47 resultados para Damage scenarios


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The purpose of the thesis is to generate scenarios of future purposes and of use of ships, suitable for STX Finland Cruise Oy to design and build, over a 50 year time span by applying the Delphi method and an open innovation approach in a future workshop. The scenarios were mapped out with help of two Delphi survey rounds and one future workshop. The number of participants in both surveys and the workshop was some twenty experts in each, representing various fields. On the basis of the first survey round, four different subject areas were selected for analysis: purposes for the use of ships; energy efficiency of cruises and ships; cost efficiency of sea transportation and vacation; and the views and expectations of the customers in the future. As a result of the future workshop, four different themes were established, which were studied further during the second Delphi round. The themes are future service and operation concepts; versatile uses of the space in ships; communication of environmental benefits of ships, future energy solutions and social interaction between passengers onboard. In addition to generating the scenarios, further aim of the thesis is to implement the Delphi method and workshop activity as foresight tools for STX Europe and to produce a chart of a future shipbuilding foresight community to can serve the open innovation processes in the maritime cluster as a whole.

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The effects of pulp processing on softwood fiber properties strongly influence the properties of wet and dry paper webs. Pulp strength delivery studies have provided observations that much of the strength potential of long fibered pulp is lost during brown stock fiber line operations where the pulp is merely washed and transferred to the subsequent processing stages. The objective of this work was to study the intrinsic mechanisms which maycause fiber damage in the different unit operations of modern softwood brown stock processing. The work was conducted by studying the effects of industrial machinery on pulp properties with some actions of unit operations simulated in laboratory scale devices under controlled conditions. An optical imaging system was created and used to study the orientation of fibers in the internal flows during pulp fluidization in mixers and the passage of fibers through the screen openings during screening. The qualitative changes in fibers were evaluated with existing and standardized techniques. The results showed that each process stage has its characteristic effects on fiber properties: Pulp washing and mat formation in displacement washers introduced fiber deformations especially if the fibers entering the stage were intact, but it did not decrease the pulp strength properties. However, storage chests and pulp transfer after displacement washers contributed to strength deterioration. Pulp screening proved to be quite gentle, having the potential of slightly evening out fiber deformations from very deformed pulps and vice versa inflicting a marginal increase in the deformation indices if the fibers were previously intact. Pulp mixing in fluidizing industrial mixers did not have detrimental effects on pulp strength and had the potential of slightly evening out the deformations, provided that the intensity of fluidization was high enough to allow fiber orientation with the flow and that the time of mixing was short. The chemical and mechanical actions of oxygen delignification had two distinct effects on pulp properties: chemical treatment clearly reduced pulp strength with and without mechanical treatment, and the mechanical actions of process machinery introduced more conformability to pulp fibers, but did not clearly contribute to a further decrease in pulp strength. The chemical composition of fibers entering the oxygen stage was also found to affect the susceptibility of fibers to damage during oxygen delignification. Fibers with the smallest content of xylan were found to be more prone to irreversibledeformations accompanied with a lower tensile strength of the pulp. Fibers poor in glucomannan exhibited a lower fiber strength while wet after oxygen delignification as compared to the reference pulp. Pulps with the smallest lignin content on the other hand exhibited improved strength properties as compared to the references.

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Epileptic seizures are harmful to the developing brain. During epileptic seizures, overactivation of glutamate receptors (GluR) leads to neuronal degeneration, defined as excitotoxicity. The hippocampus is especially vulnerable to excitotoxic neuronal death, but its mechanism has remained incompletely known in the developing brain. Recently, signs of activation of inflammatory processes after epileptic seizures have been detected in the hippocampus. The purpose of this thesis was to study the inflammatory reaction and death mechanisms in excitoxic neurodegeneration induced by the glutamate analogue kainic acid (KA) in the developing hippocampus. Organotypic hippocampal slice cultures (OHCs), prepared from 6-7-day-old rats (P6-7) and treated with KA, served as an in vitro model. KA-induced status epilepticus in P9 and P21 rats was used as an in vivo model. The results showed that the pyramidal cell layers of the hippocampus were the most susceptible to irreversible and age-specific neurodegeneration, which occurred in the juvenile (P21), but not in the immature (P9), rat hippocampus. The primary death mechanism was necrosis as there were no significant changes in the expression of selected apoptosis markers and morphological cellular features of necrosis were found. Inflammatory response was similarly age-dependent after KA treatment as a rapid, fulminant and wide response was detected in the juvenile, but not in the immature, rat brain. An anti-inflammatory drug treatment, given before KA, was not neuroprotective in OHCs, possibly because of the timing of the treatment. In summary, the results suggest that KA induces an age-dependent inflammatory response and necrotic neurodegeneration, which may cause disturbances in hippocampal connectivity and promote epileptogenesis.

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This master's thesis examines scenarios, which can lead to a reactivity excursion due to boron dilution events in Loviisa nuclear power plant. This thesis also describes how the boron diluted slugs are modelled in the Probabilistic Risk Assessment (PRA) model. At the current model, the valuation of the reactivity risk due to boron dilution has been very conservative, and therefore the reactivity risk during an outage is as much as 9 % of Core Damage Frequency (CDF) and Large Release Frequency (LRF). The main objective of the thesis is to decrease the annual core damage and Large Release Frequency by reducing conservative assumptions in the probabilistic modelling of boron dilution events. The core behavior during boron dilution events was modelled and reported in 2011 by Fortum using three-dimensional core model of Apros. The results of these analyses were reported same year by Fortum. According to the reported results and the analyses made by StarNode visualization program, it seems that some changes could be made in the boron dilution fault trees of the PRA model. As a result, the reactivity risk was decreased to 0.7 % of the annual CDF. In the other words, the total annual CDF and LRF were decreased 8.5 % due to the changes made in the PRA model. However the analyses made by Apros include some uncertainty. The accuracy of the analyses should be validated before making these changes in the official PRA model.

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Waste incineration plants are increasingly established in China. A low heating value and high moisture content, due to a large proportion of biowaste in the municipal solid waste (MSW), can be regarded as typical characteristics of Chinese MSW. Two incineration technologies have been mainly established in China: stoker grate and circular fluidized bed (CFB). Both of them are designed to incinerate mixed MSW. However, there have been difficulties to reach the sufficient temperature in the combustion process due to the low heating value of the MSW. That is contributed to the usage of an auxiliary fossil fuel, which is often used during the whole incineration process. The objective of this study was to design alternative Waste-to-energy (WTE) scenarios for existing WTE plants with the aim to improve the material and energy efficiency as well as the feasibility of the plants. Moreover, the aim of this thesis was to find the key factors that affect to the feasibility of the scenarios. Five different WTE plants were selected as study targets. The necessary data for calculation was gained from literature as well as received from the operators of the target WTE plants. The created scenarios were based on mechanical-biological treatment (MBT) technologies, in which the produced solid recovered fuel (SRF) was fed as an auxiliary fuel into a WTE plant replacing the fossil fuel. The mechanically separated biowaste was treated either in an anaerobic digestion (AD) plant, a biodrying plant, a thermal drying plant, or a combined AD plant + thermal drying plant. An interactive excel spreadsheet based computation tool was designed to estimate the viability of the scenarios in different WTE cases. The key figures of the improved material and energy efficiency, such as additional electricity generated and avoided waste for landfill, were got as results. Furthermore, economic indicators such as annual profits (or costs), payback period, and internal rate of return (IRR) were gained as results. The results show that the AD scenario was the most profitable in most of the cases. The current heating value of MSW and the tipping fee for the received MSW appeared as the most important factor in terms of feasibility.

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In the latter days, human activities constantly increase greenhouse gases emissions in the atmosphere, which has a direct impact on a global climate warming. Finland as European Union member, developed national structural plan to promote renewable energy generation, pursuing the aspects of Directive 2009/28/EC and put it on the sharepoint. Finland is on a way of enhancing national security of energy supply, increasing diversity of the energy mix. There are plenty significant objectives to develop onshore and offshore wind energy generation in country for a next few decades, as well as another renewable energy sources. To predict the future changes, there are a lot of scenario methods developed and adapted to energy industry. The Master’s thesis explored “Fuzzy cognitive maps” approach in scenarios developing, which captures expert’s knowledge in a graphical manner and using these captures for a raw scenarios testing and refinement. There were prospects of Finnish wind energy development for the year of 2030 considered, with aid of FCM technique. Five positive raw scenarios were developed and three of them tested against integrated expert’s map of knowledge, using graphical simulation. The study provides robust scenarios out of the preliminary defined, as outcome, assuming the impact of results, taken after simulation. The thesis was conducted in such way, that there will be possibilities to use existing knowledge captures from expert panel, to test and deploy different sets of scenarios regarding to Finnish wind energy development.

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Bumblebees are a very essential group of pollinating insects, but their populations have declined drastically during the past decades. We need to understand why their numbers are decreasing and what can be done to reverse this trend. Climate change-related phenomena, such as changes in the overwintering temperatures and spring conditions, are among the most prominent threats to bumblebees. Queens have a special role in the lifecycle of bumblebees because they overwinter and start new colonies the next year. Their successful performance: survival, overwintering ability, longevity, immune competence, and nest establishing capability in spring, is highly important for bumblebee populations. However, the effects of climate change on bumblebee queen performance remain unknown. The main objective of this thesis was to assess how temperature affects the performance of bumblebee queens during and after overwintering. The effects of warm temperature predicted by climate change scenarios on queen survival and stress-tolerance were studied by a four-month artificial diapause of bumblebee queens at two temperatures (9°C and 1.8°C). Bumblebee colonies were also reared in a laboratory and factors affecting colony characteristics were examined. In addition, queen performance during spring was studied in a starvation experiment using two temperatures (15°C as normal; 24°C as warmer than average) and queens collected from nature right after their emergence. My research revealed how temperature affects queen performance, and queen size was found to be an important factor determining the direction of some of these effects. We found a 0.4g weight threshold for bumblebee queens to be able to survive overwintering. In addition, during mild winters, larger queens have a higher chance than smaller ones to survive through winter and also to cope with immunological stresses after overwintering. During cold conditions, which are normal in the current climatic situation, this advantage disappears. In the spring starvation experiment, the starved queens survived approximately eight days longer in 15°C than in 24°C, which means that starvation risk rises significantly with increasing spring temperature, in a situation where food is scarce due to for example frost damage or asynchrony between bumblebees and their important food plants. These results could mean that in the future climate, larger queens are better able to survive the winter, initiate their nests and start rearing their offspring. This may be problematic, because I also detected two alternative strategies of colony development that differ between large and small queens; larger queens start to lay eggs earlier at nest initiation, their colonies mature later, they produce more workers, and they have a more strongly male biased sex allocation compared with smaller queens. If larger queens have a greater change of producing offspring after a mild winter, this could lead to a significant decline in the total production of new queens at a population level. Thus, it seems that queen size could act as one mechanism regulating the population level outcomes in different temperatures. The new information presented in my thesis reinforces that basic research, monitoring, and local species conservation of bumblebees both in Finland and globally must be increased to ensure that this highly important pollinator group survives in the face of climate change.