Athens Journal of Τechnology & Engineering最新文献

{"title":"The UPMQube: An Academic/Educational PocketQube Proposal for the EU2Space Challenge","authors":"E. Roibás-Millán, José Miguel Álvarez-Romero, S. Marín-Coca, Pza. Cardenal Cisneros, Madrid, Spain, J. Pérez-Álvarez, J. Cubas, S. Pindado, E. Roibás-Millán","doi":"10.30958/ajte.10-1-2","DOIUrl":"https://doi.org/10.30958/ajte.10-1-2","url":null,"abstract":"In the present paper, the UPMQube PocketQube proposal for the EU2Space challenge is described. This proposal has been developed by a group of master’s degree students led by Ph.D. students and professors from the Instituto Universitario de Microgravedad “Ignacio Da Riva” (IDR/UPM) at Universidad Politécnica de Madrid (UPM). PocketQube is a recent new picosatellite concept, which is currently under development. Its reduced size and mass require a significant effort to reduce the characteristic size of the elementary subsystems. One of the subsystems that offers the greatest capacity for improvement is the Attitude Determination and Control Subsystem (ADCS), since most PocketQubes do not usually have one due to lack of space. The most relevant technical aspect of this proposal is the development of a new ADCS which fits the high restrictive size and mass requirements, and it is based on Commercial Off-The-Shelf (COTS) components. This ADCS is composed by: (i) a purely Autonomous Magnetic Controller (AMC) based on magnetorquers and magnetometers on board the spacecraft (S/C platform; (ii) an Attitude Determination System (ADS) based on solar sensors and thermal sensors on board the S/C and an On Ground Attitude Determination Algorithm (for post processing the sensors flight data. The work carried out by Master s degree students is integrated within the academic program of the UPM’s Master in Space Systems as a Case of Study. It also provides an excellent training program for the Ph.D. Assistant Professors included in the proposals Team. The tasks assignments and responsibilities of all members of the Team are fully described in the paper. Additionally, it should be underlined that this proposal is quite well balanced in terms of gender, as 40% of the Team (including the Principal Investigator) are women. This figure is higher than the mean percentage of women present in STEAM Sciences, Technology, Engineering, and Mathematics careers (29% of the workforce, 19% of company board members, 3% industry CEOs). Keywords: UPMQube, PocketQube, MUSE, magnetic ADCS, space engineering challenge","PeriodicalId":197899,"journal":{"name":"Athens Journal of Τechnology & Engineering","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124776158","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluation of the 3D Reconstruction Performance of Objects in Meshroom: A Case Study","authors":"I. Enesi, A. Kuqi","doi":"10.30958/ajte.10-1-3","DOIUrl":"https://doi.org/10.30958/ajte.10-1-3","url":null,"abstract":"3D reconstruction of objects is with interest nowadays, mainly in production industry. The field of photogrammetry realizes the 3D reconstruction of objects through 2D photos. Different software, free or non-free exist, providing different quality and performance. Accurate 3D reconstruction is important in cloning objects, especially in the industry of spare parts or in the production of prostheses in medicine, etc. Determining accurately the sizes of the object, especially those with complex geometric shapes is very important in the 3D printing process. The purpose of this paper is the analysis of the accuracy of 3D reconstruction of objects against the number of its photos and the time evaluation of this process. The 3D reconstruction will be performed by free Meshroom software, measurement will be done in MeshLab one. Experimental results show that quality and performance of 3D reconstruction depends on the number of photos of the object, concluding in finding the optimal balance between these parameters. Keywords: Meshroom, MeshLab, 3D reconstruction, sizes accuracy, time analysis","PeriodicalId":197899,"journal":{"name":"Athens Journal of Τechnology & Engineering","volume":"24 8","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132149373","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Machine Learning Solutions in Combating COVID-19: State of the Art and Challenges","authors":"Muhammad Bin Abubakr Joolfoo, Mussawir Ahmad Hosany","doi":"10.30958/ajte.10-1-4","DOIUrl":"https://doi.org/10.30958/ajte.10-1-4","url":null,"abstract":"COVID-19 is a toxic virus that emerged in China and caused an epidemic globally. COVID-19 virus patients are placed in isolation so that the virus does not blow out widely. The only approach to secure people from this deadly virus is by maintaining social distance among people, wearing gloves and masks, and sanitizing and washing hands regularly. The law enforcement agencies and Government are included in prohibiting people movement in varied cities to control the virus spread. It is not feasible for government to supervise all places namely hospitals, shopping malls, banks, government offices and direct people to following the safety guidelines prescribed by government. The COVID-19 virus has been spreading in a drastic way with the feasibility of a restricted amount of testing kits rapidly. Therefore, the diagnosis of COVID-19 model is important to recognize the occurrence of disease from radiological images. The major aim of the research is to review different machine learning solutions in combating COVID-19. Various machine learning models are implemented to combat COVID-19 virus. The proposed models with the along computer vision algorithm are used as a corresponding device to be fixed at varied places and supervise people to adopt secure guidelines which are suggested by the government. By following the precautionary steps and using the solutions of machine learning, people are capable to succeed with the fight against COVID-19 virus. Keywords: COVID-19, machine learning, social distancing, face mask, hand hygiene, deep learning","PeriodicalId":197899,"journal":{"name":"Athens Journal of Τechnology & Engineering","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127868438","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dependency Visualization Tool for Decision Support Systems with Preferential Dependencies","authors":"S. Samaranayake, Shehan Senanayake","doi":"10.30958/ajte.9-4-1","DOIUrl":"https://doi.org/10.30958/ajte.9-4-1","url":null,"abstract":"Large-scale and long-term projects often consist of subtasks linked to each other with certain dependencies that need to be completed. Dependency evaluation and visualization tools can help identify project bottlenecks, prioritize tasks, and plan resource allocation. Hence, visualization tools can improve the efficiency of project interdependency management by dynamically displaying the project constraints and task dependencies. Many of the dependency visualization tools that are being used in the industry are designed to manage internal dependencies and task dependencies. In this work, we introduce an online tool for creating and maintaining visualizations of logical dependencies and preferential dependencies. The proposed online tool can be used with any process that is defined in terms of completing a well-defined logical sequence of activities that must be completed in order to reach a specific target, such as project planning, or with any process that can be completed by different sequences of activities, such as college degree planning (due to elective courses) or interest-aligned career planning. Keywords: academic decision making, decision support system, data visualization, dependency visualization, project management","PeriodicalId":197899,"journal":{"name":"Athens Journal of Τechnology & Engineering","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131120428","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Environmentally Friendly Building Materials with Beneficial Potential for Indoor Air Quality","authors":"Gabriela Adela Călătan, C. Dico","doi":"10.30958/ajte.9-4-3","DOIUrl":"https://doi.org/10.30958/ajte.9-4-3","url":null,"abstract":"Following the obvious increasingly interest for environmental protection and pollution reduction, worldwide, there is a strong orientation for identification and use in buildings some materials that require low power consumption and to determine a pollution low level in all stages of their production and exploitation. These energy and environmental protection criteria can be met successfully by a combination of unburned masonry bodies made of clay, mixed with various other natural materials, and sheep wool thermal insulation mattresses. These construction elements have a beneficial influence on the air quality of the interior space, ensuring, through the permeability to water vapor, the regulation of the relative humidity of the air and, through ability to store thermal energy in warm periods and release it in the cold ones, a uniform temperature distribution inside and avoiding high temperature fluctuations between seasons. Based on the experimental research results, we can identify solutions for achieving a vernacular housing (resistance walls, partition walls, floors, plasters, water protection, thermal insulation and finishing) in terms of safety, comfort and current aesthetic criteria. Keywords: adobe bricks, clay, hemp fibers, straw, sheep wool","PeriodicalId":197899,"journal":{"name":"Athens Journal of Τechnology & Engineering","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121273156","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical Estimation of a Mode III Fracture Mechanics Parameter for a Three-Dimensional V-Notch on a Steel Bold","authors":"M. Elliotis","doi":"10.30958/ajte.9-4-2","DOIUrl":"https://doi.org/10.30958/ajte.9-4-2","url":null,"abstract":"In this work a couple of three-dimensional problems in the domain of linear elastic Fracture Mechanics are examined. These are problems of solid bodies (they could be steel bolds or rivets) with a surface crack singularity (V-notch). They are reduced to Laplace equation problems by considering a Lamé potential. The boundary singularity is numerically treated as per the singular function boundary integral method (SFBIM), which in the literature is known as one of the so-called Trefftz methods. Thus, the general solution of the governing equation, in the vicinity of the surface crack, is expressed as an asymptotic expansion, the coefficients of which are approximated by polynomials. The remaining numerical steps are followed according to this method with which very fast convergence and very high accuracy are observed. In fact, the CPU time and the numerical error recorded with this numerical technique are significantly smaller than those achieved with the finite element method (FEM) which was also used to solve the same problems. The calculated value of Mode III Fracture Mechanics parameter (FMP) indicates that there is no danger of crack propagation. Thus, the extension of the method to this category of problems is considered as a novel application of this algorithm in Fracture Mechanics. Keywords: Mode III Fracture Mechanics parameter, crack singularity, governing equation, singular","PeriodicalId":197899,"journal":{"name":"Athens Journal of Τechnology & Engineering","volume":"18 7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127115239","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Measuring the Level of Technology in Moral Economics","authors":"Zsófia Hajnal","doi":"10.30958/ajte.9-4-4","DOIUrl":"https://doi.org/10.30958/ajte.9-4-4","url":null,"abstract":"This theory-based paper attempts classifying and combining methods of orthodox and heterodox economics regarding the measurement of technology levels. The importance of measuring the level of technology is illustrated by technology being a key factor in several neoclassical models. However, just as for the concept of utility, traditional economics treats the level of technology as an abstract scientific construct, without attempts for an absolute quantification. This paper argues that through a systematic classification and various methods, starting- and end points, milestones and even units can be determined. Through surveying the literature, the paper identifies the existing options of measurement, and their shortcomings. Technology is looked at as a “stock”, as opposed to the overrepresented “flow” nature. This gives space for the methods of constructing an absolute scale, and for the unique concept of the “steady-state technology”. Distinctions are made between demand-side and supply-side measurement, as well as between historical and geometrical methods of constructing scales. The methods are illustrated, though not fully implemented, due to limitations in scale and scope. Finally, the paper shows how heterodox economic branches, such as the newly emerging moral economic school, allow for the demand-side measurement to a greater extent, given the adjusted economic axioms. Keywords: technology, demand side, historical method, geometrical method, moral economics","PeriodicalId":197899,"journal":{"name":"Athens Journal of Τechnology & Engineering","volume":"239 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114146091","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Interaction of Wind Velocity and Air Gap Width on the Thermal Comfort in Naturally Ventilated Buildings with Multiple Skin Facade","authors":"Enes Yasa","doi":"10.30958/ajte.9-3-4","DOIUrl":"https://doi.org/10.30958/ajte.9-3-4","url":null,"abstract":"A Multiple (MSF) or Double Skin Facade (DSF) is a building envelope system. It has an external and internal layer that contains buffer space used for controlled windy conditions, ventilation and solar protection. Employing a multiple or double-skin facade for natural ventilation is not an innovative idea, but the background on this mechanism and the impacts of these environmental and designing factors on its performance are still unknown and critically needed. Therefore, with this study, the influences of the Multiple or Double Skin Facade with different width air gaps configurations, alongside the environmental factor on buoyant-driven natural ventilation, are discussed. Naturally ventilated MSFs are often very intriguing in terms of a microclimatic comfort, but an optimum design is crucial to enhance the microclimatic comfort and therefore the proper operation of the entire system. Especially, the development of the system is important when working in a hot climate. There is a significant lack of data within the current literature to demonstrate the complexity and challenges in designing large, naturally ventilated buildings. For these sorts of buildings, it is important to possess the tools to gauge a design’s predicted performance to realize successful natural ventilation concepts. However, with the utilization of glass, heat loss during the winter and solar gain during the summer will increase energy loads. At the same time, this will also negatively effect the microclimatic comfort. Through this study, both the effect of the utilization of multiple facades on indoor comfort conditions and thus the effects of distances at different distances from the facade on wind flow and therefore microclimatic comfort at the situation of the Multiple Skin Facades were investigated. This paper demonstrates through a sensitivity analysis, an optimal strategy for completing a CFD simulation of this special building envelope. This study also attempts to research a mechanically ventilated building with DSF configuration—a building in terms of indoor microclimatic thermal comfort. The aim of this study is to work out the effect of wind velocity and wind distribution on naturally ventilated buildings with DSF configuration, to work out if a DSF configuration will provide a far better microclimatic thermal comfort through natural ventilation. This study not only defines and analyzes the dimensional parameters of the air gap to maximize airflows, but also explores the importance of design decisions on system performance, such as the interaction between thermal mass and air gap distances and the building facade. Keywords: double skin facade, microclimatic thermal performance, airflow modelling, ındoor microclimatic thermal comfort, wind velocity, wind distribution, CFD, natural ventilation performance simulation","PeriodicalId":197899,"journal":{"name":"Athens Journal of Τechnology & Engineering","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125239653","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Examining Student Support in Implementing Open Distance Learning during COVID-19","authors":"S. Makgopa","doi":"10.30958/ajte.9-3-2","DOIUrl":"https://doi.org/10.30958/ajte.9-3-2","url":null,"abstract":"In times of crisis and the global spread of the COVID-19 pandemic, the world has observed exponential growth of online education as educators and students are required to stay at home and resume with online learning entirely. With the new norms in education, come new experiences and challenges. The demands in online learning have pushed both students and educators to maximise their information communication technology (ICT) skills and caused some to be unwillingly ready for the new normal. The purpose of this study is to describe the student support of registered students in open distance learning (ODL) institutions during the COVID-19 era. Active learning theory is adopted as a theoretical lens for the interpretation of the data. This study used a quantitative research method approach to gather insights regarding the student experience pertaining to technology integration in the ODL context during COVID-19. The findings uncovered challenges associated with online student support in ODL context. This paper provide recommendations to key stakeholders in higher learning institutions and future research directions. Keywords: active learning theory, COVID-19, information communication technology, open distance learning, student support","PeriodicalId":197899,"journal":{"name":"Athens Journal of Τechnology & Engineering","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124988650","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Preload Stability of Modern Bolted Joints","authors":"T. Held, Jens Peth, C. Friedrich","doi":"10.30958/ajte.9-3-3","DOIUrl":"https://doi.org/10.30958/ajte.9-3-3","url":null,"abstract":"The design of screw joints is very important for fastened components to ensure reliable transmission of mechanical or thermal loads between components. Suitable fastener selection and proper design are required for increasing product performance while reducing size, weight and cost ratios. A fastening system is basically characterized by component geometry, materials and tightening level. Robust clamping of components depends on time dependent clamp force, which can be represented by Bolt’s preload change. In any fastening system preload loss takes place. The contribution shows, why (seating, load plastification, creeping). Furthermore, the loss may not be too large to provide suitable behaviour over time. This means, a higher tightening preload cannot be utilized, if most of the advantage is compensated by preload loss. Important influences are clamped materials, tightening level (from assembly method) and type of thread engagement. For various combinations long time measurements of preload loss over time are shown. The paper shows also how the measurement is done. The outcome of all the combinations is that preload loss significantly exceeds the estimations of existing guidelines, e.g., VDI 2230. The reason is, that in time of development of the guidelines mainly steel components have been used and preloading was moderate. So the conclusion is to extend the calculation with a better and more flexible approach for today´s requirements. Overall, the contribution combines explaining mechanisms for preload loss, results from measurements for analysis as well as calculation for prediction in advance to extend guidelines.","PeriodicalId":197899,"journal":{"name":"Athens Journal of Τechnology & Engineering","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127761221","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}