196,376 research outputs found
Investigating maturity requirements to operate mobility as a service. The Rome case
No full textThe maturity of a city to operate a Mobility as a Service (MaaS) ecosystem has been often analyzed in the literature. This and the consideration that MaaS is mostly found in areas with longenforced transit-oriented policies and efficient multimodal supply raise the research question of whether it would be possible to operate MaaS in urban areas where mobility management is addressed according, on the contrary, to a conservative approach. A field study developed in Rome as a case in point, aimed at analyzing the actual feasibility of local MaaS operations, indicates that limitations are due to the citizens’ low willingness to pay. This is originated by a general underestimation of transit costs and made harsher by the inveterate use of passenger cars as the prevailing modal choice. The paper analyzes the results achieved, collected via a questionnaire, and highlights additional barriers to implement MaaS strictly related to its social acceptance, rather than to its technical viability, as to which the city, instead, is mature. The lesson learnt is that MaaS might be operationally (or technically) feasible even in challenging contexts, like Rome’s, but the prerequisite is to create supporting policies, for which a number of actions are outlined and elaborated, with the research goal to advance knowledge in this field, especially for decision-makers and potential stakeholders who might perceive MaaS as a too-demanding option for the context they operate in
Basamento di ancoraggio per collettore solare
No full textRelazione tecnica di progetto del basamento di un collettore solare parabolico con una superficie della parabola di 12 m^
High pressure reactive plasma spray synthesis of titanium nitride based coatings
No full textThe term thermal spray covers a wide range of fabrication methods for surface engineering applications. A very promising thermal spray,process involves the production of protective coatings or freestanding components by reactive plasma spray (RPS) techniques. Using reactive gases such as nitrogen or methane it is possible to synthesise hard nitride and carbide phases in reactive metals such as Ti, Cr, and Al. In this investigation RPS was used to produce composite titanium nitride/titanium coatings. Commercially pure titanium powders were used as raw materials and sprayed in a nitrogen atmosphere at up to 300 kPa. The process was carried out by means of a controlled atmosphere plasma spray system, allowing spraying in the pressure range 10-400 kPa. The effects of chamber pressure, plasma gas composition, and spraying distance on the scope of the expected reactions were evaluated. Phase analysis, measurements of nitrogen content and Vickers microhardness, and metallographic investigation of the as sprayed coatings revealed that titanium hard phases were synthesised during spraying and became embedded in the titanium matrix. High pressure significantly enhanced nitride formation (Ti2N, TiN, TiN1-x) in the titanium matrix. Microhardness values up to 1433 HV0.3 were obtained, with maximum nitrogen content of about 11.1 wt-%. Studies on sprayed particles showed that TiN was the dominant phase formed during flight, suggesting that diffusion processes play an important role in the substrate. Compared with pure titanium deposits, coatings produced by RPS are much harder and have better tribological properties
Law and medical ethics: in defense of reality
No full textGli autori prendono spunto da un editoriale precedente della medesima rivista per fornire spunti critici sull'assolutizzazione bioetica e biogiuridica del criterio dell'autodeterminazione individuale
Mobility as a Service in the city of Rome. Potential and feasibility
No full textThe paper presents the findings from an assessment study focused on the feasibility of developing a Mobility as a Service (MaaS) ecosystem in the city of Rome. The research goals are the identification of the target users and their willingness to pay for the different MaaS bundles proposed, and eventually the evaluation of the city's maturity to operate a MaaS ecosystem. A specific methodology is adopted, starting from a survey designed to assess MaaS knowledge and attractiveness among the Romans; data are processed, analyzed and results elaborated. The study is complemented by the outcomes from the application of a canvas business model, in order to specifically outline the service operational features. Although the implementation scenario appears to be conservative, there is still room for developing MaaS operations
COMPLEX WEAR MEASUREMENT ON THIN COATINGS BY THE CRATERING METHOD
No full textBall cratering and rotating wheel tests are useful techniques for abrasive wear resistence evaluation of thin coatings.
Nevertheless, such techniques involve significant experimental errors, coming from equipment deficiences and changes in wear response depending on test parameters.
In case of rotating wheel test, common instrumental errors are: geometry-induced errors (curved or non-horizontal sample surface), alignment errors (misalignment between ball/wheel axis and sample stage) and optical measurement errors.
In the present paper, errors due to crater dimension detection system (penetration depth or crater diameter) and equipment deficiences (rotating axes misalignment and sample slope) were numerically analysed.
A general expression form volume calculation was obtained, considering axes misalignment and sample slope, and experimentally validated by wear tests on Ti/TIN CAE-PVD coatings and profilometer abraded volumes measurement.
Results showed that axes misaligment and sample slope involve considerable errors in wear coefficient evaluation. However, errors can be corrected by the use of obtained expressions
Superconducting and microstructural studies on sputtered niobium thin films for accelerating cavity applications
No full textThe aim of the present research activity was to verify the influence of the applied bias voltage on the microstructural and functional properties of magnetron sputtering physical vapour deposition (MS-PVD) niobium thin films for use in superconducting resonant cavities for particle accelerators. Four different sets of samples were produced, by varying both the applied bias voltage and the nature of the substrate (copper or quartz). The morphological, microstructural, and mechanical properties of the coatings were experimentally determined by focused ion beam scanning electron microscopy (FIB-SEM), atomic force microscopy (AFM), transmission electron microscopy (TEM), and nanoindentation techniques, and then correlated to the applied bias and nature of the substrate. The superconducting properties (critical temperature T(c) and residual resistivity) were determined by a calibrated four-contact probe and a cryogenic apparatus. The microstructures and surface properties of biased films grown on copper and quartz were compared. The observed differences are likely connected to the low conductivity of quartz that induces a re-sputtering effect and a consequent modification of the superconducting performances
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