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J/ψ suppression at forward rapidity in Pb-Pb collisions at sNN=5.02 TeV
No full textThe inclusive J/ψ production has been studied in Pb-Pb and pp collisions at the centre-of-mass energy per nucleon pair View the MathML source, using the ALICE detector at the CERN LHC. The J/ψ meson is reconstructed, in the centre-of-mass rapidity interval 2.5<y<4 and in the transverse-momentum range pT<12 GeV/c, via its decay to a muon pair. In this Letter, we present results on the inclusive J/ψ cross section in pp collisions at View the MathML source and on the nuclear modification factor RAA. The latter is presented as a function of the centrality of the collision and, for central collisions, as a function of the transverse momentum pT of the J/ψ . The measured RAA values indicate a suppression of the J/ψ in nuclear collisions and are then compared to our previous results obtained in Pb-Pb collisions at View the MathML source. The ratio of the RAA values at the two energies is also computed and compared to calculations of statistical and dynamical models. The numerical value of the ratio for central events (0-10% centrality) is 1.17±0.04(stat)±0.20(syst). In central events, as a function of pT, a slight increase of RAA with collision energy is visible in the region 2<pT<6 GeV/c. Theoretical calculations qualitatively describe the measurements, within uncertainties
CHALLENGES AND OPPORTUNITIES FOR THE IMPLEMENTATION OF H-BIM WITH REGARDS TO HISTORICAL INFRASTRUCTURES: A CASE STUDY OF THE PONTE GIORGINI IN CASTIGLIONE DELLA PESCAIA (GROSSETO - ITALY)
No full textHistorical Building Information Modeling (H-BIM) has been widely documented in literature and is becoming more popular with government bodies, who are increasingly choosing to make its use mandatory in public procurements and contracts. Although the system seems to be one of the best approaches for managing data and driving the decision-making process, several difficulties arise due to the amount of effort required in the initial phases, when the data derived from a geometrical survey must be converted into parametric elements. Moreover, users must decide on a "level of geometrical simplification" a long time in advance, and this inevitably leads to a loss of geometrical data. From this perspective, our research describes a procedure to optimize the workflow of information for existing artefacts, in order to achieve a "lean" H-BIM. In this article, we will analyse two aspects: the first relates to the level of accuracy in a digital model created from the two different point clouds achieved from laser scanner and form images, while the second concerns the conversion of this information into parametric elements (Building Object Models- BOMs) that need to have specific characteristics. The case study we are presenting is the "Ponte Giorgini" ("Giorgini Bridge") in Castiglione della Pescaia (Grosseto - Italy)
Flow Dominance and Factorization of Transverse Momentum Correlations in Pb-Pb Collisions at the LHC
No full textWe present the first measurement of the two-particle transverse momentum differential correlation function, P-2 = <Delta pT Delta p(T)>/ < p(T)>(2), in Pb-Pb collisions at root s(NN) = 2.76 TeV. Results for P-2 are reported as a function of the relative pseudorapidity (Delta eta) and azimuthal angle (Delta phi) between two particles for different collision centralities. The Delta phi dependence is found to be largely independent of Delta eta for broken vertical bar Delta eta broken vertical bar >= 0.9. In the 5% most central Pb-Pb collisions, the two-particle transverse momentum correlation function exhibits a clear double-hump structure around Delta phi=pi (i. e., on the away side), which is not observed in number correlations in the same centrality range, and thus provides an indication of the dominance of triangular flow in this collision centrality. Fourier decompositions of P-2, studied as a function of the collision centrality, show that correlations at broken vertical bar Delta eta broken vertical bar >= 0.9 can be well reproduced by a flow ansatz based on the notion that measured transverse momentum correlations are strictly determined by the collective motion of the system
A robust capacitive digital read-out circuit for a scalable tactile skin
No full textThis paper presents a robust, capacitive digital readout circuit (ROC) for sensitive skin applications in humanoid robots. The ROC can be calibrated to null the parasitic effects of transducer variation due to physical assembly. A prototype is fabricated in a 130 nm RFCMOS process, with an active area of 221 × 79 μm2 and 1.84 μW power consumption at VDD = 1.2V and 1ms read-out rate. The ROC output is robust to VDD and temperature variations in a range |ΔVDD| ≤ 20% and (25-53)°C. Furthermore, it can provide up to 200mVpp power supply sine wave rejection in the range 50Hz-5MHz at VDD = 1.1V, for an output standard deviation lower than one LSB. Owing to its features and its digital modularity, the ROC was co-designed with a scalable and modular Multi-Walled Carbon NanoTube (MW-CNT) Nano composite transducer, to achieve tunable output sensitivity by adjusting the sensor nominal capacitance and the reference capacitance. The maximum sensitivity of 5.23 fF per LSB was reached when both match. The ROC was then validated with the MW-CNT nanocomposite sensor which exhibits a piecewise behaviour. 5.3 and 7.1 ENOB were extrapolated in the low-load and medium-load regions, respectively. Besides the major advantage of tunable sensitivity, the presented ROC features the lowest acquisition time and one of the most compact sizes among the state-of-the-art ROCs. Moreover, process voltage and temperature (PVT) robust output and ultralow power consumption make this solution very attractive to replicate human physiology at robotic-level
THE GEOMATICS CONTRIBUTION FOR THE VALORISATION PROJECT IN THE ROCCA OF SAN SILVESTRO LANDSCAPE SITE
No full textThis paper proposes an emblematic project where several multi-sensor strategies for spatial data acquisition and management, range based and image based, were combined to create a series of integrated territorial and architectural scale products characterized by a rich multi-content nature. The work presented here was finalized in a test site that is composed by an ensemble of diversified cultural deposits; the objects that were surveyed and modelled range from the landscape with its widespread mining sites, the main tower with its defensive role, the urban configuration of the settlement, the building systems and techniques, a medieval mine. For this reason, the Rocca of San Silvestro represented a perfect test case, due to its complex and multi-stratified character. This archaeological site is a medieval fortified village near the municipality of Campiglia Marittima (LI), Italy. The Rocca is part of an Archaeological Mines Park and is included in the Parchi della Val di Cornia (a system of archaeological parks, natural parks and museums in the south-west of Tuscany). The fundamental role of a deep knowledge about a cultural artefact before the planning of a restoration and valorisation project is globally recognized; the qualitative and quantitative knowledge provided by geomatics techniques is part of this process. The paper will present the different techniques that were used, the products that were obtained and will focus on some mapping and WEB GIS applications and analyses that were performed and considerations that were made
Deploying traditional and smartphone app survey methods in measuring door-to-door travel satisfaction in eight European cities
No full textThis study describes the lessons learned from designing, deploying and analysing the results from different travel satisfaction survey tools which measures the travellers' door-to-door travel satisfaction. The travel satisfaction measurement survey tools tested consisted of two types of smartphone applications (a satellite navigation app and a game app), an on-line survey, a paper-based semi-structured questionnaire and a focus group questionnaire. Each of the measurement tools comprised the same set of basic questions, but in different formats, aimed at exploring the pros and cons of each tool among different groups of travellers. The data collection was carried out at eight different European cities and five FIA motorist networks. 5,275 valid responses were gathered from the survey. Further analysis results show that different survey methods performed better in different sites. The satisfaction that was gathered via main trip leg does not necessarily correspond with overall satisfaction of the door-to-door journey. The results of this study highlight the need for more inclusive, complete, door-to-door, travel survey measurements
Catalytic combustion of methane in lean conditions on Pd/Co3O4 : from powdered to open-cell foam supported catalysts
No full textThe aim of this work is an investigation on a series of Pd-doped cobalt spinels catalysts for the lean CH4 combustion reaction. All the catalysts were synthesized and fully characterized from the structural and surface point of view (XRD, XRF, RS, BET, XPS, and FESEM) and then tested towards the oxidation of CH4 in lean conditions. The work was divided into two parts. In the first part, different catalysts at powder level were screened to optimize the design of Pd-doped cobalt spinel catalysts. In the second part, the best performing Pd-based catalysts previously selected were coated on structures of various nature (ceramic monoliths and foams) and tested towards the lean methane combustion to simulate a possible real applications (abatement of unburned CH4 residues from compressed natural gas vehicles or ventilation air methane emissions in coal mines). This thesis is organized as a collection of papers, either published during the Ph.D. or submitted for publications. In the first part (catalysts at powder level), the influence of different synthesis methods on the preparation of Pd/Co3O4 catalysts was evaluated (Paper I). Next, the role of the Pd doping on Co3O4 was investigated to determine the optimal Pd loading (Paper II). Then the Pd/Co3O4 catalyst formulation was optimized: the important catalysts' features determining the reactivity were exploited in a technologically relevant methane concentration range (Paper III). In the end, a series of cobalt iron spinels was investigated to synthesize active catalysts, with a lower content of Co, with the aim of reducing the production costs (Fe cheaper than Co) (Paper IV). As main results, the synthesis method influences the catalytic activity. Indeed, the undoped spinels synthesized by solution combustion synthesis exhibit a better activity respect to the undoped spinel synthesized via precipitation. Thus, evaluating all the informations coming from the various characterizations, the influence of the synthesis method on the catalytic activity of cobalt oxide seems to be related with its redox state. Palladium doping improves the catalytic activity independently of the synthesis method, palladium load, and CH4 inlet concentration. Indeed a complete CH4 oxidation can be reached at a temperature lower than 430 °C for undoped spinels. The addition of palladium led to the formation of a reduced cobalt oxide phase which could contribute to a generation of active oxygen species under reaction conditions. The optimal Pd load is 3wt.%, calculated as PdO. The benefit was due to the existence of well-dispersed Pd nanocrystals. At lower Pd concentrations (0.5% Pd) the amount of Pd was insufficient to catalyze CH4 combustion effectively in the applied conditions, while the specific activity was lost for higher Pd concentrations (5% Pd) because of the agglomeration of Pd nanoparticles. Finally, the addition of Fe to Co3O4 did not affect the catalytic activity of undoped catalysts, supposedly because the rate-determining step of the reaction is the activation of the C-H bond in the CH4 molecule, and apparently, Fe is not influencing the lattice oxygen stability. In the second part of the work, undoped and 3 wt.% Pd-doped cobalt spinel catalysts were deposited on monoliths and open cell foams via solution combustion synthesis using glycine as precursors. The catalyzed structures were impregnated with Pd via wetness impregnation. The catalytic activity were tested toward the methane oxidation in lean conditions, in a gas mixture containing 0.5 vol.% or 1 vol.% CH4 at three different weight hourly space velocity (30, 60, and 90 NL h-1 gcat-1). The addition of Pd improved the catalytic activity of all structures independently on the test conditions. The pressure drop and heat transfer properties were evaluated for monoliths and foams as well. The results show that the foams exhibit an higher catalytic activity than the monolith. Moreover, all the catalysts show better activity at lower weight hourly space velocity. The open cell foam based on zirconia, with the biggest average pore diameter, exhibits the best catalytic activity. In general, zirconia-based foams show a better activity than alumina and silicon carbide ones for all test conditions. In order to well understand the different behavior of the foams, pressure drop measurements and thermal conductivity tests were carried out. From these measurements, the zirconia-based foams have lower pressure drop and lower overall heat exchange coefficients than the monolith and alumina and silicon carbide foams. This aspect can be explained by the higher thermal conductivity of alumina and silicon carbide materials. In conclusion, the obtained results represent a promising scientific advance because they demonstrate the good and stable performance of a 3% Pd/Co3O4 catalyst on a zirconia-based structured support for methane combustion in adiabatic or quasi-adiabatic applications (Papers V and VI). Finally, the basic Co3O4 spinel, synthesized with different methods, was tested as an alternative anodic catalyst for the electrochemical oxygen evolution reaction, the typical reaction of an electrolyzer (Paper VII)
Influencing factors affecting the numerical simulation of the mechanized tunnel excavation using FEM and FDM techniques
No full textNumerical simulation methods have been widely applied to model the mechanized tunnel excavation for the purpose of prediction of the system behavior. This research mainly focuses on the influencing factors which may affect the simulation results of tunneling in-duced ground movements. Plaxis 3D (FEM) and FLAC 3D (FDM) are utilized to model the mechanized tunneling process by taking into account the most significant components, namely sequential excavation, face support, grouting pressure and lining installation. The differences in simulation approach between these two programs are demonstrated and the corresponding influences on the model responses are investigated as well. The soil behavior is described by using elasto-plastic Hardening Soil (HS) model which is available in both programs. It is firstly applied to small scale oedometer and triaxial element tests to validate the constitutive model in both programs. This research discusses the discrepancies in the model output due to complex soil structure interactions and intricate mechanized tunneling components subjected to these different simulation techniques. The results show that there is a good agreement between the ground movements predicted by these two programs in case of stiff soil scenario