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  • 1.
    Abbas, Asad
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap.
    Flow sheeting software as a tool when teaching Chemical Engineering2011Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The aim of this thesis is to design different chemical processes by using flow sheeting software and to show the usefulness of flow sheeting software as an educational tool. The industries studied are hydrogen, sulfur, nitric acid and ethylene glycol production and a model of drying technique is also included. Firstly, there is an introduction of chemcad as a tool when teaching chemical processes and explanation of each industry which is selected to design. Various production methods for each product are explained and the advantages of the method which is selected to design the chemical flow sheet are discussed. There is also an introduction of the industrial uses of these products formed in Pakistan. The models are designed by using different reactors, heat exchangers, pumps, mixers, boilers and distillation column. The models are designed based upon data taken from literature. The temperature and pressure values are in good agreement with data mentioned in literature. The material balance shown by Chemcad is quite different from data mentioned in literature. Some changes in thermodynamic properties of components in Chemcad software might lead to better agreement between the Chemcad models and literature data. It is not possible to use catalyst in Chemcad to increase the rate of reaction. One possibility is to introduce new components. It is good to use equilibrium reactor when it is required to convert the given component into respective products provided that either conversion of the equilibrium constant are known. It is difficult to study the hidden critical assumptions built in the model when using Gibb’s reactor, as a result there is a deviation in behavior from the system described in the literature. Gibb’s reactor is useful when neither conversion ratio nor equilibrium constant is known.

    Fulltekst (pdf)
    Flow sheeting software
  • 2.
    Abbas, Azhar
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap.
    GPIB- kommunikation och PID reglering med LabVIEW2009Independent thesis Basic level (university diploma), 15 poäng / 22,5 hpOppgave
    Abstract [sv]

    LabVIEW ger en snabb och enkel tillgång till att styra instrument och en mycket stor databas med drivrutiner för DAQ-kort och olika datorgränssnitt (GPIB, serie, osv.).

    Många instrument och datorer kan anslutas till GPIB-bussen.  Detta kan ge en praktisk modell för utveckling av instrumentets styrprogram i LabVIEW med hjälp av GPIB-gränssnittet.

    Ett program i LabVIEW 8.2 med hjälp av GPIB-bussen kan kopplas till t.ex. multimetern (HP-34401A) för att mäta och visa multimeters noggrannhet. Men på grund av fel i drivrutiner för GPIB-gränssnittet kunde jag inte köra programmet med GPIB-bussen.

    Genom att använda LabVIEW 8.2 med hjälp av DAQ-kort kan en PID-regleringsalgoritm simuleras. PID konstrueras med virtuella instrument som innehåller alla nödvändiga komponenter och utrustning som krävs för att reglera någon linjär eller olinjär process exempelvis att nivåreglera två tankar i serie. Här stöter vi på alla de grundläggande regulatorer och får möjlighet att bygga PID med LabVIEW på ett enkelt sätt. Det finns två metoder för att bygga PID. Den första är med matematiska funktioner och den andra är med ’’Simulations functions control’’. Arbetet visar att bägge metoderna fungerar bra för att lösa uppgiften jämfört med färdiga PID-controls på LabVIEW.

    Fulltekst (pdf)
    fulltext
    Download (pdf)
    SUMMARY01
  • 3. Abdel-Rehim, M.
    et al.
    Altun, Zeki
    Blomberg, Lars G
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemi och biomedicinsk vetenskap.
    New trend in sample preparation: On-line microextraction in packed syringe (MEPS) for LC and GC applications, Part II, Determination of ropivacaine and its metabolites in human plasma samples using MEPS-LC-MS-MS2004Inngår i: J. Mass Spectr., 39 (2004) 1488-1493Artikkel i tidsskrift (Fagfellevurdert)
  • 4. Abdel-Rehim, M.
    et al.
    Carlsson, Gunilla
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Paper Surface Centre. Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemi och biomedicinsk vetenskap. Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap.
    Bielenstein, M.
    Arvidsson, T.
    Blomberg, Lars G
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemi och biomedicinsk vetenskap.
    Evaluation of Solid-Phase microextraction (SPME) for Study of the protein Binding in Human Plasma Samples,2000Inngår i: J. Chromatogr. Sci., 38 (2000) 458-464Artikkel i tidsskrift (Fagfellevurdert)
  • 5. Abdel-Rehim, M.
    et al.
    Hassan, Z.
    Blomberg, Lars G
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemi och biomedicinsk vetenskap.
    Hassan, M.
    Determination of Busulphan in plasma samples by gas chromatography-mass spectrometry (GC-MS) using on-line derivatization utilizing solid-phase microextraction (SPME)2003Inngår i: J. Therapeutic Drug Monitoring, 25 (2003) 400-406Artikkel i tidsskrift (Fagfellevurdert)
  • 6. Abdel-Rehim, M.
    et al.
    Skansen, P.
    Vita, M.
    Hassan, Z.
    Blomberg, Lars G
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemi och biomedicinsk vetenskap.
    Hassan, M.
    Microextraction in packed syringe / liquid chromatography /electrospray tandem mass spectrometry (MEPS/LC/MS/MS) for quantification of olomoucine in human plasma samples2005Inngår i: Anal.Chim. Acta., 539 (2005) 35-39Artikkel i tidsskrift (Fagfellevurdert)
  • 7.
    Abdel-Rehim, Mohamed
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemi och biomedicinsk vetenskap. AstraZeneca R&D Sodertalje, Global DMPK, SE-15185 Sodertalje, Sweden.;Stockholm Univ, Dept Analyt Chem, SE-10691 Stockholm, Sweden.;Karlstad Univ, Dept Chem & Biomed Sci, Fac Sci & Technol, SE-65188 Karlstad, Sweden..
    Microextraction by packed sorbent (MEPS): A tutorial2011Inngår i: Analytica Chimica Acta, ISSN 0003-2670, E-ISSN 1873-4324, Vol. 701, nr 2, s. 119-128Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This tutorial provides an overview on a new technique for sample preparation, microextraction by packed sorbent (MEPS). Not only the automation process by MEPS is the advantage but also the much smaller volumes of the samples, solvents and dead volumes in the system. Other significant advantages such as the speed and the simplicity of the sample preparation process are provided. In this tutorial the main concepts of MEPS will be elucidated. Different practical aspects in MEPS are addressed. The factors affecting MEPS performance will be discussed. The application of MEPS in clinical and pre-clinical studies for quantification of drugs and metabolites in blood, plasma and urine will be provided. A comparison between MEPS and other extraction techniques such as SPE, LLE, SPME and SBSE will be discussed. (C) 2011 Elsevier B.V. All rights reserved.

  • 8.
    Abdel-Rehim, Mohamed
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemi och biomedicinsk vetenskap. AstraZeneca R&D Sodertalje, Global DMPK, Sodertalje, Sweden.;Karlstad Univ, Fac Sci & Technol, Dept Chem & Biomed Sci, Karlstad, Sweden..
    On-Line Whole Blood Analysis Using Microextraction by Packed Sorbent and LC-MS-MS2011Inngår i: LC GC North America, ISSN 1527-5949, E-ISSN 1939-1889, Vol. 29, nr 7, s. 612-618Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Microextraction by packed sorbent (MEPS) is a new technique for sample preparation that can be connected on-line with liquid chromatography (LC) or gas chromatography (GC) systems without any modifications. This article describes the use of MEPS in clinical and preclinical studies to quantify different drugs in whole blood samples. MEPS was used to determine cyclophosphamide in mouse blood from preclinical g studies using 20 mu L of blood samples. The interday accuracies and 0 precisions ranged from 107-109% and from 2.0-7.0%, respectively. The determination of four immunosuppressive drugs in human blood by MEPS and liquid chromatography-mass spectrometry (LC-MS) is described. The method showed a good selectivity and sensitivity. The calibration curves for everolimus, sirolimus, and tacrolimus ranged from 0.5 to 50 ng/mL and for cyclosporine from 3.0 to 1500 ng/mL. Intraday precisions for the studied immunosuppressive drugs were 2.0-11.7% and interday precision ranged from 5.1 to 13.7% (CV).

  • 9.
    Abdel-Rehim, Mohamed
    et al.
    AstraZeneca R&D Södertälje, Södertälje, Sweden.
    Andersson, L.I.
    AstraZeneca R&D Södertälje, Södertälje, Sweden.
    Altun, Zeki
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemi och biomedicinsk vetenskap.
    Blomberg, Lars G
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemi och biomedicinsk vetenskap.
    Microextraction in Packed Syringe Online with Liquid Chromatography-Tandem Mass Spectrometry: Molecularly imprinted polymer as packing material for MEPS in selective extraction of ropivacaine from plasma2006Inngår i: Journal of Liquid Chromatography & Related Technologies, ISSN 1082-6076, E-ISSN 1520-572X, Vol. 29, nr 12, s. 1725-1736Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The excellent performance of a new sample preparation method, microextraction in packed syringe (MEPS), was recently illustrated by online LC‐MS and GS‐MS assays of local anaesthetics in plasma samples. In the method, approximately 1 mg of solid packing material was inserted into a syringe (100–250 µL) as a plug. Sample preparation took place on the packed bed. The new method was easy to use, fully automated, of low cost, and rapid in comparison with previously used methods. This paper presents the use of molecularly imprinted polymers (MIPs) as packing material for higher extraction selectivity. Development and validation of a method for MIP‐MEPS online with LC‐MS‐MS using ropivacaine in plasma as model compound were investigated. A bupivacaine imprinted polymer was used. The method was validated and the standard curves were evaluated by means of quadratic regression and weighted by inverse of the concentration: 1/x for the calibration range 2–2000 nM. The applied polymer could be used more than 100 times before the syringe was discarded. The extraction recovery was 60%. The results showed high correlation coefficients (R 2 >0.999) for all runs. The accuracy, given as a percentage deviation from the nominal concentration values, ranged from -6% to 3%. The precision, given as the relative standard deviation, at three different concentrations (QC samples) was consistently about 3% to 10%. The limit of quantification was 2 nM.

  • 10. Abdel-Rehim, Mohamed
    et al.
    Dahlgren, Marie
    Blomberg, Lars G
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemi och biomedicinsk vetenskap.
    Quantification of ropivacaine and its major metabolites in human urine samples utilizing microextraction in packed syringe automated with liquid chromatography-tandem mass spectrometry (MEPS-LC-MS-MS)2006Inngår i: J. Sep. Sci., 29 (2006) 1658-1661Artikkel i tidsskrift (Fagfellevurdert)
  • 11. Abdel-Rehim, Mohamed
    et al.
    Dahlgren, Marie
    Claude, Saturnin
    Tabacchi, Raphael
    Blomberg, Lars G
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemi och biomedicinsk vetenskap.
    Microextraction in packed syringe (MEPS) utilizing methylcyanopropyl silarylene as coating polymer for extraction of drugs in biological samples,2006Inngår i: J. Liq. Chromatogr. & Relat. Technol., 29 (2006) No. 17, 2537-2544Artikkel i tidsskrift (Fagfellevurdert)
  • 12.
    Abdulhadi, Sami
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap.
    ARM i inbyggt system: med prototyp2009Independent thesis Basic level (degree of Bachelor), 15 poäng / 22,5 hpOppgave
    Abstract [sv]

    Inbyggda system blir allt vanligare i dagens samhälle. De inbyggda systemen finns i nästan allt nuförtiden, från diverse fordon till leksaker för barn.

    Dagens teknik innebär bland annat att gårdagens lösningar kan realiseras på en bråkdel av den tidigare ytan. Allt mer blir ytmonterat med mindre och mer komplexa kretsar. Detta är inte alltid till utvecklarnas fördel då montering av prototypkort blir en svår och/eller dyr process.

    Målet är att ta fram ett inbyggt system med en ARM-processor. Systemet ska innehålla USB-OTG, ethernet, minne av olika slag som FRAM och microSD samt en display med pekskärm för användargränssnitt. Projektet omfattar allt från komponentval till test och verifiering med programkod.

    Tiden räckte inte till för att få med alla delar som planerats. Resultatet av projektet blev ett prototypkort och två små programsekvenser, en som blinkar två lysdioder på kortet och en som skriver ut en bild på displayen.

    Detta inbyggda system är i första hand till för utvärdering av ARM-processorer för Mikrodidakt AB.

    Fulltekst (pdf)
    ARM i inbyggt system - med prototyp
  • 13.
    Aboul-Enein, Mohamed N.
    et al.
    Natl Res Ctr, Pharmaceut & Drug Ind Res Div, Med & Pharmaceut Chem Dept, Med Chem Grp, Giza 12622, Egypt..
    El-Azzouny, Aida A.
    Natl Res Ctr, Pharmaceut & Drug Ind Res Div, Med & Pharmaceut Chem Dept, Med Chem Grp, Giza 12622, Egypt..
    Attia, Mohamed I.
    Natl Res Ctr, Pharmaceut & Drug Ind Res Div, Med & Pharmaceut Chem Dept, Med Chem Grp, Giza 12622, Egypt.;King Saud Univ, Coll Pharm, Dept Pharmaceut Chem, Riyadh 11451, Saudi Arabia..
    Maklad, Yousreya A.
    Natl Res Ctr, Pharmaceut & Drug Ind Res Div, Med & Pharmaceut Chem Dept, Pharmacol Grp, Giza 12622, Egypt..
    Amin, Kamilia M.
    Cairo Univ, Fac Pharm, Dept Pharmaceut Chem, Cairo, Egypt..
    Abdel-Rehim, Mohamed
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemi och biomedicinsk vetenskap.
    El-Behairy, Mohammed F.
    Natl Res Ctr, Pharmaceut & Drug Ind Res Div, Med & Pharmaceut Chem Dept, Med Chem Grp, Giza 12622, Egypt..
    Design and synthesis of novel stiripentol analogues as potential anticonvulsants2012Inngår i: European Journal of Medicinal Chemistry, ISSN 0223-5234, E-ISSN 1768-3254, Vol. 47, s. 360-369Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A series of stiripentol (SIP) analogues namely, 2-1(1E)-1-(1,3-benzodioxol-5-yl)-4,4-dimethylpent-1-en-3-ylidene]-N-(aryl/H)hydrazinecarboxamides 7a-h, (+/-)-(5RS)-N-(aryl/H)-(1,3-benzodioxol-5-yl)-3-tert-butyl-4,5-dihydro-1H-pyrazole-1-carboxamides (+/-)-8a-h, and (+/-)-[(5RS)-(1,3-benzodioxol-5-yl)-3-tert-butyl-4,5-dihydro-1H-pyrazol-1-yl](aryl)methanones (+/-)-13a-f was synthesized by adopting appropriate synthetic routes and was pharmacologically evaluated in the preliminary anticonvulsant screens. The selected bioactive new chemical entities were subjected to ED50 determination and neurotoxicity evaluation. The most active congeners are 7h in MES screen and (+/-)-13b in scPTZ screen which displayed ED50 values of 87 and 110 mg/kg, respectively, as compared to that of STP (ED50 = 277.7 and 115 mg/kg in MES and scPTZ, respectively). (C) 2011 Elsevier Masson SAS. All rights reserved.

  • 14. Acedo, L.
    et al.
    Santos, A.
    Bobylev, Alexander
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för matematik.
    On the derivation of a high-velocity tail from the Boltzmann-Fokker-Planck equation for shear flow2002Inngår i: J. Statist. Phys, Vol. 109:5-6Artikkel i tidsskrift (Fagfellevurdert)
  • 15.
    Adolfsson, Oscar
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap.
    Blomqvist, Marcus
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap.
    Vägghängd duschpall: Utveckling av duschpall för Etac Supply Center AB2010Independent thesis Basic level (university diploma), 15 poäng / 22,5 hpOppgave
    Abstract [en]

    This degree project has been carried out by Oscar Adolfsson and Marcus Blomqvist, during the spring of 2010, both studying to become Bachelor of Science in Innovation and Design Engineering, at Karlstad University. The degree project includes 22,5 credits.The work is done on behalf of Etac Supply Center AB in Anderstorp. Etac is a company developing and manufacturing home health care products, with operation in Sweden, Norway, Denmark, England and Germany, and with sales worldwide. Bo Lindqvist, R & D manager has been the contact person at Etac.During the project the students has had a workplace at Semcon Caran AB in Karlstad. Semcon has also been helpful as a sounding board.The objective of the work has been developing a new, wall mounted shower chair, assigned for persons with difficulty to stand up while showering.Etacs requirement of the shower chair is that it should be able to support a user with a weight of 100 kg, the chair shouldn’t have any outrigger, optional should be armrests and backrest. The seat should be mountable in existing bathrooms, and act as a complement for the current shower seats sold by Etac. It’s very important that the result is good looking, and appealing to new target groups.In the start of this project, the students have been carrying through a benchmarking, mainly at the NordBygg fair in Stockholm. The students have been agreeing about the lack of products with both functionality and aesthetic appealing qualities.The result is adjusted to fit the most common wall constructions in Sweden.Four concepts have been developed, and among these four, one is the final result. The final result consists of two aluminium wall rails and a plastic seat. A plastic backrest, and armrest in both plastic and stainless steel are optional.During the work, the specifications on products like these, from the Swedish institute of assistive technology, concerning strength and risks of pinching has been observed.The project has resulted in CAD-files and a model in scale 1:3, manufactured by Etac.

    Fulltekst (pdf)
    FULLTEXT01
  • 16.
    Aeyadi, Amin
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik.
    Formation of protective lubricious oxide layers on the surface of nitrogen alloyed steels in self-mated sliding2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Fulltekst (pdf)
    fulltext
  • 17.
    Ahl, Daniel
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för energi-, miljö- och byggteknik.
    Analysis of how different mesh functions influence the result in CFD-simulation of a marine propeller:  2013Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Fulltekst (pdf)
    fulltext
  • 18.
    Ahlgren, Joakim
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap.
    Lidström, Joakim
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap.
    Gastromax Duo: Ett kompakt rivjärn för den moderna hemmakocken2010Independent thesis Basic level (university diploma), 15 poäng / 22,5 hpOppgave
    Abstract [sv]

    ”Gastromax Duo” är ett examensarbete som genomförts inom ramarna för Innovations- och designingenjörsutbildningen vid Karlstads universitet. Projektet har självständigt fullföljts av Joakim Ahlgren och Joakim Lidström under vårterminen 2010. Examensarbetets omfattning är 22,5 hp.

    Uppdragsgivare för projektet är Peter Ottosson och Jonas Eriksson på Sveico AB i Gnosjö. Handledare för projektet hos uppdragsgivaren har varit Peter Johansson. Monica Jakobsson har varit handledare på Karlstads universitet. Lennart Wihk, industridesigner och universitetsadjunkt vid Karlstads universitet, är examinator och har fungerat som handledare och bollplank i designprocessen.

    Sveico AB ligger i Gnosjö och tillverkar köksredskap och andra tillbehör till köksmiljön. I Sveicos produktportfölj återfinns produktserien Gastromax, som riktar sig specifikt till hemmakocken. Gastromax-serien saknar emellertid ett kompakt sönderdelningsredskap för matvaror, vilket föranledde detta produktutvecklingsprojekt.

    Den största enskilda delen i projektet har varit en grundlig förstudie där projektgruppen kartlagt vilka behov och önskemål som finns hos användarna, samt hur marknaden ser ut för produkten. Förstudien består av intervjuer med konsumenter, professionella användare och representanter för handeln samt användarstudier.

    Under produktutvecklingsprocessen har en rad olika idégenereringsmetoder används, såväl internt i projektgruppen, som externt med utomstående individer. Under den påföljande konceptutvecklingsfasen lades stor vikt vid framtagningen av fysiska modeller för utvärdering av idéer och lösningar.

    Av de nitton koncept som sammanställdes från idégenereringsfasen, sållades sex koncept ut med hjälp av systematiska utvärderingsmetoder. De sex koncepten presenterades för uppdragsgivaren, som i sin tur valde ut två av koncepten, vilka projektgruppen vidareutvecklat till det slutgiltiga produktförslaget.

    Den slutgiltiga detaljlösningen omhuldas av sekretess, men tre nyckelegenskaper hos det hopfällbara sönderdelningsredskapet kan noteras:

    • Lång rivyta
    • Ställbar arbetsvinkel
    • Två rivytor, en fin och en grov

    Projektets slutliga resultat är en produktbeskrivning med förslag på övergripande utformning, mekanisk lösning av ställbarheten och materialval för produktens olika delar.

    Fulltekst (pdf)
    FULLTEXT01
  • 19.
    Ahmed, Faisal Mahmood
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för fysik och elektroteknik.
    Estimated Droop Control for Parallel Connected Voltage Source Inverters: Stability Enhancement2013Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Abstract [en]

    Renewable Energy Sources (RES) are considered as the replacement of conventionalenergy sources. These RES can use wind energy, solar light, bio waste and can alsobe in the form of small hydro power units. These RES has very poor power qualityand contains voltage uctuations and variable frequency. These factors make RES astability risk for the main utility grid. As a solution, currently inverters with dierentdesign techniques are being used as an interface between RES and main utility grid. Thecurrent study proposed a new technique "estimated droop control" for inverter design.The conventional droop control technique which was already used in inverter design, hasdiculty in synchronizing parallel connected inverters with dierent droop gains and lineimpedances. The proposed "estimated droop control" does not use any predened droopvalues for inverters and all inverters are responsible for the estimation of their own droopvalues with respect to their output power. Therefore, inverters are not bound to usesame and static droop values which are considered as a vital communication link. Theproposed design methodology has made inverters independent from this only virtual linkof communication due to which the reliability of a system has increased. The proposeddesign technique has given very good results in a simulation run. When the Simulinkmodel was run in parallel connected inverter with dierent line impedances, it was asuccess as both inverters started operating with same droop values as they were sharingan equal load. The most important test was with dierent line impedances because inconventional droop control it is dicult for inverters to keep their synchronism withdierent line impedances and an unequal load sharing make inverters to deviate fromtheir nominal values and to generate dierent tracking signals for each set. This problemhas been successfully solved with estimated droop control as in this method each inverterset its droop gains according to its output power, which helps an inverter to operate atnominal values with dierent droop gains and line impedance.

    Fulltekst (pdf)
    Faisal
    Fulltekst (pdf)
    Arkivfil
  • 20.
    Ahmed Ismail, Mostafa
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik.
    Modified lignin as replacement of carbon black in elastomers- For the development of sustainable tyre technology: The substitution of carbon black with modified lignin- Green tyre technology2020Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Due to its large flexibility, low-price, large availability, and properties lignin is seen as an important compound with a wide range of applications. The increasing demand of fossil-based rubber materials is causing a serious threat to the environment and it is contributing to plastic- and marine pollution, ozone depletion and carbon dioxide emission (CO2) [1,2]. Numerous toxicological researches highlight that Carbon black may act as a universal carrier of wide variety of chemicals of varying toxicity to the human body [3,4]. Consequently, researcher endeavours in finding sustainable and eco-friendlier alternatives. The aim of this thesis was to further investigate the possibilities of replacing carbon black with modified lignin in rubber elastomeric materials- for the development of sustainable tyre technology. The research questions for this thesis were divided in four parts:

     

    • How does lignin (unmodified and modified) structure affect the mechanical properties of the rubber compound?
    • How does lignin affect the cross-link and vulcanisation of the rubber compound?
    • How does lignin affect the dispersion of the rubber compound?
    • Which modification of lignin is more compatible with the rubber compound?

    Lignin is the second most abundant biopolymer on earth (after cellulose) and is mainly extracted from black liquor, which is obtained as a by-product from the pulp- and paper. In this study, pure lignin was obtained from Lignoboost process (Lignocity) and underwent an esterification process of aldehydes (1. Protonic, 2. Butyric, 3. Isobutyric 4. Methacrylic and 5. Crotonic). LignoCity 2.0 is a project focusing on the development of sustainable products and processes connected to lignin. The structure of the modified lignin was characterized using a FTIR-spectra. Furthermore, seven different rubber compounds were produced at Anva Poly Tech, which is a company that manufactures rubber materials in Sunne, Sweden. The mechanical testing involved: Tensile strength, IRHD, Hardness, Rebound Resilience and Rheometer curve. It was observable that the addition of lignin in rubber compounds did not significantly improve the mechanical properties compared to conventional carbon black. However, the rheometer curves of the lignin samples clearly indicate an increase in scorch time and that lignin takes part in the vulcanization process, thus the delay in crosslinking phase.

     In addition, it was visible that the fully replacement of carbon black with lignin (unmodified and modified) increased the elongation at break. Furthermore, the FTIR spectra indicated a complete and successful modification of lignin. In addition, compared to unmodified lignin, it was visible that the modified lignin significantly improved the mechanical properties. Therefore, it was possible to conclude that the configuration and double bonds of the aldehydes had an impact on the vulcanization process. Butyric and isobutyric lignin were the better choices compared to the other lignin samples.

    Fulltekst (pdf)
    fulltext
    Fulltekst (pdf)
    Arkivfil
  • 21.
    Ahmed, Naeem
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för fysik och elektroteknik.
    Cooperative Spectrum Sensing for Cognitive Radio Networks2012Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The great developments in the field of wireless communications that has been accelerated by the commercial need for better services has led to the application of wireless systems in many fields of life. The effect of wireless technology is much widened, like for safety applications, home automation, smart grid control, medical wearable, embedded wireless devices, entertainment systems etc.

    Direct and indirect surveillance of spectrum treatment has acknowledged the sequential and spatial accessibility of spectrum inside allocated frequency bands. This implies that spectrum deficiency is becoming a main problem. Therefore, spectrum deficiency problem arises here in terms of that most of the licensed primary users are not using their spectrum due to any reason of either geographical variation or temporal basis, and lot of allotted spectrum is unused and under-utilized. Moreover, along with spectrum deficiency problem, other issues are also linked like interference caused by secondary unlicensed users to primary licensed users while sharing the work load among each others, and problem of vacating the spectrum band in less fewer time frames after primary users detection.

    Cognitive networks assure to tackle these spectrum deficiency and other associated problems by accommodating secondary (unlicensed) users, in the spectrum region which is under-utilized. Spectrum Sensing is the prime motivation for cognitive radio and ensures that secondary (unlicensed) users do not propose unbearable levels of interference to primary (licensed) users.

    Cooperative Spectrum Sensing methodologies are still an open window of research. This work is related to cope up the problem of spectrum deficiency and associated problems, by developing an approach for establishment of grouping/clustering between secondary users in a cooperative spectral environment. This approach ensures that members within a group are highly correlated. As a result, the workload on each sensing node within a group is reduced. The effectiveness of this approach depends upon the accuracy of fused decision related to the presence or absence of primary (licensed) user at a particular band (50MHZ to 100MHZ). This approach also depends on the factor that time taken in sensing the primary (licensed) users should be less enough so that decision in vacating the band by the Cognitive Radio secondary users could be taken in fewer time frames. This latter metric is known to be ‘agility’, which eventually comes with the outcome of minimum interference to primary users via their early recognition.

  • 22.
    Ahmed, Umair
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för fysik och elektroteknik.
    Racing Driver Model in Dymola Vehicle Dynamics Library (VDL): Steering Controller Design2012Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Abstract [en]

    Racing drivers always want to traverse path at vehicle’s maximum performance limits while keeping the vehicle at its ideal trajectory. The main objective of this report is to elaborate strategy for the path following problem in which driver has to follow the predefined 2D roads. New steering controller design for closed loop racing driver model in Dymola vehicle dynamics library is developed. The methodology proposed by Sharp et al. [2] is followed with the optimal velocity profile that tries to mimic the actions of the real drivers in real time scenarios. Vehicle handling limits i.e. longitudinal and lateral limits are defined before simulation. While travelling in the neighbourhood of optimal velocity on the straight road as well as during the curves, the performance of the steering controller is tested by conducting the test on J turn, Clothoid, Extended chicane and the closing curve path and also tested during the different environment effects e.g. when there is a side wind affecting the vehicle. Performance of existing and new steering controllers discussed and compared in result chapter. It is ensured that the drawbacks in the existing steering controller are eliminated by using the proposed methodology in new implemented steering controller.

    Key Words: Driver Model, Steering Controller, Path following, Velocity profile

    Fulltekst (pdf)
    fulltext
  • 23. Aldaeus, Fredrik
    et al.
    Johansson, Lars-Erik
    Jönsson, Mats
    Jonsson, Gunnar
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för fysik och elektroteknik.
    Lindberg, Ulf
    Roeraade, Johan
    Hamp, Sven
    Escherichia Coli Behavior in an Open Dielectrophoretic Microsystem2004Konferansepaper (Annet (populærvitenskap, debatt, mm))
  • 24. Aldaeus, Fredrik
    et al.
    Yuan, Lin
    Jönsson, Mats
    Johansson, Lars-Erik
    Jonsson, Gunnar
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för fysik och elektroteknik.
    Roeraade, Johan
    Amberg, Gustav
    Dielectrophoresis of Living Cells - New Concepts and Challenges2005Konferansepaper (Annet (populærvitenskap, debatt, mm))
  • 25.
    Aldaz, J. M.
    et al.
    Univ Autonoma Madrid, ICMAT, E-28049 Madrid, Spain.;Univ Autonoma Madrid, Dept Matemat, E-28049 Madrid, Spain..
    Barza, Sorina
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för matematik.
    Fujii, M.
    Osaka Kyoiku Univ, Dept Math, Kashiwara, Osaka 5828582, Japan..
    Moslehian, Mohammad Sal
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Advances in Operator Cauchy-Schwarz Inequalities and their Reverses2015Inngår i: Annals of Functional Analysis, E-ISSN 2008-8752, Vol. 6, nr 3, s. 275-295Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Cauchy-Schwarz (C-S) inequality is one of the most famous inequalities in mathematics. In this survey article, we first give a brief history of the inequality. Afterward, we present the C-S inequality for inner product spaces. Focusing on operator inequalities, we then review some significant recent developments of the C-S inequality and its reverses for Hilbert space operators and elements of Hilbert C*-modules. In particular, we pay special attention to an operator Wielandt inequality.

  • 26.
    Alfalah, Ranim
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för energi-, miljö- och byggteknik.
    Ammouri, Zainab
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för energi-, miljö- och byggteknik.
    Ekonomisk lönsamhet för solceller installerade på tak och fasad för flervåningsbyggnader2023Independent thesis Basic level (university diploma), 15 poäng / 22,5 hpOppgave
    Abstract [sv]

    Detta projekt syftar till att utvärdera olika kombinationer av solceller på tak och fasader för flervåningsbyggnader för att identifiera de mest kostnadseffektiva alternativen. Målet är att jämföra ekonomisk lönsamhet för solceller installerade på tak och fasader för två hyresfastigheter med olika uppvärmningssystem. En byggnad består av sju våningar och den andra har fyra våningar. Studiens ämne baseras på begränsade takytor i förhållande till golvyta och elbehov, och kombinerade solcellsinstallationer på tak, fasader och andra byggnads delar kan bidra till en effektiv lösning.

    Studiens beräkningar genomförs i VIP- Energy-programmet för att bestämma elbehov, den producerade solelen, egenanvänd solel, såld el och köpt el. Denna information används för att göra en livscykelkostnadsanalys i Excel, där olika installationer och kombinationer av solceller jämförs för varje fastighet under en 25-årsperiod. Analysen genomförs med två uppvärmningssystem fjärrvärme och bergvärmepump.

    Genom att kombinera VIP-Energy-programmet för att få energirelaterade data och LCC-verktyget för att analysera livscykelkostnaderna, kan göras en omfattande bedömning av solcellernas ekonomiska fördelar och lönsamhet för varje fastighet över en 25-årsperiod. Detta ger värdefull insikt för att fatta välgrundade beslut om installation och användning av solceller, samtidigt som det tar hänsyn till olika uppvärmningssystem och deras inverkan på investeringens återbetalningstid.

    Resultaten visar att kombinationen av solceller på tak och fasader ger den mest kostnadseffektiva lösningen för båda byggnaderna, oavsett vilket uppvärmningssystem som används. Dock varierar lönsamheten mellan de två uppvärmningssystemen, där bergvärmepumpsystemet visar sig vara mest fördelaktigt. Det beror på att det genererar högre besparingar och en kortare återbetalningstid. Resultaten visar att bergvärmepumpsystemet har en maximal återbetalningstid på 8 år i hus 4 och 7 år i hus 5, medan fjärrvärmesystemet har en maximal återbetalningstid på 14 år i hus 4 och 11 år i hus 5. Det innebär att investeringen återbetalas snabbare i bergvärmepumpsystemet jämfört med fjärrvärmesystemet.

    Byggnaden med sju våningar har en fördel då den har större ytor för fasadinstallationer, vilket ökar dess potential att producera el genom fasaden jämfört med den fyravåningsbyggnad som också studerades. 

    Nästan alla kombinationer av solceller i både byggnaderna visar rimliga återbetalningstider i förhållande till solcellernas garantitid på 12 år, och investeringen i solceller visar sig vara lönsam med stor potential för framtida vinster.

    Fulltekst (pdf)
    fulltext
  • 27.
    Alfredsson, Lottie
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap.
    Christenson, Sara
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap.
    Supplier Selection & Quality Expectations: Development of a Simple Supplier Evaluation Tool in a Norwegian Ventilation Systems Company2014Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    In today’s competitive market, survival and response to customer needs and

    expectations are enabled through high-quality products for low costs – quality

    products provided by suppliers fulfilling today’s quality-requirements for a low

    price. Companies have until recent years selected suppliers only according to a

    pricing structure, leaving other criteria’s, such as quality, behind.

    The purpose of this master thesis is therefore to investigate quality aspects that

    must be considered from a supplier evaluation perspective and design a simple

    evaluation tool for first-time supplier selections. Both new and existing

    suppliers will be tested with the tool according to information given during a

    case study made at Flexit AS, a Norwegian ventilation-systems company

    looking to introduce a structured approach for selecting suppliers.

    Through an extensive literature- and empirical study, where a survey, of which

    evaluation criteria’s to be included in the evaluation tool, was conducted

    together with several both semi-structured and unstructured interviews, a

    foundation for the design of the tool was presented.

    Quality management systems and quality performance measurements, such as

    rejection rate and delivery precision, are considered as fundamental aspects to

    consider when assessing a supplier. Acceptance levels of approval are set

    according to in-house objectives. If any evaluation tool including quality

    should be usable, an in-house quality system must therefore first be

    implemented by the in-house company – a notable improvement

    recommended to the case company.

    The design of the tool given from the thesis provides the evaluator with an

    opportunity to visualize and compare existing suppliers according to five

    criteria’s including cost, together with an additional spreadsheet for evaluation

    of new suppliers put forward as a foundation and an indicator if new suppliers

    are considering quality on a basic level.

    Fulltekst (pdf)
    Supplier Selection & Quality Expectations
  • 28.
    Alfredsson, Patrik
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap.
    Haeffner, Fredric
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap.
    Åtgärdsförslag för erosionsskador i Kölaälv2006Independent thesis Basic level (professional degree), 15 poäng / 22,5 hpOppgave
    Fulltekst (pdf)
    FULLTEXT01
  • 29.
    Algervik, Robert
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för matematik.
    Embedding Theorems for Mixed Norm Spaces and Applications2010Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    This thesis is devoted to the study of mixed norm spaces that arise in connection with embeddings of Sobolev and Besov type spaces. We study different structural, integrability, and smoothness properties of functions satisfying certain mixed norm conditions. Conditions of this type are determined by the behaviour of linear sections of functions. The work in this direction originates in a paper due to Gagliardo (1958), and was further developed by Fournier (1988), by Blei and Fournier (1989), and by Kolyada (2005).

    Here we continue these studies. We obtain some refinements of known embeddings for certain mixed norm spaces introduced by Gagliardo, and we study general properties of these spaces. In connection with these results, we consider a scale of intermediate mixed norm spaces, and prove intrinsic embeddings in this scale.

    We also consider more general, fully anisotropic, mixed norm spaces. Our main theorem states an embedding of these spaces to Lorentz spaces. Applying this result, we obtain sharp embedding theorems for anisotropic Sobolev-Besov spaces, and anisotropic fractional Sobolev spaces. The methods used are based on non-increasing rearrangements, and on estimates of sections of functions and sections of sets. We also study limiting relations between embeddings of spaces of different type. More exactly, mixed norm estimates enable us to get embedding constants with sharp asymptotic behaviour. This gives an extension of the results obtained for isotropic Besov spaces by Bourgain, Brezis, and Mironescu, and for anisotropic Besov spaces by Kolyada.

    We study also some basic properties (in particular the approximation properties) of special weak type spaces that play an important role in the construction of mixed norm spaces, and in the description of Sobolev type embeddings.

    In the last chapter, we study mixed norm spaces consisting of functions that have smooth sections. We prove embeddings of these spaces to Lorentz spaces. From this result, known properties of Sobolev-Liouville spaces follow.

    Fulltekst (pdf)
    FULLTEXT01
  • 30.
    Algervik, Robert
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för matematik.
    Embedding Theorems for Mixed Norm Spaces and Applications2008Licentiatavhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    This thesis is devoted to the study of mixed norm spaces that arise in connection with embeddings of Sobolev and Besov type spaces. The work in this direction originates in a paper due to Gagliardo (1958), and was continued by Fournier (1988) and by Kolyada (2005).

    We consider fully anisotropic mixed norm spaces. Our main theorem states an embedding of these spaces into Lorentz spaces. Applying this result, we obtain sharp embedding theorems for anisotropic fractional Sobolev spaces and anisotropic Sobolev-Besov spaces. The methods used are based on non-increasing rearrangements and on estimates of sections of functions and sections of sets. We also study limiting relations between embeddings of spaces of different type. More exactly, mixed norm estimates enable us to get embedding constants with sharp asymptotic behaviour. This gives an extension of the results obtained for isotropic Besov spaces $B_p^\alpha$ by Bourgain, Brezis, and Mironescu, and for Besov spaces $B^{\alpha_1,\dots,\alpha_n}_p$ by Kolyada.

    We study also some basic properties (in particular the approximation properties) of special weak type spaces that play an important role in the construction of mixed norm spaces and in the description of Sobolev type embeddings.

    Fulltekst (pdf)
    FULLTEXT01
  • 31.
    Algervik, Robert
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för matematik.
    Kolyada, Viktor
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för matematik.
    On Fournier-Gagliardo mixed norm spaces2011Inngår i: Annales Academiae Scientiarum Fennicae Mathematica, ISSN 1239-629X, Vol. 36, s. 493-508Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We study mixed norm spaces

    V (Rn)

    that arise in connection with embeddings of

    Sobolev spaces

    W

    1

    1

    (Rn). We prove embeddings of V (Rn)

    into Lorentz type spaces defined in terms

    of iterative rearrangements. Basing on these results, we introduce the scale of mixed norm spaces

    V

    p

    (Rn). We prove that V ½ V p

    and we discuss some questions related to this embedding.

  • 32. Ali, A
    et al.
    Hoagg, J. B
    Mossberg, Magnus
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för fysik och elektroteknik.
    Bernstein, D. S
    Growing window recursive quadratic optimization with variable regularization2010Konferansepaper (Fagfellevurdert)
  • 33.
    Ali, Agha Rehmat
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för fysik och elektroteknik.
    Predicted Speed Control based on Fuzzy Logic for Belt Conveyors: Fuzzy Logic Control for Belt Conveyors2018Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Abstract [en]

    In order to achieve energy savings for belt conveyor system, speed control provides one of the best solutions. Most of the traditional belt conveyors used in the industries are based on constant speed for all operational times. Due to the need and advancements in technology, Variable Frequency Drives (VFD) are employed in industries for a number of processes. Passive Speed Control was previously suggested for the proper utilization of VFD to make belt conveyor systems more power e- cient with increased life expectancy and reduced environmental eects including the noise reduction caused by constant speed of operation. Due to certain conditions and nature of operation of belt conveyor systems, it is not desirable to use Passive Speed control where feeding rate is random. Due to the extreme non-linearity of the random feeding rate, an Active speed control for VFD is desired which adjusts belt speed according to the material loading. In this thesis an Active Speed control for VFD is proposed that can achieve energy and cost ecient solutions for belt conveyor systems as well as avoiding half-lled belt operations. The aim of this thesis work is primarily to determine reliability and validity of Active Speed Control in terms of power savings. Besides achieving power savings, it is also necessary to check the economic feasibility. A detailed study is performed on the feasibility of Active Speed Control for random feeding rate according to industrial requirements. Due to the random and non-linearity of the material loading on the belt conveyor systems, a fuzzy logic algorithm is developed using the DIN 22101 model. The developed model achieves Active Speed Control based on the feeding rate and thereby optimizes the belt speed as required. This model also overcomes the risks of material spillage, overloading and sudden jerks caused due to unpredicted rise and fall during loading. The model conserves 20- 23% of the total power utilized compared to the conventional conveyor systems in use. However it is noticed that the peak power of conventional conveyor belt systems is up to 16% less compared to the proposed model. If implemented in dierent industries, based on the operational time and total consumption of electricity, the proposed Active speed control system is expected to achieve economic savings up to 10-12 % .

    Fulltekst (pdf)
    fulltext
  • 34. Almgren, M
    et al.
    Alsins, J
    Mukhtar, E
    van Stam, Jan
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemi och biomedicinsk vetenskap. Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap.
    Diffusion-Controlled Fluorescence Quenching in Micelles1989Inngår i: Reactions in Compartmentalized Liquids; Knoche W and Shomacker R (eds), Springer-Verlag, Berlin Heidelberg (1989), 61-68, 1989Kapittel i bok, del av antologi (Fagfellevurdert)
  • 35. Almgren, M.
    et al.
    Alsins, J.
    Mukhtar, E.
    van Stam, Jan
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemi och biomedicinsk vetenskap. Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap.
    Fluorescence Quenching Dynamics in Rodlike Micelles1988Inngår i: J. Phys. Chem., 1988, 92, 4479-4483Artikkel i tidsskrift (Fagfellevurdert)
  • 36. Almgren, M
    et al.
    Alsins, J
    van Stam, Jan
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemi och biomedicinsk vetenskap. Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap.
    Mukhtar, E
    The micellar sphere-to-rod transition in CTAC-NaClO3. A fluorescence quenching study1988Inngår i: Progr. Colloid Polym. Sci., 1988, 76, 68-74Artikkel i tidsskrift (Fagfellevurdert)
  • 37. Almgren, M.
    et al.
    Hansson, P.
    Mukhtar, E.
    van Stam, Jan
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemi och biomedicinsk vetenskap. Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap.
    Aggregation of Alkyltrimethylammonium Surfactants in Aqueous Poly(styrenesulfonate) Solutions1992Inngår i: Langmuir, 1992, 8, 2405-2412Artikkel i tidsskrift (Fagfellevurdert)
  • 38. Almgren, M.
    et al.
    Löfroth, J-E
    van Stam, Jan
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemi och biomedicinsk vetenskap. Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap.
    Fluorescence Decay Kinetics in Monodisperse Confinements with Exchange of Probes and Quenchers1986Inngår i: J. Phys. Chem., 1986, 90, 4431-4437Artikkel i tidsskrift (Fagfellevurdert)
  • 39. Almgren, M.
    et al.
    van Stam, Jan
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemi och biomedicinsk vetenskap. Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap.
    Lindblad, C.
    Li, P.
    Stilbs, P.
    Bahadur, P.
    Aggregation of Poly(ethyelene oxide)-Poly(propylene oxide)-Poly(ethylene oxide) Triblock Copolymers in the Presence of Sodium Dodecyl Sulfate in Aqueous Solution1991Inngår i: J. Phys. Chem., 1991, 95, 5677-5684Artikkel i tidsskrift (Fagfellevurdert)
  • 40. Almgren, M
    et al.
    van Stam, Jan
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemi och biomedicinsk vetenskap. Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap.
    Swarup, S
    Löfroth, J-E
    Structure and Transport in the Microemulsion Phase of the System Triton X-100-Toluene-Water1986Inngår i: Langmuir, 1986, 2, 432-438Artikkel i tidsskrift (Fagfellevurdert)
  • 41.
    Almlöf Ambjörnsson, Heléne
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik.
    Germgård, Ulf
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik.
    Enzyme treatment of dissolving pulps as a way to improve the following dissolution of the fibres2012Konferansepaper (Annet vitenskapelig)
  • 42.
    Almlöf Ambjörnsson, Heléne
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik.
    Germgård, Ulf
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik.
    Extended Mercerization Prior to Carboxymethyl Cellulose Preparation2011Konferansepaper (Annet (populærvitenskap, debatt, mm))
  • 43.
    Almlöf Ambjörnsson, Heléne
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik.
    Germgård, Ulf
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik.
    Jardeby, Kristina
    Borregaard Chemcell, Sarpsborg, Norge.
    Kreutz, Björn
    Borregaard Chemcell, Sarpsborg, Norge.
    The influence of mercerization on the degree of substitution in carboxymethyl cellulose2009Konferansepaper (Annet (populærvitenskap, debatt, mm))
  • 44.
    Almlöf Ambjörnsson, Heléne
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik.
    Schenzel, Karla
    Marthin-Luther University Halle-Wittenberg.
    Germgård, Ulf
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik.
    Characterization of CMC by NIR FT Raman spectroscopy2012Konferansepaper (Annet (populærvitenskap, debatt, mm))
  • 45.
    Almlöf, Heléne
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik.
    Extended Mercerization Prior to Carboxymethyl Cellulose Preparation2010Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Carboxymethyl cellulose (CMC) is produced commercially in a two-stage process consisting of a mercerization stage, where the pulp is treated with alkali in a water alcohol solution, followed by an etherification stage in which monochloroacetic acid is added to the pulp slurry. In this thesis an extended mercerization stage of a spruce ether pulp was investigated where the parameters studied were the ratio of cellulose I and II, concentration of alkali, temperature and retention time. The influence of the mercerization stage conditions on the etherification stage, were evaluated as the degree of substitution (DS) of the resulting CMC and the filterability of CMC dissolved in water at a concentration of 1%. The DS results suggested that the NaOH concentration in the mercerization stage was the most important of the parameters studied. When the NaOH concentration in the mercerization step was low (9%), a high cellulose II content in the pulp used was found to have no negative impact on the DS of the resulting CMC compared with pulps with only cellulose I. However, when the NaOH concentration was high (27.5%), pulps with high content of cellulose II showed a lower reactivity than those with only cellulose I with respect to the DS of the CMC obtained after a given charge of NaMCA.

    The results obtained from the filtration ability study of CMC water solutions suggested that both the amount of cellulose II in the original pulp and the temperature had a negative influence on the filtration ability whereas the NaOH concentration in the mercerization stage had a positive influence. The filtration ability was assumed to be influenced highly by the presence of poorly reacted cellulose segments. A retention time between 1-48 h in the mercerization stage had no effect on either the DS or the filtration ability of the CMC.

    Using NIR FT Raman spectroscopy molecular structures of CMC and its gel fraction were analyzed with respect to the conditions used in the extended mercerization stage. Here it was found that the alkaline concentration had a very strong influence on the following etherification reaction. FT Raman spectra of CMC samples and their gel fractions prepared with low NaOH concentrations (9%) in the mercerization stage indicated an incomplete transformation of cellulose to Na-cellulose before carboxymethylation to CMC. Low average DS values of the CMC, i.e. between 0.42 and 0.50, were yielded. Such CMC dissolved in water caused very thick and semi solid gum-like gels, probably due to an uneven distribution of substituting groups along the cellulose backbone. FT Raman spectra of CMC mercerized with alkaline concentrations at 18.25 and 27.5% in the mercerization stage indicated, however, that all of the cellulose molecules were totally transferred to CMC of high DS, i.e. between 0.88 and 1.05. When dissolved in water such CMC caused gels when they were prepared from ether pulp with a high fraction of cellulose II.

    Fulltekst (pdf)
    FULLTEXT01
  • 46.
    Almlöf, Heléne
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik.
    Basta, Jiri
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik.
    Germgård, Ulf
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik.
    Guo, Sanchuan
    Heijnesson-Hulten, Anette
    The Effect of Stock Storage on The Quality of Bamboo Kraft Pulp2010Inngår i: O PAPEL, ISSN 0031-1057, Vol. 72, nr 6, s. 43-53Artikkel i tidsskrift (Fagfellevurdert)
  • 47.
    Almlöf, Heléne
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik.
    Kreutz, Bjørn
    Borregaard Chemcell, Norway.
    Jardeby, Kristina
    Borregaard Chemcell, Norway.
    Germgård, Ulf
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik.
    The influence of extended mercerization on some properties of carboxymethyl cellulose (CMC)2012Inngår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 66, s. 21-27Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Carboxymethyl cellulose (CMC) is produced commercially in a two stage process consisting of a mercerization stage in which the pulp is treated with alkali in a water alcohol solution and a second etherification stage whereby monochloro-acetic acid is added to the pulp slurry. In this study, the influence of the conditions of an extended mercerization stage was evaluated on the etherification stage concerning the degree of substitution (DS) and the filterability of the resulting CMC. The parameters studied were: (1) the ratio of cellulose I and cellulose II in the original pulp, (2) the concentration of alkali, (3) the temperature and (4) the retention time in the mercerization stage. The DS results indicate that the NaOH concentration in the mercerization stage is the most important among the parameters studied. When the NaOH concentration in the mercerization stage was high (27.5%), cellulose II showed a lower reactivity than cellulose I with respect to the DS obtained in the resulting CMC. The results from the filtration ability of CMC water solutions are interpreted that the amount of cellulose II in the original pulp and the temperature has a negative influence, while the NaOH concentration in the mercerization stage has a positive influence on the filtration ability. Retention time between 1 h–48 h in the mercerization stage had no effect on the DS or the filtration value. The filtration ability was assumed to be highly influenced by the presence of poorly reacted cellulose segments. The CMC samples with the lowest filtration ability at a given DS can be assumed to have the highest degree of unevenly substituted segments.

  • 48.
    Almlöf, Heléne
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik.
    Schenzel, Karla
    Department of Natural Science III, Institute of Agriculture and Nutritional Science, Martin Luther University, Germany.
    Germgård, Ulf
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik.
    Carboxymethyl cellulose produced at different mercerization conditions and characterized by NIR FT Raman spectroscopy and chemometric methods2013Inngår i: BioResources, E-ISSN 1930-2126, Vol. 8, nr 2, s. 1918-1932Artikkel i tidsskrift (Fagfellevurdert)
  • 49.
    Almqwist, Jonas
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap.
    Olsson, Robert
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap.
    Val av fönster med hjälp multikriterieanalys: Forshaga vårdcentral2009Independent thesis Basic level (university diploma), 15 poäng / 22,5 hpOppgave
    Abstract [sv]

    Rapporten är tänkt som ett hjälpmedel vid fönsterprojektering och berör de aspekter som är av intresse vid val av fönster. Målgruppen är Landstingsfastigheter i Värmland (LIV) samt alla som har intresse av ämnet. Huvudsyftet är att förenkla för LIV i deras arbete att välja fönster och att lämna förslag på den bästa fönster-/solskyddslösningen till vårdcentralen i Forshaga.

    Målet med rapporten är att skapa ett verktyg som hjälper LIV att på ett objektivt och enkelt sätt välja sina framtida fönster-/solskyddslösningar.

     

    Med hjälp av en multikriterieanalys (MKA) i samverkan med uppställda mål och syften har en mall arbetats fram, där fönster/solskydd kan utvärderas på ett objektivt sätt. MKA:n fungerar bra vid jämförelse av fönster men inte vid solskydd. Detta eftersom LIV har satt upp tydliga mål och syften för sin solskyddslösning. Därmed har en undersökande metod med hjälp av LIV:s uppställda krav använts som hjälpmedel vid val av solskyddslösning. MKA-metoden tillämpades för att finna det bästa fönstret till vårdcentralen i Forshaga.

     

    Rapporten visar att med LIV:s förutsättningar är den bästa lösningen ett PVC-fönster med isolerglas. PVC-karmen är den lösning som ger lägst U-värde samt kostar minst i sammanhanget. Trots att PVC-fönstret redovisas som vinnare var det inte bäst i alla avseenden. Aluminiumfönstret är genomgående bra och bäst ur säkerhetssynpunkt men tillverkarna har svårt att minska de naturliga köldbryggorna som uppstår i karmen. Lösningarna blir dyra och fönstret är svårt att motivera ekonomiskt när säkerhetskraven är normala. Fönster med trä respektive trä-/aluminiumkarm får också ett genomgående gott betyg. Ur underhållssynpunkt har träkarmen svårt att mäta sig med de underhållsfria alternativen.

     

    Eftersom LIV har tydliga krav och mål uppställda på sina solskyddslösningar och på deras funktion, sorterades många lösningar bort. Skärningspunkten för alla kriterier föll på en fast solavskärmning som inte kräver något underhåll, eller vars funktion förändras av väder och vind. Solavskärmningen bör kombineras med en persienn för att möjliggöra ett gott insynsskydd.

    En slutsats vid val av fönster är att det är viktigt att ha tydliga mål och syften, först när det är färdigställt kan man gå vidare med vilken funktion och krav fönstret/solskyddet bör uppfylla.

  • 50.
    Almström, Linda
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap.
    Söderström, Camilla
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap.
    Alternative materials for high-temperature and high-pressure valves2010Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    AB SOMAS Ventiler manufactures valves for different applications. A valve of type DN VSSL 400, PN 100, used in high-temperature and high-pressure applications was investigated in this thesis. This type of valve is coated with high cobalt alloys to achieve the tribological properties needed for this severe condition. However there is a request from AB Somas Ventiler to find another solution. This request is based on the fact that demands on higher temperatures, from customers, yields higher requirements on the material. It is also a price issue since cobalt is quite expensive. Materials investigated were high-nitrogen steel, Vanax 75, nickel-based superalloy Inconel 718 and hardened steels, EN 1.4903 and EN 1.4923 presently used as base material in the valve.

    Calculation of contact pressure that arises when the valve is closed was first approached by using finite element method (FEM). Several models were constructed to show the behavior of the valve during closing in terms of deformation. Hot wear tests, in which a specimen was pressed against a rotating cylinder, were performed to be able to compare the materials to the solution of today and among each other. Data extracted from the tests were compiled in the form of coefficients of friction. Profilometer examinations were used to reveal the volumes of worn and adhered material and together with scanning electron microscopy (SEM) the wear situation for each material couple could be assessed.

    Wear mechanisms detected in SEM were adhesive and abrasive and the results clearly showed that the steels were not a good solution because of severe adhesive wear due to the similarity of mating materials creating a more efficient bonding between the asperities. Vanax 75 showed much better performance but there was still an obvious difference between the steels and the superalloy in terms of both coefficient of friction and amount of wear. On this basis, Inconel 718 was selected as the most suitable material to replace the high cobalt alloys used in the valves today.

    Fulltekst (pdf)
    Alternative materials for high-temperature and high-pressure valves
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