Numerical treatment of seismic accelerograms and of inelastic seismic structural responses using harmonic wavelets

The harmonic wavelet transform is employed to analyze various kinds of nonstationary signals common in aseismic design. The effectiveness of the harmonic wavelets for capturing the temporal evolution of the frequency content of strong ground motions is demonstrated. In this regard, a detailed study of important earthquake accelerograms is undertaken and smooth joint time-frequency spectra are provided for two near-field and two far-field records; inherent in this analysis is the concept of the mean instantaneous frequency. Furthermore, as a paradigm of usefulness for aseismic structural purposes, a similar analysis is conducted for the response of a 20-story steel frame benchmark building considering one of the four accelerograms scaled by appropriate factors as the excitation to simulate undamaged and severely damaged conditions for the structure. The resulting joint time-frequency representation of the response time histories captures the influence of nonlinearity on the variation of the effective natural frequencies of a structural system during the evolution of a seismic event. In this context, the potential of the harmonic wavelet transform as a detection tool for global structural damage is explored in conjunction with the concept of monitoring the mean instantaneous frequency of records of critical structural responses

Building a Better Pedestrian and Bicycling Infrastructure

The Federal Highway Administration has a long history of supporting pedestrian and bicycle transportation through funding, policy guidance, program management, and resource development. This Strategic Agenda for Pedestrian and Bicycle Transportation builds on this support and sets the stage for our activities in the coming years

Oxygen producing microscale spheres affect cell survival in conditions of oxygen-glucose deprivation in a cell specific manner: implications for cell transplantation

This study outlines the synthesis of microscale oxygen producing spheres, which, when used in conjunction with catalase, can raise the dissolved oxygen content of cell culture media for 16–20 hours. In conditions of oxygen and glucose deprivation, designed to mimic the graft environment in vivo, the spheres rescue SH-SY5Y cells and meschymal stem cells, showing that oxygen producing biomaterials may hold potential to improve the survival of cells post-transplantation

Oxygen producing microscale spheres affect cell survival in conditions of oxygen-glucose deprivation in a cell specific manner: Implications for cell transplantation

This study outlines the synthesis of microscale oxygen producing spheres, which, when used in conjunction with catalase, can raise the dissolved oxygen content of cell culture media for 16-20 hours. In conditions of oxygen and glucose deprivation, designed to mimic the graft environment in vivo, the spheres rescue SH-SY5Y cells and meschymal stem cells, showing that oxygen producing biomaterials may hold potential to improve the survival of cells post-transplantation

Southern hemispheric halon trends and global halon emissions, 1978–2011

The atmospheric records of four halons, H-1211 (CBrClF2), H-1301 (CBrF3), H-2402 (CBrF2CBrF2) and H-1202 (CBr2F2), measured from air collected at Cape Grim, Tasmania, between 1978 and 2011, are reported. Mixing ratios of H-1211, H-2402 and H-1202 began to decline in the early to mid-2000s, but those of H-1301 continue to increase up to mid-2011. These trends are compared to those reported by NOAA (National Oceanic and Atmospheric Administration) and AGAGE (Advanced Global Atmospheric Experiment). The observations suggest that the contribution of the halons to total tropospheric bromine at Cape Grim has begun to decline from a peak in 2008 of about 8.1 ppt. An extrapolation of halon mixing ratios to 2060, based on reported banks and predicted release factors, shows this decline becoming more rapid in the coming decades, with a contribution to total tropospheric bromine of about 3 ppt in 2060. Top-down global annual emissions of the halons were derived using a two-dimensional atmospheric model. The emissions of all four have decreased since peaking in the late 1980s–mid-1990s, but this decline has slowed recently, particularly for H-1301 and H-2402 which have shown no decrease in emissions over the past five years. The UEA (University of East Anglia) top-down model-derived emissions are compared to those reported using a top-down approach by NOAA and AGAGE and the bottom-up estimates of HTOC (Halons Technical Options Committee). The implications of an alternative set of steady-state atmospheric lifetimes are discussed. Using a lifetime of 14 yr or less for H-1211 to calculate top-down emissions estimates would lead to small, or even negative, estimated banks given reported production data. Finally emissions of H-1202, a product of over-bromination during the production process of H-1211, have continued despite reported production of H-1211 ceasing in 2010. This raises questions as to the source of these H-1202 emissions

An assessment of the technical and economic feasibility of the development and manufacture of light rail vehicles in Michigan. Final report

Notes: Report covers the period 6 June 1980-30 Sept 1980Michigan Transportation Research Program, Ann ArborMichigan Department of Transportation, Bureau of Urban and Public Transportation, Lansinghttp://deepblue.lib.umich.edu/bitstream/2027.42/418/2/45344.0001.001.pd

Public transportation interim selection criteria and management objectives. Final report

Michigan Department of Transportation, Bureau of Urban and Public Transportation, Lansinghttp://deepblue.lib.umich.edu/bitstream/2027.42/516/2/42750.0001.001.pd

Application of Wavelet Theory in the Analysis of Earthquake Motions Recorded During the Kocaeli Earthquake, Turkey 1999

The Marmara region of Turkey was shaken by an earthquake with a magnitude of 7.4 and epicentre in Golcuk on August 17, 1999. Structural damage of various degrees occurred in the region. In this paper the strong motion data acquired from this earthquake at various locations are closely inspected using Fourier transform and a time-frequency technique using harmonic wavelets developed at Cambridge, Newland (1993). The advantage of harmonic wavelet analysis when dealing with non-stationary signals like earthquakes is that one can plot the signal in a time-frequency space enabling the energy distribution in the signa4 to be observed. An introduction to wavelet theory will be presented along with various methods for applying this theory to earthquake acceleration signals for analysis. Conclusions are drawn based on the application of wavelet method to the Kocaeli Earthquake strong motion data. These data is analyzed for four locations with increasing distance from the epicentre. The energy of a signal can be broken into its constituents at different frequency bands and time locations via wavelet analysis, giving insight into the localised portions of the signal. The magnitude of accelerations decreases as one moves away from the epicentre. Wavelet transform allows us to see the discontinuities within the signal and zoom in for closer inspection. Using the wavelets, it was observed that in the Kocaeli earthquake ground motions, acceleration with same frequency occurred at different time instants. This could not have been observed by traditional DFFT methods

Transmission risk of COVID-19 in high school and college water polo

BACKGROUND: Concerns that athletes may be at a higher risk for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission has led to reduced participation in sports during the COVID-19 pandemic. We aimed to assess COVID-19 incidence and transmission during the spring 2021 high school and college water polo seasons across the United States. METHODS: This prospective observational study enrolled 1825 water polo athletes from 54 high schools and 36 colleges. Surveys were sent to coaches throughout the season, and survey data were collected and analyzed. RESULTS: We identified 17 COVID-19 cases among 1223 high school water polo athletes (1.4%) and 66 cases among 602 college athletes (11.0%). Of these cases, contact tracing suggested that three were water polo-associated in high school, and none were water polo-associated in college. Quarantine data suggest low transmission during water polo play as only three out of 232 (1.3%) high school athletes quarantined for a water polo-related exposure developed COVID-19. In college, none of the 54 athletes quarantined for exposure with an infected opponent contracted COVID-19. However, in both high school and college, despite the physical condition of water polo athletes, both high school (47%) and college athletes (21%) had prolonged return to play after contracting COVID-19, indicating the danger of COVID-19, even to athletes. CONCLUSIONS: While COVID-19 spread can occur during water polo play, few instances of spread occurred during the spring 2021 season, and transmission rates appear similar to those in other settings, such as school environments