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 (ρki, r, ρki – r) and the values of the kinematic force parameters (VE1, VE2, Vai) for each concrete position of the ki 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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UDC 656.1.086:614.864

Vasile Plămădeală, Vladimir Goian

Abstract. Almost a quarter of people killed in road accidents worldwide are the most vulnerable road users – pedestrians. Every year, more than 300000 pedestrians die on the world’s roads, which is about 23% of the total number of people killed in road accidents. In addition, millions of pedestrians are traumatized, some of them becoming disabled for life. The article includes a brief description of the driver-pedestrian relationship, road accident statistics involving pedestrians in the Republic of Moldova and in different geographical areas of the globe, modern practices and technologies applied in car construction by manufacturing plants to ensure pedestrian safety.

Keywords: pedestrian, pedestrian crossing, road accident, traffic accident, pedestrian safety, pedestrian collision, pedestrian collision.

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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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UDC 621.372:004.3:621.31

Natalya Turturica

Abstract. The paper deals with elaboration of hexaphase symmetrical components filters and their modeling to create microprocessor-assisted relay protection of self-compensating power lines. The theory is presented and the basic principial electrical schemes and mathematical models in the Matlab/Simulink of the filters of the hexaphase symmetric components are elaborated. The results of their simulation and testing at the computer are presented. The obtained results demonstrate the possibility of creating in the base on the elaborated filters of hexaphase symmetrical components the modern, efficient and high-sensitivity microprocessor-assisted relay protection of self-compensating power lines. What reacted not to phase electrical values, but symmetrical components of them.

Keywords: modeling of current filter, power transmission line, relay protection, transfer capacity of the line.

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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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UDC 621.37.001

Eugeniu Grigoriev, Vasile Tronciu, Nils Werner, Hans Wenzel

Abstract. This paper reports on the theoretical end experimental investigation of the output characteristics of a multisection master-oscillator power-amplifier (MOPA). It consists of a master oscillator (MO) composed by a gain section surrounded by two DBR sections monolithically integrated with a power amplifier (PA). We use a traveling wave equation model to calculate the optical output power in dependence on the current injected into the PA. The experimental results can be well explained with our theoretical analysis. For a finite front facet reflectivity of the PA the system is acting as a compound cavity.

Keywords: distributed Bragg reflector laser, DBR, master oscillator power amplifier, MOPA, feedback.

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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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UDC 004.056:004.4

Murimo Bethel Mutanga

Abstract. As ubiquitous computing becomes an increasingly inherent component of everyday life due to the rapid growth of communication technologies and globalization, threats against information systems have taken a more latent yet lethal dimension. This emergent digital security challenge has correspondingly motivated a proactive change in the software engineering process in recent decades. This change has inspired more intense research scrutiny on security as a crucial component of any software system. Moreover, in today’s virtual world of hyperconnectivity, the most significant vulnerabilities in modern information systems security are software centred. Nevertheless, research shows that software developers often lack the required knowledge and skills in secure software systems development (SSD). Such knowledge ensures that all the resultant software components of each development lifecycle are correctly implemented rather than merely following the SSD lifecycle. Also, the knowledge engenders software security consciousness as a professional attitude amongst developers. Therefore, investigating students’ awareness of SSD principles can generate insight into evolving the undergraduate software development curriculum – a path to building future career developers. The study used a voluntary online survey to recruit a sample of 76 undergraduate developers and employed a descriptive approach to data analysis. Among other findings, the study revealed that participants’ perception of the threat of software vulnerability impacts their attitude towards security on online and mobile platforms. And that though over 90% of the undergraduate developers took software vulnerability threats either “serious” or “extremely serious”, this disposition did not reflect the depth of their knowledge and experience in SSD.

Keywords: Cyber-security, Framework, Software, threat, ubiquitous-computing, vulnerability.

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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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