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| 2. |
- Björnfot, Cecilia, et al.
(författare)
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Assessing cerebral arterial pulse wave velocity using 4D flow MRI
- 2021
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Ingår i: Journal of Cerebral Blood Flow and Metabolism. - : Sage Publications. - 0271-678X .- 1559-7016. ; 41:10, s. 2769-2777
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Tidskriftsartikel (refereegranskat)abstract
- Intracranial arterial stiffening is a potential early marker of emerging cerebrovascular dysfunction and could be mechanistically involved in disease processes detrimental to brain function via several pathways. A prominent consequence of arterial wall stiffening is the increased velocity at which the systolic pressure pulse wave propagates through the vasculature. Previous non-invasive measurements of the pulse wave propagation have been performed on the aorta or extracranial arteries with results linking increased pulse wave velocity to brain pathology. However, there is a lack of intracranial “target-organ” measurements. Here we present a 4D flow MRI method to estimate pulse wave velocity in the intracranial vascular tree. The method utilizes the full detectable branching structure of the cerebral vascular tree in an optimization framework that exploits small temporal shifts that exists between waveforms sampled at varying depths in the vasculature. The method is shown to be stable in an internal consistency test, and of sufficient sensitivity to robustly detect age-related increases in intracranial pulse wave velocity.
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| 3. |
- Björnfot, Cecilia, et al.
(författare)
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Cerebral arterial stiffness is linked to white matter hyperintensities and perivascular spaces in older adults : a 4D flow MRI study
- 2024
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Ingår i: Journal of Cerebral Blood Flow and Metabolism. - : Sage Publications. - 0271-678X .- 1559-7016.
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Tidskriftsartikel (refereegranskat)abstract
- White matter hyperintensities (WMH), perivascular spaces (PVS) and lacunes are common MRI features of small vessel disease (SVD). However, no shared underlying pathological mechanism has been identified. We investigated whether SVD burden, in terms of WMH, PVS and lacune status, was related to changes in the cerebral arterial wall by applying global cerebral pulse wave velocity (gcPWV) measurements, a newly described marker of cerebral vascular stiffness. In a population-based cohort of 190 individuals, 66–85 years old, SVD features were estimated from T1-weighted and FLAIR images while gcPWV was estimated from 4D flow MRI data. Additionally, the gcPWV’s stability to variations in field-of-view was analyzed. The gcPWV was 10.82 (3.94) m/s and displayed a significant correlation to WMH and white matter PVS volume (r = 0.29, p < 0.001; r = 0.21, p = 0.004 respectively from nonparametric tests) that persisted after adjusting for age, blood pressure variables, body mass index, ApoB/A1 ratio, smoking as well as cerebral pulsatility index, a previously suggested early marker of SVD. The gcPWV displayed satisfactory stability to field-of-view variations. Our results suggest that SVD is accompanied by changes in the cerebral arterial wall that can be captured by considering the velocity of the pulse wave transmission through the cerebral arterial network.
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| 6. |
- Berg, Sven, et al.
(författare)
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In-plane Shear Modulus of Cross-laminated Timber by Diagonal Compression Test
- 2019
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Ingår i: BioResources. - : NC State University. - 1930-2126 .- 1930-2126. ; 14:3, s. 5559-5572
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Tidskriftsartikel (refereegranskat)abstract
- Cross-laminated timber (CLT) is an engineered wood material that is used in the construction industry, e.g., for floors, walls, and beams. In cases where CLT-elements are used as shear walls, the in-plane-stiffness is an important property. For non-edge glued CLT, in-plane shear stiffness is lower than for edge-glued CLT. To evaluate the non-edge glued CLT panel’s in-plane shear modulus, the diagonal compression test and finite element (FE) simulation was used. FE-models with both isotropic and orthotropic material models were used to calculate the shear stiffness. The FE models using pure shear loads were used as a reference to determine the correct value of the shear modulus. To verify the FE simulations, diagonal compression tests were conducted on 30 CLT samples. A calibration formula was derived using the least square method for calculation of shear modulus. The formula gave accurate results. The results showed that FE simulations can reproduce the same shear stiffness as tests of non-edge glued 3-layer and 5-layer CLT panels.
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| 7. |
- Bildsten, Louise, et al.
(författare)
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Value-driven Purchasing of Kitchen Cabinets in Industrialized Housing
- 2011
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Ingår i: Journal of Financial Management of Property and Construction. - : Emerald Group Publishing Limited. - 1366-4387 .- 1363-2175. ; 16:1, s. 73-83
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Tidskriftsartikel (refereegranskat)abstract
- Purpose - This article hypothesises that value-driven purchasing of customized kitchen cabinets is more profitable than market-driven purchasing in industrialized housing construction. The hypothesis is examined through a case study of kitchen carpentry at one of Sweden’s largest producers of industrialized prefabricated multi-storey housing. By comparing characteristics of market-driven vs. value-driven purchasing, this article aims to further clarify the benefits and drawbacks of these two strategies. Design/methodology/approach - A theoretical framework is proposed by comparing characteristics of market-driven vs. value-driven purchasing that clarifies the benefits and drawbacks of these two strategies. An explorative case study of kitchen carpentry at a house manufacturer illustrates purchasing of kitchen cabinets in the industrialized housing industry in relation to the proposed framework. Findings – According to the case study, from a value perspective, a long-term relationship with a dedicated local, smaller supplier is a preferable choice over a short-term bulk supplier, even if the short-term supplier has (much) lower prices. Research limitations/implications – This is a single-case study that should be verified by further empirical work of a test-delivery from the local sub-system manufacturer. Such a study would provide more insights into this area of work and make it possible to thoroughly evaluate potential risks. The indicative results in this paper can be made conclusive through quantification of the proposed Lean purchasing characteristics. Originality/value – A comparison of value-driven and market-driven purchasing is carried out in theory and applied to a real case study that brings new perspectives to purchasing. In this way, the article proposes alternative purchasing strategies to the construction industry.
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| 8. |
- Bildsten, Louise, 1975-, et al.
(författare)
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Value-driven vs Market-driven Purchasing of Kitchen Cabinets
- 2010
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Ingår i: Conference Proceeding 18th annual conference of the International Group for Lean Construction. - Haifa : Technion-Israel Institute of Technology. ; , s. 202-211
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In economic and management literature, the relationship between supplier and buyer can be more or less intimate. It can vary from market-driven with a constant change of suppliers to a value-driven relationship with one sole supplier. Purchasing strategies of construction companies have often been described as short-sighted, where price is the most considered aspect. Recent lean management literature promote value-driven purchasing, since it provides benefits such as just-in-time delivery, zero defects and customized products through close technical collaboration. This article hypothesises that value-driven purchasing of customized kitchen cabinets is more profitable than market-driven purchasing in industrialized housing construction. The hypothesis is examined through a case study of kitchen carpentry at one of Sweden’s largest producers of industrialized prefabricated multi-storey housing. By comparing characteristics of market-driven vs. value-driven purchasing, this article aims to further clarify the benefits and drawbacks of these two strategies. At the case company, kitchens are ordered cabinet-by-cabinet and then installed inside the factory. The company is considering the possibility of a long-term relationship with a smaller local supplier that can deliver a new kind of innovative kitchen cabinet solution that is prefabricated. If the local supplier can meet the expectations of just-in-time delivery, zero defects and a product “tailor-made” for the housing company, there is much to gain.
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| 9. |
- Björnfot, Anders, et al.
(författare)
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A design structural matrix approach displaying structural and assembly requirements in construction : a timber case study
- 2007
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Ingår i: Journal of engineering design (Print). - : Informa UK Limited. - 0954-4828 .- 1466-1837. ; 18:2, s. 113-124
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Tidskriftsartikel (refereegranskat)abstract
- A fundamental demand of construction design is human safety from structural failure. As a consequence, buildings generally tend to be structurally optimized with cost as the main target parameter. However, a cost-suboptimized structural design often leads to poor constructability decisions with subsequent waste. This paper presents initial research in the development of a design structural matrix (DSM) method able to identify constructability obstacles between structural design and assembly and thus eliminate waste. Empirical data based on a case study of long-span timber structures is used in the development and analysis of the method. The DSM was found to be a holistic tool for systematic consideration of structural design and constructability requirements by providing a standardized system view, a detailed element view, and physical and functional interactions among elements and modules. The DSM was also shown to aid in detailed design and production management through the use of simple matrix tools.
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