Condition assessment of in situ elastomeric bearings

2021 ◽  
Author(s):  
Edoardo Rossi ◽  
Michele D’Amato ◽  
Rosario Gigliotti ◽  
Marco Sebastiani
Keyword(s):  
Modal Analysis ◽  
Extreme Events ◽  
Seismic Isolation ◽  
Operational Modal Analysis ◽  
Structural Components ◽  
Long Term Effects ◽  
Elastomeric Bearings ◽  
Very High

<p>Elastomeric bearings used as seismic isolation devices are key elements in the protection of constructions against earthquakes. They enable structures to exhibit very high performances when subject to extreme events, preventing damage both to structural and non-structural components. Their characteristics, however, are prone to change with time due to long term effects such as aging. Regular inspection and monitoring of their state are thus fundamental activities needed to ensure the required performances. The present work reviews the most common strategies adopted for such purpose, including visual inspections, Operational Modal Analysis (OMA), and quick release tests. An innovative characterisation method is also presented. Such method, with the use of a nanoindenter, enables testing of a small rubber sample (3 mm in diameter) cored from a device. Its suitability is confirmed through a comparison of the same device tested in a traditional setup.</p>

scholarly journals Non-Invasive Parameter Identification in Rotordynamics via Fluid Film Bearings: Linking Active Lubrication and Operational Modal Analysis

2016 ◽  
Author(s):  
Ilmar Ferreira Santos ◽  
Peter Kjær Svendsen
Keyword(s):  
Parameter Identification ◽  
Modal Analysis ◽  
Natural Frequencies ◽  
Transfer Functions ◽  
Injection Pressure ◽  
Operational Modal Analysis ◽  
Fluid Film ◽  
Non Invasive ◽  
Fluid Film Bearings

In recent years, theoretical and experimental efforts have transformed the conventional tilting-pad journal bearing (TPJB) into a smart mechatronic machine element. The application of electromechanical elements into rotating systems makes feasible the generation of controllable forces over the rotor as a function of a suitable control signal. The servovalve input signal and the radial injection pressure are the two main parameters responsible for dynamically modifying the journal oil film pressure and generating active fluid film forces in controllable fluid film bearings. Such fluid film forces, resulting from a strong coupling between hydrodynamic, hydrostatic and controllable lubrication regimes, can be used either to control or to excite rotor lateral vibrations. If non-invasive forces are generated via lubricant fluid film, in situ parameter identification can be carried out, enabling evaluation of the mechanical condition of the rotating machine. Using the lubricant fluid film as a non-invasive calibrated shaker is troublesome, once several transfer functions among mechanical, hydraulic and electronic components become necessary. In this framework the main original contribution of this paper is to show experimentally that the knowledge about the several transfer functions can be bypassed by using output-only identification techniques. The manuscript links controllable (active) lubrication techniques with operational modal analysis, allowing for in-situ parameter identification in rotordynamics, i.e. estimation of damping ratio and natural frequencies. The experimental analysis is carried out on a rigid rotor-level system supported by one single pair of pads. The estimation of damping and natural frequencies is performed using classical experimental modal analysis (EMA) and operational modal analysis (OMA). Very good agreements between the two experimental approaches are found. Maximum values of the main input parameters, namely servovalve voltage and radial injection pressure, are experimentally found with the objective of defining ranges of non-invasive perturbation forces.

scholarly journals A Framework to Advance the Understanding of the Ecological Effects of Extreme Climate Events

2019 ◽  
Vol 11 (21) ◽  
pp. 5954 ◽  
Author(s):  
Carlos Sanz-Lazaro
Keyword(s):  
Climate Change ◽  
Extreme Events ◽  
Ecological Effects ◽  
Rocky Shores ◽  
Long Term Effects ◽  
Starting Point ◽  
Experimental Approaches ◽  
Key Aspects ◽  
Climate Events

Climate change is modifying disturbance regimes, affecting the severity and occurrence of extreme events. Current experiments investigating extreme events have a large diversity of experimental approaches and key aspects such as the interaction with other disturbances, the timing, and long-term effects are not usually incorporated in a standardized way. This lack of comparability among studies limits advances in this field of research. This study presents a framework that is comprised of two experimental approaches designed to test expected changes on disturbance regime due to climate change. These approaches test the effects of disturbances becoming more clustered and more extreme. They use common descriptor variables regardless of the type of disturbance and ecosystem. This framework is completed with a compilation of procedures that increase the realism of experiments in the aforementioned key aspects. The proposed framework favours comparability among studies and increases our understanding of extreme events. Examples to implement this framework are given using rocky shores as a case study. Far from being perfect, the purpose of this framework is to act as a starting point that triggers the comparability and refinement of these types of experiments needed to advance our understanding of the ecological effects of extreme events.

scholarly journals Comparison of Radiographic and Surface Topography Measurements in Adolescents with Idiopathic Scoliosis

2012 ◽  
Vol 6 (1) ◽  
pp. 261-265 ◽  
Author(s):  
Jason M Frerich ◽  
Kristen Hertzler ◽  
Patrick Knott ◽  
Steven Mardjetko
Keyword(s):  
Idiopathic Scoliosis ◽  
Surface Topography ◽  
Gold Standard ◽  
Comparison Analysis ◽  
Long Term Effects ◽  
Radiographic Measurements ◽  
Curve Magnitude ◽  
Standard Radiographs ◽  
Very High

Purpose: In patients with adolescent idiopathic scoliosis (AIS), radiographic surveillance is the gold standard of assessing spinal deformity, but has negative long-term effects. The Formetric 4D surface topography system was compared to standard radiography as a safer option for evaluating patients with AIS. Methods: Fourteen volunteers with typical AIS patient stature had 30 repeated Formetric 4D measurements taken, and reproducibility was assessed. Sixty-four patients with AIS were then enrolled during routine clinic visits. Evaluation included standard radiographs and surface topography measurements. A comparison analysis was performed. Results: When assessing same-day repeated scans, a standard deviation of +/- 3.4 degrees for scoliosis curve measurements was determined, and the Reliability Coefficient (Cronbach) was very high (0.996). Cobb angles measured with the Formetric 4D differed from radiographic measurements by an average of 9.42 (lumbar) and 6.98 (thoracic) degrees, while the correlation between the two measurements was strong (95% confidence interval [CI]), 0.758 (lumbar) and 0.872 (thoracic) respectively. Conclusions: The Formetric 4D is comparable to radiography in terms of its test-retest reproducibility. Although this device does not predict curve magnitude exactly, the predictions correlate strongly with the Cobb angles determined from radiographs. It can be reliably used in the surveillance of patients with AIS.

scholarly journals Primary Extracellular Matrix Enables Long-Term Cultivation of Human Tumor Oral Mucosa Models

2020 ◽  
Vol 8 ◽  
Author(s):  
Leonie Gronbach ◽  
Philipp Jurmeister ◽  
Monika Schäfer-Korting ◽  
Ulrich Keilholz ◽  
Ingeborg Tinhofer ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Oral Mucosa ◽  
Hypoxia Inducible Factor ◽  
Human Tumor ◽  
Patient Specific ◽  
Long Term Effects ◽  
Tumor Models

3D tumor models clearly outperform 2D cell cultures in recapitulating tissue architecture and drug response. However, their potential in understanding treatment efficacy and resistance development should be better exploited if also long-term effects of treatment could be assessed in vitro. The main disadvantages of the matrices commonly used for in vitro culture are their limited cultivation time and the low comparability with patient-specific matrix properties. Extended cultivation periods are feasible when primary human cells produce the extracellular matrix in situ. Herein, we adapted the hyalograft-3D approach from reconstructed human skin to normal and tumor oral mucosa models and compared the results to bovine collagen-based models. The hyalograft models showed similar morphology and cell proliferation after 7 weeks compared to collagen-based models after 2 weeks of cultivation. Tumor thickness and VEGF expression increased in hyalograft-based tumor models, whereas expression of laminin-332, tenascin C, and hypoxia-inducible factor 1α was lower than in collagen-based models. Taken together, the in situ produced extracellular matrix better confined tumor invasion in the first part of the cultivation period, with continuous tumor proliferation and increasing invasion later on. This proof-of-concept study showed the successful transfer of the hyalograft approach to tumor oral mucosa models and lays the foundation for the assessment of long-term drug treatment effects. Moreover, the use of an animal-derived extracellular matrix is avoided.

Long-term effects of bacille calmette-guérin perfusion therapy for treatment of transitional cell carcinoma in situ of upper urinary tract

Urology ◽  
2004 ◽  
Vol 63 (6) ◽  
pp. 1084-1088 ◽  
Author(s):  
Yasushi Hayashida ◽  
Koichiro Nomata ◽  
Mitsuru Noguchi ◽  
Jiro Eguchi ◽  
Sigehiko Koga ◽  
...  
Keyword(s):  
Urinary Tract ◽  
Transitional Cell Carcinoma ◽  
Cell Carcinoma ◽  
Carcinoma In Situ ◽  
Transitional Cell ◽  
Upper Urinary Tract ◽  
Long Term Effects ◽  
Bacille Calmette Guerin

LONG-TERM EFFECTS OF BACILLUS CALMETTE-GUERIN PERFUSION THERAPY FOR UPPER URINARY TRACT UROTHELIAL CARCINOMA IN SITU

2008 ◽  
Vol 179 (4S) ◽  
pp. 120-120
Author(s):  
Takahiro Yoneyama ◽  
Hayato Yamamoto ◽  
Akiko Okamoto ◽  
Atsushi Imai ◽  
Ikuya Iwabuchi ◽  
...  
Keyword(s):  
Urinary Tract ◽  
Urothelial Carcinoma ◽  
Carcinoma In Situ ◽  
Upper Urinary Tract ◽  
Bacillus Calmette Guerin ◽  
Long Term Effects ◽  
Urinary Tract Urothelial Carcinoma

scholarly journals Twenty-Five and Thirty-Five Year Follow up of First Admissions to Mental Hospital

1968 ◽  
Vol 13 (3) ◽  
pp. 219-229 ◽  
Author(s):  
M. N. Beck
Keyword(s):  
Prince Edward Island ◽  
Mental Hospital ◽  
Long Term Effects ◽  
Nineteen Thirties ◽  
Needed Information ◽  
Nineteen Forties ◽  
Long Term Follow Up ◽  
Very High

This has been a report of a study designed to assess the feasibility of long-term follow-up studies on Prince Edward Island. Cohorts of patients first admitted to the Island's only mental hospital during the early nineteen-thirties and early nineteen-forties were followed in retrospect in order to determine, a) the course and outcome of the major disorders over periods ranging up to thirty-five years and, b) the long-term effects of these disorders upon the families of the patients. Needed information was gathered through a review of hospital records, a search for death records and community interviews. The results of the study suggest that lifetime prognosis in the absence of modern treatment methods may be even worse than believed by most professionals working in the field. As might be expected the outlook was found to be particularly grave for schizophrenia. Success in following up a very high proportion of the cases over several decades supports the belief that Prince Edward Island offers unusual opportunities for studies of this kind.

In situ characterization of metals at extremes

MRS Bulletin ◽  
2010 ◽  
Vol 35 (12) ◽  
pp. 1009-1016 ◽  
Author(s):  
N. D. Browning ◽  
G. H. Campbell ◽  
J. A. Hawreliak ◽  
M. A. Kirk
Keyword(s):  
Structural Evolution ◽  
Extreme Conditions ◽  
Long Term Effects ◽  
Recent Developments ◽  
Definition Of ◽  
Radiation Conditions ◽  
Temperature Strain

The fundamental processes taking place in metals under extreme conditions can occur on ultrafast timescales (i.e., nanoseconds to picoseconds), and yet their result can continue to have a significant impact on the structural properties for many years to follow. The challenge in developing in situ methods for characterization under extreme conditions therefore involves both the modification of the instrumentation to implement the high-temperature, strain, and radiation conditions and the definition of the timescale over which the measurement must be made. While techniques are well established for characterization of the long-term effects of extreme conditions, experiments are only just beginning to probe the initial stages of structural evolution. This article reviews recent developments in optical, x-ray, and electron probes of metals under extreme conditions and also discusses the needs for future experiments and potential pathways to achieving these goals.

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