Modeling, Simulation and Monitoring of Electrical Contacts Temperature in Railway Electric Traction

The paper presents a mathematical modeling approach to determine the permanent regime temperature of an electric contact found in the supply system of the railway electric traction. Mathematical modeling is a basic procedure in the preliminary determination of parameters of interest in various fields of scientific analysis. The numerical modeling method used for determining the electric contact temperature represents the base for developing a finite-element thermal model. The simulation of the electric contact was verified by an experimental infrared investigation of an electric contact realized on a realistic laboratory setup. The results interpretation reveals a good synchronization between the calculated, simulated and measured temperatures.

DETERMINATION OF PARAMETERS OF INFORMATION PROTECTION AT THE ENTERPRISE IN CONDITIONS OF DESTABILIZING INFORMATION INFLUENCE

The subject of the article is the models of protection of official, commercial, confidential and other information, which is used by the officials of enterprises when making managerial decisions in terms of destabilizing informative influences. The aim of the study is to obtain an integral index, which characterizes the protection of necessary information, which is used by the officials of the enterprise when making managerial decisions in the presence of destabilizing information influences from the social networks, open sources and insiders. The task of this work are determinations of basic parameters, that characterize the system of defense of information of enterprise at the acceptance of administrative decisions a public servant in the conditions of destabilizing informative influences. The methods of researches are a probability theory and quality theory of differential equalizations. Results: on the basis of the observation and research of the activity of officials in the enterprises of different forms of ownership it was established that making managerial decisions by an official of the enterprise under conditions of destabilizing information influence is a relaxation fluctuation in the non-autonomous model of psychological arousal. An analysis of the dynamics of the sequence of influencing impulses on an official from existing information sources was conducted. An integral index, that determines a thresholding at that the system of informative defense of enterprise answers politicians of informative defense of enterprise at the acceptance of administrative decisions, is got. Conclusions: it was found that the threat of successful destabilizing information influence on management decision making by an official of the enterprise is determined by three parameters: the parameter, which determines the leakage of confidential information, the parameter, which determines the violation of the integrity of information and the parameter, which determines the blocking of access to information. It is noticed that the beginning of the emergence of a sequence of influencing destabilizing information influences on the enterprise determined by the content of the information at the initial moment of time (the effect of suggestion) and occurs over a period of time (lag effect).

Vacuum infrared dryer for drying fruit

The article is devoted to the study of infrared drying of products in a reduced pressure chamber using the convection effect. With the use of drying, canning of fruits, vegetables, herbs and meat is achieved, which reduces not only the volume, but also the weight of the processed raw materials. The paper presents the main parameters of drying products online, such as relative humidity, pressure, radiation intensity of infrared lamps, drying temperature. The uniqueness of this unit in comparison with similar dryers is a one-time treatment of the product with infrared rays under reduced pressure, convection of air flows inside the drying chamber and full automation of the drying process of any product of plant and animal origin. Determination of parameters and modes of drying was carried out on products of plant origin. During the experimental part, bananas and apples were used. In experimental studies, products such as bell peppers, apples and bananas with various slicing thicknesses were used. The greatest drying effect was obtained with a drying product thickness of 5 mm, and the worst with a product thickness of 10 mm. For example, pepper has decreased in weight from 79.84 grams. up to 23.43 gr., which is his weight loss by 70.65%.

Experimental Determination of Parameters of Nonlinear Electrical Load

The paper deals with issues of modeling nonlinear electrical loads of various types, such an uncontrolled rectifier, thyristor rectifier, thyristor power regulator and mixed equivalent nonlinear load. For these load types, existing analytical expressions were identified to determine the magnitudes of harmonic currents, and waveforms of currents were obtained during measurements in laboratory conditions with variable parameters of the grid impedance and load. The obtained results were compared, and it was found that the error in determining the magnitudes of harmonic currents can reach 60% for an individual load and 54% for an equivalent load. A more accurate method for determining the parameters of nonlinear electrical load is also proposed, which is based on the application of shunt harmonic filters. In laboratory conditions, it was found that when using the developed method, the error did not exceed 10% for an individual load and 14% for an equivalent load.

Experience in Optimizing the Location and Parameters of Multistage Hydraulic Fractures for a Multilateral Well Based on Reservoir Simulation

This work presents the approaches used for the optimal placement and determination of parameters of hydraulic fractures in horizontal and multilateral wells in a low-permeability reservoir using various methods, including 3D modeling. The results of the production rate of a multilateral dualwellbore well are analyzed after the actual hydraulic fracturing performed on the basis of calculations. The advantages and disadvantages of modeling methods are evaluated, recommendations are given to improve the reliability of calculations for models with hydraulic fracturing (HF)/ multistage hydraulic fracturing (MHF).

Determination of Parameters for an Entropy-Based Atrial Fibrillation Detector

Entropy algorithm is an important nonlinear method for cardiovascular disease detection due to its power in analyzing short-term time series. In previous a study, we proposed a new entropy-based atrial fibrillation (AF) detector, i.e., EntropyAF, which showed a high classification accuracy in identifying AF and non-AF rhythms. As a variation of entropy measures, EntropyAF has two parameters that need to be initialized before the calculation: (1) tolerance threshold r and (2) similarity weight n. In this study, a comprehensive analysis for the two parameters determination was presented, aiming to achieve a high detection accuracy for AF events. Data were from the MIT-BIH AF database. RR interval recordings were segmented using a 30-beat time window. The parameters r and n were initialized from a relatively small value, then gradually increased, and finally the best parameter combination was determined using grid searching. AUC (area under curve) values from the receiver operator characteristic curve (ROC) were compared under different parameter combinations of parameters r and n, and the results demonstrated that the selection of these two parameters plays an important role in AF/non-AF classification. Small values of parameters r and n can lead to a better detection accuracy than other selections. The best AUC value for AF detection was 98.15%, and the corresponding parameter combinations for EntropyAF were as follows: r = 0.01, n = 0.0625, 0.125, 0.25, or 0.5; r = 0.05 and n = 0.0625, 0.125, or 0.25; and r = 0.10 and n = 0.0625 or 0.125.

Antifungal Efficacy of Redox-Active Natamycin against Some Foodborne Fungi—Comparison with Aspergillus fumigatus

The fungal antioxidant system is one of the targets of the redox-active polyene antifungal drugs, including amphotericin B (AMB), nystatin (NYS), and natamycin (NAT). Besides medical applications, NAT has been used in industry for preserving foods and crops. In this study, we investigated two parameters (pH and food ingredients) affecting NAT efficacy. In the human pathogen, Aspergillus fumigatus, NAT (2 to 16 μg mL−1) exerted higher activity at pH 5.6 than at pH 3.5 on a defined medium. In contrast, NAT exhibited higher activity at pH 3.5 than at pH 5.6 against foodborne fungal contaminants, Aspergillus flavus, Aspergillus parasiticus, and Penicillium expansum, with P. expansum being the most sensitive. In commercial food matrices (10 organic fruit juices), food ingredients differentially affected NAT antifungal efficacy. Noteworthily, NAT overcame tolerance of the A. fumigatus signaling mutants to the fungicide fludioxonil and exerted antifungal synergism with the secondary metabolite, kojic acid (KA). Altogether, NAT exhibited better antifungal activity at acidic pH against foodborne fungi; however, the ingredients from commercial food matrices presented greater impact on NAT efficacy compared to pH values. Comprehensive determination of parameters affecting NAT efficacy and improved food formulation will promote sustainable food/crop production, food safety, and public health.