A theoretical model is suggested which describes the yield stress dependence on grain size in fine-grained materials, based upon competition between conventional dislocation slip, grain boundary diffusional creep (Coble creep) and triple junction diffusional creep. In the framework of the model, the contribution of diffusional creep mechanisms to plastic deformation increases with reduction of ...

there are different methods used for threshing of grain crops. usual threshers operate based on the impact force (in threshing unit) that may damage the grains. in another method named axial-flow, grain damage is less so these types of the harvesting machines are being used more than before. in this study one of the common rice threshers (model t30) locally made in ashtad company was modified t...

A two-dimensional diffusion based model is developed to describe transformation of austenite into ferrite and pearlite under continuous cooling conditions. The nucleation of ferrite is assumed to occur over grain boundaries and the nucleation of pearlite is assumed to be taking place all over the grain and at growing ferrite–austenite interfaces, when the composition and temperature conditions ...

Abstract The aim of this research is to present a simulation model for reducing economic damages of mechanized wheat harvesting in the weather conditions of Khuzestan province and similar areas. The simulated model is composed of three sub-models, for determining of the appropriate working hours, grain losses, and economic sub-model. In order to determine the appropriate working hours, a mathem...

A two dimensional cellular automata model has been developed to simulate and to study grain growth behavior during solidification and recrystallization processes, including predicting mechanical properties of metallic materials or investigating mechanical defects. Using the algorithm implemented, grain growth in model materials (nickel-based and titanium alloys) has been calculated in different...

Our collaboration has resulted in a series of three papers on a new model for grain boundarydiffusion creep in partially molten rocks. The broad aim is to better understand the physical processes controlling the interactions of deformation, melt distribution and melt migration. Towards this aim, we saw the need for a 3-D, grain-scale model for viscosity in the presence of melt. The constitutive...

At microscale, the large ratio between mean grain size of the material and specimen dimension cause an increasing influence of single grain forming behaviour on the overall forming process. Thus the forming behaviour of these parts can no longer be regarded as to be homogeneous. This leads to a change in the material behaviour resulting in a large scatter of forming results, e.g. varying cup he...

the grain aphid, sitobion avenae (hemiptera: aphididae) is one of the injuriously important pests of wheat and praon volucre (hymenoptera: braconidae) is one of its major parasitoids in iran. in this research, thermal requirements of the grain aphid and its parasitoid were evaluated at six constant temperatures (10, 15, 20, 25, 27.5 and 30 °c), 60 ± 5 % relative humidity and a photoperiodicity ...