Vibration induced damage due to construction work – Blasting tests

In this study, two instrumented blast test series were performed in a rock quarry in Norway. For the first test series, two buildings were erected, one made of Light Expanded Clay Aggregate (Leca) blocks, and one in cast-in-place unreinforced concrete. Both buildings were founded on a thin compacted gravel layer over rock. In the second test series one building made of Leca blocks was erected on top of an about 4 m thick filling, established at the same location as the buildings in the first test series. The test buildings were instrumented with triaxial geophones, accelerometers and Fiber Bragg Grating Sensors (strain sensors) in multiple positions. To gain full control, repeatability and traceability of the blasts, packaged emulsion and NG-based explosives together with electronic detonators were used

Building vibration induced by sonic boom - field test in Russia

Infrasound and audible sound at very low frequency from sources such as military aircrafts, explosions and wind mills can induce building vibration involving both rattling and whole-body vibration strong enough to cause annoyance. Sonic boom is of special interest in this context due to its very low frequency content that coincides with the most important frequency range for both building vibration and human perception. This paper presents results from field tests with measurements of noise and building vibrations from sonic booms performed at the Tretyakovo airport in Russia. Transmission loss from outdoor to indoor noise, noise induced floor vibration and whole building vibration are determined. Furthermore, the measured acoustic vibration admittance is used to estimate vibration values in the same building from low boom flight passages using synthesized sound pressure time series. Boom induced floor vibration both from the measured flight passages in Russia and from synthesized low boom time series are estimated also for a lightweight wooden building, using previously measured acoustic vibration admittances. The results clearly show perceptible levels of vibrations from sonic boom along with a great influence of the building type which indicates that there can be a big difference between the European countries depending on the building tradition. Finally, it is shown that outdoor sound levels weighted with the C-curve correlates best with frequency weighted floor vibration values.Building vibration induced by sonic boom - field test in RussiapublishedVersio

Genomic Consequences of Fragmentation in the Endangered Fennoscandian Arctic Fox (Vulpes lagopus)

Accelerating climate change is causing severe habitat fragmentation in the Arctic, threatening the persistence of many cold-adapted species. The Scandinavian arctic fox (V. lagopus) is highly fragmented, with a once continuous, circumpolar distribution, it struggled to recover from a demographic bottleneck in the late 19th century. The future persistence of the entire Scandinavian population is highly dependent on the northernmost Fennoscandian subpopulations (Scandinavia and the Kola Peninsula), to provide a link to the viable Siberian population. By analyzing 43 arctic fox genomes, we quantified genomic variation and inbreeding in these populations. Signatures of genome erosion increased from Siberia to northern Sweden indicating a stepping-stone model of connectivity. In northern Fennoscandia, runs of homozygosity (ROH) were on average ~1.47-fold longer than ROH found in Siberia, stretching almost entire scaffolds. Moreover, consistent with recent inbreeding, northern Fennoscandia harbored more homozygous deleterious mutations, whereas Siberia had more in heterozygous state. This study underlines the value of documenting genome erosion following population fragmentation to identify areas requiring conservation priority. With the increasing fragmentation and isolation of Arctic habitats due to global warming, understanding the genomic and demographic consequences is vital for maintaining evolutionary potential and preventing local extinctions. inbreeding; runs of homozygosity; bottleneck; fragmentation; mutational load; conservatio

The European Reference Genome Atlas: piloting a decentralised approach to equitable biodiversity genomics.

ABSTRACT: A global genome database of all of Earth’s species diversity could be a treasure trove of scientific discoveries. However, regardless of the major advances in genome sequencing technologies, only a tiny fraction of species have genomic information available. To contribute to a more complete planetary genomic database, scientists and institutions across the world have united under the Earth BioGenome Project (EBP), which plans to sequence and assemble high-quality reference genomes for all ∼1.5 million recognized eukaryotic species through a stepwise phased approach. As the initiative transitions into Phase II, where 150,000 species are to be sequenced in just four years, worldwide participation in the project will be fundamental to success. As the European node of the EBP, the European Reference Genome Atlas (ERGA) seeks to implement a new decentralised, accessible, equitable and inclusive model for producing high-quality reference genomes, which will inform EBP as it scales. To embark on this mission, ERGA launched a Pilot Project to establish a network across Europe to develop and test the first infrastructure of its kind for the coordinated and distributed reference genome production on 98 European eukaryotic species from sample providers across 33 European countries. Here we outline the process and challenges faced during the development of a pilot infrastructure for the production of reference genome resources, and explore the effectiveness of this approach in terms of high-quality reference genome production, considering also equity and inclusion. The outcomes and lessons learned during this pilot provide a solid foundation for ERGA while offering key learnings to other transnational and national genomic resource projects.info:eu-repo/semantics/publishedVersio

Estimation of natural frequencies and damping using dynamic field data from an offshore wind turbine

The dynamic characteristics of offshore wind turbines are heavily affected by environmental loads from wave and wind action and nonlinear soil behaviour. In the design of the monopile structures, the fatigue load due to wind and wave loading is one of the most important problems to consider. Since the fatigue damage is sensitive to the foundation stiffness and damping, increasing the accuracy of analysis tools used in the design and optimization process can improve the reliability of the structure and reduce conservatism, thereby leading to a more cost-efficient design. In this context, analysis of field data is important for calibrating and verifying purposes. This paper presents analysis of measured accelerations and strains from a wind farm in the North Sea with monopile foundations. Field data during idling conditions, collected over long periods of operation, are analysed and the natural frequencies are determined, and damping is estimated. The measured natural frequencies are compared to calculated values using an aero- servo-hydro-elastic code, showing a good agreement in the frequency range below 2 Hz. Variation of the natural frequencies with intensity of loading may indicate effect of soil nonlinearity on the overall OWT response. Since the first natural bending modes have the largest potential to mobilize soil reactions, they are of primary interest in this context. The effect of load (wave, wind and dynamic bending moment) on the first natural frequency is investigated using different analysis techniques in the frequency domain and time domain. A clear correlation between load level and first natural frequency is demonstrated. A simple nonlinear SSI model of the tower/soil system is employed to numerically investigate the observed changes in the measured first natural frequency with the level of loading and increased overall damping. The simulated results reproduce the general trends in the observed reduction in the first natural frequency and increased damping ratio with the load level. However, the effect of the load level is less than that observed in the measurements, indicating contribution also from other factors than soil nonlinearity.publishedVersio

Effect of track defects on vibration from high speed train

The response of railway tracks and trackside vibration are strongly governed by the quality of the track. Defects or non-homogeneities in the track/substructure/ground can remarkably increase the responses in the system, leading to further deterioration of the track. This issue is more dramatic in high-speed lines. The objective of this paper is to study the impact of two types of non-homogeneities on the track response. In the first case, the effect of hanging sleepers is studied, and in the second case, the effect of locally deteriorated substructure is investigated. Two numerical solutions are used for the simulation of track-substructure-ground response. The first is the frequency-domain solution VibTrain that has been developed for efficient simulation of track/ground response under moving loads using a combination of beam elements for the track/substructure and Green’s functions for the layered soil medium. The second model is a FE model in COMSOL Multiphysics enhanced with the absorbing boundary PML (Perfectly Matched Layer) in the time domain. In addition to studying the effect of track defects on rail vibration, the results of the two solutions are compared and practical conclusions are drawn on the potential of using vibration data for detection of track defects.publishedVersio