Improving safety of runway overrun through the correct numerical evaluation of rutting in Cleared and Graded Areas

Aircraft overrun is potentially very dangerous to human life. Statistics show that overrun is mainly due to human errors causing loss of control in wheel alignment, high approach speed, and long touchdown. To prevent such disastrous consequences, advanced material arresting systems are currently being used in the main international airports for construction of Runway Safety Areas (RSAs). Many predictive models have been developed for controlling overrun events: the early reliable numerical models, on the basis of theoretical streamlined assumptions, were gradually replaced. More rigorous models based on Multibody System (MBS) and Finite Element Method (FEM) theories are nowadays much more preferred. These are characterized by high levels of reliability, even though the large number of data required does not always allow an exhaustive description of the domain of analysis. The paper presents an alternative method for predicting rut depths induced by aircraft overrunning. Such method is based on a numerical streamlined model, integrated with measurements from Light Falling Weight Deflectometer (LFWD), to define, section by section, the mechanical properties of soils in Cleared and Graded Areas (CGAs). The method has been validated through in situ tests, showing its high effectiveness and efficiency

GPR applications for geotechnical stability of transportation infrastructures

Nowadays, severe meteorological events are always more frequent all over the world. This causes a strong impact on the environment such as numerous landslides, especially in rural areas. Rural roads are exposed to an increased risk for geotechnical instability. In the meantime, financial resources for maintenance are certainly decreased due to the international crisis and other different domestic factors. In this context, the best allocation of funds becomes a priority: efficiency and effectiveness of plans and actions are crucially requested. For this purpose, the correct localisation of geotechnically instable domains is strategic. In this paper, the use of Ground-Penetrating Radar (GPR) for geotechnical inspection of pavement and sub-pavement layers is proposed. A three-step protocol has been calibrated and validated to allocate efficiently and effectively the maintenance funds. In the first step, the instability is localised through an inspection at traffic speed using a 1-GHz GPR horn launched antenna. The productivity is generally about or over 300 Km/day. Data are processed offline by automatic procedures. In the second step, a GPR inspection restricted to the critical road sections is carried out using two coupled antennas. One antenna is used for top pavement inspection (1.6 GHz central frequency) and a second antenna (600 MHz central frequency) is used for sub-pavement structure diagnosis. Finally, GPR data are post-processed in the time and frequency domains to identify accurately the geometry of the instability. The case study shows the potentiality of this protocol applied to the rural roads exposed to a landslide

Server resource dimensioning and routing of service function chain in NFV network architectures

The Network Function Virtualization (NFV) technology aims at virtualizing the network service with the execution of the single service components in Virtual Machines activated on Commercial-off-the-shelf (COTS) servers. Any service is represented by the Service Function Chain (SFC) that is a set of VNFs to be executed according to a given order. The running of VNFs needs the instantiation of VNF instances (VNFI) that in general are software components executed on Virtual Machines. In this paper we cope with the routing and resource dimensioning problem in NFV architectures. We formulate the optimization problem and due to its NP-hard complexity, heuristics are proposed for both cases of offline and online traffic demand. We show how the heuristics works correctly by guaranteeing a uniform occupancy of the server processing capacity and the network link bandwidth. A consolidation algorithm for the power consumption minimization is also proposed. The application of the consolidation algorithm allows for a high power consumption saving that however is to be paid with an increase in SFC blocking probability

APRENDIZAJE BASADO EN PROBLEMAS ESTRATEGIA METODOLOGICA EN LA ENSEÑANZA DE LA ODONTOLOGIA

La enseñanza implica la generación de vínculos entre sujetos y conocimientos a través de estrategias que los articulen y que posibiliten promover el aprendizaje. Podemos afirmar que la enseñanza tiene una dimensión metodológica fundamental. Es decir que quien enseña tiene que resolver la manera de hacerlo, un modo de proceder, y delimitar un hacer desde una racionalidad que le da sentido A lo largo de la historia se han delineado diferentes maneras de concebir la enseñanza de acuerdo a su función social, la naturaleza del conocimiento, los procesos subjetivos del aprendizaje, entre otros. La pregunta por la "resolución metodológica" que siempre nos hacemos una vez que hemos resuelto el sentido o las finalidades y delimitado los contenidos: ¿Cómo lo "trabajo"? ¿Qué hago en clase? ¿Qué les propongo a mis alumnos que hagan?. Como sostiene Díaz Barriga lo metodológico implica una articulación entre una dimensión epistemológica objetiva (los saberes) y una dimensión epistemológica subjetiva (los procesos de aprendizaje de los alumnos). De modo que cada tarea que se propone a los alumnos propicia un tipo de relación con el saber. Daniel Prieto Castillo denomina prácticas de aprendizaje a aquellas posibles actividades que pueden plantearse para el trabajo con los alumnos y las organiza en siete tipos diferentes según los procesos de aprendizaje o de conocimiento que las mismas implican para los alumnos.La definición de estrategias de trabajo con los alumnos, implican maneras concretas de intervenir para organizar la acción, para estructurarla. De este modo, se da lugar al desarrollo de espacios de trabajo en torno al conocimiento, de manera que signifiquen para los alumnos, experiencias de aprendizaje. El trabajo con el análisis de casos, los trabajos de indagación en terreno, la elaboración de un producto, la resolución de problemas, la simulación de situaciones, los trabajos de campo, constituyen algunos ejemplos de estas estrategias.En este caso y desde esta mirada sobre lo educativo es que se considera que construir la tarea de enseñanza a partir de la estrategia del "aprendizaje basado en problemas" es una instancia válida y enriquecedora

Mapping the spatial variation of soil moisture at the large scale using GPR for pavement applications

The characterization of shallow soil moisture spatial variability at the large scale is a crucial issue in many research studies and fields of application ranging from agriculture and geology to civil and environmental engineering. In this framework, this work contributes to the research in the area of pavement engineering for preventing damages and planning effective management. High spatial variations of subsurface water content can lead to unexpected damage of the load-bearing layers; accordingly, both safety and operability of roads become lower, thereby affecting an increase in expected accidents. A pulsed ground-penetrating radar system with ground-coupled antennas, i.e., 600-MHz and 1600-MHz center frequencies of investigation, was used to collect data in a 16 m × 16 m study site in the Po Valley area in northern Italy. Two ground-penetrating radar techniques were employed to non-destructively retrieve the subsurface moisture spatial profile. The first technique is based on the evalu¬ation of the dielectric permittivity from the attenuation of signal amplitudes. Therefore, dielectrics were converted into moisture values using soil-specific coefficients from Topp’s relationship. Ground-penetrating-radar-derived values of soil moisture were then compared with measurements from eight capacitance probes. The second technique is based on the Rayleigh scattering of the signal from the Fresnel theory, wherein the shifts of the peaks of frequency spectra are assumed comprehensive indi¬cators for characterizing the spatial variability of moisture. Both ground-penetrating radar methods have shown great promise for mapping the spatial variability of soil moisture at the large scale

Automatic best wireless network selection based on key performance indicators

Introducing cognitive mechanisms at the application layer may lead to the possibility of an automatic selection of the wireless network that can guarantee best perceived experience by the final user. This chapter investigates this approach based on the concept of Quality of Experience (QoE), by introducing the use of application layer parameters, namely Key Performance Indicators (KPIs). KPIs are defined for different traffic types based on experimental data. A model for an ap- plication layer cognitive engine is presented, whose goal is to identify and select, based on KPIs, the best wireless network among available ones. An experimenta- tion for the VoIP case, that foresees the use of the One-way end-to-end delay (OED) and the Mean Opinion Score (MOS) as KPIs is presented. This first implementation of the cognitive engine selects the network that, in that specific instant, offers the best QoE based on real captured data. To our knowledge, this is the first example of a cognitive engine that achieves best QoE in a context of heterogeneous wireless networks