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Confronto tra differenti reagenti per la degradazione di solventi clorurati e l'immobilizzazione di mercurio
No full textNel presente lavoro si illustra una sperimentazione di laboratorio eseguita per valutare la fattibilità di una riduzione chimica in situ (ISCR) per la bonifica di acque sotterranee contaminate da solventi clorurati e mercurio. La sperimentazione è stata condotta in batch, su microcosmi contenenti acqua e terreno di sito, mantenuti in condizioni anaerobiche e a temperatura di falda. Sono stati testati tre diversi reagenti, ciascuno a quattro dosaggi differenti: ferro zerovalente, solfuro ferroso (pirite) ed un prodotto commerciale a formulazione brevettata. Sulla base dei risultati ottenuti, il reagente commerciale con il dosaggio all'1%wt è stato ritenuto quello con migliore rimozione dei contaminanti obiettivo, senza mobilizzazione dei contaminanti indesiderati. La sua sperimentazione in scala pilota sarà oggetto della seconda parte dello studio
Formaldehyde production plant modification: Risk based decision making
No full textIn case of plant modification, one of the guiding parameters for decision making should be the risk minimisation. Traditional and recognised risk assessment methodologies (i.e. HazOp, Fault Tree, Event Tree) are static and strongly affected by the experience of the analysis team. But in case of plant modification, the team knowledge can be not sufficient. Thus, it became particularly important to have a system able to model, in an integrated way, both the probability of occurrence of possible unwanted events, and the behaviour of the process when an unwanted event occurs; this will allow the decision to be taken on a complete set of information and definitely on risk. The dynamic decision analyses are based on the results of a joint logical-probabilistic model and phenomenological model. In this paper, in particular, the Integrated Dynamic Decision Analysis is applied to a formaldehyde production plant, where a decision has to be taken about modifying the whole cooling system of the process from a melted salts based system, with a higher environmental impact potential, to a water based system
Design of product and process for Metal Additive Manufacturing - From design to manufacturing
No full textAdditive Manufacturing (AM) is a recent new manufacturing approach that is based on the fabrication of each object using a layer-by-layer strategy. From a manufacturability perspective of components, this approach involves the possibility to manufacture parts of any geometric complexity without using additional tools and machines. Particular attention is dedicated to the powder bed fusion (PBF) AM processes in which a laser beam or an electron beam is used to sinter or melt metallic powders which are named Selective Laser Melting (SLM) and Electron Beam Melting (EBM). In fact, in these last years, growing interesting of the industry has been outlined for metal AM, because they offer exclusive benefits such as the direct production of complex functional and/or end-usable parts made with excellent materials. Today it is thus recognised the need for guidelines and tools for effective introduction of the AM processes in the metal industry. To address this issue the aim of the presented thesis was to propose concurrent engineering (CE) tools based on a comprehensive approach from design to manufacturing. The metal PBF-AM processes have been dealt by two subsequent steps. The first one addressed the development of a process selection (PS) tool that combines materials, processes and designs for the choice of the best alternative to produce a metal component. The second one concerned with the development of a model for the process simulation that can contribute to the understanding of the process. The proposed PS tool aimed to introduce the metal AM processes as alternative to producing components. In particular, the tool was implemented in order to consider the comparison between different metal AM manufacturing processes as well as AM, machining and casting. In this approach, each alternative is represented by a combination of the design, material and process features. A well-structured open architecture for PS has been suggested. The tool works by considering the requirements of the component regarding geometry constraints and specifications. A methodology based on mathematical modeling design decisions involving multiple attributes was suggested to assess the technical and economic aspects in order to analyse and rank the alternatives. For this purpose, an index, called DePri, was introduced to resume technical aspects and offers a quantitative comparison between the alternatives. On the other, the economic aspect for AM has been addressed by providing a detail model cost. The results of the process selection in which the technical aspect of each alternative has been considered and the alternatives can be compared with the corresponding manufacturing cost. An application of the proposed tool was demonstrated by an industrial case study in which the objective was to assess the best technology resource between 3-axis CNC machining, SLM and EBM for future investments of the company in the AM technologies. The second issue addresses the optimisation of the metal PBF-AM process by virtual simulation for a suitable selection of the process parameters. In this context, the resulting review showed the SLM as a consolidated process respect to process simulation while EBM has received less attention despite the numerous applications in the medical and aerospace fields. In order to improve the effectiveness and reliability of EBM FE simulation, a new type of modelling has been introduced for the energy source and the powder material properties which have been included in a thermal numerical model. The potential of the proposed modelling was demonstrated using comparison with existing experimental literature data for a single straight line, existing model in published literature and experimental measurements for multibeam and continuous line melting. The model was then used to investigate the effects of the process parameters on the microstructures of a TiAl alloy
Ultrastrong and flame-resistant freestanding films from nanocelluloses, self-assembled using a layer-by-layer approach
No full textInvestigation of droplet breakup in liquid-liquid dispersions by CFD-PBM simulations: The influence of the surfactant type
No full textThe accurate prediction of the droplet size distribution (DSD) in liquid-liquid turbulent dispersions is of fundamental importance in many industrial applications and it requires suitable kernels in the population balance model. When a surfactant is included in liquid-liquid dispersions, the droplet breakup behavior will change as an effect of the reduction of the interfacial tension. Moreover, also the dynamic interfacial tension may be different with respect to the static, due to the fact that the surfactant may be easily desorbed from the droplet surface, generating additional disruptive stresses. In this work, the performance of five breakup kernels from the literature is assessed, to investigate their ability to predict the time evolution of the DSD and of the mean Sauter diameter, when different surfactants are employed. Simulations are performed with the Quadrature Method of Moments for the solution of the population balance model coupled with the two-fluid model implemented in the compressibleTwoPhaseEulerFoam solver of the open-source computational fluid dynamics (CFD) code OpenFOAM v. 2.2.x. The time evolution of the mean Sauter diameter predicted by these kernels is validated against experimental data for six test cases referring to a stirred tank with different types of surfactants (Tween 20 and PVA 88%) at different concentrations operating under different stirrer rates. Our results show that for the dispersion containing Tween 20 additional stress is generated, the multifractal breakup kernel properly predicts the DSD evolution, whereas two other kernels predict too fast breakup of droplets covered by adsorbed PVA. Kernels derived originally for bubbles completely fail
Digital Shaping and Optimization of Fuel Injection Pattern for a Common Rail Automotive Diesel Engine through Numerical Simulation
No full textDevelopment trends in modern Common Rail Fuel Injection System (FIS) show dramatically increasing capabilities in terms of optimization of the fuel injection pattern through a constantly increasing number of injection events per engine cycle along with a modulation and shaping of the injection rate. In order to fully exploit the potential of the abovementioned fuel injection pattern optimization, numerical simulation can play a fundamental role by allowing the creation of a kind of a virtual injection rate generator for the assessment of the corresponding engine outputs in terms of combustion characteristics such as burn rate, emission formation and combustion noise (CN). This paper is focused on the analysis of the effects of digitalization of pilot events in the injection pattern on Brake Specific Fuel Consumption (BSFC), CN and emissions for a EURO 6 passenger car 4-cylinder diesel engine. The numerical evaluation was performed considering steady-state conditions for 3 key points representative of typical operating conditions in the low-medium load range. The optimization process was carried out through numerical simulation, by means of a suitable target function aiming to minimize BSFC and CN while not exceeding the target NOx emissions level. By means of a previously developed fuel injection system model, possible different injection patterns with high number of pilot injections were evaluated thus obtaining a kind of virtual injection rate generator, the outcomes of which were then used as input for a DIPulse combustion model in order to predict BSFC, combustion noise and emissions. Through numerical optimization of pilot injection pattern digitalization, potential for achieving significant reductions in BSFC and CN for low load engine points while not exceeding the target NOx emissions level, was demonstrated
Il recupero delle cattedrali dell'energia
No full textElectricity has been the base for new technologies that have had, and still have, a significant impact on architecture, building design and people life. It is an industrial heritage, but above all a cultural heritage strong related to the territory and the population. Thanks to science and technology advances which took place in the last decades of the nineteenth century, lots of electrical power stations voted to the production of electricity, mainly used in the lighting of public spaces and buildings or in urban transport, are erected next to the urban centres. Many of these power plants, whose equipment generally used fossil fuels (mainly coal and diesel) for electricity production, have been progressively abandoned since the end of the seventies of the last century. Some of them have been totally demolished, others have conversely undergone interventions in which conservation and transformation requests have not always been adequately combined. This paper intends to focus on the critical analysis of some recent adaptive reuse interventions carried out on fallen into disuse power plants in the last decades of the twentieth century, highlighting the differences that characterize the outcomes of such interventions
A microwave system connected to a IoT infrastructure for weed seed bank depletion
No full textThe paper presents a general preliminary overview of a system connected to a communication infrastructure in order to improve the agriculture. The core of the system is the weed seed bank depletion by means of microwave based heating solution. The microwave technique is supported by a vision system, which can be used both in visible and infrared band according to different crops in order to maximize its efficiency, and a GPS based localization system. All the parameters to program and control the proper working of the systems, as well as measured data, are available with a specific application, making the whole system perfectly integrated in the world of Internet of Thing (IoT). Some technology solutions are addressed and some possible choices to realize each section are reported. The description of the whole system is reported as well
Legal aspects of information science, data science, and Big Data
No full textThis chapter investigates the limits and criticisms of the existing legal framework and the possible options to provide adequate answers to the new challenges of Big Data processing. In this light, this chapter is divided into three main sections. The first section focuses on the traditional paradigm of data protection and on the provisions, primarily in the new EU General Data Protection Regulation (Regulation (EU) 2016/679, hereafter GDPR), that can be used to safeguard individual rights in Big Data processing. The second section goes beyond the existing legal framework and, in the light of the path opened by the guidelines on Big Data adopted by the Council of Europe, suggests a broader approach that encompasses the collective dimension of data protection. This dimension often characterizes Big Data applications and leads to assess the ethical and social impacts of data uses, which assume an important role in many Big Data contexts. The last section deals with the use of Big Data to anticipate fraud detection and to prevent crime. In this light, the new Directive (EU) 2016/680 † is briefly analyzed. D