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A Controlled Thermoalgesic Stimulation Device for Exploring Novel Pain Perception Biomarkers
Full text linkObjective: To develop a new device for identifying physiological markers of pain perception by reading the brain's electrical activity and hemodynamic interactions while applying thermoalgesic stimulation. Methods: We designed a compact prototype that generates well-controlled thermal stimuli using a computer-driven Peltier cell while simultaneously capturing electroencephalography (EEG) and photoplethysmography (PPG) signals. The study was performed on 35 healthy subjects (mean age 30.46 years, SD 4.93 years; 20 males, 15 females). We first determined the heat pain threshold (HPT) for each subject, defined as the maximum temperature that the subject can withstand when the Peltier cell gradually increased the temperature. Next, we defined the painful condition as the one occurring at temperature equal to 90% of the HPT, comparing this to the no-pain state (control) in the absence of thermoalgesic stimulation. Results: Both the one-dimensional and the two-dimensional spectral entropy (SE) obtained from both the EEG and PPG signals differentiated the condition of pain. In particular, the SE for PPG was significantly reduced in association with pain, while the SE for EEG increased slightly. Moreover, significant discrimination occurred within a specific range of frequencies, 26-30 Hz for EEG and about 5-10 Hz for PPG. Conclusion: Hemodynamics, brain dynamics and their interactions can discriminate thermal pain perception. Significance: The possibility of monitoring on-line variations in thermal pain perception using a similar device and algorithms may be of interest to study different pathologies that affect the peripheral nervous system, such as small fiber neuropathies, fibromyalgia or painful diabetic neuropathy
The link between HIWPs and well-being at work: the mediating role of trust
Full text linkPurpose – This paper examines the extent to which investment in human capital (HC) influences employee well-being, focusing on companies in the Basque Country in Northern Spain. Specifically, it analyzes the effects of worker perceptions of high-involvement work system (HIWS) on job satisfaction (JS) and affective commitment (AC), directly and through the mediating role of trust in management. This trust mediating role was also explored by analyzing the isolated effects of high-involvement work processes (power, information, reward and knowledge [PIRK] enhancing practices) on JS and AC.
Design/methodology/approach – The structural equation modeling (SEM) approach was used on a sample of 2,199 employees from 425 organizations working in different industries. As the study was performed at the organizational level, aggregation was conducted first.
Findings – The findings revealed that trust partially mediated the relationship between HIWS and JS, although AC was directly predicted by the system. In contrast, a trust mediating role was confirmed in the relationship between all PIRK processes, JS and AC.
Originality/value –This study highlights the “hinge”role of trust in linking high-involvement work practices (HIWPs) as an approach to assess HC in organizations and well-being at work. It further conceptualizes HIWS via a PIRK model and operationalizes it through systemic and dimensional approach
A digital twin framework for the simulation and optimization of production systems
Full text linkIndustry 4.0 has raised the expectations on productivity, automation, and resource efficiency of manufacturing systems. This paper proposes a digital twin framework for the simulation and optimization of production lines and cells that can be used in the design and operation stages. The framework is supported by an architecture that connects manufacturing and machine tool data (digital shadow), the discrete event simulation model and the optimization engine, allowing for a variety of functionalities to plan and manage the production system. A use case is provided to demonstrate this framework, implemented in an automated line for the manufacturing of railway axles
Giza eta gizarte-zientziak eta irakasleen Prestakuntzarako unibertsitate-masterra: paradigma epistemologikoa
Full text linkHumanitate eta Gizarte Zientzien arloko Irakasleak Prestatzeko Masterra egiten ari di-ren ikasleek gizarteaz eta gizarteak irakaskuntzari buruz duen ikuspegiaz gogoeta egin behar luketela iri-tzita, eta, horrenbestez, eta, halaber irakaskuntzaren gizarte-testuingurua zein den kontuan hartu behar luketela kontuan hartuta, hiru galderari erantzuten saiatu behar genuke: 1) Zein da gizarte-ezagutzaren funtzioa gaur egun? 2) Zergatik eta zertarako irakasten ditugu gizarte-zientziak? eta 3) Zer eduki trans-mititu nahi ditugu? Lehenbiziko bi galderei erantzunez, gizarte-zientzien zer paradigma mota sustatu nahi dugun pentsatu eta hausnartuko dugu, eta horrek eramango gaitu hirugarren galderari erantzuteko propo-samenak egitera. Nolanahi ere, azken galdera horri erantzun aurretik, gogoeta egin beharra dago ezagutza-arloko irakasle izateko asmoa duten pertsonekin, gai izan daitezen kontzienteki erantzuteko zergatik eta zertarako erabaki duten gizarte-zientzien eredu jakin bat sustatzea.In the belief that students pursuing a Master’s degree in Teacher Training in the Hu-manities and Social Sciences should reflect on society and society’s view of teaching, and therefore also keeping in mind that they should consider what the social context of teaching should be, we will try to answer the following three questions: 1) What is the function of social knowledge today? 2) Why and for what purpose do we teach the social sciences? and 3) What content do we wish to transmit? In answering the first two questions, we will think about and reflect on what kind of paradigm we wish to promote in the social sciences, and that will lead us to propose answers to the third question. In any case, before we answer the final question, reflection is needed with those who intend to become teach-ers of knowledge, so that they will be able to consciously explain why and for what purpose they de-cided to promote a given model of the social sciences
New design for assembly (DfA) methodology for large and heavy parts assembled on site
Full text linkA 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
Generating metamorphic relations for cyber-physical systems with genetic programming: an industrial case study
Full text linkOne of the major challenges in the verification of complex industrial Cyber-Physical Systems is the difficulty of determining whether a particular system output or behaviour is correct or not, the socalled test oracle problem. Metamorphic testing alleviates the oracle problem by reasoning on the relations that are expected to hold among multiple executions of the system under test, which are
known as Metamorphic Relations (MRs). However, the development of effective MRs is often challenging and requires the involvement of domain experts. In this paper, we present a case study aiming at automating this process. To this end,we implemented GAssertMRs, a tool to automatically generate MRs with genetic programming. We assess the cost-effectiveness of this tool in the context of an industrial case study from the elevation domain. Our experimental results show that in most cases GAssertMRs outperforms the other baselines, including manually generated MRs developed with the help of domain experts. We then describe the lessons learned from our experiments and we outline the future work for the adoption of this technique by industrial practitioners
The effect of cross-section geometry on crushing behaviour of 3D printed continuous carbon fibre reinforced polyamide profiles
Full text linkThe present study has analysed the effect of cross-section geometry and the printing pattern of continuous carbon reinforced polyamide on the axial and radial crushing behaviour. Each geometry and printing pattern generated singular defects, but the most relevant microstructural aspect resulted the fibre orientation. The geometry with the re-entrant shape and Concentrical printing pattern was identified as the best profile for axial and radial crushing loadings, with a SEA of 23.9 and 5.9 kJ/kg. In spite of axial SEA values are far from those values obtained for composite profile manufactured by conventional process, radial SEA value obtained with steered fibres was at least 2–3 times higher than the best value found in the literature. Thus, concentrically 3D printed with steered fibres layers, could be exploited for radially loaded hollow profiles applications. Despite studied cross-section are not good enough under axial loads, 3D printing allows complex geometries and exploring more sophisticated cross-sections could lead to higher axial SEA values
Analysis of the Tool Stick-Out Influence on Machining Chatter
Full text linkIncreased stability in machining processes is highly desired by all machining industries when vibrations and specially chatter occur. This phenomenon is defined as a self-excited vibration that occurs due to the regeneration of waviness of the workpiece surface. In machining industry, the trend is to rely on the trial and error method or mere experience when deciding the machining spindle speeds, depths of cut and tool stick-outs, all of which are parameters directly related to chatter occurrence. Currently, the shortest possible tool stick-out is chosen by default, but literature has proven that longer stick-outs may bring some advantages when it comes to material removal rates. Aiming to prove this theory, this paper will discuss the influence of the tool stick-out on machining chatter occurrence. To that end, the effect of the tool stick-out on the modal parameters of the system, on the Stability Lobe Diagram (SLD) and on productivity will be analysed. Therefore, a number of Tap-Tests to different tool/tool-holder/stick-out combinations have been performed, in order to gather the data (FRFs and SLDs) where the analysis is based on. Last but not least, some machining tests have been conducted aiming to compare the theoretical chatter occurrence conditions, provided by the SLD, with the experimental ones. For that, two Al5083 workpieces have been slot milled under different cutting conditions, facilitating the unexpected results wherein the conclusions have been based upon
Interferentzia elektromagnetikoaren azterketa potentzia-elektronikako sistemetan Si-WBG trantsizio teknologikoaren testuinguruan
Full text linkThis research project has analysed the effect of electromagnetic interference (EMI) on power electronics systems, as well as the effect of the transition from silicon-based devices to WBG-based devices. The main goal has been to identify the parameters that have an impact on EMI generation and propagation. A test bench has been designed to analyse the effect of varying these parameters on the main signals (currents and voltages) in the time and frequency domain. The results obtained are intended to provide the electronic designers with a tool to ensure that their designs comply with EMC regulations, as well as maximising energy efficiency.Ikerketa honek potentzia-elektronikako sistemetan sortzen den interferentzia elektromagnetikoa (EMI, Electromagnetic Interference) aztertu du, baita silizioan oinarritutako gailuetatik banda zabaleko erdieroaleetan (WBG, Wide Band Gap) oinarritutako gailuetara igarotzeak duen eragina ere. Helburua EMIaren sorkuntzan eta hedapenean eragiten duten parametroak identifikatzea izan da. Saiakuntza banku bat diseinatu da parametro hauen aldakortasunak denbora- zein maiztasun-eremuko seinaleetan duen efektua aztertu ahal izateko. Lortutako emaitzekin elektronika-diseinatzaileei potentziabihurgailuen diseinurako tresna bat eman nahi zaie; horren bitartez, energia-efizientzia maximoa lortzen saiatzeaz gain, EMI-sorkuntzaren eta bateragarritasun elektromagnetikoko (EMC, Electromagnetic Compatibility) araudiaren betekizunei erreparatu ahal izango diete
Building an Air Turbine Conditional Anomaly Detection Approach for Wave Power Plants
Full text linkThe Mutriku Wave Power Plant (WPP) is a wave energy conversion plant based on the oscillating water column technology (OWC). The energy production and the health state of the plant are directly dependent on the sea-state conditions along with component-specific operation efficiency and failure modes. In this context, this paper presents a preliminary air turbine conditional anomaly detection (CAD) approach for condition monitoring of the Mutriku WPP. The proposed approach is developed based on an ensemble of Gaussian Mixture models, where each anomaly detection model learns the expected air turbine operation conditioned on specific seastates information. Early results show that the integration of sea-states in the anomaly detection learning process improves the discrimination capability of the anomaly detection model