Discrete elements

In die simulation model, die FCC system was subdivided into discrete elements and suitable subsystems. This model provided all die process parameters such as pressures, flowrates, and temperatures. Figure 6-44 shows die corresponding block diagram. (The model for die expander, piping systems, and vessels is based on a gas turbine model described by GHH Borsig in a paper by W. Blotenberg.)... 

Lewis RW, Gethin DT, Yang XS, Rowe RC. A combined finite-discrete element method for simulating pharmaceutical powder tableting. Int J Num Meth Eng 2005 62 853-69. 

So far, some researchers have analyzed particle fluidization behaviors in a RFB, however, they have not well studied yet, since particle fluidization behaviors are very complicated. In this study, fundamental particle fluidization behaviors of Geldart s group B particle in a RFB were numerically analyzed by using a Discrete Element Method (DEM)- Computational Fluid Dynamics (CFD) coupling model [3]. First of all, visualization of particle fluidization behaviors in a RFB was conducted. Relationship between bed pressure drop and gas velocity was also investigated by the numerical simulation. In addition, fluctuations of bed pressure drop and particle mixing behaviors of radial direction were numerically analyzed. 

In neither the mechanical nor the electronic approaches is the beam perfectly sharp. This is inevitable since the aperture of the system is finite in extent. In the case of the electronic array, this problem is compounded by the fact that the array has discrete elements, rather than a continuum. However, in the latter case it is controllable. As a result of this imperfection, again the scene is blurred in this case... 

A simpler version of the discrete element model is the so-called trajectory model. In the trajectory approach, droplet field is modeled as a series of trajectories that emanate from the atomizer or a starting point. The coupling effects are included by summing the heat release to and the drag force on the gas phase. This approach can be used for steady dilute flows. 

Most pharmaceutical firms have pipelines fofaling less than 1000 developmental compounds, and often no more than 40. Handling these smaller sample sizes requires an approach, which is capable of affaching individual characteristics to xmique, discrete elements. Such models are called "agent-based " they establish a simulation environment in which individual agents represent actual NCEs in the pipeline, complete with unique characteristics that can be compound-specific. In addihon, the small numbers of items tracked dictate that they must be "discrete event " model inputs must have a range of... 

Classical ( Pavlovian ) conditioning is a process whereby a subject learns the associative relationships between discrete elemental or configural stimuli, with... 

Fibrous protein sequences are often characterized by the presence of simple repetitive motifs. Some are exact in length and/or sequence, but others are only approximate and display considerable variation. Some motifs contain residues that are absolutely conserved in some positions, whereas in others it is only the sequence character that is maintained over the repeat length. In many fibrous proteins the repeats occur contiguously, whereas in others they are found widely separated in the sequence. The varieties of sequence repeat that have been observed are typed and catalogued here by Parry (Chapter 2). Each motif forms a discrete element of structure in many instances, these are arranged helically with respect to one another. In many cases an elongate structure is formed, and this can lead naturally to molecular aggregation and the formation of functional filaments. 

P.W. Cleary, Predicting charge motion, power draw, segregation and wear in ball mills using discrete element methods, Miner. Eng. 11 (1998) 1061-1080. 

Three types of theoretical approaches can be used for modeling the gas-particles flows in the pneumatic dryers, namely Two-Fluid Theory [1], Eulerian-Granular [2] and the Discrete Element Method [3]. Traditionally the Two-Fluid Theory was used to model dilute phase flow. In this theory, the solid phase is being considering as a pseudo-fluid. It is assumed that both phases are occupying every point of the computational domain with its own volume fraction. Thus, macroscopic balance equations of mass, momentum and energy for both the gas and the solid... 

Based on the pilot scale measurements mathematical modeling was started in order to describe the processes. Discrete element method (DEM) was used to model the mixing. This was originated from a simple mechanical model to formulate... 

Measurements were carried out in order to correct the existing discrete element methods that describe mixing effect of granules in a bulk. Different densities and friction coefficients of particles were studied to find correlations between the parameters and the mixing characteristics. There was found no effect of these parameters on mixing. Therefore, the DEM modeling work in this case has to be reevaluated. 

Todorov, I.T., and W. Smith. 2004. DL POLY 3 The CCP5 national UK code formolecular-dynamics simulations. One contribution of 12 to a theme Discrete element modelling Methods and applications in the environmental sciences. Phil. Trans. R. Soc. Lond. A 362 1835-1852. 

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