| 461. |
- Gosens, Jorrit, 1980, et al.
(författare)
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The role of transnational dimensions in emerging economy 'Technological Innovation Systems' for clean-tech
- 2015
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Ingår i: Journal of Cleaner Production. - : Elsevier BV. - 0959-6526 .- 1879-1786. ; 86, s. 378-388
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Tidskriftsartikel (refereegranskat)abstract
- The 'Technological Innovation System' (TIS) framework and its system functions have become a popular analytical tool for the study of clean-tech innovation. There is increasing attention for the role of emerging economies in global clean-tech innovation, but the applicability of TIS to emerging economies cases is not entirely straightforward. A key issue is the limited geographical considerations, in particular transnational dimensions in TIS, whereas earlier perspectives on innovation in emerging economies have stressed the role of such transnational dimensions. This paper elaborates transnational TIS actor-networks and institutions, categorizes these in relation to TIS functions, and describes their potential to induce or block TIS development in emerging economies. We draw on insights from the perspectives of National Learning Systems, International Technology Transfer, and Global Production Networks for this purpose. We conclude that the potential effects of these transnational dimensions may be accurately grasped by the existing list of system functions, lending credence to its further application of the TIS framework on emerging economy case studies. Policy makers in emerging economies should recognize these transnational dimensions and seek to optimize their potential effect on domestic TIS development, taking in to consideration a realistic assessment of its role in the global TIS. (C) 2014 Elsevier Ltd. All rights reserved.
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| 462. |
- Gottsäter, Erik, et al.
(författare)
-
Comparison of Models for the Design of Portal Frame Bridges with Regard to Restraint Forces
- 2017
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Ingår i: Structures Congress 2017, Denver, United States, 6-8 April 2017. - Reston, VA : American Society of Civil Engineers. - 9780784480403 ; , s. 326-339
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Konferensbidrag (refereegranskat)abstract
- In the design of concrete bridges an important aspect is limiting crack widths, since large cracks can lead to e.g. corrosion and affect the bridge functionality. Restraint forces caused by thermal loads and shrinkage will likely constitute a large part of the total forces acting on the bridge in crack width design. In this paper, restraint stresses in portal frame bridges are calculated according to Eurocode with simple hand calculation models, 2D frame models and linear elastic 3D FE-models. The results are then compared and used in Eurocode crack width design methods. Large tensile restraint stresses were found in the transverse direction close to the frame corners, and the required reinforcement amount significantly exceeded the minimum reinforcement prescribed by codes. The results are however unrealistic since the thermal load distribution is simplified, and the crack width formula does not take the reduction of restraint stresses due to cracking into account. Future studies shall therefore determine a more realistic thermal load distribution and the effects of cracking, in order to create a more accurate linear elastic 3D FE design method.
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| 463. |
- Gottsäter, Erik, et al.
(författare)
-
Crack widths in base restrained walls subjected to restraint loading
- 2019
-
Ingår i: Engineering Structures. - : Elsevier BV. - 1873-7323 .- 0141-0296. ; 189, s. 272-285
-
Tidskriftsartikel (refereegranskat)abstract
- Cracks in concrete structures can have a negative impact on durability and aesthetic appearance. It is therefore important to estimate crack widths before construction, and to use suitable reinforcement amounts to limit crack widths. Crack widths are however hard to predict in restrained structures, as cracking reduces the stiffness, which in turn reduces the restraint and thereby the amount of cracking. In this paper, nonlinear finite element analyses of cracking are performed on base restrained walls mainly subjected to shrinkage. A non-linear material model for concrete and a bond-slip relation for concrete – reinforcement interaction are used. The model does not include the hardening process of concrete but instead applies the load effects on mature concrete, and is validated by comparisons with test results from full scale tests performed in previous research. Additionally, a sensitivity study is made to investigate the influence of certain parameters on crack widths and crack patterns. The intention is to use the model in the development of a model to be used in design of concrete structures which takes restraint effects into account in an improved, yet a simplified way. The results show that the model gives realistic crack patterns, but that it tends to overestimate crack widths and the number of cracks obtained. Therefore, the model is considered to be acceptable.
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| 464. |
- Gottsäter, Erik, et al.
(författare)
-
Crack widths in portal frame bridges subjected to restraint effects
- 2019
-
Ingår i: 20th Congress of IABSE, New York City 2019: The Evolving Metropolis - Report. ; , s. 1101-1105, s. 1101-1105
-
Konferensbidrag (refereegranskat)abstract
- Restraint stresses appear in structural parts which are prevented from adjusting their shape when subjected to e.g. shrinkage or thermal actions. If the restrained stresses are large, cracking might occur, which can affect the durability of the structure. In the case of restraint effects, the reinforcement required in a bridge to limit the crack widths can be difficult to determine, as the magnitude of the restraint stresses depend on the stiffness of the structure. If cracking occurs, the stiffness is reduced and thereby also the stresses. For this reason, in structural parts affected by restraint effects, it can be hard to estimate both the number of cracks that will appear and the resulting restraint stress that governs the crack widths. In this study, crack widths in a portal frame bridge subjected to thermal actions and shrinkage were investigated using non-linear FE analysis. A bond-slip relation was used for concrete-reinforcement interaction, as the resulting crack spacing was unknown. Corresponding analysis was performed using linear elastic material models and hand calculations of crack widths, for two different thermal load cases, and relations between the results from the different methods are presented. The result can lead to the development of a more accurate design model, which would lead to more efficient use of reinforcement.
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| 465. |
- Gottsäter, Erik, et al.
(författare)
-
Measurements and simulation of temperature in a portal frame bridge
- 2018
-
Ingår i: IABSE Symposium, Nantes 2018: Tomorrow's Megastructures. - 9783857481611 ; , s. S24-9-S24-16
-
Konferensbidrag (refereegranskat)abstract
- Since thermal loads can cause cracking, they are important to consider in bridge design. In order to evaluate and develop thermal load cases based on real simulations, models for simulating temperatures can be used. In this paper, a model for thermal simulation is used to simulate temperature in a portal frame bridge outside Lund, Sweden. The results are compared with temperature measurements in 13 locations in the same bridge, which were made during a 12-month period. The results show that although many important material parameters were unknown, the model could recreate both daily and seasonal temperature variations, although it tended to render temperatures about 1°C lower than the measurements, at least during summer. The model can be used in future work in determining thermal load values for the specific bridge type, assuming the model uncertainty is considered by e.g. adding 1°C to calculated load values.
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| 466. |
- Gottsäter, Erik, et al.
(författare)
-
Simulation of thermal load distribution in portal frame bridges
- 2016
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Ingår i: IABSE Congress Stockholm, 2016: Challenges in Design and Construction of an Innovative and Sustainable Built Environment.
-
Konferensbidrag (refereegranskat)abstract
- Uneven exposure to e.g. solar radiation can cause temperature differences between various structural parts of a bridge, which leads to tensile stresses if the parts cannot move freely. In this study, thermal simulations and stress calculations on a model of a portal frame bridge are performed with the aim of evaluating the temperature difference between the bridge parts. It is shown that the temperature difference between parts which is proposed by Eurocode 1 is overestimated, thus the resulting stress distribution being unrealistic. Using the design method proposed by Eurocode 1 is therefore likely to exaggerate the required reinforcement in crack width limit design, which in turn would lead to unnecessary costs and environmental impacts. Further studies are needed in order to determine proper thermal load values and temperature distributions.
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| 467. |
- Gottsäter, Erik, et al.
(författare)
-
Simulation of thermal load distribution in portal frame bridges
- 2017
-
Ingår i: Engineering Structures. - : Elsevier BV. - 1873-7323 .- 0141-0296. ; 143, s. 219-231
-
Tidskriftsartikel (refereegranskat)abstract
- Uneven exposure to e.g. solar radiation can cause temperature differences between various structural parts of a bridge, which leads to tensile stresses if the parts cannot move freely. In this study, thermal simulations and stress calculations on a model of a portal frame bridge are performed with the aim of evaluating the temperature difference between the bridge parts. Factorial design is used in a parametric study to determine the influence of different factors on the temperature difference and the largest reasonable temperature difference obtainable for the chosen weather data. The study shows that the quasi-permanent temperature difference between parts which is proposed by Eurocode 1 is overestimated, causing tensile stresses in the transverse direction to be exaggerated significantly. Using the design method proposed by Eurocode 1 is therefore likely to overestimate the required reinforcement in crack width limit design, which in turn would lead to unnecessary costs and environmental impacts. The results also indicate that the temperature distribution within the bridge is different from what is given in Eurocode load cases, and consequently, the largest tensile stresses appear in other areas of the bridge. A simplified temperature distribution is therefore investigated and shown to give similar results as the detailed thermal simulations.
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| 468. |
- Gottsäter, Erik, et al.
(författare)
-
Validation of Temperature Simulations in a Portal Frame Bridge
- 2018
-
Ingår i: Structures. - : Elsevier BV. - 2352-0124. ; 15, s. 341-348
-
Tidskriftsartikel (refereegranskat)abstract
- In the design of bridges, thermal loads are important to take into account since they can cause cracking if the structure or structural part is restrained from changing its size. Accurate thermal load values must therefore be used in bridge design, based on knowledge of the actual temperature distribution in the bridge. This paper presents the validation of a model for temperature simulation, to be used in future work in the determination of temperature differences between deck and abutments in portal frame bridges. The validation is performed by comparing simulated temperatures with temperatures measured at 13 locations in a portal frame bridge during a period of 12 months. The simulation model uses measured air temperature, wind speed and long- and short wave radiation as input to calculate the temperature for every hour in the time period, and includes the soil beside the bridge. The results show that the model was capable of predicting the temperature distribution adequately, and that conservative values of the temperature difference between the structural parts can be obtained by adding no more than a ΔT of 1.5 °C to the simulated temperature difference, depending on the application.
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| 469. |
- Gou, Shaoqing, et al.
(författare)
-
Passive design optimization of newly-built residential buildings in Shanghai for improving indoor thermal comfort while reducing building energy demand
- 2018
-
Ingår i: Energy and Buildings. - : Elsevier BV. - 0378-7788. ; 169, s. 484-506
-
Tidskriftsartikel (refereegranskat)abstract
- The objective of this paper is to optimize the passive design of newly-built residential buildings in hot summer and cold winter region of China for improving indoor thermal comfort while reducing building energy demand. In this respect, this paper investigates the performance of a representative apartment building in the city of Shanghai and evaluates the optimum solutions by using a developed optimization approach, which includes three major steps of 1) setting the model for multi-objective optimization, 2) sensitivity analysis for reducing the dimension of input variables, and 3) multi-objective optimization by using the Non-dominated Sorting Genetic Algorithm II (NSGA-II) coupled with the Artificial Neural Network (ANN), among which a novel indicator for evaluating the annual indoor thermal comfort of residential buildings of Shanghai named Comfort Time Ratio (CTR) is defined based on the modification of Szokolay's theory in terms of bioclimatic analysis, and the impacts of passive design variables on the indoor thermal comfort and building energy demand in terms of different directions are comprehensively investigated. Results of the multi-objective optimization indicate that the residential buildings of Shanghai have a great potential in comfort-improvement and energy-saving. A series of novel optimal passive design tactics for residential buildings in Shanghai are derived accordingly which could be easily understood and conveniently carried out by the architects in practice.
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| 470. |
- Goyal, Gaurav, 1983, et al.
(författare)
-
A simple cut and stretch assay to detect antimicrobial resistance genes on bacterial plasmids by single-molecule fluorescence microscopy
- 2022
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 12:1
-
Tidskriftsartikel (refereegranskat)abstract
- Antimicrobial resistance (AMR) is a fast-growing threat to global health. The genes conferring AMR to bacteria are often located on plasmids, circular extrachromosomal DNA molecules that can be transferred between bacterial strains and species. Therefore, effective methods to characterize bacterial plasmids and detect the presence of resistance genes can assist in managing AMR, for example, during outbreaks in hospitals. However, existing methods for plasmid analysis either provide limited information or are expensive and challenging to implement in low-resource settings. Herein, we present a simple assay based on CRISPR/Cas9 excision and DNA combing to detect antimicrobial resistance genes on bacterial plasmids. Cas9 recognizes the gene of interest and makes a double-stranded DNA cut, causing the circular plasmid to linearize. The change in plasmid configuration from circular to linear, and hence the presence of the AMR gene, is detected by stretching the plasmids on a glass surface and visualizing by fluorescence microscopy. This single-molecule imaging based assay is inexpensive, fast, and in addition to detecting the presence of AMR genes, it provides detailed information on the number and size of plasmids in the sample. We demonstrate the detection of several beta-lactamase-encoding genes on plasmids isolated from clinical samples. Furthermore, we demonstrate that the assay can be performed using standard microbiology and clinical laboratory equipment, making it suitable for low-resource settings.
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