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  • 3701.
    Winter, Philipp
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Towards a Censorship Analyser for Tor2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    Analysing censorship incidents targeting popular circumvention tools such as Tor can be a tedious task. Access to censoring networks is typically difficult to obtainand remote analysis is not always possible. Analysis is however feasible if users behind the censoring networks are given the opportunity to help. In this paper, we propose a lightweight censorship analyser for Tor which is meant to be run by volunteering users. The analyser automatically gathers relevant data and the final report is sent back to the Tor developers. Our design builds on existing software and should be easy to bundle and deploy.

  • 3702.
    Winter, Philipp
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Crandall, Jedidiah R.
    The Great Firewall of China: How it Blocks Tor and Why it is Hard to Pinpoint2012Ingår i: Login: The Usenix Magazine, ISSN 1044-6397, E-ISSN 2169-9364, ISSN 1044-6397, Vol. 37, nr 6, s. 42-50Artikel i tidskrift (Övrigt vetenskapligt)
  • 3703.
    Winter, Philipp
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap. Princeton University.
    Ensafi, Roya
    Princeton University.
    Loesing, Karsten
    The Tor Project.
    Feamster, Nick
    Princeton University.
    Identifying and characterizing Sybils in the Tor network2016Ingår i: Proceedings of the 25th USENIX Security Symposium, USENIX - The Advanced Computing Systems Association, 2016, s. 1169-1185Konferensbidrag (Refereegranskat)
    Abstract [en]

    Being a volunteer-run, distributed anonymity network, Tor is vulnerable to Sybil attacks. Little is known about real-world Sybils in the Tor network, and we lack practical tools and methods to expose Sybil attacks. In this work, we develop sybilhunter, a system for detecting Sybil relays based on their appearance, such as configuration; and behavior, such as uptime sequences. We used sybilhunter’s diverse analysis techniques to analyze nine years of archived Tor network data, providing us with new insights into the operation of real-world attackers. Our findings include diverse Sybils, ranging from botnets, to academic research, and relays that hijacked Bitcoin transactions. Our work shows that existing Sybil defenses do not apply to Tor, it delivers insights into realworld attacks, and provides practical tools to uncover and characterize Sybils, making the network safer for its users.

  • 3704.
    Winter, Philipp
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Lindskog, Stefan
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    How China Is Blocking Tor2012Rapport (Övrigt vetenskapligt)
    Abstract [en]

    Not only the free web is victim to China’s excessive censorship, but also the Tor anonymity network: the Great Firewall of China prevents thousands of potential Tor users from accessing the network. In this paper, we investigate how the blocking mechanism is implemented, we conjecture how China’s Tor blocking infrastructure is designed and we propose countermeasures. Our work bolsters the understanding of China’s censorship capabilities and thus paves the way towards more effective evasion techniques.

  • 3705.
    Winter, Philipp
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Lindskog, Stefan
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    How the Great Firewall of China is Blocking Tor2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    Internet censorship in China is not just limited to the web: the Great Firewall of China prevents thousands of potential Tor users from accessing the network. In this paper, we investigate how the blocking mechanism is implemented, we conjecture how China's Tor blocking infrastructure is designed and we propose circumvention techniques. Our work bolsters the understanding of China's censorship capabilities and thus paves the way towards more effective circumvention techniques.

  • 3706.
    Winter, Philipp
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Lindskog, Stefan
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Spoiled Onions: Exposing Malicious Tor Exit Relays2014Rapport (Övrigt vetenskapligt)
    Abstract [en]

    Several hundred Tor exit relays together push more than 1 GiB/s of network traffic. However, it iseasy for exit relays to snoop and tamper with anonymised network traffic and as all relays are runby independent volunteers, not all of them are innocuous.

    In this paper, we seek to expose malicious exit relays and document their actions. First, wemonitored the Tor network after developing a fast and modular exit relay scanner. We implementedseveral scanning modules for detecting common attacks and used them to probe all exit relays over aperiod of four months. We discovered numerous malicious exit relays engaging in different attacks.To reduce the attack surface users are exposed to, we further discuss the design and implementationof a browser extension patch which fetches and compares suspicious X.509 certificates overindependent Tor circuits.

    Our work makes it possible to continuously monitor Tor exit relays. We are able to detect andthwart many man-in-the-middle attacks which makes the network safer for its users. All our code isavailable under a free license.

  • 3707.
    Winter, Philipp
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Pulls, Tobias
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Fuss, Juergen
    Upper Austria University of Applied Sciences.
    ScrambleSuit: A Polymorphic Network Protocol to Circumvent Censorship2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    Deep packet inspection technology became a cornerstone of Internet censorship by facilitating cheap and effective filtering of what censors consider undesired information. Moreover, filtering is not limited to simple pattern matching but makes use of sophisticated techniques such as active probing and protocol classification to block access to popular circumvention tools such as Tor. In this paper, we propose ScrambleSuit; a thin protocol layer above TCP whose purpose is to obfuscate the transported application data. By using morphing techniques and a secret exchanged out-of-band, we show that ScrambleSuit can defend against active probing and other fingerprinting techniques such as protocol classification and regular expressions. We finally demonstrate that our prototype exhibits little overhead and enables effective and lightweight obfuscation for application layer protocols.

  • 3708.
    Winter, Philipp
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Pulls, Tobias
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Fuss, Juergen
    Upper Austria University of Applied Sciences.
    ScrambleSuit: A Polymorphic Network Protocol to Circumvent Censorship2013Rapport (Övrigt vetenskapligt)
    Abstract [en]

    Deep packet inspection technology became a cornerstone of Internet censorship by facilitating cheap and effective filtering of what censors consider undesired information. Moreover, filtering is not limited to simple pattern matching but makes use of sophisticated techniques such as active probing and protocol classification to block access to popular circumvention tools such as Tor.

    In this paper, we propose ScrambleSuit; a thin protocol layer above TCP whose purpose is to obfuscate the transported application data. By using morphing techniques and a secret exchanged out-of-band, we show that ScrambleSuit can defend against active probing and other fingerprinting techniques such as protocol classification and regular expressions.

    We finally demonstrate that our prototype exhibits little overhead and enables effective and lightweight obfuscation for application layer protocols.

  • 3709. Wisur, H.
    et al.
    Sjöberg, Lars-Arne
    Ahlgren, P.
    Selecting a Potential Swedish Fibre Crop1993Övrigt (Övrig (populärvetenskap, debatt, mm))
  • 3710.
    Witos, Joanna
    et al.
    Univ Helsinki, Dept Chem, Chem Anal Lab, FIN-00014 Helsinki, Finland..
    Samuelsson, Jörgen
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper.
    Cilpa-Karhu, Geraldine
    Univ Helsinki, Dept Chem, Chem Anal Lab, FIN-00014 Helsinki, Finland..
    Metso, Jari
    Nat Inst Hlth & Welf, Publ Hlth Genom Unit, Biomedicum, FIN-00290 Helsinki, Finland..
    Jauhiainen, Matti
    Nat Inst Hlth & Welf, Publ Hlth Genom Unit, Biomedicum, FIN-00290 Helsinki, Finland..
    Riekkola, Marja-Liisa
    Univ Helsinki, Dept Chem, Chem Anal Lab, FIN-00014 Helsinki, Finland..
    Partial filling affinity capillary electrophoresis including adsorption energy distribution calculations: towards reliable and feasible biomolecular interaction studies2015Ingår i: The Analyst, ISSN 0003-2654, E-ISSN 1364-5528, Vol. 140, nr 9, s. 3175-3182Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this work, a method to study and analyze the interaction data in free solution by exploiting partial filling affinity capillary electrophoresis (PF-ACE) followed by adsorption energy distribution calculations (AED) prior model fit to adsorption isotherms will be demonstrated. PF-ACE-AED approach allowed the possibility to distinguish weak and strong interactions of the binding processes between the most common apolipoprotein E protein isoforms (apoE2, apoE3, apoE4) of high density lipoprotein (HDL) and apoE-containing HDL2 with major glycosaminoglycan (GAG) chain of proteoglycans (PGs), chondroitin-6-sulfate (C6S). The AED analysis clearly revealed the heterogeneity of the binding processes. The major difference was that they were heterogeneous with two different adsorption sites for apoE2 and apoE4 isoforms, whereas interestingly for apoE3 and apoE-containing HDL2, the binding was homogeneous (one site) adsorption process. Moreover, our results allowed the evaluation of differences in the binding process strengths giving the following order with C6S: apoE-containing HDL2 > apoE2 > apoE4 > apoE3. In addition, the affinity constant values determined could be compared with those obtained in our previous studies for the interactions between apoE isoforms and another important GAG chain of PGs - dermatan sulfate (DS). The success of the combination of AED calculations prior to non-linear adsorption isotherm model fit with PF-ACE when the concentration range was extended, confirmed the power of the system in the clarification of the heterogeneity of biological processes studied.

  • 3711.
    Worén, Felix
    Karlstads universitet, Fakulteten för humaniora och samhällsvetenskap (from 2013), Handelshögskolan (from 2013).
    Eye-tracking för mobila enheter: En utvärdering av problemen med eye-tracking för mobila enheter vid användartestning2018Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Eye‐tracking är en metod för användartester. Det kan visa var testpersoner tittar, vad de missar och  vad som väcker uppmärksamhet. Ett problem med eye‐tracking i nuläget är dess dåliga precision.  Mobiler och andra mobila enheters skärmyta kan vara väldigt liten, vilket resulterar i att det inte finns  mycket rum för fel i en eye‐tracker. Syftet med den undersökning som rapporteras här är att  utvärdera problemen med eye‐tracking i utvärderingar av användargränssnitt för mobila enheter. För  att utvärdera detta har några tester utformade av mig utförts, där testpersonerna har fått välja  mellan att använda sin egen telefon, en iPhone 7 eller en iPad och sedan utfört några uppgifter på  olika applikationer/hemsidor. Pilottester från ett projekt vid namn CREDENTIAL har även bidragit till  denna studie där testpersonerna har fått utföra eye‐tracking‐tester på en Microsoft Surface Pro.  Resultaten är presenterade i form av grafiska representationer av datan, med hjälp av heat maps och  gaze plots. Resultaten visar hur problemen med eye‐tracking för mobila enheter kan störa  användartester för system på mobila enheter. 

  • 3712.
    Wuerflinger, Sabrina
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013).
    Risk Analysis for eHealth Cloud Services2013Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
  • 3713. Wulff, Felix
    Förbättring av flöde och ökad produktion: Förändringar med syfte att möta en tillväxt2016Självständigt arbete på grundnivå (högskoleexamen), 15 poäng / 22,5 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Arbetet har utförts på AnVa Polytech AB som i huvudsak producerar formsprutade gummidetaljer. Arbetet har delats upp i två huvudrubriker, vad som krävs av företagets produktionsanläggning i syfte att möta en önskad tillväxt och hur företaget kan skapa effektiva flöden i produktionen.

    AnVa Polytech AB har ett tillväxtmål på 10% per år. I arbetet har det undersökts vilken förändring det innebär i tillverkningsvolym. Därefter har utrustningen i produktionen kartlagts genom att nuvarande kapacitet samt framtida kapacitet har undersökts. Resultatet är vilka förändringar i form av utrustning och då framförallt formsprutningsmaskiner som krävs.

    Företaget arbetar efter lean som en uttalad affärsstrategi. Inom lean är arbetet för flödeseffektivitet centralt. Den andra delen av arbetet har därför behandlat hur AnVa Polytech AB kan nå längre i arbetet mot flödeseffektivitet. Det innefattar en värdeflödesanalys med tillhörande spagettidiagram och PICK-chart. Även en analys av optimal flödesprincip för företaget har genomförts. Arbetet mot flödeseffektivitet har tillsammans med analysen av utrustningen i produktionen resulterat i en fabrikslayout.

    Arbetet förklarar vad AnVa Polytech AB bör göra kommande fem år.

  • 3714.
    Wäne, Gerd
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik.
    Fibre surface properties of kraft pulp: The influence of wood raw material, bleaching and storage2009Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The aim of this thesis was to study the fibre surface properties of Birch (Betula ssp.), Eucalyptus (E. urograndis and E. globulus) and Spruce (Picea Abies) pulps bleached using two different methods: ECF (Elementary Chlorine Free) and TCF (Totally Chlorine Free). The hardwood pulps were subjected to a hot acidic stage prior to ECF bleaching in order to remove hexenuronic acid. The effect of prolonged storage (ageing) on the fibre surface properties was studied for all of the pulps.

    The characteristics of the fibre surfaces were determined by measuring the dynamic contact angle of single fibres (DCA) and by using Electron Spectroscopy for Chemical Analysis (ESCA) and Time of Flight Secondary Ion Mass Spectroscopy (ToF-SIMS). The correlation between the fibre surface properties and the sizing efficiency of the hardwood pulps were evaluated by measuring the amount of alkyl ketene dimer (AKD) needed to reach a certain water absorption level(measured as Cobb60).

    The birch pulp was more hydrophilic than the eucalyptus pulps, thus requiring more AKD to reach a certain water absorption value, and also had a lower DCA. The introduction of a hot acidic stage (A stage) in the ECF bleaching sequence applied to the hardwood pulps (i.e. A/D(EP)DD versus D(EP)DD) lowered, as expected, the total fibre charge due to the removal of hexenuronic acids groups (HexA). According to the DCA measurements all of the pulps became more hydrophilic after the A/D(EP)DD bleaching than after the D(EP)DD bleaching sequence. The sizing ability of the pulps, measured as the AKD demand to a certain Cobb60 value, showed that the AKD demand was more or less the same for the eucalyptus pulps regardless of the bleaching sequence used. The birch pulp, on the other hand, required somewhat less AKD in the A/D(EP)DD sequence than in the D(EP)DD.

    The AKD demand to a certain Cobb60 value decreased further for the bleached birch and E. globulus pulps after ageing due to an increase in the fibre surface hydrophobicity. ESCA analysis revealed an increase of surface extractives on the pulps after ageing, which was also supported by ToF-SIMS analysis. It was concluded that there was an increase in fatty acids, fatty acid salts and possibly even sterols and glycerides on the fibre surfaces due to ageing. A migration of these components from the interior of the fibre wall to the fibre surface during ageing was verified in this study.

    The TCF and ECF bleached softwood pulps also showed differences in their fibre surface properties that were tangible and thereby measurable. The dynamic contact angle was highest for the TCF bleached softwood fibres, i.e. these were more hydrophobic. Although changes caused by ageing were much more pronounced for the ECF fibres, all pulps became more hydrophobic upon ageing.

    The hydrophobicity of pulp fibres can be determined using DCA, which is a rather rapid and economically viable analysis. Using this information, a paper/board mill can base its sizing strategy on scientific findings.

    The ageing effects seen on the fibre surfaces in the form of the migration of extractives might be an important parameter from an industrial point of view, especially when pulps are stored and/or transported for a long time period. Nowadays it is quite common for pulps to be shipped around the world and subjected to warm and humid conditions. It is therefore probable that the properties of the pulp change in such a way that the papermaking process requires adjustment.

  • 3715.
    Wäne, Gerd
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik.
    Germgård, Ulf
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik.
    Aspects on the AKD demand of hardwood kraft pulps before and after ageing2009Ingår i: Appita journal, ISSN 1038-6807, Vol. 62, nr 2, s. 123-129Artikel i tidskrift (Refereegranskat)
  • 3716.
    Wäne, Gerd
    et al.
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik.
    Germgård, Ulf
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemiteknik.
    Pulp and Fibre surface properties of bleached hardwood Kraft Pulps: Influence of an A-stage2009Ingår i: Paperi ja puu, ISSN 0031-1243, Vol. 91, nr 7-8, s. 58-64Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Hexenuronic acids in kraft pulps increase the demand for bleaching chemicals and cause brightness reversion of the bleached pulps during storage. They can, however, be removed by the use of hot acid treatments in e.g. the bleaching sequence, which is commonly used for eucalyptus in the pulp industry today. In this work three kraft hardwood pulps (two eucalyptus and one birch) were selected to study the influence on the surface properties of the pulps of a hot acidic stage (A stage) introduced prior to a standard ECF bleaching sequence. The sequences compared were A/D(EP)DD and D(EP)DD. The results were compared before and after the pulps were aged at room temperature for about eight months.

  • 3717.
    Wästlund, Erik
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för psykologi. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för tjänsteforskning.
    Angulo, Julio
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Fischer-Hübner, Simone
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Evoking Comprehensive Mental Models of Anonymous Credentials2012Ingår i: Proceedings of the 2011 IFIP WG 11.4 international conference on Open Problems in Network Security / [ed] Camenisch J., Kesdogan, D., Berlin: Springer Berlin/Heidelberg, 2012, Vol. 7039, s. 1-14Konferensbidrag (Refereegranskat)
    Abstract [en]

    Anonymous credentials are a fundamental technology for preserving end users' privacy by enforcing data minimization for online applications. However, the design of user-friendly interfaces that convey their privacy benefits to users is still a major challenge. Users are still unfamiliar with the new and rather complex concept of anonymous credentials, since no obvious real-world analogies exists that can help them create the correct mental models. In this paper we explore different ways in which suitable mental models of the data minimization property of anonymous credentials can be evoked on end users. To achieve this, we investigate three different approaches in the context of an e-shopping scenario: a card-based approach, an attribute-based approach and an adapted card-based approach. Results show that the adapted card-based approach is a good approach towards evoking the right mental models for anonymous credential applications. However, better design paradigms are still needed to make users understand that attributes can be used to satisfy conditions without revealing the value of the attributes themselves.

  • 3718.
    Xinzhu, Jin
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap.
    Channel Estimation Techniques of SC-FDMA2007Självständigt arbete på avancerad nivå (magisterexamen), 20 poäng / 30 hpStudentuppsats
    Abstract [en]

    Abstract

    This master thesis investigates several di®erent channel estimation techniques in an SC-

    FDMA (Single Carrier Frequency Division Multiple Access) system with parameters set

    according to the standards of 3GPP LTE (3rd Generation Partnership Project Long Term

    Evolution). 3GPP LTE is the name given to a project within the 3GPP to improve the

    mobile phone standard to cope with future requirements. In this thesis, we ¯rst introduce

    the SC-FDMA system, which is a transmission technique that utilizes single carrier mod-

    ulation, then ¯ve types of estimators are investigated. Essential to all channel estimatiors

    is the use of pilot symbols. In the last part we compare the performance of the channel

    estimation techniques with each other in di®erent environments by analysing their symbol

    error rates. All simulations are done in a Matlab environment.

  • 3719. Yadoitsev, Igor
    et al.
    Krakhmalev, Pavel
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap. Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik.
    Yadroitsava, Ina
    Hierarchical design principles of selective laser melting for high quality metallic objects2015Ingår i: Additive manufacturing, ISSN 2214-8604, Vol. 7, s. 45-56Artikel i tidskrift (Refereegranskat)
  • 3720. Yadroitsev, I
    et al.
    Krakhmalev, Pavel
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik.
    Yadroitsava, I
    Selective laser melting of Ti6Al4V alloy for biomedical applications: Temperature monitoring and microstructural evolution2014Ingår i: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 583, s. 404-409Artikel i tidskrift (Refereegranskat)
  • 3721.
    Yadroitsev, I.
    et al.
    Cent Univ Technol, Dept Mech & Mechatron Engn, ZA-9300 Bloemfontein, Free State, South Africa.
    Krakhmalev, Pavel
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Yadroitsava, I.
    Cent Univ Technol, Dept Mech & Mechatron Engn, ZA-9300 Bloemfontein, Free State, South Africa.
    Du Plessis, A.
    Univ Stellenbosch, CT Scanner Facil, ZA-7602 Stellenbosch, South Africa.
    Qualification of Ti6Al4V ELI Alloy Produced by Laser Powder Bed Fusion for Biomedical Applications2018Ingår i: JOM: The Member Journal of TMS, ISSN 1047-4838, E-ISSN 1543-1851, Vol. 70, nr 3, s. 372-377Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Rectangular Ti6Al4V extralow interstitials (ELI) samples were manufactured by laser powder bed fusion (LPBF) in vertical and horizontal orientations relative to the build platform and subjected to various heat treatments. Detailed analyses of porosity, microstructure, residual stress, tensile properties, fatigue, and fracture surfaces were performed based on x-ray micro-computed tomography, scanning electron microscopy, and x-ray diffraction methods. The types of fracture and the tensile fracture mechanisms of the LPBF Ti6Al4V ELI alloy were also studied. Detailed analysis of the microstructure and the corresponding mechanical properties were compared against standard specifications for conventional Ti6Al4V alloy for use in surgical implant applications. Conclusions regarding the mechanical properties and heat treatment of LPBF Ti6Al4V ELI for biomedical applications are made.

  • 3722.
    Yadroitsev, I
    et al.
    Université de Lyon, France.
    Krakhmalev, Pavel
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Materialvetenskap. Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik.
    Yadroitsava, I
    Université de , France.
    Johansson, S
    Linköpings universitet.
    Smurov, I
    Université de Lyon.
    Energy input effect on morphology and microstructure of selective laser melting single track from metallic powder2013Ingår i: Journal of Materials Processing Technology, ISSN 0924-0136, E-ISSN 1873-4774, Vol. 213, nr 4, s. 606-613Artikel i tidskrift (Refereegranskat)
  • 3723.
    Yadroitsev, Igor
    et al.
    South Africa.
    Krakhmalev, Pavel
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    Yadroitsava, I.
    South Africa.
    A systematic approach to manufacturing parts with desired properties by selective laser melting2015Ingår i: Materials Science and Technology Conference and Exhibition 2015, MS and T 2015, Association for Iron and Steel Technology, AISTECH , 2015, Vol. 1, s. 121-128Konferensbidrag (Refereegranskat)
    Abstract [en]

    Selective laser melting (SLM) is becoming a powerful additive manufacturing technology for different industries: automotive, medical, chemical, aerospace, etc. The extension of applications requires a wide spectrum of powder materials with specific properties. To produce parts with tailored properties by SLM, optimal process-parameters and scanning strategies have to be used for different powders. Numerical simulation allows the estimation of temperature distribution during laser melting and prediction the final microstructures and properties of SLM object. A hierarchical approach, including systematic analysis of SLM parameters necessary to control the final product quality on every level - track, layer, 3D object is suggested and discussed. A series of single tracks, layers and 3D objects were manufactured from metal powders to validate a proposed algorithm. The efficiency of the approach was illustrated by the manufacturing of fully dense samples from AISI 420 stainless steel.

  • 3724. Yadroitsev, Igov
    et al.
    Krakhmalev, Pavel
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Yadroitsava, Inna
    Titanium Alloys Manufactured by In Situ Alloying During Laser Powder Bed Fusion2017Ingår i: JOM: The Member Journal of TMS, ISSN 1047-4838, E-ISSN 1543-1851, Vol. 69, nr 12, s. 2725-2730Artikel i tidskrift (Refereegranskat)
  • 3725.
    Yadroitsev, Igov
    et al.
    Department of Mechanical and Mechatronic Engineering, Bloemfontein, Central University of Technology, Free State, South Africa.
    Krakhmalev, Pavel
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik.
    Yadroitsava, Inna
    Department of Mechanical and Mechatronic Engineering, Bloemfontein, Central University of Technology, Free State, South Africa.
    Du Plessis, Anton
    University of Stellenbosch.
    Qualification of DMLS Ti6Al4V (ELI) alloy for biomedical applications2017Ingår i: Proceedings of the 28th Annual International Solid Freedom Fabrication symposium – an Additive Manufacturing conference 2017 / [ed] David L. Bourell, Richard H. Crawford, Carolyn C. Seepersad, Joseph J. Beaman & Scott Fish, Austin: University of Texas , 2017Konferensbidrag (Refereegranskat)
  • 3726.
    Yaghoubi, Saba Tahaei
    et al.
    Aalto University, Finland.
    Mousavi, Mahmoud
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013). Aalto University, Finland.
    Paavola, Juha
    Aalto University, Finland.
    Size effects on centrosymmetric anisotropic shear deformable beam structures2017Ingår i: Zeitschrift für angewandte Mathematik und Mechanik, ISSN 0044-2267, E-ISSN 1521-4001, Vol. 97, nr 5, s. 586-601Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, the size effect on beam structures with centrosymmetric anisotropy is studied within strain gradient elasticity theory. Applying dimension reduction to the three dimensional anisotropic gradient elasticity, the third-order shear deformable (TSD) beam is analysed. A variational approach is used to determine the equilibrium equations of TSD beam together with consistent (classical and non-classical) boundary conditions. The TSD beam theory which is suitable for deep beam structures can be replaced by (less complicated) Euler-Bernoulli beam model for thin beam structures. The anisotropic Euler-Bernoulli beam model is also formulated within the framework of strain gradient theory. This anisotropic beam theory can be used to study size effects for any types of centrosymmetric anisotropy. To address the more practical cases of composite structures, the formulation is simplified for orthotropic and transversely isotropic materials. Finally, the analytical solutions are provided for bending of simply supported (TSD and Euler-Bernoulli) beams as well as clamped Euler-Bernoulli beams. The effect of the crystal orientation with respect to the beam geometry is investigated in these examples.

  • 3727.
    Yaghoubi, Saba Tahaei
    et al.
    Aalto University, Finland.
    Mousavi, Mahmoud
    Aalto University, Finland.
    Paavola, Juha
    Aalto University, Finland.
    Strain and velocity gradient theory for higher-order shear deformable beams2015Ingår i: Archive of applied mechanics (1991), ISSN 0939-1533, E-ISSN 1432-0681, Vol. 85, nr 7, s. 877-892Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The strain and velocity gradient framework is formulated for the third-order shear deformable beam theory. A variational approach is applied to determine the governing equations together with initial and boundary conditions. Within the gradient framework, the strain energy is generalized to include strain as well as strain gradient. Furthermore, the kinetic energy is also generalized to include velocity and the velocity gradient. Such approach results in the introduction of the static and kinetic internal length scales. For dynamic analysis of beams, most of the gradient theories do not take the velocity gradient into account. The model developed in this paper depicts the influence of the velocity gradient on the governing equations and initial and boundary conditions of the third-order shear deformable theory. Through the assumption of the velocity gradients, kinematic quantities are distinguished on the microscale and on the macroscale. Finally, Timoshenko and Euler–Bernoulli beam theories are also presented by simplifying the third-order theory.

  • 3728.
    Yaghoubi, SabaTahaei
    et al.
    Aalto university, Finland.
    Mousavi, Mahmoud
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013). Aalto university, Finland.
    Paavola, Juha
    Aalto university, Finland.
    Buckling of centrosymmetric anisotropic beam structures within strain gradient elasticity2017Ingår i: International Journal of Solids and Structures, ISSN 0020-7683, E-ISSN 1879-2146, Vol. 109, s. 84-92Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Buckling of centrosymmetric anisotropic beams is studied within strain gradient theory. First, the three dimensional anisotropic gradient elasticity theory is outlined. Then the dimension of the three dimensional theory is reduced, resulting in Timoshenko beam as well as Euler–Bernoulli beam theories. The governing differential equations together with the consistent (classical and non-classical) boundary conditions are derived for centrosymmetric anisotropic beams through a variational approach. By considering von Kármán nonlinear strains, the geometric nonlinearity is taken into account. The obtained nonlinear formulation can be used to study the postbuckling configuration. The analysis of size effect on anisotropic beam structures is missing in the literature so far, while the present model allows one to characterize the size effect on the buckling of the centrosymmetric anisotropic micro- and nano-scale beam structures such as micropillars. As a specific case, the governing buckling equation is obtained for the more practical case of orthotropic beams. Finally, the buckling loads for orthotropic simply supported Timoshenko and Euler–Bernoulli beams as well as a clamped Euler–Bernoulli beam are obtained analytically and the effect of the internal length scale parameters on the buckling load is depicted.

  • 3729. Yang, Li
    Spectral model of halftone on a fluorescent substrate2005Ingår i: J.Imaging Science Technology 49 (2005), 179-184Artikel i tidskrift (Refereegranskat)
  • 3730. Yang, Li
    What has been overlooked in Kubelka-Munk Theory?2005Konferensbidrag (Övrig (populärvetenskap, debatt, mm))
  • 3731. Yang, Li
    et al.
    Fogden, A.
    Pauler, N.
    Sävborg, Ö.
    Kruse, B.
    A novel method for studying ink penetration of a print2005Ingår i: Nordic Pulp and Paper Research Journal 40(2005),423-429Artikel i tidskrift (Refereegranskat)
  • 3732. Yang, Li
    et al.
    Fogden, A.
    Pauler, N.
    Sävborg, Ö.
    Kruse, B.
    Studying ink penetration by microscopic and spectroscopic techniques2006Ingår i: J.Imaging Science and TechnologyArtikel i tidskrift (Refereegranskat)
  • 3733. Yang, Li
    et al.
    Kruse, B.
    Studying ink penetration by microscopic and spectroscopic techniques2005Konferensbidrag (Övrig (populärvetenskap, debatt, mm))
  • 3734. Yang, Li
    et al.
    Miklavcic, S.J.
    Revised Kubelka-Munk theory.III: A general theory of light propagation in scattering and absorptive media2005Ingår i: J.Optical Society of America A 22(9), 1866-1873, (2005)Artikel i tidskrift (Refereegranskat)
  • 3735. Yang, Li
    et al.
    Miklavcic, S.J.
    Theory of light propagation incorporation scattering and absorption in turbid media2005Ingår i: Optics Letter 30(7), 792-794, 2005Artikel i tidskrift (Refereegranskat)
  • 3736.
    Yang, Zhenkun
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för maskin- och materialteknik.
    Alternatives to hard chromium plating on piston rods2011Självständigt arbete på avancerad nivå (masterexamen), 30 poäng / 45 hpStudentuppsats (Examensarbete)
  • 3737.
    Yasir, Irshad
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik, Science, Mathematics and Engineering Education Research (SMEER).
    A study of a stochastic differential equation based model for wireless channels2008Självständigt arbete på avancerad nivå (magisterexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    An autoregressive (AR) first order model is often used for modelling wireless channels. This is done in spite of the fact that a satisfactory physical explanation for this model has been missing. However, in the recent paper [Feng, Field and Haykin. 2007] derive a model in form of a first order stochastic differential equation (SDE) from a stochastic description of the scattered electric field. After discretizing this SDE, a physically motivated first order AR model is obtained.

  • 3738.
    Yedugundla, Kiran
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Hurtig, Per
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Brunström, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Multipath TCP: Can it Reduce Transport Latency for Web Traffic?2015Konferensbidrag (Refereegranskat)
  • 3739.
    Yedugundla, Kiran
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Hurtig, Per
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Brunström, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Probe or Wait: Handling tail losses using Multipath TCP2017Ingår i: 2017 IFIP Networking Conference (IFIP Networking) and Workshops, IEEE, 2017Konferensbidrag (Refereegranskat)
    Abstract [en]

    Packet losses are known to affect the performance of latency sensitive Internet applications such as media streaming and gaming. Transport protocols recover from packet loss in order to provide reliable end-to-end communication and improve user experience. The efficiency of loss recovery mechanisms influences the completion time of flows, and thus also the application performance as perceived by the end user. In this paper we focus on state-of-the-art loss recovery mechanisms for TCP and Multipath TCP. We use controlled tail loss scenarios to evaluate the performance of loss recovery mechanisms and, based on the observations, we propose an enhanced tail loss recovery mechanism for Multipath TCP, to improve the loss recovery time. Our experiment results, using the Linux Multipath TCP implementation, show consistent end-to-end latency performance improvement in considered scenarios.

  • 3740.
    Yohan, Noh
    et al.
    Waseda University.
    Wang, C.
    Waseda University.
    Tokumoto, M.
    Waseda University.
    Solis, Jorge
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för fysik och elektroteknik.
    Ishii, H.
    Waseda University.
    Takanishi, Atsuo
    Waseda University.
    Development of Airway Management Training System WKA-4: Provide Useful Feedback of Trainee Performance to Trainee during Airway Management2012Ingår i: Complex Medical Engineering (CME), 2012 ICME International Conference on, IEEE Press, 2012Konferensbidrag (Refereegranskat)
  • 3741.
    Yong-an, Min
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013). Shanghai University, China.
    Bergström, Jens
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Xiao-chun, Wu
    Shanghai University, China.
    Luo-ping, Xu
    Shanghai University, China.
    Oxidation and Thermal Fatigue Behaviors of Two Type Hot Work Steels During Thermal Cycling2013Ingår i: Journal of Iron and Steel Research International, ISSN 1006-706X, E-ISSN 2210-3988, Vol. 20, nr 11, s. 90-97Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Thermal fatigue test has been carried out on widely used hot work steel 4Cr5MoSiV1 and a low alloyed steel 3Cr3MoV in temperature range of 200 to 700 degrees C. Tempering resistance, as well as high temperature hardness/strength of steel specimens, works as a dominating material parameter on thermal fatigue resistance. During the heating period, high hardness can depress the inelastic deformation. This deformation is the origination of tensile stress, which acts as the driving force of heat checking during the cooling period. The cyclic strain-oxidation interaction can speed up the damage on surface defects, which plays an obvious role in initiation of thermal cracks. On 4Cr5MoSiV1 steel specimens, borders between the matrix and inclusions such as titanium compounds, or lager carbides such as primary carbides, are focused by strain and attacked by oxidation, and are main initiating places of cracks. While on 3Cr3MoV steel specimens, larger strain causes plastic deformation concentrating around grain boundaries. Then the following oxidation accelerates this grain boundary damage and creates cracks.

  • 3742. Yusuf, Abdul Aleem
    Improvement of Oxygen Barrier Properties by Enzyme Technology2012Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
  • 3743.
    zafar, syed hammad
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för fysik och elektroteknik.
    Modelling and control of large wind turbine2013Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    In order to make the wind energy an economical alternative for energy production, upscaling of turbine to 10 - 15MW may be necessary to reduce the overall cost of energy production. This production target requires a considerable increase in the turbine size and placing the turbines at high wind speed locations. But increase in turbine size also increases the uneven load distribution across the turbine structure. Therefore an efficient load reduction technique is necessary to increase the turbine reliability in high wind speed locations. Variable speed wind turbine offers most desirable load reduction through actively pitch angle control of turbine blades. Research has shown that the Individual Pitch Control (IPC) is most promising option for turbine load reduction.

    This thesis work is focused on modelling of a large wind turbine and implementation of a new mutlivariable control concept for turbine load reduction. A detailed mathematical model is designed which includes turbine blade and tower dynamics and a proposed Linear Quadratic Gaussian (LQG) algorithm is implemented for Individual Pitch Control (IPC) loop of wind turbine. Proposed model in this thesis work is derived from the previous turbine model used in ECN with additional tower dynamics. My contribution in turbine modelling portion is to linearize the equations of motion to form a statespace model and to implement LQG algorithm for turbine active load reduction. This proposed method is compared with the previous control technique used in ECN for turbine fatigue load reduction to measure the overall efficiency of the proposed technique.

    Fatigue load has major effect on the turbine working age. In quantitative way, proposed LGQ design offers 8-10% approx. more fatigue load reduction in comparison with the previous design. In simple convention, decrease in turbine fatigue load increases the turbine age. This 8 - 10% fatigue load reduction offers 8 - 10% minimum increase in turbine working age which means that if a turbine works for 20 years in total for energy production, this proposed technique will add 2 extra years into the turbine working life. This age increase has major economic impact to make the wind turbine a viable alternative for energy production.

  • 3744. Zakariasson, Andreas
    Framtagning av OptimalInfästningsmetod av OGV mot Stag för Engine Product Systems Sweden: Development of optimum method of attachment of OGV to brace for Engine Product Systems Sweden2015Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    GKN Aerospace Sweden (GAS) utvecklar och tillverkar motorkomponenter för både den civila och militära flyg-och rymdindustrin. En av produkterna som GKN tillverkar är en outlet guide vane(OGV), vars funktion är att omdirigera det axiella luftflödet från fläkten. OGVn är den mekaniska länken mellan kärnstrukturen och fläkthuset. Ett viktigt mål är att minska vikten på motorn samtidigt som dess diameter ökar när motorerna blivit allt större.

    For att lösa detta krävs ett material med hög hållfasthet i förhallande till vikten. Ett examensarbete som föregår detta har utvecklat ett koncept som innefattar en OGV i en viss GKN-utvecklad tekonologi. Detta examensarbete gjordes för att utveckla ett koncept for den metod som anvönds för att foga OGVn till stagen som ansluter till den inre och yttre kärnan. Detta gjordes genom en konceptstudie som inkluderade konceptgenerering, konceptutvärdering och konceptval.

    Detta resulterade i två möjliga koncept, ett där OGVn och en aluminium-fot monteras med bultning och en där OGVn och en titan-fot svetsades samman. Titanfoten hade fairings i aluminium for att spara lite extra vikt och kostnad.

    Det är tydligt att om integrationen mellan OGV och svets-gränssnittet ska bli en industriell lösning, sa kommer GAS att behöva investera i utveckling för de metoder som används. Det bultade Aluminium-konceptet är att föredra ur leverantörsbas-synpunkt på grund av sin låga tillverknings-och materialkostnad. Trots att kravuppfyllelsen för hållfastheten är tveksam så bör det andå betraktas som en potentiell ersättning for en del av de OGVer i fläkthuset som inte är tungt belastade.

  • 3745.
    Zakariasson, Anton
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013).
    Control functions based on brake actuators in combination with other actuators in new vehicles.2017Självständigt arbete på grundnivå (högskoleexamen), 15 poäng / 22,5 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Dagens fordonsindustri utvecklas i ett rasande tempo där det kommer ny integrerande teknik varje dag som baseras på aktuatorer (ställdon). Denna teknik skapar många nya aktuatorbaserade funktioner och sub-funktioner som alla har olika benämningar och användningsområde inom varje biltillverkares utbud. Arbetet har utförts hos ÅF Industry chassiavdelningen i Trollhättan, Sverige   För att få en tydlig överblick och för att skapa förståelse, så har en benchmarking-process genomförts för en klassisk herrgårdsvagn för att sortera och kategorisera fem olika biltillverkares funktioner. Samma process har även genomförts parallellt av en annan student för bredare resultat. Detta arbete täcker funktioner som är baserade på bromsaktuatorer och bromsaktuatorer i kombination med andra aktuatorer medan den andra studentens arbete täcker andra sorters aktuatorer. Resultatet från bådas benchmarking lades ihop och en sållning gjordes för att avlägsna irrelevanta funktioner för denna rapport. De kvarvarande funktionerna analyserades mer på djupet och ett faktablad skapades där funktion, hur den fungerar, för- och nackdelar, parametrar och pris täcktes. Dessa kommer att användas när ÅFs ingenjörer är osäkra på vad det är för funktion och hur den fungerar.   Utvärdering av Electronic Stability Programme (ESP)- funktionen har gjorts genom testning på NEVS testbana i Trollhättan med avancerad och noggrann testutrustning. En standardiserad testmetod, SS-ISO 3888-2:2011 – Provbana för kraftig undanmanöver – Del 2: Undvikande av hinder, användes genom att köra testbanan i olika hastigheter med ESP aktiverat och med ESP avaktiverat. Genom att låta ESP vara aktiverat så fås ökad kontroll och sladd upphävs effektivt. Det var ingen markant skillnad i resultatet men det var tydligt att ESP:n påverkade kontrollen över fordonet positivt.

  • 3746.
    Zakhoy, Avan
    Karlstads universitet.
    CO2- utsläpp samt upptag hos portlandcement och blandcement under dess livslängd.: Inblandning av flygaska och granulerad masugnsslagg2016Självständigt arbete på grundnivå (yrkesexamen), 15 poäng / 22,5 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The concrete impact on the environment is mainly on cement production, which accounts for 7 percent of total global carbon dioxide emissions. The amount of Carbon dioxide emissions is estimated to 700-800 kilo of carbon dioxide per 1000 kilo of cement produced. About 60 percent of emissions comes from the calcination of limestone, and the remaining 40 percent comes from the burning of fossil fuels due to the heat that must be added during the calcination [2]. Every year it produced around 2 million tonnes of cement in Sweden, which in turn results in the emission of approximately 1.5 million tonnes of carbon dioxide [5].

    A suitable solution has been found in the use of supplementary cementitious materials, also known as mineral admixtures[3]. These materials can be used to replace cement in concrete  as they possess pozzolanic and cementitious properties. The most common industrial by-products used in Sweden at the moment are fly ash and granulated blast furnace slag. To find out how big of an amounts of carbon dioxide emission can be reduced by replacing the parts of the cement with by-products, you have to conciderate the whole concrete life cycle beacuse concrete also ties up carbon dioxide.

    When carbon dioxide  comes in contact with water in the pore solution of the concrete  bicarbonate plus a hydrogen ion is formed. Bicarbonate  is then dissolved to form carbonate  plus a hydrogen ion. When carbonate  comes in contact with calcium, calcium carbonate is formed. This process is called carbonation and continues throughout the life of the concrete. Calcium hydroxide has a very low solubility compared to other hydroxides and will be the first to dissolve and release calcium ions in the pore solution. Calcium silicate stabilized by high pH - value and Ca ions in the pore solution. Calcium Hydroxides releaseing of  lowers the pH content in the pore solution which results in calcium silicate hydrate also begins to dissolve and release ions. However, changing the release of structural reconstruction of Calcium Silicate Hydrate results in a lower Ca / Si - ratio. When this ratio falls to less than 1 and the pH of the pore solution is around 10,  silica gel is formed. Mineral admixtures in form of bee products such as fly ash and granulated blast furnace slag will reduce the amount of calcium hydrate in the cement paste and increase the amount of calcium silicate hydrate.

    Simplification of Fick's second law developed by the CBI has been used in numerical calculations for the concrete's carbon uptake over time. 3 different types of cement, Portland cement, fly ash cement and slag cement has been set against each other from a carbon dioxide perspective.Portland cement: 1 m^3 concrete of type CEM I with strength C30/37 contribute with 263 kg of carbon emissions during production. Over time, this 1 m^3 of concrete have tied up a total of 134 kg of carbon dioxide through carbonation. The total carbon emissions for 1 m^3 concrete of type CEM I with strength C30/37 remains 129 kg.

    Flygaskecement: 1 m^3 concrete of type CEM II / B-V (35% F) with strength C30/37 is contributing with a total of 75 kg of carbon dioxide emissions.

    Slag Cement: 1 m^3 concrete of type CEM II / B-S (35% F) with strength C30/37 is contributing with a total of 41 kg of carbon dioxide emissions.

  • 3747. Zaki, Hazem
    et al.
    Almssad, Asaad
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörs- och kemivetenskaper. Archcrea Institute.
    Thermal earth inertia such a source of energy for bio-sustainable house2005Ingår i: The International Conference Sustainable Building 2005 SB05, Tokyo: SB05Tokyo National Conference Board , 2005, s. 150-153Konferensbidrag (Refereegranskat)
    Abstract [en]

    The earth is our sustainer, the chain of ecologic survival. Renew ability is the key to our human continuum and our prime resource for architecture. Earth sheltering earth handling and earth escaping are more clearly pronounced in the vocabulary of architectural planning and design  . Many of us had percept the positive effect in underground tunnels by traveling through the metro. The vital and efficient sustainable energy which can be used by us is underground thermal inertia; we can become aware of that, the earth can serve in many climates as a heating or cooling source. Its high thermal capacity keeps the soil temperature, below a certain depth, considerably lower than the ambient air temperature during summer and higher than the ambient air temperature during winter. Seasonal variation of the earth temperature decreases with increase of depth, moisture content of soil and soil conductivity. It is estimated that a small number of meters below the earth surface, the earth temperature remains constant during the year. In regions with temperate climate such as Denmark, the temperature of the soil at depth of 2-3 meters can be low enough during summer or high enough during winter, to serve as a cooling or heating source. Using of the underground constant temperature can be useful for architects and designer because the temperature is between 8ºC-13ºC, and2- 3 m above the earth, can help us to find a competent solution which help us to controlled thermal comfort in houses.

  • 3748.
    Zanden Kjellen, Peder
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013).
    Investigating the impact on marginal prices when using an increasing block tariff: An economic tool to reduce peak flowrates atwastewater treatment facilities2016Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    In wastewater management big variations in flowrates, caused by precipitation, leads to high peak loads forcing treatment facilities to maintain large over capacity. Wastewater management is a capital-intensive industry, meaning that new investments are costly and should therefore be avoided. But as peak load levels increase and stricter regulations are imposed it becomes increasingly hard to maintain sufficient reduction rates and facilities are likely to face new investments if the highest flowrates can’t be reduced. One way to reduce flowrates is to charge higher prices for the peak loads through an efficient tariff design.

    This thesis includes a literature review to define what constitutes an efficient tariff and then moves on to develop a model including marginal cost pricing and increasing block tariff design that examine how the marginal cost price is affected by constructing the tariff in different ways.

    The results show that the marginal price can be significantly increased by adapting this approach compared to a two part tariff with one fixed and one variable part which is commonly used by wastewater utilities today. The biggest deciding factor will be how the marginal block is defined.

  • 3749.
    Zanganeh, Arjan
    Karlstads universitet, Fakulteten för teknik- och naturvetenskap.
    Lyftanordningsbeskrivning för Metso Fiber AB2013Självständigt arbete på grundnivå (högskoleexamen), 15 poäng / 22,5 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Examensarbetet är utfört på Metso Fiber i Karlstad som tillhör koncernen Metso coperation. Företaget är en global leverantör av teknik och tjänster för gruvdrifts, markbyggnads, energiproduktions, automations, återvinnings samt massa och pappersindustrin.

    Metso Fiber AB har ett behov att se över lyft och transportritningar för alla deras maskiner. Dock har examensarbetet begränsats till två stycken maskiner där var och en av maskinerna har flera olika storlekar De maskiner som jag har granskat är flismätaren och utloppsanordningen.

    För att kunna lösa uppgiften korrekt krävs det förståelse för hur maskinerna är uppbyggda. Man ska även förstå hur montage och demontering fungerar och därmed behöver kontakt etableras med olika delar av företaget. I uppgiften ingår även konstruktion och beräkning av eventuella lyftöron/öglor samt bestämma var lyftöron/öglor bör placeras och vilket material som bör väljas. Likaså krävs förståelse för maskinerna som är känsliga för yttre krafter. Målet med examensarbetet är att ta fram en procedur för hur ett lyft till rätt position bör göras.

    Efter många diskussioner och försök kom vi fram till en rimlig FEM-analys och en lämplig lyftbeskrivning. Lyftbeskrivningen ska bestå av tydliga vyer av maskinen, 2D och 3D vyer samt den relevanta informationen som gäller för de specifika maskinerna, i form av tabeller.

     

  • 3750.
    Zappine, M
    et al.
    Politecnico di Torino, Italy.
    Fiore, S
    Politecnico di Torino, Italy.
    Govindarajan, Venkatesh
    Brattebö, L
    V.
    Meucci, L
    Research Center, Torino, Italy.
    Life-cycle energy and greenhouse gas emissions within the Turin Metropolitan Urban Water Cycle2014Ingår i: Procedia Engineering, ISSN 1877-7058, E-ISSN 1877-7058, Vol. 89, nr 1, s. 1382-1389Artikel i tidskrift (Refereegranskat)
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