A simple algorithm for the estimation of road traffic space mean speeds from data available to most management centres

[Abstract:] The control of the evolution of road traffic streams is highly related to productivity, safety, sustainability and, even, comfort. Although, nowadays, the findings from research efforts and the development of new technologies enable accurate traffic forecasts in almost any conditions, these calculations are usually limited by the data and the equipment available. Most traffic management centres depend on the data provided, at best, by double-loop detectors. These loops supply time means over different aggregation periods, which are indiscriminately used as the bases for subsequent estimations. Since space mean speeds are those needed in most applications (note the fundamental relationship between flow and density in traffic flow theory), most current practice begins with an error. This paper introduces a simple algorithm that the allows estimation of space mean speeds from the data provided by the loops without the need for any additional financial outlay, as long as the traffic in each time interval of aggregation is stationary and its speed distribution is log-normal. Specifically, it is focused on the calculation of the variance of the speeds with regard to the time mean, thus making possible to use the relationship between time mean speeds and space mean speeds defined by Rakha (2005). The results obtained with real data show that the algorithm behaves well if the calculation conditions help fulfil the initial hypotheses. The primary difficulties arise with transient traffic and, in this case, other specific methodologies should be used. Data fusion seems promising in this regard. Nevertheless, it cannot be denied that the improvement provided by the algorithm turns out to be highly beneficial both when used alone in the case of stationarity or as a part of a fusion

Mechanistic-empirical pavement design guide : características y elementos distintivos

[Abstract] This paper is aimed at describing the most distinctive features of the pavement design method known as Mechanistic-Empirical Pavement Design Guide and to compare it with other renowned methodologies, while emphasizing its advantages and disadvantages. The MEPDG can accurately predict damage evolution, thus helping to choose the most appropriate design for new pavements or to schedule the conservation of the already existing ones. After analyzing different pavement design and management methods, the MEPDG stands out as the most comprehensive one as it takes into account and properly combines the greatest number of factors that affect the pavement. Therefore, some countries outside the USA have already imported and calibrated this method, what, at the same time, allows the scientific community to carry out comparative studies and improve its small deficiencies.[Resumen] El objetivo de este artículo es describir los rasgos más característicos del método de diseño de firmes conocido como Mechanistic-Empirical Pavement Design Guide, así como compararlo con otras metodologías de renombre, destacando sus ventajas y desventajas. El MEPDG puede predecir con precisión la evolución de los deterioros, ayudando por tanto a elegir el diseño más adecuado para el caso de firmes de nueva construcción, o a programar la conservación de los ya existentes. Tras analizar diferentes métodos de diseño y gestión de firmes, el MEPDG destaca como el más completo al ser el que tiene en cuenta un mayor número de factores que afectan al firme. Por ello algunos países fuera de EEUU ya han importado y calibrado este método, lo que al mismo tiempo permite a la comunidad científica llevar a cabo estudios comparativos y mejorar sus pequeñas deficiencias

Osseous paleopathologies of Bonapartesaurus rionegrensis (Ornithopoda, Hadrosauridae) from Allen Formation (Upper Cretaceous) of Patagonia Argentina

The paleopathological record provides relevant information about paleobiology and paleoecology of fossil organisms. Based on the information obtained from paleopathologies, it is possible to infer how these injuries affected inter- and intraspecific relationships among organisms, and their interaction with the environment. For instance, fractures and infections may affect their behavior, such as locomotion, strength, and stamina, leading in some cases to death. Here, we describe the injuries recorded in the hadrosaurid Bonapartesaurus rionegrensis and their possible implications in its paleobiology. Three pathologies have been identified, two in caudal vertebrae neural spines and the third in the left metatarsal II. The caudal vertebra MPCA-Pv SM2/17 presents a displaced fracture with an advanced stage of healing and probably related to a trauma. The caudal vertebra MPCA-Pv SM2/19 shows an almost fully healed fracture produced by an impact or stress event. Finally, in the metatarsal II there is an overgrowth of pathological bone that covers the shaft interpreted as probably a neoplasm (e.g., osteosarcoma). The suite of vertebral paleopathologies would have generated pain and discomfort during its daily activity.Fil: Cruzado Caballero, Penélope. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación en Paleobiología y Geología; Argentina. Universidad de La Laguna; España. Universidad de Zaragoza; EspañaFil: Lecuona, Agustina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación en Paleobiología y Geología; ArgentinaFil: Cerda, Ignacio Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación en Paleobiología y Geología; Argentina. Museo Provincial “Carlos Ameghino”; ArgentinaFil: Díaz Martínez, Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación en Paleobiología y Geología; Argentin

Autonomous driving: a bird's eye view

[Abstract:] The introduction of autonomous vehicles (AV) will represent a milestone in the evolution of transportation and personal mobility. AVs are expected to significantly reduce accidents and congestion, while being economically and environmentally beneficial. However, many challenges must be overcome before reaching this ideal scenario. This study, which results from on-site visits to top research centres and a comprehensive literature review, provides an overall state-of-the-practice on the subject and identifies critical issues to succeed. For example, although most of the required technology is already available, ensuring the robustness of AVs under all boundary conditions is still a challenge. Additionally, the implementation of AVs must contribute to the environmental sustainability by promoting the usage of alternative energies and sustainable mobility patterns. Electric vehicles and sharing systems are suitable options, although both require some refinement to incentivise a broader range of customers. Other aspects could be more difficult to resolve and might even postpone the generalisation of automated driving. For instance, there is a need for cooperation and management strategies geared towards traffic efficiency. Also, for transportation and land-use planning to avoid negative territorial and economic impacts. Above all, safe and ethical behaviour rules must be agreed upon before AVs hit the road.Ministerio de Economía y Competitividad; TRA2016-79019-R/COO

Technology: a necessary but not sufficient condition for future personal mobility

Número especial: Sustainable Road Transportation Planning[Abstract:] Technological advances revolutionize industrial processes, science, communications, and our way of life. However, developed societies have reached a stage in which the fascination with technological innovations often results in their indiscriminate consumption. In this paper, road traffic is used as a line of argument to demonstrate that the random introduction of technology does not imply benefits to society. Particularly, it is analyzed why some of the potential benefits of technological progress are lost in fields such as traffic monitoring, data handling, and traffic management, or in sustainable mobility initiatives, such as the introduction of electric vehicles or the implementation vehicle sharing projects. The risks faced in the future advent of autonomous vehicles are also discussed, and ideas for improvement suggested. A critical reflection on other transportation modes that are expected to be realized in the near future is included as well. The performed analysis evidences that the potential improvement in personal mobility will not become a reality if it exclusively relies on the latest technological devices, in line with consumers’ fantasies or economic interests. This is a statement that could be generalized to many other fields. The implementation/consumption of a particular technology should not be an objective in itself, but a tool to bring benefits to society.Ministerio de Economía y Competitividad; TRA2016-79019-R/COO

Compensación de los errores de alineación provocados por las deflexiones de los ejes en transmisiones de engranajes cónicos espirales diseñadas con distintos tipos de huella de contacto

[SPA] En el presente trabajo se analiza una metodología para compensar los errores de alineación debidos a las deflexiones de los ejes en transmisiones de engranajes cónicos espirales cuando se transmite una carga nominal o de diseño, considerando cuatro tipos de patrones de contacto: lineal, localizado en la dirección longitudinal, localizado en la dirección del perfil, y localizado en una dirección ajustada diagonal. Para ello se determinan en primer lugar los parámetros de máquina correspondientes al proceso Cyclo-Palloid que permiten diseñar dichos patrones de contacto. A continuación se aplica un proceso iterativo en cada uno de los cuatro diseños. Este proceso iterativo requiere analizar, en cada etapa del proceso, la transmisión con ejes mediante el método de los elementos finitos, para obtener los errores de alineación debidos a la deflexión de los ejes. Los resultados muestran la eficacia de la metodología propuesta para compensar, desde el diseño de las geometrías de las superficies de contacto, las deflexiones de los ejes en los cuatro tipos de patrones de contacto, así como la mayor tolerancia de los diseños con contacto localizado en la dirección del perfil y en la dirección diagonal ajustada a variaciones de la carga de diseño. Se presentan varios ejemplos numéricos. [ENG] In this paper, a methodology to compensate alignment errors due to shaft deflections for a given design load in spiral bevel gear drives is presented, considering four types of contact pattern, linear and localized in longitudinal, profile and adjusted diagonal directions. Firstly, the machine-tool settings corresponding to a Cyclo-Palloid process are determined to design the mentioned four contact patterns. Secondly, an iterative process for each contact design is required where a finite element analysis provides the alignment errors due to shaft deflections. The results show the efficency of the proposed methodology to compensate alignment errors from the design of the gear tooth surfaces in the four types of contact pattern, and the larger tolerance in the profile and adjusted diagonal directions designs to variations of the design load. Several numerical examples are presented

Morphological variations in bipedal dinosaur tracks from the Aguada de Tuco tracksite, Candeleros Formation (Cenomanian, Upper Cretaceous) of northwestern Patagonia, Argentina

New bipedal dinosaur tracks from the Aguada de Tuco tracksite of the Cenomanian Candeleros Formation (Neuquén Group, Neuquén Basin, Argentina) are reported here. These tracks are preserved in medium grain-sized sandstones from fluvial deposits in three different stratigraphic levels (Level 1-3). The Level 1 comprises deep tridactyl tracks with apparent metatarsal impressions (average length of 31 cm) preserved as true tracks and undertracks, perhaps generated due to simply sinking of the pes into a soft substrate. The Level 2 includes large tridactyl tracks (average length of 58 cm) found a few meters close to a previously studied sauropod trackway. These bipedal and quadrupedal large tracks differ in several preservational features probably due to differences in the pedal shape and substrate interaction between these trackmakers. Level 3 comprises small to large tridactyl tracks (length from 6 to 34 cm) with a broad variety of morphologies including intra-trackway variation, suggesting changes in the substrate properties, mainly moisture content, along the tracking surface. Considering that the footprints studied here are poorly preserved, they were not assigned to any particular ichnotaxon. The large tridactyl tracks were attributed to theropod trackmakers while medium and small tracks to undetermined bipedal dinosaurs. This tracksite exemplifies inter- and intra-trackways morphological variability of dinosaur tridactyl tracks controlled mainly by the substrate properties.Fil: Heredia, Arturo Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; ArgentinaFil: Pazos, Pablo Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; ArgentinaFil: Díaz Martínez, Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación en Paleobiología y Geología; Argentina1° Reunión Virtual de Comunicaciones de la Asociación Paleontológica ArgentinaBuenos AiresArgentinaAsociación Paleontológica Argentin

Analysis of substrate variations related to dinosaur track preservation from the Aguada de Tuco area, Candeleros Formation (Cenomanian), Neuquén Basin, Argentina

Fossil tracks provide direct information of the activity of a trackmaker during the interaction with the substrate. Track morphology can exhibit differences as a response to changes in substrate physical parameters like humidity, grain-size and sediment composition, as well as response to the limb dynamics and foot anatomy of the trackmaker. Recently, several dinosaur tracks with different preservational variants were found in a tracksite under study of the Candeleros Formation (Aguada de Tuco). An unusual narrow-gauge sauropod trackway preserved in fine-grained sandstones from floodplain deposits was documented. Each left track shows bulky and high (vertical) rims, significantly larger than the right ones. Thus a different substrate property between them is envisaged. These bulky rims also show well-preserved and non-deformed ripples on the top, suggesting a moist underlying substrate but with a dried or stabilised top that was only displaced upward during the track formation. The same stratigraphic surface contains a set of three extended tridactyl trackways, deeply impressed with no variation in the morphology of each track. In consequence no changes in substrate properties are interpreted between them. However, some discontinuous and shallow sauropod tracks were produced before the tridactyl trackways as they are overimprinted. Interestingly, 10 m apart a cluster of theropod trackways exhibit larger and shallower tracks than the previous one, which indicate a more consistent substrate, considering that they correspond to larger producers in the last case. In conclusion, the general track morphology is mainly conditioned by changes in substrate consistency over time in the same area.Fil: Heredia, Arturo Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; ArgentinaFil: Pazos, Pablo Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; ArgentinaFil: Díaz Martínez, Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación en Paleobiología y Geología; ArgentinaReunión de Comunicaciones de la Asociación Paleontológica ArgentinaPuerto MadrynArgentinaAsociación Paleontológica Argentin