Papers by Author: Bebe Adrian Olei

Abstract: The condition of a dynamic machine (equipment) can be estimated at the current level, by measuring the vibration levels. Each component of a machine produces a vibration with one or more specific frequencies. Knowing the components of the spectrum of frequencies of the global vibration, it is possible to determine which of the components of the moving assembly the problem occurred. Thus, by measuring the vibration, a multitude of defects can be detected, for a wide variety of dynamic machines. Unlike other diagnostic devices, spectrum analyzers have the widest use in the evaluation of vibrations and specific stresses on fixed structures or on rotor blades. Other experiments evaluate the natural frequencies of the rotors, the influence of the cavity of the rotor-stator interaction. Model or prototype studies establish the influence of pressure pulsations at partial load for radial axial turbines [5]. In the work, the vibrational behavior of a Kaplan hydraulic turbine with 6 rotor blades of high power (P=200MW, Dn=9.5m), was analyzed when mechanical failures (wear) appeared after several years of operation, the graphs being taken from the diagnostic system of the studied hydrogen generator.

Abstract: Significant industrial settlements along the main Europe inland waterways are going to be analysed based on NACE codes per port (maritime and inland) in ports and along the waterway. The industrial areas around ports have been analysed and different KPIs were developed, like distance from industrial areas for handling infrastructure, throughput or industrial segments. Furthermore, an analysys concerning the link between the length of the waterways and the land usage areas has been performed as well as the influnce of the population density on the land usage area ratio.

Abstract: This work presents some relevant data regarding the amount of goods that have been transported inside the European Union borders using the inland waterway transport. There are also presented the goods quantities that were transited the Romanian harbours in the last years. In accordance with the Eurostat inland waterways freight transport report for the 2016-2019 period, the Romanian market was estimated in 2019 at the approximate value of over 33.200 thousand tones, which situated Romania on the 5^th position among the European states. More, this quantity represented a total increase of 11.9% reported to the previous year. The biggest quantities of transited goods are represented by cereals, then crude mineral products and then oil and gas products.

Abstract: This paper aims to identify the needs for updating the European Welder Training Guideline in order to introduce chapters for new digital innovative tools that can be used both in theoretical and practical training of welders. The objective of the revision of curriculum in the context of digital tools is to boost the digital skills of trainers, both youngsters (I-VET) and older personnel seeking further training (C-VET), thus targeting the issues raised during COVID-19 pandemic crisis as well as to increase the attractiveness of secondary/vocational schools and innovativeness of learning programmes. The paper present a research among VET school teachers for identify in what extent the new theoretical and practical digital tools can be implemented in order to increase the level of digital competences of the teachers as well as digital and professional competences of the learners.

Abstract: In the research activities on the barium monoferrite pyrosynthesis, an important place is occupied by TG and DTA analysis. The effects of different hematite (α-Fe₂O₃) granulations on the BaFe₂O₄ pyrosynthesis temperature were followed. Four types of commercial hematite powders were used, the difference between them being the fineness of the powder granules and the purity. Only one type of commercial barium carbonate (BaCO₃) powder was also used as a barium additive in the BaFe₂O₄ pyrosynthesis. Each of the 4 types of α-Fe₂O₃ with BaCO₃ were subjected to the homogenization process in a planetary mill for a more intimate mixing of the powders in order to obtain error-free results regarding the pyrosynthesis reaction. To determine BaFe₂O₄ pyrosynthesis temperature, a derivatograph device was used. All the data obtained with this thermal device were digitally processed in order to extract the two TG and DTA curves. The protective atmosphere in the furnace was nitrogen. BaFe₂O₄ pyrosynthesis temperatures recorded different values for the four mixtures, depending on the particle size of the α-Fe₂O₃ powders, protective atmosphere from furnace and the mixing conditions. The effects of Fe₂O₃ oxides on the BaFe₂O₄ pyrosynthesis temperature is observed when are used very fine hematite powders in mixtures, obtaining a reduction of pyrosynthesis temperature up to 16% compared to the mixture where the size of the hematite is coarser.

Abstract: FDM printing is based on resistance to heat of the polymer filament, which starts in a viscous state and is extruded from nozzle to the printing area. The printing area is hot around 70°C for a better adherence of the deposited polymer and for slow cooling of it. The later deposited layers will experience faster cooling and the characteristics of the polymer will suffer light changes. The paper aims to present the results of a preliminary research regarding the double source successive heating and double source hybrid heating of the extruded polymer in FDM process. There were used two distinct heat sources, the resistive source mounted in the extrusion nozzle and IR lamp heat source placed in the printing chamber. The first heating, which acts during the extrusion process, is a hybrid heating and it is developed inside the extrusion nozzle (hot-end); it is given by the resistive heat source by the IR lamp. After the extrusion, during the deposition process and after the deposition process, the heating of the polymer continues due to the IR lamp. The difference between the printing with IR heating and without IR heating was monitored. A decreasing of about 5-8% of the material stiffness was noticed when the IR lamp was introduced. The material became more viscous and the bonding of the successive layers was improved. DSC analysis has been performed in both cases: with and without IR heat source. The evolution of the elastic modulus proved a decreasing of the plasticity during the simple printing process. The decreasing was less (at least by about 25%) when used IR heat source. The elongation viscosity was analysed and its values were decreasing while the temperature was increasing that took place. The decreasing was produced by the reduction of the elasticity, when the chain branches were decreasing their length. The decreasing is more pronounced while the increasing of the temperature. A low difference (of about 2-5%) was observed to the mechanical characteristics after tensile tests.

Abstract: This work presents some logistics and transportation challenges that were solved by 3 different student groups from 3 different European entities. These groups were: the STC Group, from The Netherlands, made of 12 students; the FHOO Group, from Austria, which comprised a number of 10 students and the IMST Group from Romania, made of 12 students. Each of the group had a specific task of finding the best logistic and transportation solution for each of their task. Also, they need to take into account several important parameters like air pollution problem, the shortest way of reaching to destination, the way of transport and others, which were decisive in choosing the right solution.

Abstract: This work presents some relevant data of the last period for the transport and logistics market from Romania. The Romanian transportation and logistics market is currently estimated at the value of over 30 billion lei (approximately 6.7 billion euros), with the biggest 20 players having a market share of almost 20%. The most concentrated area for the storage of the transported goods is in Bucharest, the capital city and around some cities like Timisoara, Cluj, Ploiesti, Brasov and Pitesti. There are also other cities like Oradea, Sibiu and Arad, that are on full expanding process.

Abstract: In this paper, BaFe₂O₄ was prepared from BaCO₃ and Fe₂O₃ powders through the solid state reaction method. This method starts by mixing the barium carbonate and iron oxide in order to homogenize the raw materials and takes place in a wet medium. For a better homogenization of BaCO₃ and Fe₂O₃ powders and in order to reduce the monoferrite formation temperature, it was used the mechanical alloying process for 3 and 9 hours in a high energy ball mill. Particle size distributions of the milled powders were analyzed by a BROOKHAVEN 90PLUS device. To understand the phase formation temperature, thermogravimetry analysis was carried out. The phase identification of the calcined powder was carried out by D8 Discover Bruker X-ray diffractometer. The results showed that once with the reduction of powders particle size, in the mechanical alloying process, the temperature of the solid state reaction of barium monoferrite was also reduced.

Abstract: There are several innovations to be found in the inland waterway sector. European Federation of Inland Ports EFIP defines trends in Inland Ports and Current EU Policy Developments in 2014. The trends include urban logistics, biomass transports, as well as the transportation of heavy cargo. The Transport White Paper of 2011 targeted for freight transport to shift from road to rail and IWW by more than 50% by 2050. The described technological and organizational as well as logistic trends are linked and evaluated regarding their impact onto model variables of the different transport models and tools employed. Technological advancements have an impact on organizational and logistics issues and cannot be discussed independently from these topics. The analysis is performed for each trend individually and does not take into account the different maturities and interdependencies among the different trends evaluated.