Previous soil-disc force prediction models have considered spherical and concave blades, as used on disc ploughs and harrows, with many simplifying assumptions. This study proposes an approach applying the fundamental...Previous soil-disc force prediction models have considered spherical and concave blades, as used on disc ploughs and harrows, with many simplifying assumptions. This study proposes an approach applying the fundamental equation of earth moving mechanics for calculating the soil passive reaction acting on a rotating fiat disc blade as used on a zero-till single disc seeder. The study considers the effects of disc variable depth of cut, sweep and tilt angles, free rotation and a scrubbing reaction at the beveled edge. This paper outlines the modeling approach and prediction results for a fixed circular blade operating at 90° sweep angle over a range of speeds and at two tilt angles. To account for the varying depth across the circular disc shape width, elemental wide blade force reactions acting on wide blade segments of elemental width were integrated across the disc working width. By including inertia forces due to speed as well as additional bulldozing forces due to the loose soil accumulation in front of the blade the draught and upward vertical forces acting on the vertical disc blade were predicted with a deviation of 6%-19% and 1.5%-14% from measured data, respectively. The model was able to predict the effect of increasing the tilt angle from 0° to 20° on reducing both draught and upward vertical forces. Further development and validation of the model will be described in subsequent papers, reflecting a step by step approach of increasing complexity to model a disc blade as used on a zero-till single disc seeding system.展开更多
The rice-wheat rotation system plays a significant role in Asian agriculture.The introduction of strip-tillage into the rice-wheat system for wheat planting offers a way to use conservation tillage practices to improv...The rice-wheat rotation system plays a significant role in Asian agriculture.The introduction of strip-tillage into the rice-wheat system for wheat planting offers a way to use conservation tillage practices to improve the seedbed quality,retain residue between rows and reduce energy input.A field experiment was conducted using an in-situ test rig.Three types of blade(bent C,straight and hoe)were evaluated in four tool configurations at four rotary speeds(180 r/min,280 r/min,380 r/min and 510 r/min)in a paddy soil.Furrow shape parameters,tillage-induced soil structures and energy consumption were assessed.Results showed that the straight blade configuration failed to create a continuous furrow at either 180 r/min or 510 r/min.The bent C blade configuration produced a uniform furrow profile but its furrow backfill was poor and unsuitable for seeding.The hoe blade configuration cut a continuous furrow and better tillage-induced soil structure,but it produced a much wider and non-uniform furrow shape.The mixed blade configuration(central hoe blades with two straight blades aside)provided a uniform furrow with good backfill and fine tilth by utilizing both the cutting effect of straight blades on the furrow boundaries and tensile fracturing of the furrow soil by the hoe blades.The torque of the mixed blade configuration was comparable with the bent C blade but was less than the hoe blades.Hence,a mixed blade configuration was recommended for rotary strip-tillage seeding using in rice-wheat system.展开更多
The Australian almond industry desires to improve storage of harvested almonds awaiting processing.The present work quantified some storage-related physical properties of almonds.The sample used in the study was Nonpa...The Australian almond industry desires to improve storage of harvested almonds awaiting processing.The present work quantified some storage-related physical properties of almonds.The sample used in the study was Nonpareil almonds with a kernel moisture content of 4.5% d.b.The mass composition of the sample was 55% hull,32% kernel and 13% shell.Tests showed that the bulk stored in-shell almonds had only 41% of the volume of in-hull almonds and 45% of the mass.Thus removing hulls before storage would result in saving both storage and subsequent transportation costs.Tests simulating various storage heights of almonds showed that a 10 m storage height of almonds increased the bulk density of in-hull almonds from 320 to 355 kg/m^(3),of in-shell almonds(hull removed)from 356 to 378 kg/m3,and kernels(hull and shell removed)from 604 to 649 kg/m^(3).A 10 m storage height of almonds reduced the porosity of in-hull almonds from 67% to 64%,of in-shell almonds from 58% to 55%,and of the kernel from 48% to 44%.Observation showed that the change in bulk density and porosity occurred in an exponential manner with fitted curves that provided R2 between 0.97 and 0.99.展开更多
文摘Previous soil-disc force prediction models have considered spherical and concave blades, as used on disc ploughs and harrows, with many simplifying assumptions. This study proposes an approach applying the fundamental equation of earth moving mechanics for calculating the soil passive reaction acting on a rotating fiat disc blade as used on a zero-till single disc seeder. The study considers the effects of disc variable depth of cut, sweep and tilt angles, free rotation and a scrubbing reaction at the beveled edge. This paper outlines the modeling approach and prediction results for a fixed circular blade operating at 90° sweep angle over a range of speeds and at two tilt angles. To account for the varying depth across the circular disc shape width, elemental wide blade force reactions acting on wide blade segments of elemental width were integrated across the disc working width. By including inertia forces due to speed as well as additional bulldozing forces due to the loose soil accumulation in front of the blade the draught and upward vertical forces acting on the vertical disc blade were predicted with a deviation of 6%-19% and 1.5%-14% from measured data, respectively. The model was able to predict the effect of increasing the tilt angle from 0° to 20° on reducing both draught and upward vertical forces. Further development and validation of the model will be described in subsequent papers, reflecting a step by step approach of increasing complexity to model a disc blade as used on a zero-till single disc seeding system.
基金supported by the State Key Program of China(2016 YFD 0300900)Jiangsu Agri.Mech.Fund(201-051028).
文摘The rice-wheat rotation system plays a significant role in Asian agriculture.The introduction of strip-tillage into the rice-wheat system for wheat planting offers a way to use conservation tillage practices to improve the seedbed quality,retain residue between rows and reduce energy input.A field experiment was conducted using an in-situ test rig.Three types of blade(bent C,straight and hoe)were evaluated in four tool configurations at four rotary speeds(180 r/min,280 r/min,380 r/min and 510 r/min)in a paddy soil.Furrow shape parameters,tillage-induced soil structures and energy consumption were assessed.Results showed that the straight blade configuration failed to create a continuous furrow at either 180 r/min or 510 r/min.The bent C blade configuration produced a uniform furrow profile but its furrow backfill was poor and unsuitable for seeding.The hoe blade configuration cut a continuous furrow and better tillage-induced soil structure,but it produced a much wider and non-uniform furrow shape.The mixed blade configuration(central hoe blades with two straight blades aside)provided a uniform furrow with good backfill and fine tilth by utilizing both the cutting effect of straight blades on the furrow boundaries and tensile fracturing of the furrow soil by the hoe blades.The torque of the mixed blade configuration was comparable with the bent C blade but was less than the hoe blades.Hence,a mixed blade configuration was recommended for rotary strip-tillage seeding using in rice-wheat system.
基金part of the HAL Project(AL12003)Advanced Processing of Almondsfunded by Horticulture Australia Limited using the almond levy,voluntary contributions from industry and matched funds from the Australian government.
文摘The Australian almond industry desires to improve storage of harvested almonds awaiting processing.The present work quantified some storage-related physical properties of almonds.The sample used in the study was Nonpareil almonds with a kernel moisture content of 4.5% d.b.The mass composition of the sample was 55% hull,32% kernel and 13% shell.Tests showed that the bulk stored in-shell almonds had only 41% of the volume of in-hull almonds and 45% of the mass.Thus removing hulls before storage would result in saving both storage and subsequent transportation costs.Tests simulating various storage heights of almonds showed that a 10 m storage height of almonds increased the bulk density of in-hull almonds from 320 to 355 kg/m^(3),of in-shell almonds(hull removed)from 356 to 378 kg/m3,and kernels(hull and shell removed)from 604 to 649 kg/m^(3).A 10 m storage height of almonds reduced the porosity of in-hull almonds from 67% to 64%,of in-shell almonds from 58% to 55%,and of the kernel from 48% to 44%.Observation showed that the change in bulk density and porosity occurred in an exponential manner with fitted curves that provided R2 between 0.97 and 0.99.
