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  • 51. Leduc, Sylvain
    et al.
    Schwab, Dagmar
    Dotzauer, Erik
    Mälardalen University, Department of Public Technology.
    Schmid, Erwin
    Obersteiner, Michael
    Optimal location of wood gasification plants under poly-production2007In: The 3rd International Green Energy Conference, 2007Conference paper (Other academic)
  • 52.
    Li, H.
    et al.
    Royal Institute of Technology, Stockholm, Sweden .
    Ji, X.
    Royal Institute of Technology, Stockholm, Sweden .
    Yan, Jinyue
    Mälardalen University, Department of Public Technology.
    A new modification on RK EOS for gaseous carbon dioxide2005In: ECOS 2005 - Proceedings of the 18th International Conference on Efficiency, Cost, Optimization, Simulation, and Environmental Impact of Energy Systems, 2005, p. 733-739Conference paper (Refereed)
    Abstract [en]

    Mitigation technologies including CO2 capture and storage in various energy conversion systems have been intensively developed in recent years. However, it is of importance to develop an equation of state (EOS) with simple structure and reasonable accuracy for engineering application for both pure CO2 and CO2 mixtures. In this paper, Redlich-Kwong equation of state was modified for gaseous CO2. In the new modification, parameter 'a' was correlated as a function of temperature and pressure from reliable experimental data in the range: 220K to 750K and 0.1MPa to 400MPa. To verify the accuracy of the new parameters, densities were calculated and compared with experimental data. The average error is 1.68 %. Other thermodynamic properties of CO2, such as enthalpy and heat capacities, were also calculated; results fit experimental data well except critical region. This method can be further developed for CO2 mixture systems.

  • 53.
    Li, H.
    et al.
    Royal Institute of Technology, Stockholm, Sweden.
    Ji, X.
    Royal Institute of Technology, Stockholm, Sweden.
    Yan, Jinyue
    Mälardalen University, Department of Public Technology.
    Quantitative evaluations on available models for calculating thermodynamic properties of humid air2005In: ECOS 2005 - Proceedings of the 18th International Conference on Efficiency, Cost, Optimization, Simulation, and Environmental Impact of Energy Systems, 2005, p. 889-896Conference paper (Refereed)
    Abstract [en]

    Engineering calculation of the thermodynamic properties for cycle simulation and design requires simple but reliable models. This has been proved to be of importance for the research and development on humidified gas turbines, such as humid air turbine (HAT) cycles and compressed air energy storage (CAES). This paper has made a comprehensive review and comparison among different models for calculating thermodynamic properties of the humid air mixtures, including ideal gas model (IG), ideal mixing model (IM), and real gas model (RG); and based on temperature and pressure range, gave quantitative evaluations on saturated water vapor composition and enthalpy. Based on performance conditions of an HAT cycle, several suggestions were given for the use of the today's available models for engineering cycle calculations, which can provide accurate results for cycle performance analysis and design while keeping the methods straightforward.

  • 54.
    Mousavi Takami, Kourosh
    Mälardalen University, Department of Public Technology.
    Temperature and heat losses simulation in core and winding of a power transformer2008Licentiate thesis, comprehensive summary (Other scientific)
    Abstract [en]

    “…A candle that burns twice as bright lasts half as long …” So too transformers can run at over rated loadings within limits, consequently shortening their expected service life.

     

    Power transformers are vital devices in power industries. Electrical utilities have to pay a significant portion of capital investment costs for Power transformers. Although the useful service life of transformer is around of 30 years, but some times utility needs to achieve over loading of transformers. It can decrease transformer expected life. Over loading and other problems make a hottest spot point in windings and core and as a result, these lead to insulation degradations, loss of life and cooling problems. There fore, here is an increased interest in safely utilizing all available capacity.

    In order to design a power transformer it is essential to understand its performance in loading times, same as hottest spot temperature, temperature profile in windings and losses. Exactly these can be obtained by measurements on physical transformers, analytical expressions and computer simulations. One important benefit on using of simulations before prototype is that the transformer can be modelled and simulated before it is built physically and that the consequences of varying dimensions and parameters easily can be tested.

     

    During the operation of power transformers, the critical parameter is the hottest temperature. The hot spot temperature (HST) has to be held under a prescribed limit. A cumulative effect of insulation aging, depending on time change of hot spot temperature, should be less than a planed value.

    Therefore, essentially utilities need to find a new method for hot spot detecting, monitoring and removing. In this thesis, I have suggested a new apparatus and system for hot spot point removing. The effects of oil spraying has been assessed, simulated and calculated. Using test data of 230/63/20kV Sari substation, simulation and calculation (using this device) have been performed; consequently it has been shown that electrical utility can mitigate the limitations of loading due to HST problem in transformers. Oil spraying system are investigated and modified to apply for local cooling. A robust algorithm have been proposed and trained for working out this task and are further optimally combined to give an improved accuracy.

    One important result of the thesis is the possibility to simulate temperature including the hot spot temperature and losses in the magnetic core material and windings.

     

  • 55.
    Mousavi Takami, Kourosh
    et al.
    Mälardalen University, Department of Public Technology.
    Mahmoudi, Jafar
    Mälardalen University, Department of Public Technology.
    Dahlquist, Erik
    Mälardalen University, Department of Public Technology.
    Process control in steel core production to reduce of power losses in electrical machines and transformers: Process Control2009In: Proceedings MATHMOD 09 Vienna, Vienna- Austria: Mathematical Modelling (MATHMOD) 2009 , 2009Conference paper (Refereed)
    Abstract [en]

    The main aim of cold rolling is reduction of strips to the desired final thickness. As the cold rolled strip is being manufactured from hot rolled strip, the uniformity of width, thickness, hardness, etc. are all now intended for improvement.  To reach to this target, need to abound control system to reach the higher quality of slabs.  It should satisfy the several factors, as regards geometrical, mechanical, chemical and surface properties.

    Process control has taken advantage of new measurement equipments, new control actuators and algorithms. Automation and automatic process control can advance the quality further than what is achievable by manual control. This is an important desideration in rolling industry that rolling of slabs needs advanced and optimized process control to increase the productivity and reduction of the variations in the final properties.

    A typical cold rolling stand performs one step in a chain of processes in the cold rolling mill, which can include pickling, rolling, annealing, temper rolling and downstream processes. All these processes contribute to the final properties of the strips. When the main process or the main objective is well controlled, it is important to continue with the other processes. In continuous annealing furnaces, the temperature controls the mechanical properties, but temperature differences and bending around rollers change the flatness. Temper rolling needs the same flatness control as other cold rolling processes. Cooling and lubrication can affect several properties of the strips.

    Precise general control of the strip in a cold steel rolling mill will be discussed in this article.

    Typically, the rolling process is modelled with numerical techniques. But these are not appropriate for a controller design, because they are too difficult. Thus, a linear mathematical model for the rolling process is presented here, which describes the interaction of the required influencing parameters. The attempt leads to numerically professional algorithms, which are essential to run in a real-time situation. With the help of these linear descriptions, the vital elements for the control are investigated. Modern rolling mills are equipped with a servo-hydraulic gap adjustment system, eccentricity control of the rolls, thickness, speed, force and tension controls.

    A model to optimize of the control design process and increasing of accuracy is presented. In this way using the process transfer function in system at different control mode like to thickness, flatness, shape and etc designed a PID and PI optimized controller with using of the best optimization method, final properties increased. The measurements are used to verify the model approach and to detect the most significant sources of disturbances.

    A new linearised numerical model for the rolling process which is suitable for closed loop control has been developed. The model is based on the calculation of the operating point using an available numerical method, followed by determining the partial derivatives at the operating point with respect to all input parameters. Finally, the partial derivatives are combined using superposition to describe the behaviour of the complete system. In this manner, the changes in the output parameters can be determined for small changes in the input parameters. This calculation is numerically efficient and suitable for use in closed loop control.

    Moreover, the roll eccentricity problem and the possibilities to perform compensation will be explained here. Due to the great variety of solutions, a classification of the methods will be sketched. The basic properties of these classes are discussed. Then, a special solution is presented, which has proved its worth already in a practical application. The investigation of its properties is proposed to be typical for the every class, to which the method belongs.

    Finally measurement data which can be used to verify the new model will be performed. The model has been incorporated as a simulation system developed by the authors who enable the simulation of a multi-pass single stand rolling process. To get practical information about the rolling process, a data logging system was developed and installed in Sura AB for data collection.

  • 56.
    Mousavi Takami, Kourosh
    et al.
    Mälardalen University, Department of Public Technology.
    Mahmoudi, Jafar
    Mälardalen University, Department of Public Technology.
    Dahlquist, Erik
    Mälardalen University, Department of Public Technology.
    Lindenmo, Magnus
    Surahammars Bruks AB, R&D.
    Evaluation of magnetic aging in transformers and electrical machines cores during operation: Modelling2009In: Proceedings of the Scientific Conference on Energy and IT at Älvsjö fair, Stockholm March 11-12, 2009 in connection with the “Energitinget 2009, 2009, p. 218-232Conference paper (Refereed)
    Abstract [en]

    Electric steels are processed to avoid the phenomenon known as magnetic aging. Non-oriented electrical steels are mostly used in rotating electrical machines and oriented steels used in transformers, which during operation generates heat. This could cause carbide precipitation/coalescence in the metallic matrix, impairing the magnetic properties of the steel, called magnetic aging. The steel has to contain very little carbon to avoid aging. This is achieved during the making of the steel or by a decarburising annealing of the final thickness strip or of the stamped laminations.

    The magnetic material for cores of a transformer and electrical machines should be characterised by high permeability and low energy losses in changing magnetic flux.

    In order to test that the magnetic properties do not become worse during these working conditions, the steel can be tested for magnetic ageing. The European standard defines the test cycle as 225°C for 24 hours. The American ASTM standard suggests two different cycles: 100 hours at 150°C or 600 hours at 100 °C.

     

    A test the losses after a heat treatment of 150°C f or 10 days for coils with higher carbon content than 26 ppm of the final product has performed here. This longer cycle has proved to give larger increases in the loss than the shorter one according to the European standard.

    The ageing process was much faster for a higher carbon content slab with 90 ppm C than for a lower one with 30 ppm C.

    ANN method using LMS has performed to aging real time identification. Results showed a 97% best fit. It showed that using ANN can predict the aging and a modern advanced relay can control the loading and temperature of electrical equipments to prevent of harmful damages.

  • 57.
    Nehrenheim, Emma
    Mälardalen University, Department of Public Technology.
    Metal retention from leachate using Industrial Waste Products2007Licentiate thesis, comprehensive summary (Other scientific)
    Abstract [en]

    Landfill leachate arises when water percolates through a landfill. The degree and type of pollution is dependent on the content of the landfill but also on a range of other factors, including the age of the landfill and the landfilling technique. In recent years, concerns about potentially hazardous compounds in landfill leachate have stimulated research into on-site treatment. Examples of new techniques for treatment are the sequent batch reactor technique (SBR), wetland systems and different forms of filter solutions.

    Lilla Nyby landfill is the municipal landfill in Eskilstuna, Sweden. Leachate streams have been found on site that are weaker than the main stream. One of these has been investigated in the present study. It contains heavy metals, especially zinc, copper and nickel, in concentrations which require treatment. Low strength landfill leachate streams require special treatment. There are various reasons for this, but examples can be geological reasons or dilution problems in the treatment facility for the main leachate.

    The technique chosen for the leachate stream, reactive filters, is rather new and few pilot scale experiments have been conducted. Therefore many questions still remain concerning the applicability of the method on site, and there was a need for more experimental data. Previous research has shown that many industrial by-products may be suitable to capture metals from leachate. Among the materials previously recommended, blast furnace slag and pine bark had advantages which were well suited for the present application. They were also available in large quantities near the site. A column experiment was set up at the landfill and three filter materials were chosen; pine bark and two types of blast furnace slag. In addition, one of the columns was filled with sand as a reference. As a complement to the column study, laboratory experiments were conducted at Mälardalen University. The aim of the laboratory experiments was to investigate factors that might limit metal retention by the filter materials. Different concentrations and contact times were tested as well as the presence of other substances (i.e. metals and organic carbon).

    The results from the first laboratory experiments (initial metal concentration, competing metal ions and contact time) and the on-site column study were contradictory. Metal uptake in the laboratory was very efficient, as has also been found by other researchers. On-site, many factors influenced sorption and uptake was very unstable, especially for the slags. It was found that pine bark is more effective and stable than the slags with respect to metal retention, especially at low concentrations. The contact time between the substrate and metals is important for effective retention. The final experiment, showed that dissolved organic carbon (DOC) can greatly inhibit metal retention. To further develop reactive filter technology, a method to reduce the DOC content may be necessary.

    In contrast to what has been previously assumed, leaching of COD from the pine bark column at Lilla Nyby landfill was negligible. Finally, some suggestions for future work on reactive filter technology are made. For instance, it could be interesting to develop an alternative technique for filtration. Packed columns have been addressed with a series of problems, related to hydraulic parameters. By using fluidised reactors, a comparison with batch experiments becomes possible.

  • 58.
    Nehrenheim, Emma
    et al.
    Mälardalen University, Department of Public Technology. Mälardalen University, School of Business, Society and Engineering.
    Gustafsson, Jon-Petter
    KTH.
    Kinetic sorption modelling of Cu, Ni, Zn, Pb and Cr ions to pine bark and blast furnace slag by using batch experiments2008In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 99, no 6, p. 1571-1577Article in journal (Refereed)
    Abstract [en]

    Storm water and landfill leachate can both contain significant amounts of toxic metals such as Zn, Cu, Pb, Cr and Ni. Pine bark and blast furnace slag are both residual waste products that have shown a large potential for metal removal from contaminated water. There are however many variables that must be optimized in order to achieve efficient metal retention. One of these variables is the time of which the solution is in contact with each unit of filter material. Metal sorption was studied in two laboratory experiments to improve the knowledge of the effects of contact time. The results showed that pine bark was generally more efficient than blast furnace slag when the metal concentrations were relatively small, whereas blast furnace slag sorbed most metals to a larger extent at increased metal loads. In addition, sorption to blast furnace slag was found to be faster than metal binding to pine bark. A pseudo-second-order kinetic model was able to describe the data well within 1000 s of reaction time. 

  • 59.
    Nehrenheim, Emma
    et al.
    Mälardalen University, Department of Public Technology.
    Waara, Sylvia
    Gustafsson, Jon-Petter
    Johansson Westholm, Lena
    The influence of dissolved organic carbon (DOC) on the metal sorption process to pine barkManuscript (Other academic)
  • 60.
    Nehrenheim, Emma
    et al.
    Mälardalen University, Department of Public Technology.
    Waara, Sylvia
    Johansson Westholm, Lena
    Mälardalen University, Department of Public Technology.
    Metal retention on pine bark and blast furnace slag - on-site experiment for treatment of low strenght landfill leachate2008In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 99, no 5, p. 998-1005Article in journal (Refereed)
    Abstract [en]

    Treatment of landfill leachate using blast furnace slag and pine bark as reactive sorbents was studied in an in situ column experiment at the Lilla Nyby landfill site in Eskilstuna, Sweden. The columns were filled with approximately 10 1 of each sorbent and leachate was supplied at three different flow rates during a period of 4 months. Samples of inflow and outflow were collected three times a week and were analyzed for physical and chemical parameters, including concentrations of some metals, and toxicity. It was found that pine bark removed metals more efficiently than did the blast furnace slags; that Zn was most efficiently retained in the filters and that both retention time and initial concentration played an important role in the sorption process. It was also observed that the pine bark column did not release COD. No toxicity of the untreated or the treated leachate was found with the test organisms and test responses used.  

  • 61. Nordlander, S
    et al.
    Persson, T
    Fiedler, Frank
    Mälardalen University, Department of Public Technology.
    Rönnelid, M
    Computer modelling of wood pellet stoves and boilers connected to solar heating systems2006In: Proceedings of the 2nd World Conference on Pellets 2006., 2006, p. 195-199Conference paper (Other academic)
  • 62.
    Nummelin, Maria
    et al.
    Mälardalen University, Department of Social Sciences.
    Almetun Englund, Britt
    Department of Public Technology.
    Kognitiv beteendeterapi i skolan2008Independent thesis Basic level (degree of Bachelor), 10 points / 15 hpStudent thesis
    Abstract [en]

    Syftet med studien var att få en ökad förståelse och insyn i vad kognitiv beteendeterapi- KBT är, och ta reda på om den stökiga skolmiljön som ofta förekommer, kan förbättras med hjälp av KBT. Våra forskningsfrågor behandlar: Vad är kognitiv beteendeterapi? Vilka förutsättningar krävs bland personalen för att arbeta med KBT vid en skola? När kan det vara lämpligt att pedagogerna i skolan använder sig av KBT? Hur använder pedagogerna KBT i skolan. Studien har genomförts genom bearbetning av relevant litteratur. En kvalitativ intervjuserie med olika pedagoger har genomförts och bearbetats. Resultatet av litteraturgenomgången och intervjuerna visade att KBT är en behandlingsmetod som har visat bra resultat för barn i behov av särskilt stöd i skolan. Dessa elever har visat en förbättring, som gör att de fungerar bättre i klassrummet. Kommunen använder KBT i skolorna genom att arbeta med skolgrupper som kommer att bestå av två KBT utbildade pedagoger på varje skola. Skolgruppens uppgift blir att tidigt och i förebyggande syfte, stötta och hjälpa i elevens sociala och känslomässiga utveckling. KBT pedagogerna har genomgått en viss utbildning i att arbeta med KBT. Det kan vara lämpligt att använda KBT i klasser där det finns störande och svaga elever.

  • 63.
    Nyström, Jenny
    Mälardalen University, Department of Public Technology.
    Fuel characterisation with radio-frequency spectroscopy2003Licentiate thesis, comprehensive summary (Other scientific)
  • 64.
    Nyström, Jenny
    Mälardalen University, Department of Public Technology.
    Methods for feed forward determination of moisture content in woodchips for power plants - state of the artIn: Fuel, ISSN 0016-2361, E-ISSN 1873-7153Article in journal (Refereed)
  • 65.
    Nyström, Jenny
    Mälardalen University, Department of Public Technology.
    Rapid measurements of the moisture content in biofuel2006Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    An increasing number of power plants in Scandinavia are beginning to use biofuel instead of coal or oil. The material in the new fuel is a mixture of woodchips, mostly Pine, Spruce and Salix, bark, GROT (tops and branches from felling waste) and sawdust from sawmills. It is heterogeneous, having a moisture content varying from 15% up to 65%. The moisture content affects the combustion of the fuel and therefore its commercial value. The industry is now interested in obtaining a method for measuring the moisture content of biofuel, quickly and reliably; preferably on delivery at the power plant.

    The measuring technique presented in this thesis is the first reported in the literature capable of measuring the moisture content of a large sample of such an heterogeneous material as biofuel. The equipment is today calibrated for a sample volume of 0.1 m3. A radio frequent signal is supplied from an antenna and penetrates the biofuel. Its reflection is modeled using partial least squares.

    As part of the work presented in this thesis, a new type of measuring rig and an analysis method for measurement of the moisture content of large samples of heterogeneous material have been developed. A statistical model for moisture content measurements of five different biofuel materials using radio waves has been built, having a root mean square error of prediction of 2.7. The interactions between biofuels and radio frequent signals have been demonstrated, indicating a variation of the reflection with varying types of biofuel material and variation in the reflection and delay of the signal with varying moisture content.

  • 66.
    Nyström, Jenny
    et al.
    Mälardalen University, Department of Public Technology.
    Axrup, Lars
    Dahlquist, Erik
    Mälardalen University, Department of Public Technology.
    Långtidsutvärdering av nya on-line fukthaltsmätare för biobränsle [Long-term evalution of on-line sensors for determination of moistrue in biomass]2002Report (Other academic)
  • 67.
    Nyström, Jenny
    et al.
    Mälardalen University, Department of Public Technology.
    Dahlquist, Erik
    Methods for determination of moisture content in woodchips for power plants - a review2004In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 83, no 7-8, p. 773-779Article in journal (Refereed)
  • 68.
    Nyström, Jenny
    et al.
    Mälardalen University, Department of Public Technology.
    Franzon, Bo
    Methods for Analysis of Radio-Frequency Measurements of Moisture Content in BiofuelManuscript (Other scientific)
  • 69.
    Nyström, Jenny
    et al.
    Mälardalen University, Department of Public Technology.
    Franzon, Bo
    Radio Frequency System for Measuring Characteristics of Biofuels2005In: IMTC 2005 – Proceedings of the IEEE Instrumentation and Measurement Technology Conference Ottawa, Canada, 17-19 May 2005, IEEE , 2005, Vol. 2, p. 978-983Conference paper (Refereed)
  • 70.
    Nyström, Jenny
    et al.
    Mälardalen University, Department of Public Technology.
    Thorin, E.
    Backa, S.
    Dahlquist, Erik
    Filling level measurement in woodchips bins with radio-frequency spectroscopy2003In: Nordic seminar on thermochemical conversion of biofuels, Nov. 12, 2002, 2003Chapter in book (Other academic)
  • 71.
    Nyström, Jenny
    et al.
    Mälardalen University, Department of Public Technology.
    Thorin, Eva
    RF-Measurements of Moisture Content of Biofuel using Time Domain SignalsManuscript (Other scientific)
  • 72.
    Nyström, Jenny
    et al.
    Mälardalen University, Department of Public Technology.
    Thorin, Eva
    Backa, Stefan
    Dahlquist, Erik
    Moisture Content Measurements on Sawdust with Radio Frequency Spectroscopy2005In: Proceedings of ASME Power, Chicago, Illinois, USA, April 5-7, 2005(2005), 2005Conference paper (Refereed)
  • 73.
    Odlare, Monica
    Mälardalen University, Department of Public Technology.
    Biogödsel och kompost - en resurs för jordbruket: Resultat från ett fältförsök2007Report (Other scientific)
    Abstract [sv]

    Syftet med ORC-försöket var att undersöka hur olika organiska gödselmedel med ursprung från både stad och land inverkar på markens kemiska, fysikaliska och mikrobiologiska egenskaper. Skördens mängd och kvalitet var en annan viktig faktor som studerades. De olika behandlingarna utgjordes av hushållskompost blandat med parkavfall, biogödsel från biogasframställning, rötslam från reningsverk, flytgödsel från svin samt fast gödsel från nötkreatur. Som en jämförelse fanns även ogödslade respektive handelsgödslade led med i försöket.

    Parcellerna lades ut i fältet efter noggranna studier med hjälp av NIR- (near infrared radiation) mätningar för att hitta försöksrutor som avvek så lite som möjligt från varandra avseende de fysikaliska markegenskaperna. Tillsatserna av de olika organiska restprodukterna skedde sen på ett sätt som i möjligaste mån skulle efterlikna bondens normala brukningsmetoder. De flytande gödselmedlena, dvs svingödsel respektive biogödsel från biogasrötning tillsattes på försommaren i växande gröda. Kompost, rötslam och kogödsel, som alla har en mer fast karaktär, tillsattes istället strax före plöjning på hösten. Jordprover för analys ca fyra veckor efter skörd.

    Förutom att studera diverse kemiska och fysikaliska mått, som pH, lerhalt, koncentrationer av kol, kväve, fosfor, svavel mm, användes även mikrobiologiska mått för att undersöka vilken effekt de olika gödningsmedlen hade på markegenskaperna. Markens mikroorganismer påverkas i hög grad av sin omgivning samtidigt som deras aktivitet har betydelse för markens odlingsegenskaper, till exempel vad gäller näringstillförsel och energiflöden. Att studera hur olika mikroorganism-grupper påverkas av de organiska gödningsmedlen kan alltså vara ett sätt att få ett mått på hur marken reagerar på tillsatsen av dessa. Mängden och kvaliteten på skörden från varje provruta analyserades dessutom årligen för att kunna jämföra den direkta gödslingseffekten av de olika tillsatserna på skördeutbytet.

    Resultaten från de långliggande fältförsöken visade att de organiska gödningsmedlen hade flera positiva effekter på såväl grödans tillväxt och kvalitet som markens kemiska och mikrobiologiska egenskaper. Inte i något fall observerades några direkta negativa effekter av vare sig kompost, biogödsel eller rötslam på markens produktivitet.

    I organiska gödningsmedel är näringsämnena inte alltid direkt tillgängliga för växtrötter och mikroorganismer utan frigörs allteftersom de omsätts i marken. Detta är en skillnad jämfört med handelsgödsel, där näringsämnena förekommer i mycket lättlöslig och lättillgänglig form. Vid användning av organiska gödningsmedel kan det därför ibland vara befogat att tillföra extra näringsämnen, framförallt kväve, för att tillgodose grödans behov, åtminstone de första åren innan ett kväveförråd hunnit byggas upp i marken. Komposten hade jämförelsevis lägst halt av lättillgängligt kväve, eftersom en del av detta förloras vid själva komposteringsprocessen. I en biogasprocess däremot, som sker i ett helt slutet system, förloras nästan inget kväve utan detta återfinns i slutprodukten. I ORC-försöket var det också biogödseln från rötning av källsorterat hushållsavfall som stod sig bäst i jämförelse med handelsgödsel i fråga om skördeutbyte och kvalitet. Biogödseln hade en positiv inverkan på flera av de mikrobiologiska aktiviteter som mättes i laboratoriet.

    Det är värt att notera att även rötslam från reningsverk, som ju debatterats en hel del, inte visade några negativa effekter på grödans tillväxt eller markmikroorganismernas aktivitet. Rötslammets innehåll av fosfor var högre än för de andra gödningsmedlen, däremot var kväveinnehållet inte lika högt som hos biogödseln.

  • 74.
    Paz, Ana
    et al.
    Mälardalen University, Department of Public Technology.
    Nyström, Jenny
    Thorin, Eva
    2006 IEEE Instrumentation and Measurement Technology Conference Proceedings2006In: IEEE Instrumentation and Measurement Technology Conference Proceedings, 2006, p. 175-179Conference paper (Refereed)
    Abstract [en]

    A method that permits the determination of moisture content in biofuel in a fast and representative way is under development. Vie method uses radio frequency waves within the range of 310 MHz to 800 MHz and measures the reflection coefficient in samples with volume of about 0.1 m(3). The influence of sample temperature in the measurements is shown in this study. Two biofuel types were used, with moisture content varying between 31% and 63% and temperature varying between 1 degrees C and 63 degrees C. The data was evaluated with multivariate data analysis. Results show that it is not possible to identify the sample temperature as a principal component in a principal component analysis and partial least squares regression shows no correlation between temperature and the radio frequency data. For the frequency interval and the temperature range studied, it was not possible to detect any influence of sample temperature on moisture content prediction with the radio frequency method.

  • 75.
    Pohl, Eva
    Mälardalen University, Department of Public Technology.
    Towards Corporate Sustainable Development: The ITT Flygt Sustainability Index2006Licentiate thesis, monograph (Other scientific)
    Abstract [en]

    This thesis suggests a method for measurement of corporate contribution to sustainable development, looking at how well a company stands up to its policies and commitments regarding sustainable development.

    A sustainability index is developed and calculated for ITT Flygt AB over a three years period (2002-2004). The index structure is based on scientific literature and interviews with ITT Flygt and four other engineering companies.

    The purpose of the index is to support corporate sustainability-management.

    The index is calculated by aggregating some forty sustainability-indicators. These indicators are individual to each company and are designed to measure the significant sustainability aspects of the company.

    Besides from providing one aggregated sustainability-value of the company, the index also provides sub-indices, which support the interpretation of the index result.

  • 76.
    pourian, bijan
    et al.
    Mälardalen University, Department of Public Technology.
    mahmoudi, jafar
    irwin, mark
    3-Dimensional numerical and analytical study of flow and thermal behavior of proposed mechanical fabrication copper heat sinkIn: Journal of green energyArticle in journal (Refereed)
  • 77.
    pourian, bijan
    et al.
    Mälardalen University, Department of Public Technology.
    mahmoudi, jafar
    irwin, mark
    Experimental determination of the thermal performance of a free standing fin2008In: The 49th Scandinavian Conference on Simulation and Modeling (SIMS 2008), 2008Conference paper (Refereed)
  • 78.
    pourian, Bijan
    et al.
    Mälardalen University, Department of Public Technology.
    mahmoudi, jafar
    irwin, mark
    Numerical and experimental study of the inclined free fins applied for thermal managementIn: International journal of numerical methods for heat & fluid flow, ISSN 0961-5539, E-ISSN 1758-6585Article in journal (Refereed)
  • 79. Ren, Xin
    et al.
    Zeng, Lei
    Mälardalen University, Department of Public Technology.
    Make CDM Work for Sustainable DevelopmentManuscript (Other academic)
  • 80.
    Ren, Xin
    et al.
    UNFCCC Secretariat, Germany.
    Zeng, Lei
    Mälardalen University, Department of Public Technology. Luleå University of Technology, Luleå.
    Zhou, Dadi
    Energy Research Institute, Beijing, China.
    Sustainable Energy Development and Climate Change in China2005In: Climate Policy, ISSN 1469-3062, Vol. 5, no 2, p. 185-198Article in journal (Refereed)
    Abstract [en]

    This article analyses the national circumstances and major factors underpinning China's energy demand and supply, energy-related emissions, and consequently China's sustainable development. These factors include the huge, still growing, and aging population, rapid economic growth, ongoing industrialization and urbanization, environmental and health concerns at local, regional and global level. Against such background analysis, the article explores the potential and constraints of non-fossil fuel, fuel-switching to natural gas, economy restructuring and clean coal technology in mitigating emissions of greenhouse gases (GHG) and ensuring energy supply in China. The authors reiterate the importance of improving energy efficiency in China and discuss how to integrate renewable energy into rural development. The article concludes with an in-depth discussion about redefining development goals, the equity issue in climate change process, and the linkage with sustainable development.

  • 81.
    Rüdén, Ulf
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Teknikundervisning utan könsroller2008Independent thesis Basic level (degree of Bachelor), 10 points / 15 hpStudent thesis
    Abstract [sv]

    Det här arbetet handlar till stor del om huruvida teknikundervisningen som genomförs i grundskolans senare del har påverkat flickors val av gymnasieutbildning. De flickor som går på typiska manliga utbildningar har varit utgångspunkt för den här studien. Antalet flickor som söker sig till dessa utbildningar är få, vilket framkommer i statistiken över förstahandsval till gymnasieutbildningarna som presenteras i undersökningen. Dessa elever har genom intervjuer fått möjlighet att berätta om varför de valt att gå de här utbildningarna. Val av gymnasieutbildning kommer i stor utsträckning att påverka dessa elevers framtida yrkesroller. Med detta i åtanke kommer även genusperspektivet i skola och yrkesliv att belysas. Läsaren får också en inblick i hur teknikundervisningen i grundskolan är uppbyggd och hur den genomförs i både teorin och praktiken.

    Genom att intervjuat 6 kvinnliga elever, som går på typiskt manliga gymnasieutbildningar, visar den här studien att teknikundervisningen i grundskolans senare del inte påverkat dessa elevers val av gymnasieutbildning.

  • 82.
    Sand, U.
    et al.
    Mälardalen University, Department of Public Technology.
    Bel Fdhila, Rebei
    Mälardalen University, Department of Public Technology.
    Numerical Modelling of Wood Particle Pyrolysis2009In: CONV-09. Proceedings of International Symposium on Convective Heat and Mass Transfer in Sustainable Energy, 2009Conference paper (Refereed)
    Abstract [en]

    This article provides a description of the modelling and simulation of the pyrolysis process of a small wood cylinder of 5.4mm height and diameter in a heating chamber containing nitrogen gas. The model considers forced and free convection inside and outside the particle. Convective, conductive and radiative heat transfer modes are included in this approach. The conversion from wood to char, tar and pyrolysis gas is modelled using a two-step reaction scheme.This approach offers a novel analysis advantage by involving simultaneously the particle and the surrounding atmosphere. This allows for a realistic prediction of the strong coupling between the inside and the outside of the particle. Earlier numerical works on pyrolysis of wood particles are generally considering the surrounding gas through the boundary conditions of the particle. Numerical results are successfully compared with measurements of the particle surface temperature profiles and the mass depletion rate at quiescent external flow. The influence of free and forced convection (0 ≤ ReD ≤ 135) on the overall pyrolysis time is investigated and a Nusselt number correlation is proposed. Based upon the results of the present investigation, a Nusselt number correlation accounting for the pyrolysis effects is proposed. The pyrolysis gas plumes can reach 0.1 m s−1. This is the same magnitude as the wood particles slip velocity in industrial applications. This reveals that in complex process situations as gasification or fluidized beds, the gas released by many small wood particles can strongly influence the dispersion characteristics. However, this study shows that the rocket force magnitude is significantly smaller than the drag and buoyancy forces.

  • 83.
    Sand, Ulf
    Mälardalen University, Department of Public Technology.
    Dynamics of wood particle pyrolysis applied to gas-solids fluidisation2005Doctoral thesis, monograph (Other scientific)
    Abstract [en]

    This thesis presents modelling and simulation aspects and results concerning pyrolysis of wood solids. The presented investigations are focused mainly on two processes; pyrolysis of single wood solids and pyrolysis of wood particles exposed to different levels of fluidisation.

    The studies presented begin with the modelling of single solids pyrolysis using both a twophase transport model and the porous media transport model. These are two equation approaches to model the mass, heat and momentum transport connected with the pyrolysis of the wood. A novel modelling feature in the present work is that the inner, the outer and the boundary layers of the heating and reacting wood solids are considered giving new possibilities to further investigate the pyrolysis phenomena. The models include the transition of important parameters during the decomposition of the wood structure, such as: density, thermal conductivity, mass diffusivity, porosity, permeability and emissivity. The simulation results are compared with experimental data from literature.

    Further on, resolving of the solids boundary layers allows for new models to be developed concerning mass, heat and momentum transport through the solids surfaces interface. Correlations are made for both the particle Nusselt and Sherwood numbers and a pyrolysis induced diffusivity and drag model is also created.

    From the studies on the pyrolysis of the single wood solids the impact of the pyrolysis is incorporated in the modelling of gas-solids fluidised systems with pyrolysing wood particles. The simulation of the particulate flow is modelled as two-phase flows where the rheology of the fluidised particles is taken into account by the use of the kinetic theory model approach. Two cases are presented concerning this type of process, the first is the model of the municipal circulating fluidised bed in Västerås in Sweden and the second is a numerical investigation of the impact of the authors developed correlations for mass, heat and momentum transfer of the pyrolysing solids.

  • 84.
    Sand, Ulf
    et al.
    Mälardalen University, Department of Public Technology.
    Sandberg, Jan
    Mälardalen University, Department of Public Technology.
    Bel Fdhila, Rebei
    Mälardalen University, Department of Public Technology.
    Two-phase transport model for the pyrolysis process of a vertical dry wood cylinder, including the surrounding flow field2006In: International Journal of Green Energy, ISSN 1543-5075, Vol. 3, no 1, p. 63-78Article in journal (Refereed)
    Abstract [en]

    This paper describes a mathematical model for the pyrolysis of a small dry pine wood cylinder. The computational domain is axisymmetric and involves the heating chamber, with the wood cylinder vertically situated in the centre of the chamber. The model simulates the laminar flow around the particle and the laminar flow inside the wood/char matrix by applying a two-phase transport model where the solid wood/char matrix acts as one phase and the various gases produced from the pyrolysis process is assembled in the other phase.

    Convective, conductive and thermal radiation transfer modes are included in the model. A two-step pyrolysis reaction scheme is used for the modelling of the conversion from wood to tar and gas. Both the thermal conductivity and the permeability of the wood/char matrix are modelled anisotropically in order to capture the directional differences in heat and mass transport, existing in real wood.

    Results from simulations are compared with measurements from literature for the centre core solid temperature and the conversion from wood to char, tar and pyrolysis gas in the particle during heating. The results show very good agreement with the measured temperature profile. The simulated conversion profile shows an overall good agreement with the measurements, however with discrepancies in the early stage of the process. Besides the successful validation with the experimental data, it provides us with all the details of the distribution of the migrating pyrolysis gas and tar, the temperature, the velocity flow field and pressure in the wood/char cylinder.

  • 85.
    Sandberg, Jan
    Mälardalen University, Department of Public Technology.
    Fouling in biomass fired boilers2007Licentiate thesis, comprehensive summary (Other scientific)
    Abstract [en]

    In order to reduce the discharge of the greenhouse gas CO2, the use of biomass is nowadays promoted as fuel in boilers. Compared to boilers fired with coal and oil the biomass-fired boilers have more complications related to both fouling and corrosion on the heat transfer surfaces. After the combustion, unburned inorganic matter in state of vapour, melts and solid particles are transported in the flue gas and may form deposits on heat transfer surfaces.

    Deposits on the heat transfer surfaces may result in both increasing corrosion and decreasing boiler efficiency as the heat transfer rate to the superheaters and reheaters decrease by deposits.

    In order to understand the process of deposit build-up, the whole combustion and transport process had to be analysed including aspects such as, boiler design, fuel properties and combustion environment, followed by particle transport phenomena and the probability for particles to get stuck on the heat transfer tubes.

    In this thesis numerical simulation of particle trajectories has been conducted as well as measurements of deposits on a special designed deposit probe followed by investigation of on-site measurements of deposit depth on the super-heater tubes in a circulating fluidised bed in Västerås, Sweden.

    Numerical simulations of particle trajectories in the vicinity of two super-heater tubes were conducted in an Eulerian-Lagrangian mode considering the flue gas and ash particles phase. Particle impingements on the tubes were investigated for different particle sizes. The results from the particle trajectory simulations show that particle larger than 10 µm will mainly impinge on the windward side of the first tube but, however also on the sides of the second tube in the flue gas flow direction. In theory as well as from observations and measurements two tubes can merge together by the deposit build-up. Smaller particles are usually more dispersed due to turbulence and thermophorectic forces, resulting in a more even impingement distribution on the whole surface of the tubes.

    Probe measurements reveal that the deposit layer growth rate have a significant temperature and time dependence. After the initial deposit build-up a sintering process occurs and sintering is also proven to be dependent on temperature and exposure time.

    Soot-blowing is the most common method to reduce the effect of deposits on the heat transfer tubes. In the present thesis the soot boiling efficiency is therefore also investigated. The soot-blowing show a strong positive effect on the heat transfer rate in a short time (hours) perspective after a soot-blowing cycle is completed. This positive effect is much weaker when considering a time period of three years. This is an effect of fact that soot-blowing mostly remove the loose part of the deposit material leaving the hard sintered part unaffected.

    The subject of deposit build up on superheater tubes in large scale boilers involves multi-discipline knowledge and historically, the related research is mostly conducted as measurements and experiments on operating plants. Possibly in the future, theoretical simulations will have a bigger part of research on deposit build-up where the calculations are to be calibrated through measurements on real sites plants.

  • 86.
    Sandberg, Jan
    et al.
    Mälardalen University, Department of Public Technology.
    Sand, Ulf
    Mälardalen University, Department of Public Technology.
    Bel Fdhila, Rebei
    Mälardalen University, Department of Public Technology.
    Long time investigation of the effect of fouling on the super-heaters in a circulating fluidised biomass boiler2006In: International journal of energy research (Print), ISSN 0363-907X, E-ISSN 1099-114X, Vol. 30, no 13, p. 1037-1053Article in journal (Refereed)
    Abstract [en]

    The present investigation involves measurements and theories on the mechanisms of the forming of deposit layers on super-heater tubes in a biomass-fired CFD boiler. The deposit layer thickness and the soot-blowing frequency effect on the super-heaters heat transfer are the main subject of the study that has been conducted over a 3-year period. The measurements show a deposit growth rate on the super-heaters of approximately 4 g m−2 h−1. The distribution of the deposit material varies significantly between the windward and the leeward side of the tubes, with the thickest layers on the windward side. Further down stream of the first super-heater, the fouling problem on the super-heater and re-heater tubes are not so severe. A theoretical model shows that a deposit layer of 20 mm will decrease the heat transfer rate of the first super-heater by nearly 40%. The soot-blowing system shows a strong positive effect on the heat transfer rate of the super-heater a few hours after a soot-blowing sequence has been completed. However in the long run, the varied soot-blowing frequency does not have a significant influence on the deposit layer growth rate.

  • 87.
    Sandberg, Jan
    et al.
    Mälardalen University, Department of Public Technology.
    Sand, Ulf
    Bel Fdhila, Rebei
    Measurements, theories and simulations of particle deposits on super-heater tubes in a CFB biomass boiler2006In: International Journal of Green Energy, ISSN 1543-5075, E-ISSN 1543-5083, Vol. 3, no 1, p. 43-61Article in journal (Refereed)
    Abstract [en]

    The present investigation involves theories, simulations and experiments on deposit layers on super-heater tubes in a circulating fluidised bed in Vdsteras in Sweden. Simulation of particle trajectories in the vicinity of two super-heater tubes is conducted in a Eulerian-Lagrangian mode for the flue gas and the ash particles from the combustion process. Particle impingements on the tubes are investigated for different particle sizes. Measurements of the buildup of deposit layers in the super-heater environment are conducted using a deposit probe. Deposit layer growth and growth rate is analysed for different probe temperatures, as well as the aspect of sintering on the probe ring surface. Analysis of the probe deposit material and deposits from the super-heaters and from textile filters are chemically analysed. The temperature dependence of the deposit materials viscosity is predicted from the chemical analysis of the samples. A model is included to simulate the effect of the deposit layer thickness on the tube heat exchange. The results from the particle trajectory simulations show that particle larger than 10 mu m will mainly impinge on the front of the first tube and that smaller particles are more dispersed due to turbulence and thermophorectic forces, enabling a more even impingement on the whole surface of the tubes. The probe deposit layer growth measurements show significant temperature dependence. The deposit material sintering and distribution is proven to be dependent on; temperature, particle size and exposure time. The stickiness of the deposit material is shown to be dependent on the SiO2 and alkali relation in the samples, estimated through a viscosity model.

  • 88.
    Sandberg, Jan
    et al.
    Mälardalen University, Department of Public Technology.
    Sand, Ulf
    Bel Fdhila, Rebei
    Numerical simulation of fouling on super-heater tube walls2002In: Proceedings of the 10th workshop on two-phase flow predictions, Merseburg, April 9 - 12, 2002Conference paper (Refereed)
  • 89.
    Sium, Sirak
    et al.
    Mälardalen University, Department of Public Technology.
    Stasais, Dimitrios
    Mälardalen University, Department of Public Technology.
    Mall förvaltningplan: Skolbyggnader2008Independent thesis Basic level (degree of Bachelor), 10 points / 15 hpStudent thesis
    Abstract [en]

    The aim of this thesis is to establish a “förvaltningsplans” template to Fastighetskontoret in Vasteras city. Further general information about the mission was given at our first meeting with Rolf Haraldsson, who happened to be our mentor and works at Fastighetskontoret in Vasteras city.

    We agreed that using the software Excel was the most appropriate way to establish the template, because Fastighetskontoret also make use of Excel in their internal system, and also because Excel has a more friendly user interface and it is more easier to use compared to other software that have complex templates.

    One of the first things we did was to get in contact with different fastighetskontors around Sweden so that we could either take part of their “förvaltningsplaner” or get referred to other material that could have been used. But this turned out to be an unsuccessful strategy. However, by searching on internet, course literature and databases we got a successful result.

    The most common headlines were included in the template and were later discussed with our mentor from Malardalen University, Sone Nydert. Mr. Nydert who gave us viewpoints and directions on how we should develop our work further.

    Thereafter, we had continual meetings with the mentor in Fastighetskontoret in Vasteras stad, Rolf Haraldsson, so that we could discuss and adjust the templates in line with the headlines in order for the template to match the fastighetskontorets internal headlines.

    The template was finally tested in frosundaskolan and turned out to be a successful work.

  • 90.
    Skogsfjord, Michael
    et al.
    Mälardalen University, Department of Public Technology.
    Blom, Minna
    Mälardalen University, Department of Public Technology.
    Masugnsslaggens potential som filtermaterial för metaller i vägdagvatten2008Independent thesis Advanced level (degree of Magister), 10 points / 15 hpStudent thesis
    Abstract [en]

    Stormwater from roads often contain heavy metals. The most common metals in storm water from roads are lead, copper, cadmium, nickel, and zinc. These pollutants constitute a stress for organisms in recipients that receive the stormwater. In this report lead, copper and zinc have been reduced from road storm water through filtration in columns with granulated iron slag and sand. Iron slag is a by-product from the iron making process, with a high sorption capacity, which makes it suitable as a filter material for water polluted with metals. The sand in this study has been used as reference material. The reducing capacity in the stormwater for the iron slag used in this study, “hyttsand”, was 79 % for lead, 82 % for copper and 92 % for zinc. The reducing capacity of the iron slag was also investigated in batch studies.

  • 91.
    Skogsfjord, Michael
    et al.
    Mälardalen University, Department of Public Technology. Mälardalen University, School of Sustainable Development of Society and Technology.
    Blom, Minna
    Mälardalen University, Department of Public Technology.
    Naturliga filtermaterial för reduktion av metaller i dagvatten2006Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Polluted storm water from a metal recycling industry has been filtrated through columns that contained two different adsorbents, peat and pine bark. Peat is an organic soil, mainly used for energy production, and pine bark, a by-product from the forest industry. In Sweden, there are a lot of resources of peat as well as pine bark. Used as filter materials, they are relatively cheep and, like other kinds of filtermaterial used as adsorbents, they have varied capacity to adsorb metals in water. The capacity for the filter materials to adsorb metals depends on the physical structure and chemical contents of the peat and pine bark as well as the water metal composition. Results from this study show that pine bark had the highest adsorption capacity to reduce copper, lead and zinc from the specific storm water.

  • 92.
    Starfelt, Fredrik
    et al.
    Mälardalen University, Department of Public Technology. Process and Resource Optimization.
    Yan, Jinyue
    Mälardalen University, Department of Public Technology. Royal Institute of Technology, Stockholm, Sweden.
    Case Study of Energy Systems with Gas Turbine Cogeneration Technology for an Eco-Industrial Park2007In: 3rd International Green Energy Conference: Proceedings of IGEC-III, 2007, 2007, p. 509-515Conference paper (Refereed)
    Abstract [en]

    Eco-industrial parks (EIP) are clusters of industry corporations that collaborate with reusing waste and energyefficient use of resources with no or minor impact on the environment. This paper presents a case study that examines the feasibility of using gas turbine technology in one industrial park, located in Dongguan city of Guangdong province in China.

    A model of a gas turbine based combined heat and power (CHP) plant with a heat recovery steam generator (HRSG) for absorption cooling was developed and simulated. A steam-injected gas turbine (STIG) has been selected in the system to increase electricity production while generating steam. The study includes performance analysis of the cogeneration plant in terms of thermal efficiency, cost estimation, and greenhouse gas emission. The gas turbine based cogeneration system has been compared to a baseline reference case that is defined as if all energy to the industrial park is supplied from the local electricity grid. The results show that the gas turbine based cogeneration system can reach a thermal efficiency of 58 % and reduce the CO2 emissions with 12,700 tons per year. A sensitivity analysis on the costs of the system has also been made based on fuel costs and interest rate which shows that the investigated system is economically profitable at natural gas prices below 4.4

    yuan/m³ with fixed electricity prices and at electricity prices above 736 yuan/kWh with fixed natural gas prices. The sensitivity analysis based on interest rate showed that the proposed system is economically feasible with interest rates up to 16 %.

  • 93.
    Stigson, Peter
    Mälardalen University, Department of Public Technology.
    Reducing Swedish Carbon Dioxide Emissions from the Basic Industry and Energy Utilities: An Actor and Policy Analysis2007Licentiate thesis, monograph (Other scientific)
    Abstract [en]

    The aim of the thesis is to analyze the design of the present climate and energy policies. The main focus is on how the policy instruments affect the Swedish stakeholders who are included in the European Union’s Emission Trading Scheme (EU-ETS). In-depth interviews have been carried out with representatives from the basic industry, energy utilities as well as industrial and green organizations. The purpose is to illustrate have how these stakeholders view the current policy framework and what amendments that they view as necessary.

    Suggestions to the Government are given regarding the design of national policies and policy instruments to provide for an improved policy framework. The information and synthesis have furthermore been collected through extensive literature studies as well as participating at conferences and seminars.

    The thesis is written as a monograph in order to address a larger group of readers interested in the transition of energy systems towards sustainability as well as policy makers and Swedish stakeholders. The common understanding that the global energy systems have to undergo a transition to renewables and higher energy efficiency due to the earth’s finite sources of fossil fuels and uranium presents large challenges for policy makers and business sectors as well as the society in general.

    Global greenhouse gas (GHG) emissions have to be drastically reduced and the work to achieve this has started through international negotiations such as the Kyoto Protocol. As the present commitment levels are low, an important issue in a short-term perspective is to develop a more comprehensive and efficient system with a much wider participation and more stringent emission targets.

    In order to achieve current national policy goals and international GHG emission commitments the Swedish Government utilizes a number of policy instruments that are either nationally self-assumed or called for by international agreements or the European Union. The Swedish stakeholders that are included in the EU-ETS face a broad policy framework that has a large impact on their daily operations and future investment strategies. It is imperative for the policymakers, i.e. the Government, to act in accordance with the long-term perspective that the climate change issue and the transition of the energy system require. It is likewise important that any actions are in accordance with the operational and investment climate that the business sector faces. It is argued that these aspects are not fully considered as the success of the next national budget or term of public office seems to overshadow these issues. A long-term perspective is required to provide the business sector with stable and reliable incentives. This is needed to provide the economic conditions under which the businesses can realize investments that will result in emission reductions. Short-term policies reinforce the view of environmental investments as a form of risk investments. This negatively affects the possibility of the policy instruments to effectively achieve established policy goals.

    Paying attention to these requirements is however not a simple task for policy makers as it will require agreements between the political parties. This demonstrates the main political difficulty with climate change – the requirement of a long-term and full commitment by all state authorities. It should be noted that the thesis does not attempt to describe the Swedish policy makers as neglecting the urgency of acting to mitigate climate change. The national agenda is far to advanced from an international perspective for such statements. The thesis however pinpoints some important issues highlighted by stakeholders, within the business sector and other organizations, who are concerned with the present climate and energy policy framework.

    Some of the findings are as follows:

    • Reducing GHG emissions in order to combat climate change must include a long-term perspective

    • The design of policy instruments should consequently be long-term to increase the support for investments in GHG emission reducing technologies

    • The design of policies that promote low GHG production alternatives within the energy utilities should be improved

    • The large potential for reduced GHG emission available through fuel switching and energy efficiency improvements in the Swedish basic industry should be promoted by amended policies

    • Reformulate or abandon the national GHG emissions target goal with the current formulation

    • Strive for an emission rights allocation system that is as transparent, fair and predictable as possible

    • The policy framework should aim for a high level of stability through interaction with the affected stakeholders

    • These factors are inherently important for the overall efficiency of the policy framework

  • 94.
    Tarzibachi, Mohammed
    Mälardalen University, Department of Public Technology. Mälardalen University, School of Sustainable Development of Society and Technology.
    IT som pedagogiskt verktyg i undervisningen: en fallstudie av en gymnasieskola2007Independent thesis Basic level (degree of Bachelor), 10 points / 15 hpStudent thesis
    Abstract [sv]

    Syfte: Syftet med detta examensarbete är att undersöka hur lärare upplever IT som pedagogiskt verktyg i undervisningen.

    Metod: För att svara mot frågeställningarna i denna undersökning har en fallstudie gjorts på Fröberg gymnasiet. Den kvalitativa undersökningen har skett via besöksintervjuer med åtta strategiskt utvalda respondenter.

    Resultat: Enligt respondenterna, i denna undersökning, finns det många fördelar med att använd IT som pedagogiskt verktyg i undervisningen, men då måste det användas på rätt sätt för att vara till nytta i undervisningen. Att arbeta på ett traditionellt sätt har sina fördelar. Därför bör i undervisningen varvas med IT som hjälpmedel och med papper och penna som det är i den traditionella undervisningen. Lärarna ansåg även att IT är bra utifrån demokrati perspektivet.

    Slutsatser: Generellt har lärarna på FG en positiv inställning till IT som pedagogiskt verktyg i undervisningen, i alla fall när det fungerar. Vilket det oftast gör tack vare IT-administratören. Lärarna anser att om IT används på rätt, så kan det vara individanpassad, stimulerande, motiverande, lärorikt, effektivt och en viktig informationskälla, t ex Internet. Det är också ett bra kommunikationsverktyg i skolan och i samhället i övrigt, men dess betydelse ska inte överskattas, eftersom lärarens pedagogiska förmåga och hur den övriga organsiationen ser ut är lika viktigt. Detta om IT ska kunna användas i undervisningen i skolan. Många av respondenterna tycker att IT är bra verktyg, som underlättar arbetet både för lärare och elever, även om det kan vara belastande ibland. I och med de vinster som kan uppnås med IT som pedagogiskt verktyg kan det vara värt att använda IT i undervisningen. Lärarna i undersökningen är noga med att eleverna ska granska källorna kritiskt, speciellt från Internet. Lärarna handleder eleverna att de själva ska lära sig, alltså det metakognitiva. Bland eleverna har killarna större förkunskaper inom IT än tjejerna och ser tekniken i sig och dess funktioner, medan tjejerna är mer interesserade av hur IT ska användas som ett pedagogiskt verktyg. Pojkarna spelar mer datorspel än flickorna och flickorna chattar mer än pojkarna.

  • 95.
    Thorin, Eva
    et al.
    Mälardalen University, Department of Public Technology.
    Brand, Heike
    University of Stuttgart, Germany.
    Weber, Christoph
    University of Stuttgart, Germany.
    Long-term Optimization of Cogeneration Systems in a Competitive Market Environment2005In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 81, no 2, p. 152-169Article in journal (Refereed)
    Abstract [en]

    A tool for long-term optimization of cogeneration systems is developed that is based on mixed integer linear programming and Lagrangian relaxation. We use a general approach without heuristics to solve the optimization problem of the unit commitment problem and load dispatch. The possibility to buy and sell electric power at a spot market is considered as well as the possibility to provide secondary reserve. The tool has been tested on a demonstration system based on an existing combined heat and power (CHP) system with extraction-condensing steam turbines, gas turbines, boilers for heat production and district heating networks. The key feature of the model for obtaining solutions within reasonable times is a suitable division of the whole optimization period into overlapping subperiods. Using Lagrangian relaxation the tool can be applied to large CHP systems. For the demonstration model almost optimal solutions were found.

  • 96.
    Thorin, Eva
    et al.
    Mälardalen University, Department of Public Technology.
    Manbo, Thomas
    Mälardalen University, Department of Public Technology.
    Jacobson, Henrik
    Mälardalen University, Department of Public Technology.
    Tommy, Törnqvist
    Mälardalen University, Department of Social Sciences.
    Examination med hjälp av dagbok- erfarenheter från en kurs tillhörande civilingenjörsutbildningen i samhällsteknik vid Mälardalens högskola2007Other (Other (popular science, discussion, etc.))
    Abstract [en]

    Ett intressant sätt att kombinera examination och inlärning är att examinera genom att studenterna under kursens gång får skriva dagbok och göra reflektioner över sin egen inlärning. Fördelen är också att det befrämjar kontinuerlig inlärning. Vi har provat denna examinationsform i en kurs tillhörande årskurs 4 inom vår civilingenjörsutbildning (civilingenjör i samhällsteknik). En stor del av kursen består av ett projektarbete och anledningen till att vi från början valde dagbok som examinationsform var att vi bedömde att vi därmed skulle få större möjligheter att göra en rättvis bedömning av studenternas individuella kunskaper. Kursen gick första gången under vårterminen 2006 och för andra gången vårtterminen 2007. Våra erfarenheter är övervägande positiva men det finns också nackdelar och svårigheter som t ex lärarinsats, studenters ovana vid formen och kriterier för betygssättning.

  • 97.
    Udd, Staffan
    et al.
    Mälardalen University, Department of Innovation, Design and Product Development.
    Carling, Linda
    Mälardalen University, Department of Innovation, Design and Product Development.
    Filppu, Ola
    Mälardalen University, Department of Innovation, Design and Product Development.
    Behzadnia, Shiva
    Department of Public Technology.
    Öhman, Hanna
    Mälardalen University, Department of Innovation, Design and Product Development.
    Stade, Christian
    Mälardalen University, Department of Innovation, Design and Product Development.
    Möten i stadsrummet: Fyra fallstudier om plats och rum i Eskilstuna2007Report (Other scientific)
  • 98. Vassilev, Nikolay
    et al.
    Requena, Antonina R.
    Nieto, Leopoldo M.
    Nikolaeva, Lana
    Mälardalen University, Department of Public Technology.
    Vassileva, Maria
    Production of manganese peroxidase by Phanerochaete chrisosporium grown on medium containing agro-wastes/rock phosphate and biocontrol properties of the final product2009In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 30, no 1, p. 28-32Article in journal (Refereed)
    Abstract [en]

    A mixture of dry olive wastes, sugar beet wastes, and rock phosphate was treated with Phanerochaete chrisosporium. Optimizing the solid-state fermentation parameters, the fungus was able to simultaneously produce 1100U/l manganese peroxidase and solubilize rock phosphate (26 mg/flask soluble P) after a 21-day process. The final fermentation product was found to significantly improve growth and N and P uptake of mycorrhized plants. Combined application of arbuscular mycorrhizal fungus and microbially treated agro-wastes and partially solubilized rock phosphate exerted biocontrol functions on Fusarium oxysporum inoculated in a typical Mediterranean soil. The described biotechnological scheme offers an environmentally safe alternative to chemical fungicide application. 

  • 99.
    Vienola, Sari
    Mälardalen University, Department of Public Technology.
    Lakningsförsök med furubarksflis: en utredning om utsläpp av fenolföreningar samt metallsorption2007Independent thesis Basic level (degree of Bachelor), 10 points / 15 hpStudent thesis
    Abstract [en]

    The filters used today to purify water are often expensive and the need to find new filter materials is substantial. Studies of pine bark have shown that this is a material that may be used as an alternative to conventional filter materials, such as activated carbon. However, the study of pine bark has shown that a leakage of phenolic compounds may occur when using the material for water purification. Therefore, the purpose of this report is to investigate the release of phenols from pine bark, in order to evaluate the use of pine bark as a filter material. Another assignment is to investigate the amount of metals adsorbed by the filter material. The studies were carried out through three leaching experiments. As leachates, double deionised water and storm water were used. The phenol concentration in the leachate was determined for both double deionised water and storm water. The degree of metal sorption was measured only for the storm water. The measured phenol concentration in the double deionised water was 4.40 mg/L and in the storm water 4.81 mg/L. These concentrations exceed the Canadian guideline value, of 4.0 μg/L, more than a 1000 times. No metal sorption occurred as the metal content of the storm water was too low. Instead a release of metals from the pine bark into the eluate of the storm water occurred. The leaching attempts also resulted in a decline of the pH-values of the two different waters. The pH-values for the double deionised water and the storm water decreased from 7.0 to 4.3 and from 6.0 to 4.2 respectively. A release of phenols was ascertained with a significant difference in concentrations between double deionised water and storm water. Therefore it is not advisable to use pine bark filters for purification of water with low concentrations of metals, as the filter material may release metals into the water under such conditions.

    Keywords: pine bark, phenol, filter materials, leaching, metal sorption, toxicity

    Nyckelord: furubarksflis, fenol, filtermaterial, lakning, metallsorption, toxicitet

  • 100.
    Waara, Sylvia
    et al.
    Mälardalen University, Department of Public Technology. Mälardalen University, School of Sustainable Development of Society and Technology.
    Waara, Karl-Otto
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Forsberg, Åke
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Fridolfsson, Magnus
    Performance of a constructed wetland system for treatment of landfill leachate.2008In: Waste 2008. Waste and Resource management-A shared responsibility, 2008, p. 655-667Conference paper (Refereed)
    Abstract [en]

    The performance of a constructed wetland for treatment of landfill leachate has been evaluated based upon data obtained during 4 years (2003-2006). It consists of a series of 10 ponds with a total capacity of 52.000 m3 covering 8 ha. Using univariate and multivariate statistics (PCA) the reduction pattern of a large number of chemical parameters including heavy metals has been investigated in 3 parts of the wetland with equal volume. Analyses show that many parameters are removed to the greatest extent in the first part of the system (e.g. many heavy metals, total suspended solids) or the second part of the system (N-NH4) while other parameters such as total nitrogen are more gradually reduced (10 ton/year removed).  Toxicity testing with 5 bioassays showed that toxicity was sometimes observed at the inlet but no toxicity was observed at the outlet for 4 of the test species. The data presented will be used for optimizing the treatment process as well as to improve the monitoring program.

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