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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
101

Inversion of SkyTEM Data Based on Geophysical Logging Results for Groundwater Exploration in Örebro, Sweden

Kindlund, Andrée January 2021 (has links)
Declining groundwater tables threatens several municipalities in Sweden which drinking water is collected from. To ensure a sound drinking water supply, the Geological Survey of Sweden has initiated a groundwater exploration plan. Airborne electromagnetic measurements have seen an uprise in hydrogeophysical projects and have a great potential to achieve high-quality models, especially when combined with drilling data. In 2018, the Geological Survey of Sweden conducted an airborne electromagnetic survey, using the SkyTEM system, in the outskirts of Örebro, Sweden. SkyTEM is a time-domain system and is the most favoured system in hydrogeophysical investigations and was developed especially with hydrogeophysical applications in mind. It is unique by being able to measure interleaved low and high moment current pulses which enables for both high resolution close to surface and increased depth of investigation. During 2019, further drilling in the area including both lithological, and geophysical logging including natural gamma and normal resistivity were carried out. High natural gamma radiation typically indicates content of clay in the rocks. The geology in the area is well explored since the 1940’s when oil was extracted from alum shale in Kvarntorp, located in the survey area. Rocks of sedimentary origin reaches approximately 80 m down until contact with bedrock. Well preserved layers of limestone, shale, alum shale and sandstone are common throughout the area. Combining SkyTEM data with borehole data increases the confidence and generates a model better reflecting the geology in the area. The AarhusInv inversion code was used to perform the modelling, developed by the HydroGeophysical Group (HGG) at Aarhus University, Denmark. Four different models along one single line were generated by using 3, 4, 6 and 30 layers for the reference model in the inversion. Horizontal constraints were applied to all models. Vertical constraints were only applied to the 30 layer model. The survey flight altitude is considered high and in combination with removal of data points being affected by noise, the maximum number of layers in the final model is limited to three. This suggests that the 3 layer model is the most representative model for this survey. The conductive shale seen in the geophysical log is visible in all models at a depth of roughly 40-60 m which is consistent with the geophysical log. No information is retrieved below the shale which concludes that the contact between the sandstone and crystalline rock is not resolved. The lack of information below a highly conductive structure is expected due to shielding effects. This study recommend to carefully assess the flight altitude at quality-control analysis during survey design.
102

Digitaliseringsprojekt för fastighetsbolag : med Eksta bostads AB

Lindeberg, Robin, David, Gullbrandsson January 2019 (has links)
No description available.
103

Sensitivity analysis of pluvial flood modelling tools for dense urban areas : A case study in Lundby-Lindholmen, Gothenburg

Eriksson, Johanna January 2020 (has links)
As a result of the global climate change, extreme precipitation is occurring more frequently which increases the risk of flooding, especially in urban areas. Urbanisation is widely discussed regarding urban flooding where an increase of impervious surfaces limits the infiltration and increases the surface runoff. Flooding events in urban areas are increasing around the world and can cause large damages on infrastructure and buildings, which makes the cities vulnerable. Urban flood models are an important tool for analysing the capacity of the drainage systems, to predict the extent of the events and to find optimal locations to implement measures to prevent damages from flooding. In this project, a sensitivity analysis in MIKE FLOOD, a coupled 1D-2D flood model developed by DHI is presented, where sewer- and surface systems are integrated. The aim with this project is to investigate how the result of a coupled flood model vary in relation to changes in input parameters. The sensitivity analysis is performed to evaluate how different parameters impact the model output in terms of water depth and variations in cost of flooded buildings, roads, rail- and tramways. The analysis is applied in a case study in Lundby-Lindholmen, Gothenburg city, Sweden. The results show that modelling without infiltration influenced the model output the most, with the largest increase both in terms of cost and water depth over the investigated area. Here the correlation between the initial water saturation and location of the applied pre-rain was highlighted. The model outputs were less sensitive to changes in surface roughness (expressed as Manning value) than without infiltration but did lead to measurable changes in surface water depth and distribution while the flood damage cost didn’t show any major changes. Additionally, the coupled flood model was evaluated in terms of handling changes in magnitudes of rain-events. Data indicates the shorter the return period, the smaller the flood propagation, as well as the flood damage cost decreases with shorter return periods. The data evaluated supports the use of this coupled model approach for shorter return periods in terms of flood propagation.
104

Photodegradation of macroplastics to microplastics : A laboratory study on common litter found in urban areas

Svedin, Jonathan January 2020 (has links)
During the last 60 years the plastic production has increased more than 190 times and plasticpollution both at sea and land is a growing issue. Every year millions of tons of plastic waste fromland reaches the oceans, but the land-based sources are diffuse. One possible source of plasticwaste and microplastics are from plastic litter in urban areas which is common all over the world.The aim with this laboratory study was to study the photodegradation patterns of macroplasticsthat is usually found as litter in urban areas to contribute with knowledge and to theunderstanding of how macroplastics degrade to microplastics. The laboratory study wasstructured around the use of ultraviolet light exposure from UVA 340 nm lamps to acceleratephotodegradations of plastics in air. The test was divided into four different time intervals: stage7 days, stage 14 days, stage 28 days, and stage 56 days to study the evolution of plasticfragmentation over time. Effect of the UV radiation and test duration were combined to derivethe equivalent real time duration. Using Luleå as a benchmark the computed equivalence were0.27 years for every seven days of UV exposure. For stage 7d, a test with different mediums(water and air) were performed to compare the degradation processes between differentenvironments. However, for the longer time intervals air was the only tested environment. Newplastic products were bought which were among the most produced types of plastic or mostcommon plastic litter. The plastics were the following: polystyrene (PS) as plastic coffee cup lid,polypropylene (PP) as chocolate wrapping, polyethylene terephthalate (PET) as plastic bottle,low- density polyethylene (PE-LD) as plastic grocery bag and cellulose acetate (CA) as cigarettefilter or butts. The analytical techniques used were a particle size and number counter, with theselected particle size interval between 4-120 μm, and a camera mounted microscope to studyshapes of microplastic particles. Before photographing the particles, the samples were filtered ona 10 μm aluminium filter. The results showed that photodegradation with UV light did in factaccelerate the degradation process even for short time intervals. Potential for fragmentation ofparticles in air was larger, due to air being a more oxidizing environment and weakening theplastics. The results implied that the degradation processes for PS is slower in water compared tothe other plastics in the same environment. In PS there was a larger amount of particles for theUV- exposed samples compared to the other plastics. This is interpreted as it has a slowerdegradation processes due to the fact when looking on the other plastics in stage w.7 (in water),the control samples have a higher particle count than for the UV exposed samples. It can beinterpreted as PS does not become as effected by the UV light while in water compared to theother plastics. Therefore, the conclusion is that the particles degraded and became smaller thanthe analysed size range (4 μm) and were therefore not detected, consequently, showing a lowerparticle count. After 56 days of UV radiation the largest amount of detected particle mass wasproduced by PP (chocolate wrapping) with 0.0143 mg/cm2 material and the least amount ofdetected particle mass in stage 56d was of PE-LD (plastic bag) with 0.00042 mg/cm2 material.Based on the comparison of the water stage and air stages together with conclusions from earlierstudies, the potential for a substantial destructive breaking of large particle are considered higherin air than in water, because the oxidation weakens the material making it less resilient tomechanical stress.
105

Ett cirkulärt samhälle med sulfidjord : Behandling och återanvändning

Höegh, Markus January 2020 (has links)
I Sverige förekommer det sura sulfatjordar som är resultatet av när sulfidrika sediment, som avsattes för 4000 – 7000 år sedan, introduceras i en oxisk miljö. Sedimenten avsattes i botten av Litorinahavet främst längs östkusten samt Mälardalen i anaeroba förhållanden där sulfider kunde bildas. När dessa sulfider kommer i kontakt med syret i atmosfären vittar sulfiderna och medför en pH sänkning. Detta påskyndas av en antropogen påverkan samt en pågående landhöjning som förekommer i Sverige. Ett lågt pH medför att toxiska metaller kan bli mobila och utlakas till miljöer där de kan medföra stora konsekvenser. I anläggningsprojekt deponeras stora volymer sulfidjordsmassor varje år, som ett resultat att de är försurande samt har en hög sättningsbenägenhet. Detta medför flera kostnader i byggprojekt för deponi, transport och nytt utfyllnadsmaterial. Som en följd motverkar detta ett cirkulärt samhälle när jordens resurser deponeras istället för att återvinnas och återanvändas. Skanska har beslutat om ett mål, att samtliga verksamhetsgrenar ska uppnå s.k. klimatneutralitet vid år 2045. Att framtida kunna återvinna och återanvända sulfidjord kan vara ett bidrag för Skanska att uppnå detta mål genom minskade transporter och återanvändande istället för att deponera sulfidjord och vid anläggningsarbeten tillföra jungfruligt material. För att neutralisera sulfidjord kan olika material användas som förhöjer jordens alkalinitet och motverkar försurningen från oxidationen. Två sådana material är bränd kalk och bioaska som är de två material som jämförs i detta arbete, för att se hur kvalitén på porvattnet samt växtetableringen påverkas av respektive tillsats. För att kontrollera sammansättningen av provattnet samt växtetableringen utfördes flera laborationer, kontroll av torrsubstans, glödförlust, lakförsök, bestämning av mängd buffert, kontroll av vattenhållningskapacitet, återväxtförsök, ämnes analys av porvatten och en beräkning för att uppskatta hur länge den behandlade sulfidjorden bör kunna buffra systemet mot syror.   Vanlig planteringsjord tillät bäst växtetablering och den obehandlade sulfidjorden var den jord som medförde sämst växtetablering. Porvattnet hade högre pH, kring neutralt, än initialt pH för den obehandlade sulfidjorden som var kring pH 4,5. Flera ämnen återfanns i lägre halter i porvattnet för sulfidjorden som har behandlats jämfört med den obehandlade, med vissa variationer. Porvattnet i sulfidjorden som behandlats med bioaska hade högre halter av flera ämnen jämfört med sulfidjorden som behandlats med bränd kalk, framförallt höga nivåer av arsenik samt svavel. Slutsatsen är att båda sulfidjordsblandningarna uppskattas kunna buffra systemet i mer än 10 000 år. Tillsammans med halterna i porvattnet förespråkar resultatet att det finns goda förutsättningar till att behandla sulfidjord och återanvända i olika projekt. Vidare forskning krävs till att optimera ett förhållande mellan mängd tillsatser samt mängd sulfidjord. Skanska bedöms ha goda förutsättningar till att arbeta vidare och kunna etablera en eller flera återvinningsanläggningar i landet för sulfidjord. / In Sweden there are acid sulphate soils that are the result of when sulphide rich sediments, deposited 4000 – 7000 years ago, enters an oxic environment. The sediments deposited at the bottom of the Littorina sea mainly along the east coast as well as Mälardalen in anaerobic conditions where the sulphide could precipitate. When these sulphides get in contact with the oxygen in the atmosphere weathering occurs where the reaction lowers the pH. The rate is increased due to anthropogenic actions along with land rise which occurs in Sweden. Low pH contributes the toxic metals can become mobile and leach to other environments where they could do significant damage. In construction projects, large volumes of sulphide soils are deposited at landfills annually, due to the soil being acidifying as well as the soil often have a high tendency to settle. This entails several costs in constructions projects for landfill, transport and new filling material. As a result, this offsets a circular society when natural resources are landfilled rather than reused. Skanska has decided on a goal, that all branches in their network should achieve climate neutrality by 2045. Recycling and reusage of the sulphide soil would help Skanska to achieve this goal by reduced transport and reusage of the soil instead of outsourcing for virgin material. To neutralize sulphide soils, various materials can be used as buffers that increases the alkalinity of the soil and counteract the acidification from the oxidation. Two possible materials that could achieve this is quicklime and bio-ash, which are the two materials that are compared in this work to see how the porewater quality and plant establishment are affected by the additive. In order to analyse the difference in porewater quality and plant establishment between the two additives, several laboratory works were conducted. Control of dry matter, loss of ignition, batch leaching test, determination of the amount of buffer needed to buffer the soil mixture, control of water holding capacity, growth rate test, analysis of porewater and estimation of buffer capacity. Ordinary topsoil allowed the best plant establishment and the untreated sulphide soil had the worst plant establishment. The porewater from the treated sulphide soil mixtures had a higher pH, around neutral, than the initial pH of the untreated sulphide soil, which was around pH 4,5. Several substances in the porewater had lower concentrations in the treated sulphide soil compared to the untreated, with some variation. The porewater from the soil mixture with the additive bio-ash had higher concentrations for several substances than the sulphide soil that have been treated with quicklime, especially high levels of arsenic and sulphur. The conclusions are that both sulphide soil mixtures have been estimated to be able to buffer the system for over 10 000 years. Together with the porewater properties it suggests that there are great prerequisites to treat and reuse sulphide soil. Although, a more optimum recipe for the ratio of sulphide soil, buffer and stabilizer is required. Skanska is considered to have excellent prerequisites to establish recycling facilities for sulphide soil.
106

Bestämning av evapotranspiration baserat på meteorologiska data : En utvärdering jämfört med modeller och vattenbalans

Lindqvist, Karin January 2021 (has links)
Integrerad Monitoring (IM) är ett miljöövervakningsprogram som bedriver studier i de fyra svenska avrinningsområdena Aneboda, Gårdsjön, Kindla och Gammtratten. Områdena, som är skyddade och ingår i Natura 2000, domineras av barrskog. Inom IM studeras bland annat vattenbalans, där evapotranspiration utgör en viktig men svårberäknad del. På avrinningsområdesnivå beräknas ofta evapotranspiration med hjälp av sambandet vattenbalans men denna metod medför stora osäkerheter kring hur lagring av vatten (i snö, sjöar, mark- och grundvatten) hanteras. Problematiken är särskilt stor när avdunstning beräknas för kortare tidsperioder, exempelvis på månadsbasis. Det finns istället flera ekvationer baserade på meteorologiska data som kan användas. Studiens syfte var att med hjälp av sådana ekvationer skapa möjlighet till beräkningar av evapotranspiration över olika tidsskalor. Efter en litteraturstudie valdes de två ekvationerna Penman-Monteith och Priestley-Taylor, och med platsspecifika meteorologiska data för IM-områdena beräknade de evapotranspiration som sedan skattades i jämförelse med beräkningar från andra modeller (vattenbalans, Fyris-Q och S-HYPE). Fyra hydrologiska år undersöktes och resultatet visade på stor variation mellan modellerna både på års- och månadsnivå. Vissa år genererade de liknande värden medan andra år skilde sig rejält. De två undersökta ekvationerna uppvisade liknande årliga mönster och påverkades båda mest av variabeln nettostrålning som varierar kraftigt över året. Flera faktorer har inverkan på resultatet och det finns en del osäkerheter kring anpassningar av ekvationerna. Dock kunde avvikande resultat i de flesta fall förklaras av brister i tillgängliga input-data. Om detta åtgärdas bör det därför vara möjligt att skatta evapotranspirationen även för kortare tidsperioder med hjälp av ekvationer baserade på meteorologiska data.
107

Partial Nitration/anammox process in the moving bed biofilm reactor operated at low temperatures

Sultana, Razia January 2014 (has links)
<p>QC 20140527</p>
108

Framtidens återvinningscentral / Recycling centers of the future

Christiansen, Viktor January 2022 (has links)
I dagens samhälle lever vi med stora klimatutmaningar. En av de stora problemen är hur vi lever och för oss i våran vardag. Våra konsumtionsmönster är inte ekologiskt hållbara och som resultat av det sliter vi på våran planet. Överexploateringen som länge pågått har bland annat medfört att stora mängder avfall har bildats. Utöver detta medför även denna typ av exploatering stora påfrestning på naturen. Värdefulla naturområden förstörs och resulterar i negativ påverkan på biologisk mångfald vilket i längden kan påverka ekosystemtjänster såsom vår matproduktion, naturens motståndskraft mot förändringar och skador, viktiga naturresurser, rekreationsvärdet i naturen samt alla de övriga nyttorna vi får från naturen.  Denna studie syftar till att undersöka den potentiella utvecklingen hos Södertörns Renhållningsverks återvinningscentraler relaterat till EUs avfallshierarki för att gå mot en ökad cirkulär resurshantering. Studien visar på den potentiella utvecklingen hos Södertörns Renhållningsverk och hur de denna potential kan uppnås. De olika åtgärderna som har föreslås är: A. En plats för delningsekonomi, B. Informera privatpersoner på ämnet, C. Utökat återbruk, D. Återanvändning av lastpallar, E. Ökad sortering av schaktmassor ochF. Ändrad uppsamling av ris och gren. Dessa olika åtgärder agerar på olika nivåer i EUs avfallshierarki och kan implementeras tillsammans och var för sig. De olika åtgärderna har olika relevans nivåer som visar på ordningen de olika åtgärderna bör implementeras. Dock kan en ny relevans undersökning för varje specifik central vara gynnsam för en mer tillförlitlig bedömning. / In today's society we live with great climate challenges. One of the big problems is how we live and behave in our everyday lives. Our consumption patterns are not ecologically sustainable and as a result we are tearing on our planet. The long-term overexploitation has among other things meant that large amounts of waste have been formed. In addition to this, this type of exploitation also causes great strain on nature. Valuable natural areas are destroyed and result in a negative impact on biodiversity, which in the long run can affect ecosystem services such as our food production, nature's resistance to change and damage, important natural resources, recreational value in nature and all the other benefits we get from nature.  This study aims to investigate the potential development of Södertörn's Swedish Waste Management Agency's recycling centers related to the EU waste hierarchy in order to move towards increased circular resource management. The study shows the potential development at Södertörn's Renhållningsverk and how they can achieve this potential. The various solutions that are suggested are: A. A place for sharing economy, B. Inform private individuals on the subject, C. Increased recycling, D. Reuse of pallets, E. Increased sorting of excavated masses and F. Altered collection of rice and branches. These different solutions act on different levels in the EU's waste hierarchy and can be implemented together and separately. The different measures have different relevance levels that indicate the order in which the different measures should be implemented.  However, a new relevance study for each specific recyclingcenter may be favorable for a more reliable assessment.
109

Carbonation of concrete : Evaluation of CO2 uptake of Benders Sverige AB concrete products and landfills

Kessler, Juliana, Melander, Joakim, Tronde, Emil, Åderman, Gustav, Österlund, Erik January 2021 (has links)
The cement industry accounts for 5-7% of the global emissions of carbon dioxide, where CO2 is mainly emitted during the calcination process. However, CO2 is also absorbed by all concrete products during their lifetime through the process of carbonation. Based on a carbonation calculation model, this project investigated the CO2 uptake by Benders Sverige AB products and landfills.Benders Sverige AB produces mainly paving stones and roof tiles. During the years 2011-2020, more than 56,000 tonnes of CO2 were permanently absorbed by Benders’ products in use. This uptake corresponds to 9% of calcination emissions released during cement production. Roof tiles stand for &gt;77% of the CO2 uptake, which is most likely due to their high surface to volume ratio, which facilitates carbonation. Furthermore, roof tiles are surrounded by air whereas paving stones are mostly carbonated from their topside.It was also investigated how surface treatments affect the carbonation of roof tiles. A phenolphthalein test showed that surface treatments generally reduce carbonation, but since roof tiles are also carbonated from their underside it is possible that even surface treated roof tiles will be fully carbonated during their service life.To calculate the CO2 uptake of a concrete landfill, a hypothetical scenario was set up. The calculations show that there is a big potential in the optimisation of landfills to increase carbonation and therewith decrease the CO2 net emissions of Benders Sverige AB.
110

Water reuse in peri-urban areas : A case study of Kibondemaji, Dar es Salaam,Tanzania

Johansson, Niklas, Karlsson, Saga January 2019 (has links)
An increasing number of countries worldwide is becoming water-stressed, sub-Saharan Africa being one of the most recurrent regions within this discourse. Tanzania, one of the countries in the region, is no exception: large population growth has increased pressure on its precious water resources. The largest city, Dar es Salaam, has a poorly maintained and dimensioned water supply and wastewater system. However, as this system expands and more people are given access to the water network, the water consumption of the city is expected to increase. This is problematic for the whole city; however, peri-urban areas suffer the most from its consequences, e.g. periodical water shortages. This report seeks to investigate the potential for saving water in one of these peri-urban areas, Kibondemaji, by looking at fields of application and techniques for reuse of wastewater from showers. This is done via a literature review and interviews in the field in order to analyse and compare the different systems – reuse for tap water, irrigation and toilet flushing. The interviews showed that there is wide acceptance within the community for water reuse for toilet flushing but not for tap water or irrigation. Reuse for toilet flushing also requires less treatment than other fields of application, thus being the most promising technique for implementation in Kibondemaji.

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