| 1. |
- Boström, Tobias, 1975-
(författare)
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Solution-Chemically Derived Spectrally Selective Solar Absorbers : With System Perspectives on Solar Heating
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis consists of two parts, one dominating part concerning spectrally selective solar absorbers and one dealing with thermal solar systems. The appended papers I to VIII concern the solar absorber part, papers dealing with the systems part have not been included in the thesis.A new spectrally selective absorber derived from a novel solution-chemistry method has been developed and optimized. The main objective was to investigate the potential of the spectrally selective surface. Some of the questions at issue were; would it be possible to create a suitable absorber composite using this method, how high selectivity could be obtained, could the performance be enhanced by using anti-reflection coatings, which was the optimal layer composition, would the thin films be durable and what was the structure and morphology like on a nano scale? The absorber consists of absorbing thin films of nickel nano-particles embedded in a dielectric matrix of alumina and an overlying anti-reflection film consisting of one of the following materials silica, hybrid-silica, alumina or silica-titania. Solution and sol-gel chemistry were used in the process. The thin films were spin-coated onto an aluminum substrate followed by a heat-treatment that generated the multi layer selective solar absorber. The optical constants for the thin film materials in question were determined. An optimal three layer structure was modeled using the experimentally determined optical constants. The theoretical three layer stack was experimentally confirmed and achieved a solar absorptance of 0.97 and a thermal emittance of 0.05 which definitely are commercially competitive values. The configuration of the three layer stack is: an 80%nickel-20%alumina film at the base, a 40%nickel-60%alumina film in the middle and a silica or hybrid-silica film at the top. The three layer absorber was subjected to high temperature and condensation accelerated ageing tests designed by IEA Task 27. The condensation test did not degrade the absorber whatsoever but the high temperature test did reveal some oxidation of the nickel particles. The oxidation occurs initially and then stops. A formed nickel-oxide layer hinders further oxidation. The level of oxidation is small and the absorber is qualified according to the IEA Task 27 test procedure.
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| 2. |
- Husberg, Tobias, 1975, et al.
(författare)
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Analysis of advanced multiple injection strategies in a heavy-duty diesel engine using optical measurements and CFD-simulations
- 2008
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Ingår i: SAE Technical Papers. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191 .- 2688-3627.
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Tidskriftsartikel (refereegranskat)abstract
- In order to meet future emissions legislation for Diesel engines and reduce their CO 2 emissions it is necessary to improve diesel combustion by reducing the emissions it generates, while maintaining high efficiency and low fuel consumption. Advanced injection strategies offer possible ways to improve the trade-offs between NOx, PM and fuel consumption. In particular, use of high EGR levels ( > 40%) together with multiple injection strategies provides possibilities to reduce both engine-out NOx and soot emissions. Comparisons of optical engine measurements with CFD simulations enable detailed analysis of such combustion concepts. Thus, CFD simulations are important aids to understanding combustion phenomena, but the models used need to be able to model cases with advanced injection strategies. Thus, in the study presented here, engine tests were performed with settings selected to simplify CFD simulation, with long dwell times between the injections and only injection changes between engine settings in test cases presented in this paper. The key to reducing both soot and NOx emissions by applying pilot injections is that the pilot injected fuel should not ignite before sufficient mixing/lean-out has occurred. Hence, substantial heat releases prior to the main injection must be prevented. Thus, high EGR levels are needed to increase the bulk gas mass and reduce the temperature so that there is sufficient time for the pilot injections to mix and become locally lean before ignition. Copyright © 2008 SAE International.
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| 3. |
- Karlsson, Tobias, 1975, et al.
(författare)
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Levnadsbanor och rörlighet i den mogna industristaden: En introduktion : Tobias Karlsson & Christer Lundh (red), Liv i rörelse: Göteborgs befolkning och arbetsmarknad 1900-1950.
- 2022
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Ingår i: Liv i rörelse: Göteborgs befolkning och arbetsmarknad 1900-1950 / Karlsson T. & Lundh C. (red.).. - Lund : Nordic Academic Press. - 2002-2131.
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Bokkapitel (refereegranskat)abstract
- During the first half of the twentieth century, the industrialization of Sweden was completed. A substantial proportion of the population resided in cities. What did the life courses of these people actually look like? In this book, four researchers have studied a random sample of men and women in Gothenburg, tracing their movements through the various phases of life, and between residences, working places and occupations. It is an account of important events in the lives of ordinary people during a period when much of the modern society was formed.
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| 4. |
- Karlsson, Tobias, et al.
(författare)
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Sensing abilities of embedded vertically aligned carbon nanotube forests in structural composites: From nanoscale properties to mesoscale functionalities
- 2023
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Ingår i: Composites Part B: Engineering. - : Elsevier BV. - 1359-8368 .- 1879-1069. ; 255
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, Vertically Aligned Carbon Nanotube (VACNT) forests are embedded into two different glass fibre/epoxy composite systems to study their sensing abilities to strain and temperature. Through a bottom-up approach, performing studies of the VACNT forest and its individual carbon nanotubes on the nano-, micro-, and mesoscale, the observed thermoresistive effect is determined to be due to fluctuation-assisted tunnelling, and the linear piezoresistive effect due to the intrinsic piezoresistivity of individual carbon nanotubes. The VACNT forests offer great freedom of placement into the structure and reproducibility of sensing sensitivity in both composite systems, independent of conductivity and volume fraction, producing a robust sensor to strain and temperature.
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| 5. |
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| 6. |
- Lundh, Christer, 1952, et al.
(författare)
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Labour mobility in an industrial city: Gothenburg 1923-1931
- 2011
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Ingår i: Paper for the session “Labour market issues - a micro perspective” at the Swedish Economic History Meeting, Gothenburg, 25-27 August, 2011.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 7. |
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| 8. |
- Mirza, Majd, et al.
(författare)
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Circulating fibroblast growth factor-23 is associated with fat mass and dyslipidemia in two independent cohorts of elderly individuals
- 2011
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Ingår i: Arteriosclerosis, Thrombosis and Vascular Biology. - 1079-5642 .- 1524-4636. ; 31:1, s. 219-227
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Tidskriftsartikel (refereegranskat)abstract
- Objective—Disturbances in mineral metabolism define an increased cardiovascular risk in patients with chronic kidney disease. Fibroblast growth factor-23 (FGF23) is a circulating regulator of phosphate and vitamin D metabolism and has recently been implicated as a putative pathogenic factor in cardiovascular disease. Because other members of the FGF family play a role in lipid and glucose metabolism, we hypothesized that FGF23 would associate with metabolic factors that predispose to an increased cardiovascular risk. The goal of this study was to investigate the relationship between FGF23 and metabolic cardiovascular risk factors in the community.Methods and Results—Relationships between serum FGF23 and body mass index (BMI), waist circumference, waist-to-hip ratio, serum lipids, and fat mass were examined in 2 community-based, cross-sectional cohorts of elderly whites (Osteoporotic Fractures in Men Study: 964 men aged 75±3.2; Prospective Investigation of the Vasculature in Uppsala Seniors study: 946 men and women aged 70). In both cohorts, FGF23 associated negatively with high-density lipoprotein and apolipoprotein A1 (7% to 21% decrease per 1-SD increase in log FGF23; P<0.01) and positively with triglycerides (11% to 14% per 1-SD increase in log FGF23; P<0.01). A 1-SD increase in log FGF23 was associated with a 7% to 20% increase in BMI, waist circumference, and waist-to-hip ratio and a 7% to 18% increase in trunk and total body fat mass (P<0.01) as determined by whole-body dual x-ray absorptiometry. FGF23 levels were higher in subjects with the metabolic syndrome compared with those without (46.4 versus 41.2 pg/mL; P<0.05) and associated with an increased risk of having the metabolic syndrome (OR per 1-SD increase in log FGF23, 1.21; 95% CI, 1.04 to 1.40; P<0.05).Conclusion—We report for the first time on associations between circulating FGF23, fat mass, and adverse lipid metabolism resembling the metabolic syndrome, potentially representing a novel pathway(s) linking high FGF23 to an increased cardiovascular risk.
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| 9. |
- Ståhle, Alexander, et al.
(författare)
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Designguide för Smarta gator
- 2022
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Bok (övrigt vetenskapligt/konstnärligt)abstract
- Designguiden för smarta gator konkretiserar hur de fyra megatrenderna urbanisering, digitalisering, samhällsförändringar och miljöförändringar leder till nya krav och utformningsprinciper för framtidens gator. Guiden är tänkt att fungera som en inspiration och ett underlag för att förnya svensk gatupolicy på nationell, regional och kommunal nivå.Guiden innehåller utöver en inledning följande kapitel: en historisk tillbakablick (gatans utveckling), gatans användning, gatans delar, gatans design, designprocessen, guidens genomförande.
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