Procedimiento para la homologación de sistemas de protección de peatones mediante la realización de ensayos virtuales

La mitad de las muertes producidas a nivel mundial como consecuencia de los accidentes de tráfico corresponden a los llamados usuarios vulnerables de la vía pública. Los peatones son la figura más débil, de forma que centrar la atención de la seguridad vial en ellos podría conllevar significantes descensos en el número de fallecidos y heridos graves. Para poder determinar las medidas a adoptar, resulta imprescindible conocer en detalle las causas que desencadenan el atropello, los eventos que se producen durante el transcurso del siniestro y las consecuencias lesivas que implica. Por ello, esta tesis doctoral comienza con una revisión de estudios disponibles en la literatura, con el fin de conocer en detalle el fenómeno biomecánico del atropello. Por otro lado, el papel que juegan los fabricantes de automóviles en la protección al peatón es fundamental. Éstos deben someter sus nuevos modelos de vehículos a ensayos de homologación para asegurar que cumplen con los requisitos mínimos de seguridad exigidos en materia de protección al peatón. Sin embargo, estos ensayos suelen ser destructivos y enormemente costosos, tanto en tiempo como en coste económico. Surge entonces el planteamiento de utilizar ensayos virtuales como alternativa a los ensayos experimentales de homologación. Las simulaciones han demostrado ser especialmente útiles en pruebas de tipo repetitivo, como es el caso de los ensayos de homologación de protección al peatón. Debido a esto, esta tesis doctoral se centra en evaluar si los actuales ensayos de homologación reflejan la realidad del atropello o si, por el contrario, deben ser mejorados. Todo ello se plantea desde las simulaciones hechas por ordenador y, por tanto, desde el punto de vista que implica utilizar ensayos virtuales de homologación.Half of global road deaths correspond to the so-called vulnerable road users. Among them pedestrians are the weakest element, so that focusing attention on road safety on them could lead to significant declines in the number of deaths and serious injuries. In order to determine the safety measures to adopt, it is essential to know the causes that trigger the pedestrian-vehicle collision, the events that occur during the course of the crash and the harmful consequences involved. Therefore, this doctoral thesis begins with a review of studies available in the literature, in order to know in detail the biomechanical phenomenon of a pedestrian crash. On the other hand, the role played by vehicle manufacturers in pedestrian protection is fundamental, since the vehicle design can significantly influence the severity of the crash. They must submit their new vehicle models to approval tests in order to ensure that they meet the minimum safety requirements for pedestrian protection. However, these tests are often destructive and enormously costly, both in time and in economic cost. Then arises the approach of using virtual trials as an alternative to experimental approval tests. The virtual testing has proved to be especially useful in tests of repetitive type, as it is the case of the homologation tests of pedestrian protection. Due to this, this doctoral thesis focuses on evaluating if the current approval tests reflect the reality of the pedestrian-vehicle collision or if, on the contrary, they should be improved. This research is raised from the simulations’ point of view, assuming virtual testing as viable and reliable alternative to the traditional physical approval tests.Programa Oficial de Doctorado en Ingeniería Mecánica y de Organización IndustrialPresidente: Vicente Díaz López.- Secretario: Emilio Velasco Sánchez.- Vocal: José Andrés Campón Domíngue

Is the virtual homologation for pedestrian protection viable?

One out of five deceased in traffic accidents is a pedestrian. In addition, pedestrians represent the 20 % of the hospitalized injured people. The deadliness rate of a pedestrian crash is significantly greater than for the rest of accidents. Thus, pedestrian crash is one of the more lethal traffic accidents and, consequently, pedestrians are the most vulnerable road users. Vehicle's design can influence immensely in the risk of seriousness of the accident. Regulations are the legal instruments in order to establish if a vehicle achieves the minimum safety requirements. Nevertheless, homologation implies costly and destructive tests. This problem could be solved by simulation techniques. Analyzing the viability of a virtual homologation is the main goal of this article. After studying pedestrian crash biomechanics, virtual tests will be performed using Finite Element software (Ls-Dyna) to assess the influence of the design of vehicle and the effect of a safety system (active bonnet). Comparison between virtual tests results and real tests allows deducing if the virtual homologation for pedestrian protection is viable

Experimental verification of the boundary conditions in the success of the Brazilian test with loading arcs. An uncertainty approach using concrete disks

The present work analyses the reliability of the Brazilian test with loading arcs. A new testing set up has allowed to determine in an effective way the real load of the failure initiation as this moment was not always or correctly detected by the universal testing machine. The instrumentation used is a simple and low-cost method that allows to know the possible pressure distribution in the contact zone as well as the final contact angle. It has been observed that the success of the test depends mainly on the surface finish of the parts involved, their geometric tolerances and the symmetry of the applied load. These boundary conditions have a direct effect in the contact pressure distribution. The possible failure modes observed experimentally have been simulated with the finite element methods. For this, the contact boundary condition has been changed and the possible stress distribution in term of Griffith equivalent stress has been obtained. The numerical analysis allows to study the influence of the initial contact condition on the success of the test and agrees with the experimental results. Furthermore, an uncertainty analysis in the expression of the tensile strength confirms that, when the test is valid, a crack appears suddenly in the central area of the disk, as observed experimentally, so there is no need to determine if the starting point is in the centre. Additionally, it has been observed that the initial crack length depends on the type of pressure distribution in the contact zone. Finally, a series of recommendations are given in order to minimize both the variability of the final contact angle and the risk of premature failure of the Brazilian disk

Surface Electromyography Study Using a Low-Cost System: Are There Neck Muscles Differences When the Passenger Is Warned during an Emergency Braking Inside an Autonomous Vehicle?

Deaths and serious injuries caused by traffic accidents is a concerning public health problem. However, the problem can be mitigated by the Autonomous Emergency Braking (AEB) system, which can avoid the impact. The market penetration of AEB is exponentially growing, and non-impact situations are expected to become more frequent. Thus, new injury patterns must be analysed, and the neck is particularly sensitive to sudden acceleration changes. Abrupt braking would be enough to be a potential risk for cervical spine injury. There is controversy about whether or not there are differences in cervical behaviour depending on whether passengers are relaxed or contract their muscles before the imminent accident. In the present manuscript, 18 volunteers were subjected to two different levels of awareness during an emergency braking test. Cervical muscles (sternocleidomastoid and trapezius) were analysed by the sEMG signal captured by means of a low-cost system. The differences observed in the muscle response according to gender and age were notable when passengers are warned. Gender differences were more significant in the post-braking phase. When passengers were relaxed, subjects older than 35 registered higher sEMG values. Meanwhile, when passengers contract their muscles, subjects who were younger than or equal to 35 years old experienced an increment in the values of the sEMG signals

Study of the Emergency Braking Test with an Autonomous Bus and the sEMG Neck Response by Means of a Low-Cost System

This article belongs to the Special Issue Development of Innovative Sensor Platforms for Field AnalysisNowadays, due to the advances and the increasing implementation of the autonomous braking systems in vehicles, the non-collision accident is expected to become more common than a crash when a sudden stop happens. The most common injury in this kind of accident is whiplash or cervical injury since the neck has high sensitivity to sharp deceleration. To date, biomechanical research has usually been developed inside laboratories and does not entirely represent real conditions (e.g., restraint systems or surroundings of the experiment). With the aim of knowing the possible neck effects and consequences of an automatic emergency braking inside an autonomous bus, a surface electromyography (sEMG) system built by low-cost elements and developed by us, in tandem with other devices, such as accelerometers or cameras, were used. Moreover, thanks to the collaboration of 18 participants, it was possible to study the non-collision effects in two different scenarios (braking test in which the passenger is seated and looking ahead while talking with somebody in front of him (BT1) and, a second braking test where the passenger used a smartphone (BT2) and nobody is seated in front of him talking to him). The aim was to assess the sEMG neck response in the most common situations when somebody uses some kind of transport in order to conclude which environments are riskier regarding a possible cervical injury

Educational Resources for Self-learning of Descriptive Geometry

Proceeding of: 2nd International Symposium on the Education and Mechanism and Machine Science (ISEMMS 2017), 23-24 November 2017, Leganés, Madrid.In this work, two educational resources for self-learning of Descriptive Geometry are presented: the “Zero Course” and the “Support Course”. The creation of this e-learning material responds to the need that our students at University Carlos III de Madrid have to reach a minimum level at the beginning (Zero Course), and during (Support Course) the first course on technical drawing. First, the need is made out through results of surveys carried out in previous years. Then, some e-learning applications are exposed, among which the most appropriate to the need are chosen. Finally, the designed courses are described including all the technical resources. The results of the surveys carried out on the students of these courses, as well as some statistics of their qualifications, are also presented.Publicad

Treatment with tocilizumab or corticosteroids for COVID-19 patients with hyperinflammatory state: a multicentre cohort study (SAM-COVID-19)

Objectives: The objective of this study was to estimate the association between tocilizumab or corticosteroids and the risk of intubation or death in patients with coronavirus disease 19 (COVID-19) with a hyperinflammatory state according to clinical and laboratory parameters. Methods: A cohort study was performed in 60 Spanish hospitals including 778 patients with COVID-19 and clinical and laboratory data indicative of a hyperinflammatory state. Treatment was mainly with tocilizumab, an intermediate-high dose of corticosteroids (IHDC), a pulse dose of corticosteroids (PDC), combination therapy, or no treatment. Primary outcome was intubation or death; follow-up was 21 days. Propensity score-adjusted estimations using Cox regression (logistic regression if needed) were calculated. Propensity scores were used as confounders, matching variables and for the inverse probability of treatment weights (IPTWs). Results: In all, 88, 117, 78 and 151 patients treated with tocilizumab, IHDC, PDC, and combination therapy, respectively, were compared with 344 untreated patients. The primary endpoint occurred in 10 (11.4%), 27 (23.1%), 12 (15.4%), 40 (25.6%) and 69 (21.1%), respectively. The IPTW-based hazard ratios (odds ratio for combination therapy) for the primary endpoint were 0.32 (95%CI 0.22-0.47; p < 0.001) for tocilizumab, 0.82 (0.71-1.30; p 0.82) for IHDC, 0.61 (0.43-0.86; p 0.006) for PDC, and 1.17 (0.86-1.58; p 0.30) for combination therapy. Other applications of the propensity score provided similar results, but were not significant for PDC. Tocilizumab was also associated with lower hazard of death alone in IPTW analysis (0.07; 0.02-0.17; p < 0.001). Conclusions: Tocilizumab might be useful in COVID-19 patients with a hyperinflammatory state and should be prioritized for randomized trials in this situatio

La renovación de la palabra en el bicentenario de la Argentina : los colores de la mirada lingüística

El libro reúne trabajos en los que se exponen resultados de investigaciones presentadas por investigadores de Argentina, Chile, Brasil, España, Italia y Alemania en el XII Congreso de la Sociedad Argentina de Lingüística (SAL), Bicentenario: la renovación de la palabra, realizado en Mendoza, Argentina, entre el 6 y el 9 de abril de 2010. Las temáticas abordadas en los 167 capítulos muestran las grandes líneas de investigación que se desarrollan fundamentalmente en nuestro país, pero también en los otros países mencionados arriba, y señalan además las áreas que recién se inician, con poca tradición en nuestro país y que deberían fomentarse. Los trabajos aquí publicados se enmarcan dentro de las siguientes disciplinas y/o campos de investigación: Fonología, Sintaxis, Semántica y Pragmática, Lingüística Cognitiva, Análisis del Discurso, Psicolingüística, Adquisición de la Lengua, Sociolingüística y Dialectología, Didáctica de la lengua, Lingüística Aplicada, Lingüística Computacional, Historia de la Lengua y la Lingüística, Lenguas Aborígenes, Filosofía del Lenguaje, Lexicología y Terminología

Influence of anodized depth on fatigue life for bicycle cranks

Bicycle manufacturers are using new materials in order to improve the bicycle performance. In high-level cycling, magnesium, aluminum, titanium and carbon fiber, have replaced steel with the purpose of improving the weight/rigidity ratio. Due to cost factors and ease of machining, aluminum is widely used in bicycle cranks manufacturing. In order to improve the external aspect of the final product and protect the external surface of the component, some surface treatments must be applied. In the case of aluminum, anodizing is the most extended treatment, due to several factors as low cost, visual aspect, variety of colors and finishing. However, this treatment may reduce the fatigue resistance of the component. In this work, the best compromise between anodizing depth and fatigue resistance performance of a bicycle crank has been analysed in order to provide an optimum solution to improve the performance of the component

Is the use of a low-cost sEMG sensor valid to measure muscle fatigue?

Injuries caused by the overstraining of muscles could be prevented by means of a system which detects muscle fatigue. Most of the equipment used to detect this is usually expensive. The question then arises whether it is possible to use a low-cost surface electromyography (sEMG) system that is able to reliably detect muscle fatigue. With this main goal, the contribution of this work is the design of a low-cost sEMG system that allows assessing when fatigue appears in a muscle. To that aim, low-cost sEMG sensors, an Arduino board and a PC were used and afterwards their validity was checked by means of an experiment with 28 volunteers. This experiment collected information from volunteers, such as their level of physical activity, and invited them to perform an isometric contraction while an sEMG signal of their quadriceps was recorded by the low-cost equipment. After a wavelet filtering of the signal, root mean square (RMS), mean absolute value (MAV) and mean frequency (MNF) were chosen as representative features to evaluate fatigue. Results show how the behaviour of these parameters across time is shown in the literature coincides with past studies (RMS and MAV increase while MNF decreases when fatigue appears). Thus, this work proves the feasibility of a low-cost system to reliably detect muscle fatigue. This system could be implemented in several fields, such as sport, ergonomics, rehabilitation or human-computer interactions