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Exhaust aftertreatment modeling for efficient calibration in diesel passenger car applications
No full textInterest in utilizing advanced lean-burn gasoline and diesel engines has increased in the last decades due to their reduced greenhouse gas emissions and increased fuel economy. One impediment to the increasing use of these engines, however, is the need to develop corresponding catalytic systems for controlling pollutant emissions. In particular, although still far from the fuel neutral United States (US) approach, European (EU) legislation limits for Nitrogen Oxides (NOx) emissions are becoming more and more severe and also type approval procedures are going to radically change with the introduction of Worldwide harmonized Light vehicles Test Cycle (WLTC) and Real Driving Emission (RDE) tests. Considering that test bench and chassis dyno experimental campaigns are costly and require a vast use of resources for the generation of data; therefore, reliable and computationally efficient simulation models are essential in order to identify the most promising technology mix to satisfy emission regulations and fully exploit advantages of diesel and lean-burn gasoline when minimizing the side effect of their emissions. Therefore, the aim of this work is to develop reliable models of the individual aftertreatment components and to calibrate the kinetic parameters based on experimental measurements which can be further used as a virtual test rig to evaluate the effectiveness of each technology in terms of reducing pollutant emissions. In the current work, a brief introduction regarding the passenger car emissions, regulations and control technologies, including in-cylinder control techniques and aftertreatment systems, is provided in Chapter 1. In addition, simulation modelling approaches for aftertreatment applications are discussed. More details about specific aftertreatment components are discussed in the next chapters. As an example, the modeling of a Selective Catalytic Reduction coated on Filter (SCR-F), on the basis of Synthetic Gas Bench (SGB) reactor data is presented in Chapter 2; focusing, in particular, on estimation of ammonia storage capacity, NOx conversion and soot reduction due to passive regeneration. LNT is analyzed in Chapter 3, focusing on the reactor-scale Synthetic Gas Bench (SGB) experiments and calibration of the 1D simulation model for two case studies with the aim to characterize Oxygen Storage Capacity (OSC), NOx Storage and Reduction (NSR) and light-off. The calibrated 1D simulation model is thereafter validated, in Chapter 4, for one of the case studies using engine-out emissions, mass flowrate and temperature traces over Worldwide harmonized Light vehicles Test Cycle (WLTC) as the boundary condition for the inlet of LNT for full-size component. Afterwards, the LNT model calibrated in Chapter 3 is, in Chapter 5, further reduced and linearized with reasonable assumptions to be used as a plant-model with very low computational requirement and in real time applications such as Electronic Control Unit (ECU)/ Hardware-in-the-Loop (HiL) systems. Finally, after discussing NOx control systems in previous chapters, modeling of Diesel Oxidation Catalyst (DOC), which plays a fundamental role not only for the CO and HC conversion, but also for promoting the oxidation of NO into NO2, is discussed in Chapter 6. It is worth noting that depending on the complexity of the kinetic model, different optimization tools are implemented for the calibration; as an example, Brent method is used for calibration of SCR-F kinetic model, likewise, Genetic Algorithm (GA) is used for the calibration of the DOC kinetic parameters; however, for more complex kinetic schemes like LNT both manual and automatic optimization is required to evaluate the most suitable reaction pathways and kinetic parameters. Accordingly, after development of the kinetic model for each aftertreatment component and validation of the full-scale model, further investigations could be devoted to combining the models in order to simulate the whole aftertreatment system and assess the performance over different driving cycles
The Effect of Temperature on Thermal Performance of Fumed Silica Based Vacuum Insulation Panels for Buildings
No full textVacuum Insulation Panels are characterized by very low thermal conductivity, which makes them alluring for building and civil sectors. However, considering the structure and composition of these materials, their application in buildings may be defined by a number of issues which need to be properly taken into account. The real performance of VIPs can be influenced by the boundary conditions (e.g. temperature) at which they work during their operation. In this paper experimental analyses aimed at characterising the relationship between the centre of panel thermal conductivity and average temperature were carried out. The experiments were performed on two VIP samples with different thickness. Moreover a comparison with non-evacuated panels and a traditional insulating material was performed
Inter-controller Traffic to Support Consistency in ONOS Clusters
No full textIn distributed SDN architectures, the network is controlled by a cluster of multiple controllers. This distributed approach permits to meet the scalability and reliability requirements of large operational networks. Despite that, a logical centralized view of the network state should be guaranteed, enabling the simple development of network applications. Achieving a consistent network state requires a consensus protocol, which generates control traffic among the controllers whose timely delivery is crucial for network performance. We focus on the state-of-art ONOS controller, designed to scale to large networks, based on a cluster of self-coordinating controllers. In particular, we study the inter-controller control traffic due to the adopted consistency protocols. Based on real traffic measurements and the analysis of the adopted consistency protocols, we develop some empirical models to quantify the traffic exchanged among the controllers, depending on the considered shared data structures, the current network state (e.g. topology) and the occurring network events (e.g. flow or host addition). Our models provide a formal tool to be integrated into the design and dimension the control network interconnecting the controllers. Our results are of paramount importance for the proper design of large SDN networks, in which the control plane is implemented in-band and cannot exploit dedicated network resources
Energy: a study for advanced solutions including low-neutron nuclear fusion
No full textThis paper illustrates an interdisciplinary approach to help solve the energy problem in the Twenty-First Century, and how innovative nuclear energy sources can be a solution. The situation of the world energy issue is demonstrating how an interdisciplinary approach is probably necessary to sketch out a solution. Most of the studies and experiments on nuclear fusion are currently devoted to the Deuterium-Tritium (DT) fuel cycle, however proposed experimental tokamaks based on "advanced' reactions, such as Deuterium-Helium-3 (DHe3), show a much more marked difference with fission reactors. The "zero-waste" option is a clear advantage of DHe3 fusion power versus fission, in view of its ultimate safety and public acceptance. Fusion reactors with advanced DHe3 fuel cycle turn out to have quite outstanding environmental advantages
Characterization of sludge resulting from the extraction and processing of natural stones. focus on a Piedmont case
No full textThe problem of the management of sludge resulting from the extraction and processing of ornamental stones is currently one of the key issues for the European Union and for Italy. The European Community, through Directive 2006/21/EC (Management of waste from extractive industries - Mining waste), Directive 2008/98/EC (Waste Framework) and Directive 1999/31/EC (Landfill Waste), has provided guidelines for its member countries on how to handle wastes, in view of a future sustainable development of the sector, especially as far as critical raw material (CRM) is concerned. In this context, an analysis of the procedure applied to extract and cut two similar Piedmont silicatic stones into slabs and to manage their sludge has been carried out. The ornamental stones taken into consideration are Diorite of Traversella and Perosa Stone (Dioritic gneiss). The following procedures were conducted to characterise the stones: petrographic analysis, as well as compressive strength, flexural strength, impact resistance and water absorption tests. This characterization is important to help choose the best available technique to extract and process the stones. The methodologies adopted in two different plants, according to their processed stones, are discussed hereafter. In addition, UPV and Knoop analyses were performed in order to establish the workability class of the two stones, and the classification developed in previous research works was applied. Subsequently, an analysis was conducted on the sludge resulting from the extraction and processing of blocks used for the production of slabs. A chemical analysis, a particle size analysis, a magnetic separation test, to obtain two fractions (metallic and mineral), and an SEM analysis of the two separated fractions were performed on the two sludges. This characterization was useful to understand whether the produced sludge could be recovered as by-products. The study will help stone producers to identify the best techniques for the extraction and processing of their stones, while obtaining less waste and less pollution
EPAnHaus project: assessment of the energy use for climate control into animal houses
No full textEnvironmental conditions of livestock housing can affect the quality and the costs of the animal production. Many environmental parameters (e.g. indoor air temperature, indoor relative humidity) must be set up and controlled to maintain animal welfare, to prevent the incidence of certain diseases, and to raise productive performance of the animals. This control is generally carried out by mechanical system that entails an energy consumption for heating, cooling and ventilation, that for some livestock housing (e.g. pig and broiler buildings) may be an important part of the total running costs of the structure. Those energy consumptions and costs may be reduced by improving the thermos-physical features of the building envelope or increasing the efficiency of the used mechanical systems. To understand the effectiveness of each action regarding the envelope and/or the mechanical system, it is necessary to assess the performance of the different livestock houses. While several investigations have been carried out for the assessment, certification and improvement of the energy performance of human-related buildings (e.g. residential and retail), in the livestock sector there was not a similar attention. For this reason, the EPAnHaus (Energy Performance of Livestock Houses) project aims at defining an energy certification scheme that considers all the energy uses related to the control of indoor environment: heating, ventilation (both for cooling and Indoor Air Quality) and cooling. This project was developed through three different steps. First, an inventory of the energy use for climate control of the animal houses across Europe was made for determining benchmark values. Then, a calculation method derived from ISO Standards on building energy performance was customized for being applied to the animal production buildings to assess the energy use for climate control. It was applied into different calculation tools (some developed in cooperation with industry). Their outputs were used for defining the energy certification scheme. Finally, measurement campaigns were carried out in some livestock houses for testing and refining the models referring to the different housing types. The use of the certificate will make available the possibility to know the actual amount of energy consumed for the climate control and information about retrofitting actions (e.g. simple payback period and energy savings). Acknowledgements This work was done through the financial support of the SIR 2014 "EPAnHaus - Energy performance certification of livestock houses" project, grant number RBSI141A3A, funded by Italian Ministry of Education, University and Research (MIUR)
Unsupervised methodology to unveil content delivery network structures
No full textA method for analyzing a content delivery network. The method includes obtaining network traffic flows corresponding to user nodes accessing contents from a set of servers of the content delivery network, extracting a timing attribute from each network traffic flow associated with a server, where the timing attribute is aggregated into a timing attribute dataset of the server based on all network traffic flows associated with the server, generating a statistical measure of the timing attribute dataset as a portion of a feature vector representing the server, where the feature vector is aggregated into a set of feature vectors representing the set of servers, analyzing the set of feature vectors based on a clustering algorithm to generate a set of clusters, and generating, based on the set of clusters, a representation of server groups in the content delivery network
Multitemporal 3D modelling for cultural heritage emergency during seismic events: Damage assesment of S. Agostino church in Amatrice (RI)
No full textFare urbanistica tra XI e XIV secolo, a cura di Claudia Bonardi, "Storia dell'Urbanistica", 7/2015, Roma, Kappa, 2016, pp. 423, ill
No full textRecensione al numero monografico della rivista "Storia dell'Urbanistica", dedicato alle forme insediative medievali e alla relativa urbanistica tra XI e XIV secol
Developing parameters for multi-mode ambient air models including the nanometer mode
No full textThe particle count, surface and mass in an occupied space can be modeled when the HVAC system airflows are known, along with the particle-size distribution for outdoor air, internal generation rates as a function of particle size, and the efficiency as a function of particle size for filters present. Outdoor air particle-size distribution is rarely available, but measures of particle mass concentration, PM2.5 and PM10, are often available for building locations. Outdoor air aerosol size distributions are well modeled by sums of two or three log-normal distributions, with essentially all mass in two larger modes. Studies have also shown that some mode parameters are, in general, related by simple functions. This paper shows how these relationships can be combined with known characteristics of PM2.5 and PM10 samplers to create reasonable inclusive models of outdoor air aerosol-size distributions. This information plus knowledge of indoor particle generation allows calculation of aerosol mass in occupied spaces. Estimation of parameters of aerosol modes with sizes below 100 nm and measurement of filter efficiencies in that range are described