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  • 1. Abbak, Ramazan A.
    et al.
    Sjöberg, Lars E.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geodesi och geoinformatik.
    Ellmann, Artu
    Ustun, Aydin
    A precise gravimetric geoid model in a mountainous area with scarce gravity data: a case study in central Turkey2012Ingår i: Studia Geophysica et Geodaetica, ISSN 0039-3169, E-ISSN 1573-1626, Vol. 56, nr 4, s. 909-927Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In mountainous regions with scarce gravity data, gravimetric geoid determination is a difficult task that needs special attention to obtain reliable results satisfying the demands, e.g., of engineering applications. The present study investigates a procedure for combining a suitable global geopotential model and available terrestrial data in order to obtain a precise regional geoid model for Konya Closed Basin (KCB). The KCB is located in the central part of Turkey, where a very limited amount of terrestrial gravity data is available. Various data sources, such as the Turkish digital elevation model with 3 '' x 3 '' resolution, a recently published satellite-only global geopotential model from the Gravity Recovery and Climate Experiment satellite (GRACE) and the ground gravity observations, are combined in the least-squares sense by the modified Stokes' formula. The new gravimetric geoid model is compared with Global Positioning System (GPS)/levelling at the control points, resulting in the Root Mean Square Error (RMS) differences of +/- 6.4 cm and 1.7 ppm in the absolute and relative senses, respectively. This regional geoid model appears to he more accurate than the Earth Gravitational Model 2008, which is the best global model over the target area, with the RMS differences of +/- 8.6 cm and 1.8 ppm in the absolute and relative senses, respectively. These results show that the accuracy of a regional gravimetric model can be augmented by the combination of a global geopotential model and local terrestrial data in mountainous areas even though the quality and resolution of the primary terrestrial data are not satisfactory to the geoid modelling procedure.

  • 2.
    Abbaszadeh Shahri, Abbas
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Spross, Johan
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Johansson, Fredrik
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Larsson, Stefan
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Landslide susceptibility hazard map in southwest Sweden using artificial neural network2019Ingår i: Catena (Cremlingen. Print), ISSN 0341-8162, E-ISSN 1872-6887, Vol. 183, artikel-id UNSP 104225Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Landslides as major geo-hazards in Sweden adversely impact on nearby environments and socio-economics. In this paper, a landslide susceptibility map using a proposed subdivision approach for a large area in southwest Sweden has been produced. The map has been generated by means of an artificial neural network (ANN) model developed using fourteen causative factors extracted from topographic and geomorphologic, geological, land use, hydrology and hydrogeology characteristics. The landslide inventory map includes 242 events identified from different validated resources and interpreted aerial photographs. The weights of the causative factors employed were analyzed and verified using accepted mathematical criteria, sensitivity analysis, previous studies, and actual landslides. The high accuracy achieved using the ANN model demonstrates a consistent criterion for future landslide susceptibility zonation. Comparisons with earlier susceptibility assessments in the area show the model to be a cost-effective and potentially vital tool for urban planners in developing cities and municipalities.

  • 3.
    Abdi, Amir
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Sawalha, Samer
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Karampour, Mazyar
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Heat recovery investigation of a supermarket refrigeration system using carbon dioxide as refrigerant2014Ingår i: 11th IIR Gustav Lorentzen Conference on Natural Refrigerants: Natural Refrigerants and Environmental Protection, GL 2014, International Institute of Refrigeration, 2014, s. 277-285Konferensbidrag (Refereegranskat)
    Abstract [en]

    This study investigates the heat reclaim of trans-critical CO2-booster refrigeration unit in a supermarket in Sweden. The aim is to compare the control strategy for heat recovery in real supermarket installation to the optimum control strategy.

    The optimum control strategy based on theoretical analysis is explained. By analyzing field measurement of a supermarket, heat recovery in the refrigeration system is studied and compared to the optimum case. To investigate the potential of higher heat recovery rate, a computer model is developed based on the optimum control strategy.  The model is also used to calculate the boundary conditions at which the system should run for highest COP.

    The results show that heat can be recovered at heating COP of 3-4.5. The theoretical analysis shows that the amount of heat that can be recovered from the refrigeration system is about 1.3 times (130 %) the cooling demand in the system. However the analysis of the field measurements shows that only between 30-60 % of the available heat to be recovered is utilized, the rest is released to outdoors. The analysis in this study shows that there is a potential to recover much more heat from the refrigeration system at relatively high heating COP compared to heat pump.

  • 4.
    Abdollahzadeh, Makan
    et al.
    K.N.Toosi University of Technology, Faculty of Geodesy and Geomatic Engineering, Tehran, Iran.
    Eshagh, Mehdi
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transporter och samhällsekonomi (stängd 20110301), Geodesi (stängd 20110301).
    Najafi, Mehdi
    K.N.Toosi University of Technology, Faculty of Geodesy and Geomatic Engineering, Tehran, Iran.
    A semi-vectorization algorithm to synthesis of gravitational anomaly quantities on the Earth's surface2009Konferensbidrag (Refereegranskat)
    Abstract [en]

    The Earth’s gravitational potential can be expressed by the well-known spherical harmonic expansion. The computationaltime of summing up this expansion is an important practical issue which can be reduced by an efficientnumerical algorithm. This paper proposes such a method for block-wise synthesizing the anomaly quantities onthe Earth surface using vectorization.Fully-vectorization means transformation of the summations to the simple matrix and vector products. It is not apractical for the matrices with large dimensions. Here a semi-vectorization algorithm is proposed to avoid workingwith large vectors and matrices. It speeds up the computations by using one loop for the summation either ondegrees or on orders. The former is a good option to synthesize the anomaly quantities on the Earth surfaceconsidering a digital elevation model (DEM). This approach is more efficient than the two-step method whichcomputes the quantities on the reference ellipsoid and continues them upward to the Earth surface. The algorithmhas been coded in MATLAB which synthesizes a global grid of 50 x 50 (corresponding 9 million points) of gravityanomaly or geoid height using a geopotential model to degree 360 in 10000 seconds by an ordinary computer with2G RAM.

  • 5.
    Abdollahzadeh, Makan
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik och Geodesi.
    Najafi-Alamdari, Mehdi
    Geodesy, KNToosi Uni. Tech..
    Application of Molodensky's Method for Precise Determination of Geoid in Iran2011Ingår i: Journal of Geodetic Science, ISSN 2081-9919, E-ISSN 2081-9943, Vol. 1, nr 3, s. 259-270Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Determination of the geoid with a high accuracy is a challenging task among geodesists. Its precise determination is usually carried out by combining a global geopotential model with terrestrial gravity anomalies measured in the region of interest along with some topographic information. In this paper, Molodensky's approach is used for precise determination of height anomaly. To do this, optimum combination of global geopotential models with the validated terrestrial surface gravity anomalies and some deterministic modification schemes are investigated. Special attention is paid on the strict modelling of the geoidal height and height anomaly difference. The accuracy of the determined geoid is tested on the 513 points of Iranian height network the geoidal height of which are determined by the GPS observations.

  • 6.
    Abdullah Asif, Farazee Mohammad
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion.
    Lieder, Michael
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion.
    Rashid, Amir
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion.
    Multi-method simulation based tool to evaluate economic and environmental performance of circular product systems2016Ingår i: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 139, s. 1261-1281Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Purpose: The transition from linear to circular product systems is a big step for any organization. This may require an organization to change the way it does business, designs product and manages supply chain. As these three areas are interdependent, bringing change in one area will influence the others, for instance, changing the business model from conventional sales to leasing will demand changes in both product design and the supply chain. At the same time, it is essential for an organization to anticipate the economic and environmental impact of all changes before it may decide to implement the circular product systems. However, there is no tool available today that can assess economic and environmental performance of circular product systems. The purpose of this research is to develop a multi-method simulation based tool that can help to evaluate economic and environmental performance of circular product systems. Method: The conceptual models that are used to develop the tool have been formulated based on review of the state-of-the-art research. System Dynamics (SD) and Agent Based (AB) principles have been used to create the simulation model which has been implemented in Anylogic software platform. Originality: This research presents the first multi-method simulation based tool that can evaluate economic and environmental performance of circular product systems. Findings: Multi-method simulation technique is useful in designing dynamic simulation model that takes into consideration mutual interactions among critical factors of business model, product design and supply chain. It also allows predicting system's behaviour and its influence on the economic and environmental performance of circular product systems.

  • 7.
    Abdullah Asif, Farazee Mohammad
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion.
    Rashid, Amir
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion, Maskin- och processteknologi.
    Bianchi, C.
    Nicolescu, Cornel Mihai
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion.
    System dynamics models for decision making in product multiple lifecycles2015Ingår i: Resources, Conservation and Recycling, ISSN 0921-3449, E-ISSN 1879-0658, Vol. 101, s. 20-33Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The main drivers for adopting product multiple lifecycles are to gain ecological and economic advantages. However, in most of the cases it is not straight forward to estimate the potential ecological and economic gain that may result from adopting product multiple lifecycles. Even though many researchers have concluded that product multiple lifecycles result in gain, there are examples which indicate that the gain is often marginal or even none in many cases. The purpose of this research is to develop system dynamics models that can assist decision makers in assessing and analysing the potential gain of product multiple lifecycles considering the dynamics of material scarcity. The foundation of the research presented in this paper is laid based on literature review. System dynamics principles have been used for modelling and simulations have been done on Stella iThink platform. The data used in the models have been extracted from different reports published by World Steel Association and U.S. Geological Survey. Some of the data have been assumed based on expert estimation. The data on iron ore reserves, iron and steel productions and consumptions have been used in the models. This research presents the first system dynamics model for decision making in product multiple lifecycles which takes into consideration the dynamics of material scarcity. Physical unavailability and price of material are the two main factors that would drive product multiple lifecycles approach and more sustainable decisions can be made if it is done by taking holistic system approach over longer time horizon. For an enterprise it is perhaps not attractive to conserve a particular type of material through product multiple lifecycles approach which is naturally abundant but extremely important if the material becomes critical. An enterprise could through engineering, proper business model and marketing may increase the share of multiple lifecycle products which eventually would help the enterprise to reduce its dependency on critical materials.

  • 8. Abiye, T. A.
    et al.
    Bhattacharya, Prosun
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik.
    Arsenic concentration in groundwater: Archetypal study from South Africa2019Ingår i: Groundwater for Sustainable Development, ISSN 2352-801X, Vol. 9, artikel-id 100246Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    South Africa does not have significant surface water resources, which is often easily affected by unpredictable and rapidly changing climatic variables, due to its location in the arid and semi-arid climatic setting. In large part of the country, groundwater from weathered and fractured crystalline rocks plays pivotal role in sustaining the livelihood, often it contains toxic metals released from the host rocks. The host rocks that are responsible for arsenic release in groundwater are primarily enriched due to metamorphism and igneous processes that resulted in the enrichment of economic minerals. Preliminary assessment indicates that the main arsenic containing minerals are arsenopyrite (FeAsS), arsenical oxide, sulpharsenide, arsenopyritical reefs, leucopyrite, löllingite (FeAs2) and scorodite (FeAsO4·2H2O). Owing to the release of arsenic from highly mineralized rocks that constitute the aquifers, arsenic concentration in the groundwater reaches up to 253 μg/L (Namaqualand), 6150 μg/L (west of Johannesburg), about 500 μg/L in the Karoo aquifers, considerably higher than the WHO guideline value of 10 μg/L. Acid mine drainage from coal and gold mining is also found to be an important source of arsenic and other toxic metals in groundwater.

  • 9. Abrehdary, M.
    et al.
    Sjoberg, Lars E.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Fastigheter och byggande, Geodesi och satellitpositionering.
    Sampietro, D.
    Contribution of satellite altimetry in modelling Moho density contrast in oceanic areas2019Ingår i: Journal of Applied Geodesy, ISSN 1862-9016, E-ISSN 1862-9024, Vol. 13, nr 1, s. 33-40Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The determination of the oceanic Moho (or crust-mantle) density contrast derived from seismic acquisitions suffers from severe lack of data in large parts of the oceans, where have not yet been sufficiently covered by such data. In order to overcome this limitation, gravitational field models obtained by means of satellite altimetry missions can be proficiently exploited, as they provide global uniform information with a sufficient accuracy and resolution for such a task. In this article, we estimate a new Moho density contrast model named MDC2018, using the marine gravity field from satellite altimetry in combination with a seismic-based crustal model and Earth's topographic/bathymetric data. The solution is based on the theory leading to Vening Meinesz-Moritz's isostatic model. The study results in a high-accuracy Moho density contrast model with a resolution of 1° × 1° in oceanic areas. The numerical investigations show that the estimated density contrast ranges from 14.2 to 599.7 kg/m 3 with a global average of 293 kg/m 3 . In order to evaluate the accuracy of the MDC2018 model, the result was compared with some published global models, revealing that our altimetric model is able to image rather reliable information in most of the oceanic areas. However, the differences between this model and the published results are most notable along the coastal and polar zones, which are most likely due to that the quality and coverage of the satellite altimetry data are worsened in these regions.

  • 10.
    Abrehdary, M.
    et al.
    Univ West HV, Div Math Comp & Surveying Engn, SE-46186 Trollhattan, Sweden..
    Sjöberg, L. E.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Fastigheter och byggande, Geodesi och satellitpositionering. Univ West HV, Div Math Comp & Surveying Engn, SE-46186 Trollhattan, Sweden..
    Recovering Moho constituents from satellite altimetry and gravimetric data for Europe and surroundings2019Ingår i: Journal of Applied Geodesy, ISSN 1862-9016, E-ISSN 1862-9024, Vol. 13, nr 4, s. 291-303Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this research, we present a local Moho model, named MOHV19, including Moho depth and Moho density contrast (or shortly Moho constituents) with corresponding uncertainties, which are mapped from altimetric and gravimetric data (DSNSC08) in addition to seismic tomographic (CRUST1.0) and Earth topographic data (Earth2014) to a resolution of 1 degrees x 1 degrees based on a solution of Vening Meinesz-Moritz' theory of isostasy. The MOHV19 model covers the area of entire European plate along with the surrounding oceans, bounded by latitudes (30 degrees N-82 degrees N) and longitudes (40 degrees W-70 degrees E). The article aims to interpret the Moho model resulted via altimetric and gravimetric information from the geological and geophysical perspectives along with investigating the relation between the Moho depth and Moho density contrast. Our numerical results show that estimated Moho depths range from 7.5 to 57.9 km with continental and oceanic averages of 41.3 +/- 4.9 km and 21.6 +/- 9.2 km, respectively, and an overall average of 30.9 +/- 12.3 km. The estimated Moho density contrast ranges from 60.2 to 565.8 kg/m(3), with averages of 421.8 +/- 57.9 and 284.4 +/- 62.9 kg/m(3) for continental and oceanic regions, respectively, with a total average of 350.3 +/- 91.5 kg/m(3). In most areas, estimated uncertainties in the Moho constituents are less than 3 km and 40 kg/m(3), respectively, but they reach to much more significant values under Iceland, parts of Gulf of Bothnia and along the Kvitoya Island. Comparing the Moho depths estimated by MOHV19 and those derived by CRUST1.0, MDN07, GRAD09 and MD19 models shows that MOHV19 agree fairly well with CRUST1.0 but rather poor with other models. The RMS difference between the Moho density contrasts estimated by MOHV19 and CRUST1.0 models is 49.45 kg/m(3).

  • 11.
    Abrehdary, Majid
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geodesi och satellitpositionering.
    Sjöberg, Lars E.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geodesi och satellitpositionering.
    Bagherbandi, Mohammad
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geodesi och satellitpositionering. Univ Gavle, Dept Ind Dev IT & Land Management, SE-80176 Gavle, Sweden.
    Combined Moho parameters determination using CRUST1.0 and Vening Meinesz-Moritz model2015Ingår i: Journal of Earth Science, ISSN 1674-487X, E-ISSN 1867-111X, Vol. 26, nr 4, s. 607-616Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    According to Vening Meinesz-Moritz (VMM) global inverse isostatic problem, either the Moho density contrast (crust-mantle density contrast) or the Moho geometry can be estimated by solving a non-linear Fredholm integral equation of the first kind. Here solutions to the two Moho parameters are presented by combining the global geopotential model (GOCO-03S), topography (DTM2006) and a seismic crust model, the latter being the recent digital global crustal model (CRUST1.0) with a resolution of 1A(0)x1A(0). The numerical results show that the estimated Moho density contrast varies from 21 to 637 kg/m(3), with a global average of 321 kg/m(3), and the estimated Moho depth varies from 6 to 86 km with a global average of 24 km. Comparing the Moho density contrasts estimated using our leastsquares method and those derived by the CRUST1.0, CRUST2.0, and PREM models shows that our estimate agrees fairly well with CRUST1.0 model and rather poor with other models. The estimated Moho depths by our least-squares method and the CRUST1.0 model agree to 4.8 km in RMS and with the GEMMA1.0 based model to 6.3 km.

  • 12.
    Abrehdary, Majid
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geodesi och satellitpositionering.
    Sjöberg, Lars E.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geodesi och satellitpositionering.
    Bagherbandi, Mohammad
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geodesi och satellitpositionering.
    The spherical terrain correction and its effect on the gravimetric-isostatic Moho determination2016Ingår i: Geophysical Journal International, ISSN 0956-540X, E-ISSN 1365-246X, Vol. 204, nr 1, s. 262-273Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this study, the Moho depth is estimated based on the refined spherical Bouguer gravity disturbance and DTM2006 topographic data using the Vening Meinesz-Moritz gravimetric-isostatic hypothesis. In this context, we compute the refined spherical Bouguer gravity disturbances in a set of 1 degrees x 1 degrees blocks. The spherical terrain correction, a residual correction to each Bouguer shell, is computed using rock heights and ice sheet thicknesses from the DTM2006 and Earth2014 models. The study illustrates that the defined simple Bouguer gravity disturbance corrected for the density variations of the oceans, ice sheets and sediment basins and also the non-isostatic effects needs a significant terrain correction to become the refined Bouguer gravity disturbance, and that the isostatic gravity disturbance is significantly better defined by the latter disturbance plus a compensation attraction. Our study shows that despite the fact that the lateral variation of the crustal depth is rather smooth, the terrain affects the result most significantly in many areas. The global numerical results show that the estimated Moho depths by the simple and refined spherical Bouguer gravity disturbances and the seismic CRUST1.0 model agree to 5.6 and 2.7 km in RMS, respectively. Also, the mean value differences are 1.7 and 0.2 km, respectively. Two regional numerical studies show that the RMS differences between the Moho depths estimated based on the simple and refined spherical Bouguer gravity disturbance and that using CRUST1.0 model yield fits of 4.9 and 3.2 km in South America and yield 3.2 and 3.4 km in Fennoscandia, respectively.

  • 13.
    Abshirini, Ehsan
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Koch, Daniel
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Arkitektur.
    Rivers as integration devices in cities2016Ingår i: City, Territory and Architecture, ISSN 0885-7024, E-ISSN 2195-2701, Vol. 3, nr 1, s. 1-21Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Background: As dynamic systems rivers and cities have been in interaction under changing relations over time, and the morphology of many cities has risen through a long and steady struggle between the city functions and the river system flowing inside. This makes river cities an interesting case to study how the presence of geographical features interacts with spatial morphology in the formation of cities.

    Methods: The basis of this research is enabled by utilizing a novel model for cross-city comparison presented by Hillier in his Santiago keynote in 2012 called a “star model”. This is done on large samples of cities investigating concurrent configurations, as well as how the properties in this star model react to specific forms of disturbance.

    Results: Results illustrate that the foreground network as identified through maximum choice values in cities are more vital to the structure of cities than the bridges. The overall syntactic structure tends to retain its character (degree of distributedness) and the location of its foreground network (which street segments constitute the foreground network) even when bridges are targeted. Furthermore, counter to the initial hypothesis, river cities tend to change less than non-river cities after targeted disturbance of the systems. Finally, the results show that while there is a statistical morphological difference between river cities and non-river cities, this difference is not directly explained through the bridges.

    Conclusion: Integrating space syntax with statistical and geospatial analysis can throw light on the way in which the properties of city networks and urban structure reflect the relative effect of rivers on the morphology of river cities. The paper, finally, contributes through offering one piece of a better perception of the structure of river-cities that can support strategies of river-cities interaction as well as enhance our knowledge on the constraints and limits to that interaction.

  • 14.
    Acuña, José
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Improvements of U-pipe Borehole Heat Exchangers2010Licentiatavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    The sales of Ground Source Heat Pumps in Sweden and many other countries are having a rapid growth in the last decade. Today, there are approximately 360 000 systems installed in Sweden, with a growing rate of about 30 000 installations per year. The most common way to exchange heat with the bedrock in ground source heat pump applications is circulating a secondary fluid through a Borehole Heat Exchanger (BHE), a closed loop in a vertical borehole. The fluid transports the heat from the ground to a certain heating and/or cooling application. A fluid with one degree higher or lower temperature coming out from the borehole may represent a 2-3% change in the COP of a heat pump system. It is therefore of great relevance to design cost effective and easy to install borehole heat exchangers. U-pipe BHEs consisting of two equal cylindrical pipes connected together at the borehole bottom have dominated the market for several years in spite of their relatively poor thermal performance and, still, there exist many uncertainties about how to optimize them. Although more efficient BHEs have been discussed for many years, the introduction of new designs has been practically lacking. However, the interest for innovation within this field is increasing nowadays and more effective methods for injecting or extracting heat into/from the ground (better BHEs) with smaller temperature differences between the heat secondary fluid and the surrounding bedrock must be suggested for introduction into the market.

    This report presents the analysis of several groundwater filled borehole heat exchangers, including standard and alternative U-pipe configurations (e.g. with spacers, grooves), as well as two coaxial designs. The study embraces measurements of borehole deviation, ground water flow, undisturbed ground temperature profile, secondary fluid and groundwater temperature variations in time, theoretical analyses with a FEM software, Distributed Thermal Response Test (DTRT), and pressure drop. Significant attention is devoted to distributed temperature measurements using optic fiber cables along the BHEs during heat extraction and heat injection from and to the ground.

  • 15.
    Adem Esmail, Blal
    et al.
    Department of Civil, Environmental, and Mechanical Engineering, University of Trento, Via Mesiano 77, Trento, 38123, Italy.
    Geneletti, Davide
    Department of Civil, Environmental, and Mechanical Engineering, University of Trento, Via Mesiano 77, 38123 Trento, Italy.
    Design and impact assessment of watershed investments: An approach based on ecosystem services and boundary work.2017Ingår i: Environmental impact assessment review, ISSN 0195-9255, E-ISSN 1873-6432, Vol. 62, s. 1-13Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Watershed investments, whose main aim is to secure water for cities, represent a promising opportunity for large-scale sustainability transitions in the near future. If properly designed, they promote activities in the watershed that enhance ecosystem services while protecting nature and biodiversity, as well as achieving other societal goals. In this paper, we build on the concepts of ecosystem services and boundary work, to develop and test an operative approach for designing and assessing the impact of watershed investments. The approach is structured to facilitate negotiations among stakeholders. Its strategic component includes setting the agenda; defining investment scenarios; and assessing the performance of watershed investments as well as planning for a follow-up. Its technical component concerns data processing; tailoring spatially explicit ecosystem service models; hence their application to design a set of “investment portfolios”, generate future land use scenarios, and model impacts on selected ecosystem services. A case study illustrates how the technical component can be developed in a data scarce context in sub-Saharan Africa in a way that is functional to support the steps of the strategic component. The case study addresses soil erosion and water scarcity-related challenges affecting Asmara, a medium-sized city in Eritrea, and considers urban water security and rural poverty alleviation as two illustrative objectives, within a ten-year planning horizon. The case study results consist in spatially explicit data (investment portfolio, land use scenario, impact on ecosystem services), which were aggregated to quantitatively assess the performance of different watershed investments scenarios, in terms of changes in soil erosion control. By addressing stakeholders' concerns of credibility, saliency, and legitimacy, the approach is expected to facilitate negotiation of objectives, definition of scenarios, and assessment of alternative watershed investments, ultimately, to contribute to implementing an adaptive watershed management.

  • 16. Adem Esmail, Blal
    et al.
    Geneletti, Davide
    Knowledge transfer and capacity building: an example from the urban water sector2018Ingår i: JUNCO Journal of UNiversities and international development COoperationnviron, Vol. 1, nr 1Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    Rural-to-urban migration and sustained natural population growth in Africa, if not properly addressed, may pose serious threat to ecosystems and human wellbeing, both locally and afar. Novel concepts and operative approaches are needed to better frame these challenges and support local decision-making processes, to promote sustainable development. Indeed, this is a key area in which the Academia can make a significant contribution, for example, exploring innovative concepts and developing related approaches to support decision-making processes at a local scale. This paper focuses on the urban water sector as an informative example, ultimately aiming to highlight key areas in which research can provide concrete and valuable assistance. More specifically, we introduce two innovative concepts, i.e. ecosystem services and boundary work; hence propose an operative approach to support the process of design and assessment of the impact of watershed investments. To illustrate real-life implementation of the approach in a data scarce context in sub-Saharan Africa, we consider as a case study soil erosion and water scarcity-related challenges affecting Asmara, a medium-sized city in Eritrea. Accordingly, we adopt urban water security and rural poverty alleviation as two illustrative objectives, within a ten-year planning horizon. The case study application resulted in spatially explicit outputs that inform decision-making processes. By timely addressing stakeholders' concerns of credibility, saliency, and legitimacy, the proposed approach is expected to facilitate negotiation of objectives, definition of scenarios, and assessment of alternative watershed investments. Above all, and beyond the urban water sector, the case study application helps highlighting key areas in which the academic work can make concrete contribution mainly in terms of knowledge transfer and capacity building.

  • 17.
    Adem Esmail, Blal
    et al.
    Univ Trento, Dept Civil Environm & Mech Engn, Trento, Italy..
    Geneletti, Davide
    Multi-criteria decision analysis for nature conservation: A review of 20 years of applications2018Ingår i: Methods in Ecology and Evolution, Vol. 9, s. 42-53Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    1. Multi-criteria decision analysis (MCDA) is a method to support decision-making, by exploring the balance between the pros and cons of different alternatives to ac- complish a specific goal. It assists in framing decision problems, illustrating the per- formance of alternatives across criteria, exploring trade-offs, formulating a decision and testing its robustness. This paper provides a structured review of empirical applications of MCDA to nature conservation published in the scientific literature over the last 20 years. The paper aims at taking stock of past experiences, and comparing them with best practices and common pitfalls identified in the literature, to provide recommendations for better MCDA application to conservation.

    2. The review follows the structure of a generalized MCDA process consisting of three key stages: (1) decision context and problem structuring, (2) analysis and (3) decision.

    3. The search identified 86 papers that describe MCDA applications to a range of top- ics, including conservation prioritization and planning; protected areas management and zoning; forest management and restoration; and mapping of biodiversity, naturalness and wilder. The results show that, concerning problem structuring, a small percentage of the reviewed MCDA engaged stakeholders other than the authors in identifying alternatives and formulating criteria (15% and 35% respectively). Concerning the analysis, criteria assessment was adequately justified by the authors (47%), at times also by involving other stakeholders (22%). Weighting was per- formed in almost all applications, whereas criteria aggregation was mostly based on the weighted linear combination (63%). Sensitivity analysis was largely overlooked (57%). Concerning decision, 45% of the articles provided only an overall ranking or suitability of alternatives, while 22% included additional rankings according to spe- cific criterion, and 8% further analyses and clustering of stakeholders’ preferences.

    4. The paper concludes by suggesting key elements of successful MCDA applications, including clear construction of the decision context; collaborative identification of alternatives and criteria that reflect the values at stake; adequate justification and communication of the methods for criteria assessment and weighting; reasoned choice of the criteria aggregation method, and comprehensive sensitivity analysis.

  • 18. Agarwal, S.
    et al.
    Wettlaufer, J. S.
    KTH, Centra, Nordic Institute for Theoretical Physics NORDITA. Yale University, New Haven, CT, USA; Mathematical Institute, University of Oxford, Oxford, UK.
    Fluctuations in Arctic sea-ice extent: Comparing observations and climate models2018Ingår i: Philosophical Transactions. Series A: Mathematical, physical, and engineering science, ISSN 1364-503X, E-ISSN 1471-2962, Vol. 376, nr 2129, artikel-id 20170332Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The fluctuation statistics of the observed sea-ice extent during the satellite era are compared with model output from CMIP5 models using a multifractal time series method. The two robust features of the observations are that on annual to biannual time scales the ice extent exhibits white noise structure, and there is a decadal scale trend associated with the decay of the ice cover. It is shown that (i) there is a large inter-model variability in the time scales extracted from the models, (ii) none of the models exhibits the decadal time scales found in the satellite observations, (iii) five of the 21 models examined exhibit the observed white noise structure, and (iv) the multi-model ensemble mean exhibits neither the observed white noise structure nor the observed decadal trend. It is proposed that the observed fluctuation statistics produced by this method serve as an appropriate test bed for modelling studies. 

  • 19. Agarwal, Sahil
    et al.
    Wettlaufer, John S.
    KTH, Centra, Nordic Institute for Theoretical Physics NORDITA. Yale University, United States; University of Oxford, United Kingdom.
    The Statistical Properties of Sea Ice Velocity Fields2017Ingår i: Journal of Climate, ISSN 0894-8755, E-ISSN 1520-0442, Vol. 30, nr 13, s. 4873-4881Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    By arguing that the surface pressure field over the Arctic Ocean can be treated as an isotropic, stationary, homogeneous, Gaussian random field, Thorndike estimated a number of covariance functions from two years of data (1979 and 1980). Given the active interest in changes of general circulation quantities and indices in the polar regions during the recent few decades, the spatial correlations in sea ice velocity fields are of particular interest. It is thus natural to ask, "How persistent are these correlations?'' To this end, a multifractal stochastic treatment is developed to analyze observed Arctic sea ice velocity fields from satellites and buoys for the period 1978-2015. Since it was previously found that the Arctic equivalent ice extent (EIE) has a white noise structure on annual to biannual time scales, the connection between EIE and ice motion is assessed. The long-term stationarity of the spatial correlation structure of the velocity fields and the robustness of their white noise structure on multiple time scales is demonstrated; these factors (i) combine to explain the white noise characteristics of the EIE on annual to biannual time scales and (ii) explain why the fluctuations in the ice velocity are proportional to fluctuations in the geostrophic winds on time scales of days to months. Moreover, it is shown that the statistical structure of these two quantities is commensurate from days to years, which may be related to the increasing prevalence of free drift in the ice pack.

  • 20.
    Ahlberg, Jesper
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Biogeofysik.
    Gustafsson, David
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Biogeofysik.
    Distributed snow modelling integrating ground penetrating radar data for improved runoff predictions in a Swedish mountain basin2009Ingår i: EGU General Assembly 2009, 2009Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Operational forecasts of snow melt runoff in Sweden are currently running with precipitation and temperature as the main input variables and calibrated with runoff data, and there is an interest to make better use of new measurement systems for distributed snow data. At the same time, various data assimilation techniques are becoming more frequently used in hydrological modeling, in order to reduce uncertainties related to both model structure errors and errors in input and calibration data. Thus, it is important to address not only what type of snow data that can be used to improve the model predictions, but also what type of input data and model structures that are optimal in relation to the available snow data. The objective of this study is to investigate to what extent the runoff predictions can be improved by assimilation of temporal and spatially distributed snow data, and if the improvements depend on the choice of model structures, for instance the use of energy balance or day-degree snow models. In order to achieve these objectives a new distributed snow model has been implemented into the hydrological modeling framework HYSS/HYPE. This model can easily be setup with either an energy balance model or a day-degree model for the snow pack calculations, and it is easy to run the model with different spatial resolutions. In the fully distributed case, snow drift processes are implicitly included in the model through a precipitation distribution model, based on topographical information and wind direction. The model was applied to a mountain basin in northern Sweden used for hydropower production, where extensive snow measurements were taken during the last two winters 2007-2009. A climate station is located at the outlet of the regulation lake, including automated point measurements of snow depth, snow mass (snow pillow), snow wetness and snow temperature. Distributed snow cover data was sampled using ground-penetrating radar from snow mobiles. Measurements were taken at the time of the maximum snow cover, providing a data set with snow depth, snow density, snow water equivalent along 20 km long transects in representative areas of the basin. The precipitation distribution model was calibrated using the distributed SWE data from the GPR measurements. Application of the calibrated model to previous years without available snow data show that the runoff predictions was improved compared to calibrations without the distributed snow data, however the improvements were larger for the energy balance compared to the day-degree model. Further developments will include assimilation of the temporal and spatial snow data to adjust the distribution of various input variables, for instance air temperature and wind speed.

  • 21.
    Ahlberg, Jesper
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Biogeofysik.
    Gustafsson, David
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Biogeofysik.
    Snow melt runoff simulations using ensemble Kalman filter assimilation of distributed snow data2010Konferensbidrag (Övrigt vetenskapligt)
  • 22.
    Ahlgren, Serina
    et al.
    SLU.
    Björklund, Anna
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Miljöstrategisk analys (fms).
    Ekman, Anna
    Lund University.
    Karlsson, H
    SLU.
    Berlin, Johanna
    SP.
    Börjesson, Pål
    Lund University.
    Ekvall, Tomas
    IVL.
    Finnveden, Göran
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Miljöstrategisk analys (fms).
    Janssen, Matty
    Chalmers.
    Strid, Ingrid
    SLU.
    LCA of biorefinieries -identification of key issues and methodological recommendations2013Rapport (Övrigt vetenskapligt)
  • 23.
    Ahlgren, Serina
    et al.
    Swedish University of Agricultural Sciences.
    Björklund, Anna
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Miljöstrategisk analys (fms).
    Ekman, Anna
    SP Technical Research Institute of Sweden.
    Karlsson, Hanna
    Swedish University of Agricultural Sciences.
    Berlin, Johanna
    SP Technical Research Institute of Sweden.
    Börjesson, Pål
    Lund University.
    Ekvall, Tomas
    IVL Swedish Environmental Research Institute.
    Finnveden, Göran
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Miljöstrategisk analys (fms).
    Janssen, Matty
    Chalmers University of Technology.
    Strid, Ingrid
    Swedish University of Agricultural Sciences.
    Review of methodological choices in LCA of biorefinery systems: key issues and recommendations2015Ingår i: Biofuels, Bioproducts and Biorefining, ISSN 1932-104X, E-ISSN 1932-1031, Vol. 9, nr 5, s. 606-619Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The current trend in biomass conversion technologies is toward more efficient utilization of biomass feedstock in multiproduct biorefineries. Many life-cycle assessment (LCA) studies of biorefinery systems have been performed but differ in how they use the LCA methodology. Based on a review of existing LCA standards and guidelines, this paper provides recommendations on how to handle key methodological issues when performing LCA studies of biorefinery systems. Six key issues were identified: (i) goal definition, (ii) functional unit, (iii) allocation of biorefinery outputs, (iv) allocation of biomass feedstock, (v) land use, and (vi) biogenic carbon and timing of emissions. Many of the standards and guidelines reviewed here provide only general methodological recommendations. Some make more specific methodological recommendations, but these often differ between standards. In this paper we present some clarifications (e.g. examples of research questions and suitable functional units) and methodological recommendations (e.g. on allocation).

  • 24.
    Ahlmer, Anna-Klara
    et al.
    KTH. Trivector Traff, Stockholm, Sweden.
    Cavalli, Marco
    CNR, Res Inst Geohydrol Protect, Padua, Italy..
    Hansson, Klas
    Swedish Transport Adm Trafikverket, S-17290 Stockholm, Sweden..
    Koutsouris, Alexander J.
    Stockholm Univ, Dept Phys Geog, S-10691 Stockholm, Sweden..
    Crema, Stefano
    CNR, Res Inst Geohydrol Protect, Padua, Italy..
    Kalantari, Zahra
    Stockholm Univ, Dept Phys Geog, S-10691 Stockholm, Sweden.;Stockholm Univ, Bolin Ctr Climate Res, S-10691 Stockholm, Sweden..
    Soil moisture remote-sensing applications for identification of flood-prone areas along transport infrastructure2018Ingår i: Environmental Earth Sciences, ISSN 1866-6280, E-ISSN 1866-6299, Vol. 77, nr 14, artikel-id 533Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The expected increase in precipitation and temperature in Scandinavia, and especially short-time heavy precipitation, will increase the frequency of flooding. Urban areas are the most vulnerable, and specifically, the road infrastructure. The accumulation of large volumes of water and sediments on road-stream intersections gets severe consequences for the road drainage structures. This study integrates the spatial and temporal soil moisture properties into the research about flood prediction methods by a case study of two areas in Sweden, Vastra Gotaland and Varmland, which was affected by severe flooding in August 2014. Soil moisture data are derived from remote-sensing techniques, with a focus on the soil moisture-specific satellites ASCAT and SMOS. Furthermore, several physical catchments descriptors (PCDs) are analyzed and the result shows that larger slopes and drainage density, in general, mean a higher risk of flooding. The precipitation is the same; however, it can be concluded that more precipitation in most cases gives higher soil moisture values. The lack, or the dimensioning, of road drainage structures seems to have a large impact on the flood risk as more sediment and water can be accumulated at the road-stream intersection. The results show that the method implementing soil moisture satellite data is promising for improving the reliability of flooding.

  • 25.
    Ahmad, Arslan
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik.
    Bhattacharya, Prosun
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Vatten- och miljöteknik.
    Arsenic in Drinking Water: Is 10 μg/L a Safe Limit?2019Ingår i: Current Pollution Reports, ISSN 2198-6592, Vol. 5, nr 1Artikel i tidskrift (Refereegranskat)
  • 26.
    Ahmad, Arslan
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Hållbarhet och miljöteknik. KWR Water Cycle Res Inst, Nieuwegein, Netherlands.;WUR, Dept Environm Technol, Wageningen, Netherlands..
    Cornelissen, Emile
    KWR Water Cycle Res Inst, Nieuwegein, Netherlands.;Nanyang Technol Univ, Nanyang Environm & Water Res Inst, Singapore Membrane Technol Ctr, Singapore, Singapore.;Univ Ghent, Particle & Interfacial Technol Grp, Ghent, Belgium..
    van de Wetering, Stephan
    Brabant Water NV Breda, Breda, Netherlands..
    van Dijk, Tim
    Brabant Water NV Breda, Breda, Netherlands..
    van Genuchten, Case
    Univ Utrecht, Fac Geosci, Dept Earth Sci Geochem, Utrecht, Netherlands..
    Bundschuh, Jochen
    Univ Southern Queensland, Int Ctr Appl Climate Sci, West St, Toowoomba, Qld, Australia.;Univ Southern Queensland, Deputy Vice Chancellors Off Res & Innovat, Toowoomba, Qld, Australia.;Univ Southern Queensland, Fac Hlth Engn & Sci, Toowoomba, Qld, Australia..
    van der Wal, Albert
    WUR, Dept Environm Technol, Wageningen, Netherlands.;Evides Water Co NV Rotterdam, Rotterdam, Netherlands..
    Bhattacharya, Prosun
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik. Univ Southern Queensland, Int Ctr Appl Climate Sci, West St, Toowoomba, Qld, Australia..
    Arsenite removal in groundwater treatment plants by sequential Permanganate-Ferric treatment2018Ingår i: JOURNAL OF WATER PROCESS ENGINEERING, ISSN 2214-7144, Vol. 26, s. 221-229Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Dutch drinking water sector is actively investigating methods to reduce arsenic (As) to < 1 mu g/L in drinking water supply. We investigated (1) the effectiveness of sequential permanganate (MnO4-)-ferric (Fe(III)) dosing during aeration-rapid sand filtration to achieve < 1 mu g/L As (2) the influence of MnO4--Fe(III) dosing on preestablished removal patterns of As(III), Fe(II), Mn(II) and NH4+ in rapid sand filters and (3) the influence of MnO4--Fe(III) dosing on the settling and molecular-scale structural properties of the filter backwash solids. We report that MnO4--Fe(III) dosing is an effective technique to improve arsenite [As(III)] removal at groundwater treatment plants. At a typical aeration-rapid sand filtration facility in the Netherlands effluent As concentrations of < 1 mu g/L were achieved with 1.2 mg/L MnO4--and 1.8 mg/L Fe(III). The optimized combination of MnO4-and Fe(III) doses did not affect the removal efficiency of Fe(II), Mn(II) and NH4+ in rapid sand filters, however, the removal patterns of Fe(II) and Mn(II) in rapid sand filter were altered, as well as the settling behaviour of backwash solids. The characterization of backwash solids by Fe K-edge X-ray absorption spectroscopy (XAS) and X-ray diffraction (XRD) showed that the changed settling velocity of backwash solids with MnO4-Fe(III) in place was not due to changes in the molecular-scale structure of Fe-precipitates that constitute the major portion of the backwash solids.

  • 27.
    Ahmad, Arslan
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik. Hoofd Ingenieursbureau, Brabant Water N.V., 's-Hertogenbosch, Netherlands .
    Van De Wetering, S.
    Groenendijk, M.
    Bhattacharya, Prosun
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik.
    Advanced Oxidation-Coagulation-Filtration (AOCF) - An innovative treatment technology for targeting drinking water with <1 μg/L of arsenic2014Ingår i: One Century of the Discovery of Arsenicosis in Latin America (1914-2014): As 2014 - Proceedings of the 5th International Congress on Arsenic in the Environment, CRC Press, 2014, s. 817-819Konferensbidrag (Refereegranskat)
    Abstract [en]

    Advanced Oxidation-Coagulation-Filtration (AOCF) has been investigated for producing drinking water with less than 1 μg L-1 of As through a series of bench scale and pilot scale experiments. At bench scale, the suitable coagulant, its combination dose with KMnO4 oxidant, the optimum process pH and kinetics of As removal were determined. The optimized AOCF technique was capable of consistently reducing the As concentration to below 1 μg L-1 when implemented at pilot scale and did not adversely affect the already existing removal processes of Fe, Mn and NH4 +. Dual media filter solved the filter run time reduction issue.

  • 28.
    Ahmad, Arslan
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik. KWR Water Cycle Res Inst, Nieuwegein, Netherlands.;WUR, Dept Environm Technol, Wageningen, Netherlands.;Evides Water Co NV, Rotterdam, Netherlands..
    van der Wal, Albert
    WUR, Dept Environm Technol, Wageningen, Netherlands.;Evides Water Co NV, Rotterdam, Netherlands..
    Bhattacharya, Prosun
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik. Univ Southern Queensland, Int Ctr Appl Climate Sci, Toowoomba, Qld, Australia..
    van Genuchten, Case M.
    Geol Survey Denmark & Greenland GEUS, Geochem Dept, Copenhagen, Denmark.;Univ Utrecht, Fac Geosci, Dept Earth Sci Geochem, Utrecht, Netherlands..
    Characteristics of Fe and Mn bearing precipitates generated by Fe(II) and Mn(II) co-oxidation with O-2, MnO4 and HOCl in the presence of groundwater ions2019Ingår i: Water Research, ISSN 0043-1354, E-ISSN 1879-2448, Vol. 161, s. 505-516Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this work, we combined macroscopic measurements of precipitate aggregation and chemical composition (Mn/Fe solids ratio) with Fe and Mn K-edge X-ray absorption spectroscopy to investigate the solids formed by co-oxidation of Fe(II) and Mn(II) with O-2, MnO4, and HOCl in the presence of groundwater ions. In the absence of the strongly sorbing oxyanions, phosphate (P) and silicate (Si), and calcium (Ca), O-2 and HOCl produced suspensions that aggregated rapidly, whereas co-oxidation of Fe(II) and Mn(II) by MnO4 generated colloidally stable suspensions. The aggregation of all suspensions decreased in P and Si solutions, but Ca counteracted these oxyanion effects. The speciation of oxidized Fe and Mn in the absence of P and Si also depended on the oxidant, with O-2 producing Mn(III)-incorporated lepidocrocite (Mn/Fe = 0.01-0.02 mol/mol), HOCl producing Mn(III)-incorporated hydrous ferric oxide (HFO) (Mn/Fe = 0.08 mol/mol), and MnO4 producing poorly-ordered MnO2 and HFO (Mn/Fe > 0.5 mol/mol). In general, the presence of P and Si decreased the crystallinity of the Fe(III) phase and increased the Mn/Fe solids ratio, which was found by Mn K-edge XAS analysis to be due to an increase in surface-bound Mn(II). By contrast, Ca decreased the Mn/Fe solids ratio and decreased the fraction of Mn(II) associated with the solids, suggesting that Ca and Mn(II) compete for sorption sites. Based on these results, we discuss strategies to optimize the design (i.e. filter bed operation and chemical dosing) of water treatment plants that aim to remove Fe(II) and Mn(II) by co-oxidation.

  • 29.
    Ahmad, Arslan
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik. Department of Environmental Technology, Wageningen University and Research (WUR), Wageningen, Netherlands.
    van der Wens, Patrick
    Brabant Water NV Breda, Breda, Netherlands..
    Baken, Kirsten
    KWR Water Cycle Res Inst, Groningenhaven 7, NL-3433 PE Nieuwegein, Netherlands..
    de Waal, Luuk
    KWR Water Cycle Res Inst, Groningenhaven 7, NL-3433 PE Nieuwegein, Netherlands..
    Bhattacharya, Prosun
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik.
    Stuyfzand, Pieter
    KWR Water Cycle Res Inst, Groningenhaven 7, NL-3433 PE Nieuwegein, Netherlands.;Delft Univ Technol, Dept Geosci & Engn, Delft, Netherlands..
    Arsenic reduction to < 1 mu g/L in Dutch drinking water2020Ingår i: Environment International, ISSN 0160-4120, E-ISSN 1873-6750, Vol. 134, artikel-id 105253Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Arsenic (As) is a highly toxic element which naturally occurs in drinking water. In spite of substantial evidence on the association between many illnesses and chronic consumption of As, there is still a considerable uncertainty about the health risks due to low As concentrations in drinking water. In the Netherlands, drinking water companies aim to supply water with As concentration of < 1 mu g/L - a water quality goal which is tenfold more stringent than the current WHO guideline. This paper provides (i) an account on the assessed lung cancer risk for the Dutch population due to pertinent low-level As in drinking water and cost-comparison between health care provision and As removal from water, (ii) an overview of As occurrence and mobility in drinking water sources and water treatment systems in the Netherlands and (iii) insights into As removal methods that have been employed or under investigation to achieve As reduction to < 1 mu g/L at Dutch water treatment plants. Lowering of the average As concentration to < 1 mu g/L in the Netherlands is shown to result in an annual benefit of 7.2-14 M(sic). This study has a global significance for setting drinking water As limits and provision of safe drinking water.

  • 30.
    Ahmad, Nawaz
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Vattendragsteknik. Policy Wing, Ministry of Petroleum and Natural Resources, Government of Pakistan, Pakistan.
    Wörman, Anders
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Vattendragsteknik.
    Bottacin-Busolin, Andrea
    Sanchez-Vila, Xavier
    Reactive transport modeling of leaking CO2-saturated brine along a fractured pathway2015Ingår i: International Journal of Greenhouse Gas Control, ISSN 1750-5836, E-ISSN 1878-0148, Vol. 42, s. 672-689Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    One concern regarding the underground storage of carbon dioxide (CO2) is its potential leakage from reservoirs. Over short period of time, the leakage risk is related mainly to CO2 as a separate supercritical fluid phase. However, over longer periods upon complete dissolution of injected CO2 in the fluid, the leakage risk is associated with dissolved phase CO2. Over the geological time scales, large-scale groundwater motion may cause displacement of brine containing dissolved CO2 along the conducting pathways. In this paper, we present a comprehensive modeling framework that describes the reactive transport of CO2-saturated brine along a fracture in the clay caprock based on the future, hypothetical leakage of the dissolved phase CO2. This study shows that the transport of leaked dissolved CO2 is significantly retarded by a combination of various physical and geochemical processes, such as mass exchange between conducting fracture and the neighboring rock matrix through molecular diffusion, sorption and calcite dissolution in the rock matrix. Mass stored in aqueous and adsorbed states in the rock matrix caused retention of dissolved CO2 along the leakage pathway. Calcite dissolution reaction in the rock matrix resulted in consumption of leaking dissolved CO2 and reduced its mass along the leakage pathway. Consumption and retention of dissolved CO2 along the leakage pathway have important implications for analyzing the potential reduction of CO2 fluxes from storage reservoirs over large periods and long travel pathways.

  • 31.
    Ahmad, Nawaz
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Vattendragsteknik. Ministry of Petroleum and Natural Resources, Pakistan.
    Wörman, Anders
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Vattendragsteknik.
    Sanchez-Vila, X.
    Jarsjö, J.
    Bottacin-Busolin, A.
    Hellevang, H.
    Injection of CO2-saturated brine in geological reservoir: A way to enhanced storage safety2016Ingår i: International Journal of Greenhouse Gas Control, ISSN 1750-5836, E-ISSN 1878-0148, Vol. 54, s. 129-144Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Injection of free-phase supercritical CO2 into deep geological reservoirs is associated with risk of considerable return flows towards the land surface due to the buoyancy of CO2, which is lighter than the resident brine in the reservoir. Such upward movements can be avoided if CO2 is injected in the dissolved phase (CO2aq). In this work, injection of CO2-saturated brine in a subsurface carbonate reservoir was modelled. Physical and geochemical interactions of injected low-pH CO2-saturated brine with the carbonate minerals (calcite, dolomite and siderite) were investigated in the reactive transport modelling. CO2-saturated brine, being low in pH, showed high reactivity with the reservoir minerals, resulting in a significant mineral dissolution and CO2 conversion in reactions. Over the injection period of 10 yr, up to 16% of the injected CO2 was found consumed in geochemical reactions. Sorption included in the transport analysis resulted in additional quantities of CO2 mass stored. However, for the considered carbonate minerals, the consumption of injected CO2aq was found mainly in the form of ionic trapping.

  • 32. Ahmed, K. M.
    et al.
    Bhattacharya, Prosun
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik.
    Groundwater arsenic mitigation in Bangladesh: Two decades of advancements in scientific research and policy instruments2014Ingår i: One Century of the Discovery of Arsenicosis in Latin America (1914-2014): As 2014 - Proceedings of the 5th International Congress on Arsenic in the Environment, 2014, s. 886-888Konferensbidrag (Refereegranskat)
    Abstract [en]

    Two decades have passed since the first detection of arsenic above allowable limits in groundwater of Bangladesh. A good number of scientific research and mitigation projects have so far been completed but still today more than 22 million people are exposed to arsenic leaves of 50 μg L-1 or more. As there are many untested new wells, it is not precisely known how many people are exposed to what level. Scientific knowledge about occurrences, distribution and release mechanisms have enhanced significantly. Although deep tube wells have emerged as the most effective mitigation measure over most of the country, still there are areas where this does not work. Recent studies reported effectiveness of alternative options like intermediate deep wells and subsurface arsenic removal. There has been a major paradigm shift in the policy arena regarding arsenic mitigation.

  • 33. Ahmed, K. M.
    et al.
    Sultana, S.
    Hasan, M. A.
    Bhattacharya, Prosun
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik (flyttat 20130630), Miljögeokemi och ekoteknik.
    Hasan, M. K.
    Burgess, W. K.
    Hoque, M. A.
    Groundwater quality contrasts between Upper and Lower Dupi Tila Aquifers in Megacity Dhaka, Bangladesh2011Ingår i: Groundwater quality contrasts between Upper and Lower Dupi Tila Aquifers in Megacity Dhaka, Bangladesh: Proc. 7th International Groundwater Quality Conference, 2011, s. 71-74Konferensbidrag (Refereegranskat)
    Abstract [en]

    Dhaka is one of the fastest growing megacities of the world and is set to become the third largest by 2025. Currently about 86% of the municipal water supply comes from over 500 wells drilled in the Dupi Tila aquifers underlying the city. The Upper Dupi Tila aquifer (UDTA) is overexploited and a large part has been dewatered; abstractions from the lower Dupi Tila started only recently. Results of water analysis and EC surveys have been used to decipher the variations in groundwater quality in the UDTA and LDTA. EC surveys reveal a systematic deterioration of water quality in the vicinity of the Buriganga River in southeast Dhaka. The UDTA is more widely affected by anthropogenic processes than the LDTA, which still largely exhibits its intrinsic water quality characteristics. Regular monitoring and proper management practices are essential to protect the quality of this precarious resource.

  • 34. Aigelsperger, Lisa
    et al.
    Kummer, Susanne
    Milestad, Rebecka
    Department of Urban and Rural Studies, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Vogl, Christian R.
    Chowdhury, A.
    Knowledge systems, innovations and social learning in organic farming: An Overwiev2010Ingår i: Proceedings of the 9th European IFSA Symposium, 2010, s. 664-669Konferensbidrag (Refereegranskat)
  • 35. Aikio, A. T.
    et al.
    Mursula, K.
    Buchert, S.
    Forme, F.
    Amm, O.
    Marklund, Göran T.
    KTH, Tidigare Institutioner, Alfvénlaboratoriet.
    Dunlop, M.
    Fontaine, D.
    Vaivads, A.
    Fazakerley, A.
    Temporal evolution of two auroral arcs as measured by the Cluster satellite and coordinated ground-based instruments2004Ingår i: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 22, nr 12, s. 4089-4101Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The four Cluster s/c passed over Northern Scandinavia on 6 February 2001 from south-east to north-west at a radial distance of about 4.4 R-E in the post-midnight sector. When mapped along geomagnetic field lines, the separation of the spacecraft in the ionosphere was confined to within 110 km in latitude and 50 km in longitude. This constellation allowed us to study the temporal evolution of plasma with a time scale of a few minutes. Ground-based instrumentation used involved two all-sky cameras, magnetometers and the EISCAT radar. The main findings were as follows. Two auroral arcs were located close to the equatorward and poleward edge of a large-scale density cavity, respectively. These arcs showed a different kind of a temporal evolution. (1) As a response to a pseudo-breakup onset, both the up- and downward field-aligned current (FAC) sheets associated with the equatorward arc widened and the total amount of FAC doubled in a time scale of 1-2 min. (2) In the poleward arc, a density cavity formed in the ionosphere in the return (downward) current region. As a result of ionospheric feedback, a strongly enhanced ionospheric southward electric field developed in the region of decreased Pedersen conductance. Furthermore, the acceleration potential of ionospheric electrons, carrying the return current, increased from 200 to 1000 eV in 70 s, and the return current region widened in order to supply a constant amount of return current to the arc current circuit. Evidence of local acceleration of the electron population by dispersive Alfven waves was obtained in the upward FAC region of the poleward arc. However, the downward accelerated suprathermal electrons must be further energised below Cluster in order to be able to produce the observed visible aurora. Both of the auroral arcs were associated with broad-band ULF/ELF (BBELF) waves, but they were highly localised in space and time. The most intense BBELF waves were confined typically to the return current regions adjacent to the visual arc, but in one case also to a weak upward FAC region. BBELF waves could appear/disappear between s/c crossings of the same arc separated by about 1 min.

  • 36.
    Alam, M.S.
    et al.
    Memorial University of Newfoundland, Canada.
    Ahmed, Kazi Matin
    University of Dhaka, Bangladesh.
    Hasan, M.A.
    University of Dhaka, Bangladesh.
    Hossain, Muhammed
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik (flyttat 20130630), Miljögeokemi och ekoteknik.
    Bhattacharya, Prosun
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik (flyttat 20130630), Miljögeokemi och ekoteknik.
    Controls of sedimentary facies on arsenic mobilization in shallow aquifers of the Matlab North Upazila, southeastern Bangladesh2013Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Groundwater extracted from shallow (<100 m bgl) Holocene alluvial aquifers, is the primary source of drinking water in Matlab North Upazila, Southeast Bangladesh. The distribution of lithofacies and its relation to hydrochemistry in such heterogeneous deposits are of fundamental importance for the analysis of groundwater quality. Aquifer sediment samples were collected from 48 locations throughout the study area. Lithofacies distribution was characterized using grain size and sediment colors. Channel fills (sandy) and over bank (silt-clay) deposits the two main lithofacies groups, were identified. These sandy deposits represent an active meandering river or channel fills sediment sequence, which are usually capped by silts and clays of an over bank sediment sequence. All the collected sediments samples were generalized and subdivided based on four distinct color variations, such as Black, White, Off-white, and Red according to Munsell color chart and water-well drillers’ perception.

    Mineral compositions showed variability with the sediment color and grain size. Red and off-white sediments contain fewer amounts of metastable minerals (hornblende, actinolite, kyanite and pyroxenes etc.) than that of black sediments, whereas black sediments contain higher amount of biotite. The relatively high content of biotite and other dark colored ferromagnesian minerals are responsible for the black and grayish color of these sediments. Ferruginous coating on silicates, particularly on quartz grains, gives the red and off-white coloration. Based on the available information regarding sediment colors of aquifers in which tubewell screens were placed, 44 domestic hand pumped tubewells (HTWs) were selected for water sampling. The groundwater abstracted from black sediments of shallow aquifer showed higher concentrations in DOC (median: 5.81 mg/L), dissolved NH

    4+ (median: 3.47 mg/L), PO43- (median: 1.36 mg/L), Fe (median: 4.87 mg/L), As (median: 252.53 μg/L) and relatively low Mn (median: 0.54 mg/L) and SO42-(median: 0.59 mg/L) concentrations, whereas groundwater abstracted from off-white and red sediments of shallow aquifer showed lower concentrations in DOC (median: 1.95 and 1.71 mg/L, respectively), dissolved NH4+ (median: 0), PO43- (median: 0.14 and 0.04 mg/L, respectively), Fe (median: 2.25 and 0.63 mg/L, respectively), As (median: 17.36 and 15.05 μg/L, respectively) and relatively high Mn+2 (median: 1.12 and 1.15 mg/L, respectively) and SO42- (median: 0.79 and 0.78 mg/L, respectively) concentrations. The water samples collected from black sediments (median Eh: 211 mV) indicated most reducing environment, followed by white (median Eh: 227 mV), whereas off-white and red sediments (median Eh: 268 and 274 mV) signified less reducing environment. The study supports that the sediment colors in shallow aquifer can be a reliable indicator of high and low-As concentrations and can be a useful tool for local drillers to target arsenic safe aquifers.

  • 37.
    Albrecht, Martin
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Miljöstrategisk analys (fms).
    Nordic power road map 2050: Strategic choices towards carbon neutrality. D4.1.R Institutional grid review.2013Rapport (Övrigt vetenskapligt)
  • 38.
    Albrecht, Martin
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Miljöstrategisk analys (fms).
    Nilsson, Måns
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Miljöstrategisk analys (fms). Stockholm University, Stockholm Environment Institute.
    Åkerman, Jonas
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Miljöstrategisk analys (fms).
    Electrification of vehicles – policy drivers and impacts in two scenarios.2013Ingår i: Grid Integration of Electric Vehicles in Open Electricity Markets / [ed] Qiuwei Wu, John Wiley & Sons, 2013Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    This chapter examines current policy drivers of battery electric vehicles (EVs) and plug-in hybrid EVs, the current and anticipated impacts on carbon emissions, as well as what potential role policy can play in enhancing the innovation system and market development around such vehicles in the future. We start with a policy review of key targets in the Nordic countries and the EU, up to 2030, and discuss to what extent they are consistent with industry and expert estimates of how the systems can grow. On the basis of this, the second part elaborates two simple scenarios of EV development in the EU: one breakthrough expansion scenario and one incremental expansion scenario. Building on that is an analysis of the climate impacts of the two scenarios, given different assumptions relating to, for example, electricity production as well as EV penetration in the fleet. The third part examines what policy drivers might be needed to enable the breakthrough scenario, using a technological innovation systems perspective to describe the needed processes, drivers and developments.

  • 39.
    Albrecht, Martin
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Miljöstrategisk analys (fms).
    Nilsson, Måns
    Åkerman, Jonas
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Miljöstrategisk analys (fms).
    Nordic power road map 2050:Strategic choices towards carbon neutrality. D4.2.R Policy and Institutional Review Electric Vehicles (EV).2012Rapport (Övrigt vetenskapligt)
    Abstract [en]

    This report examines policy drivers of electric vehicles (EVs), and what potential role policy can play in enhancing the innovation and market development of EVs. We start with a policy review of key targets in the Nordic countries and the EU, up to 2030, and discuss to what extent they are consistent with industry, government and expert estimates of how the EV innovation systems can grow. On the basis of this, the second part examines what policy drivers might be needed to enable a breakthrough scenario, using a technological innovation systems (TIS) perspective to describe the needed processes, drivers and developments in policy and technology.

  • 40.
    Alemrajabi, Mahmood
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Forsberg, Kerstin
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Korkmaz, Kivanc
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Rasmuson, Åke C.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Isolation of rare earth element phosphate precipitate in the nitrophosphate process for manufacturing of fertilizer2016Ingår i: IMPC 2016 - 28th International Mineral Processing Congress, Canadian Institute of Mining, Metallurgy and Petroleum , 2016Konferensbidrag (Refereegranskat)
    Abstract [en]

    In the present study, the recovery of rare earth elements (REE) in the nitrophosphate process of fertilizer production is investigated. The apatite has been recovered from iron ore tailings by flotation. After digestion of apatite in concentrated nitric acid, Ca(NO3)2.4H2O is first separated by cooling crystallization and then the REEs are recovered by precipitation. Optimum conditions in these steps have been determined in a previous study. The precipitate mainly consists of CaHPO4.2H2O and REE phosphates. In the present study, selective dissolution and re-precipitation have been studied in order to obtain a precipitate that is more concentrated in REEs. The precipitate was selectively dissolved in nitric and phosphoric acid at different acidities (pH 6 to 0) with the liquid /solid ratio of 100 mL/g. It is shown that most of the CaHPO4.2H2O and other calcium containing compounds will be dissolved at pH 2 while the REE phosphates are not dissolved above a pH of approximately 2. Thus, by partial dissolution of the REE precipitate at pH 2.5 most of the solid calcium phosphates will be dissolved and the remaining solid phase, which is more concentrated in REEs, can be filtered off as a fairly concentrated REE solid mass and the liquor can be recycled back to recover more P nutrients. Alternatively, the REE enriched precipitate was dissolved completely in nitric acid and re-precipitated again by addition of ammonium hydroxide to pH 1.2. A chemical equilibrium software, MEDUSA (Puigdomenech, 2013) has been used to evaluate the experimental results and to estimate the optimum conditions for selectively dissolving the precipitate. 

  • 41. Alfsen, K. H.
    et al.
    Bonifazi, C.
    Pedersen, A.
    Lindqvist, Per-Arne
    KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik.
    Electric field and plasma observations near the magnetopause and bow shock during a rapid compression.1984Ingår i: Achievements of the International Magnetospheric Study (IMS), s. 99-104Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A fast compressional motion of the magnetopause resulting from the interaction of an interplanetary shock and the Earth's magnetosphere is discussed. The ISEE-1 and 2 satellites were in the frontside magnetosphere before the shock. A magnetosonic wave front, the magnetopause, and the bow shock passed them in a very short time. By a combination of electric and magnetic field data it is possible to determine the magnetosonic and the magnetopause velocity. -from STAR, 23(14), 1985

  • 42. ALFSEN, KH
    et al.
    BONIFAZI, C
    PEDERSEN, A
    Lindqvist, Per-Arne
    KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik.
    INTERACTION BETWEEN AN INTERPLANETARY SHOCK AND THE EARTHS MAGNETOSPHERE ON AUGUST 27, 1978 - ISEE-1 ELECTRIC-FIELD AND ISEE-2 PLASMA OBSERVATIONS1984Ingår i: JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol. 89, nr NA10, s. 8863-8871Artikel i tidskrift (Refereegranskat)
  • 43.
    Alizadeh Khameneh, Mohammad Amin
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geodesi och geoinformatik.
    Tree Detection and Species Identification using LiDAR Data2013Självständigt arbete på avancerad nivå (masterexamen), 30 poäng / 45 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The importance of single-tree-based information for forest management and related industries in countries like Sweden, which is covered in approximately 65% by forest, is the motivation for developing algorithms for tree detection and species identification in this study. Most of the previous studies in this field are carried out based on aerial and spectral images and less attention has been paid on detecting trees and identifying their species using laser points and clustering methods.

    In the first part of this study, two main approaches of clustering (hierarchical and K-means) are compared qualitatively in detecting 3-D ALS points that pertain to individual tree clusters. Further tests are performed on test sites using the supervised k-means algorithm in which the initial clustering points are defined as seed points. These points, which represent the top point of each tree are detected from the cross section analysis of the test area. Comparing those three methods (hierarchical, ordinary K-means and supervised K-means), the supervised K-means approach shows the best result for clustering single tree points. An average accuracy of 90% is achieved in detecting trees. Comparing the result of the thesis algorithms with results from the DPM software, developed by the Visimind Company for analysing LiDAR data, shows more than 85% match in detecting trees.

    Identification of trees is the second issue of this thesis work. For this analysis, 118 trees are extracted as reference trees with three species of spruce, pine and birch, which are the dominating species in Swedish forests. Totally six methods, including best fitted 3-D shapes (cone, sphere and cylinder) based on least squares method, point density, hull ratio and slope changes of tree outer surface are developed for identifying those species. The methods are applied on all extracted reference trees individually. For aggregating the results of all those methods, a fuzzy logic system is used because of its good reputation in combining fuzzy sets with no distinct boundaries. The best-obtained model from the fuzzy system provides 73%, 87% and 71% accuracies in identifying the birch, spruce and pine trees, respectively. The overall obtained accuracy in species categorization of trees is 77%, and this percentage is increased dealing with only coniferous and deciduous types classification. Classifying spruce and pine as coniferous versus birch as deciduous species, yielded to 84% accuracy.

  • 44. Alm, L.
    et al.
    Farrugia, C. J.
    Paulson, K. W.
    Argall, M. R.
    Torbert, R. B.
    Burch, J. L.
    Ergun, R. E.
    Russell, C. T.
    Strangeway, R. J.
    Khotyaintsev, Y. V.
    Lindqvist, Per-Arne
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Rymd- och plasmafysik.
    Marklund, Göran
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Rymd- och plasmafysik.
    Giles, B. L.
    Differing Properties of Two Ion-Scale Magnetopause Flux Ropes2018Ingår i: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 123, nr 1, s. 114-131Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, we present results from the Magnetospheric Multiscale constellation encountering two ion-scale, magnetopause flux ropes. The two flux ropes exhibit very different properties and internal structure. In the first flux rope, there are large differences in the currents observed by different satellites, indicating variations occurring over sub-d(i) spatial scales, and time scales on the order of the ion gyroperiod. In addition, there is intense wave activity and particle energization. The interface between the two flux ropes exhibits oblique whistler wave activity. In contrast, the second flux rope is mostly quiescent, exhibiting little activity throughout the encounter. Changes in the magnetic topology and field line connectivity suggest that we are observing flux rope coalescence.

  • 45. Alsved, M.
    et al.
    Civilis, A.
    Ekolind, P.
    Tammelin, A.
    Andersson, A. Erichsen
    Jakobsson, J.
    Svensson, T.
    Ramstorp, M.
    Sadrizadeh, Sasan
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Strömnings- och klimatteknik. Lawrence Berkeley Natl Lab, Berkeley, CA USA.
    Larsson, P-A
    Bohgard, M.
    Santl-Temkiv, T.
    Londahl, J.
    Temperature-controlled airflow ventilation in operating rooms compared with laminar airflow and turbulent mixed airflow2018Ingår i: Journal of Hospital Infection, ISSN 0195-6701, E-ISSN 1532-2939, Vol. 98, nr 2, s. 181-190Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Aim: To evaluate three types of ventilation systems for operating rooms with respect to air cleanliness [in colony-forming units (cfu/m(3))], energy consumption and comfort of working environment (noise and draught) as reported by surgical team members. Methods: Two commonly used ventilation systems, vertical laminar airflow (LAF) and turbulent mixed airflow (TMA), were compared with a newly developed ventilation technique, temperature-controlled airflow (T(c)AF). The cfu concentrations were measured at three locations in an operating room during 45 orthopaedic procedures: close to the wound (<40 cm), at the instrument table and peripherally in the room. The operating team evaluated the comfort of the working environment by answering a questionnaire. Findings: LAF and T(c)AF, but not TMA, resulted in less than 10 cfu/m(3) at all measurement locations in the room during surgery. Median values of cfu/m(3) close to the wound (250 samples) were 0 for LAF, 1 for T(c)AF and 10 for TMA. Peripherally in the room, the cfu concentrations were lowest for T(c)AF. The cfu concentrations did not scale proportionally with airflow rates. Compared with LAF, the power consumption of T(c)AF was 28% lower and there was significantly less disturbance from noise and draught. Conclusion: T(c)AF and LAF remove bacteria more efficiently from the air than TMA, especially close to the wound and at the instrument table. Like LAF, the new T(c)AF ventilation system maintained very low levels of cfu in the air, but T(c)AF used substantially less energy and provided a more comfortable working environment than LAF. This enables energy savings with preserved air quality.

  • 46. Al-Yaarubi, A. H.
    et al.
    Pain, C. C.
    Grattoni, C. A.
    Zimmerman, Robert W.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Navier-Stokes Simulations of Fluid Flow Through a Rock Fracture2013Ingår i: Dynamic Fluids and Transport Through in Fractured Rock, American Geophysical Union (AGU), 2013, s. 55-64Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [en]

    A surface profilometer was used to measure fracture profiles every 10 microns over the surfaces of a replica of a fracture in a red Permian sandstone, to within an accuracy of a few microns. These surface data were used as input to two finite element codes that solve the Navier-Stokes equations and the Reynolds equation, respectively. Numerical simulations of flow through these measured aperture fields were carried out at different values of the mean aperture, corresponding to different values of the relative roughness. Flow experiments were also conducted in casts of two regions of the fracture. At low Reynolds numbers, the Navier-Stokes simulations yielded transmissivities for the two fracture regions that were closer to the experimental values than were the values predicted by the lubrication model. In general, the lubrication model overestimated the transmissivity by an amount that varied as a function of the relative roughness, defined as the standard deviation of the aperture divided by the mean aperture. The initial deviations from linearity, for Reynolds numbers in the range 1-10, were consistent with the "weak inertia" model developed by Mei and Auriault for porous media, and with the results obtained computationally by Skjetne et al in 1999 on a two-dimensional self-affine fracture. In the regime 10 < Re < 40, both the computed and measured transmissivities could be fit very well to a Forchheimer-type equation, in which the additional pressure drop varies quadratically with the Reynolds number.

  • 47.
    Ambell, Christine
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Industriell ekologi.
    Xu, Yixuan
    KTH, Skolan för industriell teknik och management (ITM), Industriell ekologi.
    Waste of Opportunities - A Holistic Study of the Current Situation of Municipal Waste Management in Shandong Province, China2009Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Kinas starka tillväxt håller på att skapa ett konsumtionssamhälle som påminner om det västerländska. Med högre konsumtion och starkare ekonomi växer avfallsmängderna snabbt. I Shandong provinsen finns mer än 90 miljoner invånare som varje dag gör sig av med 0,5 – 1,5 kg sopor. Det är en utmaning för samhällsplanerana och ingenjörerna att ta hand om dessa volymer. Hittills har det mesta av avfallet bränts på bakgårdar, kastas i vattendrag, ut i naturen eller lagts på deponi. Miljöskadorna är stora. Denna studie beskriver avfallshanteringens situtation i Shandong provinsen. Faktan är uppdelad utefter sociala, ekonomiska, tekniska och ekologiska parametrar. Studien täcker åren 2006 till 2010. Olika avfallsanläggningar och konstruktioner besöktes, utländsk litterlatur användes och en handledare från ett kinesiskt provinskonstruktionsföretag bidrog med information och data. Studien är delvis dokumenterad med foton. I diskussionen analysers styrkor, svagheter, möjligheter och hot med avfallshanteringen för överblick av situationen. I slutsatsen framgår det att det finns många möjligheter i utvecklingen av ett avfallshanteringssystem eftersom det är nytt, flexibelt och ekonomin är god. Det finns även hårda miljö och säkerheteslagar som påminner om EUs och USAs. Till hoten räknas stora avfallsvolymer som kan vara svårkontrollerade, samt att alldeles för hårda lagar kan hindra nya innovationer och teknik. Styrkor som finns är att fler än 111 stycken projekt är på gång, och att kunskap finns på högre ledningsnivå. Svageheterna är dålig implementering av lagar samt dålig kunskap på lägre nivå. Eftersom avfallhanteringen är i ett initierande stadie så kan de val som görs nu påverka på väldigt långt sikt.

  • 48.
    Amin, Hadi
    et al.
    Faculty of Engineering and Sustainable Development, The University of Gävle.
    Sjöberg, Lars
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Fastigheter och byggande, Geodesi och satellitpositionering. Faculty of Engineering and Sustainable Development, University of Gävle.
    Bagherbandi, Mohammad
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Fastigheter och byggande, Geodesi och satellitpositionering. Faculty of Engineering and Sustainable Development, The University of Gävle.
    A global vertical datum defined by the conventional geoid potential and the Earth ellipsoid parameters2019Ingår i: Journal of Geodesy, ISSN 0949-7714, E-ISSN 1432-1394Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The geoid, according to the classical Gauss–Listing definition, is, among infinite equipotential surfaces of the Earth’s gravity field, the equipotential surface that in a least squares sense best fits the undisturbed mean sea level. This equipotential surface, except for its zero-degree harmonic, can be characterized using the Earth’s global gravity models (GGM). Although, nowadays, satellite altimetry technique provides the absolute geoid height over oceans that can be used to calibrate the unknown zero-degree harmonic of the gravimetric geoid models, this technique cannot be utilized to estimate the geometric parameters of the mean Earth ellipsoid (MEE). The main objective of this study is to perform a joint estimation of W0, which defines the zero datum of vertical coordinates, and the MEE parameters relying on a new approach and on the newest gravity field, mean sea surface and mean dynamic topography models. As our approach utilizes both satellite altimetry observations and a GGM model, we consider different aspects of the input data to evaluate the sensitivity of our estimations to the input data. Unlike previous studies, our results show that it is not sufficient to use only the satellite-component of a quasi-stationary GGM to estimate W0. In addition, our results confirm a high sensitivity of the applied approach to the altimetry-based geoid heights, i.e., mean sea surface and mean dynamic topography models. Moreover, as W0 should be considered a quasi-stationary parameter, we quantify the effect of time-dependent Earth’s gravity field changes as well as the time-dependent sea level changes on the estimation of W0. Our computations resulted in the geoid potential W0 = 62636848.102 ± 0.004 m2 s−2 and the semi-major and minor axes of the MEE, a = 6378137.678 ± 0.0003 m and b = 6356752.964 ± 0.0005 m, which are 0.678 and 0.650 m larger than those axes of GRS80 reference ellipsoid, respectively. Moreover, a new estimation for the geocentric gravitational constant was obtained as GM = (398600460.55 ± 0.03) × 106 m3 s−2.

  • 49.
    Amin, Hadi
    et al.
    Faculty of Engineering and Sustainable Development, University of Gävle, 80176, Gävle, Sweden.
    Sjöberg, Lars E.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Fastigheter och byggande, Geodesi och satellitpositionering. Faculty of Engineering and Sustainable Development, University of Gävle, 80176, Gävle, Sweden.
    Bagherbandi, Mohammad
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Fastigheter och byggande, Geodesi och satellitpositionering. Faculty of Engineering and Sustainable Development, University of Gävle, 80176, Gävle, Sweden.
    A global vertical datum defined by the conventional geoid potential and the Earth ellipsoid parameters2019Ingår i: Journal of Geodesy, ISSN 0949-7714, E-ISSN 1432-1394, Vol. 93, nr 10, s. 1943-1961Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The geoid, according to the classical Gauss-Listing definition, is, among infinite equipotential surfaces of the Earth's gravity field, the equipotential surface that in a least squares sense best fits the undisturbed mean sea level. This equipotential surface, except for its zero-degree harmonic, can be characterized using the Earth's global gravity models (GGM). Although, nowadays, satellite altimetry technique provides the absolute geoid height over oceans that can be used to calibrate the unknown zero-degree harmonic of the gravimetric geoid models, this technique cannot be utilized to estimate the geometric parameters of the mean Earth ellipsoid (MEE). The main objective of this study is to perform a joint estimation of W-0, which defines the zero datum of vertical coordinates, and the MEE parameters relying on a new approach and on the newest gravity field, mean sea surface and mean dynamic topography models. As our approach utilizes both satellite altimetry observations and a GGM model, we consider different aspects of the input data to evaluate the sensitivity of our estimations to the input data. Unlike previous studies, our results show that it is not sufficient to use only the satellite-component of a quasi-stationary GGM to estimate W-0. In addition, our results confirm a high sensitivity of the applied approach to the altimetry-based geoid heights, i.e., mean sea surface and mean dynamic topography models. Moreover, as W-0 should be considered a quasi-stationary parameter, we quantify the effect of time-dependent Earth's gravity field changes as well as the time-dependent sea level changes on the estimation of W-0. Our computations resulted in the geoid potential W-0 = 62636848.102 +/- 0.004 m(2) s(-2) and the semi-major and minor axes of the MEE, a = 6378137.678 +/- 0.0003 m and b = 6356752.964 +/- 0.0005 m, which are 0.678 and 0.650 m larger than those axes of GRS80 reference ellipsoid, respectively. Moreover, a new estimation for the geocentric gravitational constant was obtained as GM = (398600460.55 +/- 0.03) x 10(6) m(3) s(-2).

  • 50. An, Lin
    et al.
    Yu, Xinhai
    Yang, Jie
    Tu, Shan-Tung
    Yan, Jinyue
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Energiprocesser.
    CO2 capture using a superhydrophobic ceramic membrane contactor2015Ingår i: CLEAN, EFFICIENT AND AFFORDABLE ENERGY FOR A SUSTAINABLE FUTURE, Elsevier, 2015, s. 2287-2292Konferensbidrag (Refereegranskat)
    Abstract [en]

    Wetting and fouling of membrane contactor result in performance deterioration of membrane gas absorption system for CO2 post-combustion capture of coal-fired power plants. To solve these problems, in this study, a superhydrophobic ceramic (SC) membrane contactor was fabricated by chemically modification using 1H, 1H, 2H, 2H-perfluorooctylethoxysilane (FAS) solution. The membrane contactor fabrication costs for both SC membrane and PP (polypropylene) membrane contactors per unit mass absorbed CO2 were roughly the same. However, by using the SC membrane, the detrimental effects of wetting can be alleviated by periodic drying to ensure a high CO2 removal efficiency (>90%), whereas the drying does not work for the PP membrane. The SC membrane contactor exhibited a better anti-fouling ability than the PP membrane contactor because the superhydrophobic surface featured a self-cleaning function. To ensure continuous CO2 removal with high efficiency, a method that two SC membrane contactors alternatively operate combined with periodic drying was proposed. (C) 2015 Published by Elsevier Ltd.

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