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Behavioral, Parameterized, and Broadband Modeling of Wired Interconnects with Internal Discontinuities
No full textWe present a complete workflow for the extraction of behavioral reduced-order models of wired interconnect links, including an explicit dependence on geometrical or material parameters describing internal discontinuities that may affect the quality of signal transmission. Thanks to the adopted structure, the models are easily identified from sampled frequency responses at discrete points in the parameter space. Such responses are obtained from off-the-shelf full-wave solvers. A novel algorithm is used for checking and enforcing model stability and passivity, two fundamental requirements for reliably running stable transient simulations. Finally, an ad hoc procedure is devised to synthesize the models as parameterized circuit equivalents, compatible with any SPICE solver. Several examples illustrate and validate the workflow, confirming the suitability of the proposed approach for what-if, parameter sweep, design centering, and optimization through time-domain simulations, possibly including nonlinear devices and terminations
Optimized design and characterization of motor-pump unit for energy-regenerative shock absorbers
No full textThe constant need to reduce emissions in the automotive sector has driven the electrification of powertrain and chassis. To comply with this trend and decrease the bound even further, the present paper proposes the use of hydraulic regenerative shock absorbers for automotive suspension systems. The conversion of linear into angular motion and the suitable control of an integrated electric machine allow to transform part of the vibrational energy into electricity. In these damping devices, the key element is the motor-pump unit that is interfaced onto a conventional hydraulic cylinder architecture. Hence, the proposed research focuses on this component by investigating different design aspects in all the domains of interest. The objective is to optimize the energy conversion efficiency of the unit without affecting its damping control property. To give means of validation, a motor-pump prototype is built and experimentally characterized through a dedicated test rig
Morphology and dispersion of nanostructured manganese-cobalt spinel on various carbon supports: the effect on the oxygen reduction reaction in alkaline media
No full textIn this work a model nanometric manganese-cobalt spinel was deposited on five selected carbon carriers (Vulcan XC-72, Printex85, MWCNT, mesoporous carbon CMK-1, and amorphous carbon C-am.) to examine their role in modifying the electrocatalytic properties of the supported active phase for the oxygen reduction reaction (ORR) in alkaline media. The synthesized materials were thoroughly characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), and Raman spectroscopy (RS). The results confirmed formation of a highly crystalline nanometric manganese-cobalt spinel and allowed for assessment of the amorphous phase content in the used carbon supports. The composition of the obtained catalysts was investigated by thermo-gravimetric analysis (TGA) and X-ray fluorescence (XRF) measurements. The electrocatalytic properties of the supported spinels were determined by the rotating disk electrode (RDE) and the rotating ring-disk electrode (RRDE) methods, and compared with a commercial platinum catalyst (20 wt.% Pt/Vulcan XC-72). TEM analysis revealed that the carbon support governs both the dispersion and morphology of the deposited spinel. In the case of mesoporous and amorphous carbon supports, the spinel nanocrystals exhibit the polyhedral shapes with almost equal abundance of the (111) and (100) facets. The shape of the spinel nanocrystals deposited on the Vulcan XC-72 and Printex85 supports is dominated by the (111) termination, whereas for the MWCNT support the (100) facet is the most abundant accompanied by the highest dispersion of the nanoparticles. The ORR measurements revealed that the amorphous phase fraction in the carbon support promotes 2e- reduction, leading to production of HO . This undesired pathway is inhibited by preferential exposition of the (100) facets. The superior performance of the MWCNT support in the 4e- reduction process results from three factors: lowest content of the amorphous component, best dispersion of the spinel active phase, and its ability to promote preferential (100) faceting of the nanocrystals
Optimisation analysis of PCM-enhanced opaque building envelope components for the energy retrofitting of office buildings in Mediterranean climates
No full textThe energy retrofitting of existing buildings is of major importance to reach the energy sustainability target set by the European Union (EU) for 2020. Innovative retrofitting solutions can involve the adoption of Phase Change Materials (PCMs), but an effective use of PCM in buildings requires an appropriate selection of the thermo-physical properties, quantity and position of the PCMs. To guarantee a good functioning of a PCM and ensure economic feasibility, an optimisation of PCM use is advisable. In the present paper, multi-objective optimisation analyses for the energy retrofitting of office buildings with PCM-enhanced opaque building envelope components are presented. A retrofitting intervention on either the external or internal side of the opaque envelope was considered, and a maximum of two PCM layers with different melting temperatures were selected and placed in different positions within the wall. Two sets of objective functions were minimised; first, primary energy consumption and global costs, and then the building energy needs for heating and cooling and investment costs. The search variables included the thickness and thermo-physical properties of the PCM layers, the window type, the insulation and internal lining materials, the wall configuration and U-value. In order to provide a robust methodology to drive designers towards an informed choice of the final retrofitting strategy, post-optimisation analyses were additionally carried out to investigate the variable values that led to the optimal solutions. Interesting and non-trivial information was obtained. The optimal thermo-physical properties of PCMs were found to be affected in particular by the operation of the HVAC system
Raffaello tifava Roma (antiqua)
No full textAnticipazione sul Domenicale del Sole24Ore di domenica 7 gennaio 2018 di uno stralcio della voce bibliografica "Raffaello Santi o Sanzio" pubblicato nel volume n. 90 del «Dizionario Biografico degli Italiani», Roma, 201
Harmonic pulse testing for well performance monitoring
No full textHarmonic testing was developed as a form of well testing that can be applied during ongoing production or injection operations, as a pulsed signal is superimposed on the background pressure trend. Thus no interruption of well and reservoir production is needed before and during the test. If the pulsed pressure and rate signal analysis is performed in the frequency domain, strong similarity exists between the derivative of the harmonic response function versus the harmonic period and the pressure derivative versus time, typical of conventional well testing. Thus the interpretation of harmonic well tests becomes very straightforward. In this paper, we present the analytical models for the most commonly encountered well and reservoir scenarios and we validate the model for horizontal wells against real data of a harmonic test performed on a gas storage well in Italy
System and AOCS Challenges for the Design Consolidation of the Next Generation Gravity Mission
Full text linkA 3D layer-wise model for the correct imposition of transverse shear/normal load conditions in FGM shells
No full textWelfare words. Critical social work & social policy, by Paul Michael Garrett, Los Angeles, London, New Delhi, Singapore, Washington DC and Melbourne, Sage, 2017, 288 pp., £24.99 (paperback), ISBN: 9781473968974
No full textUAV photogrammetry for archaeological site survey. 3D models at the Hierapolis in Phrygia (Turkey)
Full text linkUnmanned aerial vehicle (UAV) photogrammetry has shown a very rapid development in many fields, especially in archaeological excavation areas and architectural complexes, where it offers a detailed generation of three-dimensional (3D) data including the possibility of updating over time. It also proves to be a very flexible tool applicable to many types of complex areas with a variety of different features. The use of aerial acquisition provides highly effective results, adding to both rapid capture and lower costs. In fact, today in the field of archaeological research, great efforts are invested in the generation of very large-scale models and orthophotos, and the technology seems to promise further future developments, not only from the terrestrial (orthogonal) point of view, but also from the nadiral direction from a low altitude, as a preferential and often optimal point of view. Here an effective workflow for photogrammetric product generation is presented for selected case studies in some monumental areas of ancient Hierapolis in Phrygia (Turkey), in which the Italian Archaeological Mission of Hierapolis (MAIER) has been working since the 1960s. The recent experiences achieved by UAV photogrammetry are quite innovative. The variety and complexity of the buildings, as well as the height of their ruins, offer numerous challenges, which are interesting to deal with. The 3D aerial survey was performed for multiple purposes with the eBee system by Sensefly. Specific attention was paid to the digital surface model (DSM) and aerial orthoimages of three test areas: the Plutonium area; the Thermal Bath-Church; and the Necropolis. Starting from the same technical approach, a comparative assesment among the three sites was carried out, taking into account the specific goals, the type of the structure and the terrain conformation