199 research outputs found
Forced response of rotating bladed disks: Blade Tip-Timing measurements
The Blade Tip-Timing is a well-known non-contact measurement technique currently employed
for the identification of the dynamic behaviours of rotating bladed disks. Although the
measurement system has become a typical industry equipment for bladed disks vibration
surveys, the type of sensors, the positioning of the sensors around the bladed disk and the used
algorithm for data post-processing are still not standard techniques, and their reliability has to
be proved for different operation conditions by the comparison with other well-established
measurement techniques used as reference like strain gauges. This paper aims at evaluating the
accuracy of a latest generation Tip-Timing system on two dummy blisks characterized by
different geometrical, structural and dynamical properties. Both disks are tested into a spin-rig
where a fixed number of permanent magnets excite synchronous vibrations with respect to the
rotor speed. A new positioning for the Blade Tip-Timing optical sensors is tested in the case of a
shrouded bladed disk. Due to the presence of shrouds, the sensors cannot be positioned at the
outer radius of the disk pointing radially toward the rotation axis as in the most common
applications, since the displacements at the tips are very small and cannot be detected. For this
reason a particular placement of optical laser sensors is studied in order to point at the leading
and trailing edges' locations where the blades experience the largest vibration amplitudes with
the aim of not interfering with the flow path. Besides the typical Blade Tip-Timing application
aimed at identifying the dynamical properties of each blade, an original method is here proposed
to identify the operative deflection shape of a bladed disk through the experimental determination
of the nodal diameters. The method is applicable when a small mistuning pattern perturbs
the ideal cyclic symmetry of the bladed disk
Synchronous vibration parameters identification by tip timing measurements
The Blade Tip Timing (BTT) measurement system is a technique to measure vibration parameters of a rotating bladed disk. In particular for synchronous vibrations the BTT provides signals versus the rotation speed of the disk starting from the measurement of the time of arrival (TOA) of each blade under the tip timing probes. The signals must be post processed in order to obtain the interesting parameters of each blade vibration. The paper presents a method to extract the main parameters (amplitude and frequency) in resonance condition from the tip timing measurements. The proposed method is a revision of the already existing well known Two-Parameter Plot (2PP) method which requires a minimum of two probes. Improvements to the existing 2PP method are here suggested mainly in the part of engine order identification.
The proposed method is then applied to the BTT measured signals coming from a rotating bladed disk excited at different engine orders. At the same time on the disk the vibration of one blade was detected by strain gauges. The strain gauges were calibrated and they provide the reference values of the vibration parameters. The vibration parameters derived by the proposed method are in agreement with those obtained by the strain gages methodolog
Forced response of rotating bladed disks: Blade Tip-Timing measurements
The Blade Tip-Timing is a well-known non-contact measurement technique currently employed
for the identification of the dynamic behaviours of rotating bladed disks. Although the
measurement system has become a typical industry equipment for bladed disks vibration
surveys, the type of sensors, the positioning of the sensors around the bladed disk and the used
algorithm for data post-processing are still not standard techniques, and their reliability has to
be proved for different operation conditions by the comparison with other well-established
measurement techniques used as reference like strain gauges. This paper aims at evaluating the
accuracy of a latest generation Tip-Timing system on two dummy blisks characterized by
different geometrical, structural and dynamical properties. Both disks are tested into a spin-rig
where a fixed number of permanent magnets excite synchronous vibrations with respect to the
rotor speed. A new positioning for the Blade Tip-Timing optical sensors is tested in the case of a
shrouded bladed disk. Due to the presence of shrouds, the sensors cannot be positioned at the
outer radius of the disk pointing radially toward the rotation axis as in the most common
applications, since the displacements at the tips are very small and cannot be detected. For this
reason a particular placement of optical laser sensors is studied in order to point at the leading
and trailing edges' locations where the blades experience the largest vibration amplitudes with
the aim of not interfering with the flow path. Besides the typical Blade Tip-Timing application
aimed at identifying the dynamical properties of each blade, an original method is here proposed
to identify the operative deflection shape of a bladed disk through the experimental determination
of the nodal diameters. The method is applicable when a small mistuning pattern perturbs
the ideal cyclic symmetry of the bladed disk
Synchronous vibration parameters identification by tip timing measurements
The Blade Tip Timing (BTT) measurement system is a technique to measure vibration parameters of a rotating bladed disk. In particular for synchronous vibrations the BTT provides signals versus the rotation speed of the disk starting from the measurement of the time of arrival (TOA) of each blade under the tip timing probes. The signals must be post processed in order to obtain the interesting parameters of each blade vibration. The paper presents a method to extract the main parameters (amplitude and frequency) in resonance condition from the tip timing measurements. The proposed method is a revision of the already existing well known Two-Parameter Plot (2PP) method which requires a minimum of two probes. Improvements to the existing 2PP method are here suggested mainly in the part of engine order identification.
The proposed method is then applied to the BTT measured signals coming from a rotating bladed disk excited at different engine orders. At the same time on the disk the vibration of one blade was detected by strain gauges. The strain gauges were calibrated and they provide the reference values of the vibration parameters. The vibration parameters derived by the proposed method are in agreement with those obtained by the strain gages methodolog
Natural History of Malignant Bone Disease in Renal Cancer: Final Results of an Italian Bone Metastasis Survey
Abstract Background: Bone metastasis represents an increasing clinical problem in advanced renal cell carcinoma (RCC) as diseaserelated survival improves. There are few data on the natural history of bone disease in RCC
The rapid spread of SARS-COV-2 Omicron variant in Italy reflected early through wastewater surveillance
The SARS-CoV-2 Omicron variant emerged in South Africa in November 2021, and has later been identified worldwide, raising serious concerns. A real-time RT-PCR assay was designed for the rapid screening of the Omicron variant, targeting characteristic mutations of the spike gene. The assay was used to test 737 sewage samples collected throughout Italy (19/21 Regions) between 11 November and 25 December 2021, with the aim of assessing the spread of the Omicron variant in the country. Positive samples were also tested with a real-time RT-PCR developed by the European Commission, Joint Research Centre (JRC), and through nested RT-PCR followed by Sanger sequencing. Overall, 115 samples tested positive for Omicron SARS-CoV-2 variant. The first occurrence was detected on 7 December, in Veneto, North Italy. Later on, the variant spread extremely fast in three weeks, with prevalence of positive wastewater samples rising from 1.0% (1/104 samples) in the week 5-11 December, to 17.5% (25/143 samples) in the week 12-18, to 65.9% (89/135 samples) in the week 19-25, in line with the increase in cases of infection with the Omicron variant observed during December in Italy. Similarly, the number of Regions/Autonomous Provinces in which the variant was detected increased from one in the first week, to 11 in the second, and to 17 in the last one. The presence of the Omicron variant was confirmed by the JRC real-time RT-PCR in 79.1% (91/115) of the positive samples, and by Sanger sequencing in 66% (64/97) of PCR amplicons. In conclusion, we designed an RT-qPCR assay capable to detect the Omicron variant, which can be successfully used for the purpose of wastewater-based epidemiology. We also described the history of the introduction and diffusion of the Omicron variant in the Italian population and territory, confirming the effectiveness of sewage monitoring as a powerful surveillance tool
The rapid spread of SARS-COV-2 Omicron variant in Italy reflected early through wastewater surveillance
The SARS-CoV-2 Omicron variant emerged in South Africa in November 2021, and has later been identified worldwide,
raising serious concerns.
A real-time RT-PCR assay was designed for the rapid screening of the Omicron variant, targeting characteristic mutations
of the spike gene. The assay was used to test 737 sewage samples collected throughout Italy (19/21 Regions) between
11 November and 25 December 2021, with the aim of assessing the spread of the Omicron variant in the
country. Positive samples were also tested with a real-time RT-PCR developed by the European Commission, Joint
Research Centre (JRC), and through nested RT-PCR followed by Sanger sequencing.
Overall, 115 samples tested positive for Omicron SARS-CoV-2 variant. The first occurrence was detected on 7
December, in Veneto, North Italy. Later on, the variant spread extremely fast in three weeks, with prevalence of positive
wastewater samples rising from 1.0% (1/104 samples) in the week 5–11 December, to 17.5% (25/143 samples)
in the week 12–18, to 65.9% (89/135 samples) in the week 19–25, in line with the increase in cases of infection with
the Omicron variant observed during December in Italy. Similarly, the number of Regions/Autonomous Provinces in
which the variant was detected increased fromone in the first week, to 11 in the second, and to 17 in the last one. The
presence of the Omicron variant was confirmed by the JRC real-time RT-PCR in 79.1% (91/115) of the positive samples,
and by Sanger sequencing in 66% (64/97) of PCR amplicons
Disease-specific and general health-related quality of life in newly diagnosed prostate cancer patients: The Pros-IT CNR study
Background: The National Research Council (CNR) prostate cancer monitoring project in Italy (Pros-IT CNR) is an observational, prospective, ongoing, multicentre study aiming to monitor a sample of Italian males diagnosed as new cases of prostate cancer. The present study aims to present data on the quality of life at time prostate cancer is diagnosed. Methods: One thousand seven hundred five patients were enrolled. Quality of life is evaluated at the time cancer was diagnosed and at subsequent assessments via the Italian version of the University of California Los Angeles-Prostate Cancer Index (UCLA-PCI) and the Short Form Health Survey (SF-12). Results: At diagnosis, lower scores on the physical component of the SF-12 were associated to older ages, obesity and the presence of 3+ moderate/severe comorbidities. Lower scores on the mental component were associated to younger ages, the presence of 3+ moderate/severe comorbidities and a T-score higher than one. Urinary and bowel functions according to UCLA-PCI were generally good. Almost 5% of the sample reported using at least one safety pad daily to control urinary loss; less than 3% reported moderate/severe problems attributable to bowel functions, and sexual function was a moderate/severe problem for 26.7%. Diabetes, 3+ moderate/severe comorbidities, T2 or T3-T4 categories and a Gleason score of eight or more were significantly associated with lower sexual function scores at diagnosis. Conclusions: Data collected by the Pros-IT CNR study have clarified the baseline status of newly diagnosed prostate cancer patients. A comprehensive assessment of quality of life will allow to objectively evaluate outcomes of different profile of care
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