The effect of ageing on the mechanical properties of the silk of the bridge spider Larinioides cornutus (Clerck, 1757)

We are grateful to “Nanofacility Piemonte”, INRIM Institute, for the FESEM microscope facility. N.M.P. is supported by the European Research Council (ERC StG Ideas 2011 BIHSNAM n. 279985, ERC PoC 2013 KNOTOUGH n. 632277, ERC PoC 2015 SILKENE nr. 693670), by the European Commission under the Graphene Flagship (WP10 “Nanocomposites”, n. 604391)

Verification of joint input-state estimation for force identification by means of in situ measurements on a footbridge

© © 2016 Elsevier Ltd. All rights reserved. This paper presents a verification of a joint input-state estimation algorithm using data obtained from in situ experiments on a footbridge. The estimation of the input and the system states is performed in a minimum-variance unbiased way, based on a limited number of response measurements and a system model. A dynamic model of the footbridge is obtained using a detailed finite element model that is updated using a set of experimental modal characteristics. The joint input-state estimation algorithm is used for the identification of two impact, harmonic, and swept sine forces applied to the bridge deck. In addition to these forces, unknown stochastic forces, such as wind loads, are acting on the structure. These forces, as well as measurement errors, give rise to uncertainty in the estimated forces and system states. Quantification of the uncertainty requires determination of the power spectral density of the unknown stochastic excitation, which is identified from the structural response under ambient loading. The verification involves comparing the estimated forces with the actual, measured forces. Although a good overall agreement is obtained between the estimated and measured forces, modeling errors prohibit a proper distinction between multiple forces applied to the structure for the case of harmonic and swept sine excitation.publisher: Elsevier articletitle: Verification of joint input-state estimation for force identification by means of in situ measurements on a footbridge journaltitle: Mechanical Systems and Signal Processing articlelink: http://dx.doi.org/10.1016/j.ymssp.2015.12.017 content_type: article copyright: Copyright © 2016 Elsevier Ltd. All rights reserved.status: publishe

Identification of multiple localized forces on a footbridge

An existing joint input-state estimation algorithm is extended for applications in structural dynamics. The estimation of the input and the system states is performed in a minimum-variance unbiased way, based on a limited number of response measurements and a system model. An additional method is proposed to identify the noise statistics, which are needed for the joint input-state estimation procedure and which can be used to quantify the uncertainty on the estimated forces and system states. The proposed methodology is illustrated using data from an in situ experiment on a footbridge.Hydraulic EngineeringCivil Engineering and Geoscience

Verification of Joint Input-State Estimation by In Situ Measurements on a Footbridge

An existing joint input-state estimation algorithm is extended for applications instructural dynamics. The estimation of the input and the system states is performed in a minimum-variance unbiased way, based on a limited number of responsemeasurements and a system model. The noise statistics are estimated, as they areessential for the joint input-state estimation and can be used to quantify the uncertainty on the estimated forces and system states. The methodology is illustrated using data from an in situ experiment on a footbridge.Offshore Engineerin

Verification of joint input-state estimation by means of a full scale experiment on a footbridge

This paper presents a verification of a state-of-the-art joint input-state estimation algorithm using data obtained from in situ experiments on a footbridge. A dynamic model of the footbridge is based on a detailed finite element model that is calibrated using a set of experimental modal characteristics. The joint input-state estimation algorithm is used for the identification of two impact, harmonic, and swept sine forces applied to the bridge deck. In addition to these forces, unknown stochastic forces, such as wind loads, are acting on the structure. These forces, as well as measurement errors, give rise to uncertainty in the estimated forces and system states. Quantification of the uncertainty requires determination of the power spectral density of the unknown stochastic excitation, which is identified from the structural response under ambient loading. The verification involves comparing the estimated forces with the actual, measured forces. Although a good overall agreement is obtained between the estimated and measured forces, modeling errors prohibit a proper distinction between multiple forces applied to the structure for the case of harmonic and swept sine excitation.Offshore Engineerin

Surveillance of antibiotic resistance in clinical isolates of streptococcus pneumoniae collected in Belgium during winter 2000-2001

A total of 314 isolates of Streptococcus pneumoniae collected by 10 different laboratories were tested for their susceptibility by using a microdilution technique following NCCLS recommendations. The following antibiotics were included: penicillin, ampicillin, amoxicillin, amoxicillin/clavulanate, cefaclor, cefuroxime, cefotaxime, imipenem, ciprofloxacin, gemifloxacin, levofloxacin, erythromycin, clarithromycin, azithromycin, miocamycin, clindamycin and tetracycline. The insusceptibility rate (IR) to penicillin was 21.0% [10.8% intermediate (greater than or equal to0.12-1 mug/mL) and 10.2 % high-level (greater than or equal to2 mug/mL)], to cefotaxime 7.3 % [3.5 % intermediate (greater than or equal to 1 mug/mL) and 3.8 % high-level (greater than or equal to2 mug/mL)], to imipenem 3.8 % [3.8 % intermediate (greater than or equal to0.25-0.5 mug/mL) and 0 % high-level (greater than or equal to1 mug/mL)], to ciprofloxacin 11.2 % [8.3 % intermediate (2 mug/mL) and 3.9 % high-level (greater than or equal to4 mug/mL)], to erythromycin 30.3 % [3.5 % intermediate (0.5 mug/mL) and 26.8 % high-level (greater than or equal to1 mug/mL)] and to tetracycline 38.5 % [0.9 % intermediate (4 mug/mL) and 37.6 % high-level (greater than or equal to8 mug/mL)]. No decreased susceptibility was found for gemifloxacin (greater than or equal to0.5 mug/mL). This compound was the most active with MIC50, MIC90 and an IR of 0.015 mug/mL, 0.03 mug/mL, and 0 % respectively, followed by amoxicillin/ clavulanate, amoxicillin and imipenem (MIC50, MIC90 and IR: 0.015 mug/mL, 1 mug/mL, 1.6 %/ 0.015 mug/mL, 1 mug/mL, 1.9 %/ 0.008 mug/mL, 0.12 mug/mL, 3.8 % respectively). Compared to the 1999 surveillance, penicillin and tetracycline-insusceptibility increased with 4.9 % and 15.6% respectively, while cefotaxime, erythromycin and ciprofloxacin insusceptibility decreased with 5.4 %, 5.8 % and 4.4 % respectively. MICs of all beta-lactams rose with those of penicillin for penicillin-insusceptible isolates. Imipenem, cefotaxime, amoxicillin and amoxicillin/clavulanate were generally 4, 2, 1 and 1 doubling dilutions respectively more potent than penicillin on these isolates while ampicillin, cefuroxime and cefaclor were generally 1, 2 and 4 dilutions respectively less potent. Most penicillin-insusceptible isolates remained fully susceptible to amoxicillin/clavulanate (92.4 %), amoxicillin (90.9 %) and imipenem (81.8 %). Erythromycin-tetracycline insusceptibility was the most common resistance phenotype (14.3 %). Three- and four-fold resistance was found in 12.4 % and 1.6 % respectively of the isolates. Most penicillin-insusceptible isolates were of capsular types 14 (22.7 %), 23 (21.2 %), 6 (18.2 %), 9 (13.6 %) and 19 (12.1 %)