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Review of computational parameter estimation methods for electrochemical models
Full text linkElectrochemical models are an incipient technique for estimation of battery cells internal variables, useful for cells design or state of function optimization. One of the non-trivial procedures that allow the use of this type of models is the estimation of model parameter values. This paper presents a review of the existing computational parameter estimation methods for rocking chair batteries electrochemical models, a crucial step for real case implementation. Physics-based models cannot reach accurate predictions if the parameters are not properly estimated, what highlights the necessity of reviewing the validity of these protocols, that are not extensively treated within literature. The gathered methods are explained and analyzed taking into account the accuracy and extent of the presented results, to give the most objective overview of their applicability within real case scenarios. The methods are classified into two different groups: single optimization analysis (using only one optimization procedure to estimate parameters) and multiple optimization analysis (methods using multiple optimizations). In addition, the need for at least some amount of physico-chemical characterization is analyzed as a common procedure for all the parameter estimation methods. The accuracy of each method is determined, taking as reference the best achievements found in literature. The results show that it is possible to estimate parameters with a high accuracy using non-invasive parameter estimation methods. Finally the potential of mixed (non invasive and physico-chemical based) methodologies is presented. These type of estimation procedures can potentially increase the accuracy of the procedures by lightening up the optimizations involved in the processes, and increasing the ability to estimate values for insensitive parameters. These mixed methods could achieve faster and cheaper estimation protocols, making them more efficient in general
¡Hola! Nice to Meet You: Language Mixing and Biographical Information Processing
Full text linkIn bilingual communities, social interactions take place in both single- and mixed-language contexts. Some of the information shared in multilingual conversations, such as interlocutors’ personal information, is often required in consequent social encounters. In this study, we explored whether the autobiographical information provided in a single-language context is better remembered than in an equivalent mixed-language situation. More than 400 Basque-Spanish bilingual (pre) teenagers were presented with new persons who introduced themselves by either using only Spanish or only Basque, or by inter-sententially mixing both languages. Different memory measures were collected immediately after the initial exposure to the new pieces of information (immediate recall and recognition) and on the day after (delayed recall and recognition). In none of the time points was the information provided in a mixed-language fashion worse remembered than that provided in a strict one-language context. Interestingly, the variability across participants in their sociodemographic and linguistic variables had a negligible impact on the effects. These results are discussed considering their social and educational implications for bilingual communities
A novel machine learning‐based methodology for tool wear prediction using acoustic emission signals
Full text linkThere is an increasing trend in the industry of knowing in real-time the condition of their assets. In particular, tool wear is a critical aspect, which requires real-time monitoring to reduce costs and scrap in machining processes. Traditionally, for the purpose of predicting tool wear conditions in machining, mathematical models have been developed to extract the information from the signal of sensors attached to the machines. To reduce the complexity of developing physical models, where an in-depth knowledge of the system being modelled is required, the current trend is to use machine-learning (ML) models based on data from the tool wear. The acoustic emission (AE) technique has been widely used to capture data from and understand the real-time condition of industrial assets such as cutting tools. However, AE signal interpretation and processing is rather complex. One of the most common features extracted from AE signals to predict the tool wear is the counts parameter, defined as the number of times that the amplitude of the signal exceeds a predefined threshold. A recurrent problem of this feature is to define the adequate threshold to obtain consistent wear prediction. Additionally, AE signal bandwidth is rather wide, and the selection of the optimum frequencies band for feature extraction has been pointed out as critical and complex by many authors. To overcome these problems, this paper proposes a methodology that applies multi-threshold count feature extraction at multiresolution level using wavelet packet transform, which extracts a redundant and non-optimal feature map from the AE signal. Next, recursive feature elimination is performed to reduce and optimize the vast number of predicting features generated in the previous step, and random forests regression provides the estimated tool wear. The methodology presented was tested using data captured when turning 19NiMoCr6 steel under pre-established cutting conditions. The results obtained were compared with several ML algorithms such as k-nearest neighbors, support vector machines, artificial neural networks and decision trees. Experimental results show that the proposed method can reduce the predicted root mean squared error by 36.53%
Análisis de las creencias sobre la concepción de la educación física de los futuros docentes durante la formación universitaria
Full text linkEl objetivo de este estudio consiste en analizar cómo influyen las creencias previas sobre la Educación Física en los futuros docentes de esa área. Así mismo, se pretende valorar en qué medida la formación universitaria puede modificar esas creencias. En el estudio participaron 827 alumnos/as (407 chicos y 420 chicas; edad: 18-26) de los Grados de: Educación Primaria, Educación Infantil, Ciencias de la Actividad Física y del Deporte, y Ciclo Medio de Animación de Actividades Físicas y Deportivas. Se midieron las creencias en torno a la Educación Física que poseía, por un lado, el alumnado que se iniciaba esos estudios; y por otro, el que lo finalizaba. Se empleó el cuestionario Feelings about Physical Education (Bourke & Frampton, 1992). Se analizó si existen diferencias en las creencias dependiendo de diversas variables: las motivaciones, el género, la formación anterior, la experiencia en el deporte escolar y el deporte federado, y la práctica deportiva. Entre los resultados destaca: que se distinguen dos perfiles diferenciados dentro del alumnado; que las creencias varían sobre todo dependiendo de la titulación universitaria que están cursando; y que la experiencia previa en el ámbito deportivo es la siguiente variable más significativa; lo que invita a la reflexión en torno a los planes de estudio y el perfil de ingreso.The objective of this study is to analyse how previous beliefs about Physical
Education influence future teachers in that area. Likewise, it intends to assess to what
extent university education can modify these beliefs. 827 students participated in the
study (407 boys and 420 girls; age: 18-26) from the Degrees: Primary Education, Early
Childhood Education, Physical Activity and Sports Sciences, and The Medium Cycle
of Animation of Physical Activities and Sports. Beliefs around Physical Education
possessed, on the one hand, by the students who started those studies were
measured and on the other, the ones who finished it. The Feelings about Physical
Education questionnaire (Bourke & Frampton, 1992) was used. It was analysed
whether there are differences in beliefs depending on various variables: motivations,
gender, previous training, experience in school sports and federated sports, and
sports practice. Among the results, it stands out: that two different profiles are
distinguished within the student body; that beliefs vary especially depending on the
university degree they are pursuing; and that previous experience in the sports field
is the next most significant variable; which invites reflection on the study plans and
the entry profile
Modeling of Drag Finishing: Influence of Abrasive Media Shape
Full text linkDrag finishing is a widely used superfinishing technique in the industry to polish parts under the action of abrasive media combined with an active surrounding liquid. However, the understanding of this process is not complete. It is known that pyramidal abrasive media are more prone to rapidly improving the surface roughness compared to spherical ones. Thus, this paper aims to model how the shape of abrasive media (spherical vs. pyramidal) influences the material removal mechanisms at the interface. An Arbitrary Lagrangian–Eulerian model of drag finishing is proposed with the purpose of estimating the mechanical loadings (normal stress, shear stress) induced by both abrasive media at the interface. The rheological behavior of both abrasive slurries (media and liquid) has been characterized by means of a Casagrande direct shear test. In parallel, experimental drag finishing tests were carried out with both media to quantify the drag forces. The correlation between the numerical and experimental drag forces highlights that the abrasive media with a pyramidal shape exhibits a higher shear resistance, and this is responsible for inducing higher mechanical loadings on the surfaces and, through this, for a faster decrease of the surface roughness
First-year university students entrepreneurial competence: Exploring the relationship between grit, creative self-efficacy and entrepreneurial self-efficacy
No full textGrit, creative self-efficacy and entrepreneurial self-efficacy have been
associated with the development of entrepreneurial behaviours that can
prepare students for a rapidly changing world of work. The main purpose of
this study is to analyse the relationship between the three variables amongst
first-year university students. A positive relationship, albeit modest, was
found between grit and the two measures of self-efficacy. Furthermore,
findings suggest that grit can be considered a predictor variable for student
self-efficacy beliefs in the context of entrepreneurship. However, this
relationship was found to be weak and not to offer significant opportunities
for the improvement of student creative and entrepreneurial self-perception,
beyond those already contemplated in social cognitive theory. Moreover,
results revealed a significant and robust positive relationship between
creative and entrepreneurial self-perceptions in university students. The
strong relationship found between creative and entrepreneurial self-efficacy
renders an opportunity to develop informed interventions directed towards
improving student entrepreneurial self-perceptions. In this regard, the results
suggest the importance of cultivating creativity in educational institutions
The Soret coefficients of the ternary system water/ethanol/triethylene glycol and its corresponding binary mixtures
Full text linkThermodiffusion in ternary mixtures is considered prototypic for the Soret effect of truly multicomponent systems. We discuss ground-based measurements of the Soret coefficient along the binary borders of the Gibbs triangle of the highly polar and hydrogen bonding ternary DCMIX3-system water/ethanol/triethylene glycol. All three Soret coefficients decay with increasing concentration, irrespective of the choice of the independent component, and show a characteristic sign change as a function of temperature and/or composition. With the exception of triethylene glycol/ethanol at high temperatures, the minority component always migrates toward the cold side. All three binaries exhibit temperature-independent fixed points of the Soret coefficient. The decay of the Soret coefficient with concentration can be related to negative excess volumes of mixing. The sign changes of the Soret coefficients of the binaries allow to draw far-reaching conclusions about the signs of the Soret coefficients of the corresponding ternary mixtures. In particular, we show that at least one ternary composition must exist, where all three Soret coefficients vanish simultaneously and no steady-state separation is observable
A Holistic and Interoperable Approach towards the Implementation of Services for the Digital Transformation of Smart Cities: The Case of Vitoria-Gasteiz
Full text linkCities in the 21st century play a major role in the sustainability and climate impact reduction challenges set by the European agenda. As the population of cities grows and their environmental impact becomes more evident, the European strategy aims to reduce greenhouse gas emissions—the main cause of climate change. Measures to reduce the impact of climate change include reducing energy consumption, improving mobility, harnessing resources and renewable energies, integrating nature-based solutions and efficiently managing infrastructure. The monitoring and control of all this activity is essential for its proper functioning. In this context, Information and Communication Technology (ICT) plays a key role in the digitisation, monitoring, and managing of these different verticals. Urban data platforms support cities on extracting Key Performance Indicators (KPI) in their efforts to make better decisions. Cities must be transformed by applying efficient urban planning measures and taking into account not only technological aspects, but also by applying a holistic vision in building solutions where citizens are at the centre. In addition, standardisation of platforms where applications are integrated as one is necessary. This requires interoperability between different verticals. This article presents the information platform developed for the city of Vitoria-Gasteiz in Spain. The platform is based on the UNE 178104 standard to provide a holistic architecture that integrates information from the different urban planning measures implemented in the city. The platform was constructed in the context of the SmartEnCity project following the urban transformation strategy established by the city. The article presents the value-added solutions implemented in the platform. These solutions have been developed by applying co-creation techniques in which stakeholders have been involved throughout the process. The platform proposes a step forward towards standardization, harmonises the integration of data from multiple vertical, provides interoperability between services, and simplifies scalability and replicability due to its microservice architecture
Hidrogeno tren baten diseinu eta operazioaren optimizazioa
Full text linkThis paper proposes an optimization methodology based on genetic algorithms for the design and operation of a hydrogen train. Indeed, the proposed approach optimizes the size of the hydrogen fuel cell, the size of the battery, and the energy management strategy. The aim of the optimization is to minimize the life cycle cost of the train. In order to validate the proposed methodology, a case study based on a real railway line is proposed. The results of the optimization are compared with a base case, what unveils that with the proposed methodology the total cost of the train can be reduced a 4.9%. The results validate the proposed methodology.Artikulu honek hidrogeno tren baten diseinu eta operazioa optimizatzeko algoritmo genetikoetan oinarritutako metodologia bat proposatzen du. Hain zuzen ere, metodologiaren bidez hidrogeno pilaren tamaina, bateriaren tamaina, eta kudeaketa energetikoko estrategia optimizatzen dira, helburua trenaren bizitza-ziklo osoko kostua minimizatzea izanik. Proposatutako metodologia balidatzeko benetako trenbide linea batean oinarritutako ikerketa kasu bat aurkezten da. Optimizazioak itzulitako emaitza oinarrizko kasu batekin alderatzen da, trenaren kostu totala % 4,9 murrizten dela frogatuz. Lortutako emaitzek metodologiaren eraginkortasuna egiaztatzen dute
DC-Link Neutral Point Control for 3L-NPC Converters Utilizing Selective Harmonic Elimination PWM
Full text linkSelective harmonic elimination–pulsewidth modulation (SHE–PWM) is a modulation technique widely used to improve the efficiency and harmonic content in medium-voltage high-power converters. Among these converters, the three-level neutral-point-clamped (3L-NPC) converter is one of the most utilized topologies. However, the 3L-NPC converter requires a proper balancing of dc-link capacitor voltages. This article presents a control technique, based on pulse shifting method, to regulate the neutral point voltage when SHE-PWM is utilized. The proposed technique performs well with any power factor and it can also be directly applied to T-type converters and easily extrapolated to other multilevel topologies. The proposed method is experimentally validated in a scaled-down power converter and a full-scale medium-voltage 3L-NPC converter