Condivisione e una nuova Mobilità. Il servizio Car Sharing per la città di Pisa.

La ricerca si propone di valutare l'introduzione del moderno servizio Car Sharing per la città di Pisa. Sono quindi state analizzate le necessità di spostamento dei soggetti, principalmente studenti, attraverso modelli di regressione logistica. E' stato quindi possibile delineare il profilo dell'utilizzatore tipo e dare spunti per ulteriori ricerche

Modelling and control of a flying robot interacting with the environment

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Development, Testing and Qualification of Innovative Low Viscosity Oil In Turbomachinery Applications

LecturesThe continued market demand to have more efficient machines, thus achieving energy savings and emission reductions, has motivated manufacturers to look for improvements even in area that have never been explored and evaluated till now. In this context, the authors focus the research on a high performance and high efficiency lubricant for Turbomachinery applications. New product has been formulated by a theoretical optimization of power loss reduction limiting the impact on the rotordynamic behavior. The paper reports the entire qualification process of the oil, starting from laboratory tests to certify its chemical properties, then goes through dynamic bearing test rig for the identification of stiffness and damping characteristics to finally present the results of tests on actual machinery (gas turbine, gear box and centrifugal compressor) under real operating conditions in terms of mechanical friction losses, bearing temperatures and rotordynamic behavior

Characterization of High-Power Turbomachinery Tilting Pad Journal Bearings: First Results Obtained on a Novel Test Bench

Tilting pad journal bearings are commonly used in turbomachinery for their stability at high rotational speeds. The behaviour of the bearings influences the dynamics of the rotor, so the determination of its stiffness and damping coefficients is of fundamental importance. This is often done experimentally by applying dynamic loads to the bearing and measuring the rotor/stator relative displacement. A novel experimental apparatus has been realised, in the frame of a collaboration between the Department of Civil and Industrial Engineering of the University of Pisa, GE Oil&Gas and AM Testing, to test bearings with diameters from 150 to 300 mm, with peripheral speeds up to 150 m/s, static load up to 270 kN, single tone or multitone dynamic loads up to 30 kN and frequencies up to 350 Hz. It includes very complex mechanical, hydraulic, electrical and electronic systems and requires about 1 MW of total power. In this work the first results of the static and dynamic characterization of a high performance tilting pad journal bearing of the rig are reported. Tests are typically conducted in steady conditions monitored by several sensors. Nonetheless some transient phenomena have been observed

Turbomachinery and Pump Vibrations

Discussion GroupThis group will discuss plant machinery vibration detection, monitoring, and diagnosis, from a Plant O&M point-of-view. All attendees will be encouraged (but not required) to participate in discussions, and contribute topics worthy of discussion. Likely topics presently suggested, which will be affirmed or rejected by attendee vote, include the following: • Condition monitoring vibration sensors and methods • Effectiveness of vibration condition monitoring on rotating equipment for detecting problems • “Diagnostics” versus “prognostics” • Value of, and ROI of, condition-based monitoring of vibration • Vertical pump monitoring, including below ground monitoring • Vibration standards for various pumps and turbomachinery types, sizes, and applications • Vibration test method options, and their proper selection and use • Standard locations for vibration measurement on machinery • Wireless devices: radio noise, effectiveness, experiences, security • Troubleshooting methods for typical vibration problems, and fix options • Operating Deflection Shapes and integration with condition-based monitoring • Finite element analysis application in support of machinery selection and troubleshooting • Rotordynamics analysis use in machinery selection and troubleshooting • Hydraulically-induced vibration: structural, system, rotor, acoustic • Measurement of presence, location, and severity of pump cavitation • Effect of high GVF (gas volume fraction) in centrifugal pumps • Mechanical installation (e.g. piping, foundation, alignment) issues affecting vibration • Seal and bearing effects on vibration, and vibration effects on bearings and seal

New Approach To Torsional Vibration Monitoring

Lecturepg. 60-71This paper presents a summary of the authors' experience gained from implementation of model-based monitoring systems for LNG string vibration. The development of a novel train torsional vibration monitoring approach utilizing system modal analysis and lateral-torsional coupling in geared systems has been reported. A number of recent Root Cause Analysis programs related to turbocompressor string operation problems (LNG production) have faced barriers due to lack of adequate torsional vibration monitoring solutions. As the machinery problems associated with abnormal levels of train torsional vibration become more frequent, the incentives for the Oil & Gas industry to address the need for reliable and trouble-free cyclic torque evaluation gain ground. This constitutes a demand for a robust, reliable and accurate torsional vibration monitoring approach acceptable as a practical solution. Contemporary, industry-wide accepted measurement technologies (strain gage with telemetry, optical probes, laser) fit the test needs well but their lack of ruggedness and durability as well as problematic installation impacting machine operation do not permit their consideration for long-term monitoring applications. The authors present a methodology which allows evaluation of alternating torque amplitudes in different string sections based on standard instrumentation installed on the train. The approach adopted in this paper relies heavily on the modal representation of the dynamic system being analyzed. The calculation method described utilizes the results of such analysis along with the angular vibration signal obtained from standard instrumentation installed on the train (gas turbine speed pick-up signal spectrum) and typical radial vibration data from gearbox proximity probes (when available). This means that no additional probes need to be installed to get the results. The robustness and accuracy of the proposed techniques was validated in the laboratory and benchmarked against test data from several LNG production train measurement campaigns, where the alternating torque was measured by means of standard measurement systems. The authors show the results of this verification together with prospective system applications. The symbols and abbreviations used in this paper are given in the last section

Feasibility and usefulness of ultrasonography in idiopathic intracranial hypertension or secondary intracranial hypertension

Transorbital sonography (TOS) has been proven to be able to non-invasively detect elevated intracranial pressure. In this condition TOS shows an increase in optic nerve sheath diameter (ONSD). It has been suggested that internal jugular vein valve insufficiency (IJVVI) may represent a factor contributing to the pathogenesis of idiopathic intracranial hypertension (IIH). The aim of this study was to investigate whether patients with IIH or secondary IH have higher ONSD values and higher frequency of IJVVI compared to subjects without IH

Turbomachinery and Pump Vibrations

Discussion GroupThis group will discuss plant machinery vibration detection, monitoring, and diagnosis, from a Plant O&M point-of-view. All attendees will be encouraged (but not required) to participate in discussions, and contribute topics worthy of discussion. Likely topics presently suggested, which will be affirmed or rejected by attendee vote, include the following: • Condition monitoring vibration sensors and methods • Effectiveness of vibration condition monitoring on rotating equipment for detecting problems • “Diagnostics” versus “prognostics” • Value of, and ROI of, condition-based monitoring of vibration • Vertical pump monitoring, including below ground monitoring • Vibration standards for various pumps and turbomachinery types, sizes, and applications • Vibration test method options, and their proper selection and use • Standard locations for vibration measurement on machinery • Wireless devices: radio noise, effectiveness, experiences, security • Troubleshooting methods for typical vibration problems, and fix options • Operating Deflection Shapes and integration with condition-based monitoring • Finite element analysis application in support of machinery selection and troubleshooting • Rotordynamics analysis use in machinery selection and troubleshooting • Hydraulically-induced vibration: structural, system, rotor, acoustic • Measurement of presence, location, and severity of pump cavitation • Effect of high GVF (gas volume fraction) in centrifugal pumps • Mechanical installation (e.g. piping, foundation, alignment) issues affecting vibration • Seal and bearing effects on vibration, and vibration effects on bearings and seal

Longitudinal Assessment of Transorbital Sonography, Visual Acuity, and Biomarkers for Inflammation and Axonal Injury in Optic Neuritis

Background and Objective. To investigate the relationship between optic nerve sheath diameter, optic nerve diameter, visual acuity and osteopontin, and neurofilament heavy chain in patients with acute optic neuritis. Patients and Methods. Sonographic and visual acuity assessment and biomarker measurements were executed in 23 patients with unilateral optic neuritis and in 19 sex- and age-matched healthy controls. Results. ONSD was thicker on the affected side at symptom onset (median 6.3 mm; interquartile range 6.0–6.5) than after 12 months (5.3 mm; 4.9–5.6; p<0.001) or than in controls (5.2 mm; 4.8–5.5; p<0.001). OND was significantly increased in the affected side (3.4 mm; 2.9–3.8) compared to healthy controls (2.7 mm; 2.5–2.9; p<0.001) and was thicker at baseline than after 12 months (2.8 mm; 2.7–3.0; p<0.01). Visual acuity improved significantly after 12 months (1.00; 0.90–1.00) compared to onset of symptoms (0.80; 0.40–1.00; p<0.001). OPN levels were significantly higher in patients at presentation (median 6.44 ng/ml; 2.05–10.06) compared to healthy controls (3.21 ng/ml, 1.34–4.34; p<0.03). Concentrations of NfH were significantly higher in patients than in controls. Conclusion. ONSD and OND are increased in the affected eye. OPN and NfH are elevated in patients, confirming the presence of any underlying inflammation and axonal injury

Longitudinal assessment of transorbital sonography, visual acuity, and biomarkers for inflammation and axonal injury in optic neuritis

BACKGROUND AND OBJECTIVE: To investigate the relationship between optic nerve sheath diameter, optic nerve diameter, visual acuity and osteopontin, and neurofilament heavy chain in patients with acute optic neuritis. PATIENTS AND METHODS: Sonographic and visual acuity assessment and biomarker measurements were executed in 23 patients with unilateral optic neuritis and in 19 sex- and age-matched healthy controls. RESULTS: ONSD was thicker on the affected side at symptom onset (median 6.3\u2009mm; interquartile range 6.0-6.5) than after 12 months (5.3\u2009mm; 4.9-5.6; p < 0.001) or than in controls (5.2\u2009mm; 4.8-5.5; p < 0.001). OND was significantly increased in the affected side (3.4\u2009mm; 2.9-3.8) compared to healthy controls (2.7\u2009mm; 2.5-2.9; p < 0.001) and was thicker at baseline than after 12 months (2.8\u2009mm; 2.7-3.0; p < 0.01). Visual acuity improved significantly after 12 months (1.00; 0.90-1.00) compared to onset of symptoms (0.80; 0.40-1.00; p < 0.001). OPN levels were significantly higher in patients at presentation (median 6.44\u2009ng/ml; 2.05-10.06) compared to healthy controls (3.21\u2009ng/ml, 1.34-4.34; p < 0.03). Concentrations of NfH were significantly higher in patients than in controls. CONCLUSION: ONSD and OND are increased in the affected eye. OPN and NfH are elevated in patients, confirming the presence of any underlying inflammation and axonal injury