Old and coarse trees implement vital functions for humans, animals, and nature. Swedish forests have for a long time been affected by man, which affects the trees’ age and size distribution. The proportion of old-trees is currently low and it is desirable to increase it. Using data on sample trees’ from the Swedish National Forest Inventory, I analysed old-tree distribution in different land-use types and age-distribution, as well as coarse trees in Östergötland under the years 1983-2017. Furthermore, I analysed the sample trees form the year 1927 to compare with the sample trees in period 1983-2017. The defined age of an old-tree 5% older trees in the data was used while the coarse trees were defined by “miljömålets” definition. The tree sample data involved Pinus sylvestris, Picea abies, Quercus robur, Populus tremula, and Alnus glutinosa. Their occurrence in four different land-use types were considered: (i) productive woodland, (ii) arable land and natural pasture, (iii) mountains and other wastelands, and (iv) peatland. The results shows that a higher percentage of old and coarse trees occur in (i) productive woodland during the years 1983-2017. The coarse trees had similar distribution in the different land-use types during the years 1983-2017 and over time. Comparison with 1927 showed that the number of old-trees has decreased while the coarse trees had increased. Thus, the land-use types, except (i), do not constitute a reservoir for old and coarse trees and that the coarse trees individuals overlap with the old trees. / Gamla träd och grova träd utför livsviktiga funktioner för både människa, djur och natur. Sveriges skogar har länge påverkats av människan och det har påverkat trädens ålders- och storleksfördelning. Idag är andelen gamla träd låg i Sverige och det manifesteras åtgärder för att öka andelen äldre och grövre träd i skogarna. Genom att använda riksskogstaxeringens provträdsdata kan vi veta hur gamla och grova träd är fördelade bland marktyper. Denna studie undersökte hur gamla provträd var fördelade bland marktyper och deras åldersfördelning, samt motsvarande för grova träd i Östergötlands län. Dessutom jämfördes perioderna 1983–2017 och 1927. Gamla träd utgjorde per definition 5% av de äldre träden, medan grova träd definierades utifrån miljömålet levande skogar. Provträdsdata var på trädslagen; Pinus sylvestris, Picea abies, Quercus robur, Populus tremula och Alnus glutinosa som fanns inom marktyperna; (i) produktiv skogsmark, (ii) åkermark och naturbete, (iii) berg och vissa andra impediment, och (iv) myr. Resultaten visar att en hög andel gamla liksom grova provträd fanns inom produktiv skogsmark i Östergötlands län under 1983–2017. Bland marktyperna hade de grova provträd liknande odds och en liknande grovleksfördelning för båda perioderna. Dock sedan 1927 har andelen gamla träd minskat, medan andelen grova provträd har ökat. Därmed utgör marktyperna utöver (i) inte en reservoar för gamla som grova träd samt att de grova träden kan spegla de gamla trädens förekomst.

Concrete is one of the world’s most common construction materials and is composed of 70-80 % stone material. Today crushed stone is used as aggregate in concrete in order to replace natural aggregates due to strong environmental reasons. Stone crushing yields flaky material and in this thesis studies are made on the flaky particle shape and how it influence properties of concrete such as workability, rheology and strength. The concrete recipes used in this thesis have fixed values, the only variable is the flakiness of the crushed stone. Flakiness is varied between 0 %, 17 %, 50 %, and 100 % in turn for the individual size fractions 2-8 mm, 8-10 mm, 10–12.5 mm, and 12.5–16 mm. By using Swedish and European standards one determines flakiness index, packing factor, slump test, Thaulow tester, compression strength and flexural strength. The Bingham model is applied with the use of a viscometer to determine the concretes rheological properties such as plastic viscosity and yield stress. For the individual size fraction 12.5-16 mm a flow analysis is performed in an L-box to study how the particles are orientated with the flow direction, and how this influences the strength and crack length. Results show that the loose packing factor decreases with increased flakiness for all individual size fractions. Fractions 2-8 mm and 8-10 mm need a small increase in super plasticizer with increased flakiness to achieve 200 mm slump. The larger individual size fractions do not show any increase in super plasticizer regarding this matter. The Thaulow tester indicates constant values with increased flakiness for all individual size fractions except 2-8 mm were a weak increase is observed. Values of the plastic viscosity are indicated unchanged as the flakiness index is increased for all individual size fractions except 2-8 mm that slightly increase for 100 % flakiness. The yield stress behaves unchanged with increased flakiness for all individual size fractions except 12.5-16 mm which significantly decrease for 100 % flakiness. When the concrete flows in the L-box an image analysis concludes that the larger amounts of flaky particles are orientated with the flow direction. The crack length increases with higher flakiness for fraction 12.5-16 mm but this does not lead to an increase in strength. Flexural strength increase with higher flakiness, this is clearly observed for the two largest individual size fractions. Compressive strength is indicated to be independent of flakiness and is approximately constant for all individual size fractions except individual size fraction 12.5-16 mm that indicates an increase. High flakiness on cone crushed granite rock in size fraction 8-16 mm from the bedrock in Enhörna is not regarded as disadvantageous for concrete manufacturing, as it shows good values in workability, rheology and strength. / Betong är ett av världens vanligaste byggmaterial och består av ungefär 70-80 % stenmaterial. Idag används krossten som ballast i betong för att ersätta naturgrus av starka miljöskäl. Stenkrossning ger upphov till flisigt material och i detta arbete studeras den flisiga kornformen och hur den påverkar betongens egenskaper inom arbetbarhet, reologi och hållfasthet. Blandningsreceptet har fixerade värden och den enda variabeln som varierar i arbetet är flisigheten på krosstenen. Flisigheten varieras mellan 0 %, 17 %, 50 % och 100 % i tur och ordning för delfraktionerna 2-8 mm, 8-10 mm, 10–12.5 mm, och 12.5–16 mm. Genom att använda svenska och europeiska standarder bestäms flisighetsindex, packningsindex, sättmått, omformningstal, tryckhållfasthet och böjdraghållfasthet. Bingham modellen tillämpas för att med hjälp av en viskometer bestämma betongens reologiska egenskaper som plastisk viskositet och flytgränsspänning. För delfraktionen 12.5-16 mm utförs även flödesanalys med hjälp av en L-låda för att studera hur partiklar orienterar sig med flödesriktningen, och hur detta påverkar hållfastheten och spricklängden. Resultat visar att den lösa packningsgraden sjunker med ökad flisighet för samtliga delfraktioner. Fraktionerna 2-8 mm och 8-10 mm kräver en liten ökning av plasticerarmängden med ökad flisighet för att uppnå sättmått 200 mm. De större delfraktionerna visar dock ingen ökning av plasticerarmängd i detta avseende. Omformningstalet är i princip konstant med ökad flisighet för samtliga fraktioner förutom för 2-8 mm fraktionen där en svag ökning kan dokumenteras. Den plastiska viskositeten indikeras oförändrad då flisighetsindex ökar för samtliga delfraktioner förutom 8-10 mm fraktionen som ökar en aning vid 100 % flisighet. Flytgränsspänningen beter sig konstant med ökad flisighet för samtliga delfraktioner förutom 12.5-16 mm som signifikant sjunker för 100 % flisighet. När betongen flyter i L-lådan dras slutsatsen från bildanalys att den största delen flisiga partiklar orienterar sig med flödesriktningen. Spricklängden ökar med större flisighet för fraktionen 12.5-16 mm men detta visar ingen ökning i hållfastheten. Böjdraghållfastheten blir högre med ökad flisighet, denna trend visas tydligast av de två största delfraktionerna Tryckhållfastheten kan indikeras vara oberoende av flisighet och är ungefär konstant för samtliga delfraktioner förutom delfraktion 12.5-16 mm som indikerar en ökning. Hög flisighet på konkrossad granitsten fraktion 8-16 mm från bergtäkten i Enhörna anses inte vara ogynnsam för betongtillverkningen, då den ger goda värden på arbetbarhet, reologi och hållfasthet.

Over the last decades, there has been much attention on air quality, especially in urban environments. A significant factor effecting the air quality in the urban environment is airborne particulate matter (PM). Long-term exposure to PM causes increased risk for heart disease, decreased lung function, exacerbation of asthma, and lung cancer. Therefore, many countries have implemented exposure limits to the concentration of ambient PM in the urban environments. The toxicity of PM is dependent on several factors such as chemical composition, shape, adsorbed materials, and particle sizes (usually divided in ultrafine, fine and coarse particles). However, the relationship between different PM properties and developing health hazards are not clear. Therefore, further studies to investigate different properties of PM may contribute to understanding the influence of PM on human health.  In the present work, different novel methods to investigate sampled airborne PM and to investigate potential health effects have been used to increase the knowledge regarding street and wear particles. In study I, a sampling plan involving collecting one filter from Tapered Element Oscillating Microbalance (TEOM) monitoring stations used for Environmental monitoring each month for 20 months were developed. Particles on the filters were extracted into a suspension. TEOM particles were then studied with respect to constituents and variables that reflect their toxicity. The constituent and toxicity was found to be spatial and seasonal dependent. As a follow-up, in study II, TEOM filters from three geographical different cities were collected once a month for a year. The variation in particle mass measured with TEOM monitor, cadmium and lead contents, as well as endotoxin levels between locations and time points over the year was studied. The correlation between studied variables and biological effect was investigated. The results show that the concentration of metals and endotoxin in TEOM particles have no relationship to particle mass, while endotoxin levels coincided with pro-inflammatory response. These studies show that results from analyzing different variables on obtained particles from TEOM filters in combination with information about the ambient particle concentration, could be helpful in the evaluation of differences in the risk of breathing air at various locations.  The dominant road traffic particle sources are wear particles from the road and tyre interface, and from vehicle brake pads. The particle concentrations are highest in cities with high traffic amounts and a high frequency of braking. There are a few cell studies that have investigated the toxicological and biological effect of these wear particles, but there is a lack of knowledge regarding their effect on tissue level. Furthermore, the knowledge about importance of rock materials in pavement is deficient. To mitigate these knowledge gaps, the effect of different wear particles from pavement and brake pad were tested using a model with isolated perfused rat lungs in study III. The wear particles from the pavement showed a significant decrease of tidal volume compared to unexposed controls. The largest effect were found with quartzite stone material. Wear particles from brakes instead showed a larger effect on released proinflammatory cytokines. The study shows that the toxic effect on lungs exposed to airborne particles can be investigated using repetitive measurements of tidal volume. Furthermore, the study shows that the choice of rock material in road pavements has the potential to affect the toxicity of road wear particles. This should be considered in environments where the concentrations and exposures are high. The brake particles showed a different effect than stone particles, indicating the need to differentiate wear particles from different sources in relation to health effects. In summary, the present work have investigated different aspects of airborne particles collected from streets as well as generated wear particles. These indicate different important aspects of the particles that may be of importance to better understand their health effects.

No description available.

One of the major cost factors in mechanical pulp production is the electrical energy input. Much of the research in this field has therefore been devoted to an understanding of the mechanisms in the refining process and, consequently, to find ways of reducing the electrical energy consumption. Shear and compression are probably the main types of fibre deformation occurring in refiners for collapsing and fibrillating the fibres into a suitable pulp. In current refiners, the repeated mechanical action of the bars on the fibres consumes large amounts of energy in a treatment of mechanical fibres that is almost random. Fundamental studies of the deformation of wood have indicated that a combination of shearing and compression forces is highly beneficial in terms of fibre deformation with a low energy demand. Pure compression is able to permanently deform the fibre but requires a substantial amount of work, while pure shearing, although being much less energy demanding, does not lead to any permanent deformations. A more suitable application of the shear and compression forces on the wood fibres during the refining process could be a way to develop fibres at a lower energy demand. These ideas have been studied in this work trying to find new ways of saving energy in the mechanical pulping process. The first paper in this thesis discusses the way of producing wood shavings and the introduction of shear/compression deformations in these, as well as the potential benefits of using them instead of wood chips as raw material for TMP production. With the shaving process, high deformations in the wood cells were achieved by the shear and compression forces. This led to energy savings of about 25% at a given tensile index, when compared to traditional chips. The quality of the pulp produced from wood shavings was found to be better than that of the pulp produced from wood chips, when it came to strength properties (except for tear index) and optical properties at comparable energy levels. Another way of reducing energy consumption in refining involving a limited shear combined with compression forces for the mechanical treatment of both wood chips and coarse fibres was also studied. This work shows that such a kind of treatment resulted in a high degree of fibre collapse at low energy demands. The thick-walled transition fibres could even be permanently deformed. Furthermore, refining trials, utilising shear and compression pre-treated chips, showed that the strength properties, except for tear index, along with the optical properties of a TMP could be improved and the electrical energy consumed could be reduced by approx. 100 kWh/tonne, when compared to untreated chips. The results from the pilot trials described in this work could be used as a starting point for further implementation in the industry, in order to identify the most efficient way of producing mechanical pulp with a lower consumption of electrical energy. / QC 20101119

The ecological significance of coarse woody debris (CWD) is usually highlighted in forests where CWD constitutes much of an ecosystem's carbon (C) source and stores. However, a unique addition of CWD is occurring in semi-deserts for which there is no ecological analog. To stem catastrophic wildfires and create firebreaks, whole Juniperus osteosperma (Torr.) and Pinus edulis (Engelm.) trees are being mechanically shredded into CWD fragments and deposited on soils previously exposed to decades of tree-induced changes that encourage "tree islands of fertility." To investigate consequences of CWD on C and nitrogen (N) cycling, we evaluated microbial metabolic activity and N transformation rates in Juniperus and Pinus surface and subsurface soils that were either shredded or left untreated. We sampled three categories of tree cover on over 40 tree cover encroachment sites. Tree cover categories (LOW = 0-15%, MID ≥ 15-45%, HIGH ≥ 45%) were used to indicate tree island development at time of treatment. In conjunction with our microbial measurements, we evaluated the frequency of three exotic grasses, and thirty-five native perennial grasses to identify links between belowground and aboveground processes. The addition of CWD increased microbial biomass by almost two-fold and increased microbial efficiency, measured as the microbial quotient, at LOW Juniperus cover. C mineralization was enhanced by CWD only in Pinus soils at the edge of tree canopies. The addition of CWD had little impact on microbial activity in subsurface soils. CWD enhanced the availability of dissolved organic C (DOC) and phosphorus (P) but tended to decrease the overall quality of labile DOC, measured as the ratio of soil microbial biomass to DOC. This suggested that the increase in DOC alone or other environmental factors novel to CWD additions lead to the increase in biomass and efficiency. P concentrations were consistently higher following CWD additions for all encroachment levels. The CWD additions decreased N mineralization and nitrification in Juniperus and Pinus soils at LOW and MID tree cover but only in surface soils, suggesting that less inorganic N was available to establishing or residual plants. The frequency of native perennial grasses, especially Elymus elymoides (Raf.), was at least 65% higher under CWD additions for all categories of tree cover, while the frequencies of exotic annual and perennial grasses were not impacted by CWD. The frequency of all perennial grasses ranged from 10-27%. Our results suggest that CWD enhanced microbial activity even when the quality of C substrates declined requiring microbes to immobilize more N. The reduction in inorganic N may promote the establishment and growth of native perennial grasses. Ultimately, the addition of CWD improved soil conditions for microbes in tree islands of fertility.

A series of recent excavations on the 2nd Century AD Antonine frontier forts of the Midland Scottish valley, have produced results which suggest that the army was making its own pottery on an appreciable scale. This was at a time when pottery production was thought to have moved almost exclusively into civilian hands. The possible local ware groups identified by the excavations were largely independent of firm source indicators such as kiln and waster material and the number of available samples was often-small. A program of Neutron Activation and Thin Section petrological analyses was undertaken along with an investigation into Textural Analysis, a facet of the Petrological toolkit. The aim was both to define the site ware groups and a group of specialist vessels thought to be local to Scotland, the Mortaria, and to make statements as to their provenance. Although the Mortaria analysis was limited by problems of sample group size and availability, by improving the objectivity of the statistical handling of the derived data sets and developing methods for the high level study of textural data, the site ware groups were defined successfully at both the "intrall and "inter" site levels. The analyses also furnished interpretations as to the mode and nature of the site production schemes. Through the full analysis of' site Daub samples linked to more traditional provenancing techniques, in all but one case the ware groups could be assigned to the source sites, where contrasting production modes could be identified with military as opposed to civilian production. / SERC

Accelerating the simulation of turbulence to stationarity is a critical challenge in various engineering applications. This study presents an innovative equation-free multiscale approach combined with a machine learning technique to address this challenge in the context of the one-dimensional stochastic Burgers' equation, a widely used toy model for turbulence. We employ an encoder-decoder recurrent neural network to perform super-resolution reconstruction of the velocity field from lower-dimensional energy spectrum data, enabling seamless transitions between fine and coarse levels of description. The proposed multiscale-machine learning framework significantly accelerates the computation of the statistically stationary turbulent Burgers' velocity field, achieving up to 442 times faster wall clock time compared to direct numerical simulation, while maintaining three-digit accuracy in the velocity field. Our findings demonstrate the potential of integrating equation-free multiscale methods with machine learning methods to efficiently simulate stochastic partial differential equations and highlight the possibility of using this approach to simulate stochastic systems in other engineering domains. / Master of Science / In many practical engineering problems, simulating turbulence can be computationally expensive and time-consuming. This research explores an innovative method to accelerate these simulations using a combination of equation-free multiscale techniques and deep learning. Multiscale methods allow researchers to simulate the behavior of a system at a coarser scale, even when the specific equations describing its evolution are only available for a finer scale. This can be particularly helpful when there is a notable difference in the time scales between the coarser and finer scales of a system. The ``equation-free approach multiscale method coarse projective integration" can then be used to speed up the simulations of the system's evolution. Turbulence is an ideal candidate for this approach since it can be argued that it evolves to a statistically steady state on two different time scales. Over the course of evolution, the shape of the energy spectrum (the coarse scale) changes slowly, while the velocity field (the fine scale) fluctuates rapidly. However, applying this multiscale framework to turbulence simulations has been challenging due to the lack of a method for reconstructing the velocity field from the lower-dimensional energy spectrum data. This is necessary for moving between the two levels of description in the multiscale simulation framework. In this study, we tackled this challenge by employing a deep neural network model called an encoder-decoder sequence-to-sequence architecture. The model was used to capture and learn the conversions between the structure of the velocity field and the energy spectrum for the one-dimensional stochastic Burgers' equation, a simplified model of turbulence. By combining multiscale techniques with deep learning, we were able to achieve a much faster and more efficient simulation of the turbulent Burgers' velocity field. The findings of this study demonstrated that this novel approach could recover the final steady-state turbulent Burgers' velocity field up to 442 times faster than the traditional direct numerical simulations, while maintaining a high level of accuracy. This breakthrough has the potential to significantly improve the efficiency of turbulence simulations in a variety of engineering applications, making it easier to study and understand these complex phenomena.

This study investigates the use of polyvinyl chloride (PVC) as a partial substitute of natural aggregates in concrete as fine and coarse aggregates. Concrete was prepared by replacing natural aggregates with equal volume of grinded PVC, with volume replacement ratio as 10%, 50% for fine and then 10% and 50% for coarse aggregates. Experiments were performed to investigate the wet density, workability (measured by slump test), compressive strength, elastic modulus, and water absorption of concrete. After checking the particle distribution (sieve analysis), wet density, workability, and compressive strength, since compressive strength of coarse PVC concrete was much less than that of the reference concrete it was decided to continue the investigation using only the fine partial replacements. The results showed that the wet density of concrete gradually decreased with the increase of PVC content, and workability increased with the increase of PVC. Compressive strength decreased by 13 to 20% for fine PVC and 25 to 31% for coarse PVC concrete, as PVC content increased. Also, it was realized that with the increase of PVC content, elastic modulus decreased by 8.7% for 10% fine PVC while 30% for 50% coarse PVC concrete, and water absorption decreased by 27% for 10% fine PVC concrete and 36% for the 50% fine PVC. It is not advisable to replace aggregates with PVC for achieving reference strength of 40 MPa with water to cement ratio. After studying many probabilities of using the PVC aggregates, it was decided to work on the possible maximum and minimum percentages of substitution, where it was chosen to be 10 and 50%.

No description available.