European Journal of Engineering Science and Technology <p>European Journal of Engineering Science and Technology (EJEST) is a peer-reviewed, open-access journal that provides rapid publication of articles in all areas of Engineering Science and Technology. EJEST is an international, scholarly and peer-reviewed journal (online) published semiannually by Diamond Scientific Publication.</p> Mokslinės Leidybos Deimantas (Diamond Scientific Publication) en-US European Journal of Engineering Science and Technology 2538-9181 Simulation Modeling for Earth to Air Heat Exchanger system by Using MATLAB <p>A MATLAB model was built for the preparation of initial designs for the establishment of an EAHE system for the purpose of heating and cooling buildings. The purpose of creating this model is to save time and effort by creating a new model capable of providing us and specialized designers with initial perceptions of the size of the appropriate system for the functional requirements for the purpose of cooling and heating buildings. A parametric analysis was then performed to evaluate and investigate the factors affecting the efficiency of the EAHE system. It was found that the pipe diameter is directly proportional to the pipe length, and inversely to the airflow velocity, pressure losses, and AFP. Airflow velocity reduced from 77.05 m/s to 0.1926 m/s, and AFP decreased from 9223 W to 0.058 W when diameter increased from 0.1 m to 2 m. The inlet air temperature affects the length of the pipe in four phases, it is inversely proportional in the first and third phases and directly in the second and fourth phases. These phases depend on the values of soil, inlet, and outlet temperature. This paper presents new equations to determine these phases to determine excluded range which is recommended should not use an inlet air temperature value through this range. The pipe number is directly proportional to pipe length. Pipe length increased&nbsp;from&nbsp;57.16 m to 344.9 m when the pipe number increased from 1 to 10 pipes. The number of pipes has no influence on the overall airflow velocity or total heat transfer. The length of the pipe is directly proportional to the soil temperature in the first and third phases and inversely proportional in the second and fourth phases. Designers could get an idea of this range by utilizing the equations presented in this paper. There is no direct effect between the soil temperature and power, but rather it affects it through the length of the pipe, as it is directly proportional to pipe length.</p> Mohammed H. Ali Zoltan Kurjak Janos Beke Copyright (c) 2022 European Journal of Engineering Science and Technology 2022-03-27 2022-03-27 5 1 1 19 10.33422/ejest.v5i1.843 Investigation of the effect of different factors on the performance of several perovskite solar cells: a simulation study by SCAPS <p><em>The new generation of solar cells based on perovskite materials has attracted&nbsp; massive attention from the photovoltaic community, due to their high capability in supporting low-cost solar cell. In this study, extensive theoretical research of three types of lead-based&nbsp; (MAPbI<sub>3</sub>, FAPbI<sub>3</sub> and CsPbI<sub>3</sub>)&nbsp;and four types of lead-free (MASnI<sub>3</sub>, FASnI<sub>3</sub>, CsGeI<sub>3</sub>, and MAGeI<sub>3</sub>) perovskite solar cells are modeled while Cu<sub>2</sub>O is used as HTL and TiO<sub>2</sub> as ETL. The initial results show commendable performance for MAPbI<sub>3</sub> with 24,8% efficiency, while MAGeI<sub>3</sub> has the lowest performance (12,61%). In addition, different factors reviewed affect the performance almost similarly to the studied types of perovskites. </em></p> Hasan MallaHasan Özlem Onay Copyright (c) 2022 European Journal of Engineering Science and Technology 2022-04-20 2022-04-20 5 1 20 38 10.33422/ejest.v5i1.927 The Role of FabLabs on Footwear and Metal Sectors: Prospects, Challenges, and Recent Applications <p class="TTPAbstract" style="margin: 0cm; text-indent: 0cm; line-height: 150%;"><span lang="EN-US">This paper presents the role of FabLabs in the Portuguese footwear and metal industrial sectors, regarding the use of new and disruptive technologies and processes at industrial scale, aiming for the digitalization of the industry. MetalShoe FabLab Network is a project intending to provide a physical space and, at the same time, offering knowledge for experimentation, demonstration, validation, and human resources training regarding digital manufacturing technologies, with focus in the industrial implementation. For that, a survey was conducted among industrials from both sectors to understand the needs and expectations regarding these types of technologies. Digitalization, automation and robotics, additive manufacturing and digital marketing were the ones selected as the technologies not yet integrated and that would bring value to the companies, while the companies want to learn more about digitalization, additive manufacturing &amp; 3D Printing and IoT, these being similarly chosen, and automation and robotics following closely behind. In this sense, the outputs of the projects were technical referential about each technology, guides for applications of the technologies, workshops, technical sessions and demonstration actions. In the end, it is expected that Portuguese companies from both sectors would recognize the potential of digital manufacturing technologies and incorporate those that provide the most value to each entity.</span></p> <p>&nbsp;</p> Maria Goreti Fernandes Pedro Duarte Cristiano Figueiredo Carla Florbela da Silva Vânia Pacheco Cristina Marques Copyright (c) 2023 European Journal of Engineering Science and Technology 2022-06-25 2022-06-25 5 1 39 52 10.33422/ejest.v5i1.965 Evaluation of Embroidery Defects and Solution Proposals in Clothing Sector <p>Nowadays, it has become more important to follow the latest developments concerning the clothing sector as staying up to date is likely to help us eliminate unnecessary expenditures and increase productivity. In order for companies to continue and expand their activities in ever-changing market conditions compared to their competitors, they need to make their own enterprises compatible with this emerging technology as much as possible by following the developing technology. In this study, the embroidery department of an exporting company was examined. More specifically, the embroidered products were carefully checked and faulty pieces were separated and classified according to the types of defects. The most critical defects were determined by means of Pareto analysis according to defect types and frequencies and an auxiliary apparatus was placed on the embroidery machine to prevent the defect in question. After the placement of the apparatus, the products were checked again. As a result of the calculations, the percentage of the defects in question decreased from 42.41% to 4.6%, and an improvement of 37.81% was achieved with the apparatus developed within the scope of this study.</p> Mehmet KUCUK Şafak Birol Copyright (c) 2023 European Journal of Engineering Science and Technology 2022-06-20 2022-06-20 5 1 53 62 10.33422/ejest.v5i1.979