| 28361. |
- Karlsson, Ida, 1980, et al.
(author)
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Roadmap for Decarbonization of the Building and Construction Industry - A Supply Chain Analysis Including Primary Production of Steel and Cement
- 2020
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In: Energies. - : MDPI AG. - 1996-1073 .- 1996-1073. ; 13:16
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Journal article (peer-reviewed)abstract
- Sweden has committed to reducing greenhouse gas (GHG) emissions to net-zero by 2045. Around 20% of Sweden's annual CO(2)emissions arise from manufacturing, transporting, and processing of construction materials for construction and refurbishment of buildings and infrastructure. In this study, material and energy flows for building and transport infrastructure construction is outlined, together with a roadmap detailing how the flows change depending on different technical and strategical choices. By matching short-term and long-term goals with specific technology solutions, these pathways make it possible to identify key decision points and potential synergies, competing goals, and lock-in effects. The results show that it is possible to reduce CO(2)emissions associated with construction of buildings and transport infrastructure by 50% to 2030 applying already available measures, and reach close to zero emissions by 2045, while indicating that strategic choices with respect to process technologies and energy carriers may have different implications on energy use and CO(2)emissions over time. The results also illustrate the importance of intensifying efforts to identify and manage both soft and hard barriers and the importance of simultaneously acting now by implementing available measures (e.g., material efficiency and material/fuel substitution measures), while actively planning for long-term measures (low-CO(2)steel or cement).
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| 28362. |
- Karlsson, Johannes, 1990, et al.
(author)
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Agent-Based Investigation of Charger Queues and Utilization of Public Chargers for Electric Long-Haul Trucks
- 2023
-
In: Energies. - 1996-1073 .- 1996-1073. ; 16:12
-
Journal article (peer-reviewed)abstract
- This paper investigates the charging needs and charger utilisation of a system of battery electric trucks and their public fast chargers, along the highway between the Swedish cities of Helsingborg and Stockholm, in a possible future scenario in which all trucks are battery electric. The system is investigated via an agent-based model which simulates a typical day with current levels of truck traffic on the road. The traffic flow is based on hourly truck flow data during a day and the annual flow of trucks. The findings indicate major potential for a well-functioning system of public chargers for trucks, with high utilisation, few queuing problems at charging stations, cheap public fast charging and a robust response to queues caused by peaks or increases in the traffic flow. The number of 900 kW chargers along the road needed to achieve this has been estimated at 140, and the utilisation factor for the chargers is predicted to be 30%.
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| 28363. |
- Karlsson, J., et al.
(author)
-
An Error Estimate for Symplectic Euler Approximation of Optimal Control Problems
- 2015
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In: SIAM Journal on Scientific Computing. - : Society for Industrial & Applied Mathematics (SIAM). - 1064-8275 .- 1095-7197. ; 37:2, s. A946-A969
-
Journal article (peer-reviewed)abstract
- This work focuses on numerical solutions of optimal control problems. A time discretization error representation is derived for the approximation of the associated value function. It concerns symplectic Euler solutions of the Hamiltonian system connected with the optimal control problem. The error representation has a leading-order term consisting of an error density that is computable from symplectic Euler solutions. Under an assumption of the pathwise convergence of the approximate dual function as the maximum time step goes to zero, we prove that the remainder is of higher order than the leading-error density part in the error representation. With the error representation, it is possible to perform adaptive time stepping. We apply an adaptive algorithm originally developed for ordinary differential equations. The performance is illustrated by numerical tests.
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| 28364. |
- Karlsson, Johan, 1984, et al.
(author)
-
Atomically resolved tissue integration
- 2014
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In: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 14:8, s. 4220-4223
-
Journal article (peer-reviewed)abstract
- In the field of biomedical technology, a critical aspect is the ability to control and understand the integration of an implantable device in living tissue. Despite the technical advances in the development of biomaterials, the elaborate interplay encompassing materials science and biology on the atomic level is not very well understood. Within implantology, anchoring a biomaterial device into bone tissue is termed osseointegration. In the most accepted theory, osseointegration is defined as an interfacial bonding between implant and bone; however, there is lack of experimental evidence to confirm this. Here we show that atom probe tomography can be used to study the implant-tissue interaction, allowing for three-dimensional atomic mapping of the interface region. Interestingly, our analyses demonstrated that direct contact between Ca atoms and the implanted titanium oxide surface is formed without the presence of a protein interlayer, which means that a pure inorganic interface is created, hence giving experimental support to the current theory of osseointegration. We foresee that this result will be of importance in the development of future biomaterials as well as in the design of in vitro evaluation techniques.
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| 28365. |
- Karlsson, Johannes, 1990, et al.
(author)
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Case Study of Cost-Effective Electrification of Long-Distance Line-Haul Trucks
- 2023
-
In: Energies. - : MDPI AG. - 1996-1073 .- 1996-1073. ; 16:6
-
Journal article (peer-reviewed)abstract
- This paper investigates the economic consequences of a haulage company replacing its line-haul diesel trucks with battery-electric ones. It also examines how large truck batteries should be, whether the haulage companies should use public fast chargers to complement their own, and whether public fast chargers have the potential to be profitable. The potential extra cost of losing payload capacity is estimated and there is an investigation of whether a charge-point operator should meet the peak demand for charging. The case under analysis is designed to represent a typical line-haul service between terminals in a major logistics system, with the finding that, in this case, a transition to battery-electric trucks seems cost effective for the company. Moreover, it is advisable for the company to use public fast chargers and these will likely become profitable given that the utilisation factor of the investigated public fast chargers may realistically exceed 20%.
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| 28366. |
- Karlsson, Johan, 1991, et al.
(author)
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Comparison between mixed-integer and second order cone programming for autonomous overtaking
- 2018
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In: 2018 European Control Conference (ECC).
-
Conference paper (peer-reviewed)abstract
- This paper concerns optimally controlling an autonomous vehicle to perform safe and comfortable overtaking of a slower moving leading vehicle. The contribution is an analysis of the comparisons between a convex relaxation with the standard mixed integer quadratic program. The main difference between the formulations is that the sampling is performed in the temporal domain in the standard formulation, but in the spatial domain for the convex relaxation. The case of varying lateral position and longitudinal velocity is studied for both algorithms and the solution quality and computational effort are discussed. The results are given in a case study where an ego vehicle is forced to accelerate when overtaking a leading vehicle, due to the presence of an oncoming vehicle. The results illustrate that the temporal and spatial formulation’s yield similar solutions but obtaining
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| 28367. |
- Karlsson, Johan, 1991, et al.
(author)
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Computationally efficient autonomous overtaking on highways
- 2020
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In: IEEE Transactions on Intelligent Transportation Systems. - 1524-9050 .- 1558-0016. ; 21:8, s. 3169-3183
-
Journal article (peer-reviewed)abstract
- This paper studies the problem of optimal overtaking of a slow-moving leading vehicle in the presence of oncoming and/or adjacent vehicles with varying but known longitudinal speeds. A computationally efficient modeling approach is introduced, in which the overtaking problem is formulated by sampling in relative distance to the leading vehicle, replacing velocity state with its inverse and utilizing a nonlinear change of control variables. These three steps achieve a computationally efficient nonlinear control problem that can be solved using the sequential quadratic programming. Measures have been taken to ensure the feasibility of the nonlinear problem, even when the sequential quadratic programming iterates are stopped prematurely. A case study is presented, where this new formulation is compared with the previously published formulations in terms of solution quality and computation time.
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| 28368. |
- Karlsson, Johan, 1984, et al.
(author)
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Controlling drug delivery kinetics from mesoporous titania thin films by pore size and surface energy
- 2015
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In: International journal of nanomedicine. - 1176-9114 .- 1178-2013. ; 10, s. 4425-4436
-
Journal article (peer-reviewed)abstract
- The osseointegration capacity of bone-anchoring implants can be improved by the use of drugs that are administrated by an inbuilt drug delivery system. However, to attain superior control of drug delivery and to have the ability to administer drugs of varying size, including proteins, further material development of drug carriers is needed. Mesoporous materials have shown great potential in drug delivery applications to provide and maintain a drug concentration within the therapeutic window for the desired period of time. Moreover, drug delivery from coatings consisting of mesoporous titania has shown to be promising to improve healing of bone-anchoring implants. Here we report on how the delivery of an osteoporosis drug, alendronate, can be controlled by altering pore size and surface energy of mesoporous titania thin films. The pore size was varied from 3.4 nm to 7.2 nm by the use of different structure-directing templates and addition of a swelling agent. The surface energy was also altered by grafting dimethylsilane to the pore walls. The drug uptake and release profiles were monitored in situ using quartz crystal microbalance with dissipation (QCM-D) and it was shown that both pore size and surface energy had a profound effect on both the adsorption and release kinetics of alendronate. The QCM-D data provided evidence that the drug delivery from mesoporous titania films is controlled by a binding-diffusion mechanism. The yielded knowledge of release kinetics is crucial in order to improve the in vivo tissue response associated to therapeutic treatments.
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| 28369. |
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| 28370. |
- Karlsson, Jakob, 1997, et al.
(author)
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Effect of heating of pea fibres on their swelling, rheological properties and in vitro colon fermentation
- 2024
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In: Food Hydrocolloids. - : Elsevier. - 0268-005X .- 1873-7137. ; 147
-
Journal article (peer-reviewed)abstract
- Dietary fibre intake is essential for all human beings and has been correlated to beneficial health effects. Pea hull fibres (PF) are generally seen as a side stream during extraction of protein and starch from yellow pea but could be used in various food products to boost fibre content. In this study, the thermal treatment of pea hull fibres was investigated in terms of physicochemical properties and in vitro colonic fermentation. The PF that was subjected to heating showed an increase of fibres solubilised in the liquid and particle size. Results also showed that viscosity and storage modulus increased with thermal treatment, possibly due to the swelling of the PF. The pea fibre was readily fermentable based on total gas production and pH. However, the susceptibility to fermentation of PF did not increase with thermal treatment. Total gas production and short chain fatty acid produced were similar independent of thermal treatment. Conclusively, heating of the PF resulted in increased ability to structure water suspension, owing to increased fibre particle size, but is not sufficient to increase short chain fatty acid production during colonic fermentation. To explain this, we propose that the changes in cell wall structure were not major enough to induce higher fermentability.
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