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  • 124151.
    Zander, Jens
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Mähönen, Petri
    Riding the Data Tsunami in the Cloud: Myths and Challenges in Future Wireless Access2013In: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 51, no 3, p. 145-151Article in journal (Refereed)
    Abstract [en]

    Data rates of mobile communications have increased dramatically during the last decade. The industry predicts an exponential increase of data traffic that would correspond to a 1000-fold increase in traffic between 2010 and 2020. These figures are very similar to ones reported during the last Internet boom. In this article we assess the realism of these assumptions. We conjecture that wireless and mobile Internet access will emerge as a dominant technology. A necessary prerequisite for this development is that wireless access is abundant and becomes (almost) free. A consequence is that the projected capacity increase must be provided at the same cost and energy consumption as today. We explore technical and architectural solutions that have realistic possibility to achieve these targets. We ask if Moore's law, which has successfully predicted the tremendous advances in computing and signal processing, will also save the day for high-speed wireless access. We argue that further improvements of the PHY layer are possible, but it is unlikely that this alone provides a viable path. The exponential traffic increase has to be matched mainly by increasing the density of the access networks as well as providing a modest amount of extra spectrum. Thus, the future research challenges are in designing energy-and cost-efficient short-range architectures and systems that support super-dense deployments. A non-technical complication is that such infrastructures are likely to lead to highly fragmented markets with a large number of operators and infrastructure owners.

  • 124152.
    Zander, Jens
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Rasmussen, Lars K.
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Sung, Ki Won
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Maehoenen, Petri
    Petrova, Marina
    Jantti, Riku
    Kronander, Jonas
    On the scalability of cognitive radio:: Assessing the commercial viability of secondary spectrum access2013In: IEEE wireless communications, ISSN 1536-1284, E-ISSN 1558-0687, Vol. 20, no 2, p. 28-35Article in journal (Refereed)
    Abstract [en]

    We report results from the recently finished QUASAR project, which has studied overall system aspects of cognitive radio technologies and has paid attention particularly to the economic viability of different use cases. We find that successful secondary sharing goes far beyond the detection of spectrum holes. Large-scale commercial success requires that secondary systems are scalable so that a large number of users can be served in an economically viable fashion. Our key finding is that secondary spectrum use is not an attractive method for most of the commercially interesting scenarios, from neither a business nor technical perspective. Perhaps somewhat surprisingly, the likely commercial "sweet spot" for secondary sharing in the lower frequency bands is short-range indoor communications. We also find that regulation does not currently present a significant barrier in Europe or the United States.

  • 124153.
    Zander, Jens
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Sung, Ki Won
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Opportunistic Secondary Spectrum Access: Opportunities and Limitations2012In: Radio Science Bulletin, ISSN 1024-4530, no 340, p. 29-33Article in journal (Refereed)
    Abstract [en]

    The dynamic spectrum-sharing technique (“cognitiveradio”), where secondary users opportunistically utilize temporarily or locally unused spectrum, has emerged as a prime candidate technology for relieving the perceived spectrum shortage in the lower frequency bands. Makinga realistic assessment of the amount of spectrum availablefor secondary services was the objective of the EU FP7QUASAR project. In the project, it was found to be fundamentally difficult to reliably determine which part of the spectrum is available. This leads to large safety marginsand to poor spectrum utilization, in general. Furthermore, the business success of future systems depends on thescalability of the secondary-access techniques. Resultsfrom the project indicate that in large-scale deployment,the aggregate interference from the secondary devices isthe key bottleneck. This aggregate interference is difficult for the individual secondary-spectrum user to assess. Inaddition, the vast majority of spectrum opportunities arestrongly dependent on the intended use. They are highly localized in time and space, and not obviously suitable for reliable service provisioning. The exception has been shown to be short-range, indoor communications, where the low transmitter power, walls, and other obstructions successfully provide these margins.

  • 124154.
    Zander, Jens
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Sung, Ki Won
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Opportunistic secondary spectrum access-opportunities and limitations2011In: 2011 30th URSI General Assembly and Scientific Symposium, URSIGASS 2011, 2011Conference paper (Refereed)
    Abstract [en]

    Dynamic spectrum sharing technique ( #x201C;Cognitive Radio #x201D;) where secondary users opportunistically utilize temporarily or locally unused spectrum has emerged as a prime candidate technology to relieve the perceived spectrum shortage. Making a realistic assessment of the amount of spectrum available for secondary services is the objective of the EU FP7 QUASAR project. In the project it is found to be fundamentally difficult to reliably determine which part of the spectrum is available, which leads to large safety margins consequently to poor spectrum utilization. Further, the business success of future systems depends on the scalability of the secondary access techniques. Also, the vast majorities of spectrum opportunities are highly localized in time and spaces and strongly dependent on the intended use such that they defy common models for spectrum trading.

  • 124155.
    Zander, Jens
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Sung, Ki Won
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Nekovee, Maziar
    BT Research.
    Kronander, Jonas
    Ericsson AB.
    Kim, S-L
    Yonsei University.
    Achtzehn, Andreas
    RWTH Aachen University.
    QUASAR scenarios for white space assessments and exploitation2010In: URSI EMC conference, 2010Conference paper (Refereed)
    Abstract [en]

    This paper presents a unifying scenario classification model and a selection of scenarios, developed within the EU FP7 QUASAR project to study secondary spectrum usage. The classification model categorizes scenarios from technical, regulatory, and economic perspective. It enables the derivation of the most promising scenarios of secondary spectrum access: Cellular and WiFi-like usage of TV white spaces, wireless backhauling using secondary spectrum access, license exempt use of the radar bands, use of the aeronautical bands for mobile broadband and cognitive machine-to-machine communication. These scenarios are presented in more detail along with motivations of why they are interesting to study further. The scenarios will provide the basis for the future work within the QUASAR project, which has the overall objective to assess the amount of useful spectrum opportunities for secondary spectrum access.

  • 124156.
    Zander, Jens
    et al.
    KTH, Superseded Departments, Teleinformatics.
    Åhl, Karl-Axel
    Time Space Radio AB.
    Capacity Of Time-Space Switched Cellular Radio Link Systems For Metropolitan-Area Networks1992In: IEE Proceedings - Part I: Communications, Speech & Vision, ISSN 0956-3776, Vol. 139, no 5, p. 533-538Article in journal (Refereed)
    Abstract [en]

    Using multipoint-radio link systems constitutes a viable alternative to copper and optical fibres for high-capacity local distribution of telephone and data traffic. A novel to architecture for a fixed cellular radio system is proposed. The proposed system uses electronically steerable antennas to combine time and `space' multiplexing. Assuming an urban environment and a high user density, the performance of the TDMA system is estimated for some simple propagation and interference models. Results indicate that, owing to the time-space multiplexing technique, the performance exceeds the performance of conventional multipoint systems by an order of magnitude. Owing to the unique features of the system, several central stations may be operated at the same site at the same frequency, to boost the capacity even more.

  • 124157.
    Zander, Jens
    et al.
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Åhl, Karl-Axel
    Time Space Radio AB.
    On the Capacity of Time-Space Switched Cellular Radio Link Systems for Metropolitan Area Networks1991Report (Other academic)
  • 124158.
    Zander, Jens
    et al.
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Åhl, Karl-Axel
    Time Space Radio AB.
    On the Performance of Time-Space Switched Multipoint Radio Link Systems1992Conference paper (Refereed)
  • 124159.
    Zander, Johan
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Technology.
    Development of tools for integrated optimisation and use of aluminium alloys2011Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Commercial alloys are continuously developed to improve their performance. Therefore it is useful to establish new optimisation software, which could be used in development of new materials or in materials selection. In the first part of the thesis, mechanical and technological properties, which are of importance in materials selection in mechanical design, are investigated. Two types of materials are analysed for the mechanical properties, aluminium alloys and stainless steels but only aluminium alloys for the technological properties.

    Thermodynamic analysis has been used to evaluate the effect of the microstructure. Solid solution hardening has been successfully modelled for both aluminium alloys and stainless steels following the theories by Labusch and Nabarro. The precipitation hardening is most dominant for the hardenable aluminium alloys, but the non-hardenable alloys also increase their strength from precipitation hardening. The non-hardenable alloys are divided into different tempers, which differ in the amount of strain hardening. This has also been modelled successfully.

    Combining these fundamental results with multiple regressions, models for mechanical and technological properties have been created. Separate models are developed for wrought aluminium alloys and stainless steels. For the aluminium alloys these include the solid solution hardening and the precipitation hardening. For the stainless steels, the thickness, nitrogen content and ferrite content are included together with the solid solution hardening.

    The second part of the thesis concerns materials selection and materials optimisation. Traditionally materials optimisation includes a preliminary sifting due to the vast number of engineering materials. Then there is a discriminating search followed by an optimisation. In the optimisation part the concept merit indices could be used to rank the materials. A merit index only includes material properties, as for example the characteristic strength, the density or the Young’s modulus. A concept related to the merit indices are the merit exponents, which can be used when no explicit functions for the merit indices are available. The merit exponents can also be used when creating a control area diagram (CAD). These diagrams are used as a design tool, where both the geometry and materials are taken into account. For a situation with several geometrical variables the merit exponents can give information of how much the target function will be influenced by a given property change. This technique can be used for a variety of situations, when there is more than one property limiting the final sizes of a component. Principles for setting up a CAD are given together with how the merit indices and exponents relate to the final CAD.

  • 124160.
    Zander, Johan
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Modelling mechanical properties by analysing datasets of commercial alloys2007Licentiate thesis, comprehensive summary (Other scientific)
    Abstract [en]

    Commercial alloys are continuously developed to improve their performance. Therefore it is important to develop new optimisation software, which could be used in development of new materials or in materials selection. In this study the mechanical properties which are important in materials selection in mechanical design are investigated. Two types of materials are analysed, aluminium alloys and stainless steels but focus will be on the aluminium alloys.

    Thermodynamic analysis has been used to evaluate the effect of the microstructure. Solid solution hardening has been successfully modelled for both aluminium alloys and stainless steels and follows the theories by Labusch and Nabarro. The precipitation hardening is most dominant for the hardenable aluminium alloys, but the non-hardenable alloys also increase their strength from precipitation hardening. The non-hardenable alloys are divided into tempers, which differ in the amount of strain hardening. This has also been modelled successfully.

    Combining these fundamental results with multiple regression, models for mechanical properties have been created. Separate models are developed for wrought aluminium alloys and stainless steels. For the aluminium alloys this includes the solid solution hardening and the precipitation hardening. For the stainless steels the thickness, nitrogen content and ferrite content are included together with the solid solution hardening.

  • 124161.
    Zander, Johan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Technology.
    Sandström, Rolf
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Technology.
    Materials selection for a cooling plate using control area diagrams2011In: Materials & Design, ISSN 0261-3069, Vol. 32, no 10, p. 4866-4873Article in journal (Refereed)
    Abstract [en]

    Merit indices are used to rank materials and are of fundamental importance in materials selection. Traditionally, merit indices have only been available for elementary design cases. In the present paper merit indices are generalised to cooling systems where heat flow and strength are design criteria in a materials optimisation framework. A cooling tube and a cooling plate are considered. A new concept, merit exponent is used that is related to the merit indices. A definition of the merit exponent is given also for cases with many design variables. In each design case a number of merit exponents are involved. It is a nontrivial task to identify which they are and when each of them is applicable. For this purpose control area diagrams (CAD) are used. A CAD is a diagram with the controlling properties on the axes, and areas where one or more constraints are active. For the cooling systems the controlling properties are heat conductivity and strength. The active constraints define the relevant merit exponent. The constraints involve the controlling properties and geometrical variables. Principles are established for how to set up the CAD and to derive the merit exponents.

  • 124162.
    Zander, Johan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Technology.
    Sandström, Rolf
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Technology.
    Materials selection with several sizing variables taking environmental impact into account2012In: Materials and Design, ISSN 0261-3069, Vol. 37, p. 243-250Article in journal (Refereed)
    Abstract [en]

    In two recent papers by the authors in Materials and Design it was shown how efficient materials optimisation can be performed in realistic design cases with several sizing (geometrical) variables. In the present paper this analysis is expanded to take environmental impact into account. Two approaches are considered for the materials optimisation. In the first one, the environmental impact is considered as a constraint and the solution in found with the help of a control area diagram (CAD). In the second approach trade-off values for the environmental impact are used. The approaches are applied to a pressure vessel where the geometry is defined by four geometrical variables. Four pressure vessel steels and three aluminium alloys are used in the analysis. Merit indices and merit exponents are systematically used to solve the material optimisation problem. As expected the optimum material is strongly dependent on the chosen target functions and constraints. It is demonstrated that the two approaches for materials optimisation give identical results.

  • 124163.
    Zander, Johan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Technology.
    Sandström, Rolf
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Technology.
    Merit exponents and control area diagrams in materials selection2011In: Materials & Design, ISSN 0261-3069, Vol. 32, no 10, p. 4850-4856Article in journal (Refereed)
    Abstract [en]

    Merit indices play a fundamental role in materials selection, since they enable ranking of materials. However, the conventional formulation of merit indices is associated with severe limitations. They are dependent on the explicit solution of the variables in the equations for the constraints from the design criteria. Furthermore, it is not always easy to determine which the controlling merit index is. To enable the ranking of materials in more general design cases, merit exponents are introduced as generalisations of the merit indices. Procedures are presented for how to compute the merit exponents numerically without having to solve equations algebraically. Merit exponents (and indices) are only valid in a certain range of property values. To simplify the identification of the controlling merit exponent, it is suggested that so called control area diagrams are used. These diagrams consist of a number of domains, each showing the active constraints and the controlling merit exponent. It is shown that the merit exponents play a crucial role when the control area diagram (CAD) is set up. The principles in the paper are developed for mechanically loaded components and are illustrated for engineering beams with two or three geometric variables.

  • 124164.
    Zander, Johan
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Sandström, Rolf
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Technology.
    Modelling technological properties of commercial wrought aluminium alloys2009In: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 30, no 9, p. 3752-3759Article in journal (Refereed)
    Abstract [en]

    The purpose of this paper is to model three important technological properties for aluminium alloys, based on their performance indices. The models are based on the chemical compositions and microstructure characteristics which are calculated using thermodynamical calculations. The properties that were modelled are the general corrosion, the weldability (MIG and TIC) and the machinability. The results from these models are to be used in materials selection and optimisation. The models clearly show that the general corrosion resistance is reduced for all alloy additions, except for small amounts of titanium. The largest influence on the corrosion is from copper and zinc. The weldability is negatively influenced by the copper and zinc-content, and for small additions of zirconium and titanium it is increased. The machinability is positively influenced by the hardness of the alloy or by adding lead or bismuth. For the non-heat-treatable alloys there was no influence from the composition to the corrosion resistance or the weldability. Copper and zinc which are added to increase the strength to the alloy strongly reduce both the weldability and the corrosion resistance but due to the increase in hardness increase the workability.

  • 124165.
    Zander, Johan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Sandström, Rolf
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    One parameter model for strength properties of hardenable aluminium alloys2008In: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 29, no 8, p. 1540-1548Article in journal (Refereed)
    Abstract [en]

    Models for strength properties are proposed for commercially aluminium alloys. The alloy group investigated are the hardenable alloys from the 2000 (Al-Cu and Al-Cu-Mg), 6000 (Al-Mg-Si) and 7000 (Al-Zn-Mg) series. The same model for solid solution hardening that has successfully been applied to non-hardenable alloys has been used. For precipitation hardening, particle cutting and the Orowan mechanism have been considered. The same basic model is used for all strength properties. It is demonstrated that with one fitting parameter for each property, a representation with reasonable accuracy can be obtained that is applicable to a wide range of alloys. Such models are useful in materials optimisation and selection.

  • 124166.
    Zander, Johan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Sandström, Rolf
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Vitos, Levente
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Modelling mechanical properties for non-hardenable aluminium alloys2007In: Computational materials science, ISSN 0927-0256, E-ISSN 1879-0801, Vol. 41, no 1, p. 86-95Article in journal (Refereed)
    Abstract [en]

    A range of mechanical properties have been investigated for non-hardenable aluminium alloys. Commercially pure aluminium, Al-Mn, and Al-Mg alloys in five tempers have been covered. In the models solid solution, particle strengthening and work hardening have been taken into account. Ab-initio calculations of the size and modulus misfit parameters that are needed in the solid solution hardening model have been performed. In accordance with the Labusch-Nabarro model, the solid solution hardening has been shown to be proportional to εL4 / 3 c2 / 3, where εL is the Fleischer misfit parameter and c the solute concentration. A cold work parameter H has been introduced. The contribution from cold working is linear in H for the tensile strength and fatigue endurance, whereas the contributions to the yield strength and to the hardness are proportional to H0.5.

  • 124167.
    Zander, T.
    et al.
    Helmholtz Zentrum Geesthacht, Geesthacht, Germany..
    Wieland, F.
    Helmholtz Zentrum Geesthacht, Geesthacht, Germany..
    Wang, M
    KTH.
    Raj, A
    KTH.
    Claesson, P
    KTH.
    Dedinaite, A
    KTH.
    Haramus, V.
    Helmholtz Zentrum Geesthacht, Geesthacht, Germany..
    Schreyer, A.
    Helmholtz Zentrum Geesthacht, Geesthacht, Germany..
    Willumeit-Roemer, R.
    Helmholtz Zentrum Geesthacht, Geesthacht, Germany..
    XRR studies of the interaction of DPPC and hyaluronan at high hydrostatic pressure2015In: European Biophysics Journal, ISSN 0175-7571, E-ISSN 1432-1017, Vol. 44, p. S137-S137Article in journal (Other academic)
  • 124168.
    Zander, Thomas
    et al.
    Helmholtz Zentrum Geesthacht, Ctr Mat & Costal Res, Inst Mat Res, Max Planck Str 1, D-21502 Geesthacht, Germany..
    Wieland, D. C. Florian
    Helmholtz Zentrum Geesthacht, Ctr Mat & Costal Res, Inst Mat Res, Max Planck Str 1, D-21502 Geesthacht, Germany..
    Raj, Akanksha
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Salmen, Paul
    TU Dortmund, DELTA, Fak Phys, D-44221 Dortmund, Germany..
    Dogan, Susanne
    TU Dortmund, DELTA, Fak Phys, D-44221 Dortmund, Germany..
    Dédinaité, Andra
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. RISE Res Inst Sweden, Div Biosci & Mat, SE-11486 Stockholm, Sweden..
    Garamus, Vasil M.
    Helmholtz Zentrum Geesthacht, Ctr Mat & Costal Res, Inst Mat Res, Max Planck Str 1, D-21502 Geesthacht, Germany..
    Schreyer, Andreas
    Helmholtz Zentrum Geesthacht, Ctr Mat & Costal Res, Inst Mat Res, Max Planck Str 1, D-21502 Geesthacht, Germany..
    Claesson, Per M.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. RISE Res Inst Sweden, Div Biosci & Mat, SE-11486 Stockholm, Sweden..
    Willumeit-Roemer, Regine
    Helmholtz Zentrum Geesthacht, Ctr Mat & Costal Res, Inst Mat Res, Max Planck Str 1, D-21502 Geesthacht, Germany..
    Influence of high hydrostatic pressure on solid supported DPPC bilayers with hyaluronan in the presence of Ca2+ ions2019In: Soft Matter, ISSN 1744-683X, E-ISSN 1744-6848, Vol. 15, no 36, p. 7295-7304Article in journal (Refereed)
    Abstract [en]

    The molecular mechanisms responsible for outstanding lubrication of natural systems, like articular joints, have been the focus of scientific research for several decades. One essential aspect is the lubrication under pressure, where it is important to understand how the lubricating entities adapt under dynamic working conditions in order to fulfill their function. We made a structural investigation of a model system consisting of two of the molecules present at the cartilage interface, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine and hyaluronan, at high hydrostatic pressure. Phospholipid layers are found at the cartilage surfaces and are able to considerably reduce friction. Their behavior under load and varied solution conditions is important as pressures of 180 bar are encountered during daily life activities. We focus on how divalent ions, like Ca2+, affect the interaction between DPPC and hyaluronan, as other investigations have indicated that calcium ions influence their interaction. It could be shown that already low amounts of Ca2+ strongly influence the interaction of hyaluronan with DPPC. Our results suggest that the calcium ions increase the amount of adsorbed hyaluronan indicating an increased electrostatic interaction. Most importantly, we observe a modification of the DPPC phase diagram as hyaluronan absorbs to the bilayer which results in an L-alpha-like structure at low temperatures and a decoupling of the leaflets forming an asymmetric bilayer structure.

  • 124169. Zander, Thomas
    et al.
    Wieland, D. C. Florian
    Raj, Akanksha
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Wang, Min
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Nowak, Benedikt
    Krywka, Christina
    Dédinaité, Andra
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. SP Tech Res Inst Sweden.
    Claesson, Per Martin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. SP Tech Res Inst Sweden.
    Garamus, Vasil M.
    Schreyer, Andreas
    Willumeit-Romer, Regine
    The influence of hyaluronan on the structure of a DPPC-bilayer under high pressures2016In: Colloids and Surfaces B: Biointerfaces, ISSN 0927-7765, E-ISSN 1873-4367, Vol. 142, p. 230-238Article in journal (Refereed)
    Abstract [en]

    The superior lubrication properties of synovial joints have inspired many studies aiming at uncovering the molecular mechanisms which give rise to low friction and wear. However, the mechanisms are not fully understood yet, and, in particular, it has not been elucidated how the biolubricants present at the interface of cartilage respond to high pressures, which arise during high loads of joints. In this study we utilize a simple model system composed of two biomolecules that have been implied as being important for joint lubrication. It consists of a solid supported dipalmitoylphosphatidylcholin (DPPC) bilayer, which was formed via vesicles fusion on a flat Si wafer, and the anionic polysaccharide hyaluronan (HA). We first characterized the structure of the HA layer that adsorbed to the DPPC bilayers at ambient pressure and different temperatures using X-ray reflectivity (XRR) measurements. Next, XRR was utilized to evaluate the response of the system to high hydrostatic pressures, up to 2 kbar (200 MPa), at three different temperatures. By means of fluorescence microscopy images the distribution of DPPC and HA on the surface was visualized. Our data suggest that HA adsorbs to the headgroup region that is oriented towards the water side of the supported bilayer. Phase transitions of the bilayer in response to temperature and pressure changes were also observed in presence and absence of HA. Our results reveal a higher stability against high hydrostatic pressures for DPPC/HA composite layers compared to that of the DPPC bilayer in absence of HA.

  • 124170.
    Zander, Zachary K.
    et al.
    University of Akron, United States.
    Hua, Geng
    University of Akron, United States.
    Wiener, Clinton G.
    University of Akron, United States.
    Vogt, Bryan D.
    University of Akron, United States.
    Becker, Matthew L.
    University of Akron, United States.
    Control of Mesh Size and Modulus by Kinetically Dependent Cross-Linking in Hydrogels2015In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, p. n/a-n/aArticle in journal (Refereed)
    Abstract [en]

    Kinetically controlled cross-linking processes produce mechanically distinguishable hydrogels using identical precursor chemistry. The oxime ligation demonstrates tunable reaction kinetics with pH and buffer strength, which induce changes in the structural features of hydrogels and determine their mechanical properties. Small-angle neutron scattering and swelling studies provide an insight into how structural properties correlate with mechanical properties for this hydrogel system.

  • 124171.
    Zandi Shafagh, Reza
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Development and fabrication of OSTE and OSTE+ cartridges for the integration of quartz crystal microbalance biosensors2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The introduction of lab-on-a chip (LOC) devices introduced hopes of more advanced and rapid point-of-care diagnostics and pathogen detection, especially when used in combination with miniature and sensitive biosensors. Nevertheless, the commercialization of such devices has been limited, partly due to issues in achieving a facile and economically viable packaging using cost-effective materials. Newly developed thermosetting polymers address some of the issues by offering industry like material properties (i.e. thermoplastics) along with straight-forward back-end processing, e.g. adaptable surface modification and low temperature dry-bonding. Thus, such polymers have a great potential to be used for the fabrication of LOC-devices with integrated biosensors.

    In this thesis project, a novel approach for the integration and packaging of quartz crystal microbalance (QCM) biosensor chips, aimed for Norovirus detection, has been developed. The work initially evaluates the properties of novel thermosetting polymers for LOC cartridge applications. The study continues with an investigation of new polymer formulations, which features more favorable material properties and versatile back-end processing compared to standard OSTE. Lastly, microfluidic cartridges based on a novel thermosetting polymer were successfully fabricated and integrated with a gold-coated quartz crystal. The bond interfaces were homogenous, void-free and leak-tight. The devices were successfully tested in terms of noise, drift and response in a flow-through setting and upon exposure of bovine serum albumin protein.

  • 124172.
    Zandi Shafagh, Reza
    KTH, School of Electrical Engineering and Computer Science (EECS), Micro and Nanosystems.
    Thiol-ene Nanostructuring2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Improving the health and well-being of humankind does not only constitute

    part of our moral codes, but is also enlisted as the number three goal of

    the 2030 agenda for sustainable development set by the UN. Fulfilling such

    objective in the regions of resource-poor settings or for age groups with more

    vulnerability to infectious agents demands immediate actions. This has necessitated

    novel ways of rapid and ultra-sensitive diagnostics to provide compact

    and affordable systems, e.g. for an early detection of bacteria and viruses.

    The fields of bio-micro/nanoelectromechanical systems (BioMEMS/NEMS)

    and lab-on-a-chip (LoC) have been founded based on such demands, but

    critically challenged by problems partly associated with manufacturing and

    material domains and biosensing methods. The fabrication methods for the

    miniaturization of features and components are often complicated and expensive,

    the commonly used materials are typically not adaptable to industrial

    settings, and the sensing mechanisms are sometimes not sensitive enough for

    the detection of lowly-concentrated samples.

    In this thesis, new methods of ultra-miniaturization, as well as conventional

    cleanroom-based techniques, for nanopatterning of well-defined topographies

    in off-stoichiometry thiol-ene-(epoxy) polymers are presented. In addition,

    their use for several sensing applications has been demonstrated. The

    first part of the thesis gives an introduction to the field of BioMEMS/NEMS.

    The second part of the thesis presents a technical background about the

    prevalent methods of polymer micro- and nanofabrication, implementation

    of the resulting polymer structures for different sensing applications, along

    with the existing challenges and shortcomings associated with state of the

    art. The third part of the thesis presents e-beam nanostructuring of thiol-ene

    resist, for the first time, achieving the smallest and densest features reported

    in these polymer networks. The thiol-ene-based polymer also represents a

    novel class of e-beam resist resulting in structures with reactive surface nature.

    The fourth part of the thesis demonstrates the use of thiol-ene-epoxy

    systems for nanoimprint lithography and further shows the structuring of

    high-aspect-ratio and hierarchical topologies via single-step UV-NIL. The fifth

    part of the thesis introduces Micro- and NanoRIM platforms for scalable and

    off-cleanroom manufacturing of microfluidic devices and nanostructuring of

    materials in thiol-ene (-epoxy) systems. The sixth part of the thesis exhibits

    the implementation of the noted nanofabrication methods for different

    BioMEMS/NEMS applications including protein nanopatterning, simultaneous

    molding and surface energy patterning, ultra-sensitive digital biosensing,

    and facile quartz crystal microbalance (QCM) sensor packaging.

  • 124173.
    Zandi Shafagh, Reza
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Micro and Nanosystems.
    Decrop, Deborah
    Ven, Karen
    Vanderbeke, Arno
    Hanusa, Robert
    Breukers, Jolien
    Pardon, Gaspard
    Haraldsson, Klas Tommy
    KTH, School of Electrical Engineering and Computer Science (EECS), Micro and Nanosystems.
    Lammertyn, Jeroen
    van der Wijngaart, Wouter
    KTH, School of Electrical Engineering and Computer Science (EECS), Micro and Nanosystems.
    Reaction Injection Molding of Hydrophilic-in-Hydrophobic Femtolitre-Well Arrays2019In: Microsystems & Nanoengineering, E-ISSN 2055-7434, no 5, article id 25Article in journal (Refereed)
    Abstract [en]

    Patterning of micro- and nanoscale topologies and surface properties of polymer devices is of particular importance for a broad range of life science applications, including cell-adhesion assays and highly sensitive bioassays. The manufacturing of such devices necessitates cumbersome multiple-step fabrication procedures and results in surface properties which degrade over time. This critically hinders their wide-spread dissemination. Here, we simultaneously mold and surface energy pattern microstructures in off-stoichiometric thiol-ene by area-selective monomer self-assembly in a rapid micro-reaction injection molding cycle. We replicated arrays of 1,843,650 hydrophilic-in-hydrophobic femtolitre-wells with long-term stable surface properties and magnetically trapped beads with 75% and 87.2% efficiency in single- and multiple-seeding events, respectively. These results form the basis for ultrasensitive digital biosensors, specifically, and for the fabrication of medical devices and life science research tools, generally.

  • 124174.
    Zandi Shafagh, Reza
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Micro and Nanosystems.
    Guo, Weijin
    KTH, School of Electrical Engineering and Computer Science (EECS), Micro and Nanosystems.
    van der Wijngaart, Wouter
    KTH, School of Electrical Engineering and Computer Science (EECS), Micro and Nanosystems.
    Haraldsson, Klas Tommy
    KTH, School of Electrical Engineering and Computer Science (EECS), Micro and Nanosystems.
    Bio-Inspired High-Aspect-Ratio and Hierarchical Nanoimprint LithographyManuscript (preprint) (Other academic)
  • 124175.
    Zandi Shafagh, Reza
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    van der Wijngaart, Wouter
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Haraldsson, Tommy
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    NanoRIM: Sub-micron Structuring with Reaction Injection Molding2017In: 2017 IEEE 30th International Conference on Micro Electro Mechanical Systems (MEMS), Institute of Electrical and Electronics Engineers (IEEE), 2017Conference paper (Refereed)
    Abstract [en]

      We report “nanoRIM”, the first reaction injection molding (RIM) replication method for thermosets with demonstrated feature sizes down to 250 nm. NanoRIM constitutes the first scalable manufacturing method for thermoset polymers that allows combining large (> cm) and small (< μm) lateral feature sizes with varying replica thickness in the same device. We demonstrate nanoRIM for manufacturing replica in off-stoichiometry thiol-ene (OSTE) thermoset.

  • 124176.
    Zandian, Arash
    KTH, School of Biotechnology (BIO).
    A pilot study using antigen microarrays to identify putative autoimmunity targets in psychiatric disorders2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 124177.
    Zandian, Arash
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Array-based Autoantibody Profiling and Epitope Mapping2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Antibodies are a class of proteins that are made by the immune system to recognize harmful organisms and molecules. Their exceptional capability of specifically recognizing molecules has been investigated for over a century and information thereof has been utilized for a variety of applications including vaccine and generation of therapeutic antibodies. Occasionally, instead of protecting the host against pathogens, antibodies can recognize constituents of the host and thereby cause an autoimmune reaction that eventually can lead to a disease. Therefore, it is of great interest to understand what the antibodies bind to and their specificities.

     

    The last decades of technical development and availability of protein and peptide microarrays have enabled large-scale profiling of antibodies and precise determination of their specificities through epitope mapping. In this thesis the aim was to use affinity proteomics tools to profile antibodies, determine their specificities, and discover potential associations of autoantigens to disease by analyzing blood-derived samples with microarray-based methods.

     

    In Paper I, 57 serum samples from patients with the suggested autoimmune disease narcolepsy, were analyzed on planar antigen microarrays with 10,846 human protein fragments. Verification on an independent sample collection consisting of serum samples from 176 individuals, revealed METTL22 and NT5C1A as two potential autoantigens. In Paper II, antibodies from 53 plasma samples from patients with first-episode psychosis, a condition suggested to have a partial autoimmune component, were analyzed on planar antigen microarrays with 2,304 human protein fragments. After a follow-up study of the patients, antibodies toward an antigen representing the three proteins, PAGE2, PAGE2B, PAGE5, was found associated to an increased risk of developing schizophrenia. In Paper III, serum and plasma samples from patients with the autoimmune diseases multiple sclerosis and narcolepsy, were epitope mapped on high-density peptide microarrays with approximately 2.2 million peptides. Technical and biological verification, by using other microarray technology and analyzing  samples from 448 patients, revealed one peptide for multiple sclerosis and narcolepsy, representing the proteins MAP3K7 and NRXN1, with higher antibody reactivity towards in each group, respectively. In Paper IV, purified polyclonal antibodies raised against a surface antigen found on malaria-infected erythrocytes, were profiled on the peptide microarrays representing all proteins found on malaria-infected erythrocytes derived from Plasmodium falciparum. Then, different Plasmodium falciparum strains were analyzed by immunofluorescence microscopy and western blots, using the epitope mapped antibodies. The performance of the immunoassays were compared to the identified epitopes, and validated by RNA sequencing.

     

    In conclusion, these investigations describe multiplex methods to identify and characterize antibodies, their disease association and epitopes. Follow-up studies are needed to determine their potential use and clinical value.

  • 124178.
    Zandian, Arash
    et al.
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Forsström, Björn
    KTH, School of Biotechnology (BIO), Centres, Albanova VinnExcellence Center for Protein Technology, ProNova. KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Häggmark-Månberg, Anna
    Schwenk, Jochen M.
    KTH, School of Biotechnology (BIO), Proteomics (closed 20130101). KTH, School of Biotechnology (BIO), Nano Biotechnology (closed 20130101). KTH, Centres, Science for Life Laboratory, SciLifeLab. KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology.
    Uhlén, Mathias
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology.
    Nilsson, Peter
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Ayoglu, Burcu
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Whole-Proteome Peptide Microarrays for Profiling Autoantibody Repertoires within Multiple Sclerosis and Narcolepsy2017In: Journal of Proteome Research, ISSN 1535-3893, E-ISSN 1535-3907, Vol. 16, no 3, p. 1300-1314Article in journal (Refereed)
    Abstract [en]

    The underlying molecular mechanisms of autoimmune diseases are poorly understood. To unravel the autoimmune processes across diseases, comprehensive and unbiased analyses of proteins targets recognized by the adaptive immune system are needed. Here we present an approach starting from high-density peptide arrays to characterize autoantibody repertoires and to identify new autoantigens. A set of ten plasma and serum samples from subjects with multiple sclerosis, narcolepsy, and without any disease diagnosis were profiled on a peptide array representing the whole proteome, hosting 2.2 million 12-mer peptides with a six amino acid lateral shift. On the basis of the IgG reactivities found on these whole-proteome peptide micro arrays, a set of 23 samples was then studied on a targeted array with 174 000 12-mer peptides of single amino acid lateral shift. Finally, verification of IgG reactivities was conducted with a larger sample set (n = 448) using the bead-based peptide microarrays. The presented workflow employed three different peptide microarray formats to discover and resolve the epitopes of human autoantibodies and revealed two potentially new autoantigens: MAP3K7 in multiple sclerosis and NRXN1 in narcolepsy. The presented strategy provides insights into antibody repertoire reactivity at a peptide level and may accelerate the discovery and validation of autoantigens in human diseases.

  • 124179.
    Zandian, Arash
    et al.
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Wingård, L.
    Nilsson, H.
    Sjöstedt, E.
    Johansson, D. X.
    Just, David
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Hellström, Cecilia
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Uhlén, Mathias
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Schwenk, Jochen M.
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Häggmark-Månberg, Anna
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Norbeck, O.
    Owe-Larsson, B.
    Nilsson, Peter
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Persson, M. A. A.
    Untargeted screening for novel autoantibodies with prognostic value in first-episode psychosis2017In: Translational Psychiatry, ISSN 2158-3188, E-ISSN 2158-3188, Vol. 7, article id e1177Article in journal (Refereed)
    Abstract [en]

    Immunological and inflammatory reactions have been suggested to have a role in the development of schizophrenia, a hypothesis that has recently been supported by genetic data. The aim of our study was to perform an unbiased search for autoantibodies in patients with a first psychotic episode, and to explore the association between any seroreactivity and the development of a Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV) disorder characterized by chronic or relapsing psychotic symptoms. We collected plasma samples from 53 patients when they were treated for their first-episode psychosis, and 41 non-psychotic controls, after which the patients were followed for a mean duration of 7 years. Thirty patients were diagnosed with schizophrenia, delusional disorder, schizoaffective disorder, bipolar disorder or a long-term unspecified nonorganic psychosis during follow-up, whereas 23 patients achieved complete remission. At the end of follow-up, plasma samples were analyzed for IgG reactivity to 2304 fragments of human proteins using a multiplexed affinity proteomic technique. Eight patient samples showed autoreactivity to the N-terminal fragment of the PAGE (P antigen) protein family (PAGE2B/PAGE2/PAGE5), whereas no such autoreactivity was seen among the controls. PAGE autoreactivity was associated with a significantly increased risk of being diagnosed with schizophrenia during follow-up (odds ratio 6.7, relative risk 4.6). An immunohistochemistry analysis using antisera raised against the N-terminal fragment stained an unknown extracellular target in human cortical brain tissue. Our findings suggest that autoreactivity to the N-terminal portion of the PAGE protein family is associated with schizophrenia in a subset of patients with first-episode psychosis.

  • 124180.
    Zandieh, Behdis
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Indoor Wireless Local Area Network (WLAN): Measurement and Modeling from a user perspective2007Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    If we had detailed wireless local area network (WLAN) coverage maps, both staff and equipment could be used more efficiently, for example, less time would be spent searching for connectivity. In addition, system administrators could understand their WLAN's utilization better, thus enabling better planning for where to install new access points, where to remove access points, where to change the type of antenna, etc. This thesis concerns creating detailed indoor coverage models by using measured network performance - in order to enable both users and administrators to visualize the network coverage. Today a user can only easily know about the access points that they currently hear – in the location where they currently are. Giving the users and administrators access to a model of the entire campus coverage will allow them to understand not only the _local_ coverage, but the patterns of coverage (or lack there of). However, no efficient modeling techniques are currently available for those deploying and operating indoor WLANs.

    The thesis begins with some general background information and then examines a number of WLAN survey tools; in terms of both their performance and cost. Following this a number of related projects are presented. This background provides the motivation for why a new tool is needed and what functions such a tool should have.

    Next a site survey of the KTH campus in Kista was conducted using a newly developed survey application. This application was developed to better meet the requirements derived from the missing functionality of existing tools. In addition, developing this application gave the author an opportunity to learn a new objectoriented programming language, i.e. C# and the .NET environment. Learning to use this new environment was essential to building both an easy to use application and collecting the data from the system - the later was often not straight-forward.

    ne of the key issues after data collection is how to present the collected data to the user and how this varies depending upon the user’s interests and task. An initial representation of the experimental data is presented as a manually painted coverage map overlayed onto a map. Next the thesis examines how to integrate the experimental data using Google’s SketchUp in order to build a 3D model of the WLAN coverage on this campus.

    Future work related to this thesis should focus on how to automate the collection of data and how to automate the presentation of the resulting experimental data.

  • 124181. Zane, Silvia
    et al.
    Winter, Berend
    Theobald, Craig
    Theodorou, Theodorus
    Pinchera, Michele
    Muleri, Fabio
    Spada, Francesca
    Sgro, Carmelo
    Zanetti, Davide
    Feng, Hua
    del Monte, Ettore
    Rubini, Alda
    Soffitta, Paolo
    Bellazzini, Ronaldo
    Bozzo, Enrico
    Burwitz, Vadim
    Castro Tirado, Alberto J.
    Costa, Enrico
    Gburek, Szymon
    Goosmann, Rene
    Karas, Vladimir
    Matt, Giorgio
    Nandra, Kirpal
    Pearce, Mark
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Poutanen, Juri
    Reglero, Victor
    Dolores Sabau, Maria
    Santangelo, Andrea
    Tagliaferri, Giampiero
    Tenzer, Christopher
    Vink, Jacco
    Weisskopf, Martin
    The on-board calibration system of the X-ray Imaging Polarimetry Explorer (XIPE)2016In: SPACE TELESCOPES AND INSTRUMENTATION 2016: ULTRAVIOLET TO GAMMA RAY, SPIE - International Society for Optical Engineering, 2016, article id UNSP 99054HConference paper (Refereed)
    Abstract [en]

    The calibration system for XIPE is aimed at providing a way to check and correct possible variations of performance of the Gas Pixel Detector during the three years of operation in orbit (plus two years of possible extended operation), while facilitating the observation of the celestial sources. This will be performed by using a filter wheel with a large heritage having a set of positions for the calibration and the observation systems. In particular, it will allow for correcting possible gain variation, for measuring the modulation factor using a polarized source, for removing non interesting bright sources in the field of view and for observing very bright celestial sources. The on-board calibration system is composed of three filter wheels, one for each detector and it is expected to operate for a small number of times during the year. Moreover, since it operates once at a time, within the observation mode, it allows for simultaneous calibration and acquisition from celestial sources on different detectors. In this paper we present the scope and the requirements of the on-board calibration system, its design, and a description of its possible use in space.

  • 124182. Zanella, F.
    et al.
    Varagnolo, Damiano
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Cenedese, A.
    Pillonetto, G.
    Schenato, L.
    Asynchronous Newton-Raphson Consensus for distributed convex optimization2012In: Estimation and Control of Networked Systems: Volume 3, Part 1, 2012, p. 133-138Conference paper (Refereed)
    Abstract [en]

    We consider the distributed unconstrained minimization of separable convex cost functions, where the global cost is given by the sum of several local and private costs, each associated to a specific agent of a given communication network. We specifically address an asynchronous distributed optimization technique called Newton-Raphson Consensus. Beside having low computational complexity, low communication requirements and being interpretable as a distributed Newton-Raphson algorithm, the technique has also the beneficial properties of requiring very little coordination and naturally supporting time-varying topologies. In this work we analytically prove that under some assumptions it shows either local or global convergence properties, and corroborate this result by the means of numerical simulations.

  • 124183.
    Zanello, Fabrizio
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.).
    Improving the bounds of the multiplicity conjecture: The codimension 3 level case2007In: Journal of Pure and Applied Algebra, ISSN 0022-4049, E-ISSN 1873-1376, Vol. 209, no 1, p. 79-89Article in journal (Refereed)
    Abstract [en]

    The Multiplicity Conjecture (MC) of Huneke and Srinivasan provides upper and lower bounds for the multiplicity of a Cohen-Macaulay algebra A in terms of the shifts appearing in the modules of the minimal free resolution (MFR) of A. All the examples studied so far have lead to conjecture (see [J. Herzog, X. Zheng, Notes on the multiplicity conjecture. Collect. Math. 57 (2006) 211-226] and [J. Mighore, U. Nagel, T. Romer, Extensions of the multiplicity conjecture, Trans. Amer. Math. Soc. (preprint: math. AC/0505229) (in press)]) that, moreover, the bounds of the MC are sharp if and only if A has a pure MFR. Therefore, it seems a reasonable - and useful - idea to seek better, if possibly ad hoc, bounds for particular classes of Cohen-Macaulay algebras. In this work we will only consider the codimension 3 case. In the first part we will stick to the bounds of the MC, and show that they hold for those algebras whose h-vector is that of a compressed algebra. In the second part, we will (mainly) focus on the level case: we will construct new conjectural upper and lower bounds for the multiplicity of a codimension 3 level algebra A, which can be expressed exclusively in terms of the h-vector of A, and which are better than (or equal to) those provided by the MC. Also, our bounds can be sharp even when the MFR of A is not pure. Even though proving our bounds still appears too difficult a task in general, we are already able to show them for some interesting classes of codimension 3 level algebras A: namely, when A is compressed, or when its h-vector h(A) ends with (.., 3, 2). Also, we will prove our lower bound when h(A) begins with (1, 3, h,), where h(2) : 4, and our upper bound when h (A) ends with (.... h(c-1), h(c)), where h(c-1) < h(c) + 1.

  • 124184.
    Zanello, Fabrizio
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.).
    The h-vector of a relatively compressed level algebra2007In: Communications in Algebra, ISSN 0092-7872, E-ISSN 1532-4125, Vol. 35, no 4, p. 1087-1091Article in journal (Refereed)
    Abstract [en]

    The purpose of this note is to supply an upper and a lower bound (which are in general sharp) for the h-vector of a level algebra which is relatively compressed with respect to any arbitrary level algebra A. The useful concept of relatively compressed algebra was recently introduced in Migliore et al. (2005) (whose investigations mainly focused on the particular case of A a complete intersection). The key idea of this note is the simple observation that the level algebras which are relatively compressed with respect to A coincide (after an obvious isomorphism) with the generic level quotients of suitable truncations of A. Therefore, we are able to apply to relatively compressed algebras the main result of our recent work, Zanello (2007).

  • 124185. Zanette, I.
    et al.
    Zdora, M. -C
    Zhou, Tunhe
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Burvall, Anna
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Larsson, Daniel H.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Thibault, P.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Pfeiffer, F.
    X-ray microtomography using correlation of near-field speckles for material characterization2015In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 112, no 41, p. 12569-12573Article in journal (Refereed)
    Abstract [en]

    Nondestructive microscale investigation of objects is an invaluable tool in life and materials sciences. Currently, such investigation is mainly performed with X-ray laboratory systems, which are based on absorption-contrast imaging and cannot access the information carried by the phase of the X-ray waves. The phase signal is, nevertheless, of great value in X-ray imaging as it is complementary to the absorption information and in general more sensitive to visualize features with small density differences. Synchrotron facilities, which deliver a beam of high brilliance and high coherence, provide the ideal condition to develop such advanced phase-sensitive methods, but their access is limited. Here we show how a small modification of a laboratory setup yields simultaneously quantitative and 3D absorption and phase images of the object. This single-shot method is based on correlation of X-ray near-field speckles and represents a significant broadening of the capabilities of laboratory- based X-ray tomography.

  • 124186. Zanette, I.
    et al.
    Zhou, Tunhe
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Burvall, Anna
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Lundström, Ulf
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Larsson, Daniel H.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Zdora, M.
    Thibault, P.
    Pfeiffer, F.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Speckle-Based X-Ray Phase-Contrast and Dark-Field Imaging with a Laboratory Source2014In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 112, no 25, p. 253903-Article in journal (Refereed)
    Abstract [en]

    We report on the observation and application of near-field speckles with a laboratory x-ray source. The detection of speckles is possible thanks to the enhanced brilliance properties of the used liquid-metal-jet source, and opens the way to a range of new applications in laboratory-based coherent x-ray imaging. Here, we use the speckle pattern for multimodal imaging of demonstrator objects. Moreover, we introduce algorithms for phase and dark-field imaging using speckle tracking, and we show that they yield superior results with respect to existing methods.

  • 124187. Zang, A.
    et al.
    Stephansson, Ove
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630). GFZ German Research Centre for Geosciences, Telegrafenberg, Germany .
    Stress field of the earth's crust2010Book (Refereed)
    Abstract [en]

    This book about rock stress is suitable for students in geosciences and rock engineering, who need to broaden their horizons about the Stress Field of the Earth?s Crust. The book covers the topic so that geosciences students will be able to grasp the Cauchy Stress Principle without fear of matrix transformations in an exercise. Students interested in mathematics, physics and engineering will learn how strain gauges are used to obtain in-situ stress by the overcoring method. Leading edge technology in determining rock stress like quadruple packer and the Kaiser effect are presented together with classical methods like hydraulic fracturing. Borehole techniques (breakouts) and core-based methods (anelastic strain recovery) are illustrated. With respect to stress data, we choose to present the scientific ultra-deep drilling project KTB (Germany), the excavation for nuclear waste disposal at Olkiluoto (Finland) and the drilling into a seismic active fault zone at SAFOD (USA). Stress compilations viewed by the World Stress Map project are presented and interpreted in terms of plate tectonics.

  • 124188. Zang, A.
    et al.
    Stephansson, Ove
    Dresen, G.
    Rock damage and fluid transport: Part 22006In: Pure and Applied Geophysics, ISSN 0033-4553, E-ISSN 1420-9136, Vol. 163, no 10, p. 2049-2050Article in journal (Refereed)
  • 124189.
    Zang, Kristina
    KTH, School of Industrial Engineering and Management (ITM), Industrial Ecology.
    Analys av miljöaspekter för en planerad svensk fabrik i Kina2006Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A Swedish company, company F, will establish a new factory in China. Company F is adivision within Company F. The factory in China will manufacture wire products. Thepurpose of this final thesis is to analyse which legal and practical measures the company hasto undertake during the process of localization to get approval from the Chineseenvironmental legislation.An analysis of the influencing factors on the environment from the production in theconstruction in Sweden was carried through. A material-balance was analysed according tothe flowchart of the production. Since China is still considered a developing country, it is alsostill a lot different from Sweden, but it is changing rapidly. Most of the environmental lawsthat were studied are parts of the legal framework, which means that no exact limits ordetailed guidelines are given. The company brings its cutting-edge technology, which still isnew and unknown to the industrial park in China. Therefore it is too early to decide whethercompany F complies with the local jurisdiction in China. The company will make a thoroughreport on its future production to EPA, the Environmental Protection Agency, when theyapply for a license for the factory. In the report they can describe the production in Swedenand compare it to its possible production in China. By presenting the demands andrequirements of the EPA in Sweden given to company F by regard to its Swedish business, itcan help the EPA in China getting a better idea about the production and to what extentdischarge and contamination from the factory will affect the environment. To be able to planfor the long run and make the production meet the environmental standards in China, thefactory must use Swedish standards from the beginning.Two industrial parks in China were visited, one in Suzhou and the other in Wuxi. From anenvironmental perspective, both of the locations are good options for company F since bothare high-qualitative industrial parks that already exist. Suzhou is closer to Shanghai and hasits own Customs, which will benefit the company. There are companies, approved by theindustrial park and the EPA, that take care of waste. They collect the waste from the factory,and send some parts to a recycling factory. After the process of recycling, it is once againdelivered to the factories to produce e.g. new paper- or plastic-products. The rest of the toxicwaste is sent to other places for storage, disposal and destruction. Some toxic waste collectedfrom the factory undergoes a special process.When company F establishes its factory in China they should pay extra attention to whichlocation to choose and also which material of construction to use in order to avoid the hazardof fire. The lay-out must be thoroughly planned – e.g. where the fire exits should be. It isimperative that education about processing and environment be given continuously. Theinformation must reach the staff on all levels. The company must improve the technique allthe time, and look for the best possible technique available. Discharge in air or water must bemeasured regularly, according to the standards of the local authorities. The inspections of theplant must also take place regularly.

  • 124190. Zang, W.
    et al.
    Gudmundson, Peter
    KTH, Superseded Departments, Solid Mechanics.
    Damage Evolution and Thermoelastic Properties of Composite Laminates1993In: International journal of damage mechanics, ISSN 1056-7895, E-ISSN 1530-7921, Vol. 2, p. 290-308Article in journal (Refereed)
    Abstract [en]

    An analytic model for the prediction of the thermoelastic properties of micro cracked composite laminates is presented. The expression for the calculation of en ergy release rates due to growth of micro cracks is also provided. Numerical results are presented that show that the present method, to a very good accuracy, can predict ther moelastic properties of micro cracked laminates at varying crack densities and layup con figurations. In addition, a resistance curve behavior of the energy release rate is observed for both carbon/epoxy and glass/epoxy composite laminates. The reasons for this R-curve behavior are discussed. Criteria that govern the initiation and growth of micro cracks in composite laminates are discussed and compared to experimental data.

  • 124191.
    Zang, Weilin
    et al.
    KTH, Superseded Departments, Solid Mechanics.
    Gudmundson, Peter
    KTH, Superseded Departments, Solid Mechanics.
    A Boundary Integral Method For Internal Piece-Wise Smooth Crack Problems1988In: International Journal of Fracture, ISSN 0376-9429, E-ISSN 1573-2673, Vol. 38, no 4, p. 275-294Article in journal (Refereed)
    Abstract [en]

    A new boundary integral method for plane elasticity problems with internal piece-wise smooth cracksis presented. The method can be applied to both infinite and finite geometries. A numerical technique which combines a collocation method for the cracks and the standard BEM technique for the outer boundary is used to solve the integral equations. Numerical examples are presented and compared either to existing solutions or to FEM calculations. All of the results provided by the present method are shown to be very accurate for both smooth and kinked cracks in both finite and infinite geometries.

  • 124192.
    Zang, Weilin
    et al.
    KTH, Superseded Departments, Solid Mechanics.
    Gudmundson, Peter
    KTH, Superseded Departments, Solid Mechanics.
    An Integral-Equation Method For Piece-Wise Smooth Cracks In An Elastic Half-Plane.1989In: Engineering Fracture Mechanics, ISSN 0013-7944, E-ISSN 1873-7315, Vol. 32, no 6, p. 889-897Article in journal (Refereed)
    Abstract [en]

    A boundary integral equation method for piece-wise smooth cracks in an elastic half-plane is presented. Both internal and surface cracks have been considered. The numerical formulation is based on an element description of the unknown dislocation densities along the crack line. Crack line kinks are treated by an introduction of double nodes at each kink. Numerical test examples are presented and compared, either to existing solutions, or to own finite element calculations. Excellent agreements were obtained for all cases.

  • 124193. Zang, W.L.
    et al.
    Gudmundson, Peter
    KTH, Superseded Departments, Solid Mechanics.
    An integral equation method based on resultant forces on a piece-wise smooth crack in a finite plate1989In: Proceedings of the 7th International Conference on Fracture (ICF7), Houston, Texas, 1989, p. 2127-2134Conference paper (Refereed)
  • 124194.
    Zang, W.L.
    et al.
    KTH, Superseded Departments, Solid Mechanics.
    Gudmundson, Peter
    KTH, Superseded Departments, Solid Mechanics.
    Contact Problems Of Kinked Cracks Modeled By A Boundary Integral Method1990In: International Journal for Numerical Methods in Engineering, ISSN 0029-5981, E-ISSN 1097-0207, Vol. 29, no 4, p. 847-860Article in journal (Refereed)
    Abstract [en]

    Based on the integral equation for the resultant forces along a crack, a numerical method is developed for the solution of two dimensional kinked crack problems taking crack contact into account. The method is demonstrated by a consideration of an elastic half-plane containing a piece-wise straight line crack. Two numerical examples are presented and compared to finite element calculations. The numerical results indicate that the present method can be an effective and reliable tool for investigations of kinked crack problems associated with crack contact.

  • 124195. Zang, W.L.
    et al.
    Gudmundson, Peter
    SICOMP, Swedish Institute of Compositie.
    Frictional Contact Problems Of Kinked Cracks Modeled By A Boundary Integral Method1991In: International Journal for Numerical Methods in Engineering, ISSN 0029-5981, E-ISSN 1097-0207, Vol. 31, no 3, p. 427-446Article in journal (Refereed)
    Abstract [en]

    A numerical method is presented for the solution of two dimensional crack problems including the effects of crack kinks and frictional contact between crack faces. The method is based on an integral equation for the resultant forces along a crack. Coulomb friction between contacting crack surfaces is taken into account. The numerical implementation is demonstrated by considerations of surface and sub-surface piece-wise straight line cracks in a half-plane. Numerical results are presented to illustrate the efficiency and the reliability of the presented method.

  • 124196.
    Zang, W.L.
    et al.
    KTH, Superseded Departments, Solid Mechanics.
    Gudmundson, Peter
    SICOMP, Swedish Institute of Composites.
    Kinked Cracks In An Anisotropic Plane Modeled By An Integral-Equation Method.1991In: International Journal of Solids and Structures, ISSN 0020-7683, E-ISSN 1879-2146, Vol. 27, no 14, p. 1855-1865Article in journal (Refereed)
    Abstract [en]

    A boundary integral method for cracks in an anisotropic material is presented. The method is based on the integral equation for the resultant forces along the cracks. The integral kernels contain only a weak logarithmic singularity, which simplifies the numerical implementation. Crack closure is also taken into account in the numerical formulation. Numerical tests are presented to illustrate the efficiency and the reliability of the proposed method.

  • 124197.
    Zang, W.L.
    et al.
    KTH, Superseded Departments, Solid Mechanics.
    Gudmundson, Peter
    KTH, Superseded Departments, Solid Mechanics.
    Kinked cracks in bonded half-planes modeled by an integral equation method1992In: International Journal of Fracture, ISSN 0376-9429, E-ISSN 1573-2673, Vol. 54, no 1, p. 65-78Article in journal (Refereed)
    Abstract [en]

    Based on the integral equation for resultant forces along a crack, a boundary integral equation method for the solution of kinked cracks in bonded half-planes is presented. The equation only contains a weak logarithmic singularity and is valid for every point along the crack lines. Numerical results are presented to illustrate the efficiency and reliability of the method.

  • 124198. Zang, W.L.
    et al.
    Gudmundson, Peter
    KTH, Superseded Departments, Solid Mechanics.
    On integral equation methods for kinked cracks1990Conference paper (Refereed)
  • 124199. Zangenah, S.
    et al.
    Andersson, Anders F.
    KTH, School of Biotechnology (BIO), Gene Technology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Ozenci, V.
    Bergman, P.
    Genomic analysis reveals the presence of a class D beta-lactamase with broad substrate specificity in animal bite associated Capnocytophaga species2017In: European Journal of Clinical Microbiology and Infectious Diseases, ISSN 0934-9723, E-ISSN 1435-4373, Vol. 36, no 4, p. 657-662Article in journal (Refereed)
    Abstract [en]

    Capnocytophga canimorsus and Capnocytophga cynodegmi can be transmitted from cats and dogs to humans, and can cause a wide range of infections including wound infections, sepsis, or endocarditis. We and others recently discovered two new Capnocytophaga species, C. canis and C. stomatis, mainly associated with wound infections. The first-line treatment of animal bite related infections is penicillin, and in case of allergy, doxycycline and trimethoprim/sulfamethoxazole. However, there is a lack of antibiotic susceptibility patterns for animal bite associated Capnocytophaga species. Thus, we i >> inverted question markset out to study the antibiotic profiles against animal bite associated Capnocytophaga species isolated from wound and blood cultures after cat and dog bites and coupled the findings to whole genome sequencing data. A total of 24 strains were included in the study. Phenotypic analysis of antibiotic resistance was performed with E-tests. The web-based tool 'Resfinder' was used to identify resistance genes in the whole genome dataset. Two strains of C. cynodegmi and two strains of the recently discovered C. stomatis were resistant to penicillin (MIC 24 mgi >> inverted question mark/L) and cephalosporins (MIC 24 mg/i >> inverted question markL), and three out of these strains also exhibited resistance to imipenem (MIC = 32 mg/i >> inverted question markL). Genomic analysis revealed that these strains carried a class D beta-lactamase gene, which has not previously been found in Capnocytophaga spp. A class D beta lactamase with broad substrate specificity was found in animal bite associated Capnocytophaga species, which could have important implications when treating wound infections after cat and dog bites. It also suggests that pet animal bacteria can harbour resistance genes with relevance for human infections.

  • 124200. Zangenah, Salah
    et al.
    Abbasi, Nasir
    Univ Miguel Hernandez,Spain.
    Andersson, Anders F.
    KTH, Centres, Science for Life Laboratory, SciLifeLab. KTH, School of Biotechnology (BIO), Gene Technology.
    Bergman, Peter
    Whole genome sequencing identifies a novel species of the genus Capnocytophaga isolated from dog and cat bite wounds in humans2016In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, article id 22919Article in journal (Refereed)
    Abstract [en]

    C. canimorsus and C. cynodegmi are dog and cat commensals which can be transmitted to humans via bites or scratches and can cause sepsis, meningitis, endocarditis, and eye- or wound infections. Recently an additional Capnocytophaga species was identified as part of the oral flora of healthy dogs and was given the name "C. canis". We previously identified a Capnocytophaga isolate that could not be typed with available diagnostic tests including MALDI-TOF, 16S rRNA sequencing or species-specific PCR. This strain and 21 other Capnocytophaga spp isolated in Sweden from clinical blood- or wound-cultures were subjected to whole genome sequencing using the Illumina platform. Phylogenetic analysis revealed that the previously non-typable isolate belongs to the putative new species "C. canis". Since this strain was isolated from a wound it also shows that members of "C. canis" have the potential to be pathogenic. In addition, our phylogenetic analysis uncovered an additional species of Capnocytophaga, which can be transmitted from dogs and cats to humans, suggesting a speciation within the Capnocytophaga family that has not been observed before. We propose the name of "C. stomatis" for this putative novel species.

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