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  • 1.
    Abbas, Nahla
    et al.
    School of Engineering and Technology, Central Queensland University, Australia.
    Wasimi, Saleh A.
    School of Engineering and Technology, Central Queensland University, Australia.
    Al-Ansari, Nadhir
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Impacts of Climate Change on Water Resources in Diyala River Basin, Iraq2016Ingår i: Journal of Civil Engineering and Architecture, ISSN 1934-7359, E-ISSN 1934-7367, Vol. 10, nr 9, s. 1059-1074Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Diyala River is the third largest tributary of the Tigris River running 445 km length and draining an area of 32,600 km2. The river is the major source of water supply for Diyala City for municipal, domestic, agriculture and other purposes. Diyala River Basin currently is suffering from water scarcity and contamination problems. Up-to-date studies have shown that blue and green waters of a basin have been demonstrating increasing variability contributing to more severe droughts and floods seemingly due to climate change. To obtain better understanding of the impacts of climate change on water resources in Diyala River Basin in near 2046~2064 and distant future 2080~2100, SWAT (soil and water assessment tool) was used. The model is first examined for its capability of capturing the basin characteristics, and then, projections from six GCMs (general circulation models) are incorporated  to assess the impacts of climate change on water resources under three emission scenarios: A2, A1B and B1. The results showed deteriorating water resources regime into the future.

  • 2.
    Abbas, Nahlah
    et al.
    School of Engineering & Technology, Central Queensland University, Melbourne, Australia.
    Wasimia, Saleh A.
    School of Engineering & Technology, Central Queensland University, Melbourne, Australia.
    Al-Ansari, Nadhir
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Assessment of Climate Change Impact on Water Resources of Lesser Zab, Kurdistan, Iraq Using SWAT Model2016Ingår i: Engineering, ISSN 1947-3931, E-ISSN 1947-394X, Vol. 8, s. 697-715Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Kurdistan in northern Iraq, a semi-arid region, predominantly a pastureland, is nourished by Lesser Zab, which is the second major tributary of Tigris River. The discharge in the tributary, in recent times, has been experiencing increasing variability contributing to more severe droughts and floods supposedly due to climate change. For a proper appreciation, SWAT model has been used to assess the impact of climate change on its hydrological components for a half-centennial lead time to 2046-2064 and a centennial lead time to 2080-2100. The suitability of the model was first evaluated, and then, outputs from six GCMs were incorporated to evaluate the impacts of climate change on water resources under three emission scenarios: A1B, A2 and B1. The results showed worsening water resources regime.

  • 3.
    Abbas, Nahlah
    et al.
    School of Engineering & Techno logy, Central Queensland Univ ersity, Melbourne, Australia .
    Wasimia, Saleh A.
    School of Engineering & Techno logy, Central Queensland Univ ersity, Melbourne, Australia .
    Al-Ansari, Nadhir
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Assessment of Climate Change Impacts on Water Resources of Al-Adhaim, Iraq Using SWAT Model2016Ingår i: Engineering, ISSN 1947-3931, E-ISSN 1947-394X, Vol. 8, s. 716-732Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    SWAT model (Sediment and Water Assessment Tool) was used to evaluate the impacts of climate change on water resources in Al-Adhaim Basin which is located in north east of Iraq. Al-Adhaim River is the main source of fresh water to Kirkuk City, one of the largest cities of Iraq. Recent studies have shown that blue and green waters of the basin have been manifesting increasing variability contributing to more severe droughts and floods apparently due to climate change. In order to gain greater appreciation of the impacts of climate change on water resources in the study area in near and distant future, SWAT (Soil and Water Assessment Tool) has been used. The model is first tested for its suitability in capturing the basin characteristics, and then, forecasts from six GCMs with about half-a-century lead time to 2046-2064 and one-century lead time to 2080-2100 are incorporated to evaluate the impacts of climate change on water resources under three emission scenarios: A2, A1B and B1. The results showed worsening water resources regime into the future.

  • 4.
    Abbas, Nahlah
    et al.
    School of Engineering & Technology Central Queensland University, Melbourne, Australia.
    Wasimia, Saleh A.
    School of Engineering & Technology Central Queensland University, Melbourne, Australia.
    Al-Ansari, Nadhir
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Assessment of climate change impacts on water resources of Khabour in Kurdistan , Iraq using SWAT model2016Ingår i: Journal of Environmental Hydrology, ISSN 1058-3912, E-ISSN 1996-7918, Vol. 24, s. 1-21, artikel-id 10Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Khabour River is one of five tributaries of Tigris River and the first river flows into Tigris River contributing to Tigris Flow by about 2 BCM at Zakho Station. The area of this catchment is 6,143 km2, of which 57% are located in Turkey and 43% in Iraq with a total length of 181 km. Khabour River is the main source of fresh water to Duhok City, one of the major cities of Kurdistan Region. Hydrometeorological data over the past several decades reveal that the catchment is experiencing increasing variability in precipitation and stream flow contributing to more severe droughts and floods presumably due to climate change. SWAT model was applied to capture the dynamics of the basin. The model was calibrated at Zakho station. The performance of the model was rather satisfactory; R2 and ENC were 0.5 and 0.51, respectively in calibration period. In validation process R2 and ENC were nearly consistent. In the next stage, six GCMs from CMIP3 namely, CGCM3.1/T47, CNRM-CM3, GFDL-CM2.1, IPSLCM4, MIROC3.2 (medres) and MRI CGCM2.3.2 were selected for climate change projections in the basin under a very high emissions scenario (A2), a medium emissions scenario (A1B) and a low emissions scenario (B1) for two future periods (2046-2064) and (2080-2100). All GCMs showed consistent increases in temperature and decreases in precipitation, and as expected, highest rate for A2 and lowest rate for B1. The projected temperatures and precipitation were input to the SWAT model to project water resources, and the model outputs were compared with the baseline period (1980-2010), the picture that emerged depicted deteriorating water resources variability.

  • 5.
    Achleitner, Stefan
    et al.
    Unit of Hydraulic Engineering, University of Innsbruck.
    Schröber, Johannes
    AlpS - Centre for Climate Change Adaptation Technologies, Innsbruck.
    Rinderer, Michael
    Hydrology and Climate Unit, Department of Geography, University of Zurich.
    Leonhardt, Günther
    Unit of Environmental Engineering, University of Innsbruck.
    Schöberl, Friedrich
    Institute of Geography, University of Innsbruck.
    Kirnbauer, Robert
    Institute of Hydraulic Engineering and Water Resources Management, Vienna University of Technology.
    Schönlaub, Helmut
    TIWAG - Tiroler Wasserkraft AG.
    Analyzing the operational performance of the hydrological models in an alpine flood forecasting system2012Ingår i: Journal of Hydrology, ISSN 0022-1694, E-ISSN 1879-2707, Vol. 412-413, s. 90-100Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    During recent years a hybrid model has been set up for the operational forecasting of flood discharges in the 6750km 2 Tyrolean part of the River Inn catchment in Austria. The catchment can be characterized as a typical alpine area with large variations in altitude. The paper is focused on the error analysis of discharge forecasts of four main tributary catchments simulated with hydrological water balance models. The selected catchments cover an area of 2230km 2, where the non-glaciated and glaciated parts are modeled using the semi-distributed HQsim and the distributed model SES, respectively.The forecast errors are evaluated as a function of forecast lead time and forecasted discharge magnitude using 14 events from 2007 to 2010. The observed and forecasted precipitation inputs were obtained under operational conditions. The mean relative bias of the forecasted discharges revealed to be constant with regard to the forecast lead time, varying between 0.2 and 0.25 for the different catchments. The errors as a function of the forecasted discharge magnitude showed large errors at lower values of the forecast hydrographs, where errors decreased significantly at larger discharges being relevant in flood forecasting

  • 6.
    Addie, G.R.
    et al.
    GIW Industries Inc..
    Roudnev, A.S.
    Weir Minerals North America.
    Sellgren, Anders
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Weir Minerals North America2007Ingår i: Hydrotransport 17: the 17th International Conference on the Hydraulic Transport of Solids ; [7 - 11 May 2007, Cape Town, South Africa, South African Institute of Mining and Metallurgy, 2007, s. 205-218Konferensbidrag (Refereegranskat)
    Abstract [en]

    The Hydraulic Institute has completed the task of developing a new ANSI/HI standard 12.1-12.6 (2005) for rotodynamic (centrifugal) slurry pumps covering nomenclature, definitions, applications, and operation. The standard provides examples of the different slurry pump types and contains an extensive section on pump and slurry definitions. The effect of slurry on pump performance is covered along with the pumping of froth. Reference is also made to ANSI/HI standard 9.6.7 (2004), which contains a new method for pump performance correction when handling viscous fluids. Classification of slurry services is established and then is used to determine limitations on velocities and total head per pump in order to obtain acceptable wear performance. The new service class, head per stage and other limits are directly related to capital and other cost considerations that will affect solids transport system economics. The writers review the contents of the new standard, highlight the main points, and discuss the reason for the slurry classification, corresponding limits and expected implications, particularly with respect to operating costs of the pumps in solids transport systems

  • 7.
    Addie, Graeme
    et al.
    Engineering and Research and Development, GIW Industries Inc.
    Carstens, M.
    GIW Industries Inc..
    Sellgren, Anders
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Visintainer, R.
    GIW Industries Inc..
    Whitlock, L
    Hydraulic Test Lab., GIW Industries Inc.
    Pipeline design characteristics of some industrial paste-like slurries2005Ingår i: Conference Proceedings - First Extractive Metallurgy Operators' Conference, The Australian Institute of Mining and Metallurgy , 2005, s. 147-154Konferensbidrag (Refereegranskat)
    Abstract [en]

    There is a wide variety of industrial pastes or non-settling slurries pumped in mining, dredging and reclamation projects as products, refuse and tails. The types and/or names of some of the common ones are alumina red mud, phosphate clays, tar sands mature fine tails, tar sands (CT) consolidated clays and fly ash. The pipeline performance or friction of these varies dramatically with the type, its concentration and the particulars of the actual slurry making it difficult to select pumping equipment and to design associated pipelines. The GIW Hydraulic Laboratory in Grovetown Georgia has tested a number of these slurries over the last 30 years for various mining customers. Where available in the public domain and/or where permission has been obtained, the results of those tests are presented in this paper in a form usable for pipeline and pump system designers and users.

  • 8.
    Addie, Graeme R.
    et al.
    GIW Industries Inc..
    Roudnev, Aleksander S.
    Weir Minerals North America.
    Sellgren, Anders
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    The new ANSI/HI centrifugal slurry pump standard2007Ingår i: Journal of the South African Institute of Mining and Metallurgy, ISSN 0038-223X, Vol. 107, nr 6, s. 403-409Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Hydraulic Institute has completed the task of developing a new ANSI/HI standard 12.1-12.6 (2005) for Rotodynamic (Centrifugal) Slurry Pumps covering nomenclature, definitions, applications, and operation. The standard provides examples of the different slurry pump types and contains an extensive section on pump and slurry definitions. The effect of slurry on pump performance is covered along with the pumping of froth. Reference is also made to ANSI/HI standard 9.6.7 (2004), which contains a new method for pump performance correction when handling viscous fluids.Classification of slurry services is established and then is used to determine limitations on velocities and total head per pump in order to obtain acceptable wear performance. The new service class, head per stage and other limits are directly related to capital and other cost considerations that will affect solids transport system economics. The writers review the contents of the new standard, highlight the main points, and discuss the reason for the slurry classification, corresponding limits and expected implications, particularly with respect to operating costs of the pumps in solids transport systems.

  • 9.
    Addie, Graeme R.
    et al.
    GIW Industries Inc..
    Sellgren, Anders
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    A first slurry standard and some implications for paste application2007Ingår i: Paste 2007: proceedings of the tenth International Seminar on Paste and Thickened Tailings / [ed] Andy Fourie; Richard Jewell, Perth: Australian Centre for Geomechanics, 2007, s. 153-162Konferensbidrag (Refereegranskat)
    Abstract [en]

    The Hydraulic Institute has just completed the task of developing a new ANSI/HI standard on Rotodynamic (Centrifugal) Slurry Pumps covering nomenclature, definitions, applications, and operation. The standard provides examples of all the different types of pumps available and has an extensive section on definitions. Slurries and their effect on performance and wear are covered. A slurry service class is established which then is used to limit velocities and head produced per pump to give acceptable wear. A special section deals with mechanical seals and a new method for determining flange loads is presented and guidelines are given for commissioning, start-up etc.The head limits and the performance derating are of special interest when centrifugal slurry pumps are applied to thickened tailings and paste-like slurries. For Newtonian liquids, the Hydraulic Institute's Viscosity Correction Method (ANSI/HI 2004) provides a procedure widely used for viscous effects on the performance. For the homogeneous flow of viscous slurries, the new slurry standard refers to an applicable viscosity to use with the method and to "consult the pump manufacturer for guidance regarding non-Newtonian slurry pump performance."Experimental performance results are presented here and applied to the viscosity correction method for a simulated tailings product slurry characterized by a fully sheared yield stress of about 100 Pa, evaluated from pipeline data. The pump was a GIW-LCC type three-vane all metal unit with a 0.3m-diameter impeller having an open shroud with a simple auger-like inducer. Results are also given for an underground hydraulic fill product characterized by a Newtonian kinematic viscosity which is 1300 times that for water. The different results obtained here point out the strong influence the rheological behavior has on the choice of pump size and the power requirement.

  • 10.
    Addle, Graeme R
    et al.
    GIW Industries Inc..
    Sellgren, Anders
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Design, selection, sizing and control considerations for cyclone feed slurry pumps1999Ingår i: Powder Technology, ISSN 0032-5910, E-ISSN 1873-328X, Vol. 104, nr 3, s. 233-239Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cyclone feed centrifugal slurry pumps in semi-autogenous grinding (SAG) mill and other cyclone feed circuits see coarse size slurries at high concentrations that can result in high wear if the pump is not designed, selected, sized and operated correctly. The high proportion of static head of the normal cyclone feed circuits usually results in a relatively flat system curve which in conjunction with the typically flat slurry pump curve results in large changes in operating flow with small changes in system head. When this is combined with the normal (or abnormal) fluctuations in the output from the mill upstream of the pumps, any shortcomings in the pump control system and/or matching of the pump means large fluctuations in flow and increased wear. This difficulty could be corrected by continuous variations in speed. A means of control by which the speed is changed in an appropriate way is suggested here. In this case then the pump-input power, the known water performance of the pump and the system flow, can be used to calculate an effective pump discharge pressure. By comparison with a calculated system head, the pump speed can be regulated such that the pressures are equal and the system stable for any practical variation of incoming flow or specific gravity.

  • 11.
    Alere, Ilze
    Luleå tekniska universitet.
    Aspects of water quality dynamics in drinking water distribution systems1997Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
  • 12.
    Alere, Ilze
    et al.
    Luleå tekniska universitet.
    Hanaeus, Jörgen
    Particle dynamics in the drinking water distribution network of Luleå1997Ingår i: Vatten, ISSN 0042-2886, nr 4, s. 381-390Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [sv]

    Partikeldynamik i Luleås dricksvattennät

  • 13.
    Almqvist, Helena
    et al.
    Luleå kommun.
    Hanaeus, Jörgen
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Organic hazardous substances in graywater from Swedish households2006Ingår i: Journal of environmental engineering, ISSN 0733-9372, E-ISSN 1943-7870, Vol. 132, nr 8, s. 901-908Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The concentrations of several selected organic hazardous substances were investigated in domestic graywater. In total, 41 of 81 organic hazardous substances were found in concentrations above the detection limits (nonylphenol and octylphenol ethoxylates, brominated flame-retardants, organotin compounds, polyaromatic hydrocarbons, polychlorinated biphenyls, phthalates, linear-alkyl benzene sulfonate, and triclosan). Moreover, total solids, biochemical oxygen demand (BOD7), chemical oxygen demand (COD), total nitrogen, total phosphorus, potassium, and sulphur were investigated and presented for graywater. Another objective was to suggest potential household sources for a selected number of organic hazardous substances. The present and past investigations reveal households to be obvious contributors of organic hazardous substances to municipal wastewater, and that graywater is an important media in this transport. The spreading derives from diffuse household sources like everyday activities (laundry, cleaning, etc.), the wearing down of things such as pipe material and interior fittings, and from airborne deposition.

  • 14.
    Al-Rubaei, Ahmed
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Long-Term Performance, Operation and Maintenance Needs of Stormwater Control Measures2016Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
  • 15.
    Al-Rubaei, Ahmed
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Engström, Malin
    Växjö Municipality.
    Viklander, Maria
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Blecken, Godecke-Tobias
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Long-term hydraulic and treatment performance of a 19-year old constructed stormwater wetland: Finally maturated or in need of maintenance?2016Ingår i: Ecological Engineering: The Journal of Ecotechnology, ISSN 0925-8574, E-ISSN 1872-6992, Vol. 95, s. 73-82Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Constructed stormwater wetlands (CSWs) are a commonly used measure for stormwater retention and quality treatment. However, although questions have been raised about the long-term performance of CSWs, only a few studies have targeted this issue and none have evaluated the performance of CSWs more than approximately 5–10 years old. Further, most studies have not examined the development of the long-term performance of CSWs but delivered a snapshot at a certain point of time. The present study investigated the performance of a 19-year-old CSW in Växjö, Sweden, treating stormwater from a 320-ha urban catchment. Besides removal of sediment from the CSW’s forebay, no other maintenance had been conducted. However, regular inspections had been performed. The results of the present sampling campaign were compared to two existing datasets collected at the same CSW after three years of operation in 1997 and nine years of operation in 2003. The CSW was found to provide efficient peak flow reduction and, depending on the event characteristics, also volume reduction. It still treated stormwater effectively: removal of Cd, Cu, Pb, Zn, TSS and TP event mean concentrations were between 89 and 96%, whereas mean concentrations of TN were reduced by 59%. The load removal efficiencies were even higher. Comparative analysis of the three monitoring periods based on the load removal efficiency revealed that the CSW, despite the lack of maintenance, performed more efficiently and stably for most pollutants compared to when newly constructed. This underlines the importance of the establishment and maturation of constructed wetland systems. Overall, the results showed that CSWs are resilient systems, which if designed well and regularly inspected to prevent major issues, can work efficiently for at least two decades.

  • 16.
    Al-Rubaei, Ahmed
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Engström, Malin
    Växjö Municipality.
    Viklander, Maria
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Blecken, Godecke-Tobias
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Long-term hydraulic performance of stormwater infiltration systems: a field survey2013Ingår i: NOVATECH 2013: Planning and Technologies for Sustainable Urban Water Management, 23 - 27 June 2013, Lyon, France., 2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper examined the factors influencing the long-term hydraulic performance of some stormwater infiltration systems (swale and two types of permeable pavements) in Växjö, southern Sweden. The infiltration capacities of 9 permeable pavements and 2 swales sites, all with different ages ranging from 1 year to 14 years, were measured using replicate double ring infiltrometers. The sites were either constructed of swale (2), interlocking concrete pavers (ICP) filled with gravel (2), concrete grid pavers (CGP) filled with gravel (3), or concrete grid pavers (CGP) filled with grass (4). The results of this study showed that the long-term behaviour of the infiltration capacity relies largely on the type and age of the system and the type of joint filling (gravel and grass). Furthermore, the study showed that the 11 year old concrete grid pavers filled with grass had the highest infiltration capacity (4.80 + 2.46 mm/min), whilst the 9 and 14 year old swales had the lowest infiltration capacity (0.10 + 0.00 mm/min).

  • 17.
    Al-Rubaei, Ahmed
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Engström, Malin
    Växjö Municipality.
    Viklander, Maria
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Blecken, Godecke-Tobias
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Long-term treatment efficiency of a constructed stormwater wetland: preliminary results2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    Constructed stormwater wetlands (CSWs) are commonly used in Sweden and worldwide because of their high efficiency in urban stormwater management. However, questions have been raised about the long-term performance of CSWs. This study investigated the performance of a 19-year-old constructed wetland, which was designed to treat the stormwater from a 320-ha catchment located in the city of Växjö, southern Sweden. The system has not been maintained since its construction in 1994. The results of the present study were compared with results obtained from a previous study conducted by Växjö Municipality in 1997. The results showed that the CSW significantly reduced peak flows by 72%. High concentration reductions were found for Cd, Cr, Cu, Zn, Pb, TSS and TP (90, 89, 91, 90, 96, 96 and 86%, respectively). TN concentrations were reduced by 61%. The results indicated that lack of maintenance had no effect on the performance of wetland system during this long period of operation (19 years). In contrast, especially the removal of Cu and nitrogen was enhanced compared to 1997, which may be due to maturing of the system. The results show that CSWs are resilient systems, which (provided that design is sufficient) can work efficiently for at least two decades.

  • 18.
    Al-Rubaei, Ahmed
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Merriman, Laura S.
    Biological & Agricultural Engineering, North Carolina State University.
    Hunt, William F.
    Biological & Agricultural Engineering, North Carolina State University.
    Viklander, Maria
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Marsalek, Jiri
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Blecken, Godecke-Tobias
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Survey of the operational status of 25 Swedish municipal stormwater management ponds2017Ingår i: Journal of environmental engineering, ISSN 0733-9372, E-ISSN 1943-7870, Vol. 143, nr 6, artikel-id 05017001Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    During the past 50 years, wet stormwater ponds have been constructed to reduce negative environmental impacts of urban stormwater discharges on receiving aquatic environments. However, in many jurisdictions there is little information on the current operational status of such ponds and their functioning. This paucity of information prompted a field survey of 25 Swedish municipal stormwater ponds, aged between 3 and 26 years. The pond survey focused on estimating the pond hydraulic loading and efficiency, the state of littoral vegetation, characteristics of bottom sediment in the inlet and outlet zones (sizes and the chemistry), and the overall operational pond status, including the access for maintenance. The hydraulic efficiencies of ponds were estimated for pond footprint shapes and relative locations of the inlets and outlets using literature data. The estimated hydraulic efficiencies correlated well with the pond length-to-width ratios and the ratio of the pond surface area to the impervious area of the runoff contributing catchment (i.e., the hydraulic loading). Littoral vegetation was inspected visually and found to be overgrown at some facilities, which impeded the maintenance access. Benthic sediments in ponds contained silt and clay (&lt;63&#x2009;&#x2009;&#x3BC;m" role="presentation" style="box-sizing: border-box; display: inline; line-height: normal; word-spacing: normal; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;"><63  μm<63  μm), sand and gravel fractions, and when compared with the literature data, such sediments appeared relatively coarse. Chemical characteristics of sediments reflected anthropogenic (traffic) activities, but without excessive contamination warranting special disposal requirements. Of the 25 ponds surveyed, four were fenced off and inaccessible to machinery. In fact, the design of these four ponds was such that it made inspection and maintenance very difficult, which may pose potential risks to ponds operation. Fifty-four percent of the investigated ponds were in need of minor maintenance, primarily because of sediment and litter accumulation in their inflow and outflow sections. The fact that the inspection survey revealed relatively few minor issues that could be corrected easily demonstrates the importance of relatively simple regular inspections serving to detect minor problems at an early stage before they would seriously impact pond functioning. The above survey methodology should be helpful for developing similar low-cost surveys in other jurisdictions.

  • 19.
    Al-Rubaei, Ahmed Mohammed
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Engström, Malin
    Växjö Municipality.
    Viklander, Maria
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Blecken, Godecke-Tobias
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Effectiveness of a 19-Year Old Combined Pond-Wetland System in Removing Particulate and Dissolved Pollutants2017Ingår i: Wetlands (Wilmington, N.C.), ISSN 0277-5212, E-ISSN 1943-6246, Vol. 37, nr 3, s. 485-496Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study monitored the stormwater runoff quantity and quality treatment performance of a 6.8 ha 19-year old combined pond-wetland system, located in south Sweden, over one year. The mean volume reductions for 53 storm events for the pond and wetland were 40% and 28%, respectively, while the mean flow reductions were 60% and 76%, respectively. Pollutant concentrations in the influent to the wetland were highly variable. The pond-wetland system could efficiently remove an average of 91%, 80%, 94%, 91%, 83% and 92% of TSS, TP, particulate Cd, Cu, Pb, and Zn, respectively, whereas the removal of particulate and dissolved Ni was highly variable with an average of 67% ± 62% and −5% ± 41%, respectively. The removal of TN, NH4-N and NO3 + NO2-N was highly variable with an average of 45% ± 27%, 12% ± 96% and 45% ± 43%, respectively. These removal percentages are high in comparison to other studies and underline that relatively old systems can also provide efficient treatment. Although the pond accounted for a substantial reduction of pollutant concentration, the wetland significantly enhanced both the treatment performance and the peak flow reduction. This underlines that a combined pond/wetland system is a more beneficial solution than a pond only. The pollutant removal efficiency was significantly influenced by some factors including Antecedent Dry Days, seasonal variations, air temperature, retention times, rainfall depth and duration, and peak rainfall intensity.

  • 20.
    Al-Rubaei, Ahmed
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Stenglein, Anna Lena
    Blecken, Godecke-Tobias
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Viklander, Maria
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Can vacuum cleaning recover the infiltration capacity of a clogged porous asphalt?2012Ingår i: WSUD 2012: Water Sensitve Urban Design - 21 - 23 February 2012, Melbourne Cricket Ground : building the water sensitve community, Barton: Institution of Engineers, Australia , 2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    Objective: The main threat for the performance of porous asphalt is clogging leading to decreased infiltration capacity. Thus, we investigated the potential of vacuum cleaning to recover the infiltration capacity of clogged permeable asphalts which have been in use for several decades. The influence of road operation and maintenance measures on the results was discussed.Method: We investigated the hydraulic conductivity (HC) of two roads with porous asphalt in Haparanda and Luleå, Sweden, which had been in use for 28 years and 15 years, respectively. A lack of appropriate maintenance during their operating life had lead to significant clogging and thus malfunction. The roads were vacuum cleaned using a vacuum cleaner/sweeping truck combination. This technology is recommended as a maintenance option for porous asphalt. Before and after the vacuum cleaning, replicate HC measurements were conducted using double-ring infiltrometers.Result: Before vacuum cleaning, mean HC was <0.1mm/min in Haparanda and between 0.4 and 0.8 mm/min in Luleå. After vacuum cleaning, HC increased significantly in Luleå (between 1.1 and 7.1mm/min) while no significant increase was detected in Haparanda. Despite the improvement after vacuum cleaning, HC was still far lower than the initial HC after construction. Reasons for the different results in Haparanda and Luleå were identified; the road winter maintenance was of primary importance.Conclusion: Depending on the extent of clogging, vacuum cleaning has the ability to recover HC of porous asphalt. However, long term behaviour of the HC depends largely on the street maintenance, thus regular appropriate maintenance is preferable.

  • 21.
    Al-Rubaei, Ahmed
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Stenglein, Anna Lena
    Blecken, Godecke-Tobias
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Viklander, Maria
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Long-term performance of a porous asphalt pavement in Luleå, Sweden: preliminary results2011Konferensbidrag (Övrigt vetenskapligt)
  • 22.
    Al-Rubaei, Ahmed
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Stenglein, Anna Lena
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Viklander, Maria
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Blecken, Godecke-Tobias
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Long-term hydraulic performance of porous asphalt pavements in northern Sweden2013Ingår i: Journal of irrigation and drainage engineering, ISSN 0733-9437, E-ISSN 1943-4774, Vol. 139, nr 6, s. 499-505Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The effect of clogging on the long-term infiltration capacity and porosity of two 18- and 24-year-old porous asphalts was examined by using replicate double-ring infiltrometer tests and analyzing asphalt core samples. Tests were carried out to see if high pressure washing and vacuum cleaning could restore the hydraulic performance. The infiltration capacity of the porous asphalts decreased substantially, primarily due to surficial clogging (0.50 +/- 0.26 in Lulea, Sweden, and 0.22 +/- 0.12 in Haparanda, Sweden, compared to initially > 290 mm min(-1)). In Lulea, washing and vacuum cleaning could partially restore the infiltration capacity (3.48 +/- 3.00 mm min(-1)), but in Haparanda, no effect was measured. The porosity was constantly between 16 and 18%. The difference of the long-term behavior and effect of cleaning in Lulea and Haparanda is primarily attributable to different street maintenance, age, and winter maintenance (application of fine gravel and/or sand). Although the infiltration capacity in Lulea was far below initial values, the asphalt still has the capacity to infiltrate an intense design rainfall (100 year average return interval, 15 min duration), underlining that porous asphalt can be a resilient feature also under nonfavorable conditions

  • 23.
    Al-Rubaei, Ahmed
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Viklander, Maria
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Blecken, Godecke-Tobias
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Long-term hydraulic performance of stormwater infiltration systems2015Ingår i: Urban Water Journal, ISSN 1573-062X, Vol. 12, nr 8, s. 660-671Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Despite the common use of stormwater infiltration systems, there is still only limited data available evaluating the long-term hydraulic function of such systems. The hydraulic performance of twelve stormwater infiltration systems (vegetated and unvegetated concrete grid pavers, unvegetated interlocking concrete pavers and grassed swales) was therefore investigated in field and laboratory environments in Växjö, Sweden. The systems investigated had not been subjected to regular maintenance to sustain infiltration capacity. Due to this, and the fact that, for most systems, an inappropriate joint filling material was used and (at the swales) there was severe compaction, most systems showed a reduced infiltration capacity. Despite this, especially the older vegetated systems, were still capable of infiltrating intense design rainfalls. This study showed the influence of some factors (type and age of the system, the type of joint filling material (grass and macadam) and the distance from the edge of the pavement) on the long-term behaviour of the infiltration capacity. In conclusion, there is a significant risk that existing stormwater infiltration systems are not working adequately in praxis. Proper implementation of construction and regular control by the inspecting authority has to be ensured.

  • 24.
    Altorkmany, Lobna
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Kharseh, Mohamad
    Civil Environmental Engineering Department, Chalmers University of Technology.
    Ljung, Anna-Lena
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Lundström, Staffan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Experimental and Simulation Validation of ABHE for Disinfection of Legionella in Hot Water Systems2017Ingår i: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606, Vol. 116, s. 253-265Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The work refers to an innovative system inspired by nature that mimics the thermoregulation system that exists in animals. This method, which is called Anti Bacteria Heat Exchanger (ABHE), is proposed to achieve continuous thermal disinfection of bacteria in hot water systems with high energy efficiency. In particular, this study aims to demonstrate the opportunity to gain energy by means of recovering heat over a plate heat exchanger. Firstly, the thermodynamics of the ABHE is clarified to define the ABHE specification. Secondly, a first prototype of an ABHE is built with a specific configuration based on simplicity regarding design and construction. Thirdly, an experimental test is carried out. Finally, a computer model is built to simulate the ABHE system and the experimental data is used to validate the model. The experimental results indicate that the performance of the ABHE system is strongly dependent on the flow rate, while the supplied temperature has less effect. Experimental and simulation data show a large potential for saving energy of this thermal disinfection method by recovering heat. To exemplify, when supplying water at a flow rate of 5 kg/min and at a temperature of 50 °C, the heat recovery is about 1.5 kW while the required pumping power is 1 W. This means that the pressure drop is very small compared to the energy recovered and consequently high saving in total cost is promising.

  • 25. Altorkmany, Lobna
    et al.
    Nordell, Bo
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Overview of legionella bacteria infection: control and treatment methods2009Konferensbidrag (Övrigt vetenskapligt)
  • 26.
    Altorkmany, Lobna
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Nordell, Bo
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Overview of Legionella Bacteria Infection: Control and Treatment Methods2009Konferensbidrag (Refereegranskat)
    Abstract [en]

    Since the first recognized outbreak of Legionnaires' disease (LD) in 1976, it has become an increasing problem around the world especially in poor countries. Legionella (L) causes an estimated 15,000 annual cases of pneumonia in USA, and leads to death in about 20% of the cases. L is found worldwide in both natural and artificial environments e.g. spa pools, cooling towers. It infects people by inhaled contaminated aerosols that can transmit several km. The optimal temperature for L growth is 20-45C. Control of L is therefore an important health issue. Many treatment methods are used; biocides, ionisation, ozone, UV-radiation, pressure, and thermal treatment. Only thermal treatment can completely eliminate L, which is killed almost instantly at 70C. Current paper gives an overview of the Legionella problem and treatment methods.

  • 27.
    Amara, S.
    et al.
    Unité de Recherche en Energies Renouvelables en Milieu Saharien (URER/MS).
    Benyoucef, B.
    Unité de Recherche Matériaux et Energies Renouvelables (URMER), Université de Tlemcen.
    Nordell, Bo
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Touzi, A.
    Unité de Recherche en Energies Renouvelables en Milieu Saharien (URER/MS).
    Benmoussat, A.
    Unité de Recherche Matériaux et Energies Renouvelables (URMER), Université de Tlemcen.
    Experimental study of a concentration heating system with optical fiber supply2009Ingår i: Abstract book and proceedings : Effstock 2009: 11th International conference on Thermal Energy Storage for Energy Efficiency and Sustainability / [ed] Signhild Gehlin, Stockholm: Energi- och Miljötekniska Föreningen / EMTF Förlag , 2009Konferensbidrag (Refereegranskat)
    Abstract [en]

    The buildings thermal function is important to provide comfort to its tenants. This means to provide cooling during hot seasons and/or heating in cold season. Current study concerns modelling of a new design of thermal photo sensors that results in a more efficient heating for Tlemcen site, Algeria.

  • 28.
    Amara, S.
    et al.
    Unité de Recherche en Energies Renouvelables en Milieu Saharien (URER/MS).
    Benyoucef, B.
    Unité de Recherche Matériaux et Energies Renouvelables (URMER), Université de Tlemcen.
    Nordell, Bo
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Touzi, A.
    Unité de Recherche Matériaux et Energies Renouvelables (URMER).
    Benmoussat, A.
    Unité de Recherche Matériaux et Energies Renouvelables (URMER), Université de Tlemcen.
    Experimental study of a domestic hot water storage tank thermal behaviour2009Ingår i: Abstract book and proceedings : Effstock 2009: 11th International conference on Thermal Energy Storage for Energy Efficiency and Sustainability / [ed] Signhild Gehlin, Stockhiolm: Energi- och Miljötekniska Föreningen / EMTF Förlag , 2009Konferensbidrag (Refereegranskat)
    Abstract [en]

    Much work has been carried out on hot water storage during the last 20-30 years, particularly on solar heat applications. Theoretical and experimental studies on the internal heat transfer have been made at laboratory scale and at larger scales. Current study, which was conducted in order to understand the stratification phenomena, involved an experimental study on the thermal behaviour in a hot water tank during charging and discharging for domestic hot water storage. Results showed no effect of stratification due to the injection fluid from the bottom of the tank and the effect of mixed convection induced by the temperature difference which created a mixture inside the tank, where the temperature was uniform across the height, and the apparition of stratification due to the fact of discharge from the bottom of the tank.

  • 29.
    Amara, Saidi
    et al.
    Unité de Recherche Matériaux et Energies Renouvelables (URMER), Université de Tlemcen.
    Baghdadli, T.
    Unité de Recherche Matériaux et Energies Renouvelables (URMER), Université de Tlemcen.
    Nordell, Bo
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Khimulu, R.
    Unité de Recherche Matériaux et Energies Renouvelables (URMER), Université de Tlemcen.
    Solar System Design for Water Treatment: Antibacterial Heat Exchanger (ABHE)2017Ingår i: Innovative Healthcare Systems for the 21st Century / [ed] Hassan Qudrat-Ullah, Peter Tsasis, Springer International Publishing , 2017, s. 167-180Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    Current study concerns the fundamental problems to eliminate pathogens that are responsible for waterborne diseases. These illnesses, which have followed man throughout history, are described by occurring symptoms such as diarrhea and nausea. The various organisms identified within this document as waterborne bacterial pathogens are, e.g., Legionella (causes Pontiac fever), Salmonella (typhoid fever), and Yersinia (plague). Several control methods are available for water disinfection: biocide, ultraviolet light sterilization, copper–silver ionization, ozonation, etc., but only thermal treatment can eliminate bacterial pathogens, which are killed almost instantly at 70 °C. The current chapter describes water disinfection by a solar concentrator combined with a heat recovery system that reduces the heat demand. Though this study is made for a small system (160 l of hot water per day), the system can be enlarged (more hot water and more solar collector area), and the results are thus valid also for such larger systems. Here experiments of water treatment by a solar concentrator are summarized and analyzed where the temperature exceeds 80 °C at the outlet of the heat exchanger.

  • 30.
    Amara, Sofiane
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Corrigendum to “Using Fouggara for Heating and Cooling Buildings in Sahara” (Energy Procedia 6 (2011), 55–64)2011Ingår i: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 6, s. 825-Artikel i tidskrift (Refereegranskat)
  • 31.
    Amara, Sofiane
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Novel and ancient technologies for heating and cooling buildings2011Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The basic issue of this thesis concerns one of the fundamental problems of the future of our society: How to meet the energy requirements for a large and growing world population while preserving our environment? This question is important for the world and the answers are complex and interwoven.Conventional energy sources, fossil and fissile, are polluting in the present and in the future: they erode the environment and their resources are limited. Renewable energy (hydro, wind, solar, geothermal) constitutes a minimum of pollution in the different energy systems. The technologies for using renewable energy are well known though further development and progress are made. This development also requires behavioural change, adaptation, and above all political will. The transition from an economy based on fossil energy to an economy based on renewable energy appears necessary for the protection of the environment. The cost of renewable energy is often represented as an obstacle but remains competitive in the long run.The development and availability of renewable energy, which varies because of its spatial and temporal distribution, require an adaptation of lifestyle, habits, habitat design (passive bioclimatic houses), urban planning and transportation.The focus of this thesis was to apply renewable energy in an area with hot summers and cold winter, a climate like that in the northwest of Algeria. In order to provide improved comfort in the buildings and also economic development in this area, the energy demand for heating and cooling was analyzed in the ancient city of Tlemcen. To supply domestic hot water and space heating, water must be simultaneously available at two different temperature levels. Cold water temperature, close to that of the atmosphere, and hot water between 50 and 60°C. An interesting feature of the preparation of hot water is the small variation of requirements during the year, unlike that to heating. The preparation of hot water is one of the preferred applications of solar energy in the building for several reasons. For this reason an experimental study of the thermal behaviour of a domestic hot water storage tank was undertaken. The phenomena that affect the thermal behaviour of tank especially the coupling between the solar collector and storage tank was studied. This study included concentrating solar collector in which optical fibers were used to transport the energy to the storage tank. Another technology was introduced and developed for the heating and cooling of buildings in the desert involving an existing ancient irrigation system called Fouggara. The novel idea is to use the Fouggara as an air conditioner by pumping ambient air through this underground system. Then air at a temperature of about 21°C would be supplied to the building for heating in the winter and cooling in the summer. This study shows the feasibility of using this ancient irrigation system of Fouggara and contributes to reducing and eliminating the energy demand for heating and cooling buildings in the Sahara desert.

  • 32.
    Amara, Sofiane
    et al.
    Université de Tlemcen, BP 119 Tlemcen.
    Baghdadli, Tewfik
    Université de Tlemcen, BP 119 Tlemcen.
    Knapp, Samuel
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Nordell, Bo
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Legionella Disinfection by Solar Concentrator System2017Ingår i: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 70, s. 786-792Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The current study concerns the fundamental problems of Legionnaires disease. Four decades after Legionnaires' bacteria was first identified there is still a low level of clinical awareness. Humans are infected by inhalation of aerosolized water and/or soil contaminated with the bacteria. Several control methods are available for water disinfection: biocide, ultraviolet light sterilization, copper-silver ionization, ozonation etc. but only thermal treatment can completely eliminate Legionella, which is killed almost instantly at 70 °C. The current paper describes Legionella disinfection by a solar concentrator combined with a heat recovery system that reduces the heat demand. Though this study is made for a small system (160 l of hot water per day) the system can be enlarged (more hot water and more solar collector area) and the results are thus valid also for such larger systems. Here experiments of water treatment by a solar concentrator are summarized and analyzed where the temperature exceeds 80 °C at the outlet of the heat exchanger.

  • 33.
    Amara, Sofiane
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Benmoussat, A.
    Renewable Energy Research Unity in Saharien Middle, ‘URER/MS’.
    Benyoucef, B.
    Renewable Energy & Materials Research Unity, ‘URMER’.
    Nordell, Bo
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Requirements energy estimate of heating & cooling for a dwelling in the site of Tlemcen2007Artikel i tidskrift (Refereegranskat)
  • 34.
    Amara, Sofiane
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Nordell, Bo
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Benyoucef, B.
    Université de Tlemcen, BP 119 Tlemcen.
    Using fouggara for heating and cooling buildings in Sahara2011Ingår i: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 6, s. 55-64Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In order to utilise naturally stored heat or cold from the ground, seasonal temperature variations are required. The reason is that the ground temperature is then warmer than the air temperature during winter and colder during summer. The heating and cooling demand in North Africa varies considerably with the greatest cooling demand in the East and the greatest heating demand in the West. In parts of Algeria the mean temperature difference between the coldest and warmest month is greater than 20 °C, which is favourable. In current work it was shown that the ancient Fouggara system, even today would be interesting for heating and cooling of buildings in the Sahara desert.

  • 35.
    Amara, Sofiane
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Nordell, Bo
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Benyoucef, B.
    Université de Tlemcen, BP 119 Tlemcen.
    Benmoussat, A.
    Université de Tlemcen, BP 119 Tlemcen.
    Concentration heating system with optical fiber supply2011Ingår i: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 6, s. 805-814Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper reports on an experimental realization and field testing of a recently proposed solar fiber optic mini dish light concentrator connected to a hot water accumulator. The prototype dish is 150 cm in diameter. In repeated test the collected and concentrated sunlight was transported in a one millimeter diameter optical fiber to a selective surface in the storage tank. This surface absorbs the radiation which remains trapped inside as it heat exchanges with tank fluid which temperature can reach 70 °C.

  • 36.
    Amofah, Lea Rastas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    A small scale wastewater treatment system adapted to nutrient recovery in cold climate: performance and possible sorbents2007Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Waterbodies are impaired by, among other things, discharge from onsite small- scale wastewater (WW) treatment systems. Hence, these systems need to be updated to improve the effluent quality and the reuse of nutrients within society. The objectives of this thesis were to find suitable sorbents for a small scale WW treatment system, to investigate the performance of a willow bed in cold climate and to evaluate the function of a proposed WW treatment system adapted to sustainable development in cold climate.Column experiments were performed to study the ammonium adsorption and desorption of clinoptilolite. Laboratory scale studies were conducted to estimate the phosphorus (P) retention of blast furnace slag (BF slag). Further, a full-scale WW treatment system was implemented in northern Sweden to evaluate the function of the system and its units over 16 months. The system comprised of a willow bed and two parallel P filters, namely BF slag and Filtralite-P. A stream of primarily treated WW from a village was pumped to the treatment system.The results from the column experiments showed that ammonium adsorption of the studied clinoptilolite and the desorption of previously adsorbed ammonium was too low to be an economically reasonable alternative for WW ammonium retention in small-scale WW treatment systems.The investigated weathered and coarse-grained BF slag had a low WW P retention, with the overall P sorption below 100 mg P/kg. Therefore, the material is not suitable for P retention. Fresh and fine-grained BF slag demonstrated to be an effective P sorbent in laboratory experiments. However, the release of sulphuric compounds from the BF slag was extensive and may hinder its utilisation as P sorbent.Filtralite-P was found to be a promising P sorbent with a WW P sorption of about 370 mg P/kg at the end of the full-scale experimental period, and still with remaining capacity to retain P.The willow bed functioned as a treatment step due the reduction of nutrients, solids and BOD, and there was no significant difference in winter and summer performance. Climatic conditions seemed not to be a hindrance for willow beds in northern Sweden. However, the stemwood produced in the willow bed would replace only a small fraction of a household’s energy need for heating and warm water.In the full-scale study, the treatment system with BF slag filter attained neither of the protection levels given by Swedish Environmental Protection Agency (SEPA) during the experimental period. The Filtralite-P treatment line fulfilled the requirements of the low protection level by SEPA for the 1 year operating period and the requirements of the high protection level for 2 months. The need of maintanance in the studied treatment system was small and the operation was steady.

  • 37.
    Amofah, Lea Rastas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Towards sustainability of environmental protection: recovery of nutrients from wastewater filtration and the washing of arsenic contaminated soils2012Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Konventionella metoder för avloppsvattenbehandling och efterbehandling av förorenade områden fokuserar på att skydda människors hälsa, recipient och miljö. Därmed inriktar dessa metoder sig på att reducera och avskilja föroreningar och är därför inte lämpade att skapa resurser genom återvinning av näringsämnen, energi eller sanerade jordar. Därför riktar sig denna avhandling på en ny, mer hållbar strategi som inte enbart uppfyller miljöskyddskraven, utan även tar tillvara resurser som kan erhållas vid behandling. För att uppnå detta mål behövs en mer fördjupad kunskap om metoder för behandling av avloppsvatten och efterbehandling av förorenade jordar, utifrån resurshushållnings perspektiv.I denna avhandling utfördes laboratorie, pilotskale och fullskale försök för att studera fosfor (P) sorption i masugnsslaggfilter. Ammoniumadsorption och desorption från klinoptilolit undersöktes i kolonnförsök. En fullskaleanläggning för avloppsvattenbehandling som bestod av en salixbädd följd av två parallella fosforfilter med masugnsslagg och Filtralite® P sorbenter undersöktes med avseende på avloppsrening, upptag av näringsämnen i salixbiomassa och biomasseproduktion. På liknande sätt utfördes laboratorie-, pilotskale- och fullskaleförsök för att undersöka arsenik (As) avskiljning från As förorenade jordar m.h.a. fysisk separation och kemisk extraktion. Även rening av As förorenade extraktionslösningar undersöktes genom pH justering och tillsats av järnklorid.Resultaten visade att avskiljningen av ämnen i avlopp och As förorenade jordar påverkades av pH, innehållet av organiskt material, redoxpotential, tid och temperatur. Resultaten visade även att föroreningar i de studerade medierna hade komplexa egenskaper i form av ladding och redox speciering, och därmed kan inga generella slutsatser dras för alla studerade förhållanden. Masugnsslaggens sorptionskapacitet m.a.p. fosfor ändrades genom vittring och förvaring av material utomhus. Närvaro av organiskt material tycktes påverka ha en mer negativ påverkan på fosforsorption för den mer vittrade masugnsslaggen. Frigörandet av As från As förorenade jordar påverkades av pH, innehåll av organiska ämnen och redoxpotential, och karaktären av dessa effekter berodde på den kemikalie som förorenade jorden (impregneringsmedel) samt innehåll av kalcium i jorden. Extraktion i förhöjd temperatur ökade As mobilisering från förorenade jordarna för korta kontakttider, förutsatt att avgörande egenskaper för As mobilisering hos extraktionslösning inte förändrades. Den snabbaste mobiliseringen uppnåddesm.h.a. en sur oxalat-citrat lösning istället för reduktiva eller alkaliska extraktionslösningar.I fullskaleanläggningens salixbädd reducerades halten av suspenderat material och biologiskt nedbrytbart organiskt material effektivt från avloppsvattnet och förhindrade igensättning av de efterföljande fosforfiltren under ett års drift. Behandlingssystemet med filtermaterialet Filtralite® P avskiljde >90% organiskt material och 70% fosfor under den ett år långa försöksperioden, och uppfyllde därmed kraven för den normala skyddsnivån, förutom under snösmältperioden då kravet för tot-P inte uppnåddes. Dessutom uppfylldes kravet för tot-N reduktion (50%) för den höga skyddsnivån. För systemet med masugnsslagg uppfylldes däremot inte reningskraven, varken för normal eller hög skyddsnivå eftersom den grovkorniga slaggen var ineffektiv på att sorbera P och halterna av syreförbrukande ämnen var förhöjda i utflödet.De studerade metoderna för återvinning av resurser genom behandling av avloppsvatten och förorenad jord visade potential på resurshushållning genom dessa studerade processerna. Även om salixbädden inte ackumulerade näringsämnen från det inkommande avloppsvattnet i större grad, främjade den näringsupptag i efterföljande reningssteg. Färsk, finkorning masugnsslagg visade sig ha förmåga att sorbera P från avloppsvatten och kapaciteten var jämförbar med andra effektiva P sorbenter. Dock lakades signifikanta mängder svavelföreningar ut från filtret med masugnsslagg initialt vilket följaktligen ökade koncentrationen av syreförbrukande ämnen i filtrets utflöde. Därför rekommenderas inte användning av masugnsslagg som P sorbent när utflödet leds ut till känsliga recipienter. Den undersökta naturliga klinoptiloliten visade på hög ammoniumadsorptionskapacitet från förbehandlat avloppsvatten vid låga temperaturer. Därmed har klinoptilolit potential att öka N reduktionen från avloppsvatten under vintern eller före full etablering av salix när N reduktion krävs. Återvinningen av ammonium var dock begränsad p.g.a. låg desorption med kranvatten utan återföring av eluatet. Salix bevattnad med avloppsvatten växte nästan lika bra som i referensanläggningar i södra Sverige, men i den högbelastade salixbädden med horisontelt flöde var potentialen att producera biobränsle låg. För att återvinna näringsämnen förordas salixkloner med horisontell tillväxt. 90% av de ackumulerade näringsämnena i salixens växtdelar ovan jord kunde avlägnas från anläggningen som drevs under tre växtsäsonger, speciellt eftersom salixen var tätt planterad och skördandet genomfördes årligen innan löv fällningen. Att utesluta den fina jordfraktionen från kemisk extraktion var tillsammans med starka extraktionslösningar vid förhöjda extraktionstemperaturer ett effektivt sätt att tvätta jorden, även vid korta kontakttider. Denna behandling resulterade dock i en ofullständig återvinning av jorden (d.v.s. den behandlade jordmassan efter sanering var mindre än före sanering), förbrukade en stor mängd energi och minskade jordens kvalitet vilket i sin tur begränsar möjlig återanvändning av den behandlade jorden. Den alkaliska extraktionslösning som erhölls efter jordtvätt kunde behandlas vid pH 4-5 m.h.a. tillsats av en koagulant. Behandlingen av den alkaliska extraktionslösningen underlättades dessutom genom avskiljning av den fina jordfraktionen före kemisk extraktion. Sur oxalat-citrat extraktionslösning lämpar sig inte för behandling av As förorenade jordar eftersom en behandling med en sådan extraktionslösning är komplicerad p.g.a. hög pH buffrande och komplexbildande kapacitet.

  • 38.
    Amofah, Lea Rastas
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Hanaeus, Jörgen
    Nutrient recovery in a smallscale wastewater treatment plant in cold climate2006Ingår i: Vatten, ISSN 0042-2886, Vol. 62, nr 4, s. 355-368Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [sv]

    En småskalig avloppsanläggning har testats i Brändön norr om Luleå under ett år. 0,5 m3/d slamavskiljt vatten från samhället pumpades till försöksanläggningen som bestod av ett förfilter för att sprida vattnet följt av en sälgbädd och två paralella fosforfilter med Filtralite-P och masugnsslagg. I sälgbädden reducerades BOD7 med 80% medan fosfor- och kväveinnehållet minskade med 20-30%. Huvudsaklig mekanism bedömndes vara filtrering i bädden medan växtupptaget var av ringa storlek. Filtralite-P filtret reducerade BOD7 med 67%; fosfor och kväve med 72% och 20 respektive. Masugnsslaggen minskade fosforinnehållet med 53% och kväveinnehållet med 3%. BOD7-innehållet ökade däremot påtagligt genom slaggfiltret beroende på reducerade svavelkomponenter som frigjordes från slaggen. Systemet med Filtralite-P som adsorbent uppfyllde Naturvårdsverkets krav på normal men inte hög skyddsnivå. Systemet med BF slagg uppfyllde inte dessa krav.

  • 39.
    Amofah, Lea Rastas
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Mattsson, Jonathan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Hedström, Annelie
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Willow bed fertigated with domestic wastewater to recover nutrients in subarctic climates2012Ingår i: Ecological Engineering: The Journal of Ecotechnology, ISSN 0925-8574, E-ISSN 1872-6992, Vol. 47, s. 174-181Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Conventional methods for wastewater treatment emphasise protecting human health, receiving waters and the environment. Consequently, they are generally designed to reduce pollutant levels and are not well-suited for creating resources. This paper describes a new, more sustainable and energy-efficient approach to wastewater treatment that satisfies health and environmental standards while also facilitating resource recovery. A full-scale compact willow bed was intensively fertigated with domestic wastewater in a cold climate to examine biomass production, the recovery of nutrients in willow biomass, and wastewater treatment. The performance of the willow bed was assessed for two years, covering three growing seasons. The studied frost-tolerant willow clones produced good biomass yields per unit area (6–7 ton dry matter/ha and year) under intensive fertigation with dense planting and continuous harvesting. The biomass yield of willow species exhibiting vertical growth seemed to be greater than that for lateral growth species in the dense stands studied. In contrast to biomass production, nutrient recovery was facilitated by intensive fertigation, continuous harvesting and less dense planting with a horizontally growing willow clone. The estimated nitrogen accumulation in above-ground biomass was 210 kg/ha and that of phosphorus was 30 kg/ha. 90% of the accumulated nutrients in the above-ground biomass were removed from the site during the experimental period. However, the quantity of nutrients accumulated in the willow biomass represented only a small fraction of the loaded or removed amount. The willow bed was shown to be an efficient prefilter for reducing the abundance of particulate and organic matter, leaving the bulk of the remaining nutrients in forms that could be recovered in subsequent treatment steps.

  • 40.
    Amofah, Lea Rastas
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Maurice, Christian
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Bhattacharya, Prosun
    Kungliga tekniska högskolan, KTH.
    Chemical extraction of As from a polluted soil2008Ingår i: Arsenic in the environment - Arsenic from nature to humans: Book of Abstracts, 2008, s. 205-Konferensbidrag (Övrigt vetenskapligt)
  • 41.
    Amofah, Lea Rastas
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Maurice, Christian
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Bhattacharya, Prosun
    KTH-International Groundwater Arsenic Research Group, Department of Land and Water Resources Engineering, Royal Institute of Technology (KTH),.
    Extraction of arsenic from soils contaminated with wood preservation chemicals2010Ingår i: Soil & sediment contamination, ISSN 1532-0383, E-ISSN 1549-7887, Vol. 19, nr 2, s. 142-159Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Three soil samples contaminated by chromated zinc arsenate (CZA) or chromated copper arsenate (CCA) were investigated in a laboratory scale to study As mobilization and to identify a chemical agent that could be used in soil washing to extract arsenic. Besides high As extraction, the cost, occupational health issues and technical aspects were considered when selecting the chemical. Arsenic is strongly bound to CZA/CCA soils; only ∼50% of the tot-As was removed from water-washed soils. High Fe or Al mobilization is not necessarily indicative of high As removal from CZA/CCA soils. A high Cu/As-ratio and a large amount of soluble Ca in the soil hampered As extraction. The high ratio can be an indication of stable Cu-arsenates in soil. Calcium can react with the extraction agent or with As during extraction. Sodium hydroxide, dithionite with citrate (and oxalate) (dithionite solutions), and oxalate with citrate were the most efficient chemicals for removing As from the soils. The disadvantages of using these strong chemicals are: a high cost (oxalate with citrate); damage to equipment (dithionite solutions); an adverse impact on occupational health (dithionite solutions); or a deterioration in soil quality after extraction (NaOH and dithionite solutons). Phosphate, solutions based on NH2OH·HCl, or citrate were not efficient in mobilizing As from the soils.

  • 42.
    Andersson, Annika
    Luleå tekniska universitet.
    Kylvatten som värmekälla för begränsing av istryck mot dammluckor till kraftverk: en experimentell studie av fördelningssystem1990Rapport (Övrigt vetenskapligt)
  • 43.
    Andersson, Annika
    et al.
    Luleå tekniska universitet.
    Andersson, Lars-Olof
    Luleå tekniska universitet.
    A field study of frazil ice accumulation and adhesion on trash racks1992Rapport (Övrigt vetenskapligt)
    Abstract [en]

    A field experiment to study frazil ice blockage of water intake trash racks in hydropower plants is described. The experiment, conducted during the 1990/1991 winter using a submerged video camera, was designed to investigate ice accumulation on trash racks and compare this with laboratory tests. Differences between ice accumulation and adhesion on steel bars with and without a rubber coating were examined. The submerged video camera functioned well and was found to be an excellent tool to document and evaluate these ice phenomena. Frazil ice problems occured in air temperatures as high as -4°C. Frazil ice accumulation started on the upper section of the trash racks and progressed downwards. Ice was mainly deposited on the upstream face of the racks. The rubber coating material, with its poor adhesion to ice, appeared to mitigate frazil ice problems in the intakes in two ways. Ice was much more easily removed from trash rack elements coated with rubber and frazil did not stick to coated trash racks under small depress of supercoolings.

  • 44.
    Andersson, Annika
    et al.
    Luleå University of Technology.
    Svensson, Urban
    Luleå University of Technology.
    A numerical model of water droplet trajectories1989Ingår i: POAC '89: 10th International conference on port and ocean engineering under arctic conditions / [ed] Kenneth B.E. Axelsson; Lennart Å. Fransson, Luleå: Luleå tekniska universitet, 1989, Vol. 2, s. 671-680Konferensbidrag (Övrigt vetenskapligt)
  • 45.
    Andersson, Lars-Olof
    Luleå tekniska universitet.
    Adhesion of ice to polymer materials1989Ingår i: Poac 89: 10th International Conference on Port and Ocean Engineering under Artic Conditions, Luleå, Sweden, 12-16 June 1989 / [ed] Lennart Å. Fransson; Kennet B. Axelsson, Luleå: Högskolan i Luleå , 1989, Vol. 2, s. 786-985Konferensbidrag (Refereegranskat)
  • 46.
    Andersson, Lars-Olof
    Luleå tekniska universitet.
    Ice accretion and ice adhesion to polymer material1993Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
  • 47.
    Andersson, Lars-Olof
    et al.
    Luleå tekniska universitet.
    Golander, Car-Gustaf
    SKEGA AB.
    Persson, Sture
    SKEGA AB.
    Ice adhesion to rubber materials1994Ingår i: Journal of Adhesion Science and Technology, ISSN 0169-4243, E-ISSN 1568-5616, Vol. 8, nr 2, s. 117-132Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The aim of this study was to investigate the interfacial shear strength between ice and rubbers. Different rubber materials containing only a polymer and curing agent (peroxide) were tested with regard to surface wettability and interfacial shear strength. The effect of different grades and amounts of carbon black filler was also studied. The wettability was determined from contact angles, using water and diiodomethane as test liquids, measured on carefully cleaned and mirror smooth rubber sheets.

  • 48. Andersson, O.
    et al.
    Hellström, Göran
    Nordell, Bo
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Recent UTES development in Sweden2000Ingår i: Proceedings: TERRASTOCK 2000, 8th International Conference on Thermal Energy Storage : University of Stuttgart, Germany, August 28th until September 1st, 2000 / [ed] Martin Benner, Stuttgart: Universität Stuttgart , 2000, s. 75-80Konferensbidrag (Refereegranskat)
  • 49. Andersson, Olle
    et al.
    Johansson, Sam
    Nordell, Bo
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Innovative and cost-effective cold storage applications in Sweden: IEA Annex 71994Rapport (Övrigt vetenskapligt)
  • 50. Andersson, Olof
    et al.
    Hellström, Göran
    Nordell, Bo
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Heating and cooling with UTES in Sweden: current situation and potential market development2003Ingår i: Proceedings: Futurestock 2003, 9th International Conference on Thermal Energy Storage : Warsaw, Poland, September 1 - 4, 2003, Warszawa: PW Publishing House , 2003, s. 207-215Konferensbidrag (Refereegranskat)
    Abstract [en]

    Underground Thermal Energy Storage (UTES) applications have slowly gained acceptance on the Swedish energy market. Two UTES concepts are successfully implemented; the ATES (aquifer storage) and the BTES (borehole storage) systems. Also snow storage in pits or caverns has reached a commercial status. The number of ATES has steadily grown to 40 large-scale plants at the end of 2002. The systems are usually designed for cold storage in district cooling application, but industrial process cooling is also common. The economical potential in terms of straight payback time is usually very favourable. However, there is still a certain risk for operational problems that might jeopardize the calculated profit. Well clogging problems and system control remain as R&D issues to be solved. From a legislation point of view any ATES application needs a permit. The process of obtaining a permit has become complex and time-consuming since a new act on environmental assessment was put into effect in 1999.BTES systems are normally used in smaller applications. At the end of 2002 there were more than 200 installations comprising more than 10 boreholes. The majority of these are applied for space cooling of commercial or institutional buildings and for process cooling within the telecommunication sector. From a technical point of view, BTES are much simpler to construct and operate than ATES. Furthermore, they can be applied in almost any kind of geology. Another advantage compared to ATES is that the permitting procedure is much simpler. The major market obstacle is that the profitability is not always acceptable if calculated as a straight payback time. To increase the market potential, there is a need for further R&D on improvement of borehole heat exchangers and of more effective drilling methods.Snow storage is still a new technology though the Sundsvall snow storage plant has been operated successfully for several years. This good example has inspired several pre-studies of new snow storage plants. These have shown that snow storage is feasible in various sizes and in different applications.

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