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Vol. 22 (2021), No. 1 (63), 2021

 

This issue of the RECENT journal was edited with the support of:

CONTENTS



  • Maria STOICANESCU, Gheorghe POPA, Marin PETRE, Nicușor Constantin DRĂGHICI

Simulation of Accidental Shutdowns of Thermal Equipment for Artificial Aging Treatment and Their Effect on the Mechanical Properties of 6061 Aluminium Alloy Plates

https://doi.org/10.31926/RECENT.2021.63.004

Abstract

A study on the effects of accidental shutdowns of thermal equipment for artificial aging treatment on the mechanical properties of hot rolled thick plate products of 6xxx alloys was performed. The present study was initiated by performing tests and simulations in the laboratory and continued with the validation in industrial regime on concrete situations of the obtained results. All tests were performed on 6061 aluminium alloy plates, T651 temper. The present study aimed to provide solutions for capitalization, without negative consequences on the quality, of thick plate products made of aluminium alloys, in special cases of accidental shutdown of thermal equipment related to the artificial treatment of artificial aging. A series of solutions are presented for taking the best decision in such possible unwanted situations.

Keywords

aluminium alloy 6061, mechanical properties, artificial aging, T651 temper

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  • Ioan BITIR, Elena Camelia MUSAT, Aurel LUNGULEASA, Valentina Doina CIOBANU

Monitoring the Transport on the Ciobănuș Forest Road within the Bacău Forestry Department

https://doi.org/10.31926/RECENT.2021.63.010

Abstract

Compared to other types of transport, log transport has its own characteristics related to both the transport route and the means of transport. Because, over time, both the routes used to transport timber and the means of transport have constantly evolved, being adapted to the new requirements, specialists in the field always seek to extend the period of operation of forest roads, especially that, in the case of the present, most of them have been designed and built to withstand lower traffic in terms of intensity and frequency. Thus, in order to behave as well as possible in operation, forest roads must be made more precisely the geometric and constructive elements of forest roads and must take into account the constructive characteristics and the movement of vehicles to travel on these roads. Considering the current situation, a very important one, it was considered opportune to research a forest road from the perspective of the traffic on it, recorded for a longer period of time. Thus, the research was carried out on a valley road from the administration of the Bacău Forestry Department - the Ciobănuș forest road. Following the centralization and interpretation of the data, it resulted that the annual distribution of transported volumes is approximately equal and no significant variations were found between 2014 and 2018 and that annually, on the Ciobănuș forest road, a specific tonnage transits the main forest roads, which supports , once again, the accentuated degree of degradation and the rapidity of degradation on this road, due to an insufficiently dimensioned superstructure, which cannot support the annual volumes transited.

Keywords

forest road, traffic monitoring, forest truck, wood mass, log transport

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  • Georgi DINEV, Emilia CHALAKOVA

CAD Geometrical Modelling of Hydraulic Gear Pump and Optimal Structural System for Assembling

https://doi.org/10.31926/RECENT.2021.63.017

Abstract

An approach for design and design documentation of mechanical product in CAD medium is presented. A geometrical modelling of hydraulic gear pump is shown as illustration. On the base of the developed graph model of design elements in assembled unit is generated a 3D geometrical model of mechanical product. A proposal for the use of normative documents: Information system, graph of the links between the design elements and problem related to the planning of material requirements. The Material Requirements Planning (MRP) module enables to plan material requirements for a manufacturing or procurement process based on the re-evaluation of existing inventories, demands, and supplies on changing planning parameters. 3D geometrical models and virtual prototypes of basic and modified variants have been developed. The results show that the most important limitations are minimum price, work area of the automated system as well as the number of operators. The modified variant of hydraulic gear pump has low technological value, high rate of automation and increase productivity. A structural scheme for automated assembling of hydraulic pump by robot from UR3 family is developed. The results will be useful for students, PhD students in Robotic and Mechatronic fields.

Keywords

CAD, modelling, hydraulic, gear, pump, automated, optimal system, assembling, choice, robot

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  • Ioan CIOBANU, Vlad MONESCU

Advantages and Limitations Regarding the Processing of Materials in Concentrated Energy Solar Furnaces

https://doi.org/10.31926/RECENT.2021.63.022

Abstract

Solar energy is already widely used for water heating and electricity production. Attempts to process materials with solar energy have been made since the 17th and18th centuries. The construction of high and medium power concentrated solar furnaces in the late 20th century opened new perspectives in this direction. Lately, the possibilities of processing materials by using this energy are being researched more and more, together with the construction principle and the features of the operation of solar furnace with concentrated energy. Based on the knowledge gained in research conducted worldwide by various authors, including the University of Transilvania in Brasov, an analysis is made of the advantages and limitations of various processing of materials in such ovens, taking into account the possibilities of application at the industrial level.

Keywords

materials processing, concentrated solar energy, solar furnace, surface hardening

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  • Nicoleta RACHIERU

Checking the Performances of Ultrasonic Welding Machines in the Manufacture of Car Wiring

https://doi.org/10.31926/RECENT.2021.63.034

Abstract

An important operation of the technological process of manufacturing the car wiring is the ultrasonic welding operation. This is done with the help of a special machine, equipped with a device on which the parts to be welded are placed. By using a sonotrode, that concentrates the waves, the parts are welded together. The machine is checked periodically to determine whether its performance meets the customer's requirements and whether it should be replaced with a newer model. This paper deals with aspects of ultrasonic welding and its application in the manufacture of automotive wiring, the components of ultrasonic welding equipment and welding parameters. In a case study carried out on a wiring that forms part of a car, the performance of the MINIC II ultrasonic welding machine was checked by the two parameters, the degree of compression and the pulling force. After verification it was found that that a new equipment would lead to the reduction of the number of scraps and, implicitly, to a reduction in manufacturing costs.

Keywords

ultrasonic welding, auto wiring, sonotrode, compression degree

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  • Victoria RUSU, Gavrilă CALEFARIU

Definition and Literature Review on Human Performance Envelope Concept in Aerospace Activity

https://doi.org/10.31926/RECENT.2021.63.041

Abstract

Nowadays, the international aviation organizations are focused on safety improvements, using automation systems and applying ergonomic concepts. One of these concepts is Human Performance Envelope, which is used for pilotís performance determination, based on a set of ergonomic factors. The aim of the paper is to give a clear definition of this concept and to establish what the directions for future studies are. For this reason, was done a literature review of what has been done. It was revealed that workload, stress, situation awareness and attention are the most studied factors, while fatigue, vigilance, teamwork, trust and communication are the least studied. Moreover, all the experiments were done on one member of the crew, so the concept was applied on one person, while in reality the action of the team influences the upcoming events, so the concept should be extended on the team. Also, the proposed solutions regard the cockpit improvement using automation systems, thus none of them concerns the psychosocial aspects. So, the concept of Human Performance Envelope offers great possibilities for future ergonomic studies in aviation.

Keywords

ergonomics, pilots, safety, human performance envelope

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  • Eugen-Silviu VRĂJITORU, Mircea BOȘCOIANU, Elena-Corina BOȘCOIANU

Aligning Complementary Funding Opportunities - through TAS - the Smart Answer to the Challenges of Industry 4.0 Transformation

https://doi.org/10.31926/RECENT.2021.63.050

Abstract

Industry 4.0 transformation is an opportunity that needs to be carefully considered in a different way in emerging markets. The opportunity aims to reduce the gap with developed markets through the link of democratizing the elements of innovation (organizational and transformational technique). Although new funding programs have emerged, accessibility to funding for priority directions and for locations and regions of interest is only slightly related to expectations. Thus, the concept of complementary financing is proposed, and alternative solutions and strategies based on the triple alternative assets - (venture capital and private equity funds), alternative strategies - (hedge funds adapted for emerging markets) and alternative partnerships (public - private partnerships) are identified. The proposed innovative idea is based on capturing the synergies between the three elements of the mentioned triplet and the ability to quickly connect to the financing flow through major programs (NRFF, H2020, NGD). The challenge refers to the reduced functionality of the Romanian capital market, the proposal aiming at practical solutions for creating the adequate complementary financing framework in relation to the real priorities, their dynamics but also the national strategy for reducing local and regional disparities in Romania. The idea is innovative, through modularity and scalability gives real integration capabilities in practice. It also provides an adequate response to the case of low functionality offered by emerging capital markets. In this case the special purpose vehicle SPV is represented by a special dedicated hedge fund with rotating sub-portfolios.

Keywords

complementary funding, Industry 4.0 transformation, venture capital funds VCFs, private equity funds PEFs, hedge funds HFs

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