Τμήμα Ηλεκτρολ. Μηχαν. και Τεχνολ. Υπολογιστών (ΜΔΕ)
Permanent URI for this collection
Browse
Recent Submissions
1 - 5 of 160
- ItemOpen AccessRevitalizing the past : a user-centric redesign of an archaeology excavation app(2023-07-29)This thesis conducts a comprehensive analysis on the field of archaeology, exploring its challenges and limitations towards a digital transition. Studies are conducted over a developed poc web application with the functionality to support storing and retrieving archeological logs regarding the artifact findings. These functionalities are continuously used and adjusted to cover and support the collaboration with the archaeologists from the IDIPOS team. Research techniques used in the field of Human-Computer interaction are being applied, reaching for improvements in the user experience and minimizing the gap on the Archeological logging procedures and the optimal user-centric web interface. First part of research conducted within a week period at Prespes lake near Hellenic-Albanian border and part of it using online tools afterwards. Methods at some degree are covered in anarchy but wrap to the following. Direct observation, Interview, Document Analysis are conducted on the field to question whether the application meets the needs of its intended users while interacting directly from the excavation site. Online, a focus group and user story based on the notes provide a collaborative method involving users and stakeholders to define the user's journey in the application. Finally a think aloud study assigns predefined tasks to participants over the old and the new application to then analyze the exported data of the features in question. Overall, the study enables the investigation of whether the application meets the needs of the collaborating archaeological team but also the field as a whole . It engages to communicate flaws on the proposed application and identify areas that may require further refinement. Additionally, the employed user story mapping assists on the development of a minimum viable product (MVP) approach, generating the relevant features to streamline the application development process, making it both cost-effective and efficient. To achieve this objective, the study delves into the design of the user interface (UI) over the proposed application poc, by following a user-centered approach and ensures that the final product has the necessary features and it's easy to use.
- ItemOpen AccessDesign, development and evaluation of a web application that supports a social network for scientific Math-related content(2023-06-29)This dissertation focused on the development and evaluation of MathOverflow, a web-based question and answer (Q&A) app designed specifically for math-related content. The objective of MathOverflow is to create a dedicated platform for students, educators, and math enthusiasts to engage in collaborative problem-solving, knowledge sharing, and community building. The thesis discusses the limitations and potential challenges encountered during the development process and presents the results and methodology of the evaluation. The evaluation, which ensured ecological validity, involved the participation of 100 users who actively utilized MathOverflow in real-world conditions. By engaging participants in their natural environments, the study aimed to capture authentic user experiences and behaviours on the platform. Real data collected during the evaluation allowed for an assessment of the app's effectiveness and usability in practical settings. The findings contribute to the broader understanding of web-based Q&A platforms for mathematical knowledge management and exchange. The statistical analysis revealed a high average SUS score of 81.6250, indicating that participants perceived the system or interface usability as relatively high. Additionally, the chi-square analysis explored the relationship between variables such as voting time, prior experience with Q&A applications, and education level. These findings provide insights into the influence of these variables on user behavior and interaction within the web application. Furthermore, the document presents the architecture of MathOverflow, highlighting the technologies used in its development, and provides an overview of the app's various functions and features. This comprehensive analysis sheds light on the technical aspects of the application's implementation and showcases its capabilities in supporting efficient mathematical collaboration and problem-solving.
- ItemOpen AccessOnline platform to support victims of natural disasters(2023-06-28)This thesis presents the development and evaluation of an online platform aimed at providing support to individuals affected by natural disasters. Through a user-centered design approach, the platform addresses common challenges faced by victims during the post-disaster recovery phase. The platform offers a centralized information hub, real-time updates on relief efforts, and a community support system. The platform was developed through sequential phases starting with requirement analysis followed by interface design, evaluations and concluding with code development. The structure of the thesis consists of the following chapters and sections: Chapter 1: Introduction Subject analysis and purpose of the thesis are presented providing an overview of the research objectives and scope. Chapter 2: Analysis of Application’s Requirements and Specifications Focus on the analysis, starting with personas representing different user roles such as victims of natural disasters, organization employees, and volunteers. Storyboards illustrating on-site and application scenarios are included. Use case scenarios for employees, volunteers, and victims are also explored. Chapter 3: Database Design Database design, including the procedure of creation of the database and analysis of its structure. Chapter 4: Design of the Application's Interface Interface design aspects, beginning with a hierarchical task analysis (HTA) and its description. A site map is presented to provide an overview of the application's structure. Chapter 5: Initial Designs Initial designs of the web application, including the general structure of the application. The specific pages of the application are, also presented. Chapter 6: Evaluations & Redesigns Various evaluation methods, including heuristic evaluation, think-aloud evaluation, and questionnaires, to assess the usability and user experience of the application. Based on theses evaluation results, redesigns are proposed. Chapter 7: Technologies Used Overview of the technologies used in the design and development of the application. Front-end, database, back-end, and hosting aspects. Chapter 8: Conclusion and Future Work Summary of the findings and conclusions of the thesis. Potential future work and roll out of the application. Annexes Parts of the source code that was implemented in order to develop the web application. Usability testing and user feedback demonstrate positive experiences and increased feelings of support and resilience. The thesis contributes to the field by providing an innovative solution to enhance post-disaster support and inform future research in disaster management.
- ItemOpen AccessUncovering themes and trends in HCI(2023-06-28)This thesis aims to identify the trends in the field of Human Computer Interaction. In the context of this work, a python tool was developed which, through the search for keywords and the number of their occurrences, in publications of selected sessions per year, receives as input the pdf files with the publications of each conference that we wish to evaluate, processes them by isolating the words we are looking for and then records the number of their occurrences in each year for the conference we are looking at. The data from this processing are exported, for their better management, to an Excel and then with the help of SPSS we proceed to evaluate them and extract the results to identify trends that will concern us in the future years in the field of HCI or even topics that are on the decline in the industry and we won't need to waste resources investigating them.
- ItemOpen AccessEffect of printing parameters on the mechanical properties of 3D-printed specimen(2023-06-28)3D printing is an ever-growing manufacturing process, gaining a lot of popularity in the last years, with potential for application in a multitude of fields, particularly in the medical field on the subject of prosthetics and orthotics. Its ease of accessibility and both time and cost effectiveness make it an attractive alternative to current manufacturing processes. Due to its recency, however, as well as insufficient documentation for the thermoplastic materials it commonly uses (compared to more conventional materials like metals), there is an information gap, regarding how the plethora of pre-process configurations and parameters can potentially affect the mechanical properties of the 3D-printed parts. The goal of this thesis is to fill this gap, as well as provide a guideline for future studies regarding this subject. To achieve this goal, a number of specimen was printed, following the guidelines from ASTM D638 standard, which would be tested for their tensile properties. The standard procedure is to input the CAD file of the specimen into the slicer program of the 3D printer, and after some configurations, an STL file is exported, which can be read by the 3D printer, and the part is produced. These configurations have to do with the 3D printing procedure, from nozzle temperatures to specific instructions on how the printer will fill the volume of the part. The latter is very important, as it creates an internal geometry, which greatly affects the mechanical behavior and load response of the 3D printed part, and this is what is tested in this thesis. To do that, control specimen were created, with specific values for four printing parameters that were to be tested: Infill Density, Perimeter Thickness, Shell Thickness and Layer Height. The rest of the specimen had the value of one parameter changed, while the rest remained as they were, in order to test the effect of each parameter individually. For the creation of the specimen, four common 3D-printing materials (PLA, PETG, CPE and ABS) were used, to determine the potential effect that the parameters had on each one. The specimen were then tested on a tensile testing apparatus, to determine their tensile properties, and more specifically, Modulus of Elasticity and Tensile Strength, and compared to determine their differences, taking into consideration the printing time and the cost of their manufacturing. This indicated the effectiveness of each parameter and whether applying that change would be worthwhile, which is especially useful information in large scale operations. The tensile tests showed that perimeter thickness had the greatest effect on the mechanical properties on the specimen, regardless of the material used, and that by increasing it, both modulus of elasticity and tensile strength would improve significantly, with minimal change in printing time and cost. Shell thickness came second on this matter, also having a noticeable effect on the mechanical properties of the specimen. Increasing the infill density did increase the modulus of elasticity for the specimen, but had a small effect on the tensile strength. In addition, these improvements came with a substantial increase in both printing time and cost, making other adjustments, like the ones mentioned above, more attractive. Finally, in all cases, layer height had a small effect on both modulus of elasticity and tensile strength, compared to the other parameters, while increasing printing time drastically, making it a suboptimal choice, and thus not recommended for improving the mechanical properties of a part, unless required by its geometry. To validate these experimental results, a Finite Element Analysis model of the tensile specimen was created, which was used in a simulation tensile test. At first, a CAD model of the 3D-printed part, which included the internal geometry, was created in Autodesk Fusion 360, and was then imported in ANSYS Mechanical Student ver., the software used for the simulations. Since ANSYS does not have material data for plastics, they were created from scratch for each material used. With the creation for the materials done, a mesh was then constructed for the specimen, which essentially breaks the model into Finite Elements, to be used in the analysis. Finally, boundary conditions and loads that replicated the tensile tests were configured, the simulation setup was ready. Same simulations were run multiple times with increasing number of FE used, to reach mesh convergence, and the converged data was used to extract the information required (tensile strength and modulus of elasticity), to be compared with the experimental results. Unfortunately, it should be kept in mind that factors like FE usage license limitations, as well as material data inaccuracies by manufacturers and difficulty in finding appropriate material models to express the mechanical behavior of plastics in ANSYS have lowered the quality of the simulation model and its results. The simulated tensile tests’ results were overall close to their experimental counterparts, indicating that the model was accurate, but lacked precision. There were only a few exceptions, regarding the tensile strength of the specimen, where the model was not able to accurately predict the specimen’s tensile behavior. In addition, the simulation model was more accurate predicting the behavior of PETG and CPE than ABS and especially PLA, which showed larger differences between results. In the end, however, this model was able to predict up to a point, the mechanical properties of 3D-printed specimen, thus validating the experimental results. Narrow time margins prevented the further improvement of the FEA model. Testing the simulation model without license limitations, as well as a more refined material model would be some basic directions for further research on the FEA part. As far as the experiments go, more parameters like printing orientation and infill patterns, as well as other mechanical tests, like fatigue and compression, would expand the scope of this study and are necessary, in order to have a clearer picture on 3D-printing as a whole.