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Fractional viscoelastic models for the estimation of the frequency response of rubber bushings based on relaxation tests
Get PDFEstimation of the viscoelastic properties of rubber bushings at very high frequencies (up to 2 kHz) is a challenge
for many damping component manufacturers in the design stage of a quality monitoring procedure. This
investigation is focused on the capability of lower strain rate testing procedures, such as relaxation tests, to
estimate and extrapolate the dynamic behavior of rubber bushings from low to moderate frequencies. Fractional
Zener models are employed to approach bushing behavior in experimental relaxation tests, thus leading to
a linear viscoelastic model which is employed to estimate the dynamic behavior of rubber bushing under
harmonics loads up to 150 Hz. The validation of this extrapolation procedure is performed by comparing these
analytical results with experimental dynamic harmonic tests applied to the same rubber bushings. The deviation
between both curves demonstrates that it is difficult to compare the behavior from very small deformation rates
(relaxation tests) to higher deformation rates (harmonic dynamic tests) due to the nonlinear behavior of the
rubber and its amplitude dependence. However, this investigation demonstrates that the relaxation tests contain
enough data to define the frequency behavior of linear viscoelastic materials up to moderate frequencie
Towards learner performance evaluation in iVR learning environments using eye-tracking and machine-learning
No full textActualmente, el uso de los datos del seguimiento de la mirada en entornos de aprendizaje de Realidad Virtual inmersiva (iVR) está destinado a ser una herramienta fundamental para maximizar los resultados de aprendizaje, dada la naturaleza poco intrusiva del eye-tracking y su integración en las gafas comerciales de Realidad Virtual. Pero, antes de que se pueda generalizar el uso del eye-tracking en entornos de aprendizaje, se deben identificar las tecnologías más adecuadas para el procesamiento de datos. Esta investigación propone el uso de técnicas de aprendizaje automático para este fin, evaluando sus capacidades para clasificar la calidad del entorno de aprendizaje y predecir el rendimiento de aprendizaje del usuario. Para ello, se ha desarrollado una experiencia docente en iVR para aprender el manejo de un puente-grúa. Con esta experiencia se ha evaluado el rendimiento de 63 estudiantes, tanto en condiciones óptimas de aprendizaje como en condiciones con factores estresores. El conjunto de datos final incluye 25 características, siendo la mayoría series temporales con un tamaño de conjunto de datos superior a 50 millones de puntos. Los resultados muestran que la aplicación de diferentes clasificadores como KNN, SVM o Random Forest tienen una alta precisión a la hora de predecir alteraciones en el aprendizaje, mientras que la predicción del rendimiento del aprendizaje del usuario aún está lejos de ser óptima, lo que abre una nueva línea de investigación futura. Este estudio tiene como objetivo servir como línea de base para futuras mejoras en la precisión de los modelos mediante el uso de técnicas de aprendizaje automático más complejas.At present, the use of eye-tracking data in immersive Virtual Reality (iVR) learning environments is set to become a
powerful tool for maximizing learning outcomes, due to the low-intrusiveness of eye-tracking technology and its integration
in commercial iVR Head Mounted Displays. However, the most suitable technologies for data processing should first
be identified before their use in learning environments can be generalized. In this research, the use of machine-learning
techniques is proposed for that purpose, evaluating their capabilities to classify the quality of the learning environment and
to predict user learning performance. To do so, an iVR learning experience simulating the operation of a bridge crane
was developed. Through this experience, the performance of 63 students was evaluated, both under optimum learning
conditions and under stressful conditions. The final dataset included 25 features, mostly temporal series, with a dataset size
of up to 50M data points. The results showed that different classifiers (KNN, SVM and Random Forest) provided the
highest accuracy when predicting learning performance variations, while the accuracy of user learning performance was
still far from optimized, opening a new line of future research. This study has the objective of serving as a baseline for future
improvements to model accuracy using complex machine-learning techniques.Esta investigación ha sido financiada por el Proyecto ACIS (INVESTUN/21/BU/0002) de la Consejería de Empleo e Industria de la Junta de Castilla y León (España), el Proyecto Erasmus+ RISKREAL (2020-1-ES01-KA204-081847) de la Comisión Europea, el Proyecto HumanAid (TED2021-129485B-C43) del Ministerio Español de Ciencia e Innovación y el Programa Margarita Salas del Ministerio Español de Universidades financiado por NextGenerationEU
Sociodemographic Variables and Body Mass Index Associated with the Risk of Eating Disorders in Spanish University Students
No full textThe passage through university is a complex experience that can heighten
personal susceptibility to eating disorders. The objective of this research is to determine how gender,
age, course, educational faculty, and body mass index (BMI) can influence the risk of eating disorders
among university students
A multistart tabu search-based method for feature selection in medical applications
No full textIn the design of classification models, irrelevant or noisy features are often generated. In some cases, there may even be negative interactions among features. These weaknesses can degrade the performance of the models. Feature selection is a task that searches for a small subset of relevant features from the original set that generate the most efficient models possible. In addition to improving the efficiency of the models, feature selection confers other advantages, such as greater ease in the generation of the necessary data as well as clearer and more interpretable models. In the case of medical applications, feature selection may help to distinguish which characteristics, habits, and factors have the greatest impact on the onset of diseases. However, feature selection is a complex task due to the large number of possible solutions. In the last few years, methods based on different metaheuristic strategies, mainly evolutionary algorithms, have been proposed. The motivation of this work is to develop a method that outperforms previous methods, with the benefits that this implies especially in the medical field. More precisely, the present study proposes a simple method based on tabu search and multistart techniques. The proposed method was analyzed and compared to other methods by testing their performance on several medical databases. Specifically, eight databases belong to the well-known repository of the University of California in Irvine and one of our own design were used. In these computational tests, the proposed method outperformed other recent methods as gauged by various metrics and classifiers. The analyses were accompanied by statistical tests, the results of which showed that the superiority of our method is significant and therefore strengthened these conclusions. In short, the contribution of this work is the development of a method that, on the one hand, is based on different strategies than those used in recent methods, and on the other hand, improves the performance of these methods.The authors are grateful to the following entities and projects: The Spanish Research Agency (Projects PID2019-104263RB-C44 and PDC2021-121021-C22 and PID2022-139543OB-C44). The Regional Government of “Castilla y León” and FEDER funds (Project BU056P20)
“The connections between the enemy at home and the enemy in Spain”: Langston Hughes’ black internationalism in the Spanish Civil War
No full textFrom July to December 1937, Langston Hughes travelled to Spain to cover the Civil War as a correspondent. The five months he spent travelling throughout Spain gave rise to a prolific repertoire on which the author left a manifest ideological imprint. His observations from within and the ideological perspectives revealed the potential of travel writing as a tool to re-examine the local and international boundaries critically. This paper navigates Hughes’ dispatches in wartime Spain, which distanced him from traditional journalistic practices by demonstrating a clear preference for the ordinary, and a subjective interpretation of the events driven by an unambiguous ideological affiliation to the Loyalist faction. The analysis of the texts sheds light on how international travel facilitated Black connections and on the importance of travel to the politics of Black internationalism
Un enfoque sociológico-antropológico a la(s)identidad(es) islámica(s)
No full textEl objetivo de este capítulo es proporcionar algunas claves sociológicas y antropológicas que permitan comprender la complejidad y heterogeneidad de las identidades islámicas cuestionando la existencia de un única, homogénea y a-histórica "identidad islámica". Para ello abordaré, en primer lugar, las dificultades intrínsecas que se manifiestan en el análisis sociológico y antropológico de la identidad, debido a su carácter difuso y evasivo. Y, en segundo, lugar, analizaré la complejidad de las identidades islámicas desde diferentes perspectivas y/o dimensiones (la perspectiva individual, la sociocultural, la histórica y la geopolítica), examinando la relevancia del contexto jurídico-político y del contexto socio-cultural en la forma en cómo se construyen y cómo se experimentan las identidades islámicas
Formulation and evaluation of anion transporters in nanostructured lipid carriers
No full textSix novel click-tambjamines (1–6) bearing an alkyl chain of varying length linked to the imine moiety have been formulated in nanostructured lipid carriers (NLCs) to evaluate their transmembrane anion transport activity both when free (i.e., not encapsulated) and nanoformulated. Nanostructured lipid carriers (NLCs) are an example of drug delivery systems (DDSs) that stand out because of their versatility. In this work we show that NLCs can be used to efficiently formulate highly lipophilic anionophores and experiments conducted in model liposomes reveal that these formulations are adequate to deliver anionophores without compromising their transport activity. This result paves the way to facilitate the study of highly lipophilic anionophores and their potential use as future drugs.This research has been financially supported by Consejería de Educación de la Junta de Castilla y León and European Regional Development Fund (ERDF) (project BU067P20), Ministerio de Ciencia e Innovación (project PID2020-117610RB-I00), Gobierno Vasco (Elkartek program 2021 KK-2021/00052), and Alava Innova program 2021 (INNOAS-2021/00003) of the Provincial Council of Alava. D. A.-C. and I. C.-B. thank Consejería de Educación de la Junta de Castilla y León, ERDF and European Social Fund (ESF) for their pre-doctoral and post-doctoral contracts, respectively
Manual de Neurología para Terapia Ocupacional
No full textEl objetivo del presente manual es presentar los conceptos básicos de la Neurología necesarios para un estudiante y un profesional de Terapia Ocupacional y de otras disciplinas afines como la Fisioterapia, sin necesidad de profundizar en exceso en otros aspectos que habitualmente se presentan en obras clásicas dirigidas a profesionales con formación médica, como es el tratamiento farmacológico
Recent Transformations in the Morphology of Spanish Medium-Sized Cities: From the Compact City to the Urban Area
No full textOver the last few decades, within the framework of remarkable urban expansion accompanying a real-estate boom in Spain, it has been medium-sized cities that have registered the most drastic changes in morphology. Currently, about 50% of urbanised land was developed after 1980. Historically compact and dense urban structures have been transformed, with new urbanised spaces expanding into the outskirts. High land consumption has created sprawling, fragmented and scattered urban areas. These are new, more complex and multifunctional urban structures, and there has been a change in the scale of urbanisation, in the forms and in the resulting urban landscape. However, the growth model which has caused these transformations is defined by hardly sustainable land-use patterns. The number of medium-sized cities has increased by around 50%, while the number of houses built has grown by 109% and developed land by 87% between 1981 and 2021. This paper analyses these recent dynamics through the statistical treatment of growth patterns and their cartographic analysis using GIS technology. The significant modification of urban forms at this scale in the Spanish urban system is confirmed. The paper also reflects on the lack of sustainability in the prevailing model with respect to the 2030 city strategy.This research was carried out thanks to funding received through the public call for R+D+i projects granted by the Spanish Ministry of Science and Innovation (MCIN): “Spanish medium-sized cities: urbanisation and urban policies. 40 years of democratic city councils:1979–2019” (RTI2018-096435-B-C21+C22) and “Fragmentation and socio-spatial segregation in Spanish medium-sized cities and their urban areas (2001–2021)” (PID2021-124511NB-C21+C22)
Functionality and Quality of Life with Parkinson’s Disease after Use of a Dynamic Upper Limb Orthosis: A Pilot Study
No full textParkinson’s disease (PD) is a chronic, neurodegenerative movement disorder, whose symptoms have a negative impact on quality of life and functionality. Although its main treatment is pharmacological, non-pharmacological aids such as the dynamic elastomeric fabric orthosis (DEFO) merit an evaluation. Our objective is to assess the DEFO in upper limb (UL) functional mobility and in the quality of life of PD patients. A total of 40 patients with PD participated in a randomized controlled crossover study, and were assigned to a control group (CG) and to an experimental group (EG). Both groups used the DEFO for two months, the experimental group the first two months of the study and the control group the last two. Motor variables were measured in the ON and OFF states at the baseline assessment and at two months. Differences from the baseline assessment were observed in some motor items of the Kinesia assessment, such as rest tremor, amplitude, rhythm or alternating movements in the ON and OFF states with and without orthosis. No differences were found in the unified Parkinson’s disease rating scale (UPDRS) or the PD quality-of-life questionnaire. The DEFO improves some motor aspects of the UL in PD patients but this does not translate to the amelioration of the standard of functional and quality-of-life scales.This study was supported by grants for the financing of research projects in biomedicine, health management and social health care approved by the Regional Health Management of the Junta de Castilla y León (No. EXP. GRS2020/A/19). Regional Health Management of Castilla y León–Sacyl GRS/2010/A/19