Performance prediction and optimization for industrial sieves by simulation : a two-tier approach

We present a numerical study of sieving behavior on industrial sieves, composed of several vibrating screens, a process widely used in diverse industries. The modeling approach is twofold: on the one hand, particle flow is modeled in some detail by means of a discrete element model (DEM). This allows studying the influence of various parameters on the behavior of individual particles, particularly transport velocities and collision rates. Computational complexity however forbids the simulation of an entire sieve as a DEM. Instead, the overall sieving behavior is modeled separately by means of a more phenomenological model, the so called thick layer model (TLM), which is based on mass-balance equations, that translate into an ordinary differential equation. The TLM obtains its most crucial input parameters as results of the DEM. Comparison of simulation results with measurements shows, that this combined approach is capable of accurately describing the sieving process at a reasonable computational cost

Death and transfiguration in static staphylococcus epidermidis cultures

The overwhelming majority of bacteria live in slime embedded microbial communities termed biofilms, which are typically adherent to a surface. However, when several Staphylococcus epidermidis strains were cultivated in static liquid cultures, macroscopic aggregates were seen floating within the broth and also sedimented at the test tube bottom. Light- and electron microscopy revealed that early-stage aggregates consisted of bacteria and extracellular matrix, organized in sheetlike structures. Perpendicular under the sheets hung a network of periodically arranged, bacteria-associated strands. During the extended cultivation, the strands of a subpopulation of aggregates developed into cross-connected wall-like structures, in which aligned bacteria formed the walls. The resulting architecture had a compartmentalized appearance. In late-stage cultures, the wall-associated bacteria disintegrated so that, henceforth, the walls were made of the coalescing remnants of lysed bacteria, while the compartment-like organization remained intact. At the same time, the majority of strand containing aggregates with associated culturable bacteria continued to exist. These observations indicate that some strains of Staphylococcus epidermidis are able to build highly sophisticated structures, in which a subpopulation undergoes cell lysis, presumably to provide continued access to nutrients in a nutrient-limited environment, whilst maintaining structural integrity

Bidirectional Interoperability of Product Engineering and Manufacturing Enhancing Mass Customization

Due to the global trend of spreading interconnectedness smart factories evolve and manufacturing entities become cyber-physical systems. This enables mass customization as it allows directing a product through manufacturing individually. However, customer demands can change quickly, and a rapid respond is vital for successful individualization. Therefore, a learning process from every iteration should not only take place in manufacturing but in product engineering as well. Still, there is hardly any interface allowing a bidirectional stream of data up and down the development process. In this paper an approach for realizing bidirectional interoperability between product engineering and manufacturing is developed. The state of the art regarding data exchange and the requirements that data and information systems must join are analysed. Based on the results, this paper elaborates a concept of an information technology architecture enabling bidirectional interoperability. Hence, two theoretical scenarios on the possible deployment of manufacturing information in product engineering are discussed

Late stage structures.

<p>A. SEM picture, 14-day culture, MH strain: the thin compartment walls contain only few bacteria. B. Transmission electron microscopy (TEM) picture, 14-day culture, MH strain: the few bacteria (arrow 1) are a part of otherwise in ‘empty’ walls (arrow 2). C. TEM picture, 14-day culture, MH strain: an intact bacterium (arrow 1) and a partly disintegrated bacterium (arrow 2) are both integrated in the wall structure (arrow 3). D. TEM picture, 14-day culture, MH strain: the bare walls consist of fine, dispersed fibers (arrow 1) and intensely stained dots (arrow 2). E. SEM picture, 14-day culture, MH strain: empty compartment walls. F. SEM picture, 14-day culture, MH strain: bacteria depleted compartment walls. G. SEM picture: 14-day old cultures (MH strain) showed large compartmentalized areas. H. cLSM transmission mode, 14-day culture (MH strain): ‘empty’ compartment walls under hydrated conditions.</p

Compartmentalization.

<p>A. SEM picture, 10-day culture, MH strain: solid, parallel, wall-like structures. B. SEM picture, 14-day culture, MH strain: the top sheet (region 1) is situated on vertically stacked walls (region 2). C. cLSM transmission mode, 14-day culture, MH strain: a dense, horizontal top plate (region 1) is located on top of vertically stacked walls (region 2). D. SEM picture, 14-day culture, MH strain: compartmentalized structure of aligned walls and cross-walls without top sheet. E. cLSM transmission mode, 14-day culture, MH strain: aligned bacteria form compartment walls. F. SEM picture, 14-day culture, MH strain: matrix (arrow 1) embedded bacteria (arrow 2) form compartment walls. G. cLSM picture, 14-day culture, MH strain: LIVE/DEAD staining of compartment wall forming bacteria show varying stages of membrane integrity (arrows). H. SEM picture, 14-day culture, MH strain: compartment structure with abundant bacteria (region 1) adjacent to an area with bacteria-depleted compartments.</p

Specific staining, time-course and development model.

<p>A. cLSM picture, 14-day culture, strain #49134: the EUB338 probe labels the compartment structure (red), while the bacteria are double-stained by the EUB338 probe and Syto59 (yellow). B. cLSM picture, 14-day culture, MH strain: Concanavalin A stains the compartment structure, but not the bacteria (arrow 1). C. cLSM picture, 14-day culture, strain #49134: the Sypro protein stain (green) and the Syto59 nucleic acid stain label both the bacteria (yellow) but not the compartment structure. D. cLSM picture, 14-day culture, strain #49134: the lipophilic stain Nile Red (green) does not label compartment walls, only diffuse biofilm matrix. E. SEM picture, 28-day culture, MH strain: huge aggregates with intact bacteria and strands continued to be present in long-time cultures. F. SEM picture, MH strain, overnight grown colony on agar. G. The model depicts the main development stages and their timely appearances in the context with the CFU time-course (MH strain).</p