https://doi.org/10.52326/jes.utm.2022.29(1).01

UDC 621.382:546:621.3.049.77

Eduard Monaico

Abstract. The paper is focused on electrochemical approaches for nanostructuring of semiconductor compounds with further applications in nano – microelectronic devices. A cost-effective technology for nanowires and nanotubes obtaining by pulsed electrochemical deposition is presented. Functionalization of elaborated nanostructures with gold or platinum via electroplating improves the properties of the nanostructures. An optimization of the varicap design to increase the capacitance is proposed and discussed as well as the optimization of pulsed electrochemical deposition of several hundred micrometer long Pt nanotubes is performed. Herein, the elaboration of contacts to GaAs nanowires via different approaches for photoelectrical investigations is reported.

Keywords: electrochemistry, nanostructures, nanowires, photodetector, contacts, varicap device.

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https://doi.org/10.52326/jes.utm.2022.29(1).03

UDC 621.83:678.073

Ion Bostan, Petru Stoicev, Alexandru Buga, Gheorghe Postaru, Nicolae Trifan, Andrei Platon

Abstract. Selecting gear materials is a great challenge for engineers. Gear teeth are subject to difficult and severe loading conditions. Simultaneous action of alternating normal and tangential dynamic stresses occurs, contact deformations accompanied by sliding friction. Gears are subject to increased requirements in terms of strength, geometric accuracy, dimensional stability, and durability. For the manufacture of gears, especially from thermoplastic materials, a theoretical argumentation of the materials is needed. An extensive study of thermoplastic materials, around the world needs to be done and the most efficient tribological couples to be chosen in terms of heat transfer from the gear zone, operation with or without lubrication, and gear life. In this paper, a theoretical synthesis of the Steel / Plastic, Plastic / Plastic, Plastic/Steel tribological couples is made, which were used in conformist and non-conformist experiments. Therefore, selected tribological couples are supposed to be used in the Precessional Transmissions applications.

Keywords: gear materials, sliding friction, manufacture of gears, thermoplastic materials, heat transfer, tribological couples, gear life, theoretical synthesis.

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https://doi.org/10.52326/jes.utm.2022.29(1).05

UDC 662.769.2:620.9

Titu-Marius I. Băjenescu

Abstract. The article examines the problem of the hydrogen market – from production to how to use it, as well as the prospects for the development of these energy sources. To combat climate change, more and more countries are investing in low-carbon energy, which is produced from renewable sources and is therefore neutral throughout the chain. Thus, the global hydrogen market is growing. Hydrogen can help decarbonise industrial sectors and combat climate change, either as an environmentally friendly fuel in the transport sector or as a means of reducing emissions in steel production and many other industries. Hydrogen can also play a vital role in energy transport. But even though hydrogen does not pollute itself, because its combustion releases only water vapour, it emits CO2 when fossil fuels are used for its production (“Grey” hydrogen). “Green” hydrogen is still in its infancy: less than 1% of global hydrogen production, which is itself only 2% of global energy consumption. “Green” hydrogen is very expensive to produce, considerably more than “Grey” hydrogen.

Keywords: Hydrogen energy, ”Green hydrogen”, “Grey” hydrogen, present challenge, Hydrogen economy, CO2-free hydrogen, Use of hydrogen.

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https://doi.org/10.52326/jes.utm.2022.29(1).07

UDC 614.8.084

Serghei Peancovschii

Abstract. This article presents methods for timing the key milestones and timing of the emergency response. A graphic model is proposed that allows you to determine the stage and time of the response process, regardless of the nature of the ongoing processes manifestation. The model allows a detailed analysis the process effectiveness of responding to various emergencies. And it also allows to determine the boundaries of responsibility areas to optimize management decisions of the response process, increasing its quantitative and qualitative values. The presented mathematical models exclude errors in assessing the effectiveness of the response. The developed mathematical apparatus can be used for effective management of emergency response units.

Keywords: decision making, safety, timing, emergency situations, areas of responsibility, emergency response.

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https://doi.org/10.52326/jes.utm.2022.29(1).09

UDC 616.7:656.18.05: 331.101.1(669)

Adekunle I. Musa-Olokuta, Collins Nwaokocha, Adeola S.Shote, Samson A. Aasa

Abstract. Motorcycles have become a mean of transportation in our rural and urban area in Nigeria. This cross sectional study was conducted in Abeokuta Ogun State to assess the work-related musculoskeletal disorders (WRMSDs) among the motorcyclist between October 2021 and January 2022 using snowball techniques. A structured modified Nordic Musculoskeletal disorder questionnaire (SNMQ) was administered to four hundred and fifty (450) motorcyclists. The result shows that 91.6% (412) of the motorcyclist participated. Furthermore, 76.1% of the cyclist experienced daily pains and 81.6% reported major pains in body parts. However, the results also show that major affected body regions were lower back (81.6%), leg (61.2%), upper back (82.0%), shoulder (55.1%), neck (82.5%), knee (73.3%), wrist/hand (98.8%), thigh (91.3%), ankle/feet (78.9%), ears (80.3%), eyes (59.0%), head (63.1%) respectively. The study concluded that high prevalence of WRMSDs existed among the commercial motorcyclists as a result of working hours, sitting posture, smoking and alcoholic drinking. Reduction of these symptoms could be achieved through the reduction of working hours.

Keywords: WRMSDs, motorcyclist, smoking, alcohol, tiredness, break, shoulder, thigh.

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https://doi.org/10.52326/jes.utm.2022.29(1).11

UDC 551.55:504.3(478)

Octavian Mangos, Vasile Rachier, Ion Sobor, Vadim Cazac

Abstract. The study is focused on three districts in the northern region of the Republic of Moldova – Briceni, Edinet and Ocnita. The maps were calculated and presented in terms of average annual wind speed and wind power density at a height of 100 m above ground level, wind rose and Weibull wind speed distribution. In the calculations performed for the three analyzed districts it was found that the average annual wind speed is between 6.84 and 7.35 m / s, and the wind power density – between 450 and 593 W / m2. The highest annual average speed equal to 7.35 m / s was identified in Ocnita district. At the same time, having the maps of the wind speed and the power density, the convenient locations for the construction of the wind farms can be selected. For each district involved in the study, a location with a pronounced wind potential was identified, recommended for the location of any wind farms.

Keywords: wind speed; power density, wind atlas method, software package WAsP 9.1.

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https://doi.org/10.52326/jes.utm.2022.29(1).13

UDC 637.146.34:667.275.5

Liliana Popescu, Aliona Ghendov-Moșanu, Alexei Baerle, Alexandra Savcenco, Pavel Tatarov

Abstract. The article elucidates the possibility of using the yellow dye, obtained from saffron petals (Carthamus Tinctorius L.) in the food industry. This powdered dye, added to yoghurt in concentrations of 0.3 – 0.4%, in addition to its yellow color, gives the yoghurt samples a light aroma of saffron flowers and demonstrates high stability during storage at 4° C. for 28 days. The values of the chromatic coordinates, L *, a *, b *, of the yogurt samples did not undergo considerable changes during the storage stage, the color difference ΔE being ≤ 0.79, which indicates a high stability of the dye in yogurt. samples. The chromatic analysis data correlate with the results obtained by the reverse phase HPLC method, which identified the presence of four intact yellow chalcones in the yoghurt. The results of this study will encourage the cultivation of saffron, the extraction of natural dyes and their use in the food industry.

Keywords: chromaticity coordinates, color analysis, food additive, natural food.

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