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Numerical analysis of debris-flow interaction with open barriers
No full textDebris flows are fast gravity-driven flows consisting of multiple interacting phases. Due to their rapid movement and destructive power, structural mitigation measures have become essential in order to prevent extensive damage to property and life. Among these structures, rigid barriers constitute an efficient system of mitigation, which induces sediment deposition in case of an event. The optimal design of these structures requires the impact force estimation, which has recently become a crucial issue. Because of this, numerous experimental and numerical investigations have been carried out in recent years concerning debris flow and their impact energy on rigid closed barriers. However, there is a lack of information in the framework of rigid open barriers, especially for what concerns the influence of the outlet geometry. In this regard, many studies have examined the jamming of a single-outlet silo, where the mass discharges in the direction of gravity, but the jamming of particles on an inclined slope has not been sufficiently investigated yet. The present numerical study investigates the formation of arching behind an open barrier that partially arrests the flow of particles on an inclined channel. The nature of jamming, and the impact energy on the barrier are examined using DEM simulations for a fixed discharged mass, using different outlet sizes and inclines. The applied model is an improvement of the LBM-DEM code developed by Leonardi et al.. Static friction is implemented with the spring-dashpot linear model and a directional constant torque model is included in order to describe rolling resistance due to elastic deformation and the effect of non-spherical particle shape. The resulting force and momentum at the flow base are analysed in detail together with the kinetic energy and the distribution of particles in the slit. The dynamic impact of the solid component alone is analysed in order to rationalize the design of open barriers. Indeed numerical examples show that a single outlet could jam with a probability that decreases with the slope and the outlet size, but two adjacent outlets do not necessarily jam in the same configuration
LIFE CYCLE ASSESSMENT OF A DRINKING WATER PRODUCTION SYSTEM
No full textThe main goal of water treatment is to avoid human health risks and to provide sufficient and good quality water for drinking, industrial purposes, and other economic activities by removing chemical and biological contaminants through water treatment processes. However, these processes require increasing efforts in terms of technology, chemicals and energy inputs, which translates to increased secondary environmental impacts and increased water production costs. The objective of the study is to evaluate the drinking water treatment (DWT) system in Iasi City (Romania), by means of life cycle assessment and to identify and characterize the environmental impacts, to determine the weak points of drinking water production processes. Iasi City is the most developed urban centre from Moldova Region in the North Eastern region of Romania and has a DWT system providing water in accordance with European standards. The DWT system process comprises the following stages: coagulation/flocculation with ferric chloride (or polyacrylamide and powdered activated carbon) coupled with pre-oxidation (injection of chlorine dioxide), followed by sedimentation in radial basins, pH correction with calcium hydroxide, rapid filtration on sand filters, slow filtration on granular activated carbon (GAC) filters and followed by final disinfection with chlorine gas. In this study a life cycle analysis has been applied to assess the environmental performance of Iasi DWTP for 1 m3 of potable water produced, considering the impact generated by energy consumption, technologies and reagents used. The electricity required by the different treatment stages has been accounted for the entire DWT plant, each equipment and water treatment parameters being monitored and controlled through a SCADA software. The main contributors to impact in most of the categories are the electricity consumption and the iron chloride production used in coagulation/flocculation step. The most important impact categories are the freshwater eutrophication and the freshwater and marine ecotoxicity, and the most important contributors remain electricity and iron chloride usage. The level of detail obtained for the inventory and the impact assessment steps may be used as reference for future LCA studies, analysing other water treatment plants since the climate, technological, cultural and socio-economical differences clearly define the particularities of a DWT in any context and region
EVALUATION OF SEISMIC FRAGILITY OF INFILLED REINFORCED CONCRETE FRAMES SUBJECT TO AFTERSHOCKS
No full textMasonry infills strongly interact with primary framed structures in presence of seismic loads. Depending on the regularity of the distribution in plan and over the height, and on the geometrical and mechanical properties of the infill/frame system they can reduce or amplify structural damage due to mainshocks and aftershocks. The paper presents an assessment framework to determine fragility curves of reinforced concrete bare and infilled frames subject previous earthquake induced damage. Mainshock ground motions are defined using spectrum-compatible accelerograms having return period associated with different limit states. Aftershocks are defined as spectrum compatible signals and are scaled in amplitude to different intensity levels. Incremental dynamic analysis (IDA) is carried out in OpenSees using signals composed of a fixed part (mainshock) and a variable part (aftershock). Aftershocks are varied in amplitude in order to assess the response of the pre-damaged structure to earthquakes having different intensity levels. Fragility curves are derived for bare and infilled framed structures, considering the cases of no pre-damaging, low pre-damaging, and high pre-damaging. Results show that the response of infilled frames to the aftershocks significantly depends on the damage experienced during the mainshock. For the cases of low predamaging (low-intensity mainshock) seismic response has resulted less sensitive to further shakings. Conversely, infilled frames severely damaged by mainshock achieved collapse in correspondence of intensity levels f the aftershocks significantly lower than those of the mainshoc
Modeling Li-ion batteries for automotive application: A trade-off between accuracy and complexity
No full textThis paper presents a fast and effective approach to Li-ion battery performance modeling, particularly suited for automotive applications (i.e. HEV, PHEV, BEV). A second-order electrical equivalent circuit model made up by one voltage source, one series resistor and two series RC blocks (dual-polarization model), is here selected as the best trade-off solution for the task, addressing both acceptable levels of accuracy and complexity. While a lithium-iron-phosphate cylindrical battery cell is chosen for the purpose of the study, the presented procedure has broader validity and is mostly independent of Li-ion chemistry and/or cell format. The battery model is parametrized through a low time-consuming current pulse test, performed during both charging and discharging, at different state of charge levels. The temperature and load-current effects on the battery performance are not considered for simplicity and lightness of the presented model. Validation is carried out by comparing measured and simulated results during the dynamic current pulse test, showing a high level of agreement between the two
Public and private interests in urban regeneration programs: The case study of trieste historic centre
No full textThis paper focuses on the evaluation of the economic aspects related to urban transformations, with particular attention to the relationships among the different interests involved. Starting from the application of the Discounted Cash-Flow Analysis, the study investigates public and private perspectives in the development of the regeneration of the historic center of the city of Trieste (Italy). Different scenarios are considered and evaluated from the point of view of the public and private convenience considering the Internal Rate of Return and the Net Present Value indicators. The final results are also verified by means of specific sensitivity analyses that allow the validity of the proposed model to be tested
METRIC DOCUMENTATION OF CULTURAL HERITAGE: RESEARCH DIRECTIONS FROM THE ITALIAN GAMHER PROJECT
No full textGAMHer is a collaborative project that aims at exploiting and validating Geomatics algorithms, methodologies and procedures in the framework of new European regulations, which require a more extensive and productive use of digital information, as requested by the Digital Agenda for Europe as one of the seven pillars of the Europe 2020 Strategy. To this aim, GAMHer focuses on the need of a certified accuracy for surveying and monitoring projects with photogrammetry and laser scanning technologies, especially when used in a multiscale approach for landscape and built heritage documentation, conservation, and management. The approach used follows a multi-LoD (level of detail) transition that exploits GIS systems at the landscape scale, BIM technology and "point cloud based" 3d modelling for the scale of the building, and an innovative BIM/GIS integrated approach to foster innovation, promote users' collaboration and encourage communication between users. The outcomes of GAMHer are not intended to be used only by a community of Geomatics specialists, but also by a heterogeneous user community that exploit images and laser scans in their professional activities
MODELING THE DECAY IN AN HBIM STARTING FROM 3D POINT CLOUDS. A FOLLOWED APPROACH FOR CULTURAL HERITAGE KNOWLEDGE
No full textThe recent trends in architectural data management imply the scientific and professional collaborations of several disciplines involved in the design, restoration and maintenance. It seems an achieved concept that, in the next future, all the information connected to new interventions or conservation activities on historical buildings will be managed by using a BIM platform. Nowadays the actual range or image based metric survey techniques (mainly produced by using Terrestrial Laser Scanner or photogrammetric platform today more based on projective geometry) allow to generate 3D point clouds, 3D models, orthophotos and other outputs with assessed accuracy. The subsequent conversion of 3D information into parametric components, especially in an historical environment, is not easy and has a lot of open issues. According to the actual BIM commercial software and to the embedded tools or plugin, the paper deals with the methodology followed for the realization of two parametric 3D models (Palazzo Sarmatoris and Smistamento RoundHouse, two historical building in the north-west part of Italy). The paper describes the proposed workflow according to the employed plug-in for automatic reconstruction and to the solution adopted for the well-known problems connected to the modeling phase such as the vaults realization or the 3D irregular surfaces modeling. Finally, the studied strategy for mapping the decay in a BIM environment and the connected results with the conclusions and future perspectives are critically discussed
A Novel Cu-GNPs Nanocomposite with Improved Thermal and Mechanical Properties
No full textClassical powder metallurgy followed by either hot isostatic pressing (HIPing) or repressing-annealing process was used to produce Cu-graphene nanoplatelets (GNPs) nanocomposites in this work. A wet mixing method was used to disperse the graphene within the matrix. The results show that a uniform dispersion of GNPs at low graphene contents could be achieved, whereas agglomeration of graphene was revealed at higher graphene contents. Density evaluations showed that the relative density of pure copper and copper composites increased by using the post-processing techniques. However, it should be noticed that the efficiency of HIPing was remarkably higher than repressing-annealing process, and through the HIPing, fully dense samples were achieved. The Vickers hardness results showed that the reconsolidation steps can improve the mechanical strength of the specimens up to 50% owing to the progressive porosity elimination after reconsolidation. The thermal conductivity results of pure copper and composites at high temperatures showed that the post-processing techniques could enhance the conductivity of materials significantly
A Modular Cloud Robotics Architecture for Data Management and Mission Handling of Unmanned Robotic Services
No full textMany human service robotics applications are looking to cloud robotics as a possible paradigm in which robots, seen as remote and autonomous agents, have the possibility to connect to a common network and share information and knowledge they gather from real world on a complex and powerful data infrastructure. Conversely, they (the robots) can also consume data collected by other agents or made available on accessible database and repositories. In this paper, we propose a possible management of different services, exploiting the possibilities offered by cloud robotics in a complex scenario (smart city, smart agriculture, search & rescue). A high-level cloud platform manages several unmanned robots (UAVs and UGVs) with the goal of providing support to the end users that require it via a remote connection (web, SSH, VPN, etc.). The robots are used in the operating area while forwarding real-time data and video streaming to the final users, connected to the same cloud platform, that can manage them by remote
Surface science in hernioplasty: The role of plasma treatments
No full textThe aim of this review is to clarify the importance of surface modifications induced in biomaterials for hernia-repair application. Starting from the pioneering experiences involving proto-materials as ancient prosthesis, a historical excursus between the biomaterials used in hernioplasty was realized. Subsequently, after the revolutionary discovery of stereoregular polymerization followed by the PP application in the biomedical field performed by the surgeon F. Usher, a comparative study on different hernia-repair meshes available was realized in order to better understand all the outstanding problems and possible future developments. Furthermore, since many unsolved problems on prosthetic devices implantation are linked to phenomena occurring at the interface between the biomaterials surface and the body fluids, the importance of surface science in hernioplasty was highlighted and case studies of new surface-modified generations of prosthesis presented. The results discussed in the following evidence how the surface study are becoming increasingly important for a proper knowledge of issues related to the interaction between the living matter and the artificial prostheses