44 research outputs found
Hydrodynamic air lubricated compliant surface bearing for an automotive gas turbine engine. 2: Materials and coatings
Material coatings for an air-lubricated, compliant journal bearing for an automotive gas turbine engine were exposed to service test temperatures of 540 C or 650 C for 300 hours, and to 10 temperature cycles from room temperatures to the service test temperatures. Selected coatings were then put on journal and partial-arc foils and tested in start-stop cycle tests at 14 kPa (2 psi) loading for 2000 cycles. Half of the test cycles were performed at a test chamber service temperature of 540 C (1000 F) or 650 C (1200 F); the other half were performed at room temperature. Based on test results, the following combinations and their service temperature limitations are recommended: HL-800 TM (CdO and graphite) on foil versus chrome carbide on journal up to 370 C (700 F); NASA PS 120 (Tribaloy 400, silver and CaF2 on journal versus uncoated foil up to 540 C (1000 F); and Kaman DES on journal and foil up to 640 C (1200 F). Kaman DES coating system was further tested successfully at 35 kPa (5 psi) loading for 2000 start-stop cycles
Hydrodynamic air lubricated compliant surface bearing for an automotive gas turbine engine. 1: Journal bearing performance
A 38.1 mm (1.5 inch) diameter Hydresil Compliant Surface Air Lubricated Journal Bearing was designed and tested to obtain bearing performance characteristics at both room temperature and 315 C (600 F). Testing was performed at various speeds up to 60,000 rpm with varying loads. Rotating sensors provided an opportunity to examine the film characteristics of the compliant surface bearing. In addition to providing minimum film thickness values and profiles, many other insights into bearing operation were gained such as the influence of bearing fabrication accuracy and the influence of smooth foil deflection between the bumps
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THE EFFECT OF THERMAL CONDITIONS ON PROCESS DEFECTS IN ELECTRON BEAM DIRECTED ENERGY DEPOSITION
Observing process defects at size scales and with sufficient confidence relevant to qualification
efforts has not yet been achieved in metal AM, so non-destructive testing (NDT) techniques are
used to detect porosity within material deposited. NDT costs can be significant and may not
achieve targeted resolution due to geometry and material limitations. In this work, in-process
monitoring of Electron Beam Directed Energy Deposition (EB-DED) is enhanced to include
three thermal history conditions; inter-pass, melt pool superheat and trailing bead temperatures.
Quality scenarios are applied to simulate various process conditions during EB-DED at three
different thermal conditions within production relevant use cases and resultant process defects
are characterized via high throughput computed tomography. Defects are spatially and
temporally registered to process conditions observed during EB-DED and statistically mapped to
thermal scenarios. Thermal condition has a strong influence on the quantity of observed process
defects, with lower interpass temperature resulting in a larger number of defects.Mechanical Engineerin
Cyclic vomiting syndrome in children: a nationwide survey of current practice on behalf of the Italian Society of Pediatric Gastroenterology, Hepatology and Nutrition (SIGENP) and Italian Society of Pediatric Neurology (SINP)
Background: Cyclic Vomiting Syndrome (CVS) is a rare functional gastrointestinal disorder, which has a considerable burden on quality of life of both children and their family. Aim of the study was to evaluate the diagnostic modalities and therapeutic approach to CVS among Italian tertiary care centers and the differences according to subspecialties, as well as to explore whether potential predictive factors associated with either a poor outcome or a response to a specific treatment. Methods: Cross-sectional multicenter web-based survey involving members of the Italian Society of Pediatric Gastroenterology, Hepatology and Nutrition (SIGENP) and Italian Society of Pediatric Neurology (SINP). Results: A total of 67 responses were received and analyzed. Most of the respondent units cared for less than 20 patients. More than half of the patients were referred after 3 to 5 episodes, and a quarter after 5 attacks. We report different diagnostic approaches among Italian clinicians, which was particularly evident when comparing gastroenterologists and neurologists. Moreover, our survey demonstrated a predilection of certain drugs during emetic phase according to specific clinic, which reflects the cultural background of physicians. Conclusion: In conclusion, our survey highlights poor consensus amongst clinicians in our country in the diagnosis and the management of children with CVS, raising the need for a national consensus guideline in order to standardize the practice
Characteristics and patterns of care of endometrial cancer before and during COVID-19 pandemic
Objective: Coronavirus disease 2019 (COVID-19) outbreak has correlated with the disruption of screening activities and diagnostic assessments. Endometrial cancer (EC) is one of the most common gynecological malignancies and it is often detected at an early stage, because it frequently produces symptoms. Here, we aim to investigate the impact of COVID-19 outbreak on patterns of presentation and treatment of EC patients. Methods: This is a retrospective study involving 54 centers in Italy. We evaluated patterns of presentation and treatment of EC patients before (period 1: March 1, 2019 to February 29, 2020) and during (period 2: April 1, 2020 to March 31, 2021) the COVID-19 outbreak. Results: Medical records of 5,164 EC patients have been retrieved: 2,718 and 2,446 women treated in period 1 and period 2, respectively. Surgery was the mainstay of treatment in both periods (p=0.356). Nodal assessment was omitted in 689 (27.3%) and 484 (21.2%) patients treated in period 1 and 2, respectively (p<0.001). While, the prevalence of patients undergoing sentinel node mapping (with or without backup lymphadenectomy) has increased during the COVID-19 pandemic (46.7% in period 1 vs. 52.8% in period 2; p<0.001). Overall, 1,280 (50.4%) and 1,021 (44.7%) patients had no adjuvant therapy in period 1 and 2, respectively (p<0.001). Adjuvant therapy use has increased during COVID-19 pandemic (p<0.001). Conclusion: Our data suggest that the COVID-19 pandemic had a significant impact on the characteristics and patterns of care of EC patients. These findings highlight the need to implement healthcare services during the pandemic
Practice patterns and 90-day treatment-related morbidity in early-stage cervical cancer
To evaluate the impact of the Laparoscopic Approach to Cervical Cancer (LACC) Trial on patterns of care and surgery-related morbidity in early-stage cervical cancer
Thromboelastometry versus standard coagulation tests versus restrictive protocol to guide blood transfusion prior to central venous catheterization in cirrhosis: study protocol for a randomized controlled trial
The stratigraphic architecture of Bolognano Fm in the eastern Majella: implication for environmental and climatic evolution of the central paleo-Adriatic domain.
FREQUENCIES AT CD4, FES AND F13A1 MICROSATELLITE LOCI IN CENTRAL-SOUTHERN SARDINIA (ITALY)
Frequencies at CD4, FES, and F13A1 microsatellite loci in central-southern Sardinia (Italy)
We have analyzed the distribution of allele frequencies at three microsatellite loci (CD4, FES, and F13A1) among individuals living and born in central-southern Sardinia (Italy), in a zone called "Trexenta" within the province of Cagliari (n = 50). This area has been already studied from the linguistic and genetic point of view (1) using classical polymorphism at protein level. Informed consent was obtained from all donors