673 research outputs found
Experimental evidence supporting simpler Action Point paradigms for car-following
No full textThe Action Point theory is one of the paradigms that can be applied to understand and reproduce car-following behaviour. Several different approaches to this theory have been proposed, some more simple and others more complex. In particular, the reference point in this field is still the paradigm from Wiedemann, which requires the identification of four action-point thresholds. In this paper we review Action Point theories in order to highlight similarities and differences and to ascertain whether all the thresholds proposed by Wiedemann actually bind the driving behaviour. Based on a large-scale experiment in which car-following data were collected, we identified all candidate action points assuming that the more complex (four-threshold) theory holds. Then we tested these points with respect to the large data set of available observations, in order to check whether actual actions are performed at the points. The results show that very often simpler approaches better match the observed data and that in order to explain car-following behaviour it is sufficient in most cases to refer to two thresholds. The results obtained by real-world observation were also tested in virtual environments (two different kinds of driving simulators) and were confirmed
Validation of driving behaviour as a step towards the investigation of Connected and Automated Vehicles by means of driving simulators
No full textConnected and Automated Vehicles (CAVs) are likely to become an integral part of the traffic stream within the next few years. Their presence is expected to greatly modify mobility behaviours, travel demands and habits, traffic flow characteristics, traffic safety and related external impacts. Tools and methodologies are needed to evaluate the effects of CAVs on traffic streams, as well as the impact on traffic externalities. This is particularly relevant under mixed traffic conditions, where human-driven vehicles and CAVs will interact. Understanding technological aspects (e.g. communication protocols, control algorithms, etc.) is crucial for analysing the impact of CAVs, but the modification induced in human driving behaviours by the presence of CAVs is also of paramount importance. For this reason, the definition of appropriate CAV investigations methods and tools represents a key (and open) issue. One of the most promising approaches for assessing the impact of CAVs is operator in the loop simulators, since having a real driver involved in the simulation represents an advantageous approach. However, the behaviour of the driver in the simulator must be validated and this paper discusses the results of some experiments concerning car-following behaviour. These experiments have included both driving simulators and an instrumented vehicle, and have observed the behaviours of a large sample of drivers, in similar conditions, in different experimental environments. Similarities and differences in driver behaviour will be presented and discussed with respect to the observation of one important quantity of car-following, the maintained spacing
On some properties of singular matrices
No full textAbstractSome results of Ostrowski in [5] are generalized to the case of monotonic norms
Surveying the open podcast landscape and finding our niche: Blog #1 for the Open Podcasting Project
No full textblog post#GO--GN Fellowshiphttps://go-gn.net/gogn/the-third-call-for-go-gn/Open educational practices (OEP)Student perspectivesOpen researchpodcast creatio
Introducing the "Into the Open" podcast series
No full textblog post#GO--GN Fellowshiphttps://go-gn.net/gogn/the-third-call-for-go-gn/Open Educational Practices (OEP)Student perspectivesOpen researchPodcast creatio
Small points on subvarieties of a torus
No full textLet V be a subvariety of a torus defined over the algebraic numbers. We give a qualitative and quantitative description of the set of points of V of height bounded by invariants associated to any variety containing V . Especially, we determine whether such a set is or is not dense in V . We then prove that these sets can always be written as the intersection of V with a finite union of translates of tori of which we control the sum of the degrees. As a consequence, we prove a conjecture by the first author and David up to a logarithmic factor
Altura de la rama mandibular y su relación con el ángulo SN GO-GN en radiografías cefálicas laterales digitales
No full textObjetivo: El presente estudio de investigación tiene como objetivo establecer la altura de la rama mandibular y su relación con el ángulo SN Go-Gn en radiografías cefálicas laterales digitales en pacientes de 18 a 45 años de edad de la ciudad de Cuenca-Ecuador. Materiales y Métodos: Este estudio, cuantitativo, observacional con un enfoque correlacional, se realizó en radiografías cefálicas laterales digitalizadas que reposan en el archivo de un centro radiológico de la ciudad de Cuenca - Ecuador e incluyó un total de 388 radiografías laterales escogidas bajo ciertos criterios de inclusión y exclusión. Las variables analizadas fueron altura de la rama mandibular, ángulo SN Go-Gn y sexo. Las medidas se realizaron, aplicando el software AUTOCAD 2018, por un examinador entrenado previamente para tal fin, y validados posteriormente por la autora del estudio. Los datos obtenidos de las diferentes mediciones fueron registrados en una hoja de cálculo Excel. Para evaluar la relación entre la altura de la rama mandibular y el ángulo SN Go-Gn se empleó el coeficiente de correlación r de Pearson, para la interpretación se siguió la sugerencia de Cohen (1988); correlación nula (0.00 ≤ r <0.10), correlación leve (0.10 ≤ r <0.30), correlación moderada (0.30 ≤ r <0.50) y correlación fuerte (0.50 ≤ r < 1). Para la comparación se empleó el estadístico paramétrico t-Student, la significancia considerada fue de 0.01 (p<0.01). El procesamiento de datos fue realizado en el programa estadístico SPSS V27. Resultados: Se encontró una correlación negativa fuerte, entre la altura de la rama mandibular y el ángulo SN Go-Gn (r= -0.535; p<0.001), lo que implica que a mayor altura (mm), menor ángulo (°) Conclusión: Los resultados mostraron que si existe relación entre la altura de la rama mandibular y el ángulo SN Go-Gn, en pacientes de 18 a 45 años de edad.The present research study aims to establish the height of the mandibular ramus and its relationship with the SN Go-Gn angle in digital lateral cephalic radiographs in patients from 18 to 45 years old from the city of Cuenca-Ecuador. Materials and Methods: This study, quantitative, observational with a correlational approach, was carried out on digitalized lateral cephalic radiographs that rest in the archive of a radiological center in the city of Cuenca - Ecuador and included a total of 388 lateral radiographs chosen under certain criteria of inclusion and exclusion. The variables analyzed were mandibular ramus height, SN Go-Gn angle, and sex. The measurements were made, applying the AUTOCAD 2018 software, by an examiner previously trained for this purpose, and subsequently validated by the author of the study. The data obtained from the different measurements were recorded in an Excel spreadsheet. To evaluate the relationship between the height of the mandibular ramus and the SN Go-Gn angle, the Pearson r correlation coefficient was used, for the interpretation the suggestion of Cohen (1988) was followed; null correlation (0.00 ≤ r <0.10), slight correlation (0.10 ≤ r <0.30), moderate correlation (0.30 ≤ r <0.50) and strong correlation (0.50 ≤ r < 1). For the comparison, the parametric t-Student statistic was used, the significance considered was 0.01 (p<0.01). The data processing was carried out in the statistical program SPSS V27. Results: A strong negative correlation was found between the height of the mandibular ramus and the SN Go-Gn angle (r= -0.535; p<0.001), which implies that the higher the height (mm), the lower the angle (°). Conclusion: The results showed that there is a relationship between the height of the mandibular ramus and the SN Go-Gn angle, in patients from 18 to 45 years old.
Key words: mandibular Ramus, mandibular growth0000-0002-3794-1942Especialista en OrtodonciaCuenc
Longitudinal control behaviour: Analysis and modelling based on experimental surveys in Italy and the UK
No full textThis paper analyses driving behaviour in car-following conditions, based on extensive individual vehicle data collected during experimental field surveys carried out in Italy and the UK. The aim is to contribute to identify simple evidence to be exploited in the ongoing process of driving assistance and automation which, in turn, would reduce rear-end crashes. In particular, identification of differences and similarities in observed car-following behaviours for different samples of drivers could justify common tuning, at a European or worldwide level, of a technological solution aimed at active safety, or, in the event of differences, could suggest the most critical aspects to be taken into account for localisation or customisation of driving assistance solutions. Without intending to be exhaustive, this paper moves one step in this direction. Indeed, driving behaviour and human errors are considered to be among the main crash contributory factors, and a promising approach for safety improvement is the progressive introduction of increasing levels of driving automation in next-generation vehicles, according to the active/preventive safety approach. However, the more advanced the system, the more complex will be the integration in the vehicle, and the interaction with the driver may sometimes become unproductive, or risky, should the driver be removed from the driving control loop. Thus, implementation of these systems will require the interaction of human driving logics with automation logics and then an enhanced ability in modelling drivers' behaviour. This will allow both higher active-safety levels and higher user acceptance to be achieved, thus ensuring that the driver is always in the control loop, even if his/her role is limited to supervising the automatic logic. Currently, the driving mode most targeted by driving assistance systems is longitudinal driving. This is required in various driving conditions, among which car-following assumes key importance because of the huge number of rear-end crashes. The increased availability of lower-cost information and communication technologies (ICTs) has enhanced the possibility of collecting copious and reliable car-following individual vehicle data. In this work, data collected from three different experiments, two carried out in Italy and one in the UK, are analysed and compared. The experiments involved 146 drivers (105 Italian drivers and 41 UK drivers). Data were collected by two instrumented vehicles. Our analysis focused on inter-vehicular spacing in equilibrium car-following conditions. We observed that (i) the adopted equilibrium spacing can be fitted using lognormal distributions, (ii) the adopted equilibrium spacing increases with speed, and (iii) the dispersion between drivers increases with speed. In addition, according to different headway thresholds (up to 1 second) a significant number of potentially dangerous behaviours is observed. Three different car-following paradigms are also applied to each of the experiments, and modelling parameters are calibrated and compared to obtain indirect confirmation about the observed similarities and differences in driving behaviour
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