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Inverse Identification of the Ductile Failure Law for Ti6Al4V Based on Orthogonal Cutting Experimental Outcomes
Get PDFDespite the prevalence of machining, tools and cutting conditions are often chosen based on empirical databases, which are hard to be made, and they are only valid in the range of conditions tested to develop it. Predictive numerical models have thus emerged as a promising approach. To function correctly, they require accurate data related to appropriate material properties (e.g., constitutive models, ductile failure law). Nevertheless, material characterization is usually carried out through thermomechanical tests, under conditions far different from those encountered in machining. In addition, segmented chips observed when cutting titanium alloys make it a challenge to develop an accurate model. At low cutting speeds, chip segmentation is assumed to be due to lack of ductility of the material. In this work, orthogonal cutting tests of Ti6Al4V alloy were carried out, varying the uncut chip thickness from 0.2 to 0.4 mm and the cutting speed from 2.5 to 7.5 m/min. The temperature in the shear zone was measured through infrared measurements with high resolution. It was observed experimentally, and in the FEM, that chip segmentation causes oscillations in the workpiece temperature, chip thickness and cutting forces. Moreover, workpiece temperature and cutting force signals were observed to be in counterphase, which was predicted by the ductile failure model. Oscillation frequency was employed in order to improve the ductile failure law by using inverse simulation, reducing the prediction error of segmentation frequency from more than 100% to an average error lower than 10%
Drilling process monitoring: A framework for data gathering and feature extraction techniques
Get PDFLearnig SCRUM: a POPBL-based experience
Get PDFAgile project management methods have played a prominent role in recent years. Certain aspects as adaptability or orientation toward action characterize agile methods, making them especially interesting in high uncertainty and unpredictability contexts. Thus, some agile methods have transcended the software development context thereby reaching a remarkable expansion in various industries. It is the case of Scrum, which also requires the participants' know-how. In the case of people without a professional background, the starting point is different. Besides, learning agile methods is aimed at application, which requires practice. Lack of experience and fictitious application context hinder this purpose. Consequently, the learning process must overcome these obstacles. This study addresses the abovementioned problem when it comes to learning Scrum through the Project Based Learning approach. Eight teams of students competed to develop the best solution through a project to be managed with Scrum. As a result, we reached interesting findings and conclusions that we believe may be applicable in other methods beyond Scrum.Los métodos ágiles de gestión de proyectos han jugado un papel destacado en los últimos años. Caracterizados por aspectos como la adaptabilidad o la orientación a la acción, son especialmente interesantes en contextos de alta incertidumbre e imprevisibilidad. Así, algunos métodos ágiles han trascendido el contexto original de desarrollo de software, alcanzando una
notable expansión. Es el caso de Scrum, requiere además conocimientos por parte de de los participantes. En el caso de personas sin experiencia, el punto de partida es diferente. Además, el aprendizaje de métodos ágiles tiene como objetivo la aplicabilidad, lo que requiere práctica. La falta de experiencia y la el uso de un contexto de aplicación ficticio dificultan este propósito. En consecuencia, el proceso de aprendizaje debe superar estos obstáculos. Este estudio aborda esta problemática para el caso de Scrum, basándose en un enfoque de aprendizaje basado en proyectos. Ocho equipos de estudiantes compitieron para desarrollar la mejor solución mediante un proyecto gestionado con Scrum. Este trabajo ha dado lugar a hallazgos conclusiones de interés que, además, consideramos que pueden ser aplicables en otros métodos, más allá de Scrum
Adaptable and Explainable Predictive Maintenance: Semi-Supervised Deep Learning for Anomaly Detection and Diagnosis in Press Machine Data
Get PDFPredictive maintenance (PdM) has the potential to reduce industrial costs by anticipating failures and extending the work life of components. Nowadays, factories are monitoring their assets and most collected data belong to correct working conditions. Thereby, semi-supervised data-driven models are relevant to enable PdM application by learning from assets’ data. However, their main challenges for application in industry are achieving high accuracy on anomaly detection, diagnosis of novel failures, and adaptability to changing environmental and operational conditions (EOC). This article aims to tackle these challenges, experimenting with algorithms in press machine data of a production line. Initially, state-of-the-art and classic data-driven anomaly detection model performance is compared, including 2D autoencoder, null-space, principal component analysis (PCA), one-class support vector machines (OC-SVM), and extreme learning machine (ELM) algorithms. Then, diagnosis tools are developed supported on autoencoder’s latent space feature vector, including clustering and projection algorithms to cluster data of synthetic failure types semi-supervised. In addition, explainable artificial intelligence techniques have enabled to track the autoencoder’s loss with input data to detect anomalous signals. Finally, transfer learning is applied to adapt autoencoders to changing EOC data of the same process. The data-driven techniques used in this work can be adapted to address other industrial use cases, helping stakeholders gain trust and thus promote the adoption of data-driven PdM systems in smart factories
Robot-aren itxura estetikoak eta erabiltzaileen preferentziak
Get PDFDatozen urteetan roboten eta pertsonen arteko bizikidetza handitzea espero da, eta ondorioz, beraien arteko interakzioa optimizatzea beharrezkoa izango da. Robotaren itxura estetikoa bere gaitasunen inguruko informazioa jasotzeko modurik ulergarriena da. Robot askok, pertsonekin hobeto interaktuatzeko itxura humanoidea izaten dute, era honetan pertsonen enpatia handitu egiten baita. Hala ere, robot humanoide hauen artean, estetika aldetik bi tendentzia aurki ditzakegu: itxura teknologikoa izaten dutenak eta pertsona itxura erreala dutenak. Pertsonen preferentzia inplizitua zein den jakiteko helburuarekin Asoziazio Inplizituen Testa (IAT) burutu da. Test honek pertsonen preferentziak ezagutzea ahalbidetu du, bai inplizituki eta baita esplizituki ere. Neurketa inplizituaren emaitzan giza itxurarekiko preferentzia nabarmendu da, eta, neurketa esplizituan, aldiz, itxura teknologikoarekiko preferentzia. Emaitzetan lortu den kontraesan honek etorkizuneko ikerketarako ildo interesgarriak azaleratzen ditu.In coming years, the coexistence between robots and humans is expected to increase, and therefore, it will be necessary to optimize human-robot interaction. Robot aesthetics is the most understandable way to display information about a robot's capabilities. Many robots that are intended to interact with people often have humanoid aesthetics, because in this way, they increase people's empathy. However, there are two trends within humanoid aesthetics: those with technological aesthetics and those with real-person aesthetics. In order to find out people's implicit preference, an Implicit Association Test (IAT) has been carried out. This test enabled us to find out people's preferences, both implicitly and explicitly. The implicit measure had shown a preference for the real-person aesthetics, and, on the contrary, the explicit measure had shown a preference for the technological aesthetics. This contradiction in the results indicates an interesting future line for further research
Platform Coops Now!: A Team Entrepreneurship Capacity Building Program to create Platform Coops
Get PDFTraditional labour relationships have been disrupted due to the digital platforms based businesses. This article aims on the one hand to share the consequences the sharing economy has generated for workers, and how MONDRAGON’s principles as one of the best examples of worker owned business group in the world, can be applied within the new digital era. On the other hand, this paper provides a literature review on how digital platforms can operate with fairer principles based on the framework that platform coops consist of. Last but not least, Mondragon University and The New School have set up a capacity building program on team entrepreneurship and an online incubation program that aims to support the creation of platform coops, whose results after two editions and future opportunities for research are shared
Theory of constraints case study in the make to order environment
Get PDFPurpose: The theory of constraints (TOC) drum-buffer-rope methodology is appropriate when managing a production plant in complex environments, such as make-to-order (MTO) scenarios. However, some difficulties have been detected in implementing this methodology in such changing environments. This case study analyses a MTO company to identify the key factors that influence the execution of the third step of TOC. It also aims to evaluate in more depth the research started by Lizarralde et al. (2020) and compare the results with the existing literature.
Design/methodology/approach: The case study approach is selected as a research methodology because of the need to investigate a current phenomenon in a real environment.
Findings: In the case study analysed, the protective capacity of non-bottleneck resources is found to the key factor when subordinating the MTO system to a bottleneck (BN). Furthermore, it coincides with one of the two key factors defined by the literature, namely protective capacity and protective inventory.
Originality/value: The three key contributions of this study focus on the MTO environment as follows.The first is about identifying the key factors in subordinating the system to the BN (step 3, TOC) according to the existing literature which have been identified through a systematic literature review. The second focuses on identifying the key factors in subordinating the system to the BN through a case study. Finally, the last contribution compares the results obtained in the case study with those obtained in the literature review
Ofermod y heroísmo humilde: sobre la interpretación de Tolkien
Get PDFEl presente trabajo estudia la interpretación del heroísmo germano por Tolkien tomando como punto de partida su ensayo-poema «The Homecoming of Beorhtnoth Beorhthelm’s Son» sobre La Batalla de Maldon. A través de textos académicos sobre Beowulf y Sigurd, así como de su propio legendarium, se explora su lectura y contribución, situando su aportación en diálogo con las últimas investigaciones, y detallando las líneas y alcance de sus ideas. Tras situar el punto de inflexión que Tolkien marcó en torno a la palabra ofermod(e), se expondrán los componentes históricos, literarios y religiosos que fundamentan la interpretación de Tolkien, en línea con la tradición poético-heroica anglosajona. Mediante ello, quedará patente que el heroísmo humilde del subordinado que se enfrenta al fatal destino al que su señor le ha conducido hunde sus raíces en claros ejemplos de la literatura en inglés antiguo, y que la oscuridad que acarrea el terrible enemigo posee una dimensión mítica que refiere a la sombra y al infierno. Finalmente, a la luz de las últimas contribuciones, la interpretación de Tolkien quedará reafirmada y enriquecida, dejando nuevas perspectivas de investigación sobre su obra.This paper studies Tolkien’s interpretation of German heroism, taking as a starting point his essay-poem «The Homecoming of Beorhtnoth Beorhthelm’s Son» on The Battle of Maldon. Through academic texts on Beowulf and Sigurd, as well as his own legendarium, his reading and contribution are explored, placing the latter in dialogue with the latest research, and detailing the lines and scope of his ideas. After locating the inflection point that Tolkien marked around the word ofermod(e), the historical, literary and religious com-ponents that base Tolkien’s interpretation will be explained, in line with the Anglo-Saxon poetic and heroic tradition. Through this, it will become clear that the humble heroism of the subordinate who faces the fatal fate to which his master has led him is rooted in clear examples of Old English literature, and that the darkness brought by the terrible enemy has a mythical dimension, which refers to the shadow and to hell. Finally, in light of the latest contributions, Tolkien’s interpretation will be reaffirmed and enriched, opening new research perspectives on his work
Anomaly Detection and Automatic Labeling for Solar Cell Quality Inspection Based on Generative Adversarial Network
Get PDFQuality inspection applications in industry are required to move towards a zero-defect manufacturing scenario, with non-destructive inspection and traceability of 100% of produced parts. Developing robust fault detection and classification models from the start-up of the lines is challenging due to the difficulty in getting enough representative samples of the faulty patterns and the need to manually label them. This work presents a methodology to develop a robust inspection system, targeting these peculiarities, in the context of solar cell manufacturing. The methodology is divided into two phases: In the first phase, an anomaly detection model based on a Generative
Adversarial Network (GAN) is employed. This model enables the detection and localization of anomalous patterns within the solar cells from the beginning, using only non-defective samples for training and without any manual labeling involved. In a second stage, as defective samples arise, the detected anomalies will be used as automatically generated annotations for the supervised training of a Fully Convolutional Network that is capable of detecting multiple types of faults. The experimental results using 1873 Electroluminescence (EL) images of monocrystalline cells show that (a) the anomaly detection scheme can be used to start detecting features with very little available data, (b) the anomaly detection may serve as automatic labeling in order to train a supervised model, and (c) segmentation and classification results of supervised models trained with automatic labels are comparable to the ones obtained from the models trained with manual labels
Design to cost; a framework for large industrial products
Get PDFA literature review on the assembly design methodologies (DfA) oriented to the assembly of large and heavy parts, reveals the need to develop a DfA methodology. In addition, the lack of DfA evaluation methods for on-site assembly is also observed. The most widespread DfA methodologies are more oriented toward the improvement of factory assembly processes, where the assembly processes are well defined and standardised. Hence, this article presents a new methodology for the design of assemblies with large and heavy parts on site, called OSIA (On-Site Installation Analysis). OSIA methodology aims to provide data (indicators). On the one hand the theoretical basis of the OSIA methodology is based on three key concepts: i) analysis of assembly operations similar to the one used by the SMED methodology; ii) generic implementation process of DfA methodologies; and, iii) compilation of assembly operation times and estimation of standard times per operation. On the other hand, the steps in the implementation of the methodology are summarized in: i) database development with assembly operations and standard times; ii) assembly operations analysis; iii) calculation of assembly time; and iv) product optimization. In this way, OSIA methodology supports the designer in the specification phase, detailed design phase and in the redesign processes, providing the designer with indicators that make it possible to optimise the design of the parts and reduce the assembly operations of a product on site