifugal Mixer

Two-step approach of validation is proposed to validate a numerical model, capable of accurate prediction of mixing power characteristics of a centrifugal mixer with vertical axis. Two sets of experiments and two sets of numerical simulations are presented—the first set to determine physical characteristics of the particles comparing the numerical simulations results with experimental data, and the second set to validate predicted behavior of anchor type vertical axis impeller for mixing of same particles. Zeolite particles were used for actual calculations. After determining shear modulus, coefficient of interaction, static friction coefficient, and rolling friction coefficient through optimization process based on numerical simulations with subject function of diameter and angle of repose derived from experiment, using these values in numerical simulation of impeller mixer mixing zeolite particles led to results, which were in good agreement with results of the second set of experiments. The obtained zeolite material parameter values can therefore serve as a solid basis for discrete elements method based numerical simulation of zeolite granular materials.

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