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  • 2951. Akabori, M.
    et al.
    Hidaka, S.
    Iwase, H.
    Yamada, S.
    Ekenberg, Ulf
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Realization of In0.75Ga0.25As two-dimensional electron gas bilayer system for spintronics devices based on Rashba spin-orbit interaction2012In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 112, no 11, p. 113711-Article in journal (Refereed)
    Abstract [en]

    Narrow gap InGaAs two-dimensional electron gas (2DEG) bilayer samples are fabricated and confirmed to have good electronic qualities as well as strong Rashba-type spin-orbit interactions (SOIs). The 2DEG systems are realized by molecular beam epitaxy in the form of wide quantum wells (QWs) with thicknesses tQW∼40-120nm modulation doped in both the upper and lower InAlAs barriers. From the Hall measurements, the overall mobility values of μe ∼15 m2/V s are found for the total sheet electron density of ns ∼8 × 1011/cm2, although the ns is distributed asymmetrically as about 1:3 in the upper and lower 2DEGs, respectively. Careful low temperature magneto-resistance analysis gives large SO coupling constants of α ∼20 × 10 -12eV m as well as expected electron effective masses of m*/m0 ∼0.033-0.042 for each bilayer 2DEG spin sub-band. Moreover, the enhancement of α with decrease of tQW is found. The corresponding self-consistent calculation, which suggests the interaction between the bilayer 2DEGs, is carried out and the origin of α enhancement is discussed.

  • 2952.
    Akan, Pelin
    et al.
    KTH, School of Biotechnology (BIO), Gene Technology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Alexeyenko, Andrey
    KTH, School of Biotechnology (BIO), Gene Technology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Costea, Paul Igor
    KTH, School of Biotechnology (BIO), Gene Technology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Hedberg, Lilia
    KTH, School of Biotechnology (BIO), Gene Technology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Werne Solnestam, Beata
    KTH, School of Biotechnology (BIO), Gene Technology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Lundin, Sverker
    KTH, School of Biotechnology (BIO), Gene Technology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Hallman, Jimmie
    Lundberg, Emma
    KTH, School of Biotechnology (BIO), Gene Technology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Uhlén, Mathias
    KTH, School of Biotechnology (BIO), Proteomics (closed 20130101). KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Lundeberg, Joakim
    KTH, School of Biotechnology (BIO), Gene Technology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Comprehensive analysis of the genome transcriptome and proteome landscapes of three tumor cell lines2012In: Genome Medicine, ISSN 1756-994X, E-ISSN 1756-994X, Vol. 4, p. 86-Article in journal (Refereed)
    Abstract [en]

    We here present a comparative genome, transcriptome and functional network analysis of three human cancer cell lines (A431, U251MG and U2OS), and investigate their relation to protein expression. Gene copy numbers significantly influenced corresponding transcript levels; their effect on protein levels was less pronounced. We focused on genes with altered mRNA and/or protein levels to identify those active in tumor maintenance. We provide comprehensive information for the three genomes and demonstrate the advantage of integrative analysis for identifying tumor-related genes amidst numerous background mutations by relating genomic variation to expression/protein abundance data and use gene networks to reveal implicated pathways.

  • 2953.
    Akan, Pelin
    et al.
    KTH, Centres, Science for Life Laboratory, SciLifeLab. KTH, School of Biotechnology (BIO).
    Stranneheim, Henrik
    KTH, Centres, Science for Life Laboratory, SciLifeLab. KTH, School of Biotechnology (BIO).
    Lexow, Preben
    LingVitae, Oslo.
    Lundeberg, Joakim
    KTH, Centres, Science for Life Laboratory, SciLifeLab. KTH, School of Biotechnology (BIO).
    Design and assessment of binary DNA for nanopore sequencing2010In: Genome biology, ISSN 1474-760X, Vol. 11, p. P4-Article in journal (Other academic)
  • 2954.
    Akan, Rabia
    KTH, School of Chemical Science and Engineering (CHE).
    Oorganiska-organiska nanopartikelbaserade supramolekylära strukturer för biomedicinska applikationer2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The possibility to create a multifunctional nanoparticle system via supramolecular chemistry approach with ability to simultaneously target, deliver and diagnose was investigated. Superparamagnetic iron oxide nanoparticles were synthesized by co-precipitation method and surface modified with the cyclic oligosaccharide carboxymethyl-β-cyclodextrin by three different routes. The different routes involved one, two or three reaction steps in order to reach to the final oligosaccharide functionalized nanoparticles. Esterification was performed using the intrinsic hydroxyl functionality of the nanoparticle surfaces or amine functionality was introduced prior to amidization. Further, a polymeric coating was created by incorporation of folic acid functionalized Pluronic® L-35 into carboxymethyl-β-cyclodextrin. The resulting nanoparticle based supramolecular systems were characterized by TEM, TGA, FT-IR, DLS and zeta potential techniques.

     

    The colloidal stabilities of the supramolecular nanoparticle systems were investigated in phosphate buffered saline with pH 7.4 representing body conditions. It was found that a three-step functionalization of iron oxide nanoparticles with citric acid, hexamethylenediamine and finally carboxymethyl-β-cyclodextrin resulted in the most stable ferrofluids. The average size of the resulting carboxymethyl-β-cyclodextrin functionalized nanoparticles was 25 nm prior to, and 50 nm after inclusion of folic acid functionalized Pluronic. The amount of grafted carboxymethyl-β-cyclodextrin on the nanoparticles surfaces was 25 weight %. Thus, the resulting stable ferrofluid creates an efficient platform with potential of multiple uses in biomedicine. This nanoparticle based supramolecular system combines the properties of magnetic targeting and MRI contrast enhancement due to the superparamagnetic iron oxide nanoparticle core, drug delivery of hydrophobic drugs due to the polymer capsule and selective targeting towards tumour cells due to the folic acid.

  • 2955.
    Akan, Rabia
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Parfeniukas, Karolis
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Vogt, Carmen
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Toprak, M. S.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Vogt, Ulrich
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Reaction control of metal-assisted chemical etching for silicon-based zone plate nanostructures2018In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 8, no 23, p. 12628-12634Article in journal (Refereed)
    Abstract [en]

    Metal-assisted chemical etching (MACE) reaction parameters were investigated for the fabrication of specially designed silicon-based X-ray zone plate nanostructures using a gold catalyst pattern and etching solutions composed of HF and H2O2. Etching depth, zone verticality and zone roughness were studied as a function of etching solution composition, temperature and processing time. Homogeneous, vertical etching with increasing depth is observed at increasing H2O2 concentrations and elevated processing temperatures, implying a balance in the hole injection and silica dissolution kinetics at the gold-silicon interface. The etching depth decreases and zone roughness increases at the highest investigated H2O2 concentration and temperature. Possible reasons for these observations are discussed based on reaction chemistry and zone plate design. Optimum MACE conditions are found at HFH2O2 concentrations of 4.7 M:0.68 M and room temperature with an etching rate of ≈0.7 μm min-1, which is about an order of magnitude higher than previous reports. Moreover, our results show that a grid catalyst design is important for successful fabrication of vertical high aspect ratio silicon nanostructures. 

  • 2956.
    Akan, Rabia
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Parfeniukas, Karolis
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics. KTH Royal Institute of Technology.
    Vogt, Carmen
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Toprak, Muhammet S.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Vogt, Ulrich
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Reaction control of metal-assisted chemical etching for silicon-based zone plate nanostructuresManuscript (preprint) (Other academic)
    Abstract [en]

    Metal-assisted chemical etching (MACE) reaction parameters were investigated for the fabrication of specially designed silicon-based x-ray zone plate nanostructures using a gold catalyst pattern and etching solutions composed of HF and H2O2. Etching depth, zone verticality and zone roughness were studied as a function of etching solution composition, temperature and processing time. Homogeneous, vertical etching with increasing depth is observed at increasing H2O2 concentrations and elevated processing temperatures, implying a balance in the hole injection and silica dissolution kinetics at the gold-silicon interface. The etching depth decreases and zone roughness increases at the highest investigated H2O2 concentration and temperature. Possible reasons for these observations are discussed based on reaction chemistry and zone plate design. Optimum MACE conditions are found at HF:H2O2 concentrations of 4.7 M:0.68 M and room temperature with an etching rate of 0.7 micrometers per minute, which is about an order of magnitude higher than previous reports. Moreover, our results show that a grid catalyst design is important for successful fabrication of vertical high aspect ratio silicon nanostructures.

  • 2957.
    Akander, Amanda
    KTH, School of Biotechnology (BIO).
    Development and Evaluation of a Lateral Flow Immunoassay for on-site Diagnosisof Contagious Bovine Pleuropneumonia2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The purpose of this study was to develop and evaluate a lateral flow immunoassay, as a point-of-care prototype for diagnosis of contagious bovine pleuropneumonia (CBPP). The assay was based on a panel of recombinant proteins spotted on a nitrocellulose membrane. The study included optimization of assay components, such as running buffer and protein microarray layout. The purpose was to obtain a clear discriminatory capacity between CBPP positive and CBPP negative sera, by developing and evaluating a lateral flow immunoassay that could be used on-site.

    The discriminatory capacity between CBPP positive sera and CBPP negative sera in the lateral flow assay was statistically significant with p-values ≤0.05 for recombinant proteins to be printed in microarray spots both individually as well as proteins printed as mixtures. The sensitivity of the assay was 64% and the specificity 100%, which was comparable to current diagnostic methods for CBPP. From these rsults, four combinations of recombinant proteins were selected to print as a microarray, which was based on p-valuesas well as sera coverage. As the purpose of this study was to develop a prototype for on-site usage, a fieldtrip to Nairobi, Kenya, facilitated by the Swedish International Development Cooperation Agency, SIDA, was made to test the prototpyes as well as obtain deeper knowledge of user area. However, the lateral flow immunoassay did not deliver reproducible and stable results during the field trip to Kenya.

  • 2958.
    Akander, Amanda
    KTH, School of Biotechnology (BIO).
    Massive parallell DNA-sequencing - future methods to obtain a human genome in 15 minutes2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 2959.
    Akander, Jan
    KTH, Superseded Departments, Building Sciences and Engineering.
    The ORC method2000Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    The ORC Method (Optimised RC-networks) provides a means ofmodelling one- or multidimensional heat transfer in buildingcomponents, in this context within building simulationenvironments. The methodology is shown, primarily applied toheat transfer in multilayer building components. For multilayerbuilding components, the analytical thermal performance isknown, given layer thickness and material properties. The aimof the ORC Method is to optimise the values of the thermalresistances and heat capacities of an RC-model such as to givemodel performance a good agreement with the analyticalperformance, for a wide range of frequencies. The optimisationprocedure is made in the frequency domain, where the over-alldeviation between model and analytical frequency response, interms of admittance and dynamic transmittance, is minimised. Itis shown that ORC's are effective in terms of accuracy andcomputational time in comparison to finite difference modelswhen used in building simulations, in this case with IDA/ICE.An ORC configuration of five mass nodes has been found to modelbuilding components in Nordic countries well, within theapplication of thermal comfort and energy requirementsimulations.

    Simple RC-networks, such as the surface heat capacity andthe simple R-C-configuration are not appropriate for detailedbuilding simulation. However, these can be used as basis fordefining the effective heat capacity of a building component.An approximate method is suggested on how to determine theeffective heat capacity without the use of complex numbers.This entity can be calculated on basis of layer thickness andmaterial properties with the help of two time constants. Theapproximate method can give inaccuracies corresponding to20%.

    In-situ measurements have been carried out in anexperimental building with the purpose of establishing theeffective heat capacity of external building components thatare subjected to normal thermal conditions. The auxiliary wallmethod was practised and the building was subjected toexcitation with radiators. In a comparison, there werediscrepancies between analytical and measured effective heatcapacities. It was found that high-frequency discrepancies wereto a large extent caused by the heat flux sensors.Low-frequency discrepancies are explained by the fact that theexterior climate contained other frequencies than those assumedin the interior climate.

    Key words: Building component, building simulation, heattransfer, thermal performance, frequency response, RC-network,finite difference model.

  • 2960.
    Akander, Jan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Alvarez, S
    Jóhannesson, Gundi
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Energy normalization techniques2004In: Energy Performance of Residential Buildings: A Practical Guide for Energy Rating and Efficiency, James & James/Earthscan , 2004, p. 57-70Chapter in book (Other academic)
  • 2961.
    Akander, Jan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Jóhnnesson, Gudini
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Experimental methods for the energy characterization of buildings2004In: Energy Performance of Residential Buildings: A Practical Guide for Energy Rating and Efficiency, James & James/Earthscan , 2004, p. 26-56Chapter in book (Other academic)
  • 2962.
    Akay, Altug
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    A Novel Method to Intelligently Mine Social Media to Assess Consumer Sentiment of Pharmaceutical Drugs2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis focuses on the development of novel data mining techniques that convert user interactions in social media networks into readable data that would benefit users, companies, and governments. The readable data can either warn of dangerous side effects of pharmaceutical drugs or improve intervention strategies. A weighted model enabled us to represent user activity in the network, that allowed us to reflect user sentiment of a pharmaceutical drug and/or service. The result is an accurate representation of user sentiment. This approach, when modified for specific diseases, drugs, and services, can enable rapid user feedback that can be converted into rapid responses from consumers to industry and government to withdraw possibly dangerous drugs and services from the market or improve said drugs and services.

    Our approach monitors social media networks in real-time, enabling government and industry to rapidly respond to consumer sentiment of pharmaceutical drugs and services.

  • 2963.
    Akay, Altug
    et al.
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    Dragomir, A.
    Department of Biomedical Engineering, University of Houston, Houston, TX, US.
    Erlandsson, Björn-Erik
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    A novel data-mining approach leveraging social media to monitor and respond to outcomes of diabetes drugs and treatment2013In: 2013 IEEE Point-of-Care Healthcare Technologies (PHT), New York: IEEE , 2013, p. 264-266Conference paper (Refereed)
    Abstract [en]

    A novel data-mining method was developed to gauge the experiences of medical devices and drugs by patients with diabetes mellitus. Self-organizing maps were used to analyze forum posts numerically to better understand user opinion of medical devices and drugs. The end-result is a word list compilation that correlates certain positive and negative word cluster groups with medical drugs and devices. The implication of this novel data-mining method could open new avenues of research into rapid data collection, feedback, and analysis that would enable improved outcomes and solutions for public health.

  • 2964.
    Akay, Altug
    et al.
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    Dragomir, A
    Erlandsson, Björn-Erik
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    A Novel Data-Mining Approach Leveraging Social Media to Monitor Consumer Opinion of Sitagliptin2015In: IEEE journal of biomedical and health informatics, ISSN 2168-2194, E-ISSN 2168-2208, Vol. 19, no 1, p. 389-396Article in journal (Refereed)
    Abstract [en]

    A novel data mining method was developed to gauge the experience of the drug Sitagliptin (trade name Januvia) by patients with diabetes mellitus type 2. To this goal, we devised a two-step analysis framework. Initial exploratory analysis using self-organizing maps was performed to determine structures based on user opinions among the forum posts. The results were a compilation of user's clusters and their correlated (positive or negative) opinion of the drug. Subsequent modeling using network analysis methods was used to determine influential users among the forum members. These findings can open new avenues of research into rapid data collection, feedback, and analysis that can enable improved outcomes and solutions for public health and important feedback for the manufacturer.

  • 2965.
    Akay, Altug
    et al.
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    Dragomir, A.
    Erlandsson, Björn-Erik
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    A novel data-mining platform leveraging social media to monitor outcomes of Januvia2013In: Engineering in Medicine and Biology Society (EMBC), 2013 35th Annual International Conference of the IEEE, IEEE conference proceedings, 2013, p. 7484-7487Conference paper (Refereed)
    Abstract [en]

    A novel data-mining method was developed to gauge the experiences of the diabetes mellitus drug Januvia. Self-organizing maps were used to analyze forum posts numerically to infer user opinion of drug Januvia. Graph theory was used to discover influential users. The result is a word list compilation correlating positive and negative word cluster groups and a web of influential users on Januvia. The implications could open new research avenues into rapid data collection, feedback, and analysis that would enable improved solutions for public health.

  • 2966.
    Akay, Altug
    et al.
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    Dragomir, A
    Erlandsson, Björn-Erik
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    Network-Based Modeling and Intelligent Data Mining of Social Media for Improving Care2015In: IEEE journal of biomedical and health informatics, ISSN 2168-2194, E-ISSN 2168-2208, Vol. 19, no 1, p. 210-218Article in journal (Refereed)
    Abstract [en]

    Intelligently extracting knowledge from social media has recently attracted great interest from the Biomedical and Health Informatics community to simultaneously improve healthcare outcomes and reduce costs using consumer-generated opinion. We propose a two-step analysis framework that focuses on positive and negative sentiment, as well as the side effects of treatment, in users' forum posts, and identifies user communities (modules) and influential users for the purpose of ascertaining user opinion of cancer treatment. We used a self-organizing map to analyze word frequency data derived from users' forum posts. We then introduced a novel network-based approach for modeling users' forum interactions and employed a network partitioning method based on optimizing a stability quality measure. This allowed us to determine consumer opinion and identify influential users within the retrieved modules using information derived from both word-frequency data and network-based properties. Our approach can expand research into intelligently mining social media data for consumer opinion of various treatments to provide rapid, up-to-date information for the pharmaceutical industry, hospitals, and medical staff, on the effectiveness (or ineffectiveness) of future treatments.

  • 2967.
    Akay, Altug
    et al.
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    Dragomir, Andrei
    Erlandsson, Björn-Erik
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    A Novel-Data Mining Platform to Monitor the Outcomes of Erlontinib (Tarceva) using Social Media2014In: XIII Mediterranean Conference on Medical and Biological Engineering and Computing 2013, Springer, 2014, p. 1394-1397Conference paper (Refereed)
    Abstract [en]

    A novel data-mining method was developed to gauge the experiences of the oncology drug Tarceva. Self-organizing maps were used to analyze forum posts numerically to infer user opinion of drug Tarceva. The result is a word list compilation correlating positive and negative word cluster groups and a web of influential users on Tarceva. The implica-tions could open new research avenues into rapid data collec-tion, feedback, and analysis that would enable improved solu-tions for public health.

  • 2968.
    Akay, Altug
    et al.
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    Dragomir, Andrei
    Erlandsson, Björn-Erik
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    Assessing Antidepressants Using Intelligent Data Monitoring and Mining of Online Fora2016In: IEEE journal of biomedical and health informatics, ISSN 2168-2194, E-ISSN 2168-2208, Vol. 20, no 4, p. 977-986Article in journal (Refereed)
    Abstract [en]

    Depression is a global health concern. Social networks allow the affected population to share their experiences. These experiences, when mined, extracted, and analyzed, can be converted into either warnings to recall drugs (dangerous side effects), or service improvement (interventions, treatment options) based on observations derived from user behavior in depression-related social networks. Our aim was to develop a weighted network model to represent user activity on social health networks. This enabled us to accurately represent user interactions by relying on the data's semantic content. Our three-step method uses the weighted network model to represent user's activity, and network clustering and module analysis to characterize user interactions and extract further knowledge from user's posts. The network's topological properties reflect user activity such as posts' general topic as well as timing, while weighted edges reflect the posts semantic content and similarities among posts. The result, a synthesis from word data frequency, statistical analysis of module content, and the modeled health network's properties, has allowed us to gain insight into consumer sentiment of antidepressants. This approach will allow all parties to participate in improving future health solutions of patients suffering from depression.

  • 2969.
    Akay, Altug
    et al.
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    Dragomir, Andrei
    University of Houston, Biomedical Engineering.
    Erlandsson, Björn-Erik
    KTH, School of Technology and Health (STH), Health Systems Engineering.
    Mining Social Media Big Data for Health2015In: IEEE PulseArticle, review/survey (Refereed)
    Abstract [en]

    Advances in information technology (IT) and big data are affecting nearly every facet of the public and private sectors. Social media platforms are one example of such advances: its nature allows users to connect, collaborate, and debate on any topic with comparative ease. The result is a hefty volume of user-generated content that, if properly mined and analyzed, could help the public and private health care sectors improve the quality of their products and services while reducing costs. The users of these platforms are the key to these improvements, as their valuable feedback will help improve health solutions.

  • 2970. Akbar, F.
    et al.
    Kolahdouz, M.
    Larimian, Sh.
    Radfar, B.
    Radamson, Henry
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Graphene synthesis, characterization and its applications in nanophotonics, nanoelectronics, and nanosensing2015In: Journal of materials science. Materials in electronics, ISSN 0957-4522, E-ISSN 1573-482X, Vol. 26, no 7, p. 4347-4379Article in journal (Refereed)
    Abstract [en]

    In the last decade, as semiconductor industry was approaching the end of the exponential Moore's roadmap for device downscaling, the necessity of finding new candidate materials has forced many research groups to explore many different types of non-conventional materials. Among them, graphene, CNTs and organic conductors are the most successful alternatives. Finding a material with metallic properties combined with field effect characteristics on nanoscale level has been always a dream to continue the ever-shrinking road of the nanoelectronics. Due to its fantastic features such as high mobility, optical transparency, room temperature quantum Hall effect, mechanical stiffness, etc. the atomically thin carbon layer, graphene, has attracted the industry's attention not only in the micro-, nano-, and opto-electronics but also in biotechnology. This paper reviews the basics and previous works on graphene technology and its developments. Compatibility of this material with Si processing technology is its crucial characteristic for mass production. This study also reviews the physical and electrical properties of graphene as a building block for other carbon allotropes. Different growth methods and a wide range of graphene's applications will be discussed and compared. A brief comparison on the performance result of different types of devices has also been presented. Until now, the main focus of research has been on the background physics and its application in electronic devices. But, according to the recent works on its applications in photonics and optoelectronics, where it benefits from the combination of its unique optical and electronic properties, even without a bandgap, this material enables ultrawide-band tunability. Here in this article we review different applications and graphene's advantages and drawbacks will be mentioned to conclude at the end.

  • 2971.
    AKBARI KHALIL ABAD, HANNANE
    et al.
    KTH, School of Chemical Science and Engineering (CHE).
    ARONSSON, JENS
    KTH, School of Chemical Science and Engineering (CHE).
    PERSSON, ALEXANDER
    KTH, School of Chemical Science and Engineering (CHE).
    REINECK POPA, ERIK
    KTH, School of Chemical Science and Engineering (CHE).
    Heterogen katalys för produktion av biodiesel från rester av matolja2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Energikonsumtionen inom transportsektor består till störst del av konsumtion av fossila bränslen. Transportsektorn själv står för ca 30 % av världens totala energikonsumtion. Att växla till ett grönt drivmedel skulle bidra till en mer ekologiskt hållbar verksamhet.

    Biodiesel kan vara svaret på transportsektorns problem och kan dessutom framställas av vad man idag anser är avfall. Restmatolja kan med hjälp av katalysatorer transesterifieras till biodiesel som efter inblandning av konventionell diesel kan köras i dagens dieselmotorer.

    För att spara resurser är en process med heterogen katalysator bättre än en homogen process. I rapporten undersöks om MgO, CaO och Li2O kan användas som katalysator för att framställa biodieseln från restmatoljan. Studien undersöker också om SnO eller SnO2 kan tillsättas till katalysatorn för att öka utbytet.

    Försök genomfördes i labbmiljö med restolja från en lokal restaurang. Olika parametrar testades för att optimera utbytet. Parametrarna som ändrades var temperatur, mängd katalysator och molförhållandet mellan alkohol och olja. Varje parameter varierades mellan två värden.

    Resultaten visade att CaO var den enda av de undersökta katalysatorerna som fungerade och gav ett tillräckligt bra utbyte. SnO som användes tillsammans med CaO visade en liten effekt av att öka utbytet, men antalet försök var för få för att kunna dra några säkra slutsatser.

    Resultaten från undersökningen av optimala parametrar visar att utbytet minskar med ökande temperatur. Större andel alkohol jämfört med olja ger ett högre utbyte. Med ökande mängd katalysator finns ett optimalt värde och när det överskrids minskar utbytet igen.

    Vidare studier krävs för att optimera de heterogena katalysatorerna i biodieselframställningen.

  • 2972. Akbari, N.
    et al.
    Modarressi, M.
    Daneshtalab, Masoud
    KTH.
    Loni, Efisio
    KTH.
    A Customized Processing-in-Memory Architecture for Biological Sequence Alignment2018In: Proceedings of the International Conference on Application-Specific Systems, Architectures and Processors, Institute of Electrical and Electronics Engineers Inc. , 2018, Vol. 2018, article id 8445124Conference paper (Refereed)
    Abstract [en]

    Sequence alignment is the most widely used operation in bioinformatics. With the exponential growth of the biological sequence databases, searching a database to find the optimal alignment for a query sequence (that can be at the order of hundreds of millions of characters long) would require excessive processing power and memory bandwidth. Sequence alignment algorithms can potentially benefit from the processing power of massive parallel processors due their simple arithmetic operations, coupled with the inherent fine-grained and coarse-grained parallelism that they exhibit. However, the limited memory bandwidth in conventional computing systems prevents exploiting the maximum achievable speedup. In this paper, we propose a processing-in-memory architecture as a viable solution for the excessive memory bandwidth demand of bioinformatics applications. The design is composed of a set of simple and lightweight processing elements, customized to the sequence alignment algorithm, integrated at the logic layer of an emerging 3D DRAM architecture. Experimental results show that the proposed architecture results in up to 2.4x speedup and 41% reduction in power consumption, compared to a processor-side parallel implementation.

  • 2973.
    Akbaripour Sheijnai, Solmaz
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Numerical studies on receptivity and control of a three-dimensional boundary layer2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Receptivity in three-dimensional boundary layer ow to localized roughness elements over a at plate is studied by means of direct numerical simulations (DNS). The surface roughness is modeled by applying nonhomogeneous boundary conditions along the wall as well as considering as a surface deformation by inserting the bump shape into the numerical mesh. Under the assumption of the small amplitudes of the roughness, although dierent disturbances amplitudes are observed in the vicinity of the bump for the meshed and modeled case, the boundary layer response downstream of the roughness is independent if the way of the bump implementation. Dierent roughness heights are considered in order to compare the boundary layer response of two approaches. Also, the boundary layer is excited by random distributed surface roughness and the receptivity results are studied. Moreover, a simple model for natural roughness excites steady multi wavenumber crossow instabilities. A localised surface roughness i.e. control roughness is applied to stabilise the latter. The control mode which is subcritical with respect to transition aects the most steady unstable mode. Suppression of the most dangerous mode is observed through nonlinear interactions with the control mode.

  • 2974.
    Akbarnejad, Shahin
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Experimental and Mathematical Study of Incompressible Fluid Flow through Ceramic Foam Filters2016Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Ceramic Foam Filters (CFFs) are widely used to filter solid particles and inclusions from molten metal in metal production, particularly in the aluminum industry. In general, the molten metal is poured on the top of a ceramic foam filter until it reaches a certain height, also known as metal head or gravity head. This is done to build the required pressure to prime the filter media and to initiate filtration. To predict the required metal head, it is necessary to obtain the Darcy and non-Darcy permeability coefficients of the filter. The coefficients vary upon filter type. Here, it is common to classify CFFs based on grades or pore per inches (PPI). These CFFs range from10 to100 PPI and their properties vary in everything from cell and window size to strut size. The 80-100 PPI CFFs are generally not practical for use by industry, since the priming of the filters by a gravitational force requires an excessive metal head. However, recently a new method has been developed to prime such filters by using electromagnetic Lorentz forces. This allows the filters to be primed at a low metal head.

    To continue the research work, it was deemed necessary to measure the pressure gradients of single and stack of commercial alumina ceramic foam filters and to obtain the permeability characteristics. Therefore, efforts have been made to validate the previously obtained results, to improve the permeametry experimental setup, and to obtain Darcy and non-Darcy permeability coefficients of single 30, 50, and 80 PPI filters and stacks of filters. Furthermore, the experimentally obtained pressure gradients were analyzed and compered to the mathematically and analytically estimated pressure gradients.

    The studies showed that, in permeametry experiments, the sample sealing procedure plays an important role for an accurate estimation of the permeability constants. An inadequate sealing or an un-sealed sample results in an underestimation of the pressure drop, which causes a considerable error in the obtained Darcy and non-Darcy permeability coefficients. Meanwhile, the results from the single filter experiments showed that the permeability values of the similar PPI filters are not identical. However, the stacks of three identical filters gave substantially the same measured pressure drop values and roughly the same Darcy and non-Darcy coefficients as for the single filters.

    The permeability coefficients of the filters are believed to be best defined and calculated by using the Forchheimer equation. The well-known and widely used Ergun and Dietrich equations cannot correctly predict the pressure drop unless a correction factor is introduced. The accuracy of the mathematically estimated pressure drop, using COMSOL Multiphysics® 5.1, found to be dependent on the drag term used in the Brinkman-Forchheimer equation.  Unacceptable error, as high as 84 to 89 percent for the 30, 50 and 80 PPI single filters, compared to the experimentally obtained pressure gradient values were observed when the literature defined Brinkman-Forchheimer drag term was used. However, when the same second order drag term (containing the non-Darcy coefficient) as defined in the Forchheimer equation was used, the predicted pressure gradient profiles satisfactorily agreed with the experiment data with as little as 0.3 to 5.5 percent deviations for the 30, 50 and 80 PPI single filters.

  • 2975.
    Akbarnejad, Shahin
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Investigation on static strength of welded joints2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Although high strength steels represent yield strength up to 1300 MPa, welded structures reveal lowerstrength values. The strongest commercially available electrode provides the yield strength of about900 MPa. Therefore, in welded steels with strength above this type of filler metal, achieving anacceptable global strength is a crucial issue.

    In this master thesis, affects of different welding procedures on static strength of welded jointsof Weldox 960 and Weldox 1100 steels, were studied. These steels are produced by SSAB inOxelösund. Meanwhile, finite element method analyses were applied in order to investigatethe static strength behavior of such weldments under uniaxial tension.

    The welding parameters which were selected as variables are:

    •  Heat input
    • Weld joint geometry
    • Filler metal

    When weld metal is undermatching in strength levels than the base material, by applyingtension the soft weld metal begins to deform before parent metal. At that point thedeformation of resulted soft zone, including the weld metal and the heat affected zone, ishindered by high strength parent metal. Thus, uniaxial stress caused by uniaxial load isconverted to multiaxial stress. This conversion in tension results in increase in the staticstrength of weldment. The increase in strength is emphasized by increase in the width of thewelded joint while the thickness of the plate is kept as constant.

    After experiments and performing FEM studies, it was revealed that the static strength ofWeldox 960 welded joints approaches towards the tensile strength of parent metal by increasein the width of the weldment. In Weldox 1100 joints; a slight increase in tensile properties ofthe weldments, when the width of the sample increases, was observed.

  • 2976.
    Akbarnejad, Shahin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jonsson, Lage
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Kennedy, M. W.
    Aune, R. E.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Analysis on Experimental Investigation and Mathematical Modelling of Incompressible Flow through Ceramic Foam FiltersManuscript (preprint) (Other academic)
  • 2977.
    Akbarnejad, Shahin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Jonsson, Lage Tord Ingemar
    Kennedy, Mark William
    Aune, Ragnhild Elizabeth
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Analysis on Experimental Investigation and Mathematical Modeling of Incompressible Flow Through Ceramic Foam Filters2016In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 47, no 4, p. 2229-2243Article in journal (Refereed)
    Abstract [en]

    This paper presents experimental results of pressure drop measurements on 30, 50, and 80 pores per inch (PPI) commercial alumina ceramic foam filters (CFF) and compares the obtained pressure drop profiles to numerically modeled values. In addition, it is aimed at investigating the adequacy of the mathematical correlations used in the analytical and the computational fluid dynamics (CFD) simulations. It is shown that the widely used correlations for predicting pressure drop in porous media continuously under-predict the experimentally obtained pressure drop profiles. For analytical predictions, the negative deviations from the experimentally obtained pressure drop using the unmodified Ergun and Dietrich equations could be as high as 95 and 74 pct, respectively. For the CFD predictions, the deviation to experimental results is in the range of 84.3 to 88.5 pct depending on filter PPI. Better results can be achieved by applying the Forchheimer second-order drag term instead of the Brinkman-Forchheimer drag term. Thus, the final deviation of the CFD model estimates lie in the range of 0.3 to 5.5 pct compared to the measured values.

  • 2978.
    Akbarnejad, Shahin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Kennedy, M. W.
    Fritzsch, R.
    Aune, R. E.
    An investigation on permeability of ceramic foam filters (CFF)2015In: TMS Light Metals, 2015, p. 949-954Conference paper (Refereed)
    Abstract [en]

    CFFs are used to filter liquid metal in the aluminum industry. CFFs are classified in grades or pores per inch (PPI), ranging from 10-100 PPI. Their properties vary in everything from pore and strut size to window size. CFFs of 80-100 PPI are generally not practical for use by industry, as priming of the filters by gravitational forces requires an excessive metal head. Recently, co-authors have invented a method to prime such filters using electromagnetic Lorentz forces, thus allowing filters to be primed with a low metal head. In the continuation of this research work, an improved experimental setup was developed in the present study to validate previous results and to measure the permeability of different filters, as well as a stack of filters. The study of permeability facilitates estimation of the required pressure drop to prime the filters and the head required to generate a given casting rate.

  • 2979.
    Akbarnejad, Shahin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Saffari Pour, Mohsen
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jonsson, Lage
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Significance of Fluid Bypassing Effect on Darcy and Non-Darcy Permeability Parameters of Ceramic Foam FiltersManuscript (preprint) (Other academic)
  • 2980.
    Akbarnejad, Shahin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Saffari Pour, Mohsen
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Jonsson, Lage Tord Ingemar
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Jönsson, Pӓr Göran
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Effect of Fluid Bypassing on the Experimentally Obtained Darcy and Non-Darcy Permeability Parameters of Ceramic Foam Filters2017In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 48, no 1, p. 197-207Article in journal (Refereed)
    Abstract [en]

    Ceramic foam filters (CFFs) are used to remove solid particles and inclusions from molten metal. In general, molten metal which is poured on the top of a CFF needs to reach a certain height to build the required pressure (metal head) to prime the filter. To estimate the required metal head, it is necessary to obtain permeability coefficients using permeametry experiments. It has been mentioned in the literature that to avoid fluid bypassing, during permeametry, samples need to be sealed. However, the effect of fluid bypassing on the experimentally obtained pressure gradients seems not to be explored. Therefore, in this research, the focus was on studying the effect of fluid bypassing on the experimentally obtained pressure gradients as well as the empirically obtained Darcy and non-Darcy permeability coefficients. Specifically, the aim of the research was to investigate the effect of fluid bypassing on the liquid permeability of 30, 50, and 80 pores per inch (PPI) commercial alumina CFFs. In addition, the experimental data were compared to the numerically modeled findings. Both studies showed that no sealing results in extremely poor estimates of the pressure gradients and Darcy and non-Darcy permeability coefficients for all studied filters. The average deviations between the pressure gradients of the sealed and unsealed 30, 50, and 80 PPI samples were calculated to be 57.2, 56.8, and 61.3 pct. The deviations between the Darcy coefficients of the sealed and unsealed 30, 50, and 80 PPI samples found to be 9, 20, and 31 pct. The deviations between the non-Darcy coefficients of the sealed and unsealed 30, 50, and 80 PPI samples were calculated to be 59, 58, and 63 pct.

  • 2981.
    Akbarpour, S.
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Hallström, S.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Metal reinforcement around fastener holes in composites2016In: ECCM 2016 - Proceeding of the 17th European Conference on Composite Materials, European Conference on Composite Materials, ECCM , 2016Conference paper (Refereed)
    Abstract [en]

    One way of improving the load capacity of bolted joints in composite components is to use metal inserts locally at the holes in order to reduce the bearing stress. In this paper an innovative local reinforcement concept is introduced where metal inserts are implemented in the form of stacked patches at the holes in order to improve the bearing strength of the composite. After doing some initial tests and a parameter study, some specimens with optimized stacked patch inserts were designed and tested. The specimens with optimized inserts show 50-60% improved bearing strength in pin-loaded tests which corresponds to a potential weight reduction of about 30%. These very promising results indicates that the efficiency of joints in composites can be improved significantly.

  • 2982. Akbarzadeh, Sara
    et al.
    Combes, Richard
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Altman, Zwi
    Self-organizing femtocell offloading at the flow level2013In: International Journal of Network Management, ISSN 1055-7148, E-ISSN 1099-1190, Vol. 23, no 4, p. 259-271Article in journal (Refereed)
    Abstract [en]

    Femtocell technology is expected to be fully self-managed, empowered by self-organizing network functionalities. This paper proposes a solution for self-optimized offloading of macrocell traffic towards open/hybrid-access femtocells. A heterogeneous network comprising macro- and femtocells is modeled as parallel queues. The coverage area of the femtocells is self-optimized by dynamically adapting their pilot powers. A simple update equation for the pilot power is given and its convergence is studied using stochastic approximation techniques. The algorithm balances the load among the cells to improve network capacity. Simulation results illustrate the important performance gains brought about by the proposed scheme, using a dynamic network simulator.

  • 2983. Akcay, H.
    et al.
    Hjalmarsson, Håkan
    Department of Electrical Engineering, Linköping University.
    Ljung, Lennart
    Department of Electrical Engineering, Linköping University.
    On the choice of norms in system identification1996In: IEEE Transactions on Automatic Control, ISSN 00189286 (ISSN), Vol. 41, no 9, p. 1367-1372Article in journal (Refereed)
    Abstract [en]

    In this paper we discuss smooth and sensitive norms for prediction error system identification when the disturbances are magnitude bounded. Formal conditions for sensitive norms, which give an order of magnitude faster convergence of the parameter estimate variance, are developed. However, it also is shown that the parameter estimate variance convergence rate of sensitive norms is arbitrarily bad for certain distributions. A necessary condition for a norm to be statistically robust with respect to the family F(C) of distributions with support [-C, C] for some arbitrary C > 0 is that its second derivative does not vanish on the support. A direct consequence of this observation is that the quadratic norm is statistically robust among all ℓp-norms, p ≀ 2 < ∞ for F(C). ©1996 IEEE.

  • 2984.
    Akdis, M
    et al.
    SIAF, Switzerland.
    Verhagen, J
    SIAF, Switzerland.
    Taylor, A
    SIAF, Switzerland.
    Karamloo, F
    SIAF, Switzerland.
    Karagiannidis, C
    SIAF, Switzerland.
    Crameri, R
    SIAF, Switzerland.
    Thunberg, Sarah
    Karolinska Institutet.
    Deniz, G
    SIAF, Switzerland.
    Valenta, R
    SIAF, Switzerland.
    Fiebig, H
    SIAF, Switzerland.
    Kegel, C
    SIAF, Switzerland.
    Disch, R
    SIAF, Switzerland.
    Schmidt-Weber, C B
    SIAF, Switzerland.
    Blaser, K
    SIAF, Switzerland.
    Akdis, C A
    SIAF, Switzerland.
    Immune responses in healthy and allergic individuals are characterized by a fine balance between allergen-specific T regulatory 1 and T helper 2 cells2004In: Journal of Experimental Medicine, ISSN 0022-1007, E-ISSN 1540-9538, Vol. 199, no 11, p. 1567-1575Article in journal (Refereed)
    Abstract [en]

    The mechanisms by which immune responses to nonpathogenic environmental antigens lead to either allergy or nonharmful immunity are unknown. Single allergen-specific T cells constitute a very small fraction of the whole CD4(+) T cell repertoire and can be isolated from the peripheral blood of humans according to their cytokine profile. Freshly purified interferon-gamma-, interleukin (IL)-4-, and IL-10-producing allergen-specific CD4(+) T cells display characteristics of T helper cell (Th)1-, Th2, and T regulatory (Tr)1-like cells, respectively. Tr1 cells consistently represent the dominant subset specific for common environmental allergens in healthy individuals; in contrast, there is a high frequency of allergen-specific IL-4-secreting T cells in allergic individuals. Tr1 cells use multiple suppressive mechanisms, IL-10 and TGF-beta as secreted cytokines, and cytotoxic T lymphocyte antigen 4 and programmed death 1 as surface molecules. Healthy and allergic individuals exhibit all three allergen-specific subsets in different proportions, indicating that a change in the dominant subset may lead to allergy development or recovery. Accordingly, blocking the suppressor activity of Tr1 cells or increasing Th2 cell frequency enhances allergen-specific Th2 cell activation ex vivo. These results indicate that the balance between allergen-specific Tr1 cells and Th2 cells may be decisive in the development of allergy.

  • 2985.
    Akdogan, Mariam
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Baghdo, Gabriella
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Utvärdering och effektivisering av byggprocessen på Projektgaranti AB2012Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The ame of this examination thesis is to evaluate the operation system at the company Projektgaranti AB and find different approaches and solutions on how to streamline the construction process. The purpose of evaluating the operational system is to get an understanding of Projektgaranti ABs way to work and investigate the use of the system.To carry out this study, we determined three different methods of evaluation that must be done in order to get a broad perspective at the opportunities that the system has to develop. This took the form of sample survey based on five selected projects from the company server. After that a questionnaire was sent out to all employees of the company in Stockholm and Gothenburg. Based on the answers we received we selected two employees from each office to be interviewed.The evaluation result shows the employees' opinions about the system, various improvement and development.To make the construction process more efficient is based on various research techniques. The one which we found to be most profitable for the company's development was the Lean Production, which includes showing different types of waste that can be avoided, how to create value and better planning. If you do it visually and include teamwork and commitment it will lead to a more efficient construction.

  • 2986. Akerman, J. J.
    et al.
    Venturini, E. L.
    Siegal, M. P.
    Yun, S. H.
    Karlsson, U. O.
    Rao, K. V.
    KTH, Superseded Departments, Materials Science and Engineering.
    Two-stage crossover from thermal to quantum flux creep of dilute vortex ensembles in various high-T-c superconducting thin films2001In: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 64, no 9Article in journal (Refereed)
    Abstract [en]

    The thermal-to-quantum flux creep crossover at low vortex densities has been studied in YBa2Cu3O7, TlBa2CaCu2O7-delta, and HgBa2CaCu2O6+delta thin films using ac susceptibility. The crossover temperatures T-cr are 10-11, 17, and 30 K, respectively. Both thermal and quantum flux creep is suppressed as the vortex density is decreased. We observe a two-stage nature in the crossover behavior which appears to be a general property of all the three materials studied.

  • 2987. Akerman, J. J.
    et al.
    Yun, S. H.
    Karlsson, U. O.
    Rao, K. V.
    KTH, Superseded Departments, Materials Science and Engineering.
    Dislocation-mediated creep of highly separated vortices in a-axis-oriented HgBa2CaCu2O6+delta thin films2001In: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 64, no 2Article in journal (Refereed)
    Abstract [en]

    Using ac susceptibility, we determine the critical current density J(c) and the flux creep activation energy U of an a-axis-oriented HgBa2CaCu2O6+delta thin film. The critical current density at helium temperatures is found to be 4.6 x 10(4) A/cm(2), i.e., about two orders of magnitude smaller than for corresponding films with c-axis orientation. The temperature and ac field dependent activation energy is consistent with dislocation-mediated flux creep and well described by U(T,H-ac)=U-o(1-t(4))H-ac(-1/2) with t=T/T-c, T-c=120K, and U-o = 0.77 eV Oe(1/2) for temperatures T>45 K and in the field range studied. The activation energy is of the same order as that found in c-axis-oriented films. Below T = 45 K the activation energy is observed to decrease as thermally assisted quantum creep becomes increasingly important.

  • 2988. Akesson, M.
    et al.
    Gustafsson, E.
    Johansson, Karl Henrik
    Control design for a helicopter lab process1996Conference paper (Refereed)
  • 2989.
    Akeyo Forsman, Prisca
    KTH, School of Industrial Engineering and Management (ITM), Applied Mechanical Engineering (KTH Södertälje).
    A Study of Construction Project Stakeholders’ Management Methods and the Critical Success Factors Essential for Successful Management in Stockholm Region.2017Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
  • 2990.
    Akfidan, Johny
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Sadek, Rafed
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Dimensionering och utförande av bottenplattor utsatta för upptryck2012Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    När en konstruktion byggs på det viset att dess bottenplatta hamnar under grundvattenytan, skapas ett grundvattentryck upp mot bottenplattan och konstruktionen, som kan åstadkomma stora problem. Grundvattnet, som tryckts undan av konstruktionen, vill nå upp till sin ursprungliga nivå och därmed trycka med sig konstruktionen upp. Detta fenomen kallas hydraulisk bottenupptryckning. Fenomenet kan motverkas på olika sätt, där rapporten beaktar två olika sätt att motverka hydraulisk bottenupptryckning på: genom en bottenplatta som är tyngre än grundvattentrycket eller förankra bottenplattan mot ett fast underlag.

    Genom att uppmärksamma och sammanställa projekt (huvudsakligen konstruerade av Tyréns) som tagit hänsyn till ovan nämnda fenomen vid dimensioneringen av bottenplattan, har en rapport skapats. Denna rapport ska finnas för att åstadkomma kunskapsåterföring av de problem som uppstått i projekten och deras lösningar.

    Utöver att skapa en rapport där de berörda projekten sammanställs ska en bottenplatta optimeras, huvudsakligen med hänseende till bottenplattans tjocklek och dess bärförmåga mot genomstansning för olika förankringstyper. Optimeringen ska ske i enlighet med, huvudsakligen Eurokod 2 kapitlen 6.4 och 7.3. Det har bestämts att tre tjocklekar på bottenplattan ska beaktas, och dessa är 400, 550 och 800 mm. Genom diskussioner med våra handledare, sakkunnig personal på Tyréns och representanter inom branschen, valdes ett antal förankringstyper som skulle jämföras. För att kunna jämföra kombinationerna av de olika tjocklekarna på bottenplattan och de olika förankringstyperna, har Tyréns projekt Biomedicum med dess förutsättningar, utnyttjats som referensobjekt.

    Att ta fram de inre krafterna i bottenplattan via handberäkningar är mycket komplicerat och tidskrävande för att rymmas inom ramen för denna studie. Därför används programmet FEM Plate (Strusoft) för att ta fram dessa krafter. De inre krafter som tas fram från FEM Plate utnyttjas sedan för att med hjälp av handberäkningar, i enlighet Eurokod 2, dimensionera Biomedicums bottenplatta enligt de moment som krävs.

    Jämförelsen av de olika kombinationerna visar på att bottenplattan 400 mm med förankringstypen stålkärna av diameter 80 mm från Inexa Profil är den optimala lösningen för Biomedicums bottenplatta. Denna förankringstyp (för bottenplattan 400 mm) är den enda som får en tillräcklig bärförmåga mot genomstansning av bottenplattan, endast med åtgärden skjuvarmering runtomkring förankringen.

    En föreslagen lösning på hur förankringstypen bör monteras i bottenplattan har tagits fram. Diskussioner med sakkunnig personal från Minova (tillverkare av MAI-förankringen) har lett till övertygelsen om att föreslagen lösning fungerar utan några kapacitetsförsämringar på förankringen. En modellering av bottenplattan 400 mm med föreslagen lösning på MAIförankringen och efterföljande handberäkningar, visar att lösningen optimerar bottenplattan än mer. föreslagen lösning på monteringen i bottenplattan bör dessutom kunna tillämpas på de andra förankringstyperna, men har endast beaktats för MAI-förankringen.

    Eftersom fokus endast är på att den optimala bottenplattan är 400 mm och ingen hänsyn tas till kostnaderna, är föreslagen lösning på MAI-staget den optimala lösningen. Det är den enda förankringen som har en tillräcklig bärförmåga mot genomstansning för bottenplattan 400 mm, utan några som helst extra åtgärder.

    En bottenplatta med vot under förankringen bör undvikas, eftersom förtjockningen av bottenplattan under förankringen kräver mycket extra tid i utförande. Därför rekommenderas det att en jämntjock bottenplatta dimensioneras med eventuell skjuvarmering, om bottenplattans bärförmåga mot genomstansning inte är tillräcklig utan skjuvarmering.

    Den optimering som tagits fram är en generalisering av Biomedicums bottenplatta. Detta leder till att de modeller och beräkningar som gjorts, enkelt kan implementeras på andra bottenplattor med samma problem genom att justera indata.

  • 2991.
    Akhand, Victoria
    KTH, School of Chemical Science and Engineering (CHE).
    Mass Balance Model of Impurities for the WoodRoll Process2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The depletion time for fossil fuels calculated from 2009 is 35 years for oil, 37 years for gas

    and 107 years for coal. Hence, it has become essential to reduce the dependence on fossil

    fuels by switching over to renewable resources. This in turn will also help in combating the

    negative effects on the environment like global warming. Thermochemical processes such as

    pyrolysis and gasification of biomass are considered the most efficient technology for

    converting biomass to useful energy carriers. Cortus Energy AB is a Swedish company that

    has developed a patented gasification technology called WoodRoll

    ® for gasification of fuels derived from biomass. However, ash in a thermochemical conversion process can cause

    corrosion, sintering, slag and poisoning of catalysts, which leads to operational problems. In

    addition, heavy metals such as Zn, Pb and Cd are environmentally problematic. These metals

    contribute to environmental pollution by contaminating the soil, which in turn can harm

    humans and the ecosystem via the food chain. The undesired elements should therefore be

    identified to minimize their impact on the overall thermochemical process and to reduce the

    emission of these harmful substances.

    The objective of this master thesis project, on behalf of Cortus Energy AB, was to investigate

    possible key numbers that can be used to describe and predict how the ash behaves in their

    patented WoodRoll® process. The key numbers that have been identified are empirically

    developed based on experience of coal combustion. These key numbers are regularly used for

    fuel derived from biomass by companies specializing in analyzing, although knowledge about

    whether they can actually be used on biomass is limited. In order to ensure that the use of

    these for biomass is correct, they must be experimentally verified in the future. In addition, a

    theoretical investigation is conducted to study which species can form and in what phase this

    occurs. The investigation reveals that there are no clear trends for how the inorganic elements

    behave since contradicting results from different studies have been reported. Formation of

    species and their phase depends on several parameters such as temperature, heating rate,

    particle size, volatility, quantity and interaction between the elements in the biomass. The

    thesis project ends with a mass balance model on selected inorganic elements for wood

    residues, as well as for bark. The model could be a tool for Cortus Energy AB to identify

    approximately how much of each element is present in each stream in the WoodRoll® process.

    The models are verified with analysis results. Inorganic elements that affect the

    overall process and its equipment have been selected for modelling. The volume percent of

    H2, CO, CO2 and CH4 in the models agree well with the values obtained by Cortus Energy

    AB. This shows that the thermodynamic equilibrium calculations performed are reasonable.

  • 2992.
    Akhand, Victoria
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Celsi, Adrian
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Lagerberg, Tove
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Sångberg, Oscar
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Plastfilm från rapshalm2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The purpose of this project is to extract hemicellulose from the rape straw by using alkali- and water extraction, and thereafter to produce a film with these polymers. The intention with this film is to eventually replace the present oxygen barrier made of aluminium in applications such as food packaging made of cardboard, among other things. The film is composed of hemicellulose and additives, either the CMC or sorbitol molecules. Many analyses were conducted on the extracts and the films in order to draw conclusions about the structure and properties. The NMR analysis showed that the extracts contained the expected sugars and that the main deacetylation of O-acetyl groups happened during the extraction with low alkali. The SEC analysis gave low values of Đ. The tensile testing gave exceptional results, namely elongations of 10-60%, depending on the composition of the films. Two of the most significant analyses are the ion chromatography and the oxygen permeability test, which could not be implemented because of technical difficulties. Low alkali is to be preferred as solvent, used to extract the polymers, with respect to the environment, the economy and the mechanical properties. Furthermore, high addition of CMC is preferred when producing films because low CMC and sorbitol resulted in sticky films. For future work it would be recommended to analyse the films by conducting the ion chromatography and the oxygen permeability test. Additionally, it would be desirable to find the optimal addition amount of the CMC.

  • 2993.
    Akhlaghi, Shahin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Degradation of acrylonitrile butadiene rubber and fluoroelastomers in rapeseed biodiesel and hydrogenated vegetable oil2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Biodiesel and hydrotreated vegetable oil (HVO) are currently viewed by the transportation sector as the most viable alternative fuels to replace petroleum-based fuels. The use of biodiesel has, however, been limited by the deteriorative effect of biodiesel on rubber parts in automobile fuel systems. This work therefore aimed at investigating the degradation of acrylonitrile butadiene rubber (NBR) and fluoroelastomers (FKM) on exposure to biodiesel and HVO at different temperatures and oxygen concentrations in an automated ageing equipment and a high-pressure autoclave. The oxidation of biodiesel at 80 °C was promoted by an increase in the oxygen partial pressure, resulting in the formation of larger amounts of hydroperoxides and acids in the fuel. The fatty acid methyl esters of the biodiesel oxidized less at 150 °C on autoclave aging, because the termination reactions between alkyl and alkylperoxyl radicals dominated over the initiation reactions. HVO consists of saturated hydrocarbons, and remained intact during the exposure. The NBR absorbed a large amount of biodiesel due to fuel-driven internal cavitation in the rubber, and the uptake increased with increasing oxygen partial pressure due to the increase in concentration of oxidation products of the biodiesel. The absence of a tan δ peak (dynamical mechanical measurements) of the bound rubber and the appearance of carbon black particles devoid of rubber suggested that the cavitation was caused by the detachment of bound rubber from particle surfaces. A significant decrease in the strain-at-break and in the Payne-effect amplitude of NBR exposed to biodiesel was explained as being due to the damage caused by biodiesel to the rubber-carbon-black network. During the high-temperature autoclave ageing, the NBR swelled less in biodiesel, and showed a small decrease in the strain-at-break due to the cleavage of rubber chains. The degradation of NBR in the absence of carbon black was due only to biodiesel-promoted oxidative crosslinking. The zinc cations released by the dissolution of zinc oxide particles in biodiesel promoted reduction reactions in the acrylonitrile part of the NBR. Heat-treated star-shaped ZnO particles dissolved more slowly in biodiesel than the commercial ZnO nanoparticles due to the elimination of inter-particle porosity by heat treatment. The fuel sorption was hindered in HVO-exposed NBR by the steric constraints of the bulky HVO molecules. The extensibility of NBR decreased only slightly after exposure to HVO, due to the migration of plasticizer from the rubber. The bisphenol-cured FKM co- and terpolymer swelled more than the peroxide-cured GFLT-type FKM in biodiesel due to the chain cleavage caused by the attack of biodiesel on the double bonds formed during the bisphenol curing. The FKM rubbers absorbed biodiesel faster, and to a greater extent, with increasing oxygen concentration. It is suggested that the extensive biodiesel uptake and the decrease in the strain-at-break and Young’s modulus of the FKM terpolymer was due to dehydrofluorination of the rubber by the coordination complexes of biodiesel and magnesium oxide and calcium hydroxide particles. An increase in the CH2-concentration of the extracted FKM rubbers suggested that biodiesel was grafted onto the FKM at the unsaturated sites resulting from dehydrofluorination.

  • 2994.
    Akhlaghi, Shahin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Amir Masoud, Pourrahimi
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Christian, Sjöstedt
    Martin, Bellander
    Mikael S., Hedenqvist
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Ulf W., Gedde
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Degradation of fluoroelastomers in rapeseed biodiesel at different oxygen concentrations2017In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 136, p. 10-19Article in journal (Refereed)
    Abstract [en]

    The degradation of fluoroelastomers (FKM) based on different monomers, additives and curing systems was studied after exposure to rapeseed biodiesel at 100 °C and different oxygen partial pressures. The sorption of fuel in the carbon black-filled FKM terpolymer was promoted by the fuel-driven cavitation in the rubber. The bisphenol-cured rubbers swelled more in biodiesel than the peroxide-cured FKM, presumably due to the chain cleavage caused by the attack of biodiesel on the double bonds formed during the bisphenol curing. With any of the selected types of monomer, the FKM rubbers absorbed biodiesel faster and to a greater extent with increasing oxygen partial pressure due to the increase in concentration of the oxidation products of biodiesel. Water-assisted complexation of biodiesel on magnesium oxide and calcium hydroxide particles led to dehydrofluorination of FKM, resulting in an extensive fuel uptake and a decrease in the strain-at-break and the Young's modulus of the rubbers. An increase in the CH2-concentration determined by infrared spectroscopy, and the appearance of biodiesel flakes in scanning electron micrographs of the extracted rubbers, were explained as being due to the presence of insoluble biodiesel grafted onto FKM on the unsaturated sites resulting from dehydrofluorination. The extensibility of the GFLT-type FKM was the least affected on exposure to biodiesel because this rubber contained less unsaturation and metal oxide/hydroxide particles.

  • 2995.
    Akhlaghi, Shahin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials. Scania CV AB, Sweden.
    Gedde, Ulf W.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Hedenqvist, Mikael S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Brana, Maria T. Conde
    Bellander, Martin
    Deterioration of automotive rubbers in liquid biofuels: A review2015In: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 43, p. 1238-1248Article, review/survey (Refereed)
    Abstract [en]

    Concerns over the fast depletion of fossil fuels, environmental issues and stringent legislation associated with petroleum-based fuels have triggered a shift to bio-based fuels, as an alternative to meet the growing energy demand in the transportation sector. However, since conventional automobile fuel systems are adapted to petroleum-based fuels, switching to biofuels causes a severe deterioration in the performance of currently used rubber components. The degradation of the rubber materials in biofuels is complicated by the presence of different additives in biofuels and rubber compounds, by oxidation of biofuels and by the effects of thermomechanical loadings in the engine. This paper presents a comprehensive review of the effects of different types of biofuels, particularly biodiesel and bioethanol, on the physical, mechanical, morphological and thermal properties of elastomers under different exposure conditions. In addition, the literature data available on the variation of rubbers' resistance to biofuels with the changes in their monomer type and composition, cure system and additives content was also studied. The review essentially focuses on the compatibility of biofuels with acrylonitrile butadiene rubber, fluoroelastomers, polychloroprene rubber and silicon rubber, as the most commonly used automotive rubbers coming into contact with fuels during their service. The knowledge summarized in this study can help to develop a guideline on the selection of rubber for automotive parts designed to withstand biofuels.

  • 2996.
    Akhlaghi, Shahin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Hedenqvist, Mikael S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Brana, M. T. Conde
    Bellander, M.
    Gedde, Ulf W.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Deterioration of acrylonitrile butadiene rubber in rapeseed biodiesel2015In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 111, p. 211-222Article in journal (Refereed)
    Abstract [en]

    The deterioration of acrylonitrile butadiene rubber (NBR) exposed to rapeseed biodiesel at 90 degrees C was studied. The oxidation of biodiesel and NBR during ageing was monitored by H-1 NMR and infrared spectroscopy, HPLC and titration methods. The oxidation of biodiesel was impeded in the presence of NBR, but promoted in biodiesel-exposed rubber. This was explained as being due to the migration of stabilizer from the rubber to biodiesel, the diffusion of dissolved oxygen from biodiesel into NBR and the absorption of oxidation precursors of biodiesel by the rubber. The resemblance between the anomalous sorption kinetics of biodiesel in NBR and the equilibrium benzene uptake by the aged rubbers revealed that biodiesel caused a network defect in NBR, resulting in a gradual increase in the equilibrium swelling. The cleavage of crosslinks was implausible since the Young's modulus of the rubber at low strains, disregarding an initial decrease, increased with increasing exposure time. The appearance of 'naked' carbon black particles in the scanning electron micrographs of the aged rubbers and a drastic decrease in the strain-at-break of NBR after exposure to biodiesel suggests that internal cavitation was caused by the attack of biodiesel on the acrylonitrile units of NBR.

  • 2997.
    Akhlaghi, Shahin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Pourrahimi, A. M.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Christian, Sjöstedt
    Martin, Bellander
    Mikael S., Hedenqvist
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Ulf W., Gedde
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Effects of ageing conditions on degradation of acrylonitrile butadiene rubber filled with heat-treated ZnO star-shaped particles in rapeseed biodiesel2017In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321Article in journal (Refereed)
    Abstract [en]

    The degradation of acrylonitrile butadiene rubber (NBR) after exposure to biodiesel at different oxygen partial pressures in an automated ageing equipment at 80 °C, and in a high-pressure autoclave at 150 °C was studied. The oxidation of biodiesel was promoted by an increase in oxygen concentration, resulting in a larger uptake of fuel in the rubber due to internal cavitation, a greater decrease in the strain-at-break of NBR due to the coalescence of cavity, and a faster increase in the crosslinking density and carbonyl index due to the promotion of the oxidation of NBR. During the high-temperature autoclave ageing, less fuel was absorbed in the rubber, because the formation of hydroperoxides and acids was impeded. The extensibility of NBR aged in the autoclave decreased only slightly due to the cleavage of rubber chains by the biodiesel attack. The degradation of NBR in the absence of carbon black was explained as being due to oxidative crosslinking. The dissolution of ZnO crystals in the acidic components of biodiesel was retarded by removing the inter-particle porosity and surface defects through heat treating star-shaped ZnO particles. The rubber containing heat-treated ZnO particles swelled less in biodiesel than a NBR filled with commercial ZnO nanoparticles, and showed a smaller decrease in the strain-at-break and less oxidative crosslinking.

  • 2998.
    Akhlaghi, Shahin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Pourrahimi, Amir Masoud
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Hedenqvist, Mikael
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Sjöstedt, C.
    Bellander, M.
    Gedde, Ulf
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Degradation of carbon-black-filled acrylonitrile butadiene rubber in alternative fuels: Transesterified and hydrotreated vegetable oils2016In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 123, p. 69-79Article in journal (Refereed)
    Abstract [en]

    The deterioration of acrylonitrile butadiene rubber (NBR), a common sealing material in automobile fuel systems, when exposed to rapeseed biodiesel and hydrotreated vegetable oil (HVO) was studied. The fuel sorption was hindered in HVO-exposed rubber by the steric constraints of bulky HVO molecules, but it was promoted in biodiesel-exposed rubber by fuel-driven cavitation in the NBR and by the increase in diffusivity of biodiesel after oxidation. The absence of a tan δ peak of the bound rubber and the appearance of carbon black particles devoid of rubber suggested that the cavitation was made possible in biodiesel-aged rubber by the detachment of bound rubber from particle surfaces. The HVO-exposed NBR showed a small decrease in strain-at-break due to the migration of plasticizer from the rubber, and a small increase in the Young’s modulus due to oxidative crosslinking. A drastic decrease in extensibility and Payne-effect amplitude of NBR on exposure to biodiesel was explained as being due to the damage caused by biodiesel to the continuous network of bound rubber-carbon black. A decrease in the ZnO crystal size with increasing exposure time suggested that the particles are gradually dissolved in the acidic components of oxidized biodiesel. The Zn2+ cations released from the dissolution of ZnO particles in biodiesel promoted the hydrolysis of the nitrile groups of NBR.

  • 2999. Akhmadaliev, S.
    et al.
    Albiol, F.
    Amaral, P.
    Berglund, S.
    Lund-Jensen, Bengt
    KTH, Superseded Departments, Physics.
    Lundquist, J.
    Sellden, B.
    Soderqvist, J.
    Zolnierowski, Y. P.
    et al,
    Results from a new combined test of an electromagnetic liquid argon calorimeter with a hadronic scintillating-tile calorimeter2000In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 449, no 3, p. 461-477Article in journal (Refereed)
    Abstract [en]

    A new combined test of an electromagnetic liquid argon accordion calorimeter and a hadronic scintillating-tile calorimeter was carried out at the CERN SPS. These devices are prototypes of the barrel calorimeter of the future ATLAS experiment at the LHC. The energy resolution of pions in the energy range from 10 to 300 GeV at an incident angle a of about 12 degrees is well described by the expression sigma/E = ((41.9 +/- 1.6)%/root E + (1.8 +/- 0.1)%)circle plus(1.8 +/- 0.1)/E, where E is in GeV. The response to electrons and muons was evaluated. Shower profiles, shower leakage and the angular resolution of hadronic showers were also studied. Results are compared with those from the previous beam test.

  • 3000. Akhmadaliev, S.
    et al.
    Amaral, P.
    Ambrosini, G.
    Amorim, A.
    Anderson, K.
    Johansson, E.
    Lund-Jensen, Bengt
    KTH, Superseded Departments, Physics.
    Soderqvist, J.
    Zolnierowski, Y. P.
    et al,
    Hadron energy reconstruction for the ATLAS calorimetry in the framework of the non-parametrical method2002In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 480, no 03-feb, p. 508-523Article in journal (Refereed)
    Abstract [en]

    This paper discusses hadron energy reconstruction for the ATLAS barrel prototype combined calorimeter (consisting of a lead-liquid argon electromagnetic part and an iron-scintillator hadronic part) in the framework of the non-parametrical method. The non-parametrical method utilizes only the known e/h ratios and the electron calibration constants and does not require the determination of any parameters by a minimization technique. Thus, this technique lends itself to an easy use in a first level trigger. The reconstructed mean values of the hadron energies are within +/-1% of the true values and the fractional energy resolution is [(58+/-3)%/rootE+(2.5+/-0.3)%]circle plus(1.7+/-0.2)/E. The value of the e/h ratio obtained for the electromagnetic compartment of the combined calorimeter is 1.74+/-0.04 and agrees with the prediction that e/h > 1.66 for this electromagnetic calorimeter. Results of a study of the longitudinal hadronic shower development are also presented. The data have been taken in the H8 beam line of the CERN SPS using pions of energies from 10 to 300 GeV.

57585960616263 2951 - 3000 of 121971
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