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Hardware-in-the-loop performance analysis of a railway traction system under sensor faults
Get PDFFault mode and effects analysis (FMEA) has been used during decades for analysing the effects of faults in different applications. Initially, FMEA based on risk priority numbers provided information about the effects in the system, but during the last years different approaches have been developed to obtain a more robust risk evaluation. The proposed enhanced FMEA can provide the quantitative effects of sensor faults in a railway traction drive, in variables such as torque, current and voltages. In addition to the previous work, quantitative effects on overall performance indicators, such as energy efficiency and comfort, are obtained too. Hardware-in-the-loop (HIL)-based fault injection approach has been used to generate fault scenarios. The test platform is composed of a real-time simulator and a commercial traction control unit for a railway application
On the Role of a ZDDP in the Tribological Performance of Femtosecond Laser-Induced Periodic Surface Structures on Titanium Alloy against Different Counterbody Materials
Get PDFLaser-induced periodic surface structures (LIPSS, ripples) with ~500–700 nm period were produced on titanium alloy (Ti6Al4V) surfaces upon scan processing in air by a Ti:sapphire
femtosecond laser. The tribological performance of the surfaces were qualified in linear reciprocating sliding tribological tests against balls made of di erent materials using di erent oil-based lubricants. The corresponding wear tracks were characterized by optical and scanning electron microscopy and confocal profilometry. Extending our previous work, we studied the admixture of the additive 2-ethylhexyl-zinc-dithiophosphate to a base oil containing only anti-oxidants and temperature stabilizers. The presence of this additive along with the variation of the chemical composition of the counterbodies allows us to explore the synergy of the additive with the laser-oxidized nanostructures
Design of a Solid-State Circuit Breaker for a DC Grid-Based Vessel Power System
Get PDFElectric propulsion and integrated hybrid power systems can improve the energy efficiency
and fuel consumption of different kinds of vessels. If the vessel power system is based on DC grid
distribution, some benefits such as higher generator e ciency and lower volume and cost can be
achieved. However, some challenges remain in terms of protection devices for this kind of DC
grid-based power system. The absence of natural zero crossing in the DC current together with the
fast and programmable breaking times required make it challenging. There are several papers related
to DC breaker topologies and their role in DC grids; however, it is not easy to find comprehensive
information about the design process of the DC breaker itself. In this paper, the basis for the design of
a DC solid-state circuit breaker (SSCB) for low voltage vessel DC grids is presented. The proposed
SSCB full-scale prototype detects and opens the fault in less than 3 us. This paper includes theoretical
analyses, design guidelines, modeling and simulation, and experimental results
Neural Network Direct Control with Online Learning for Shape Memory Alloy Manipulators
Get PDFNew actuators and materials are constantly incorporated into industrial processes, and additional challenges are posed by their complex behavior. Nonlinear hysteresis is commonly found in shape memory alloys, and the inclusion of a suitable hysteresis model in the control system allows the controller to achieve a better performance, although a major drawback is that each system responds in a unique way. In this work, a neural network direct control, with online learning, is developed for position control of shape memory alloy manipulators. Neural network weight coefficients are updated online by using the actuator position data while the controller is applied to the system, without previous training of the neural network weights, nor the inclusion of a hysteresis model. A real-time, low computational cost control system was implemented; experimental evaluation was performed on a 1-DOF manipulator system actuated by a shape memory alloy wire. Test results verified the effectiveness of the proposed control scheme to control the system angular position, compensating for the hysteretic behavior of the shape memory alloy actuator. Using a learning algorithm with a sine wave as reference signal, a maximum static error of 0.83º was achieved when validated against several set-points within the possible range
Self-efficacy in first-year university students: a descriptive study
Get PDFThe study and analysis of the self-efficacy beliefs of students has become an
important line of educational research. The purpose of this study, conducted
at Mondragon University (Spain), is to explore the different perceptions
concerning the creative and entrepreneurial self-efficacy of students on their
entrance to university. Results revealed clear patterns with regards to
discipline and gender. Students commencing their degrees in social sciences
show lower creative and entrepreneurial self-efficacy perceptions than their
peers in other disciplines. Women show lower scores than men across
different disciplines with the exception of women commencing engineering
studies.
Self-efficacy has been related to student motivation and learning and has
been found influential in the choice of the professional career. The high
significance of this construct in education makes the results of this study have
clear implications for the development of learning environments that address
the differences found between gender and disciplines. Directions for future
research are also indicated
Hibridazio metodologiaren esperimentazioa euskarazko komunikabide batean
Get PDFHibridazioa da ekonomia arloan gero eta gehiago erabiltzen ari diren berrikuntzarako
metodologia bat. Elkarrekin inolako zerikusirik ez daukaten bi edo hiru enpresa edo sektore
elkartzen dira, produktu berritzaile bat asmatzeko, bi edo hiru aldeen probetxurako. Metodologia
hori esperimentatu nahi izan da euskarazko komunikabideetan. Berria egunkaria aukeratu
da esperimentazioa egiteko. Berria-k sare sozialetan duen jarduna eta gazteek Berria-rekin
duten harremana aztertu ondoren, hibridaziorako proposamen batzuk egin zaizkio euskarazko
egunkariari, kontuan hartuta gazteek batez ere sakelako aplikazioak erabiltzen dituztela. Hainbat
bilera eta elkarrizketen ondotik, erabaki da hibridazioa egitea Tabakalerarekin. Ez da lortu ezer
sortzea ahalegin horretatik, baina etorkizunerako pista batzuk eman ditu, metodologia hori
lantzeari begira.La hibridación es una metodología innovadora cada vez más usada en el campo de la
economía. Consiste en que dos o tres empresas o sectores, sin relación alguna entre ellos, se
unen para crear un producto innovador que beneficia a todas las partes. Se ha experimentado
esa metodología en los medios de comunicación euskaldunes. En concreto, se ha seleccionado
el diario Berria. Después de analizar la actividad de Berria en las redes sociales y las relaciones
de los jóvenes con Berria, se le han hecho unas propuestas de hibridación, teniendo en cuenta
que los jóvenes tienden a usar aplicaciones móviles. Tras varias reuniones y entrevistas, se ha
optado por efectuar una hibridación con Tabakalera. Ese esfuerzo no ha dado frutos, pero ha
proporcionado unas pistas para trabajar dicha metodología de cara al futuro
Testing successful Business Model using System Dynamics
Get PDFIn our increasingly globalised economy, managing continuous change whilst remaining competitive and dynamic has become a central issue for firms in the industrial sector. One of the elements for obtaining this competitiveness is the value creation model of the firm. The most important challenges in firms are characterised by dynamic complexity which makes it difficult to understand factors in their context. Consequently management and decision making is hindered (Antunes et al., 2011). Business models are characterised by complexity and dynamism. Performance of the firm is a complex topic determined by the large amount of variables that can be involved in the system, and the different effects that influence the system in the short and long term. Due to this complexity a systemic view is required, that is, an holistic view of the whole system. Such a systemic view enables managers to make decisions based on evidence rather than intuition and personal experiences, as they understand how the whole system works. Thus, the main aim of this research is to use an empirical tool such as System Dynamics (SD), to support and sustain firms in the identification of new constructs related to their Business Model (BM)
Industrial Cyber-Physical System Evolution Detection and Alert Generation
Get PDFIndustrial Cyber-Physical System (ICPS) monitoring is increasingly being used to make decisions that impact the operation of the industry. Industrial manufacturing environments such as production lines are dynamic and evolve over time due to new requirements (new customer needs, conformance to standards, maintenance, etc.) or due to the anomalies detected. When an evolution happens (e.g., new devices are introduced), monitoring systems must be aware of it in order to inform the user and to provide updated and reliable information. In this article, CALENDAR is presented, a software module for a monitoring system that addresses ICPS evolutions. The solution is based on a data metamodel that captures the structure of an ICPS in different timestamps. By comparing the data model in two subsequent timestamps, CALENDAR is able to detect and effectively classify the evolution of ICPSs at runtime to finally generate alerts about the detected evolution. In order to evaluate CALENDAR with different ICPS topologies (e.g., different ICPS sizes), a scalability test was performed considering the information captured from the production lines domain
A mechanistic model to predict cutting force on orthogonal machining of Aluminum 7475-T7351 considering the edge radius
Get PDFThe ploughing force related with action of edge radius is an important factor which influences flow stress, chip formation or surface integrity. Some fraction of the cutting forces are called parasitic (additional) forces and they do not contribute on chip formation process. These forces are usually assumed to be the cutting force (constant value) for zero feed. However, this effect is related with the edge radius. To improve force modelling prediction, a new mechanistic model to predict cutting force considering edge radius is presented. The model was developed for two cutting speeds and in a wide range of feeds for three edge radii. The model was validated with additional experimental tests, achieving relative errors lower than 3%
A New Method to Evaluate Good Design for Brand Recognition in the Digital World
Get PDFVisual aesthetics has become a crucial element in strengthening brand experience. In the digital era, however, designers need to approach aesthetics from a holistic standpoint where both traditional and more modern factors are taken into consideration. In this paper we present digital BrandUX, a new method to improve brand consistency through the evaluation of aesthetic features. It builds on the Design Format Analysis (DFA) of Warell(2001) with the addition of a structured step-by-step approach.To test the method we analysed twoweb sites using both DFA and digital BrandUX. The results showed that digital BrandUX is a promising advance in aesthetic evaluation, assisting designers in identifying a greater number of visual aesthetic features. Moreover, the method ensured that the designers exploredand identified all types of factors,with the exception of language. Future lines include the development of a handbook to improve ease of use of the method