Learning short synfire chains by self-organization

A model of cortical neurons capable of sustaining a low level of spontaneous activity is investigated. Without learning the activity of the network is chaotic. We report on attempts to learn synfire chains in this type of network by introducing a Hebbian learning mechanism and exciting a small set of neurons at random intervals. We discuss the types of instabilities that can arise and prevent the formation of long synfire chains and also discuss various biologically plausible mechanisms which to some extent cure these instabilities.     

A new variety of low-linolenic rapeseed oil; Characteristics and room-odor tests

Two Canadian rapeseed oils, “Westar” and “low-linolenic”, supplied by the Canola Council were studied and compared with a French rapeseed. The linolenic acid content of the low-linolenic variety is about 3%. This drop in the C18∶3 is completely compensated for by an increase in the C18∶2. Seventy-two percent of the triglycerides with at least one linolenic chain disappeared. A strong increase in the OOL and OLL was observed. The room-odor tests showed that the “low-linolenic” had a significantly higher odor score than the French rapeseed and the “Westar”, both of these being very similar. A fruity odor dominated in the “low-linolenic”, and the fishy painty odors were particularly reduced.     

Multifunktionales Batteriespeichersystem

In the national research project “Multifunctional Battery Storage System (MBS)” open questions were answered concerning the technical feasibility and profitability of a grid-connected battery storage system using a vanadium-redox-flow battery in combination with the renewable power generation plants PV and small wind power (Sterrer et al., Multifunktionales Batteriespeichersystem—MBS-Endbericht. Industrielle Forschung im Rahmen der österreichischen Programmlinie Neue Energie 2020, 3. Ausschreibung, noch nicht veröffentlicht, 2013). The technical implementation and the demonstration operation of the pilot plant over a period of two years showed that the battery storage system is suitable for intelligent marketing of renewable energy as well as the provision of system services for grid stabilisation. However, the investigation of different operating strategies of the pilot battery-storage system, a large scale storage system and pooled PV/battery storage systems as virtual power plant for the participation at the energy trading market and energy reserve market showed that all operation strategies being considered in this study may not be profitable in foreseeable future. However, if the costs of the battery storage system can be reduced to about 250 €/kWh until the year 2030, the application of the vanadium-redox-flow battery in particular in large-scale storage plants (e.g. 10 MW, 100 MWh) for the participation at the energy reserve market seems realistic.     

Reversible Cluster Aggregation and Growth Model for Graphene Suspensions

We present a reversible cluster aggregation model for 2‐D macromolecules represented by line segments in 2‐D; and, we use it to describe the aggregation process of functionalized graphene particles in an aqueous SDS surfactant solution. The model produces clusters with similar sizes and structures as a function of SDS concentration in agreement with experiments and predicts the existence of a critical surfactant concentration (C_crit) beyond which thermodynamically stable graphene suspensions form. Around C_crit, particles form dense clusters rapidly and sediment. At C ? C_crit, a contiguous ramified network of graphene gel forms which also densifies, but at a slower rate, and sediments with time. The deaggregation–reaggregation mechanism of our model captures the restructuring of the large aggregates towards a graphite‐like structure for the low SDS concentrations. © 2017 American Institute of Chemical Engineers AIChE J, 63: 5462–5473, 2017     

Aerosol Retention in the Vicinity of a Breach in a Tube Bundle: An Experimental Investigation

This article summarizes the main results of a bench-scale program focused on experimentally assessing the aerosol retention near the tube breach in a tube bundle. The major variables investigated were particle nature (polydispersed TiO ₂ agglomerates vs. solid, monodisperse SiO ₂ spheres) and Re _D (0.8?2.7· 10 ⁵ ). In addition, comparisons to other data sets provided insights into the particle aerodynamic size effect on retention efficiency. Results showed that particle nature substantially affects aerosol retention in the tube bundle: mass retention efficiency was low for TiO ₂ agglomerates (less than 30%) whereas it was much higher for SiO ₂ particles (around 85%). Retention efficiency is also affected by Re _D : its sensitivity was found to follow a log-normal behavior with a maximum retention attained at Re _D near 1· 10 ⁵ . This evolution with Re _D was similar for both types of compounds. Particle size also influences retention efficiency: the bigger the TiO₂ agglomerates the lower retention efficiency (no data were available for SiO ₂ ). Among all these variables, particle nature was noted to have a prime importance for in-bundle retention, whereas Re _D and particle aerodynamic size, although also affect retention efficiency, did not play such a key role. In light of the results, the presence of retention-inhibiting mechanisms such as fragmentation, resuspension or bouncing has been discussed. The data recorded will enhance the overall understanding of the governing mechanisms involved and will serve as a database against which compare model predictions. Nevertheless, further experimental data would be desirable to set up a sound database.