Empirical assessment of the critical time increment in explicit particulate discrete element method simulations

This contribution considers the critical time increment (〖∆t〗_crit) to achieve stable simulations using particulate discrete element method (DEM) codes that adopt a Verlet-type time integration scheme. The 〖∆t〗_crit is determined by considering the maximum vibration frequency of the system. Based on a series of parametric studies, 〖∆t〗_crit is shown to depend on the particle mass (m), the maximum contact stiffness (Kmax), and the maximum particle coordination number (CN,max). Empirical expressions relating 〖∆t〗_crit to m, Kmax, and CN,max are presented; while strictly only valid within the range of simulation scenarios considered here, these can inform DEM analysts selecting appropriate 〖∆t〗_crit values

Empirical assessment of the critical time increment in explicit particulate discrete element method simulations

This contribution considers the critical time increment (〖∆t〗_crit) to achieve stable simulations using particulate discrete element method (DEM) codes that adopt a Verlet-type time integration scheme. The 〖∆t〗_crit is determined by considering the maximum vibration frequency of the system. Based on a series of parametric studies, 〖∆t〗_crit is shown to depend on the particle mass (m), the maximum contact stiffness (Kmax), and the maximum particle coordination number (CN,max). Empirical expressions relating 〖∆t〗_crit to m, Kmax, and CN,max are presented; while strictly only valid within the range of simulation scenarios considered here, these can inform DEM analysts selecting appropriate 〖∆t〗_crit values

Numerical modelling of rough particle contacts subject to normal and tangential loading

Our understanding of the mechanics of contact behaviour for interacting particles has been developed mostly assumingthat surfaces are smooth. However,real particlesof interest inengineering science are generally rough. While recent studies have considered the influence of roughness on the normal force-displacement relationship, surface roughness was quantified using only a single scalar measure, disregardingthe topology of the surface. There are some conflicting arguments concerning the effect of roughness on the tangential or shear force-displacement relationship. In this study,optical interferometry data are used to generate the surface topology for input into a 3D finite element model. This model is used to investigate the sensitivity of the normal force-displacement response to thesurfacetopology by considering differentsurfaces with similar overall roughness values. The effect of surface roughness on the tangential force-displacement relationshipand the influence of loading history are also explored. The results indicate that quantifying roughness using a single value, such as the root mean square height of roughness, Sq, is insufficient to predict the effect of roughness upon stiffness. It is also shown that in the absenceof interlocking,rough particle surfaces exhibit a lower frictional resistance in comparison with equivalent smooth surfaces

Aspectos do cultivo da mandioca em Mato Grosso do Sul.

bitstream/item/38819/1/LV20021.pdfPalestras apresentadas nos I e II Seminários sobre a Cultura da Mandioca em Mato Grosso do Sul

Mandioca de mesa: aspectos de produção, comercialização e consumo em Dourados, MS.

Mandioca de mesa em Mato Grosso do Sul; Mandioca de mesa em Dourados, MS; Aspectos tecnológicos da produção; Caracterização dos agentes de produção e comercialização; Caracterização do consumo.bitstream/item/65722/1/DOC36-mand.pd

Nutrição nitrogenada na cultura da soja em Mato Grosso do Sul: reinoculação x adubação nitrogenada.

bitstream/item/24733/1/COT200266.pdfDocumento on-line

Implantação de desenvolvimento da produção integrada de mandioca em cinco regiões produtoras do Brasil.

Publicado também na: RAT: Revista Raízes e Amidos Tropicais, v. 3, 2007. (SEP 040)

IAC 576 - cultivar de mandioca de mesa recomendada para Mato Grosso do Sul.

bitstream/item/24714/1/COT200380.pdfDocumento on-line

Influence of synaptic depression on memory storage capacity

Synaptic efficacy between neurons is known to change within a short time scale dynamically. Neurophysiological experiments show that high-frequency presynaptic inputs decrease synaptic efficacy between neurons. This phenomenon is called synaptic depression, a short term synaptic plasticity. Many researchers have investigated how the synaptic depression affects the memory storage capacity. However, the noise has not been taken into consideration in their analysis. By introducing "temperature", which controls the level of the noise, into an update rule of neurons, we investigate the effects of synaptic depression on the memory storage capacity in the presence of the noise. We analytically compute the storage capacity by using a statistical mechanics technique called Self Consistent Signal to Noise Analysis (SCSNA). We find that the synaptic depression decreases the storage capacity in the case of finite temperature in contrast to the case of the low temperature limit, where the storage capacity does not change