1,721,118 research outputs found
Innovative monitoring instruments as support tools for natural risks management
No full textWithin the geotechnical field, monitoring systems are particularly important for what concern the description of natural phenomena and data collection for risks prevention purposes. For this reason, the need for instruments able to guarantee a continuous and prolonged control of the area has led to the development of new monitoring systems featuring higher reliability, durability and accuracy with respect to traditional approaches. With these tools, it is possible to monitor various parameters with automatic procedures and high frequency sampling, allowing to perform statistical analyses and to provide a more accurate description of the ongoing phenomenon. Another relevant aspect is the ability to realize automated systems able to remotely elaborate data recorded by on-site instrumentation. This feature has led to the development of specific software and web-based interactive platforms integrated with various technologies. These features made it possible to develop Early Warning Systems (EWS) with a near real-time approach, allowing for a more effective and reliable management of emergencies
Landslide time-of-failure forecast and alert threshold assessment: A generalized criterion
Full text linkThe forecast of a landslide's time of failure and the definition of alert thresholds are fundamental aspects in the study of natural hazards. However, these tasks are particularly difficult due to the large number of parameters and factors involved, and are therefore usually performed with a site-specific approach. This work describes an attempt to generalize the behavior of a landslide approaching collapse, with particular attention to the definition of a general criterion to define alert thresholds. The procedure started with the creation of a database of displacement data recorded for historical landslides, then the inverse velocity model was applied to these datasets to evaluate the time of failure under the assumption of linear behavior during the accelerating phase. A model calibration was conducted to best describe the monitored data and highlight any non-linear trend. A curve describing the velocity versus time relationship was then computed for each single slope failure case using the parameter obtained through this operation. In the final step of the study, these curves were processed with a normalization procedure, thus obtaining a dimensionless velocity-related coefficient. This parameter allowed the comparison of different landslide datasets on a single graph, which can be used as a general reference to define alert thresholds for emergency purposes. In order to test the criterion's ability to represent landslide behavior, the procedure was also applied to a different case by simulating progressive data acquisition
Digital Terrain Model Geospatial Modelling
Full text linkThe modelling means the world object cognition based on the analogy. This analogy presents an idea and material imitation of some properties of the existing world. It is processed by various anthropogenic objects, in which the chosen properties are presented, defined and characterised as shapes and relations of original objects. The simplified objects are created. These objects are specially created only for world study. These types of objects are called models. To edit the digital terrain model correctly, it is necessary to understand the geospatial modelling
Impact of environmental factors on stilbene biosynthesis
Full text linkStilbenes are a small family of polyphenolic secondary metabolites that can be found in several distantly related plant species. These compounds act as phytoalexins, playing a crucial role in plant defense against phytopathogens, as well as being involved in the adaptation of plants to abiotic environmental factors. Among stilbenes, trans-resveratrol is certainly the most popular and extensively studied for its health properties. In recent years, an increasing number of stilbene compounds were subjected to investigations concerning their bioactivity. This review presents the most updated knowledge of the stilbene biosynthetic pathway, also focusing on the role of several environmental factors in eliciting stilbenes biosynthesis. The effects of ultraviolet radiation, visible light, ultrasonication, mechanical stress, salt stress, drought, temperature, ozone, and biotic stress are reviewed in the context of enhancing stilbene biosynthesis, both in planta and in plant cell and organ cultures. This knowledge may shed some light on stilbene biological roles and represents a useful tool to increase the accumulation of these valuable compounds
Alert threshold assessment based on equivalent displacements for the identification of potentially critical landslide events
Full text linkOver the past years, the growing number of natural hazards all over the world has led to an increasing focus on activities aimed at studying and controlling the occurrence of these phenomena. In this context, monitoring systems have become a fundamental component for Landslide Early Warning Systems, allowing to understand the evolution of these processes and assess the need for dedicated mitigation measures. This result is achieved thanks to several technological advancements that led to the introduction of more accurate and reliable sensors, as well as automatic procedures for data acquisition and elaboration. However, despite these improvements, the data interpretation process is still a challenging task, in particular when it comes to the identification of critical events and failure forecasting operations. This paper presents a methodology developed to assess if a potentially critical event is displaying a significant deviation from previously sampled data, or if it could be classified as a false alarm. The process relies on the definition of a threshold value based on the landslide behavior preceding the event of interest. In particular, the reference value derives from the evaluation of equivalent displacements, defined as the displacements previously observed in a time interval equal to the one showed by the potentially critical event. This paper reports a series of examples referring to different case studies, involving both false alarms and real collapses, underlining the effectiveness of the proposed model as a useful tool to evaluate the landslide behavior with a near-real-time approach
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Conceptual and numerical modelling for hydrogeological hazard assessment in the UNESCO site of Castelseprio (Northern Italy)
No full textThis paper deals with the evaluation of the hydrogeological hazard in the archaeological site of Castelseprio (northern Italy). Based on the geological, hydrogeological and geomorphological setting of the site, the failure modes and their causative factors were identified, and a proper conceptual model was reconstructed, identifying piping processes as the main phenomena ruling the slopes evolution and the landslides triggering. Afterwards, the hydrogeological hazard was assessed applying numerical modelling both in 2D and in 3D. In particular, the 2D analyses were aimed at simulating the triggering phenomena leading to instability, with particular reference to the influence of piping initiation and propagation. Numerical results in 2D showed a dependence of the stability conditions on the rainfall intensity, whose increase brings about a significant widening of the zones prone to piping. Based on the results of the 2D simulations, a 3D model was implemented in order to evaluate the stability conditions in the different zones of the study area. The results of the 3D simulations allowed mapping the hydrogeological hazard and identifying the best practices for the future development of the UNESCO site, in order to guarantee its unity as well as its safety
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