| 1. |
- Agredo Chavez, Angelica Maria, et al.
(författare)
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Cracking and Fatigue of Heavy Loaded Prestressed Concrete Bridge in Sweden
- 2022
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Ingår i: IABSE Symposium Prague 2022: Challenges for Existing and Oncoming Structures - Report, International Association for Bridge and Structural Engineering. - Zürich : International Association for Bridge and Structural Engineering. ; , s. 792-799
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Konferensbidrag (refereegranskat)abstract
- A prestressed concrete bridge was built in 1963 with BBRV cables. It has three spans and a total length of 134.8 m. Due to mining activities the bridge was loaded with trucks with a total weight of 90 ton during 2012-2014 and from 2019. Crack development has been monitored manually and from 2020 with strain gauges and LVDTs.Cracks normally vary between 0.1 to 0.3 mm in width and grow in length with time. In November 2020 some of the strain gauges on the concrete showed alarming growth and the bridge was closed for traffic. Additional strain gauges were installed on vertical reinforcement bars and an assessment was carried out of the fatigue capacity of the bridge. It was found that the new strain gauges did not indicate any growth in strain and that the fatigue capacity was sufficient. The bridge could be opened again for traffic after being closed for five weeks. Monitoring drift in the strain gauges and fatigue are discussed.
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| 2. |
- Andersson, Emil, 1982-
(författare)
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Reinterpreting Liberal Legitimacy
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis is an inquiry into the Liberal Principle of Legitimacy, formulated by John Rawls in his later writings. According to this principle, the exercise of political power is legitimate only if it is justifiable to all citizens. This view can be interpreted in different ways, and I argue that the presently most popular way of doing so faces serious problems. The aim is to identify and defend a more plausible version of the principle, which overcomes these problems, and yet preserves the most essential and appealing features of the approach. Among the most central issues for how to interpret the principle are how to understand the notion of justifiability to a person, and who should be included in the group of persons referred to as "all citizens". On the currently received view, only justifiability to those who count as "reasonable" matter, and justifiability to these persons is understood in non-moral terms, as being determined by what is accessible to them, given the beliefs that they happen to hold. I argue that we have good reasons to reject both of these suggestions. We should instead spell out justifiability to a person in terms of what could be reasonably accepted in a moral sense, which allows us to retain the appealing idea that legitimacy is dependent on justifiability to all citizens over whom political power is exercised. I further suggest that we can use the original position – Rawls’s version of the social contract – to determine what is justifiable to all in this sense. I defend this suggestion against the expected objection that it will not be able to take reasonable pluralism – the assumption of deep disagreement between citizens – into account, by explaining why we should sharply distinguish this principle of political legitimacy from the theory of Political Liberalism. This distinction also contributes to my response to the objection, raised against this principle, that it is self-defeating. That my suggested interpretation allows us to convincingly respond to this line of criticism is yet another reason as to why it is preferable to the standard view.
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| 3. |
- Andersson, Kasper G, et al.
(författare)
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Revision of deposition and weathering parameters for the ingestion dose module (ECOSYS) of the ARGOS and RODOS decision support systems.
- 2011
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Ingår i: Journal of environmental radioactivity. - : Elsevier BV. - 1879-1700 .- 0265-931X.
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Tidskriftsartikel (refereegranskat)abstract
- The ECOSYS model is the ingestion dose model integrated in the ARGOS and RODOS decision support systems for nuclear emergency management. The parameters used in this model have however not been updated in recent years, where the level of knowledge on various environmental processes has increased considerably. A Nordic work group has carried out a series of evaluations of the general validity of current ECOSYS default parameters. This paper specifically discusses the parameter revisions required with respect to the modelling of deposition and natural weathering of contaminants on agricultural crops, to enable the trustworthy prognostic modelling that is essential to ensure justification and optimisation of countermeasure strategies. New modelling approaches are outlined, since it was found that current ECOSYS approaches for deposition and natural weathering could lead to large prognostic errors.
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| 4. |
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| 5. |
- Bradley, Siobhan J., et al.
(författare)
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Heterogeneity in the fluorescence of graphene and graphene oxide quantum dots
- 2017
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Ingår i: Microchimica Acta. - : Springer Science and Business Media LLC. - 0026-3672 .- 1436-5073. ; 184:3, s. 871-878
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Tidskriftsartikel (refereegranskat)abstract
- Heterogeneity is an inherent property of a wealth of real-world nanomaterials and yet rarely in the reporting of new properties is its effect sufficiently addressed. Graphene quantum dots (GQDs) – fluorescent, nanoscale fragments of graphene - are an extreme example of a heterogeneous nanomaterial. Here, top-down approaches – by far the most predominant – produce batches of particles with a distribution of sizes, shapes, extent of oxidation, chemical impurities and more. This makes characterization of these materials using bulk techniques particularly complex and comparisons of properties across different synthetic methods uninformative. In particular, it hinders the understanding of the structural origin of their fluorescence properties. We present a simple synthetic method, which produces graphene quantum dots with very low oxygen content that can be suspended in organic solvents, suggesting a very pristine material. We use this material to illustrate the limitations of interpreting complex data sets generated by heterogeneous materials and we highlight how misleading this “pristine” interpretation is by comparison with graphene oxide quantum dots synthesized using an established protocol. In addition, we report on the solvatochromic properties of these particles, discuss common characterization techniques and their limitations in attributing properties to heterogeneous materials.
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| 6. |
- Bågmark, Kasper, 1995, et al.
(författare)
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An energy-based deep splitting method for the nonlinear filtering problem
- 2023
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Ingår i: Partial Differential Equations and Applications. - : Springer Science and Business Media LLC. - 2662-2963 .- 2662-2971. ; 4:2
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this paper is to explore the use of deep learning for the solution of the nonlinear filtering problem. This is achieved by solving the Zakai equation by a deep splitting method, previously developed for approximate solution of (stochastic) partial differential equations. This is combined with an energy-based model for the approximation of functions by a deep neural network. This results in a computationally fast filter that takes observations as input and that does not require re-training when new observations are received. The method is tested on four examples, two linear in one and twenty dimensions and two nonlinear in one dimension. The method shows promising performance when benchmarked against the Kalman filter and the bootstrap particle filter.
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| 7. |
- Bäckman, Johan, et al.
(författare)
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Activity and migratory flights of individual free-flying songbirds throughout the annual cycle : Method and first case study
- 2017
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Ingår i: Journal of Avian Biology. - : Wiley. - 0908-8857. ; 48:2, s. 309-319
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Tidskriftsartikel (refereegranskat)abstract
- We describe a method and device (< 1.2 g) for recording, processing and storing data about activity and location of individuals of free-living songbirds throughout the annual cycle. Activity level was determined every five minutes from five 100 ms samples of accelerometer data with 5 s between the sampling events. Activity levels were stored on an hourly basis throughout the annual cycle, allowing periods of resting/sleep, continuous flight and intermediate activity (foraging, breeding) to be distinguished. Measurements from a light sensor were stored from preprogrammed key stationary periods during the year to provide control information about geographic location. Successful results, including annual actogram, were obtained for a red-backed shrike Lanius collurio carrying out its annual loop migration between northern Europe and southern Africa. The shrike completed its annual migration by performing > 66 (max. 73) nocturnal migratory flights (29 flights in autumn and > 37, max. 44, in spring) adding up to a total of > 434 (max. 495) flight hours. Migratory flights lasted on average 6.6 h with maximum 15.9 h. These flights were aggregated into eight travel episodes (periods of 4-11 nights when flights took place on the majority of nights). Daytime resting levels were much higher during the winter period compared to breeding and final part of spring migration. Daytime resting showed peaks during days between successive nocturnal flights across Sahara, continental Africa and the Arabian Peninsula, indicating that the bird was mostly sleeping between these long migratory flights. Annual activity and flight data for free-living songbirds will open up many new research possibilities. Main topics that can be addressed are e.g. migratory flight performance (total flight investment, numbers and characteristics of flights), timing of stationary periods, activity patterns (resting/sleep, activity level) in different phases of the annual cycle and variability in the annual activity patterns between and within individuals.
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| 8. |
- Darmadi, Iwan, 1990, et al.
(författare)
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Bulk-Processed Pd Nanocube-Poly(methyl methacrylate) Nanocomposites as Plasmonic Plastics for Hydrogen Sensing
- 2020
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Ingår i: ACS Applied Nano Materials. - : American Chemical Society (ACS). - 2574-0970. ; 3:8, s. 8438-8445
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Tidskriftsartikel (refereegranskat)abstract
- Nanoplasmonic hydrogen sensors are predicted to play a key role in safety systems of the emerging hydrogen economy. Pd nanoparticles are the active material of choice for sensor prototype development due to their ability to form a hydride at ambient conditions, which creates the optical contrast. Here, we introduce plasmonic hydrogen sensors made from a thermoplastic nanocomposite material, that is, a bulk material that can be molded with standard plastic processing techniques, such as extrusion and three-dimensional (3D) printing, while at the same time being functionalized at the nanoscale. Specifically, our plasmonic plastic is composed of hydrogensensitive and plasmonically active Pd nanocubes mixed with a poly(methyl methacrylate) matrix, and we optimize it by characterization from the atomic to the macroscopic level. We demonstrate meltprocessed deactivation-resistant plasmonic hydrogen sensors, which retain full functionality even after SO weeks. From a wider perspective, we advertise plasmonic plastic nanocomposite materials for application in a multitude of active plasmonic technologies since they provide efficient scalable processing and almost endless functional material design opportunities via tailored polymer- colloidal nanocrystal combinations.
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| 9. |
- Darmadi, Iwan, 1990, et al.
(författare)
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Plasma Cleaning of Cationic Surfactants from Pd Nanoparticle Surfaces: Implications for Hydrogen Sorption
- 2023
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Ingår i: ACS Applied Nano Materials. - 2574-0970. ; 6:10, s. 8168-8177
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Tidskriftsartikel (refereegranskat)abstract
- Cationic surfactants are widely used in the colloidal synthesis of noble metal nanoparticles in general, and of Pd nanoparticles in particular, to stabilize them toward aggregate formation in solution and to promote shape-specific particle growth. Despite the benefits at the synthesis stage, these surfactants can be problematic once the nanoparticles are to be applied as they may both geometrically block and electronically alter surface sites that are important for surface chemical reactions. This is particularly relevant in applications like bio- and chemosensors where analyte-nanoparticle surface interactions constitute the actual sensing event. Here, H2 sensors based on Pd and its alloys are no exception since the dissociation of H2 on the particle surface is the first step toward hydride formation and thus hydrogen detection, and it has been demonstrated that the presence of surfactant molecules detrimentally affects the hydrogen sorption rate. Here, we therefore develop a scheme to remove cationic surfactants from Pd nanoparticle surfaces by means of subsequent O2 and H2 plasma treatment, whose effectiveness we verify by X-ray photoelectron spectroscopy. Furthermore, we find that the plasma treatment both alters the surface structure of the Pd nanoparticles at the atomic level and leads to surface contamination by so-called H2 plasma swift chemical sputtering of Al, Si and F species present in the plasma chamber, which in combination significantly reduce hydrogen sorption rates and increase apparent activation energies, as revealed by plasmonic hydrogen sorption kinetic measurements. Finally, we show that both these effects can be reversed by mild thermal annealing and that after the complete plasma cleaning-thermal annealing sequence hydrogen sorption rates essentially identical to the ones of neat Pd particles never exposed to cationic surfactants can be achieved. This advertises tailored plasma cleaning and mild heat treatments as an effective recipe for the removal of surfactant molecules from nanoparticle surfaces.
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| 10. |
- Ene, Daniela, et al.
(författare)
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Management of Tritium in European Spallation Source
- 2015
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Ingår i: Fusion Science and Technology. - 1536-1055. ; 67:2, s. 324-327
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Tidskriftsartikel (refereegranskat)abstract
- The European Spallation Source (ESS) will produce tritium via spallation and activation processes during operational activities. Within the location of ESS facility in Lund, Sweden site it is mandatory to demonstrate that the management strategy of the produced tritium ensures the compliance with the country regulation criteria. The aim of this paper is to give an overview of the different aspects of the tritium management in ESS facility. Besides the design parameter study of the helium coolant purification system of the target the consequences of the tritium releasing into the environment were also analyzed. Calculations shown that the annual release of tritium during the normal operations represents a small fraction from the estimated total dose. However, more refined calculations of migration of activated-groundwater should be performed for higher hydraulic conductivities, with the availability of the results on soil examinations. With the assumption of 100% release of tritium to the atmosphere during the occurring of the extreme accidents, it was found as well that the total dose complies with the constraint.
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