989 research outputs found
Structural vulnerability of Nepalese Pagoda temples
Nepal is located in one of the most severe earthquake prone areas of the world, lying between collisions of Indian to the Eurasian plate, moving continuously, resulting in frequent devastating earthquakes within this region. Moreover, different authors refer mention that the accumulated slip deficit (central seismic gap) is likely to produce large earthquakes in the future. Also, the analysis of the available information of previous earthquakes indicates the potential damage that can occurs in unreinforced traditional masonry structures in future earthquakes.
Most of the Nepalese pagoda temples were erected following very simple rules and construction details to accomplish with seismic resistance requirement, or even without any consideration for seismic resistance, during the period of Malla dynasty (1200-1768). Presently, conservation and restoration of ancient monuments are one of the major concerns in order to preserve our built heritage, transferring it to the future generations. The present paper is devoted to outline particular structural fragility characteristics in the historic Nepalese pagoda temples which affect their seismic performance. Moreover, based on the parametric analysis identified structural weaknesses/fragilities of pagoda topology, the associated traditional building technology and constructional details
Probable or Improbable Universe? Correlating Electroweak Vacuum Instability with the Scale of Inflation
Measurements of the Higgs boson and top quark masses indicate that the
Standard Model Higgs potential becomes unstable around
GeV. This instability is cosmologically relevant since quantum fluctuations
during inflation can easily destabilize the electroweak vacuum if the Hubble
parameter during inflation is larger than (as preferred by the
recent BICEP2 measurement). We perform a careful study of the evolution of the
Higgs field during inflation, obtaining different results from those currently
in the literature. We consider both tunneling via a Coleman-de Luccia or
Hawking-Moss instanton, valid when the scale of inflation is below the
instability scale, as well as a statistical treatment via the Fokker-Planck
equation appropriate in the opposite regime. We show that a better
understanding of the post-inflation evolution of the unstable AdS vacuum
regions is crucial for determining the eventual fate of the universe. If these
AdS regions devour all of space, a universe like ours is indeed extremely
unlikely without new physics to stabilize the Higgs potential; however, if
these regions crunch, our universe survives, but inflation must last a few
e-folds longer to compensate for the lost AdS regions. Lastly, we examine the
effects of generic Planck-suppressed corrections to the Higgs potential, which
can be sufficient to stabilize the electroweak vacuum during inflation.Comment: 26 pages, 7 figures. Clarifications added. Matches published version
in JHE
Condition Factor Calibration for Load and Resistance Factor Rating of Steel Girder Bridges
The Load and Resistance Factor Rating (LRFR) is a reliability-based rating procedure complementary to the Load and Resistance Factor Design (LRFD). The intent of LRFR is to provide consistent reliability for all bridges regardless of in-situ condition. The primary difference between design and rating is the uncertain severity and location of deterioration, including the potential future loss of strength for an element already evidencing deterioration. Ostensibly, these uncertainties are accounted for by applying an additional strength reduction factor: the condition factor, Ï•c. Currently, condition factors are nominally correlated to the condition of the member, which can be Good, Fair, or Poor. However, definitions of these condition categories are deferred to inspection documents, which themselves lack clear, objective definitions. Furthermore, lack of guidance to account for the location and extent of deterioration exacerbates confusion in the methodology to appropriately assign condition factors. These ambiguities cause incoherence between inspection and rating processes by introducing additional uncertainty. The additional uncertainty skews load ratings, sometimes producing ratings with unintended conservativism, and sometimes overestimating the safe load-carrying capacity of a bridge. This study presents a calibration of Ï•c to be used with steel girder bridges, accounting for uncertainty due to non-uniform deterioration throughout transverse sections, lack of knowledge of the longitudinal location(s) of the deterioration, and the likelihood of further deterioration over the next inspection cycle for ranges of section loss for each condition. Section loss rangers are proposed to define each condition state for potential implementation by inspectors. The proposed condition state definitions and implementation methodology can improve uniformity in the inspection process and produce bridge load ratings that are more consistent with the target reliability intended by the rating procedure.
Advisor: Joshua Steelma
Condition Factor Calibration for Load and Resistance Factor Rating of Steel Girder Bridges
The Load and Resistance Factor Rating (LRFR) is a reliability-based rating procedure complementary to the Load and Resistance Factor Design (LRFD). The intent of LRFR is to provide consistent reliability for all bridges regardless of in-situ condition. The primary difference between design and rating is the uncertain severity and location of deterioration, including the potential future loss of strength for an element already evidencing deterioration. Ostensibly, these uncertainties are accounted for by applying an additional strength reduction factor: the condition factor, Ï•c. Currently, condition factors are nominally correlated to the condition of the member, which can be Good, Fair, or Poor. However, definitions of these condition categories are deferred to inspection documents, which themselves lack clear, objective definitions. Furthermore, lack of guidance to account for the location and extent of deterioration exacerbates confusion in the methodology to appropriately assign condition factors. These ambiguities cause incoherence between inspection and rating processes by introducing additional uncertainty. The additional uncertainty skews load ratings, sometimes producing ratings with unintended conservativism, and sometimes overestimating the safe load-carrying capacity of a bridge. This study presents a calibration of Ï•c to be used with steel girder bridges, accounting for uncertainty due to non-uniform deterioration throughout transverse sections, lack of knowledge of the longitudinal location(s) of the deterioration, and the likelihood of further deterioration over the next inspection cycle for ranges of section loss for each condition. Section loss rangers are proposed to define each condition state for potential implementation by inspectors. The proposed condition state definitions and implementation methodology can improve uniformity in the inspection process and produce bridge load ratings that are more consistent with the target reliability intended by the rating procedure.
Advisor: Joshua Steelma
Spacetime Dynamics of a Higgs Vacuum Instability During Inflation
A remarkable prediction of the Standard Model is that, in the absence of
corrections lifting the energy density, the Higgs potential becomes negative at
large field values. If the Higgs field samples this part of the potential
during inflation, the negative energy density may locally destabilize the
spacetime. We use numerical simulations of the Einstein equations to study the
evolution of inflation-induced Higgs fluctuations as they grow towards the true
(negative-energy) minimum. These simulations show that forming a single patch
of true vacuum in our past light cone during inflation is incompatible with the
existence of our Universe; the boundary of the true vacuum region grows outward
in a causally disconnected manner from the crunching interior, which forms a
black hole. We also find that these black hole horizons may be arbitrarily
elongated---even forming black strings---in violation of the hoop conjecture.
By extending the numerical solution of the Fokker-Planck equation to the
exponentially suppressed tails of the field distribution at large field values,
we derive a rigorous correlation between a future measurement of the
tensor-to-scalar ratio and the scale at which the Higgs potential must receive
stabilizing corrections in order for the Universe to have survived inflation
until today.Comment: 36 pages, 11 figures; revised to match published versio
Condition Factor Calibration for Load and Resistance Factor Rating of Steel Girder Bridges
Load and Resistance Factor Rating (LRFR) is a reliability-based rating procedure complementary to Load and Resistance Factor Design (LRFD). The intent of LRFR is to provide consistent reliability for all bridges regardless of in-situ condition. The primary difference between design and rating is the uncertain severity and location of deterioration, including the potential future loss of strength for an element already evidencing deterioration. Ostensibly, these uncertainties are addressed by applying an additional strength reduction factor: the condition factor, Ï•c. Currently, condition factors are nominally correlated to the condition of the member, which can be Good, Fair, or Poor. However, definitions of these condition categories are deferred to inspection documents, which themselves lack clear, objective definitions. Furthermore, lack of guidance to account for the location and extent of deterioration exacerbates confusion in the methodology to appropriately assign condition factors. These ambiguities cause incoherence between inspection and rating processes by introducing additional uncertainty. The additional uncertainty skews load ratings, sometimes producing ratings with unintended conservativism, and sometimes overestimating the safe load-carrying capacity of a bridge. This study presents a calibration of Ï•c to be used with steel girder bridges, accounting for uncertainty due to non-uniform deterioration throughout transverse sections, unquantified severity of section loss associated with condition states, lack of knowledge of the longitudinal location(s) of the deterioration, and the likelihood of further deterioration over the next inspection cycle for ranges of section loss for each condition. The proposed condition state definitions and implementation methodology are intended to improve uniformity in the inspection process and produce bridge load ratings that are more consistent with the target reliability intended by the LRFR rating procedure
The magnetic field effect on the transport and efficiency of group III tris(8-hydroxyquinoline) organic light emitting diodes
Copyright 2008 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. This article appeared in Journal of Applied Physics 103, 103715 (2008) and may be found at
Recommended from our members
Roadside Exposure and Inflammation Biomarkers among a Cohort of Traffic Police in Kathmandu, Nepal
Air pollution is a major environmental problem in the Kathmandu Valley. Specifically, roadside and traffic-related air pollution exposure levels were found at very high levels exceeding Nepal air quality standards for daily PM2.5. In an exposure study involving traffic police officers, we collected 78 blood samples in a highly polluted spring season (16 February 2014–4 April 2014) and 63 blood samples in the less polluted summer season (20 July 2014–22 August 2014). Fourteen biomarkers, i.e., C-reactive protein (CRP), serum amyloid A (SAA), intracellular adhesion molecule (ICAM-1), vascular cell adhesion molecule (VCAM-1), interferon gamma (IFN-γ), interleukins (IL1-β, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12, IL-13), and tumor necrosis factor (TNF-α) were analyzed in collected blood samples using proinflammatory panel 1 kits and vascular injury panel 2 kits. All the inflammatory biomarker levels were higher in the summer season than in the spring season, while particulate levels were higher in the spring season than in the summer season. We did not find significant association between 24-hour average PM2.5 or black carbon (BC) exposure levels with most of analyzed biomarkers for the traffic volunteers working and residing near busy roads in Kathmandu, Nepal, during 2014. Inflammation and vascular injury marker concentrations were generally higher in females, suggesting the important role of gender in inflammation biomarkers. Because of the small sample size of female subjects, further investigation with a larger sample size is required to confirm the role of gender in inflammation biomarkers
- …