Signal denoising through topographic modularity of neural circuits

Information from the sensory periphery is conveyed to the cortex via structured projection pathways that spatially segregate stimulus features, providing a robust and efficient encoding strategy. Beyond sensory encoding, this prominent anatomical feature extends throughout the neocortex. However, the extent to which it influences cortical processing is unclear. In this study, we combine cortical circuit modeling with network theory to demonstrate that the sharpness of topographic projections acts as a bifurcation parameter, controlling the macroscopic dynamics and representational precision across a modular network. By shifting the balance of excitation and inhibition, topographic modularity gradually increases task performance and improves the signal-to-noise ratio across the system. We show that this is a robust and generic structural feature that enables a broad range of behaviorally-relevant operating regimes, and provide an in-depth theoretical analysis unravelling the dynamical principles underlying the mechanism.

A Probabilistic Approach to Growth Networks

Single-class closed queueing networks, consisting of infinite-server and single-server queues with exponential service times and probabilistic routing, admit product-from solutions. Such solutions, although seemingly tractable, are difficult to characterize explicitly for practically relevant problems due to the exponential combinatorial complexity of its normalization constant (partition function). In “A Probabilistic Approach to Growth Networks,” Jelenković, Kondev, Mohapatra, and Momčilović develop a novel methodology, based on a probabilistic representation of product-form solutions and large-deviations concentration inequalities, which identifies distinct operating regimes and yields explicit expressions for the marginal distributions of queue lengths. From a methodological perspective, a fundamental feature of the proposed approach is that it provides exact results for order-one probabilities, even though the analysis involves large-deviations rate functions, which characterize only vanishing probabilities on a logarithmic scale.

Modification of carbohydrates of food raw materials in the process of thermoplastic extrusion (review)

Extrusion can be considered not only as an effective technology for processing agricultural raw materials into feed and food products, but also as a thermo-mechanical method for modification of the chemical properties of biopolymers. Carbohydrates are the most represented class of organic compounds in raw materials processed by the agro-industrial complex. The assessment of the influence of the processing factor on the final physicochemical and technological properties of various types of carbohydrates included in the chemical composition of raw materials or used as mono-ingredients is an actual task for the food industry. The review considers the issues of extrusion modification of starch in terms of the difference in the properties of amylose and amylopectin as well as the presence of lipids and organic acids in the reaction system. Processes of macromolecular degradation, gelatinization, esterification and the formation of new chemical bonds in dependence on the conditions of extrusion and the composition of mixtures are discussed. The results of studies of the influence of extrusion cooking on the changes in the physicochemical properties of non-starchy polysaccharides, cellulose, araboxylans, inulin, pectin, chitosan, and gums of various origins are presented. It has been shown that extrusion and varying of its operating regimes can significantly affect the nutritional value of extrudates including changing the glycemic index, inactivating antinutritional factors, or increasing their content in extrudates.

The swirl number as a method for determining the optimal operating mode of the micro hydro turbine

The paper presents the data of a detailed study of the flow characteristics behind the runner of an air model of a propeller-type micro hydro turbine with varying operating modes from partial load to severe overload. Detailed measurements of the flow field distributions were carried out using an automated system for contactless optical diagnostics (LDA). The obtained data made it possible to link the identified features of the development of the flow structure when changing the operating mode of the installation with the nature of the evolution of the integral swirl number that determines the state of the swirled flow. Eventually, the work results can be used in the elaboration of recommendations for extending the regulation range of the operating regimes of hydraulic microturbines and providing their high efficiency.

Diagnosis of Mechanical Faults Affecting a Hydroelectric Group by Vibration Analysis

This article deals with a diagnostic approach based on a predictive / conditional maintenance approach of a hydroelectric group. The technique used is based on the spectral analysis of the vibration signals, as well as on the orbital analysis of the bearings displacements. To do this, test protocols in different operating regimes are carried out, based on the collection of data measured according to the multisensor approach, the aim of which is to identify the predominant faults. The positions of the sensors are placed as close as possible to the bearings on the rigid structure of the hydroelectric group in accordance with the recommendations of standard ISO 10816-5. The evaluation approach is based on the analysis of the amplitudes of the vibration speeds, the aim of which is to identify the type of faults, as well as on the bearing displacement indicators in order to classify them in the pre-established zones according to thresholds recommended by the Standard. Therefore, a recommended tuning intervention can be planned in order to restore the unit to its proper operating condition, the aim of which is to increase its service life and improve fuel efficiency. Keywords—Diagnostic, Vibration analysis, Hydroelectric group, Multi-sensor approach, Standard

The study of instabilities role of plasma in the high-voltage discharge formation initiated by optical radiation at high pressures in high-voltage optically triggered switches

The paper presents the experimental results of triggering a high-voltage gas gap by YAG: Nd3+ laser radiation. The gas gap was used as the primary switch of a high-current pulsed e-beam RADAN-type accelerator. As a result, an operating regime when the instability and delay time appeared to be minimal was experimentally found. The developed gas gap and the found operating regimes sustain the switching instability no more than 0.3 ns. The physical mechanisms determining the switch-on delay and the obtained level of instability are discussed.