https://doi.org/10.52326/jes.utm.2022.29(2).01

UDC 621.833:621.89

Ion Bostan, Petru Stoicev, Gheorghe Poștaru, Maxim Vaculenco, Alexandru Buga, Mihail Kulev, Andrei Poștaru, Andrei Platon

Abstract. This paper deals with the theoretical-experimental model of the tribological behavior of the contact elements in precessional gears (PG) in the functions of conjugate profiles of linear velocities “convex-concave” or “convex-convex” for the corresponding geometric parameters (ρ_ki, r, ρ_ki – r) and the values of the kinematic force parameters (V_E1, V_E2, V_ai) for each concrete position of the k_i points. The calculation of the constructive-functional and kinematic parameters of the “roller-shoe” and “roller-roller” elements of the tribocouple were adjusted for the experimental verification tests on the SMT-1 installation and adapted to the specific test conditions of the tribocouples with conformal contact of gear teeth made of plastics, which will be subjected to sliding friction and rolling processes of the concrete tribocouple elements.

Keywords: precessional transmission, precessional gearing, contact load, tribomodel, sliding (rolling) friction, experimental modeling of the precessional gearing, tribological parameters, friction coefficient and force, power loss, mechanical efficiency.

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https://doi.org/10.52326/jes.utm.2022.29(2).03

UDC 621.314.222

Sveatoslav Postoronca, Dmitrii Zaitsev, Mihai Tirsu, Irina Golub, Danila Kaloshin

Abstract. The development of power engineering assumes the increasing flexibility of power networks through the use of various kinds of FACTS, controlled by means of power electronics and being elements of the Smart Grid. These kinds of devices can be attributed to controllers such as UPFS and „Sen” Transformer (ST), which provide regulation of voltage and power flows in networks. Due to the relevance of this topic, technical solutions are proposed that perform similar functions, which implies the need for a comparative analysis of such developments in order to optimize energy characteristics of the equipment. The scope of the paper is to develop and study a regulating transformer which belongs to the „Sen” family, but possessing the extended range and higher control accuracy. Carrying out research, mode parameters of the device were treated, as well as typical power was determined.

Keywords: booster transformer, load, voltage control, active power, reactive power compensation, operation mode control.

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https://doi.org/10.52326/jes.utm.2022.29(2).05

UDC 620.92:621.31

Corina Guțu-Chetrușca, Dumitru Braga

Abstract. The main global concern in the energy sector is the substitution of fossil fuels and the mitigation of climate change – the transition to the carbon neutrality of the economy. For the power sector, the main solution for this transition is to use hydro, wind and solar energy sources, which have a high energy potential, including in the Republic of Moldova. Variable renewable energy sources, wind and solar, due to their intermittent nature have a significant impact on the power system and the quality of electricity. The necessary measures to reduce the impact of the variability of these sources are presented. The most appropriate measure would be to use pumped storage hydropower plants. The water losses from their accumulation lakes were appreciated. That constitutes approx. 1 … 2 m3/MWh which is considerably lower than the losses from the Thermal Power Plants with steam turbines.

Keywords: variable renewable energy sources, energy storage, water losses.

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https://doi.org/10.52326/jes.utm.2022.29(2).07

UDC [004.7:621.39]:001.89

Titu-Marius I. Băjenescu

Abstract. The constant evolution in telecommunications is recognized both as a market driver and as a driver for R&D, since R&D activities are built to support consumer and business demands. The market pressures and recent past recessions have considerably shifted the focus of companies to product development and incremental research. This current focus on short term gains has paved the way for applied research to the furthest extent. Research and technological development, which is a founding block of any field of science and technology, was explained from the point of view of ICT with a primary focus on the telecom industry. The research ecosystem along with its shortcomings were also presented. It is important that governments and the ICT industry re-evaluate the R&D ecosystem and consider having both a 3 to 5-year view along with a 30 to 40-year long vision. 5G technology started to roll out effectively to ordinary users in 2019 (development of this technology started in April 2008), and in 2020 it was expected to spread to even more countries, and then in a few years it will be global. This is despite various studies that point out that 5G radiation will have negative effects on human health (which has also been claimed for 4G and 3G), while organisations such as the US Communications Commission (US FCC) and almost all similar organisations state that 5G radiation has no significant effects on human health. Another concern is the security of communications over 5G networks, especially equipment sold by China. Australia and the UK – in early 2019, took steps to restrict or eliminate the use of Chinese-sourced equipment in their 5G networks. Also in 2019 the US via the FBI and the UK via Government Communications Headquarters (GCHQ) other intelligence services, began to get more involved in changing surveillance standards. Including at the NATO meeting in London in December 2019, 5G network security and development was discussed. In addition to high download speeds, the 5G network also has a low “air latency” (between phone and antenna) of 8-12 milliseconds.

Keywords: 5G mobile communication, robust research ecosystem, 6G, wireless network, NTT DOCOMO, R & D process, significantly faster speeds, Nokia 2G 6G, making 6G a reality.

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https://doi.org/10.52326/jes.utm.2022.29(2).09

UDC 004.8/.9:576

Silvia Munteanu, Viorica Sudacevschi, Victor Ababii

Abstract. This paper deals with a synthesis method of membrane computer systems inspired from the biological cells structure. The functional concept of the computer system is based on the internal structure, chemical transformations and the way of interaction between living cells. Thus, the computer system is composed of a set of autonomous, homogeneous or heterogeneous computing cells, which communicate with each other in synchronous or asynchronous mode. The algorithmic complexity of the solved problem depends on the knowledge gained, the rules of data processing and the computer system topology. It is proposed the sequence of operations for the synthesis of membrane computer systems with implementation in reconfigurable FPGA architectures which includes: analysis of behavioural models of living organisms and their interpretation in artificial intelligence models; structure and functional description of the computing cell; cell modelling and performance evaluation using Petri nets; Van diagram of the membrane computer system topology; formal description of the membrane computer system topology by applying the JSON formatting language; validation, functional modelling and performance evaluation of the membrane computer system topology using Petri nets; Hardware Description Language (HDL) code of the cell from which the principle electrical diagram and the time diagrams are obtained; implementation of the computer system in the FPGA circuit.

Keywords: computational topology, cognitive properties, evolutionary computing, FPGA, HDL, knowledge, membrane computing, nature-inspired computing, natural computing, P-Systems, Petri nets, swarm intelligence, JSON.

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https://doi.org/10.52326/jes.utm.2022.29(2).11

UDC 691.32:006

Gheorghe Croitoru

Abstract. The article presents the problems related to the application of the provisions of the new European standards EN for concrete production, after the withdrawal of the obsolete national standards GOST regarding the correspondence of the classes to the concrete marks. In the context of the application of harmonized standards, there has been a need to establish the correspondence of classes to concrete marks, in order to help design and construction companies to correctly establish the strength mark of concrete to the corresponding class of concrete. The concrete class establishes the normative resistance of concrete for the calculation of constructions, for the service limit state, the prismatic resistance to compression adopted as normative resistance. The ratio between concrete classes and marks, in terms of compressive strength, is determined by the normative coefficient of variation V = 13.5%. The degree of homogeneity of the quality of the concrete is determined according to the values of the standard deviation σ and the average compressive strength of the concrete. As a result of the research, intermediate classes of concrete have been identified, which are not indicated in the normative documents, related to the production of concrete.

Keywords: basic parameters, coefficient of variation, compliance criteria, concrete class, concrete mark, compression strength, correspondence, medium values, standard deviation.

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https://doi.org/10.52326/jes.utm.2022.29(2).13

UDC 620.95:633.282

Nicolae Daraduda, Grigore Marian

Abstract. Miscanthus is a Poaceae family perennial crop of C4 bioenergy characterized by the multilateral use potential, including the production of biofuels. The paper aimed to study the opportunity to use the biomass generated by two Miscanthus genotypes: Miscanthus × giganteus and Miscanthus sinensis in the production of densified solid biofuels. We quantified the biomass generated by crops that were 5 years old, harvested from both genotypes after the vegetation period, the year 2020. Samples were taken from the experimental lots of the Alexandru Ciubotaru National Botanical Garden (Institute) from the Republic of Moldova in autumn, immediately after the initial onset of senescence and in spring of the following year, before the start of the growing season. The results showed that the above-ground biomass generated by both Miscanthus genotypes harvested in spring had had significantly higher quality characteristics compared to the biomass harvested in autumn. Virtually all qualitative indices of the Miscanthus × giganteus biomass harvested in spring comply with the requirements of the ENPlus international standards for densified solid biofuels. The Miscanthus sinensis biomass, both, had lower indices than the Miscanthus × giganteus biomass from both qualitative and quantitative points of view and the former can be used as a filler in various mixtures of raw material for the production of solid biofuels.

Keywords: energy crops, Miscanthus x giganteus Titan, Miscanthus sinensis, biomass properties

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https://doi.org/10.52326/jes.utm.2022.29(2).15

UDC 621.798.147:339.37:004 (430)

Stan Lukas Bührdel, Patrick Siegfried

Abstract. This research paper discusses how RFID technology could improve current deposit bottle logistic processes in food retailing and which obstacles impede successful implementations. Research Methodology include desk research: Library, EBSCOhost, wiso.net, Google Scholar, Scientific Journals, Statista, SpringerLink. Implementation of RFID is potentially beneficial, but same obstacles remain outlook. To validate the conclusion further studying and practical proof of concept are necessary. Contributions: supply chain management, return logistics, food retail, beverage industry.

Keywords: deposit bottle, food retailing, return logistics, reusable packaging, RFID.

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