Parameter Optimization for a Potato Rod-type Conveyor Grading Device Based on the Discrete Element Method

Existing field potato grading devices are complex in structure and large in volume, designing a rod-type conveyor grading device. Relying on field measurement, size and field distribution laws of mature potatoes are obtained and their field distribution is modelled. Moreover, the conveyor grading device model is established using the discrete element method (EDEM). The single-factor test and multi-factor test adopting one evaluation index (grading accuracy) and four test factors (conveyor chain elevation angle, conveyor chain speed, rod clearance, and potato feed rate) were conducted. Finally, the effects of various test factors on the evaluation index are analyzed and test factors are optimized. According to the results of this study, the rod-type conveyor grading device had a grading accuracy of 93.32%. The relative error between experimental validation and simulation results was less than 8%, suggesting that the regressive mathematical model proposed in this paper and the optimization results obtained were reasonable

Proceedings of the European Conference on Agricultural Engineering AgEng2021

This proceedings book results from the AgEng2021 Agricultural Engineering Conference under auspices of the European Society of Agricultural Engineers, held in an online format based on the University of Évora, Portugal, from 4 to 8 July 2021. This book contains the full papers of a selection of abstracts that were the base for the oral presentations and posters presented at the conference. Presentations were distributed in eleven thematic areas: Artificial Intelligence, data processing and management; Automation, robotics and sensor technology; Circular Economy; Education and Rural development; Energy and bioenergy; Integrated and sustainable Farming systems; New application technologies and mechanisation; Post-harvest technologies; Smart farming / Precision agriculture; Soil, land and water engineering; Sustainable production in Farm buildings

Discrete element modelling of the dynamic behaviour of non-spherical particulate materials

PhD ThesisA numerical model based on the discrete element (DE) method, for modelling the flow of irregularly shaped, smooth-surfaced particles in a 3-D system is presented. An existing DE program for modelling the contact between spherical particles in periodic space (without real walls or boundaries) was modified to model non-spherical particles in a system with containing walls. The new model was validated against analytical calculations of single particle movements and also experimentally against data from physical experiments using synthetic non-spherical particles at both a particle and bulk scale. It was then used to study the effect of particle shape on the flow behaviour of assemblies of particles with various aspect ratios discharging from a flat-bottomed hopper. The particles were modelled using the Multi-Sphere Method (MSM) which is based on the CSG (Constructive Solid Geometry) technique for construction of complex solids by combining primitive shapes. In this method particle geometry is approximated using overlapping spheres of arbitrary diameter which are fixed in position relative to each other. The contact mechanics and contact detection method are the same as those used for spheres, except that translation and rotation of element spheres are calculated with respect to the motion of the whole particle....Numerical simulations of packing and flow of particles from a flat-bottomed hopper with a range of aspect ratios were performed to investigate the effect of particle shape on packing and flow behaviour of a particulate assembly. It was found that the particle shape influenced both bed structure and flow characteristics such as flow pattern, shear band strength and the occurrence of bridging. The flow of the bed of spherical particles was smoother than the flow of beds of elongated particles in which flow was fluctuating and there was more resistance to shear.Ministry of Culture and Higher Education of IRAN: University of Mashhad

The Second Conference on Lunar Bases and Space Activities of the 21st Century, volume 2

These 92 papers comprise a peer-reviewed selection of presentations by authors from NASA, the Lunar and Planetary Institute (LPI), industry, and academia at the Second Conference on Lunar Bases and Space Activities of the 21st Century. These papers go into more technical depth than did those published from the first NASA-sponsored symposium on the topic, held in 1984. Session topics included the following: (1) design and operation of transportation systems to, in orbit around, and on the Moon; (2) lunar base site selection; (3) design, architecture, construction, and operation of lunar bases and human habitats; (4) lunar-based scientific research and experimentation in astronomy, exobiology, and lunar geology; (5) recovery and use of lunar resources; (6) environmental and human factors of and life support technology for human presence on the Moon; and (7) program management of human exploration of the Moon and space

Using similitude theory and discrete element modeling to understand the effects of digging parameters on excavation performance for rubber tire loaders

The large sizes of mining equipment pose challenges for analysis using experiments or simulation. While scaled physical and simulation models can address this challenge, no previous work has explored how similitude theory and modeling can provide valid analysis of large equipment such as rubber tire loaders. The objective of this research was to apply similitude theory and discrete element modeling (DEM) to study the effect of different digging parameters on the penetration and the draft on the buckets of rubber tire loaders. The work sought to (1) test the hypothesis that the geometry of a rubber tire loader bucket and operating conditions significantly affects the resistive force (draft) and penetration; (2) test the hypothesis that different geometry orientations and operating conditions of a rubber tire loader bucket significantly affects draft and penetration; (3) apply DEM to scale models of rubber tire loader buckets to understand the effect of bucket geometry, orientations, and operating conditions on draft and penetration; and (4) evaluate the effectiveness of using discrete element models and similitude theory to predict draft and penetration. The results show that geometry, muckpile particle sizes, height above the floor, rake angle, speed, and motor power output are correlated to penetration and draft. This work has demonstrated that we can build valid DEM models for predicting at a larger scale. The chamfer angle of semi-spade bucket cutting blades significantly affects the draft on the buckets and 30° chamfer cut angle performs the best with the lowest peak resistive forces and energy consumption. The work finds that the forces observed during the rotation phase of the simulation are lower than the observed forces during penetration --Abstract, page iii

The effect of microwave heating on ore sorting

Today the Mining industry is being challenged to develop methodologies and technology to process the lower grade and mineralogically complex ore types using ore sorting. The potential of microwave driven selective heating as an excitation tool to underpin sorting is possibly not well known in the mining and mineral industries due to very few applications and lack of awareness of the potential users. This thesis investigates the conditions under which this process is technically effective and can be utilised. A detailed investigation was conducted to understand the reasons for selective heating of specific mineral phases and how infrared sensing can be used as an identification technique to discriminate certain particles from others. This thesis also quantifies the impact of other important factors on the sorting process including; particle shape and size, mineral composition and most importantly the textures of the mineral bearing particles which have a tendency to heat quickly when exposed to microwave energy. An extensive assembly of analytical techniques such as optical microscopy, high-resolution X-ray computed tomography and XL Scanning Electron Microscopy (used by the Mineral Liberation Analyser) were utilised to obtain a mineralogical characterisation of the tested ores. The choice of microwave applicators enabled heating to be carried out in multimode and single mode types of cavity. By engineering synthetic samples a more comprehensive investigation was carried out which enabled some focusing questions from the thesis hypothesis to be addressed. The synthetic samples were used to experimentally validate an adopted theoretical approach of investigating the influence of mineral texture upon selective heating. The supplied ore from the Bingham Canyon Mine, USA (operated by Rio Tinto’s Kennecott Utah Copper Corporation) was experimentally tested in two steps of investigations. The first step involved the approach of an “ideal”, theoretical sorter for which rock particles had to be destroyed (necessary to perform assaying analysis). The temperature threshold for economically justifiable sorting was determined from a temperature difference and assayed metal content of heated particles. In the second step, samples were analysed by heating them in two applicators and the temperature threshold was determined as a function of mineral texture which caused selective heating as in contrast to assayed metal content. The results showed from the exposure of synthetic particles (with designed textures of microwave more responsive minerals) that it is advantageous to use both multimode and single mode cavities for better understanding of microwave heating of the ore. It was also shown that the texture of microwave responsive minerals has a significant effect on the formation of the temperature profiles which are used to evaluate selectivity and potential for the separation as opposed to only mineral composition of the ore particles. It was demonstrated that the types of ores studied in this work, will respond to microwave selective heating to the extent that infrared detection can be applied to perform selection between cold and hot particles defined by a set threshold

Spinoff, 1990

This publication is intended to foster the aim of the NASA Technology Utilization Program by heightening awareness of the NASA technology available for transfer and its potential for benefits realized by secondary applications. Spinoff 1990 is organized in three main sections. Section 1 outlines NASA's mainline effort, the major programs that generate new technology and therefore replenish and expand the bank of knowledge available for transfer. Section 2 contains a representative sampling of spinoff products that resulted from secondary application of technology originally developed to meet mainline goals. Section 3 describes the various mechanisms NASA employs to stimulate technology transfer and lists, in an appendix, contact sources for further information about the Technology Utilization Program