Bridge Digital Twining Using an Output-Only Bayesian Model Updating Method and Recorded Seismic Measurements

Rapid post-earthquake damage diagnosis of bridges can guide decision-making for emergency response management and recovery. This can be facilitated using digital technologies to remove the barriers of manual post-event inspections. Prior mechanics-based Finite Element (FE) models can be used for post-event response simulation using the measured ground motions at nearby stations; however, the damage assessment outcomes would suffer from uncertainties in structural and soil material properties, input excitations, etc. For instrumented bridges, these uncertainties can be reduced by integrating sensory data with prior models through a model updating approach. This study presents a sequential Bayesian model updating technique, through which a linear/nonlinear FE model, including soil-structure interaction effects, and the foundation input motions are jointly identified from measured acceleration responses. The efficacy of the presented model updating technique is first examined through a numerical verification study. Then, seismic data recorded from the San Rogue Canyon Bridge in California are used for a real-world case study. Comparison between the free-field and the foundation input motions reveals valuable information regarding the soil-structure interaction effects at the bridge site. Moreover, the reasonable agreement between the recorded and estimated bridge responses shows the potentials of the presented model updating technique for real-world applications. The updated FE model is considered as the digital twin of the bridge and can be used to analyze the bridge and monitor the structural response at element, section, and fiber levels to diagnose the location and severity of any potential damage mechanism.

Effect of Base Conditions in One-Dimensional Numerical Simulation of Seismic Site Response: A Technical Note for Best Practice

The effects induced by the choice of numerical base conditions for evaluating local seismic response are investigated in this technical note, aiming to provide guidelines for professional applications. A numerical modelling of the seismic site response is presented, assuming a one-dimensional scheme. At first, with reference to the case of a homogeneous soil layer overlying a half-space, two different types of numerical base conditions, named rigid and elastic, were adopted to analyse the seismic site response. Then, geological setting, physical and mechanical properties were selected from Italian case studies. In detail, the following stratigraphic successions were considered: shallow layer 1 (shear wave velocity, VS, equal to 400 m/s), layer 2 (VS equal to 600 m/s) and layer 3 (VS equal to 800 m/s). In addition, real signals were retrieved from the web site of the Italian accelerometric strong motion network. Rigid and elastic base conditions were adopted to estimate the ground motion modifications of the reference signals. The results are presented in terms of amplification factors (i.e., ratio of integral quantities referred to free-field and reference response spectra) and are compared between the adopted numerical models.

The Bonebridge BCI 602 Active Transcutaneous Bone Conduction Implant in Children: Objective and Subjective Benefits

Background: the Bonebridge hearing implant is an active transcutaneous bone conduction implant suitable for various types of hearing loss. It was first launched in 2012 as the BCI 601, with a newer internal part (BCI 602) released in 2019. With the new size and shape, the BCI 602 can be used in patients previously excluded due to insufficient anatomical conditions, especially in patients with congenital defects of the outer and middle ear. Objectives: the purpose of this study is to evaluate the objective and subjective benefits of the new Bonebridge BCI 602 in children who have hearing impairment due to conductive or mixed hearing loss. Safety and effectiveness of the device was assessed. Methods: the study group included 22 children aged 8–18 years (mean age 14.7 years) who had either conductive or mixed hearing loss. All patients were implanted unilaterally with the new Bonebridge BCI 602 implant. Pure tone audiometry, speech recognition tests (in quiet and noise), and free-field audiometry were performed before and after implantation. Word recognition scores were evaluated using the Demenko and Pruszewicz Polish Monosyllabic Word Test, and speech reception thresholds in noise were assessed using the Polish Sentence Matrix Test. The subjective assessment of benefits was carried outusing the APHAB (Abbreviated Profile of Hearing Aid Benefit) questionnaire. Results: after implantation of the Bonebridge BCI 602 all patients showed a statistically significant improvement in hearing and speech understanding. The mean word recognition score (WRS) changed from 12.1% before implantation to 87.3% after 6 months. Mean speech reception threshold (SRT) before implantation was +4.79 dB SNR and improved to −1.29 dB SNR after 6 months. All patients showed stable postoperative results. The APHAB questionnaire showed that difficulties in hearing decreased after implantation, with a statistically significant improvement in global score. Pre-operative scores (M = 35.7) were significantly worse than post-operative scores at 6 months (M = 25.7). Conclusions: the present study confirms that the Bonebridge BCI 602 is an innovative and effective solution, especially for patients with conductive and mixed hearing loss due to anatomical ear defects. The Bonebridge BCI 602 system provides valuable and stable audiological and surgical benefits. Subjective assessment also confirms the effectiveness of the BCI 602. The BCI 602 offers the same amplification as the BCI601, but with a smaller size. The smaller dimensions make it an effective treatment option for a wider group of patients, especially children with congenital defects of the outer and middle ear.

Development of a Personal Ultrasound Exposimeter for Occupational Health Monitoring

Prolonged exposure to airborne ultrasound in a workplace can have a detrimental influence on a worker’s well-being. Given the ever-increasing use of ultrasonic industrial equipment, it is of vital importance—and may also be regulated by law—to monitor ultrasound exposure during a normal workday as part of workplace risk assessment. However, the devices currently utilized exhibit limitations with regard to both their operational frequency and their portability (wearability). In this paper, the first prototype of a high-frequency and ultrasound personal exposimeter is presented in the light of the latest national and international standards governing high-frequency and ultrasonic noise measurement in the field of occupational health monitoring. The prototype was tested in the laboratory environment in order to assess its sound level detection capabilities in both the audible and ultrasonic frequency ranges. Several common industrial scenarios—including an ultrasonic welding machine, an ultrasonic cleaning bath, and a compressed air gun—were simulated in a laboratory environment. For each simulated set-up, a corresponding high-frequency or ultrasonic signal was fed through a specially prepared generation chain. Each experimental scenario was initially surveyed with an ultrasound level meter previously tested up to 100 kHz. This was followed by a measurement with the prototype. For this study, the simulated sound signals varied between 10 kHz and 40 kHz on the frequency scale and between 60 dB and 90 dB in amplitude. The portability of the prototype, which may be required to be worn throughout an entire workday (e.g., 8 h), was also considered. All the experiments were performed on a customized ultrasound measurement set-up within a free-field environment located at the Physikalisch-Technische Bundesanstalt (PTB) in Braunschweig, Germany. Results obtained suggest a good agreement between the measurements performed with both devices in the louder areas of the sound fields produced. Because the overall measurement uncertainty is highly dependent on the specificity of the individual measurement set-up and measurement procedure, an uncertainty budget estimated for the prototype considers electro-acoustical contributions only.

Cluster capacity functionals and isomorphism theorems for Gaussian free fields

We investigate level sets of the Gaussian free field on continuous transient metric graphs $$\widetilde{{\mathcal {G}}}$$ G ~ and study the capacity of its level set clusters. We prove, without any further assumption on the base graph $${\mathcal {G}}$$ G , that the capacity of sign clusters on $$\widetilde{{\mathcal {G}}}$$ G ~ is finite almost surely. This leads to a new and effective criterion to determine whether the sign clusters of the free field on $$\widetilde{{\mathcal {G}}}$$ G ~ are bounded or not. It also elucidates why the critical parameter for percolation of level sets on $$\widetilde{{\mathcal {G}}}$$ G ~ vanishes in most instances in the massless case and establishes the continuity of this phase transition in a wide range of cases, including all vertex-transitive graphs. When the sign clusters on $$\widetilde{{\mathcal {G}}}$$ G ~ do not percolate, we further determine by means of isomorphism theory the exact law of the capacity of compact clusters at any height. Specifically, we derive this law from an extension of Sznitman’s refinement of Lupu’s recent isomorphism theorem relating the free field and random interlacements, proved along the way, and which holds under the sole assumption that sign clusters on $$\widetilde{{\mathcal {G}}}$$ G ~ are bounded. Finally, we show that the law of the cluster capacity functionals obtained in this way actually characterizes the isomorphism theorem, i.e. the two are equivalent.

Pre-service physics teachers’ mental models about the electric field

This paper identifies pre-service physics teachers’ mental models of the concept of the electric field. The models were determined by means of five contexts all of which were supported with sets of experiments. The contexts examined were (1) the effect of the electric field on the insulator, (2) the comparison of the conductor and insulator in the electric field, (3) the effect of the electric field on the neutral conductor and insulator, (4) the effect of the electric field on the conductor liquid, and (5) the effect of the conductor and insulators materials forming a closed surface on the electric field. Semi-structured interviews related to the contexts were conducted with the 22 pre-service physics teachers. The data collected throughout the interviews were put to content analysis and thus, the pre-service teachers’ mental models were identified. In total, six mental models were identified. One model was a scientific model (Scientific Model of the Electric Field (SMEF)) and five of which were unscientific models (Magnetic-Based Field Model (MBFM), Mechanical Wave Model (MWM), Material Independent Field Model (MIFM), Force-Free Field Model (FFFM) and Force-Based Field Model (FBFM)) were identified. It became apparent as a result of document analysis that several unscientific mental models were also included in resource books. Approximately one and a half years later, almost all students were interviewed again about the contexts so as to find whether or not their models were permanent or not. Following the interviews, their mental models were found to be quite permanent and to be time-independent.

Influence of Water-Structure and Soil-Structure Interaction on Seismic Performance of Sea-Crossing Continuous Girder Bridge

Based on the Hong Kong-Zhuhai-Macao project, considering the fluid-structure interaction and soil-structure interaction, the seismic response of a sea-crossing continuous girder bridge is analyzed. Three-dimensional nonlinear numerical bridge model is developed, in which the hydrodynamic force is represented by added mass and pile-soil interaction is represented by p-y elements. Meanwhile, stratification of soil is considered in the free field analysis. Through the comparison of responses of the bridge cases, the effects of earthquake-induced hydrodynamic force and pile-soil interaction are studied. For the influence of hydrodynamic force, the results show that it is relatively slight as compared with pile-soil interaction; moreover pile foundation is more sensitive to it than other bridge components. The influence of pile-soil interaction is relatively significant. When both of the interactions are considered, the influence is not a simple superposition of acting alone, so it is recommended to consider both factors in dynamic analysis.