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The real assets, procedures, systems,and subsystems of a city can be virtually represented throughan urban digital twin(DT),which integrates heterogeneous data to learn and evolve with the physical city,offering support to monitor the current status and predict possible future scenarios.A DT of a city can be organized into layers, which represent specific facets of the city and cooperate to address specifici ssues.In this work,we present an application scenario in which a geometric layer,representing the 3D morphology of the urbane nvironment, cooperates with an energy consumption layer,providing knowledge of the peculiarities of thebuilding urban area and in particular of the built fabric,to assess their impact in terms of energy efficiency.The analysis of the urban geometries provides quantitative measuresas useful input,for instance,to define heat leakage.

The aim of the paper is to study the influence of the power transformer on signal transmission in the case of a power line communication (PLC) system in a overhead Medium Voltage (MV) power network. A model of the PLC system was carried out by means of the Simulink® software. A distributed parameter MV overhead line, two power transformers, the signal coupling interface of a ST7540 FSK powerline transceiver were included in the model. The performances of the complete PLC communication system are evaluated for different line lengths by means of the attenuation computed as ratio between the received and transmitted voltage signals. © 2011 IEEE.

Technologies for direct injection of fuel in compression ignition engines are in continuous development. One of the most investigated components of this system is the injector; in particular, main attention is given to the nozzle characteristics as hole diameter, number, internal shape, and opening angle. The reduction of nozzle hole diameter seems the simplest way to increase the average fuel velocity and to promote the atomization process. On the other hand, the number of holes must increase to keep the desired mass flow rate. On this basis, a new logic has been applied for the development of the next generation of injectors. The tendency to increase the nozzle number and to reduce the diameter has led to the replacement of the nozzle with a circular plate that moves vertically. The plate motion allows to obtain an annulus area for the delivery of the fuel on 360 degrees; while the plate lift permits to vary the atomization level of the spray. The experimental activities have been performed on a single-cylinder metal engine in order to evaluate the new injector concept functionality in typical engine working conditions. Then a deeper investigation of injector the characteristics has been performed in an optical single-cylinder diesel engine via high speed digital imaging in order to catch information on its operation. The results have shown a good response of the injector fuel delivery control but penalties in terms of emissions and efficiency compared to multihole nozzles. Images of the injection process showed that the fuel assumed an asymmetric shape at the exit of the injector affecting the mixing quality and, then, the combustion efficiency.

As of mid-2017, there were ~7500 metric tons of mass in orbit around the Earth, of which about 95% concentrated in almost 6700 intact spacecraft and orbital stages. Among them, nearly 80% were abandoned and more than 90% could not be maneuvered. The intact objects abandoned in LEO above ~650 km, i.e. with a typical residual lifetime of more than 25 years, represent the main potential mass reservoir for the generation of new detrimental orbital debris in case of mutual collisions with the existing debris environment. A practicable strategy to assess the latent long-term environmental impact of an orbiting object is to devise a ranking scheme based on simplified and reasonable inferences. Several ranking schemes have been proposed by different authors during the last decade. Various "criticality indexes" have been devised by us (at ISTI-CNR) in the last few years, and they have been applied to evaluate the environmental impact of many families of rocket bodies and selected spacecraft. A couple of the most complete indexes formulated by us are herein applied to assess the potential criticality of the most massive objects abandoned in LEO.

AbstractThe surface oxygen exchange on oxides with high oxygen ion mobility is modelled with a two step reaction with adsorbed mono-atomic oxygen species as intermediate. Interpretation of the Po2 dependence of the exchange rates, following from this model, indicates that these adsorbed oxygen atoms are singly charged.For the stabilized δ-Bi2O3 solid electrolyte a good agreement has been found between the isotope exchange model and the electrochemical study of the oxygen exchange using gold electrodes. For the mixed La-Sr cobaltite perovskite a change in the surface exchange reaction is observed going from room temperature to 600°C. Indications are that above 450°C the bulk exchange is rate limiting with a (Po2)−1 dependence while below this temperature it is assumed that the dissociative adsorption is rate limiting with a (Po2)1/2 dependence.

A good process understanding is the foundation for process optimization, process monitoring, end-point detection, and estimation of the end-product quality. Performing good process measurements and the construction of process models will contribute to a better process understanding. To improve the process knowledge it is common to build process models. These models are often based on first principles such as kinetic rates or mass balances. These types of models are also known as hard or white models. White models are characterized by being generally applicable but often having only a reasonable fit to real process data. Other commonly used types of models are empirical or black-box models such as regression and neural nets. Black-box models are characterized by having a good data fit but they lack a chemically meaningful model interpretation. Alternative models are grey models, which are combinations of white models and black models. The aim of a grey model is to combine the advantages of both black-box models and white models. In a qualitative case study of monitoring industrial batches using near-infrared (NIR) spectroscopy, it is shown that grey models are a good tool for detecting batch-to-batch variations and an excellent tool for process diagnosis compared to common spectroscopic monitoring tools.