| 1. |
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| 2. |
- Dorigo, Wouter, et al.
(författare)
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The International Soil Moisture Network : Serving Earth system science for over a decade
- 2021
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Ingår i: Hydrology and Earth System Sciences. - : Copernicus GmbH. - 1027-5606 .- 1607-7938. ; 25:11, s. 5749-5804
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Forskningsöversikt (refereegranskat)abstract
- In 2009, the International Soil Moisture Network (ISMN) was initiated as a community effort, funded by the European Space Agency, to serve as a centralised data hosting facility for globally available in situ soil moisture measurements . The ISMN brings together in situ soil moisture measurements collected and freely shared by a multitude of organisations, harmonises them in terms of units and sampling rates, applies advanced quality control, and stores them in a database. Users can freely retrieve the data from this database through an online web portal (https://ismn.earth/en/, last access: 28 October 2021). Meanwhile, the ISMN has evolved into the primary in situ soil moisture reference database worldwide, as evidenced by more than 3000 active users and over 1000 scientific publications referencing the data sets provided by the network. As of July 2021, the ISMN now contains the data of 71 networks and 2842 stations located all over the globe, with a time period spanning from 1952 to the present. The number of networks and stations covered by the ISMN is still growing, and approximately 70 % of the data sets contained in the database continue to be updated on a regular or irregular basis. The main scope of this paper is to inform readers about the evolution of the ISMN over the past decade, including a description of network and data set updates and quality control procedures. A comprehensive review of the existing literature making use of ISMN data is also provided in order to identify current limitations in functionality and data usage and to shape priorities for the next decade of operations of this unique community-based data repository.
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| 3. |
- Hudson, Thomas J., et al.
(författare)
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International network of cancer genome projects
- 2010
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 464:7291, s. 993-998
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Tidskriftsartikel (refereegranskat)abstract
- The International Cancer Genome Consortium (ICGC) was launched to coordinate large-scale cancer genome studies in tumours from 50 different cancer types and/or subtypes that are of clinical and societal importance across the globe. Systematic studies of more than 25,000 cancer genomes at the genomic, epigenomic and transcriptomic levels will reveal the repertoire of oncogenic mutations, uncover traces of the mutagenic influences, define clinically relevant subtypes for prognosis and therapeutic management, and enable the development of new cancer therapies.
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| 4. |
- Pinto, Dalila, et al.
(författare)
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Functional impact of global rare copy number variation in autism spectrum disorders.
- 2010
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 466:7304, s. 368-372
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Tidskriftsartikel (refereegranskat)abstract
- The autism spectrum disorders (ASDs) are a group of conditions characterized by impairments in reciprocal social interaction and communication, and the presence of restricted and repetitive behaviours. Individuals with an ASD vary greatly in cognitive development, which can range from above average to intellectual disability. Although ASDs are known to be highly heritable ( approximately 90%), the underlying genetic determinants are still largely unknown. Here we analysed the genome-wide characteristics of rare (<1% frequency) copy number variation in ASD using dense genotyping arrays. When comparing 996 ASD individuals of European ancestry to 1,287 matched controls, cases were found to carry a higher global burden of rare, genic copy number variants (CNVs) (1.19 fold, P = 0.012), especially so for loci previously implicated in either ASD and/or intellectual disability (1.69 fold, P = 3.4 x 10(-4)). Among the CNVs there were numerous de novo and inherited events, sometimes in combination in a given family, implicating many novel ASD genes such as SHANK2, SYNGAP1, DLGAP2 and the X-linked DDX53-PTCHD1 locus. We also discovered an enrichment of CNVs disrupting functional gene sets involved in cellular proliferation, projection and motility, and GTPase/Ras signalling. Our results reveal many new genetic and functional targets in ASD that may lead to final connected pathways.
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| 5. |
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| 6. |
- Bader, Thomas K., 1980-, et al.
(författare)
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Dowel deformations in multi-dowel LVL-connections under moment loading
- 2015
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Ingår i: Wood Material Science & Engineering. - : Taylor & Francis. - 1748-0272 .- 1748-0280. ; 10:3, s. 216-231
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the experimental study presented herein is the assessment and quantification of the behavior of individual dowels in multi-dowel connections loaded by a bending moment. For this purpose, double-shear, steel-to-timber connections with nine steel dowels arranged in different patterns and with different dowel diameters were tested in four-point bending. In order to achieve a ductile behavior with up to 7° relative rotation, the connections were partly reinforced with self-tapping screws. The reinforcement did not influence the global load–deformation behavior, neither for dowel diameters of 12 mm nor for 20 mm, as long as cracking was not decisive. The deformation of the individual dowels was studied by means of a non-contact deformation measurement system. Thus, the crushing deformation, that is, the deformation at the steel plate, and the bending deformation of the dowels could be quantified. In the case of 12 mm dowels, the bending deformation was larger than the crushing deformation, while it was smaller in the case of 20 mm dowels. Moreover, dowels loaded parallel to the grain showed larger bending deformations than dowels loaded perpendicular to the grain. This indicates that the loading of the individual dowels in the connection differs depending on their location.
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| 7. |
- Bader, Thomas K., 1980-, et al.
(författare)
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Experimental Assessment of the Load Distribution in Multi-Dowel Timber Connections
- 2016
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Ingår i: 17th International Conference on Experimental Mechanics, Rhodes, Greece, July 3-7, 2016.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- An integrative, hierarchically organized testing procedure for the quantification of the load distribution in multi-dowel timber connections is presented herein. The use of contactless deformation measurement systems allowed the combination of test data from single dowel and multi-dowel connections, which gave access to the loads acting on each dowel over the full loading history. As a consequence of the anisotropic material behavior of wood, a nonuniform and progressively changing load distribution among the dowels was found.
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| 8. |
- Bader, Thomas K., 1980-, et al.
(författare)
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Experimental characterization of the global and local behavior of multi-dowel LVL-connections under complex loading
- 2016
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Ingår i: Materials and Structures. - : Springer Science and Business Media LLC. - 1359-5997 .- 1871-6873. ; 49:6, s. 2407-2424
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Tidskriftsartikel (refereegranskat)abstract
- The thorough experimental characterization of a dowel-type connection under various combinations of bending moments and normal forces is presented in this study. Double-shear steel-to-timber connections with 12 and 20 mm steel dowels were tested in a 4-point bending test set-up. The load, between the connected steel and wood beams, was transferred by the dowels themselves and also via an additional (passive) contact device, which introduced an eccentric normal force in the timber beam. The behavior of the connections was studied at the global scale of the connection and at the local scale of the individual dowels. A non-contact deformation measurement system was used to assess the changes of the location of the center of relative rotation over the entire loading. At the same time, the head deformations of the individual dowels could be measured, giving a direct indication about the force distribution among the dowels. Due to reinforcement, connections behaved distinctly ductile with a global relative rotation of up to 3°. Pre-stressing of the contact device by a force of 40 kN yielded an even stiffer behavior. For the particular configurations tested herein, the center of rotation was found to be close to the vertical axis of symmetry of the joint and close to the top row of the dowels. Moreover, the superimposed vertical shift of the center of relative rotation in case of a delayed normal force could be quantified. © 2015 RILEM
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| 9. |
- Bader, Thomas K., et al.
(författare)
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Integrative experimental characterization and engineering modeling of single-dowel connections in LVL
- 2016
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Ingår i: Construction and Building Materials. - : Elsevier BV. - 0950-0618 .- 1879-0526. ; 107, s. 235-246
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Tidskriftsartikel (refereegranskat)abstract
- In order to be able to realistically and consistently elucidate and subsequently simulate the load displacement behavior of single-dowel connections, the material behavior of the individual components, namely steel dowels and wood, needs to be investigated. The behavior of slotted-in, single-dowel steel-to-laminated veneer lumber (LVL) connections with dowel diameters of 12 and 20 mm is thoroughly discussed here in relation to steel dowel and LVL properties. In addition to connection tests at different load-to-grain directions of 0, 45 and 90, the corresponding embedment behavior of LVL was tested up to dowel displacements of three times the dowel diameter. The material behavior of steel dowels was studied by means of tensile and 3-point bending tests and accompanying finite element simulations. A pronounced nonlinear behavior of the single-dowel connections was observed for all load-to-grain directions. In case of loading perpendicular to the grain, a significant hardening behavior was obvious. Due to the anisotropic material properties of wood, enforcing a loading direction of 45 to the grain resulted in an additional force perpendicular to the load direction which was quantified in a novel biaxial test setup. Thus, a comprehensive and consistent database over different scales of observations of dowel connections could be established, which subsequently was exploited by means of engineering modeling. The comparison of experimental and numerical data illustrates the potential of the engineering modeling approach to overcome drawbacks of current design regulations, which are unable to appropriately predict stiffness properties of dowel connections. Moreover, the quasi-elastic limit of dowel connections was calculated and discussed by means of the model. (c) 2016 Elsevier Ltd. All rights reserved.
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| 10. |
- Denkinger, Michael D., et al.
(författare)
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Does functional change predict the course of improvement in geriatric inpatient rehabilitation?
- 2010
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Ingår i: Clinical Rehabilitation. - : SAGE Publications. - 0269-2155 .- 1477-0873. ; 24:5, s. 463-470
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Tidskriftsartikel (refereegranskat)abstract
- Objective: The evaluation of rehabilitation success as measured by different tools is becoming increasingly important in terms of time and money allocation. We wanted to know whether functional change in the first week predicts subsequent improvement in a geriatric inpatient rehabilitation clinic. Design: Observational longitudinal study. Setting: Geriatric inpatient rehabilitation clinic in Germany. Subjects: One hundred and sixty-one inpatients (117 women) with a median age of 82 years, capable of walking at baseline. Main measures: Weekly assessments of physical function were performed from admission until three weeks later. We used a self-rated tool (the function component of the Short Form - Late Life Function and Disability Index), a proxy-rated tool (the Barthel Index) and a performance-based tool (gait speed). We set up linear regression models to estimate the predictive capacity of change in physical function within the first week on change in physical function within the following two weeks. Results: Positive correlations were found between functional change within the first week and total change within three weeks. However, correlations of the same periods of change with subsequent change were negative. Correlations were highly significant for both analysis with P-values < 0.0001 when the same measures for prediction and outcome were used. Correlations were inconsistent when prediction and outcome were different. Conclusions: Improvement within the first week of inpatient rehabilitation is negatively correlated with subsequent functional change.
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| 11. |
- Denkinger, Michael D., et al.
(författare)
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Relationship Between Fear of Falling and Outcomes of an Inpatient Geriatric Rehabilitation Population : Fear of the Fear of Falling
- 2010
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Ingår i: Journal of The American Geriatrics Society. - : Wiley. - 0002-8614 .- 1532-5415. ; 58:4, s. 664-673
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES To examine the effects of various risk factors on three functional outcomes during rehabilitation. SETTING Geriatric inpatient rehabilitation unit. DESIGN Observational longitudinal study. PARTICIPANTS One hundred sixty-one geriatric rehabilitation inpatients (men, women), mean age 82, who were capable of walking at baseline. MEASUREMENTS Functional status was assessed weekly between admission and discharge and at a follow-up 4 months later at home using the function component of the Short Form-Late Life Function and Disability Instrument, the Barthel Index, and Habitual Gait Speed. Various risk factors, such as falls-related self-efficacy (Falls Efficacy Scale-International), were measured. Associations between predictors and functional status at discharge and follow-up were analyzed using linear regression models and bivariate plots. RESULTS Fear of falling predicted functioning across all outcomes except for habitual gait speed at discharge and follow-up. Visual comparison of functional trajectories between subgroups confirmed these findings, with different levels of fear of falling across time in linear plots. Thus, superior ability of this measure to discriminate between functional status at baseline across all outcomes and to discriminate between functional change especially with regard to the performance-based outcome was demonstrated. CONCLUSION Falls-related self-efficacy is the only parameter that significantly predicts rehabilitation outcome at discharge and follow-up across all outcomes. Therefore, it should be routinely assessed in future studies in (geriatric) rehabilitation and considered to be an important treatment goal.
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| 12. |
- Grandin, Magnus, 1981-
(författare)
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Adaptive Solvers for High-Dimensional PDE Problems on Clusters of Multicore Processors
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Accurate numerical solution of time-dependent, high-dimensional partial differential equations (PDEs) usually requires efficient numerical techniques and massive-scale parallel computing. In this thesis, we implement and evaluate discretization schemes suited for PDEs of higher dimensionality, focusing on high order of accuracy and low computational cost.Spatial discretization is particularly challenging in higher dimensions. The memory requirements for uniform grids quickly grow out of reach even on large-scale parallel computers. We utilize high-order discretization schemes and implement adaptive mesh refinement on structured hyperrectangular domains in order to reduce the required number of grid points and computational work. We allow for anisotropic (non-uniform) refinement by recursive bisection and show how to construct, manage and load balance such grids efficiently. In our numerical examples, we use finite difference schemes to discretize the PDEs. In the adaptive case we show how a stable discretization can be constructed using SBP-SAT operators. However, our adaptive mesh framework is general and other methods of discretization are viable.For integration in time, we implement exponential integrators based on the Lanczos/Arnoldi iterative schemes for eigenvalue approximations. Using adaptive time stepping and a truncated Magnus expansion, we attain high levels of accuracy in the solution at low computational cost. We further investigate alternative implementations of the Lanczos algorithm with reduced communication costs.As an example application problem, we have considered the time-dependent Schrödinger equation (TDSE). We present solvers and results for the solution of the TDSE on equidistant as well as adaptively refined Cartesian grids.
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| 13. |
- Lembrechts, Jonas J., et al.
(författare)
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Global maps of soil temperature
- 2022
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 28:9, s. 3110-3144
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Tidskriftsartikel (refereegranskat)abstract
- Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1-km2 resolution for 0–5 and 5–15cm soil depth. These maps were created by calculating the difference (i.e. offset) between in situ soil temperature measurements, based on time series from over 1200 1-km2 pixels (summarized from 8519 unique temperature sensors) across all the world's major terrestrial biomes, and coarse-grained air temperature estimates from ERA5-Land (an atmospheric reanalysis by the European Centre for Medium-Range Weather Forecasts). We show that mean annual soil temperature differs markedly from the corresponding gridded air temperature, by up to 10°C (mean=3.0±2.1°C), with substantial variation across biomes and seasons. Over the year, soils in cold and/or dry biomes are substantially warmer (+3.6±2.3°C) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler (−0.7±2.3°C). The observed substantial and biome-specific offsets emphasize that the projected impacts of climate and climate change on near-surface biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments. The global soil-related bioclimatic variables provided here are an important step forward for any application in ecology and related disciplines. Nevertheless, we highlight the need to fill remaining geographic gaps by collecting more in situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications.
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| 14. |
- Lembrechts, Jonas J., et al.
(författare)
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SoilTemp : A global database of near-surface temperature
- 2020
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 26:11, s. 6616-6629
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Tidskriftsartikel (refereegranskat)abstract
- Current analyses and predictions of spatially explicit patterns and processes in ecology most often rely on climate data interpolated from standardized weather stations. This interpolated climate data represents long-term average thermal conditions at coarse spatial resolutions only. Hence, many climate-forcing factors that operate at fine spatiotemporal resolutions are overlooked. This is particularly important in relation to effects of observation height (e.g. vegetation, snow and soil characteristics) and in habitats varying in their exposure to radiation, moisture and wind (e.g. topography, radiative forcing or cold-air pooling). Since organisms living close to the ground relate more strongly to these microclimatic conditions than to free-air temperatures, microclimatic ground and near-surface data are needed to provide realistic forecasts of the fate of such organisms under anthropogenic climate change, as well as of the functioning of the ecosystems they live in. To fill this critical gap, we highlight a call for temperature time series submissions to SoilTemp, a geospatial database initiative compiling soil and near-surface temperature data from all over the world. Currently, this database contains time series from 7,538 temperature sensors from 51 countries across all key biomes. The database will pave the way toward an improved global understanding of microclimate and bridge the gap between the available climate data and the climate at fine spatiotemporal resolutions relevant to most organisms and ecosystem processes.
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| 15. |
- Akter, Shaheda T., et al.
(författare)
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A numerical study of the stiffness and strength of cross-laminated timber wall-to-floor connections under compression perpendicular to the grain
- 2021
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Ingår i: Buildings. - : MDPI AG. - 2075-5309. ; 11:10
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Tidskriftsartikel (refereegranskat)abstract
- The use of cross-laminated timber (CLT) in multi-story buildings is increasing due to the potential of wood to reduce green house gas emissions and the high load-bearing capacity of CLT. Compression perpendicular to the grain (CPG) in CLT is an important design aspect, especially in multi-storied platform-type CLT buildings, where CPG stress develops in CLT floors due to loads from the roof or from upper floors. Here, CPG of CLT wall-to-floor connections are studied by means of finite element modeling with elasto-plastic material behavior based on a previously validated Quadratic multi-surface (QMS) failure criterion. Model predictions were first compared with experiments on CLT connections, before the model was used in a parameter study, to investigate the influence of wall and floor thicknesses, the annual ring pattern of the boards and the number of layers in the CLT elements. The finite element model agreed well with experimental findings. Connection stiffness was overestimated, while the strength was only slightly underestimated. The parameter study revealed that the wall thickness effect on the stiffness and strength of the connection was strongest for the practically most relevant wall thicknesses between 80 and about 160 mm. It also showed that an increasing floor thickness leads to higher stiffness and strength, due to the load dispersion effect. The increase was found to be stronger for smaller wall thicknesses. The influence of the annual ring orientation, or the pith location, was assessed as well and showed that boards cut closer to the pith yielded lower stiffness and strength. The findings of the parameter study were fitted with regression equations. Finally, a dimensionless ratio of the wall-to-floor thickness was used for deriving regression equations for stiffness and strength, as well as for load and stiffness increase factors, which could be used for the engineering design of CLT connections.
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| 16. |
- Antony, Jiju, et al.
(författare)
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Quality management as a means for micro-level sustainability development in organizations
- 2023
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Ingår i: The TQM Journal. - : Emerald Publishing. - 1754-2731 .- 1754-274X.
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: The use of quality management (QM) to achieve the United Nations Sustainable Development Goals (UNSDGs) is a topic of growing interest in academia and industry. The IAQ (International Academy for Quality) established Quality Sustainability Award in 2020, a testament to this growing interest. This study aims to investigate how QM philosophies, methodologies and tools can be used to achieve sustainable development in organizations. Design/methodology/approach: Five large manufacturing organizations – three from India and two from China – who reported their achievements about using QM in achieving Sustainable Development Goals (SDGs) were studied using multiple sources of data collection. A detailed within-case and cross-case analysis were conducted to unearth this linkage's practical and theoretical aspects. Findings: The study finds that QM methodologies effectively met the five organizations' UNSDGs. These organizations successfully used OPEX (Operational Excellence) methodologies such as Lean, Kaizen and Six Sigma to meet UNSDGs 7, 11, 12 and 13. Moreover, UNSG 12 (Responsible Consumption and Production) is the most targeted goal across the case studies. A cross-case analysis revealed that the most frequently used quality tools were Design of Experiments (DoE), Measurement Systems Analysis (MSA), C&E analysis and Inferential statistics, among other essential tools. Research limitations/implications: The study's sample size was limited to large-scale manufacturing organizations in the two most populous countries in the world. This may limit the study's generalizability to other countries, continents, or micro-, small- and medium-sized enterprises (SMEs). Additionally, the study's conclusions would be strengthened if tested as hypotheses in a follow-up survey. Practical implications: This practical paper provides case studies on how to use QM to impact SDGs. It offers both descriptive and prescriptive solutions for practitioners. The study highlights the importance of using essential QM tools in a structured and systematic manner, with effective teams, to meet the SDGs of organizations. Social implications: The study shows how QM can be used to impact UNSDGs, and this is very important because the UNSDGs are a set of global objectives that aim to address a wide range of social and environmental issues. This study could motivate organizations to achieve the UNSDGs using essential QM tools and make the world a better place for the present and future generations. Originality/value: This case study is the first to investigate at a micro-level how QM can impact UNSDGs using live examples. It uses data from the IAQ to demonstrate how QM can be integrated into UNSDGs to ensure sustainable manufacturing.
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| 17. |
- Anzt, Hartwig, et al.
(författare)
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An environment for sustainable research software in Germany and beyond: current state, open challenges, and call for action
- 2020
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Ingår i: F1000 Research. - : F1000 Research Ltd. - 2046-1402. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Research software has become a central asset in academic research. It optimizes existing and enables new research methods, implements and embeds research knowledge, and constitutes an essential research product in itself. Research software must be sustainable in order to understand, replicate, reproduce, and build upon existing research or conduct new research effectively. In other words, software must be available, discoverable, usable, and adaptable to new needs, both now and in the future. Research software therefore requires an environment that supports sustainability. Hence, a change is needed in the way research software development and maintenance are currently motivated, incentivized, funded, structurally and infrastructurally supported, and legally treated. Failing to do so will threaten the quality and validity of research. In this paper, we identify challenges for research software sustainability in Germany and beyond, in terms of motivation, selection, research software engineering personnel, funding, infrastructure, and legal aspects. Besides researchers, we specifically address political and academic decision-makers to increase awareness of the importance and needs of sustainable research software practices. In particular, we recommend strategies and measures to create an environment for sustainable research software, with the ultimate goal to ensure that software-driven research is valid, reproducible and sustainable, and that software is recognized as a first class citizen in research. This paper is the outcome of two workshops run in Germany in 2019, at deRSE19 - the first International Conference of Research Software Engineers in Germany - and a dedicated DFG-supported follow-up workshop in Berlin.
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| 18. |
- Bader, Dan, et al.
(författare)
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Laboratory measurement of the interface pressures applied by active therapy support surfaces : A consensus document
- 2010
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Ingår i: Journal of Tissue Viability. - : Elsevier BV. - 0965-206X. ; 19:1, s. 2-6
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Tidskriftsartikel (refereegranskat)abstract
- A key element in pressure ulcer prevention and management is the selection of appropriate pressure redistributing (PR) patient support surfaces for use while seated and in bed. However little explicit guidance exists allowing standardised quantitative comparison of different PR surfaces based upon their ability to redistribute pressure from anatomical landmarks such as the heels and sacrum. In 2008 a working group was established in Europe through the US National Pressure Ulcer Advisory Panel (NPUAP) support surface standardisation initiative (S3I) and under the aegis of the European Pressure Ulcer Advisory Panel with the specific remit of developing test methods for the evaluation of active therapy support surfaces (alternating pressure air mattresses). This report describes a consensus development process to agree test methods appropriate to compare active therapy surfaces based upon their ability to redistribute pressure from the sacrum and the heels.
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| 19. |
- Bader, I., et al.
(författare)
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Recruitment of pre-dementia participants: main enrollment barriers in a longitudinal amyloid-PET study
- 2023
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Ingår i: Alzheimer's Research & Therapy. - 1758-9193. ; 15:1
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Tidskriftsartikel (refereegranskat)abstract
- Background The mismatch between the limited availability versus the high demand of participants who are in the pre-dementia phase of Alzheimer's disease (AD) is a bottleneck for clinical studies in AD. Nevertheless, potential enrollment barriers in the pre-dementia population are relatively under-reported. In a large European longitudinal biomarker study (the AMYPAD-PNHS), we investigated main enrollment barriers in individuals with no or mild symptoms recruited from research and clinical parent cohorts (PCs) of ongoing observational studies.Methods Logistic regression was used to predict study refusal based on sex, age, education, global cognition (MMSE), family history of dementia, and number of prior study visits. Study refusal rates and categorized enrollment barriers were compared between PCs using chi-squared tests.Results 535/1856 (28.8%) of the participants recruited from ongoing studies declined participation in the AMYPAD-PNHS. Only for participants recruited from clinical PCs (n = 243), a higher MMSE-score (beta = - 0.22, OR = 0.80, p < .05), more prior study visits (beta = - 0.93, OR = 0.40, p < .001), and positive family history of dementia (beta = 2.08, OR = 8.02, p < .01) resulted in lower odds on study refusal. General study burden was the main enrollment barrier (36.1%), followed by amyloid-PET related burden (PCresearch = 27.4%, PCclinical = 9.0%, X-2 = 10.56, p = .001), and loss of research interest (PCclinical = 46.3%, PCresearch = 16.5%, X-2 = 32.34, p < .001).Conclusions The enrollment rate for the AMYPAD-PNHS was relatively high, suggesting an advantage of recruitment via ongoing studies. In this observational cohort, study burden reduction and tailored strategies may potentially improve participant enrollment into trial readiness cohorts such as for phase-3 early anti-amyloid intervention trials. The AMYPAD-PNHS (EudraCT: 2018-002277-22) was approved by the ethical review board of the VU Medical Center (VUmc) as the Sponsor site and in every affiliated site.
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| 20. |
- Bader, Thomas K., 1980-, et al.
(författare)
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Berechnungsmodell für das Last-Verformungsverhalten von Stabdübelgruppen im Ingenieurholzbau
- 2014
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Ingår i: Berichte der Fachtagung Baustatik-Baupraxis 12. - München : Technischen Universität, München. - 9783000412561 ; , s. 113-121
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In diesem Beitrag wird ein Berechnungsmodell für das Last-Verformungsverhalten von Stabdübelgruppen vorgestellt, mit dem lokale Verbindungsmittelkräfte und Verbindungsmitteldeformationen mit zugehörigen globale Schnittgrößen und Relativverformungen konsistent berechnet werden können. Grundlage dafür bildet das Last-Verformungsverhalten des Einzeldübels, das mit Hilfe eines baustatischen Modellierungsansatzes hergeleitet wird. Ein wesentlicher Eingangsparameter dieses Modells ist die Lochleibungsfestigkeit von Holz, die für beliebige Kraft-Faserrichtungen experimentell untersucht wurde. Mit Hilfe des vorgestellten Berechnungsmodells für Stabdübelgruppen können die Tragfähigkeit einer Verbindung unter einer beliebigen Kombination von Normalkraft, Querkraft und Momentenbeanspruchung und die zugehörige Relativverformung berechnet werden. Mit dem vorgestellten Berechnungsmodell kann der lastfallabhängige Einfluss einer Verbindung auf Schnittgrößen-Verformungsinteraktionen direkt in der baustatischen Berechnung von Holzkonstruktionen berücksichtigt werden.
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| 21. |
- Bader, Thomas K., 1980-, et al.
(författare)
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Engineering design for anefficient assembly of multi-storycross-laminated timber structures : A survey conducted between November 2020 and November 2021
- 2023
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Design for efficient assembly is essential to further enhance the competitiveness of cross-laminated timber building systems for multi-story timber structures. This requires a holistic view from the design of the load bearing structures by structural engineers, over the production, pre-fabrication, and transport to the assembly of the structural elements on-site, which often is done by different companies with input from different stakeholders in the construction process. Especially the design of connections between CLT elements, and CLT and other construction materials and products, as well as the size of CLT elements and possibilities for pre-fabrication are crucial for an efficient assembly process. The paper summarizes findings from expert interviews with a focus on Sweden along the before-mentioned value chain, with the aim to identify current practice and potentials for further improvements. Design for efficient assembly starts at the early-stage design and involves all stakeholders in the design construction process. The reduction of uncertainties in the design and assembly process of multi-storey CLT structures as well as knowledge and experience transfer could lead to more efficient design. The identified requirements for efficient assembly should be combined with a life cycle analysis to quantify the potential for a reduction of the carbon footprint of CLT-based building systems, which is the aim of the ongoing research project ‘Improving the competitive advantage of CLT-based building systems through engineering design and reduced carbon footprint’.
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| 22. |
- Bader, Thomas K., 1980-, et al.
(författare)
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Ingenieurmodelle für die Strukturmodellierung und Nachweisführung von stiftförmigen Verbindungen im Holzbau : (Engineering models for the structural design and verification of dowel-type connections in timber structures)
- 2017
-
Ingår i: Österreichische Ingenieur- und Architekten-Zeitschrift. - : Oesterreichischen Ingenieur- und Architekten-Vereines. - 0721-9415. ; 162:1-12, s. 1-9
-
Tidskriftsartikel (refereegranskat)abstract
- Connections of elements in timber structures play an important role, not only due to their pronounced effect on the mechanical behavior of structures, but also due to the fact they can be decisive for the economic success of timber structures. Herein, approaches for a calculation of the ductile load-displacement behavior of dowel-type connections, of multi-dowel joints and of stresses in their timber matrix, by means of numerical methods, are presented. With these methods, kinematically compatible relative deformations of joints under arbitrary plane loading conditions and their effect on the mechanical behavior of timber structures can be reasonably predicted. The combination of the presented models and their integration in the structural analysis and the verification of timber structures lead to a more realistic prediction of their behavior (internal forces, stresses and deformations), as well as to a more economic design of timber structures.
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| 23. |
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| 24. |
- Bader, Thomas K., 1980-, et al.
(författare)
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Load Distribution in Multi-Dowel Timber Connections under Moment Loading : Integrative Evaluation of Multiscale Experiments
- 2016
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Ingår i: Proceedings of the 2016 World Conference on Timber Engineering (WCTE). - Vienna : Vienna University of Technology. - 9783903039001
-
Konferensbidrag (refereegranskat)abstract
- The load distribution in multi-dowel timber connections under bending moments was investigated by means of an integrative evaluation of a hierarchically organized test program, which encompassed component tests as well as single dowel and multi-dowel connection tests. It was demonstrated that the anisotropic material behaviour of LVL, and consequently of wood in general, leads to a non-uniform distribution among the dowels.
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| 25. |
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| 26. |
- Bader, Thomas K., 1980-, et al.
(författare)
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Numerical modeling of the load distribution in multiple fastener joints
- 2017
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Ingår i: International Conference on Connections in Timber Engineering – From Research to Standards. - Graz : Verlag der Technischen Universität Graz. - 9783851255539 ; , s. 136-152
-
Konferensbidrag (refereegranskat)abstract
- Numerical modeling approaches, for the determination of load distribution in laterally loaded joints, as well as for the assignment of stiffness properties of joints for the structural analysis, are summarized in this contribution. The effect of the nonlinearity and the load-to-grain orientation dependence of connection slip, of elastic deformation in the surrounding wood matrix, and of the deviation between load and displacement direction are discussed. Comparison of various models demonstrates the pronounced effect of the load-to-grain orientation dependence and the nonlinearity in connection slip on the load distribution, particularly in case of moment loading. The effect of elastic deformation in the wood matrix on the load distribution increases with increased size of joints, even more pronounced when joints are loaded by a shear force perpendicular to the grain. In case of normal force loading, the non-uniform load distribution due to elastic deformation in the wood matrix reduces rapidly with increased relative joint displacement. Pros and cons of the modeling approaches as well as necessary input data are discussed in relation to the design process and European standardization.
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| 27. |
- Bader, Thomas K., 1980-, et al.
(författare)
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Numerical modelling of the rope effect in laterally loaded dowel-type connections
- 2018
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Ingår i: 6<sup>th</sup> European Conference on Computational Mechanics (ECCM 6), 7<sup>th</sup> European Conference on Computational Fluid Dynamics (ECFD 7), 11 – 15 June 2018, Glasgow, UK.
-
Konferensbidrag (refereegranskat)abstract
- Theory of laterally loaded dowel-type fasteners is well understood in relation to their bending deformation as a consequence of lateral embedment stresses in wood. Modelling of the so- called rope effect has however attracted less attention. The rope effect in laterally loaded connections is evoked by withdrawal resistance of the shank as well as by axial resistance of the head of the fasteners. It describes the development of tensile forces along the axis of the fastener, as a consequence of its bending deformation and axial constrains. Hilson [1] emphasized the pronounced contribution of frictional forces in the shear planes that contribute to increased strength of laterally loaded connections. The axial force component parallel to the shear plane however will only become significant for large relative displacements. Different kind of numerical models have been proposed for the simulation of dowel-type connections, including 3D FEM with elasto-plastic material models, with damage mechanics, or so-called foundation models. In this contribution, calculations with a beam-on-nonlinear foundation method [2] will be presented. The model was extended to account for increased lateral connection strength due to withdrawal resistance of fasteners. This was implemented in terms of axial springs that encompass a withdrawal force-relative displacement relationship, similar to the lateral springs that hold information on the embedment behaviour. Friction between the connected timber members was taken into account by the frictional coefficient times the force component perpendicular to the shear plane, which is a result of the axial force in the fastener.Calculations were performed for different types of dowel-type fasteners, including screws, smooth shank nails, annular-ringed shank nails and smooth dowels. Model predictions were compared to experimental data and showed good agreement. This encourages the use of the beam model for the engineering design of dowel-type connections in timber structures based on a deeper understanding of structure-connection relationships [3].
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| 28. |
- Bader, Thomas K., 1980-, et al.
(författare)
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The Historical Roof Structure of the Leopold Wing of the Vienna Hofburg Palace : Structural Assessment
- 2015
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Ingår i: Proceedings of the International Conference on Structural Health Assessment of Timber Structures (SHATIS'15). - 9788371252563
-
Konferensbidrag (refereegranskat)abstract
- In this case study, the structural behaviour of the historic roof structure of the “Leopold Wing”, part of the Hofburg, the Vienna Imperial Palace, is assessed. The current appearance of the roof is a consequence of several adaptions and extensions of the original structure that dates back to the 17th century. The main part of the roof was reconstructed in the early 1670s following a disastrous fire in February 1668. The structure had the shape of an M-roof consisting of two adjacent gable roofs. Probably in the 19th century, the centre part was closed, creating a mansard roof over the entire width of the building. Basically, the geometry of the structure is symmetric with respect to the middle wall. However, since the position of the middle wall is partly asymmetric, also the roof structure becomes asymmetric. Herein, the influence of the building history on the load-deformation behaviour of the roof structure is investigated. Therefore, structural analyses of the original M-roof and of the mansard roof are performed. The modelling of the historic roof structure is based on a deformation-accurate survey. In addition, the influence of the nonlinear, compliant behaviour of connections on the load-deformation behaviour of the timber structure is taken into account. A considerable influence of the connection slip on the deformation of the structure becomes obvious from the analysis. Consequently, consideration of the nonlinear behaviour of the joints reveals a realistic load transfer within the structure. The addition of structural elements caused additional dead loads, which increase long-term deformations.
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| 29. |
- Basterrechea-Arevalo, M., et al.
(författare)
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Numerical modelling of moment-transmitting timber connections
- 2023
-
Ingår i: Engineering structures. - : Elsevier. - 0141-0296 .- 1873-7323. ; 297
-
Tidskriftsartikel (refereegranskat)abstract
- In recent years, the use of timber in construction substantially increased due to the material's renewable nature, lower climate impact and increased economic competitiveness. Another driving factor is great improvements in modelling techniques for the design of timber structures. Suitable prediction of the connection behaviour, as a fundamental part of the structural behaviour of timber structures, is crucial for a more economic and reliable design. However, the more realistic and complete connection models, the more complex and difficult to handle they are, which might hinder their practical application. A good trade-off between complexity and computational efficiency can be achieved with the so-called Beam-On-Foundation (BOF) method, which is applied herein in a 2-step hierarchical model to analyse and predict the rotational stiffness, ductile capacity and load distribution among fasteners of four different configurations of moment transmitting beam-to-column timber-to-timber connections. The connection model is validated with experiments on the global response of the connection as well as with a 3-D solid FEM model. The herein proposed connection model well predicted the overall connection response and provided insight into the local fastener behaviour. As compared to the 3-D solid model, which additionally gives access to more realistic local stresses in the timber, the 2-step model is however much more efficient with a great reduction of computation time. This makes the approach suitable for parametric studies and the analysis and engineering design of timber structures.
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| 30. |
- Bekassy, Zivile, et al.
(författare)
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Crosstalk between the renin–angiotensin, complement and kallikrein–kinin systems in inflammation
- 2022
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Ingår i: Nature Reviews Immunology. - : Springer Science and Business Media LLC. - 1474-1733 .- 1474-1741. ; 22:7, s. 411-428
-
Forskningsöversikt (refereegranskat)abstract
- During severe inflammatory and infectious diseases, various mediators modulate the equilibrium of vascular tone, inflammation, coagulation and thrombosis. This Review describes the interactive roles of the renin–angiotensin system, the complement system, and the closely linked kallikrein–kinin and contact systems in cell biological functions such as vascular tone and leakage, inflammation, chemotaxis, thrombosis and cell proliferation. Specific attention is given to the role of these systems in systemic inflammation in the vasculature and tissues during hereditary angioedema, cardiovascular and renal glomerular disease, vasculitides and COVID-19. Moreover, we discuss the therapeutic implications of these complex interactions, given that modulation of one system may affect the other systems, with beneficial or deleterious consequences.
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| 31. |
- Collij, L. E., et al.
(författare)
-
The amyloid imaging for the prevention of Alzheimer's disease consortium: A European collaboration with global impact
- 2023
-
Ingår i: Frontiers in Neurology. - : Frontiers Media SA. - 1664-2295. ; 13
-
Tidskriftsartikel (refereegranskat)abstract
- BackgroundAmyloid-beta (A beta) accumulation is considered the earliest pathological change in Alzheimer's disease (AD). The Amyloid Imaging to Prevent Alzheimer's Disease (AMYPAD) consortium is a collaborative European framework across European Federation of Pharmaceutical Industries Associations (EFPIA), academic, and 'Small and Medium-sized enterprises' (SME) partners aiming to provide evidence on the clinical utility and cost-effectiveness of Positron Emission Tomography (PET) imaging in diagnostic work-up of AD and to support clinical trial design by developing optimal quantitative methodology in an early AD population. The AMYPAD studiesIn the Diagnostic and Patient Management Study (DPMS), 844 participants from eight centres across three clinical subgroups (245 subjective cognitive decline, 342 mild cognitive impairment, and 258 dementia) were included. The Prognostic and Natural History Study (PNHS) recruited pre-dementia subjects across 11 European parent cohorts (PCs). Approximately 1600 unique subjects with historical and prospective data were collected within this study. PET acquisition with [F-18]flutemetamol or [F-18]florbetaben radiotracers was performed and quantified using the Centiloid (CL) method. ResultsAMYPAD has significantly contributed to the AD field by furthering our understanding of amyloid deposition in the brain and the optimal methodology to measure this process. Main contributions so far include the validation of the dual-time window acquisition protocol to derive the fully quantitative non-displaceable binding potential (BPND), assess the value of this metric in the context of clinical trials, improve PET-sensitivity to emerging A beta burden and utilize its available regional information, establish the quantitative accuracy of the Centiloid method across tracers and support implementation of quantitative amyloid-PET measures in the clinical routine. Future stepsThe AMYPAD consortium has succeeded in recruiting and following a large number of prospective subjects and setting up a collaborative framework to integrate data across European PCs. Efforts are currently ongoing in collaboration with ARIDHIA and ADDI to harmonize, integrate, and curate all available clinical data from the PNHS PCs, which will become openly accessible to the wider scientific community.
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| 32. |
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| 33. |
- Dodoo, Ambrose, 1979-, et al.
(författare)
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Exploring the synergy between structural engineering design solutions and life cycle carbon footprint of cross-laminated timber in multi-storey buildings
- 2022
-
Ingår i: Wood Material Science & Engineering. - : Taylor & Francis Group. - 1748-0272 .- 1748-0280. ; 17:1, s. 30-42
-
Tidskriftsartikel (refereegranskat)abstract
- Low-carbon buildings and construction products can play a key role in creating a low-carbon society. Cross-laminated timber (CLT) is proposed as a prime example of innovative building products, revolutionising the use of timber in multi-storey construction. Therefore, an understanding of the synergy between structural engineering design solutions and climate impact of CLT is essential. In this study, the carbon footprint of a CLT multi-storey building is analysed in a life cycle perspective and strategies to optimise this are explored through a synergy approach, which integrates knowledge from optimised CLT utilisation, connections in CLT assemblies, risk management in building service-life and life cycle analysis. The study is based on emerging results in a multi-disciplinary research project to improve the competitiveness of CLT-based building systems through optimised structural engineering design and reduced climate impact. The impacts associated with material production, construction, service-life and end-of-life stages are analysed using a process-based life cycle analysis approach. The consequences of CLT panels and connection configurations are explored in the production and construction stages, the implications of plausible replacement scenarios are analysed during the service-life stage, and in the end-of-life stage the impacts of connection configuration for post-use material recovery and carbon footprint are analysed. The analyses show that a reduction of up to 43% in the life cycle carbon footprint can be achieved when employing the synergy approach. This study demonstrates the significance of the synergy between structural engineering design solutions and carbon footprint in CLT buildings.
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| 34. |
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| 35. |
- Dorn, Michael, 1978-, et al.
(författare)
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Non-Linear Connection Models in Timber Engineering
- 2016
-
Ingår i: Proceedings of the 2016 World Conference on Timber Engineering (WCTE). - Vienna : Vienna University of Technology. - 9783903039001
-
Konferensbidrag (refereegranskat)abstract
- In this contribution, a numerical model for connections in engineered timber structures, using specially designed connection elements, is presented. The model considers the non-linear load-displacement relation typical for many types of connections on different levels and is presented on the example of dowel-type connections. The structural levels investigated herein are a) the embedment behaviour of a dowel into wood; b) the behaviour of a singledowel connection; and c) a multi-dowel connection under a general load case typical for structural applications. A special characteristic considered in the formulation of the connector elements is the unloading behaviour, which is characterized by an initial high unloading stiffness but a very low stiffness when the load is fully removed. The latter is due to remaining permanent deformations in the wood as well as in the metal connector. The modelling approach was found to correlate well with experimental data and gave new insight in the behaviour of dowel connections, particularly as regards the unloading and reloading behaviour with alternating load directions on the single-dowel connection scale.
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| 36. |
- Dorn, Michael, 1978-, et al.
(författare)
-
Numerical Simulations of the Loading Process of Dowel-Type Timber Connections
- 2012
-
Ingår i: CD-ROM Proceedings of the 6th European Congress on Computational Methods in Applied Sciences and Engineering (ECCOMAS 2012). - : Vienna University of Technology. - 9783950248197
-
Konferensbidrag (refereegranskat)abstract
- In order to maximize utilization, numerical simulations are gaining importance in the design of timber structures. Dowel-type steel-to-timber connections are commonly used for a wide variety of loads. The current design generation, namely the Eurocode (EC)5 [1], is based on empirical tests, and lacks in many aspects a stringent mechanical foundation. The optimization of connections plays an important role for the competitiveness of timber structures, which is often restricted due to the inabilityof the design concepts to capture the large variety of fields of applications. The mechanical behavior of these types of connections is mainly driven by stiffness differences between the steel dowel and the wood part, whereby the strength properties of the materials and the geometric layout of the connection considerable affect the connection’s stiffness and strength.
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| 37. |
- Duru, Kenneth, et al.
(författare)
-
A stable discontinuous Galerkin method for the perfectly matched layer for elastodynamics in first order form
- 2020
-
Ingår i: Numerische Mathematik. - : Springer Science and Business Media LLC. - 0029-599X .- 0945-3245. ; 146:4, s. 729-782
-
Tidskriftsartikel (refereegranskat)abstract
- We present a stable discontinuous Galerkin (DG) method with a perfectly matched layer (PML) for three and two space dimensional linear elastodynamics, in velocity-stress formulation, subject to well-posed linear boundary conditions. First, we consider the elastodynamics equation, in a cuboidal domain, and derive an unsplit PML truncating the domain using complex coordinate stretching. The hyperbolic structure of the underlying system enables the construction of continuous energy estimates, in the time domain for the elastic wave equation, and in the Laplace space for a sequence of PML model problems, with variations in one, two and three space dimensions, respectively. They correspond to PMLs normal to boundary faces, along edges and in corners. Second, we develop a DG numerical method for the linear elastodynamics equation using physically motivated numerical flux and penalty parameters, which are compatible with all well-posed, internal and external, boundary conditions. When the PML damping vanishes in all directions, by construction, our choice of penalty parameters yield an upwind scheme and a discrete energy estimate analogous to the continuous energy estimate. Third, to ensure numerical stability of the discretization when PML damping is present, it is necessary to extend the numerical DG fluxes, and the numerical inter-element and boundary procedures, to the PML auxiliary differential equations. This is crucial for deriving discrete energy estimates analogous to the continuous energy estimates. Numerical solutions are evolved in time using the high order arbitrary derivative (ADER) time stepping scheme of the same order of accuracy with the spatial discretization. By combining the DG spatial approximation with the high order ADER time stepping scheme and the accuracy of the PML we obtain an arbitrarily high-order accurate wave propagation solver in the time domain. Numerical experiments are presented in two and three space dimensions corroborating the theoretical results.
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| 38. |
- Gikonyo, Joan, et al.
(författare)
-
A spring model for prediction of the nonlinear embedment load-displacement behaviour of dowel-type fasteners in cross-laminated timber
- 2021
-
Ingår i: World Conference on Timber Engineering 2021, WCTE 2021. - : World Conference on Timber Engineering (WCTE).
-
Konferensbidrag (refereegranskat)abstract
- The embedment strength for design of connections in cross-laminated timber (CLT) structures is usually based on an extensive experimental study. In the research presented herein, a spring model is presented that takes into consideration the embedment properties of each layer to predict strength and stiffness of the nonlinear embedment behaviour of dowels in CLT. To gain input data for the spring model, experimental load-displacement data for various timber products, namely glulam, structural timber and laminated veneer lumber (LVL), were analysed. A nonlinear embedment ratio, defined as the embedment stress parallel to the grain with respect to the embedment stress perpendicular to the grain, was derived. Thereafter, this embedment ratio was used to back-calculate the embedment stress-displacement behaviour of single layers in CLT. The back-calculated embedment stress for single layers loaded parallel and perpendicular to the grain was then compared to embedment stress of glued laminated timber and to the Eurocode 5 equations. A good correlation was found for CLT with common layer thicknesses of higher than 20 mm, while for CLT with smaller layer thicknesses a considerable overestimation of the embedment stress was observed. This might be explained by reinforcement and strengthening effects in the interface between the layers, which gets more evident in CLT with small layer thickness. From the study it was evident that it is possible to predict the embedment behaviour of CLT by application of the herein proposed spring model to CLT with common layer thickness. Furthermore, the potential of the spring model for an enhanced design of CLT connections, by consideration of the CLT layup, was demonstrated in a parametric study. © WCTE 2021. All rights reserved.
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| 39. |
- Gikonyo, Joan, et al.
(författare)
-
Beam-on-Foundation modelling of dowel-type single fastener connections in cross laminated timber
- 2024
-
Ingår i: Engineering structures. - : Elsevier. - 0141-0296 .- 1873-7323. ; 303
-
Tidskriftsartikel (refereegranskat)abstract
- In this study, a numerical model that aimed to predict the strength and stiffness, of a single laterally loaded mechanical fastener in steel-to-cross laminated timber (CLT) connections using a Beam-on-Foundation (BoF) model, is presented. The BoF model was used to predict the ductile failure modes of steel-to-CLT connections and considered the layered structure of CLT. When compared to the European Yield Model (EYM), the BoF model was found to be advantageous as it not only predicted the strength but also the stiffness of the connections. A comparison of the slip modulus and strength from BoF model simulations of experimental tests carried out on steel-to-CLT connections showed good agreement with the experimental results. Using the BoF model, the influence of; (i) density, (ii) deck layer orientation, (iii) embedment behaviour, (iv) dowel diameter, (v) steel plate thickness, and (vi) embedment length, on steel-to-CLT connections was investigated in a parameter study. The results presented herein highlight the benefit of the BoF model that considers CLT layer specific embedment behaviour in determining the shear capacity and stiffness of steel-to-CLT connections.
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| 40. |
- Gikonyo, Joan, et al.
(författare)
-
Exploring the relationship between embedment behaviour in cross-laminated timber and its layers: An experimental study
- 2024
-
Ingår i: Engineering Structures. - 0141-0296. ; 318
-
Tidskriftsartikel (refereegranskat)abstract
- Cross-laminated timber (CLT) has become popular as a construction material and the design of CLT connections is typically based on empirical equations with an average embedment strength of the wood-based product. The experimental study presented herein aims at enhancing the understanding of the relationship between the CLT embedment behaviour and the single layers it is composed of. Non-linear embedment stress–displacement relationships were measured in 244 full-hole and half-hole embedment tests on structural timber boards as well as on CLT produced of parts of the same boards. Three different fasteners, namely a steel dowel with a diameter of 12 mm and the threaded part of screws with a nominal diameter of 6.5 mm and 10 mm, were studied. The design of the experiments allowed to validate a simple mechanical model with parallel springs for the CLT, which showed good agreement with experiments. In addition to a validation of the non-linear spring model, this unique experimental data-set is further exploited in a comparison with empirical equations and for the derivation of a non-linear embedment ratio, between parallel and perpendicular to the grain embedment stresses, over the displacement. Knowledge of the relationship between the non-linear embedment behaviour of the single layers and the CLT element can be further exploited in the engineering design and numerical modelling of CLT connections with dowel-type fasteners.
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| 41. |
- Gikonyo, Joan, et al.
(författare)
-
Numerical Modelling of a Cross-Laminated Timber-to-Concrete Dowel-Type Connection Using the Beam-on-Foundation Model
- 2023
-
Ingår i: Proceedings from the 13th World Conference on Timber Engineering 2023. - Oslo, Norway : World Conference on Timber Engineering (WCTE). - 9781713873297 - 9781713873273 ; , s. 3101-3110
-
Konferensbidrag (refereegranskat)abstract
- The aim of the research presented herein is to investigate the mechanical behaviour of cross-laminated timber (CLT)-to-concrete dowel-type connections. For reliable timber-concrete-composite structures, mechanical connections between the two construction materials are of great importance. This paper investigates the nonlinear load-displacement behaviour, giving access to the stiffness and strength, as well as ductile connection failure modes, of a CLT-to-concrete composite connection using a Beam-on-Foundation (BoF) model. The latter is a numerical model that utilizes non-linear springs for the interaction between the fastener and the surrounding CLT and concrete materials. The influence of: (i) fastener diameter, (ii) initial slip, (iii) concrete embedment properties, and (iv) axial fastener resistance due to friction, on the connection shear capacity and slip modulus, was investigated in a parameter study. The nonlinear load-displacement response, connection stiffness and strength predicted by the BoF model were moreover compared to laboratory tests and the European Yield Model (EYM), which supported the validity of the BoF model. In addition, it was shown that the BoF model could enhance the prediction of the slip modulus compared to the current design regulations in Eurocode 5.
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| 42. |
- Hochreiner, Georg, et al.
(författare)
-
Matrix Failure of Multi-Dowel Type Connections Engineering Modelling and Parameter Study
- 2016
-
Ingår i: Proceedings of the 2016 World Conference on Timber Engineering (WCTE). - Vienna : Vienna University of Technology. - 9783903039001
-
Konferensbidrag (refereegranskat)abstract
- A simplified numerical engineering model for the design of the surrounding timber matrix of dowel groups, developed within the framework of a commercial structural analysis software, is presented herein. This model was applied to highlight and reflect various dowel arrangements in timber to steel connections from building practice subjected to arbitrary sets of internal forces against the background of both the real mechanical behavior and the present practice of design. A parameter study revealed the interdependence of stresses in the timber matrix and geometrical and mechanical properties of dowel groups.
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| 43. |
- Hochreiner, Georg, et al.
(författare)
-
Structural behaviour and design of dowel groups : experimental and numerical identification of stress states and failure mechanisms of the surrounding timber matrix
- 2017
-
Ingår i: Engineering structures. - : Elsevier. - 0141-0296 .- 1873-7323. ; 131, s. 421-437
-
Tidskriftsartikel (refereegranskat)abstract
- Dowel-type fasteners in combination with steel plates are widely used in engineered timber structures. Since dowel groups are designed as semi-rigid connections subjected to an arbitrary set of internal forces, the corresponding structural behaviour of the surrounding timber matrix must be considered in the design process accordingly, including the effect of reinforcements. Corresponding stress states and failure mechanisms in the timber matrix of dowel groups are discussed herein. Surface strain fields from tests of dowel groups under complex loading situations were used to identify the sequence of cracking, as well as to assign the related failure modes. First cracking events were caused by stress peaks at the most loaded dowels and by a combination of shear stresses and stresses perpendicular to the grain, while later crack- ing events were associated with a predominant action of individual stress components. Thus, the non- linear global moment-relative rotation behaviour of dowel groups could be related to failure mechanisms in the surrounding timber matrix. The corresponding strain state was qualitatively as well as quantita- tively reproduced by means of a numerical model, which gave access to stresses in the timber matrix and has potential to be implemented as a sub-model in engineering design software. The numerical model supported the feasibility of a decomposition of the stress state due to the global bending moment into stresses caused by a couple of equal forces parallel and perpendicular to the grain, which could be used in the design process. Based on experimental and numerical findings, essential aspects for a design procedure for the timber matrix in dowel groups loaded by a combination of internal forces are proposed.
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| 44. |
- Hochreiner, Georg, et al.
(författare)
-
The Historic Roof Structure of the Spanish Riding School in Vienna : Structural Assessment
- 2015
-
Ingår i: Proceedings of the International Conference on Structural Health Assessment of Timber Structures, SHATIS15. - : Dolnoslaskie Wydawnictwo Edukacyjne (DWE). - 9788371252563 ; , s. 248-259
-
Konferensbidrag (refereegranskat)abstract
- In 2012, the historical roof structure of the Spanish Riding School, built in the years from 1729 to 1735 as part of the ensemble of the Vienna Imperial Palace (called Hofburg), was documented by students and staff of the Vienna University of Technology. The survey was performed deformation- accurate and included both, the main structure and corresponding joints. Consequently, the documentation highlights deviations from the initial perception of the roof structure such as broken joints, inactivity of compressive devices like knee braces or excessive displacements of single structural members. Probably, these damages led to strengthening measures (=additional substructures) that were added in recent times to avoid progressive failure. This documentation formed the basis for the assessment of this historical roof structure from a structural and timber engineering point of view, which will be presented herein. The focus of the structural modelling was placed on the assessment of the two initial structural concepts, namely the main hall with and without the timber dome structure that was added in 1734, by visualisation of the internal forces and displacements. For this purpose, the nonlinear load carrying capacities and failure modes of the carpentry joints were assessed. Subsequently, alternative structural systems could be found by iterative recalculation revealing the capabilities for redundancy of the timber roof structure. Corresponding results were checked again with in-situ observations. Consequently, the findings of this study highlight the benefits of integrating modern structural and timber engineering methods and tools in the context of building history and building survey.
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| 45. |
- Hochreiner, Georg, et al.
(författare)
-
Timber Matrix Failure Modes in Multi-Dowel Connections
- 2016
-
Ingår i: 17th International Conference on Experimental Mechanics, Rhodes, Greece, July 3-7, 2016.
-
Konferensbidrag (populärvet., debatt m.m.)abstract
- The engineering design of dowel type steel-to-timber connections is comprehensive and shall also include the surrounding timber matrix, as required by the principles specified in Eurocode 5. As one part of a hierarchically structured research program, the loading and failure modes of multi-dowel connections has been investigated, including both the elastic as well as the cracked domain of the load history. Depending on the presence of local reinforcement, in order to prevent premature brittle failure and to insure local ductile dowel behavior, the global response became more or less ductile. The monitoring of surface deformations of the timber by means of a contact free displacement measurement system (DIC) supported the identification of stepwise changing structural systems. This data constitutes a valuable basement for the completion resp. improvement of the present design procedures with respect to consistency and effectiveness.
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| 46. |
- Hofstetter, Karin, et al.
(författare)
-
The Benefit of Micromechanical Modeling in Timber Engineering
- 2010
-
Ingår i: Proceedings of the 11th World Conference on Timber Engineering, June 20-24, 2010, Riva del Garda, Italy.
-
Konferensbidrag (refereegranskat)abstract
- Due to its highly optimized structure across several length scales, wood exhibits a very complex mechanical behavior at the macroscale and a high variability of its material properties. Both constitute major obstacles to a broader application of this material for engineering purposes. The combination of multiscale modeling and powerful material models implemented in numerical simulation software such as the finite element method is considered as efficient strategy to overcome these limitations and to improve reliability and capabilities of current timber engineering design. Examples of such models and their application to numerical analysis of a dowel joint are shown in this paper.
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| 47. |
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| 48. |
- Kahn, Robin, et al.
(författare)
-
Neutrophil-derived proteinase 3 induces kallikrein-independent release of a novel vasoactive kinin.
- 2009
-
Ingår i: Journal of immunology. - : The American Association of Immunologists. - 1550-6606 .- 0022-1767. ; 182:12, s. 7906-7915
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Tidskriftsartikel (refereegranskat)abstract
- The kinin-forming pathway is activated on endothelial cells and neutrophils when high-molecular weight kininogen (HK) is cleaved by plasma kallikrein liberating bradykinin, a potent mediator of inflammation. Kinins are released during inflammatory conditions such as vasculitis, associated with neutrophil influx around blood vessels. Some patients with vasculitis have elevated plasma levels of neutrophil-derived proteinase 3 (PR3) and anti-PR3 Abs. This study investigated if neutrophil-derived PR3 could induce activation of the kinin pathway. PR3 incubated with HK, or a synthetic peptide derived from HK, induced breakdown and release of a novel tridecapeptide termed PR3-kinin, NH(2)-MKRPPGFSPFRSS-COOH, consisting of bradykinin with two additional amino acids on each terminus. The reaction was specific and inhibited by anti-PR3 and alpha(1)-antitrypsin. Recombinant wild-type PR3 incubated with HK induced HK breakdown, whereas mutated PR3, lacking enzymatic activity, did not. PR3-kinin bound to and activated human kinin B(1) receptors, but did not bind to B(2) receptors, expressed by transfected HEK293 cells in vitro. In human plasma PR3-kinin was further processed to the B(2) receptor agonist bradykinin. PR3-kinin exerted a hypotensive effect in vivo through both B(1) and B(2) receptors as demonstrated using wild-type and B(1) overexpressing rats as well as wild-type and B(2) receptor knockout mice. Neutrophil extracts from vasculitis patients and healthy controls contained comparable amounts of PR3 and induced HK proteolysis, an effect that was abolished when PR3 was immunoadsorbed. Neutrophil-derived PR3 can proteolyze HK and liberate PR3-kinin, thereby initiating kallikrein-independent activation of the kinin pathway.
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| 49. |
- Lankester, Arjan C, et al.
(författare)
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Hematopoietic cell transplantation in severe combined immunodeficiency: The SCETIDE 2006-2014 European cohort.
- 2022
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Ingår i: The Journal of allergy and clinical immunology. - : Elsevier BV. - 1097-6825 .- 0091-6749. ; 149:5
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Tidskriftsartikel (refereegranskat)abstract
- Hematopoietic stem cell transplantation (HSCT) represents a curative treatment for patients with severe combined immunodeficiency (SCID), a group of monogenic immune disorders with an otherwise fatal outcome.We performed a comprehensive multicenter analysis of genotype-specific HSCT outcome, including detailed analysis of immune reconstitution (IR) and the predictive value for clinical outcome.HSCT outcome was studied in 338 patients with genetically confirmed SCID who underwent transplantation in 2006-2014 and who were registered in the SCETIDE registry. In a representative subgroup of 152 patients, data on IR and long-term clinical outcome were analyzed.Two-year OS was similar with matched family and unrelated donors and better than mismatched donor HSCT (P<.001). The 2-year event-free survival (EFS) was similar in matched and mismatched unrelated donor and less favorable in mismatched related donor (MMRD) HSCT (P< .001). Genetic subgroups did not differ in 2-year OS (P= .1) and EFS (P=.073). In multivariate analysis, pretransplantation infections and use of MMRDs were associated with less favorable OS and EFS. With a median follow-up of 6.2 years (range, 2.0-11.8 years), 73 of 152 patients in the IR cohort were alive and well without Ig dependency. IL-2 receptor gamma chain/Janus kinase 3/IL-7 receptor-deficient SCID, myeloablative conditioning, matched donor HSCT, and naive CD4 T lymphocytes >0.5×10e3/μL at+1 year were identified as independent predictors of favorable clinical and immunologic outcome.Recent advances in HSCT in SCID patients have resulted in improved OS and EFS in all genotypes and donor types. To achieve a favorable long-term outcome, treatment strategies should aim for optimal naive CD4 T lymphocyte regeneration.
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| 50. |
- Larsson, Carl, et al.
(författare)
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Modal Analysis and Finite Element Model Updating of a Timber-concrete Hyblrid Building
- 2022
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Ingår i: Proceedings of SHATIS 2022. - : Institute of Theoretical and Applied Mechanics. - 9788086246543 ; , s. 193-199
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Konferensbidrag (refereegranskat)abstract
- In recent years, there has been a rapid development of new timber products, such as cross-laminated timber, leading to an increase in buildings using timber as a structural material. House Charlie, a 4-story office building in Växjö, Sweden, is a typical example of a hybrid building that uses glulam timber for the post-beam system combined with slabs in cross-laminated timber and shear walls in concrete. A structural health monitoring system has been installed, collecting data ever since its completion in 2018. This work presents the building's modal performance collected by geophones under ambient vibrations over three years, which are used to calibrate a finite element model. The effects of changes in different material properties and model assumptions on the overall dynamic behavior of the building are shown. The aim is to establish a structural model that captures the actual behavior of the built structure that uses both timber and concrete as structural materials.
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