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This paper presents dynamic analyses of railway bridges traversed by heavy freight trains, with application to the iron ore line in the North of Sweden. The main objective is to show that the allowable axle load can be increased as a result of lower dynamic effects compared to current design codes, especially for short- and medium span bridges. Simulations are based on a 2D traintrack-bridge interaction model and a large set of sampled realistic track irregularities. Using a semi-probabilistic approach, the results show that for short span bridges the dynamic effects is less than 15% compared to more than 40% in current codes. For span lengths longer than 10 m the dynamic effects are less than 5% according to the simulations. A parametric study shows that the dynamic effects are proportional to the standard deviation of the track irregularities and that the main governing effects of the train is the un-sprung mass., Part of ISBN 9780784483886

One approach for upgrading existing high-speed railway bridges which are susceptible to excessive vibrations is to install damping devices. In this article, a model of a simply supported bridge with supplemental fluid viscous dampers installed between the superstructure and the abutments is derived based on an arbitrary mode of vibration. The aim is to ensure the robustness of the proposed vibration mitigation method by conducting Monte Carlo simulations including uncertainties associated with the bridge-damper system. From this statistical screening, it is possible to evaluate the probability of exceedance of a stipulated acceleration level, as well as studying the sensitivity of the ingoing random variables. This probabilistic evaluation highlights the necessity of conducting a statistical assessment to determine an estimate for the distribution of the acceleration limit and model uncertainty for dynamic analyses. The results show that the required damping coefficient could be multiply reduced, as compared to a deterministic analysis., QC 20210112

The information contained in this paper will be of interest not only to bridge engineers, but also to train manufacturers. The article provides practical insight into the degree of coverage of real articulated trains (ATs) that Eurocode EN1991-2 guarantees. In both the design of new railway bridges, as well as in the assessment of existing ones, the importance of a detailed knowledge of the limits of validity of load models cannot be overemphasised. Being essential components of the rail transportation system, the capacity of bridges to withstand future traffic demands will be determined precisely by the load models. Therefore, accurate definition of the limits of validity of such models reveals crucial when increased speeds and/or increased axle loads are required by transportation pressing priorities. The most relevant load model for a significant portion of the bridges in high-speed railway lines is the so-called HSLM-A model, defined in EN1991-2. Their limits of validity are described in Annex E of such code. For its singular importance, the effects of vibrations induced by HSLM-A are analysed in this paper with attention to the response of simply supported bridges. This analysis is carried out in a view to determine whether the limits of validity given in Annex E of EN1991-2 cover the largest part of cases of interest. Specifically, the vibration effects of HSLM-A are compared with those of the ATs described in such Annex E, and the response is analysed in depth for simply supported bridges, which are structures especially sensitive to passing trains at high speeds. New theoretical approaches have been developed in order to undertake this investigation, including a novel, simplified expression of the train signature for ATs that is convenient for its low computational cost. The mathematical proofs are included in the first part of the paper and two separate appendices., QC 20201210

The influence of dynamic soil-structure interaction (SSI) on simply supported railway bridges is investigated. Impedance functions are calculated considering shallow foundations in soil strata limited by bedrock. The impedance functions are coupled to bridge models, and the assembled soil-bridge systems are investigated addressing the modal properties. A parametric study is performed on a large set of soil-bridge systems. Finally, the response to train loading is analysed. The study shows that the effects of SSI are essentially different depending on whether radiation damping is active or not. Shorter bridges are often affected by radiation damping and the response due to train loading may be significantly reduced when SSI is considered. However, for longer bridges (>15 m) the effect of SSI is often small. Due to the stiffness reduction of the impedance, some bridges may even have a detrimental effect from SSI and a reduction of the traffic speed is obtained., QC 20211005

[EN] The information contained in this paper will be of interest not only to bridge engineers, but also to train manufacturers. The article provides practical insight into the degree of coverage of realarticulated trains(ATs) that Eurocode EN1991-2 guarantees. In both the design of new railway bridges, as well as in the assessment of existing ones, the importance of a detailed knowledge of thelimits of validityofload modelscannot be overemphasised. Being essential components of the rail transportation system, the capacity of bridges to withstand future traffic demands will be determined precisely by the load models. Therefore, accurate definition of the limits of validity of such models reveals crucial when increased speeds and/or increased axle loads are required by transportation pressing priorities. The most relevant load model for a significant portion of the bridges in high-speed railway lines is the so-called HSLM-A model, defined in EN1991-2. Their limits of validity are described in Annex E of such code. For its singular importance, the effects of vibrations induced by HSLM-A are analysed in this paper with attention to the response ofsimply supported bridges. This analysis is carried out in a view to determine whether the limits of validity given in Annex E of EN1991-2 cover the largest part of cases of interest. Specifically, the vibration effects of HSLM-A are compared with those of the ATs described in such Annex E, and the response is analysed in depth for simply supported bridges, which are structures especially sensitive to passing trains at high speeds. New theoretical approaches have been developed in order to undertake this investigation, including a novel, simplified expression of thetrain signaturefor ATs that is convenient for its low computational cost. The mathematical proofs are included in the first part of the paper and two separate appendices.

The dynamic response of railway bridges is important to consider, as the high velocity loading from the trains increases the risk of resonance. Increasing train speeds and loads result in a need for adaptable properties for railway bridges. One solution is to install magnetorheological dampers, as the response of the structure originating from moving loads could be controlled by alternating the input current to the damper. However, the complexity of such devices results in difficulties to accurately model their behaviour. From this context, real-time hybrid simulations, consisting of a numerical bridge model and a full-scale physical magnetorheological damper in a test frame, are presented in this paper. The novelty of the present paper is the application of RTHS in railway bridge engineering and the substructure combination with magnetorheological dampers. The results from the real-time hybrid simulations show that the bridge deck responses can be reduced to permissible levels. ., QC 20220427

© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Doo, S. S., Kealoha, A., Andersson, A., Cohen, A. L., Hicks, T. L., Johnson, Z., I., Long, M. H., McElhany, P., Mollica, N., Shamberger, K. E. F., Silbiger, N. J., Takeshita, Y., & Busch, D. S. The challenges of detecting and attributing ocean acidification impacts on marine ecosystems. ICES Journal of Marine Science, 77(7-8), (2020): 2411-2422, https://doi.org/10.1093/icesjms/fsaa094., A substantial body of research now exists demonstrating sensitivities of marine organisms to ocean acidification (OA) in laboratory settings. However, corresponding in situ observations of marine species or ecosystem changes that can be unequivocally attributed to anthropogenic OA are limited. Challenges remain in detecting and attributing OA effects in nature, in part because multiple environmental changes are co-occurring with OA, all of which have the potential to influence marine ecosystem responses. Furthermore, the change in ocean pH since the industrial revolution is small relative to the natural variability within many systems, making it difficult to detect, and in some cases, has yet to cross physiological thresholds. The small number of studies that clearly document OA impacts in nature cannot be interpreted as a lack of larger-scale attributable impacts at the present time or in the future but highlights the need for innovative research approaches and analyses. We summarize the general findings in four relatively well-studied marine groups (seagrasses, pteropods, oysters, and coral reefs) and integrate overarching themes to highlight the challenges involved in detecting and attributing the effects of OA in natural environments. We then discuss four potential strategies to better evaluate and attribute OA impacts on species and ecosystems. First, we highlight the need for work quantifying the anthropogenic input of CO2 in coastal and open-ocean waters to understand how this increase in CO2 interacts with other physical and chemical factors to drive organismal conditions. Second, understanding OA-induced changes in population-level demography, potentially increased sensitivities in certain life stages, and how these effects scale to ecosystem-level processes (e.g. community metabolism) will improve our ability to attribute impacts to OA among co-varying parameters. Third, there is a great need to understand the potential modulation of OA impacts through the, SSD was funded by NSF OCE (grant # 1415268). DSB and PM were supported by the NOAA Ocean Acidification Program and Northwest Fisheries Science Center, MHL was supported by NSF OCE (grant # 1633951), ZIJ was supported by NSF OCE (grant # 1416665) and DOE EERE (grant #DE-EE008518), NJS was supported by NSF OCE (grant # 1924281), ALC was supported by NSF OCE (grant # 1737311), and AA was supported by NSF OCE (grant # 1416518). KEFS, AK, and TLH were supported by Texas A&M University. This is CSUN Marine Biology contribution (# 306).

Limiting the maximum vertical acceleration and deflection of the deck are two principal design criteriaof high-speed railway bridges. The former prevents ballast instability to ensure running safety, andthe latter attempts to limit the acceleration of the car-body below the level at which passengercomfort is disturbed. The previous studies are mainly concerned with the destabilization of the ballast,nevertheless the possibility of the maximum deflection occurrence should not be underestimated.Moreover, the literature indicates the need to improve the current design requirements including theminimum allowable mass and frequency of bridges, which requires solving optimization problems basedon modern requirements. Therefore, a probabilistic framework with simulation-based techniques is usedto evaluate the violation probability of the above limit states and distinguish dominant criteria underdifferent conditions, i.e., bridge span length and operational train speed. First, the performance of thesubset simulation method is compared with the Latin Hypercube-sampling based Monte-Carlo approachsupported by surrogate models. Polynomial chaos expansion (PCE) surrogate models are trained for thisobjective. Then, the resulting violation probabilities are evaluated for the two considered limit statesusing the approach with better performance., Priceedings ISBN: 978-981-18-2016-8, QC 20211011

Gemenskap kan förstås delvis som ett enhetligt plats-baserat väsen man kan kalla lokalsamhället, vars beståndsdelar förgrenar sig till fler mindre gemenskaper. Tillsammans samverkar gemenskaperna mot olika mål som för samhället åt olika håll. Denna studie har riktat sig på att undersöka ett lokalsamhälle, under en period av svår lågkonjunktur till följd av den ekonomiska krisen som rådde under 70-talet, för att se hur dessa jobbar enskilt och tillsammans. Två nedläggningar av lokala industriföretag från Säffle studerades genom undersökningar hur kommun, fackförbund och lokaltidning arbetade genom deras krisår mot nedläggning.

This paper presents dynamic measurements performed on two pedestrian bridges inSweden subjected to different loading scenarios. Using accelerometers, the natural frequencies,the experimental mode shapes and damping properties were determined for each bridge. Analysiswere performed using the generalized single degree of freedom theory, the finite elementmethod and the coupled system approach taking into account the flying phase of the runningload. Additionaly, a simplified sensitivity analysis is presented in terms of accelerations dueto the pedestrian transient event of a running load case. The results indicate that there is anexcellent agreement between the aforementioned modelling strategies and, that it is possible tohave human structure interaction under running load scenarios., QC 20210824

The transition from preclinical biological drug development into clinical trials requires an efficient upscaling process. In this context, bispecific antibody drugs are particularly challenging due to their propensity to form aggregates and generally produce low titers. Here, the upscaling process for a tetravalent bispecific antibody expressed by a piggyBac transposon-mediated stable HEK293 cell pool has been evaluated. The project was performed as a case study at Testa Center, a non-GMP facility for scale-up testing of biologics in Sweden, and encompassed media adaptation strategies, fed-batch optimization and a novel antibody purification technology. The cell pool was adapted to different culture media for evaluation in terms of cell viability and titers compared to its original Expi293 Expression Medium. These parameters were assessed in both sequential stepwise adaption and direct media exchanges. By this, a more affordable medium was identified that did not require stepwise adaptation and with similar titers and viability as in the Expi293 Expression Medium. Fed-batch optimizations resulted in culture densities reaching up to 20 x 106 viable cells/mL with over 90 % viability 12 days postinoculum, and antibody titers three times higher than corresponding batch cultures. By implementing a novel high-speed protein A fiber technology (Fibro PrismA) with a capture residence time of only 7.5 s, 8 L of supernatant could be purified in 4.5 h without compromising the purity, structural integrity and function of the bispecific antibody. Results from this study related to medium adaptation and design of fed-batch protocols will be highly beneficial during the forthcoming scale-up of this therapeutic antibody.

The hydrodynamics within small boreal lakes have rarely been studied, yet knowing whether turbulence at the air-water interface and in the water column scales with metrics developed elsewhere is essential for computing metabolism and fluxes of climate-forcing trace gases. We instrumented a humic, 4.7 ha, boreal lake with two meteorological stations, three thermistor arrays, an infrared (IR) camera to quantify surface divergence, obtained turbulence as dissipation rate of turbulent kinetic energy (epsilon) using an acoustic Doppler velocimeter and a temperature-gradient microstructure profiler, and conducted chamber measurements for short periods to obtain fluxes and gas transfer velocities (k). Near-surface epsilon varied from 10(-8) to 10(-6) m(2) s(-3) for the 0-4 m s(-1) winds and followed predictions from Monin-Obukhov similarity theory. The coefficient of eddy diffusivity in the mixed layer was up to 10(-3) m(2) s(-1) on the windiest afternoons, an order of magnitude less other afternoons, and near molecular at deeper depths. The upper thermocline upwelled when Lake numbers (L-N) dropped below four facilitating vertical and horizontal exchange. k computed from a surface renewal model using epsilon agreed with values from chambers and surface divergence and increased linearly with wind speed. Diurnal thermoclines formed on sunny days when winds were < 3 m s(-1), a condition that can lead to elevated near-surface epsilon and k. Results extend scaling approaches developed in the laboratory and for larger water bodies, illustrate turbulence and k are greater than expected in small wind-sheltered lakes, and provide new equations to quantify fluxes.

From observations in a High Arctic valley and ice-free fjord in Svalbard during March and April 2013 we show that, while some caution needs to be applied, ordinary slow-response instruments placed over a snow-water-snow surface can be effectively used as a proxy for more sophisticated measuring techniques at complex sites such as leads or a polynyas. The turbulent fluxes of momentum, sensible and latent heat were measured at three locations with a snow-water-snow fetch. At the snow site upwind of the water, the stability was generally stable, the momentum flux small, and the sensible heat flux positive. Over the water however, the internal boundary layer that was formed gave on average an increased vertical gradient in wind speed, temperature, and humidity and turbulent heat fluxes exceeding 400 W m−2. At the snow surface downwind of the water, the conditions were highly variable and all the fluxes were, on average, of very small magnitude. That the behaviour of the internal boundary layers can be highly variable is demonstrated through four case studies. This phenomenon is likely to increase in occurrence with a changing climate.

The operational speed of the trains is intended to be significantly increasedforthcoming; which consequently questions the safety level of the current design conceptsconcerning different performance limits. Thus, the reliability of the simply supportedsingle-span bridges is assessed in the current article adopting the first-order reliabilitymethod (FORM) approach. In this regard, the dynamic response of the aimed bridges isinvestigated under the passage of a series of moving loads using available closed-form solutions in the literature. Hereof, axle load, car body/train configuration, flexural rigidity,damping, mass and model uncertainties are considered as random variables; while traintrack-bridge interactions are neglected and the procedure is repeated for a wide range ofspan lengths and train velocities. Then, the safety index corresponding to each case isevaluated by considering running safety as the limit state function; where, the bridge deckvertical acceleration is taken as the capacity of the system. The outcomes are presentedas average probability of exceeding the limit state versus train speed and categorized basedon span lengths., Not duplicate with DiVA 1552464QC 20201216, Shift2Rail

The objective of this study is to evaluate the vibratory response of two-span continuous beams subjected tomoving loads and, in particular, to investigate the maximum resonance and cancellation of resonance phenomena.The main practical interest is the evaluation of the maximum acceleration response in railway bridges,which is one of the most demanding Serviceability Limit States for traffic safety according to current regulations.Two-span continuous bridges, in their simplest version (i.e. uniform identical spans), present antisymmetric andsymmetric modes with closely spaced natural frequencies, leading to a more involved dynamic behaviour thanthat of simply-supported bridges. First, the free vibration response of a Bernoulli-Euler two-span beam after thepassage of a single load at constant speed is formulated analytically, and non-dimensional speeds leading tocancellation or maximum response in free vibration are obtained for each mode. Then, these conditions areequated to resonant speeds induced by equidistant load series, and span length-to-characteristic distance ratioscausing cancelled out resonances, or remarkably prominent ones, are obtained. Based on the previous derivations,a methodology for detecting which could be the most aggressive trains for a particular structure based onpure geometrical considerations is discussed. Finally, the applicability of the theoretical derivations is shownthrough the numerical analysis of two real bridges belonging to the Swedish railway network., QC 20200916

The information contained in this paper will be of interest not only to bridge engineers, but also to train manufacturers.The article provides practical insight into the degree of coverage of real articulated trains (ATs) that Eurocode EN1991-2guarantees. In both the design of new railway bridges, as well as in the assessment of existing ones, the importance of adetailed knowledge of the limits of validity of load models cannot be overemphasised. Being essential components of therail transportation system, the capacity of bridges to withstand future traffic demands will be determined precisely bythe load models. Therefore, accurate definition of the limits of validity of such models reveals crucial when increasedspeeds and/or increased axle loads are required by transportation pressing priorities. The most relevant load model fora significant portion of the bridges in high-speed railway lines is the so-called HSLM-A model, defined in EN1991-2. Theirlimits of validity are described in Annex E of such code. For its singular importance, the effects of vibrations induced byHSLM-A are analysed in this paper with attention to the response of simply supported bridges. This analysis is carried outin a view to determine whether the limits of validity given in Annex E of EN1991-2 cover the largest part of cases ofinterest. Specifically, the vibration effects of HSLM-A are compared with those of the ATs described in such Annex E, andthe response is analysed in depth for simply supported bridges, which are structures especially sensitive to passing trainsat high speeds. New theoretical approaches have been developed in order to undertake this investigation, including anovel, simplified expression of the train signature for ATs that is convenient for its low computational cost. The mathematicalproofs are included in the first part of the paper and two separate appendices., QCR 20200923

The influence of model assumptions on the dynamic impedance functions of shallow foundations is investigated using finite elements in two studies. The first investigates the effects of model assumptions in different combinations including embedment of the foundation, variation of modulus with depth, and permanent load acting on the foundation. The second study is a parametric analysis investigating the effects of permanent load at varying soil depths and with different soil modulus coefficients. Shallow foundations in strata of frictional soil on top of bedrock are considered. Small-strain modulus and modulus reduction relationships are used in an iterative process to update the modulus due to the permanent load. The results show that model assumptions can have a large influence on impedance functions. The static stiffness coefficients differ, in some instances by more than 100%. The impedance functions, normalized with the static stiffness coefficients match each other well in the pre-resonance frequency range. However, in the frequency range above the fundamental frequency, the normalized impedance functions show a large variation. Further, the results show that the influence of the permanent load is largest in the case of shallow and stiff soil strata, both regarding normalized impedance functions as well as the static stiffness coefficient, which can be increased up to 67%. The change in fundamental frequency was however minimal., QC 20200922

The influence of dynamic soil-structure interaction (SSI) on simply supported railway bridges is investigated. Impedance functions are calculated considering shallow foundations in soil strata limited by bedrock. The impedance functions are coupled to bridge models, and the assembled soil-bridge systems are investigated addressing the modal properties. A parametric study is performed on a large set of soil-bridge systems. Finally, the response to train loading is analysed. The study shows that the effects of SSI are essentially different depending on whether radiation damping is active or not. Shorter bridges are often affected by radiation damping and the response due to train loading may be significantly reduced when SSI is considered. However, for longer bridges (>15 m) the effect of SSI is often small. Due to the stiffness reduction of the impedance, some bridges may even have a detrimental effect from SSI and a reduction of the traffic speed is obtained., QC 20200922Syskonpost till ID: diva2:1600518 (published)

To analyze the mesodynamic and macrodynamic performance of the track transitions more precisely, a bridge-embankment transition model has been established by combining the discrete element method (DEM) with the finite difference method (FDM). In this model, the DEM is utilized to model sleepers and ballast particles with complex shape, and the FDM is applied to simulate the abutment, transition section and embankment. The DEM/FDM coupled model is then achieved by exchanging displacements, velocities, and contact forces at the interface. Afterwards, the influence of the transition section parameters and transition forms on dynamic behaviour of the track-substructure system is studied under measured rail seat load. The numerical simulations indicate that the increase of the transition section elastic modulus, decrease of the backfill slope values and the transition form of trapezoid backfill following by inverted trapezoid backfill can provide a better displacement gradient between the abutment and the embankment. Additionally, the results show that the inverted trapezoid transition form can provide a better transition of the track dynamic performance than the trapezoid transition form and the embankment soil over the wedge-shape backfill has the tendency to propagate along the slope toward the embankment section under the moving train load for the trapezoid transition form., QC 20200427

This report present a load effect analysis of 35 railway bridges on the iron ore lineMalmbanan. Many of these bridges were originally designed for 25 tonnes axle loador less and is currently the subject of an upgrade to 32.5 tonnes axle load. The mainaim of this study is to explore if the dynamic amplification factor can be decreasedfor the new trains at a speed of 70 km/h.Dynamic effects are often accounted for by a dynamic amplification factor of thestatic response. For real trains EN 1991-2 defines ϕ′ as a dynamic impact componentand ϕ′′ as additional dynamic effects from track irregularities.

Skattning av skogliga variabler är inte längre begränsade till datainsamling genom manuell fältmätning. Numera kan skattningar göras genom insamling av data från såväl laserskanning (Airborne Laser Scanning, ALS) som mobilapplikationen Katam Forest (KF) som företaget Katam utvecklat. Dessutom kan varje enskilt träd skattas genom att kombinera Katam Treemap (KT), som använder sig av fotogrammetri för att mäta trädhöjd och identifiera träd, med KF (KF+KT) . I denna studie jämfördes skattningar av grundytevägd medeldiameter (DGV) och grundyta (GY) utförda med manuell fältmätning, ALS, KF samt KF+KT, i tre olika grandominerande bestånd. KF+KT beräknades felaktigt varför inga slutsatser kan dras om metoden. KF visade ett lägre relativt RMSE än ALS, 7,8 % jämfört med 9,6 % vid skattning av DGV. För GY var relativ RMSE 22,5 % vid KF, och 23 % vid ALS. KF bedöms med fördel kunna användas likvärdigt med manuell fältmätning.

I denna studie undersöks hur svenska hotellreceptionister upplever de strukturella villkoren som hotell – och restaurangnäringen arbetar under, om de villkoren påverkar hur de kan balansera sitt arbetsliv med ett meningsfullt privatliv. Studien görs av två olika anledningar, dels för att täcka en kunskapslucka gällande ett svenskt perspektiv på hur hotellreceptionister upplever sitt arbetsliv, då det har varit avsaknad sen tidigare. Den tidigare forskningen har varit centraliserad runt Asien, Oceanen och USA. Studien görs även för att upplysa hur arbetstagare i yrken inom service- och tjänstesektorn upplever sitt arbetsliv. Frågeställningar som har använts är: Hur upplevs arbetsplatsrelationerna? Hur upplevs de strukturella arbetsvillkoren inom yrket? Hur upplevs balansen mellan arbetsliv och privatliv? De teoretiska utgångspunkterna utgörs av forskning som berör socialt hållbart arbetsliv, värdigt arbetsliv och livskvalitet i arbetslivet. Metoden som har använts är kvalitativ metod. Inom studien har semistrukturerade intervjuer använts för att få fram slutsatser om hur hotellreceptionister upplever sitt arbetsliv. I studien intervjuas 8 hotellreceptionister som har arbetat mer än ett år i en hotellreception. Det finns bra och mindre bra arbetsplatsrelationer som har en inverkan på arbetsklimatet, de närmaste kollegorna bidrar till ett bra arbetsklimat. Den dåliga kommunikationen mellan avdelningarna, och i vissa fall upplevda brister i ledningen, och arbetsplatsstressen som informanterna upplever, bidrar till ett försämrat arbetsklimat för informanterna. De strukturella arbetsvillkoren hämnar informanternas frihetskänsla på grund av att de inte kan vara med och styra över sina arbetstider och den arbetsmiljö de arbetar i, utan de får acceptera de strukturella arbetsvillkoren. Dessa villkor hämmar även privatlivet och gör det svårt att kombinera ett hotellreceptionistjobb med ett meningsfullt privatliv.

Studiens syfte är att bidra med en översikt av hur rektorer beskriver sitt pedagogiska ledarskap i fritidshemmet. De forskningsfrågor som har använts är: • Vad beskriver rektorer som viktiga kvalitéer och förmågor i det pedagogiska ledarskapet i fritidshemmets verksamhet? • Hur arbetar rektorer för att leda fritidshemmets verksamhet? En kvalitativ metod har använts när den empiriska datan har samlats in genom fem semistrukturerade intervjuer med verksamma rektorer från olika skolområden inom samma kommun. Datan har analyserats genom en kvalitativ innehållsanalys. Analysprocessen har inhämtat inspiration från fenomenologin. Det som framgick i resultatet var att rektorer anser det som viktigt med en tydlig kommunikation och att personalen får vara delaktiga i beslutsfattning. De påtalar även vikten av att lyfta fritidspersonalens kompetenser och att detta kräver en förkunskap om fritidshemmets verksamhet. Rektorerna berättar att de delegerar ansvar och vill fungera som ett stöd i strävan på en självorganisering.

Dataset: Bermuda annual coral growth rates, Annual linear extension, skeletal density, and calcification rate data are reported for coral cores collected from across Bermuda in 2016. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/821212, NSF Division of Ocean Sciences (NSF OCE) OCE-1829778

A substantial body of research now exists demonstrating sensitivities of marine organisms to ocean acidification (OA) in laboratory settings. However, corresponding in situ observations of marine species or ecosystem changes that can be unequivocally attributed to anthropogenic OA are limited. Challenges remain in detecting and attributing OA effects in nature, in part because multiple environmental changes are co-occurring with OA, all of which have the potential to influence marine ecosystem responses. Furthermore, the change in ocean pH since the industrial revolution is small relative to the natural variability within many systems, making it difficult to detect, and in some cases, has yet to cross physiological thresholds. The small number of studies that clearly document OA impacts in nature cannot be interpreted as a lack of larger-scale attributable impacts at the present time or in the future but highlights the need for innovative research approaches and analyses. We summarize the general findings in four relatively well-studied marine groups (seagrasses, pteropods, oysters, and coral reefs) and integrate overarching themes to highlight the challenges involved in detecting and attributing the effects of OA in natural environments. We then discuss four potential strategies to better evaluate and attribute OA impacts on species and ecosystems. First, we highlight the need for work quantifying the anthropogenic input of CO2 in coastal and open-ocean waters to understand how this increase in CO2 interacts with other physical and chemical factors to drive organismal conditions. Second, understanding OA-induced changes in population-level demography, potentially increased sensitivities in certain life stages, and how these effects scale to ecosystem-level processes (e.g. community metabolism) will improve our ability to attribute impacts to OA among co-varying parameters. Third, there is a great need to understand the potential modulation of OA impacts through the

In this work, the effect of the surrounding soil condition on the fundamental modal characteristics and dynamic response of railway bridges with integral abutments is studied. Due to the computational cost of the full FE models and the lack of reliable simplified models, the effect of the soil-structure interaction is usually neglected in the vibration analysis of the high-speed railway bridges. In the present study, an efficient simplified numerical model is employed to evaluate the modal characteristics of the railway bridge-soil systems. After verifying the accuracy of the simplified numerical model against rigorous models, the effect of the span length and abutment/soil stiffness on the dynamic response of the studied bridges is investigated through a comprehensive parametric study. Several case studies which covers different span lengths and abutment conditions are chosen. It is shown that the SSI has substantial effect on the dynamic response of the short and stiff bridges while its effect decreases as the ratio between the deck stiffness and the abutment/soil stiffness decreases. The results may lead to review the recommended modal damping ratios for this type of bridges in the code provisions and design manuals., QC 20211003

Corrugated steel culverts are sometimes used as an alternative to portal frame bridges for small and medium crossings under railway lines. From a static point of view, the corrugated steel culverts are rather flexible structures and the load capacity relies on the confinement from the surrounding soil. From a dynamic point of view, especially for potential use on high-speed lines, the structural manner of action is not yet fully explored. This paper presents the result from full-scale experimental testing of a corrugated steel culvert, including both forced vibration tests and response from passing trains. The aim is to estimate the dynamic characteristics of the bridge, especially the interaction with the surrounding soil and how that will influence the response at the track level. From the forced vibration tests, the results show that the structure has a high inherent damping owing to the surrounding soil and that both the natural frequency and damping change with load amplitude. The experimental frequency response functions are used for updating numerical models to further understand the dynamic behaviour of these structures., QC 20211001

This paper presents an analytical approximation to describe the vertical and horizontal vibrations of clamped-clamped beams subjected to a single pedestrian induced load. No intra—person variability is considered and only a single crossing is taken into account. This approximation is performed by choosing a suitable trigonometric function that well estimates the dynamic properties and mode shape of the system. Moreover, the approximation enables to find the relationship between the loading parameters such as the step frequency and velocity and, the dynamic properties of the system as the natural frequency and damping. Furthermore, approximation formulas are presented for peak displacements, velocities and accelerations in the damped, low damped and undamped cases. Finally, amplifications factors and minimum design mass curves are defined using non dimensional parameters, aiming to contribute to a fast pedestrian bridge dynamic assessment for systems whose mode shapes reassemble the mode shape of a clamped—clamped beam, for both walking and running pedestrian load cases., QC 20211001

The effects of model assumptions on the dynamic impedance junctions of shallow foundations are investigated using finite elements. The shallow foundations are considered massless and rigid and are positioned in strata of frictional soil on top of bedrock. Two studies are established. The first investigates the combined effects of model assumptions including the variation of modulus with depth, the embedment of the foundation, and permanent load acting on the foundation. The second study is a parametric analysis investigating the effects of permanent load considering strata with varying soil modulus coefficients and with varying soil depths. Functions describing the small-strain modulus and the modulus reduction of frictional soil are used in an iterative process to update the spatial modulus distribution of the soil due to the permanent load. The results show that model assumptions can have a large effect on the impedance functions. The static stiffness coefficients vary substantially, in some instances by more than 100 %. The impedance functions, normalized with the static stiffness coefficients, match each other well in the frequency range below the fundamental frequency. However, in the frequency range above the fundamental frequency, the normalized impedance functions differ substantially from each other. Further, the results show that the effect of the permanent load is largest in the case of shallow and stiff soil strata, both regarding normalized impedance functions as well as the static stiffness coefficient, which was increased up to 67 %. The variation in fundamental frequency is however small., QC 20210505

This paper deals with the dynamic response of railway bridges traversed by articulated trains, specifically the interaction effect between the coach length D and bogie distance dBA. Current design code EN 1991-2 stipulate that the ratio D/dBA should not be close to an integer value, but no further guidance is given. By using train signatures and a so-called bogie factor, the combined effect is illustrated in a non-dimensional domain. The results are also presented by realistic examples which show that integer ratios of D/dBA are not necessarily worse than non-integer ratios. This is further confirmed by a parametric study of simply supported beams and ranges of train parameters according to EN 1991-2 Annex E., QC 20210505

Supplement: 1Meeting Abstract: P23.06.C