scholarly journals Long-term extreme buffeting response of cable-supported bridges with uncertain turbulence parameters

2021 ◽  
Vol 236 ◽  
pp. 112126
Author(s):  
Tor M. Lystad ◽  
Aksel Fenerci ◽  
Ole Øiseth
Keyword(s):  
Buffeting Response ◽  
Turbulence Parameters

Long-term extreme buffeting response of long-span bridges considering uncertain turbulence parameters

2021 ◽  
Author(s):  
Tor Martin Lystad ◽  
Aksel Fenerci ◽  
Ole Øiseth
Keyword(s):  
Short Term ◽  
Long Span Bridges ◽  
Buffeting Response ◽  
Long Span ◽  
Long Span Bridge ◽  
Extreme Response ◽  
Current Design ◽  
Extreme Responses ◽  
Turbulence Parameters

<p>Long-term extreme response analyses are recognized as the most accurate way to predict the extreme responses of marine structures excited by stochastic environmental loading. In wind engineering for long-span bridges this approach has not become the standard method to estimate the extreme responses. Instead, the design value is often estimated as the expected extreme response from a short-term storm described by an N-year return period mean wind velocity.</p><p>In this study, the long-term extreme buffeting response of a long-span bridge is investigated, and the uncertainty of the turbulent wind field is described by a probabilistic model. The results indicate that the current design practice may introduce significant uncertainty to the buffeting load effects used in design, when the variability in the turbulence parameters as well as the uncertainty of the short-term extreme response is neglected.</p>

scholarly journals Dome C site testing: long term statistics of integrated optical turbulence parameters at ground level

2012 ◽  
Vol 8 (S288) ◽  
pp. 300-301 ◽  
Author(s):  
E. Aristidi ◽  
A. Agabi ◽  
E. Fossat ◽  
A. Ziad ◽  
L. Abe ◽  
...  
Keyword(s):  
Strong Dependence ◽  
Ground Level ◽  
Bright Star ◽  
Optical Turbulence ◽  
Outer Scale ◽  
Site Testing ◽  
Visible Wavelength ◽  
Integrated Optical ◽  
Turbulence Parameters

AbstractWe present long term site testing statistics based on DIMM and GSM data obtained at Dome C, Antarctica. These data have been collected on the bright star Canopus since the end of 2003. We give values of the integrated turbulence parameters in the visible (wavelength 500 nm). The median value we obtained for the seeing are 1.2 arcsec, 2.0 arcsec and 0.8 arcsec at respective elevations of 8m, 3m and 20m above the ground. The isoplanatic angle median value is 4.0 arcsec and the median outer scale is 7.5m. We found that both the seeing and the isoplanatic angle exhibit a strong dependence with the season (the seeing is larger in winter while the isoplanatic angle is smaller).

scholarly journals Strong Wind Characteristics and Buffeting Response of a Cable-Stayed Bridge under Construction

Sensors ◽  
2020 ◽  
Vol 20 (4) ◽  
pp. 1228 ◽  
Author(s):  
Lei Yan ◽  
Lei Ren ◽  
Xuhui He ◽  
Siying Lu ◽  
Hui Guo ◽  
...  
Keyword(s):  
Field Measurements ◽  
Element Model ◽  
Vertical Acceleration ◽  
Strong Wind ◽  
Buffeting Response ◽  
Cable Stayed Bridge ◽  
Wind Characteristics ◽  
Strong Winds ◽  
Under Construction ◽  
Turbulence Parameters

This study carries out a detailed full-scale investigation on the strong wind characteristics at a cable-stayed bridge site and associated buffeting response of the bridge structure during construction, using a field monitoring system. It is found that the wind turbulence parameters during the typhoon and monsoon conditions share a considerable amount of similarity, and they can be described as the input turbulence parameters for the current wind-induced vibration theory. While the longitudinal turbulence integral scales are consistent with those in regional structural codes, the turbulence intensities and gust factors are less than the recommended values. The wind spectra obtained via the field measurements can be well approximated by the von Karman spectra. For the buffeting response of the bridge under strong winds, its vertical acceleration responses at the extreme single-cantilever state are significantly larger than those in the horizontal direction and the increasing tendencies with mean wind velocities are also different from each other. The identified frequencies of the bridge are utilized to validate its finite element model (FEM), and these field-measurement acceleration results are compared with those from the FEM-based numerical buffeting analysis with measured turbulence parameters.

Therapy and prevention for mental health: What if mental diseases are mostly not brain disorders?

2019 ◽  
Vol 42 ◽  
Author(s):  
John P. A. Ioannidis
Keyword(s):  
Mental Health ◽  
Mental Disease ◽  
Brain Disorders ◽  
Social Stressors ◽  
Labor Education ◽  
Mental Diseases ◽  
Long Term Follow Up ◽  
Political Decisions

AbstractNeurobiology-based interventions for mental diseases and searches for useful biomarkers of treatment response have largely failed. Clinical trials should assess interventions related to environmental and social stressors, with long-term follow-up; social rather than biological endpoints; personalized outcomes; and suitable cluster, adaptive, and n-of-1 designs. Labor, education, financial, and other social/political decisions should be evaluated for their impacts on mental disease.

Conceptual short-term memory (CSTM) supports core claims of Christiansen and Chater

2016 ◽  
Vol 39 ◽  
Author(s):  
Mary C. Potter
Keyword(s):  
Working Memory ◽  
Rapid Serial Visual Presentation ◽  
Language Comprehension ◽  
Short Term Memory ◽  
Visual Presentation ◽  
Long Term Memory ◽  
Short Term ◽  
Term Memory ◽  
Use Of Knowledge

AbstractRapid serial visual presentation (RSVP) of words or pictured scenes provides evidence for a large-capacity conceptual short-term memory (CSTM) that momentarily provides rich associated material from long-term memory, permitting rapid chunking (Potter 1993; 2009; 2012). In perception of scenes as well as language comprehension, we make use of knowledge that briefly exceeds the supposed limits of working memory.

Brief summary of Kleť photographic search programme for minor planets

1999 ◽  
Vol 173 ◽  
pp. 189-192
Author(s):  
J. Tichá ◽  
M. Tichý ◽  
Z. Moravec
Keyword(s):  
Ccd Camera ◽  
Minor Planet ◽  
Minor Planets ◽  
Main Belt

AbstractA long-term photographic search programme for minor planets was begun at the Kleť Observatory at the end of seventies using a 0.63-m Maksutov telescope, but with insufficient respect for long-arc follow-up astrometry. More than two thousand provisional designations were given to new Kleť discoveries. Since 1993 targeted follow-up astrometry of Kleť candidates has been performed with a 0.57-m reflector equipped with a CCD camera, and reliable orbits for many previous Kleť discoveries have been determined. The photographic programme results in more than 350 numbered minor planets credited to Kleť, one of the world's most prolific discovery sites. Nearly 50 per cent of them were numbered as a consequence of CCD follow-up observations since 1994.This brief summary describes the results of this Kleť photographic minor planet survey between 1977 and 1996. The majority of the Kleť photographic discoveries are main belt asteroids, but two Amor type asteroids and one Trojan have been found.

Evolution of Large-Scale Coronal Structures

1994 ◽  
Vol 144 ◽  
pp. 29-33
Author(s):  
P. Ambrož
Keyword(s):  
Magnetic Field ◽  
Field Line ◽  
Large Scale ◽  
Coronal Magnetic Field ◽  
Source Surface ◽  
Solar Cycles ◽  
Characteristic Relationship ◽  
The Magnetic Field ◽  
Coronal Structures

AbstractThe large-scale coronal structures observed during the sporadically visible solar eclipses were compared with the numerically extrapolated field-line structures of coronal magnetic field. A characteristic relationship between the observed structures of coronal plasma and the magnetic field line configurations was determined. The long-term evolution of large scale coronal structures inferred from photospheric magnetic observations in the course of 11- and 22-year solar cycles is described.Some known parameters, such as the source surface radius, or coronal rotation rate are discussed and actually interpreted. A relation between the large-scale photospheric magnetic field evolution and the coronal structure rearrangement is demonstrated.

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