| 881. |
- Nyström, Ulrika, 1981
(författare)
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Modelling of Concrete Structures Subjected to Blast and Fragment Loading
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Betong är tack vare sin låga kostnad och sitt stora användningsområde ett av de mest använda byggmaterialen i modern tid. Dess stora energiabsorberande förmåga vid höga tryck, samt det sega beteende betongkonstruktioner har vid väl utformad armering, gör betongen också lämplig i skyddande konstruktioner. Responsen hos konstruktioner utsatta för extrem dynamisk belastning, så som stötvågs- och splitterbelastning, är dock förknippad med hög komplexitet och trots många år av forskning världen över är de fenomen som uppstår ännu inte helt klarlagda.Med målsättningen att öka kunskapen om betongkonstruktioners respons vid stötvågs- och splitterbelastning har litteraturstudier, teoretiska analyser och numeriska simuleringar använts på ett iterativt sätt. Den teoretiska grunden för betongmaterialets beteende, karaktärisering av stötvågs- och splitterlaster, lasternas verkan på betongkonstruktioner och dynamiska aspekter på vågpropagering behandlas i sammanläggningsdelen i denna avhandling. Därtill presenteras två numeriska studier. Den första numeriska studien var en jämförande studie av vilken relativ inverkan som tillsättning av stålfibrer i betong har på dess motståndsförmåga mot projektilinträngning. Det kunde konstateras att inträngningsdjupet var relativt opåverkat av fibertillsättningen medan kraterstorleken, på både fram och baksidan av den beskjutna kroppen, minskade. I den andra studien undersöktes responsen hos en armerad betongväggsstrimla vid kombinerad belastning av stötvåg och splitter. Det kunde konstateras att den totala skadan i väggelementet var starkt relaterat till skadan orsakad av enbart splitterbelastningen. Vidare framgick att väggstrimlans mittnedböjning var större för det kombinerade lastfallet än för den sammanlagda nedböjningen orsakad av stötvågs- respektive splitterbelastningarna separat. Detta tyder på en synergieffekt för de kombinerade lasterna. En tredje numerisk studie har utförts inom ramen för det presenterade arbetet. I denna studie har armeringens inverkan på betongens motståndsförmåga vid projektilbeskjutning undersökts. Slutsatsen drogs att armering kan ha viss betydelse för detta motstånd förutsatt att armeringen är lämpligt inlagd.I avhandlingen presenteras även en ny materialmodell (CDPM2) för dynamiskt belastad betong. Modellen har visat god förmåga att beskriva responsen vid ett stort antal lastfall, statiska så väl som dynamiska. I utvärdering av modellen har det visats att genom vissa modifieringar skulle modellens förmåga att beskriva responsen vid stora dynamiska laster kunna förbättras. Vissa riktlinjer för möjliga modifieringar har presenterats, men implementeringen och den vidare utvärderingen av dessa är inte en del av det presenterade arbetet.
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| 882. |
- Ohlauson, Cecilia, et al.
(författare)
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Short-term effects of medetomidine on photosynthesis and protein synthesis in periphyton, epipsammon and plankton communities in relation to predicted environmental concentrations
- 2012
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Ingår i: Biofouling. - : Informa UK Limited. - 0892-7014 .- 1029-2454. ; 28:5, s. 491-499
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Tidskriftsartikel (refereegranskat)abstract
- Medetomidine is a new antifouling substance, highly effective against barnacles. As part of a thorough ecotoxicological evaluation of medetomidine, its short-term effects on algal and bacterial communities were investigated and environmental concentrations were predicted with the MAMPEC model. Photosynthesis and bacterial protein synthesis for three marine communities, viz. periphyton, epipsammon and plankton were used as effect indicators, and compared with the predicted environmental concentrations (PECs). The plankton community showed a significant decrease in photosynthetic activity of 16% at 2 mg l(-1) of medetomidine, which was the only significant effect observed. PECs were estimated for a harbor, shipping lane and marina environment using three different model scenarios (MAMPEC default, Baltic and OECD scenarios). The highest PEC of 57 ng l(-1), generated for a marina with the Baltic scenario, was at least 10,000-fold lower than the concentration that significantly decreased photosynthetic activity. It is concluded that medetomidine does not cause any acute toxic effects on bacterial protein synthesis and only small acute effects on photosynthesis at high concentrations in marine microbial communities. It is also concluded that the hazard from medetomidine on these processes is low since the effect levels are much lower than the highest PEC.
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| 883. |
- Ohtonen, O., et al.
(författare)
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EFFECT OF 20 KM SIMULATED RACE LOAD ON PROPULSIVE FORCES DURING SKI SKATING
- 2020
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Ingår i: Karczewska-Lindinger, M., Hakkarainen, A., Linnamo, V., Lindinger, S. (2020) (Eds), Science and Skiing VIII, University of Jyväskylä (publisher), Jyväskylä, Finland, ISBN 978-951-39-8077-1, pp 202. - Jyväskylä, Finland : University of Jyväskylä. - 9789513980771
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Bokkapitel (refereegranskat)
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| 884. |
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| 885. |
- Ojha, Hemant R., et al.
(författare)
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Policy without politics: technocratic control of climate change adaptation policy making in Nepal
- 2016
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Ingår i: Climate Policy. - : Informa UK Limited. - 1469-3062 .- 1752-7457. ; 16:4, s. 415-433
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Tidskriftsartikel (refereegranskat)abstract
- As developing countries around the world formulate policies to address climate change, concerns remain as to whether the voices of those most exposed to climate risk are represented in those policies. Developing countries face significant challenges for contextualizing global-scale scientific research into national political dynamics and downscaling global frameworks to sub-national levels, where the most affected are presumed to live. This article critiques the ways in which the politics of representation and climate science are framed and pursued in the process of climate policy development, and contributes to an understanding of the relative effectiveness of globally framed, generic policy mechanisms in vulnerable and politically volatile contexts. Based on this analysis, it also outlines opportunities for the possibility of improving climate policy processes to contest technocratic framing and generic international adaptation solutions.
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| 886. |
- Oliveira, Dinis, 1991, et al.
(författare)
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Effect of ship hull form on the resistance penalty from biofouling
- 2018
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Ingår i: Biofouling. - : Informa UK Limited. - 0892-7014 .- 1029-2454. ; 34, s. 262-272
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Tidskriftsartikel (refereegranskat)abstract
- © 2018 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group. Hull biofouling is a well-known problem for the shipping industry, leading to increased resistance and fuel consumption. Considering that the effects of hull form on resistance are known to be higher for a less slender hull, it is hypothesised in this paper that the effect of biofouling roughness on resistance is also dependent on the hull form. To test this hypothesis, previously reported full-scale numerical results on a containership are re-analysed. Form effects on roughness penalties, corresponding to K ΔCT =0.058±0.025, are observed at a low speed (19 knots, Re s =2.29×10 9 ), which are however cancelled out by traditionally neglected roughness effects on wave-making resistance at a higher speed (24 knots, Re s =2.89×10 9 ). It is concluded that hull form effects on biofouling penalties can be significant at low speeds, though not generalisable for higher speeds, namely when wave-making resistance corresponds to≥29% of total resistance.
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| 887. |
- Oliveira, Dinis, 1991, et al.
(författare)
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HullMASTER – An Interactive Tool to Calculate Economic and Societal Costs and Benefits of Ship Hull Maintenance
- 2021
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Ingår i: Hull Performance & Insight Conference (HullPIC) Home Page. - : Hull Performance & Insight Conference (HullPIC).
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Konferensbidrag (refereegranskat)abstract
- Through cross-disciplinary research a novel interactive tool has been developed, HullMASTER, which enables shipowners, operators, and authorities in the Baltic Sea region to make evidence-based decisions on strategies and policies related to ship hull maintenance. This novel tool is deployed as a standalone app (source code in MATLAB). Modelling is based on cost-effective approximate prediction methods (Granville method), as well as on empirical fouling data. Validation of HullMASTER predictions for hull-and-propeller performance shows ~80% agreement against nearly 40 vessel-years of performance data (fleet of 9 vessels). Further, three types of hull coating were compared in a demonstration case: a copper-based antifouling coating, a biocide-free foul-release coating, and an inert abrasion-resistant coating. In this demonstration, the foul-release coating is shown to be the most sustainable alternative for a 10,000-DWT cargo ship in terms of pressure on the environment and health. These societal savings are aligned with potential economic savings for the shipping operator.
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| 888. |
- Oliveira, Marta Bastos, et al.
(författare)
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Expression of arthropod distal limb-patterning genes in the onychophoran Euperipatoides kanangrensis
- 2014
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Ingår i: Development, Genes and Evolution. - : Springer Science and Business Media LLC. - 0949-944X .- 1432-041X. ; 224:2, s. 87-96
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Tidskriftsartikel (refereegranskat)abstract
- A current hypothesis states that the ancestral limb of arthropods is composed of only two segments. The proximal segment represents the main part of the modern leg, and the distal segment represents the tarsus and claw of the modern leg. If the distal part of the limb is an ancestral feature, one would expect conserved regulatory gene networks acting in distal limb development in all arthropods and possibly even their sister group, the onychophorans. We investigated the expression patterns of six genes known to function during insect distal limb development in the onychophoran Euperipatoides kanangrensis, i.e., clawless (cll), aristaless (al), spineless (ss), zinc finger homeodomain 2 (zfh2), rotund (rn), and Lim1. We find that all investigated genes are expressed in at least some of the onychophoran limbs. The expression patterns of most of these genes, however, display crucial differences to the known insect patterns. The results of this study question the hypothesis of conserved distal limb evolution in arthropods and highlight the need for further studies on arthropod limb development.
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| 889. |
- Olsson, Alexander, et al.
(författare)
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Potential for carbon sequestration and mitigation of climate change by irrigation of grasslands
- 2014
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Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 136, s. 1145-1154
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Tidskriftsartikel (refereegranskat)abstract
- The climate change mitigation potential of irrigation powered by a photovoltaic water pumping system (PVWPS) to restore degraded grasslands has been investigated using the Intergovernmental Panel on Climate Change (IPCC) 2006 Guidelines for National Greenhouse Gas Inventories for Agriculture, Forestry and Other Land Use. The purpose of this study is to develop a generic and simple method to estimate the climate change mitigation benefit of a PVWPS. The possibility to develop carbon credits for the carbon offset markets has also been studied comparing carbon sequestration in grasslands to other carbon sequestration projects. The soil carbon sequestration following irrigation of the grassland is calculated as an annual increase in the soil organic carbon pool.The PVWPS can also generate an excess of electricity when irrigation is not needed and the emissions reductions due to substitution of grid electricity give additional climate change mitigation potential.The results from this study show that the carbon sequestration and emissions reductions benefits per land area using a PVWPS for irrigating grasslands are comparable to other carbon sequestration options such as switching to no-till practice. Soil carbon in irrigated grasslands is increased with over 60% relative to severely degraded grasslands and if nitrogen fixing species are introduced the increase in soil organic carbon can be almost 80%. Renewable electricity generation by the PVWPS will further increase the mitigation benefit of the system with 70-90%. When applying the methodology developed in this paper to a case in Qinghai, China, we conclude that using a PVWPS to restore degraded grasslands for increased grass production and desertification control has a climate change mitigation benefit of 148Mg (1Mg=1metricton) CO2-equivalents (CO2-eq) per hectare in a cold temperate, dry climate during a 20year process of soil organic carbon sequestration and emissions reductions. Leakage due to an increase in N2O emissions from the additional biomass production and introduction of nitrogen fixing species is included in this result. The most important conclusion from our case is that if soil carbon sequestration is lower than 24Mg CO2-eq per hectare including leakage, then the climate change mitigation benefit is larger if PV is used to produce electricity for the grid.
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| 890. |
- Olsson, Daniel, 1970-, et al.
(författare)
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Green Schools in Taiwan : Effects on Student Sustainability Consciousness
- 2019
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Ingår i: Global Environmental Change. - : Elsevier. - 0959-3780 .- 1872-9495. ; 54, s. 184-194
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Tidskriftsartikel (refereegranskat)abstract
- In recent decades, the Taiwanese government has worked actively to implement the concept of a sustainable Taiwan. As an important step in their strategy, the Ministry of Education has decided to promote the Green School Partnership Project in Taiwan (GPPT). However, academic research and critical reflection on the effects of this environmental and sustainability education initiative are lacking. Therefore, this study focuses on filling this gap by means of a nationwide generalizable effect study. The sampling allowed comparisons between the sixth, ninth, and twelfth grades in GPPT and non-GPPT schools and considered the geographic location (north, center, and south of Taiwan) as well as socio-economic area of the schools. A total of 1,741 students participated, answering a questionnaire that focused on student sustainability consciousness (SC) and its components (i.e., knowingness, attitudes, and behaviors in relation to sustainability). Data were analyzed through structural equation modeling. Our findings make an important empirical contribution, indicating that GPPT schools and non-GPPT schools have a similar effect on the SC of students, i.e. schools engaged in the GPPT do not enhance student SC. In addition, the gender gap regarding SC increased consistently with each increasing grade level, yielding higher mean values for the girls than for the boys. Furthermore, an adolescent dip occurred in the student SC, especially with regard to student sustainability behavior. Given these findings, implications for developing GPPT are discussed; this research could provide valuable informationabout the educational transformation process to enhance environmental and sustainability behavior among students in Taiwan.
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