Wavelet-based evolutionary response of multi-span structures including wave-passage and site-response effects

Stochastic seismic wavelet-based evolutionary response of multispan structures including wave-passage and site-response effects is formulated in this paper. A procedure to estimate site-compatible parameters of surface-to-bedrock frequency response function (FRF) by using finite-element analysis of the supporting soil medium is proposed. The earthquake energy content is represented by a composite power spectrum density function contributed by the surface-to-bedrock FRF and bedrock power spectra. A long span multisupport structure is subjected to spatially varying differential support motions where the spatial-variability is represented by bedrock parametric coherency models and time-lags. In addition to the time-lags from wave-passage effects, the site-response effects from different soil conditions at the supports are characterized by frequency-dependent time-lags. In an illustrative case study, a three-span, two-dimensional hangar frame is analyzed using the proposed formulations. The time-lags resulting from site-response effects and computed by different FRFs show different variation in trends and frequency content. The site-response effect is found to introduce additional frequency nonstationarity and leads to an increase in the frame responses but with slower attenuation in time.Geoscience & EngineeringCivil Engineering and Geoscience

L'Impact écologique des activités économiques en mer de Chine méridionale

[Extract] La mer de Chine méridionale est une large région marine qui s'étend sur une aire de plus de trois millions de kilomètres carrés, limitée par les côtes de dix pays asiatiques et contient plusieurs petites îles. Les enjeux économiques, stratégiques et écologiques dans cette région sont nombreux (Figure 1). La région se trouve aussi sur l'une des plus importantes routes maritimes du monde. Deux tiers du trafic mondial de conteneurs et la moitié des flux d'hydrocarbures et de gaz naturel liquéfie transitent par cette zone. Plus de la moitié des vingt premiers ports mondiaux pour le traitement des conteneurs sont situés sur le pourtour de cette région. D'ailleurs, le passage par la mer de Chine méridionale est le chemin le plus court entre le Pacifique Nord et l'océan Indien. De plus, les activités économiques en mer de Chine méridionale – la construction d'Iles artificielles et la production de pétrole et de gaz naturel – suscitent des tensions dans la zone comme les contributions précédentes I ‘ont démontré. Et pourtant, la mer de Chine méridionale recelé une biodiversité extraordinaire. Une étude en 2015 analysant les données de 16 zones récifales qui s’étendent sur tout cet espace maritime a montré qu'il contenait 571 espèces de coraux, et qu'il était aussi riche que la zone voisine, le Triangle de Corail, considérée par !'organisation WWF (Fonds mondial pour la nature) com me prioritaire pour la conservation marine. Malheureusement, l'accès a cette région étant rendu impossible par la Chine, les études d'impact sont peu nombreuses et difficiles à actualiser

Active contact tracing beyond the household in multidrug resistant tuberculosis in Vietnam: a cohort study

Contains fulltext : 202911.pdf (publisher's version ) (Open Access)BACKGROUND: Currently in Vietnam contact tracing for multidrug-resistant tuberculosis (MDR-TB) entails passive case finding among symptomatic household contacts who present themselves for diagnosis. Close contacts of MDR-TB cases are therefore not identified adequately. We assessed the added value of active contact tracing within and beyond households using social network questionnaires to identify close contacts of MDR-TB patients in Vietnam. METHODS: We conducted a cohort study using social network questionnaires in which contacts were identified by MDR-TB patients, including contacts from 'high risk' places like work. Contacts of MDR-TB patients were followed up and screened over a period of at least 6 months. This included two active screenings and any unscheduled passive screening of self-referred contacts during the study period. RESULTS: Four hundred seventeen contacts of 99 index cases were recruited, 325 (77.9%) and 160/417 (38.4%) contacts participated in the first and second screenings, respectively. The first screening detected one TB case but the bacteria were not MDR. From passive screening, a household contact was diagnosed with TB meningitis but not through our active approach. Social network analysis showed that only 1/17 (5.9%) high-risk places agreed to cooperate and were included in the screening, and no MDR-TB cases were detected. There were two pairs of index cases (identified separately) who were found to be contacts of each other and who had been diagnosed before the study started. CONCLUSIONS: No new MDR-TB cases were detected using social network analysis of nearly 100 MDR-TB index cases, likely due to a relatively short follow up time, and loss to follow up (lack of cooperation from contacts or high risk places and lack of available resources in the National Tuberculosis Control Programme)

PISA:: Recent developments in offshore wind turbine monopile design

This paper provides a brief overview of the Pile Soil Analysis (PISA) project, recently completed in the UK. The research was aimed at developing new design methods for laterally loaded monopile foundations, such as those supporting offshore wind turbine structures. The paper first describes the background to the project and briefly outlines the key research elements completed. The paper concludes with a brief description of the anticipated impact of the work and describes initiatives that have followed since