Application of DEM to evaluate and compare process parameters for a particle failure under different loading conditions

The paper presents an application of Discrete Element Modelling (DEM) in understanding the micro-process parameters of a particle failure under different loading conditions. A composite particle has been modelled using many primary particles to represent a quasi-homogeneous particle. Some of the examples of quasi-homogeneous particles are constituents of tablets, pellets, granules and concrete. These particles can behave differently under identical loading conditions even though they consist of same primary particles and proportions. This is a typical behaviour of such particles which is governed by the imperfections present in the particles. A DEM has been used to model the composite particle consisting of bi-modal distribution (smaller particles—matrices and larger particles—aggregates) of primary particles. The particle has been loaded under single plate compression, double plate compression and normal impact on different types of target. The single plate compression and normal impact experiments have also been performed. Process parameters like, fracture pattern, particle size distribution, liberation degree and new surface generation have been evaluated and compared. The results are applicable in understanding the particle failure under different processing operations like, transportation, handling and comminution. The results are also useful in selecting the better loading method for liberating aggregates from cheaper matrices for recycling.     

Hierarchical classifier: Based on neural networks searching tree with iterative traversal and stop criterion

The paper offers an algorithm that extends the binary tree search algorithm so that it can deal with distorted input vectors. Perceptrons are the tree nodes. The algorithm features an iterative solution search and stopping criterion.     

The Effects of Cryogenic Storage on Human Dental Pulp Stem Cells

Dental pulp stem cells (DPSCs) are a type of easily accessible adult mesenchymal stem cell. Due to their ease of access, DPSCs show great promise in regenerative medicine. However, the tooth extractions from which DPSCs can be obtained are usually performed at a period of life when donors would have no therapeutic need of them. For this reason, it is imperative that successful stem cell storage techniques are employed so that these cells remain viable for future use. Any such techniques must result in high post-thaw stem cell recovery without compromising stemness, proliferation, or multipotency. Uncontrolled-rate freezing is not a technically or financially demanding technique compared to expensive and laborious controlled-rate freezing techniques. This study was aimed at observing the effect of uncontrolled-rate freezing on DPSCs stored for 6 and 12 months. Dimethyl sulfoxide at a concentration of 10% was used as a cryoprotective agent. Various features such as shape, proliferation capacity, phenotype, and multipotency were studied after DPSC thawing. The DPSCs did not compromise their stemness, viability, proliferation, or differentiating capabilities, even after one year of cryopreservation at −80 °C. After thawing, they retained their stemness markers and low-level expression of hematopoietic markers. We observed a size reduction in recovery DPSCs after one year of storage. This observation indicates that DPSCs can be successfully used in potential clinical applications, even after a year of uncontrolled cryopreservation.     

Confluence and termination of fuzzy relations

Confluence and termination are essential properties connected to the idea of rewriting and substituting which appear in abstract rewriting systems. The aim of the present paper is to investigate confluence, termination, and related properties from the point of view of fuzzy logic leaving the ordinary notions a particular case when the underlying structure of truth degrees is two-valued Boolean algebra. The main motivation of this study is the fact that in several natural situations, the notion of substitutability is inherently fuzzy rather than crisp.     

Feeding ecology of emerald shiners and rainbow smelt in central Lake Erie

To better understand the feeding ecology of two important Laurentian Great Lakes prey species, rainbow smelt Osmerus mordax and emerald shiners Notropis atherinoides, we quantified the diet composition, selectivity, daily ration, and diet overlap of both species in offshore central Lake Erie during May through October 2005, which spanned a period of severe hypolimnetic hypoxia (< 2 mg O₂/L). Rainbow smelt fed upon a variety of prey taxa, including zooplankton, chironomid pupae and larvae, and fish, whereas emerald shiners primarily consumed cladocerans, if available. In turn, diet overlap between rainbow smelt and emerald shiners was low except during September when hypolimnetic hypoxia reduced rainbow smelt access to benthic prey. Rainbow smelt most frequently selected chironomid pupae, while emerald shiners generally selected pupae or large predatory cladocerans (Leptodora or Bythotrephes). Daily ration and individual consumption by rainbow smelt were 54–68% less during hypoxia than at the same site during stratified pre-hypoxic or mixed post-hypoxic conditions. Although emerald shiner daily ration and individual consumption decreased between pre-hypoxic and hypoxic periods, it continued to decrease during the post-hypoxic period, suggesting that reduced consumption may not have been linked to hypoxic conditions. Ultimately, our findings suggest that emerald shiners are as important regulator of zooplankton abundance in the Great Lakes as rainbow smelt, given their potentially high mass-specific consumption rates, selectivity and diet patterns, and current high abundance.     

Validation of a dynamic model for wood pellet boilers and stoves

Optimising systems with wood pellet boilers or stoves using simulations requires realistic computer models. The objective of this work was to develop and verify a mathematical model for wood pellet boilers and stoves for use in system simulations with the dynamic simulation programme TRNSYS, calculating both the energy balance and the CO-emissions (carbon monoxide emissions). Laboratory measurements have been carried out and a mathematical two-node model was developed and implemented as a TRNSYS component. Parameters were identified and the model has been compared with measurements. The model shows in general good agreement with measured data, however there are details that could be improved. This involves improved modelling of the dynamic response for boilers with large water volumes and improved modelling of the air factor and the CO-emissions, especially during start and stop conditions. Further improved methodology and accuracy for measuring and parameter identification is recommended.