| 1. |
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| 2. |
- Boman, Christoffer, et al.
(författare)
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Development of innovative small(micro)-scale biomass-based CHP technologies
- 2017
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- To enhance the overall efficiency of the use of biomass in the energy sector in Europe, the large electricity production potential from small-scale biomass heating systems should be utilised. So far, no technologically sound (in terms of efficiency and reliability) and economically affordable micro- and small-scale biomass CHP technologies are, however, available. Therefore, the present ERA-NET project (MiniBioCHP) aimed at the further development and test of new CHP technologies based on small-scale biomass combustion in the electric capacity range between some W and 100 kW. Within the project, an international consortium consisting of 12 partners from 4 countries, including university institutions, institutes and industry (both engineering and manufacturing), collaborated closely to perform high level R&D on three promising micro/small-scale biomass based CHP technologies which are covering a broad range of applications in the residential heating sector. The Austrian engineering company BIOS, coordinated the international project. The project was based on earlier basic research and development work related to these promising new technologies and aimed at the achievement of a technological level which allows a first (commercial) demonstration after the end of the project. The three CHP concepts included in the MiniBioCHP project were;1. Pellet stoves with a thermoelectric generator (TEG)2. Small-scale biomass boilers (10-30 kWth) with a micro-ORC process3. High temperature heat exchanger (HT-HE) for an externally fired gas turbine (EFGT)The Swedish part of the project was focused on the development of the concept of biomass based EFGT with dedicated R&D activities related to the development of the HT-HE system. The Swedish project consisted of the research partners Umeå University (project leader), Luleå University of Technology, Chalmers University of Technology and RISE Research Institutes of Sweden, together with the industrial partners Enertech AB/Osby Parca and Ecergy. The expertise of the Swedish partners regarding ash related problems, grate boiler combustion and modelling, deposit formation and high temperature corrosion, were combined with the know-how of a Polish partner regarding HT-HE design, construction, testing and optimisation.The HT-HE is the most crucial component in EFGT processes significantly influencing the investment costs, availabilities as well as the efficiencies that can be achieved. With a thermal capacity from several hundred kW up to 2-3 MWth) the CHP technology based on a biomass boiler and an EFGT is suitable for district heating systems, or process heat consumers. The electricity produced by the gas turbine (up to some 100 kWel) can be used to cover the own electricity consumption of a company and/or fed into the grid. Even though the concept of biomass based EFGT has been an interesting alternative for small-scale CHP production for some decades, and R&D activities have been undertaken, tackling both economic and technical aspects, only a few pilot-plants have been in operation and no initiative has so far reached the level of commercial implementation. Thus, the concept of EFGT fed with biomass is still considered to be in a rather early development stage and the main technical challenges are related to alkali deposit induced corrosion and thermal stress of the HT-HE material, turbine design/operation and system integration.Within the present project, a HT-HE prototype aimed for an EFGT system was therefore designed, constructed and successfully tested at flue gas temperatures up to 900°C. Thus, appropriate guidelines for a compact design of the HT-HE and recommendations have been worked out to minimize thermal stresses as well as ash related problems regarding ash deposit formation and high temperature corrosion in a biomass boiler system. Furthermore, different concepts for the overall biomass based EFGT system have been worked out and evaluated. The outcome of the project will hopefully be used in the further development work and form the basis for a first testing and demonstration plant within the coming years.
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| 3. |
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| 4. |
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| 5. |
- Boström, Anders E, 1951, et al.
(författare)
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Point-force excitation of an elastic plate with n embedded cavity
- 1985
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Ingår i: Journal of Applied Mechanics, Transactions ASME. - : ASME International. - 0021-8936 .- 1528-9036. ; 52:4, s. 937-942
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Tidskriftsartikel (refereegranskat)abstract
- The propagation of elastic waves in a thick plate containing an embedded cavity is considered. The full elastodynamic equations are solved and both time-harmonic and pulse propagation are treated. The time-harmonic problem is solved using the null field approach, a method whose main characteristics are surface integral representations and expansions in spherical and planar vector wave functions. To obtain the pulse response, a Fourier integral in frequency is employed. Numerical examples are given showing the fields in both the time and frequency domains at a few selectd locations on the plate surfaces when the plate is excited by a point force. Only low and intermediate frequencies are included and the pulse width is thus somewhat larger than the dimensions of the spheroidal cavity.
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| 6. |
- Brus, Elisabet, et al.
(författare)
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Bed agglomeration characteristics of biomass fuels using blast-furnace slag as bed material
- 2004
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Ingår i: Energy & Fuels. - Washington, D.C. : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 18:4, s. 1187-1193
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Tidskriftsartikel (refereegranskat)abstract
- Agglomeration of bed material may cause severe operating problems during fluidized bed combustion. The attack or coating layers that are formed on the bed particles during combustion play an important role in the agglomeration process. To reduce bed agglomeration tendencies, alternative bed materials may be used. In this paper, bed agglomeration characteristics during the combustion of biomass fuels using a relatively new bed material (iron blast-furnace slag) as well as ordinary quartz sand were determined. Controlled agglomeration tests lasting 40 h, using five representative biomass fuels (bark, olive residue, peat, straw, and reed canary grass) were conducted in a bench-scale fluidized bed. The bed materials and agglomerates were analyzed using SEM/EDS and X-ray diffraction. Chemical equilibrium calculations were performed to interpret the experimental findings. The results showed that blast-furnace slag had a lower tendency to agglomerate than quartz sand for most of the fuels. The quartz particles showed an inner attack layer more often than did the blast-furnace slag. The blast-furnace slag had a lower tendency to react with elements from the fuel. The outer coating layer had similar characteristics and thickness for both bed materials when the same fuel was combusted. However, the inner attack layer thickness was larger for quartz particles. SEM/EDS analyses of the agglomerates showed that the inner Ca-K-silicate-rich attack layer was responsible for the agglomeration of quartz sand. The composition of blast-furnace slag agglomerate was similar to the outer coating layer. Chemical equilibrium calculations showed that the original composition of the blast-furnace slag was close to the equilibrium composition, and hence there was no major driving force for reactions between that bed material and K and Ca from the fuel. The homogeneous silica-rich attack layer (with a low melting temperature) was not formed to the same extent for blast-furnace slag, thus explaining the lower bed agglomeration tendency.
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| 7. |
- Elliott, Kerryn, et al.
(författare)
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Elevated pyrimidine dimer formation at distinct genomic bases underlies promoter mutation hotspots in UV-exposed cancers.
- 2018
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Ingår i: PLoS genetics. - : Public Library of Science (PLoS). - 1553-7404. ; 14:12
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Tidskriftsartikel (refereegranskat)abstract
- Sequencing of whole cancer genomes has revealed an abundance of recurrent mutations in gene-regulatory promoter regions, in particular in melanoma where strong mutation hotspots are observed adjacent to ETS-family transcription factor (TF) binding sites. While sometimes interpreted as functional driver events, these mutations are commonly believed to be due to locally inhibited DNA repair. Here, we first show that low-dose UV light induces mutations preferably at a known ETS promoter hotspot in cultured cells even in the absence of global or transcription-coupled nucleotide excision repair (NER). Further, by genome-wide mapping of cyclobutane pyrimidine dimers (CPDs) shortly after UV exposure and thus before DNA repair, we find that ETS-related mutation hotspots exhibit strong increases in CPD formation efficacy in a manner consistent with tumor mutation data at the single-base level. Analysis of a large whole genome cohort illustrates the widespread contribution of this effect to recurrent mutations in melanoma. While inhibited NER underlies a general increase in somatic mutation burden in regulatory elements including ETS sites, our data supports that elevated DNA damage formation at specific genomic bases is at the core of the prominent promoter mutation hotspots seen in skin cancers, thus explaining a key phenomenon in whole-genome cancer analyses.
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| 8. |
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| 9. |
- Karlström, Anders, 1977, et al.
(författare)
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An extended analytical model including a layered
- 2005
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Ingår i: Environmental Vibrations, ISEV2005. - 0415390354 ; , s. 303-310
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Ground vibrations are investigated with an analytical approach. The ground is modelled as a layered half-space on which a layered embankment is placed. Situated on top of the embankment, the sleepers are modelled with an anisotropic Kirchhoff plate and the rails as Euler-Bernoulli beams. In the equation for the rails, propagating wheel loads with constant velocity are accounted for. The analyzing method is based on Fourier transforms in time and along the space coordinate parallel with the track. In the transverse direction Fourier transforms are adopted in the ground, whereas Fourier cosine and Fourier sine series are used in the embankment layers. The numerical scheme is very efficient. In particular the beam-like rectangular elastic region (embankment) is compared with the Euler-Bernoulli beam, both supported on a layered ground. With the same bending stiffness, the two solutions are seen to differ already from 0 Hz.
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| 10. |
- Karlström, Anders, 1977, et al.
(författare)
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Efficiency of trenches along railways for trains moving at sub- or supersonic speeds
- 2007
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Ingår i: Soil Dynamics and Earthquake Engineering. ; 27, s. 625-641
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Tidskriftsartikel (refereegranskat)abstract
- A full 3D analytical approach is adopted to account for trenches on one or both sides close to a railroad. Low-frequency ground vibrations are investigated due to passing trains, and open trenches are used as wave barriers. The modelling technique is based on Fourier transforms and Fourier series. The ground is modelled as a layered semi-infinite domain and the embankment with finite layers. The trenches are obtained by simulating the upper surface layer with two or three finite rectangular regions with appropriate widths. A particular boundary condition is adopted on the vertical sides of all finite regions to enable the solution procedure. Rails and sleepers are accounted for with Euler-Bernoulli beams and an anisotropic plate with transversal isotropy. The wheel loads from the boggie wheel pairs of the train are simulated as moving forces. Hence, no irregularities in rails or wheels are accounted for.
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| 11. |
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| 12. |
- Lindberg, Gustav, et al.
(författare)
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Determination of thermodynamic properties of Na2S using solid-state EMF measurements
- 2007
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Ingår i: Journal of Chemical Thermodynamics. - : Elsevier. - 0021-9614 .- 1096-3626. ; 39:1, s. 44-48
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Tidskriftsartikel (refereegranskat)abstract
- To obtain reliable thermodynamic data for Na2S(s), solid-state EMF measurements of the cell Pd(s)|O2(g)|Na2S(s), Na2SO4(s)|YSZ| Fe(s), FeO(s)|O2(g)ref| Pd(s) were carried out in the temperature range 870 < T/K < 1000 with yttria stabilized zirconia as the solid electrolyte. The measured EMF values were fitted according to the equation Efit/V (±0.00047) = 0.63650 − 0.00584732(T/K) + 0.00073190(T/K) ln (T/K). From the experimental results and the available literature data on Na2SO4(s), the equilibrium constant of formation for Na2S(s) was determined to be lg Kf(Na2S(s)) (±0.05) = 216.28 − 4750(T/K)−1 − 28.28878 ln (T/K). Gibbs energy of formation for Na2S(s) was obtained as ΔfG(Na2S(s))/(kJ · mol−1) (±1.0) = 90.9 − 4.1407(T/K) + 0.5415849(T/K) ln (T/K). By applying third law analysis of the experimental data, the standard enthalpy of formation of Na2S(s) was evaluated to be ΔfH(Na2S(s), 298.15 K)/(kJ · mol−1) (±1.0) = −369.0. Using the literature data for Cp and the calculated ΔfH, the standard entropy was evaluated to S(Na2S(s), 298.15 K)/(J · mol−1 · K−1) (±2.0) = 97.0.
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| 13. |
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| 14. |
- Schmidt, Peter, 1965-
(författare)
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Analysis of adhesively bonded joints : an asymptotic approach
- 2001
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Simulations using the Finite Element Method (FEM) play an increasingly important role in the design process of joints and fasteners in the aerospace industry. In order to utilize the potential of using adhesive bonding, there is an increasing need for effective and accurate computational methods. The geometry and the nature of an adhesive joint is, however, not so simple to describe effectively using regular FEM-codes. The main reason is that the very thin and soft adhesive layer must be modelled by a large number of FEM-elements in the thickness direction to achieve sufficiently accurate calculations. To overcome this difficulty, special FEM-elements can be developed that provides a material surface treatment of the adhesive and the joined parts. In order to create a model that reflects the above features one may introduce proper scalings on the geometry and on the material properties in terms of a perturbation parameter. Within the framework of three-dimensional elasticity, together with an asymptotic expansion method, a material surface model is obtained through a systematic procedure of derivation. In such derivation no a priori assumptions on the displacements or stress fields are needed. The final result is a variational equation posed over a single reference surface, which forms the basis of a structural element for the compound joint.
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| 15. |
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| 16. |
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| 17. |
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| 18. |
- Alinezhad, Saeid, et al.
(författare)
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Validation of novel biomarkers for prostate cancer progression by the combination of bioinformatics, clinical and functional studies
- 2016
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 11:5
-
Tidskriftsartikel (refereegranskat)abstract
- The identification and validation of biomarkers for clinical applications remains an important issue for improving diagnostics and therapy in many diseases, including prostate cancer. Gene expression profiles are routinely applied to identify diagnostic and predictive biomarkers or novel targets for cancer. However, only few predictive markers identified in silico have also been validated for clinical, functional or mechanistic relevance in disease progression. In this study, we have used a broad, bioinformatics-based approach to identify such biomarkers across a spectrum of progression stages, including normal and tumor-adjacent, premalignant, primary and late stage lesions. Bioinformatics data mining combined with clinical validation of biomarkers by sensitive, quantitative reverse-transcription PCR (qRT-PCR), followed by functional evaluation of candidate genes in disease-relevant processes, such as cancer cell proliferation, motility and invasion. From 300 initial candidates, eight genes were selected for validation by several layers of data mining and filtering. For clinical validation, differential mRNA expression of selected genes was measured by qRT-PCR in 197 clinical prostate tissue samples including normal prostate, compared against histologically benign and cancerous tissues. Based on the qRT-PCR results, significantly different mRNA expression was confirmed in normal prostate versus malignant PCa samples (for all eight genes), but also in cancer-adjacent tissues, even in the absence of detectable cancer cells, thus pointing to the possibility of pronounced field effects in prostate lesions. For the validation of the functional properties of these genes, and to demonstrate their putative relevance for disease-relevant processes, siRNA knock-down studies were performed in both 2D and 3D organotypic cell culture models. Silencing of three genes (DLX1, PLA2G7 and RHOU) in the prostate cancer cell lines PC3 and VCaP by siRNA resulted in marked growth arrest and cytotoxicity, particularly in 3D organotypic cell culture conditions. In addition, silencing of PLA2G7, RHOU, ACSM1, LAMB1 and CACNA1D also resulted in reduced tumor cell invasion in PC3 organoid cultures. For PLA2G7 and RHOU, the effects of siRNA silencing on proliferation and cell-motility could also be confirmed in 2D monolayer cultures. In conclusion, DLX1 and RHOU showed the strongest potential as useful clinical biomarkers for PCa diagnosis, further validated by their functional roles in PCa progression. These candidates may be useful for more reliable identification of relapses or therapy failures prior to the recurrence local or distant metastases.
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| 19. |
- Alopaeus, Tea, et al.
(författare)
-
Med de nya svenska klimatmålen i sikte : Gapanalys samt strategier och förutsättningar för att nå etappmålen 2030 med utblick mot 2045
- 2017
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Under våren 2017 presenterade Naturvårdsverket scenarier för hur växthusgasutsläppen i Sverige skulle kunna utvecklas till 2035. Sedan Naturvårdsverket presenterade scenarierna har ett nytt klimatpolitiskt ramverk för Sverige beslutats av riksdagen med nya klimatmål till 2030, 2040 och 2045. Regeringen har även presenterat ett antal nya styrmedel i budgetpropositionen.Naturvårdsverket ska inom miljömålssystemet löpande och strategiskt analysera och utvärdera styrmedel och åtgärder. Naturvårdsverket har mellan maj och november 2017 gjort en första uppföljning mot de nya klimatmålen. I denna rapport presenteras hur beslutade och planerade styrmedel kan komma att falla ut givet olika antagande. En översiktlig analys av styrmedel görs också.Arbetsgruppens sammansättning har varierat över tid. Sammantaget har följande personer på Naturvårdsverket deltagit i arbetsgruppen: Tea Alopaeus (projektledare), Björn Boström, Mats Björsell, Martin Boije, Joanna Dickinson, Dag Henning, Daniel Engström Stenson, Eva Jernbäcker (projektledare till september), Julien Morel, Miriam Münnich Vass, Karl-Anders Stigzelius, Ulrika Svensson, Per Wollin.Stockholm 29 november 2017Björn RisingerGeneraldirektör
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| 20. |
- Berbyuk, Viktor, 1953, et al.
(författare)
-
Energy-optimal control of bipedal locomtion systems
- 2002
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Ingår i: J. Stability and Control: Theory and Application, (SACTA).. - 1563-3276. ; 4:2, s. 74-89
-
Tidskriftsartikel (refereegranskat)abstract
- The mathematical statement of the problem of energy-optimal control for a bipedal locomotion system is given. The proposed statement of the problem is characterized by broad utilization of experimental data of normal human locomotion. It is done mainly by means of the mathematical formulation of the constraints imposed both on the phase coordinates and on the controlling stimuli of a system. A numerical method for the solution of optimal control problems for highly nonlinear and complex bipedal locomotion systems is proposed. The method is based on a special procedure of converting the initial optimal control problem into a standard nonlinear programming problem. This is made by an approximation of the independent variable functions using smoothing cubic splines and by the solution of inverse dynamics problem. The key features of the method are its high numerical effectiveness and the possibility to satisfy a lot of restrictions imposed on the phase coordinates of the system automatically and accurately. The proposed method is illustrated by computer simulation of the energy-optimal anthropomorphic motion of the bipedal walking robot over a horizontal surface.
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| 21. |
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| 22. |
- Berbyuk, Viktor, 1953, et al.
(författare)
-
Ice detection for smart de-icing of wind turbines
- 2017
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Icing on a wind turbine rotor blade is a problem in the operation of wind turbines in cold climates. Ice detection is a critical process to get a workable cost-effective wind turbine de-icing system. The paper presents the theoretical models, methods, algorithms, principles, and a demonstrator that are the basis for developing a new technique for detecting icing on rotor blades of a wind turbine based on acoustic wave propagation in composite structures. Two methods have been proposed: guided acoustic wave propagation and bulk acoustic wave propagation in composite structures. Analysis of computer simulations and the results of experimental study obtained by using the developed demonstrator in cold climate lab has shown that the integration of the guided acoustic wave propagation and the bulk acoustic wave propagation methods provides an efficient scientific approach to be used for the design of new ice detection system for wind turbines in cold climate regions. In particular, the guided acoustic wave propagation method makes it possible to detect ice and icing area location on the rotor blades. Several criteria (Icing Index, Frequency Factor Index, others) have been proposed for ice detection of composite structures. Bulk acoustic wave propagation method makes it possible to identify the time-varying spatially heterogeneous “landscapes” over the blade surface for each of the following eight ice parameters: thickness, the volumetric bulk density, bulk and shear moduli, stress relaxation time, porosity, and volume and shear viscosities. These data are necessary for smart, energy-efficient de-icing systems. The identification algorithm is computationally efficient and can be implemented in the real-time mode. A LIDAR (Light Detection And Ranging) for the detection of early ice growth on the wind turbine blades has also designed, tested and evaluated in this project. LIDAR uses laser pulses that emit at two different wavelengths and is capable of distinguishing between a thin layer of ice and water covering the turbine blades. The results of the tests that have been carried out in the project are undeniable. LIDAR detects early ice growth by measuring the difference in reflectivity of a surface by using two different laser wavelengths. The limitation of LIDAR is that it cannot be used to determine the amount of ice on the sheet, only if there is ice or not. The obtained results can be used to develop smart de-icing systems for wind turbines operating in cold climates, and can lead to new future products that are sought after by wind power industry. Since the efficient ice detection systems can increase wind turbine profitability, the results contribute to an increased ability to establish multiple wind turbines in cold regions.
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| 23. |
- Berbyuk, Viktor, 1953, et al.
(författare)
-
Modeling an design of robotic systems having spring-damper actuators
- 2000
-
Ingår i: Proceedings of the 7th Mechatronics Forum International Conference, 6-8 September 2000, Atlanta, Georgia, USA, PERGAMON, 2000.. - 0080437036
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The role of inherent dynamics for the improvement of control strategies of robotic systems is studied. A mathematical formulation of the optimal control problem that is suitable for this investigation is proposed. In solving this problem closed-form expressions have been obtained for the optimal control strategies for n degrees-of-freedom robotic systems with passive (unpowered) drives and no restrictions upon their controlling stimuli, and with non-linear viscoelastic spring-damper actuators. The obtained results can be used in designing optimal spring-damper-like passive drives for robotic systems.
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| 24. |
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| 25. |
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| 26. |
- Berbyuk, Viktor, 1953, et al.
(författare)
-
Optimization of control laws of the bipedal locomotion systems
- 1999
-
Ingår i: In Advances in Computational Multibody Dynamics, Jorge A.C. Ambrósio and Werner O. Schiehlen (Eds.), IDMEC/IST, Lisbon, Portugal, September 20-23, 1999. ; , s. 713-728
-
Konferensbidrag (refereegranskat)abstract
- The mathematical statement of the problem of energy-optimal control for a bipedal locomotion system is given. The proposed statement of the problem is characterized by broad utilization of experimental data of normal human locomotion. It is done mainly by means of the mathematical formulation of the constraints imposed both on the phase coordinates and on the controlling stimuli of a system. A numerical method for the solution of the optimal control problems for highly nonlinear and complex bipedal locomotion systems is proposed. The method is based on a special procedure of converting the initial optimal control problem into a standard nonlinear programming problem. This is made by an approximation of the independent variable functions using smoothing cubic splines and by the solution of an inverse dynamics problem. The key features of the method are its high numerical effectiveness and the possibility to satisfy a lot of restrictions imposed on the phase coordinates of the system automatically and accurately. The proposed method is illustrated by computer simulation of the energy-optimal anthropomorphic motion of the bipedal walking robot over a horizontal surface.
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| 27. |
- Berbyuk, Viktor, 1953, et al.
(författare)
-
Optimization problems of controlled multibody systems having spring-damper actuators
- 2001
-
Ingår i: International Applied Mechanics. ; 37:7, s. 935-940
-
Tidskriftsartikel (refereegranskat)abstract
- The optimal control of the motion of mechanical systems is studied. A characteristic feature of these systems is the presence of passive actuators (springs, dampers, etc.). Energy-optimal control laws and structural parameters of nonlinear springdamper actuators are determined analytically, which is necessary to impart arbitrary motion to a controllable mechanical system with n degrees of freedom. As an example, a numerical solution is presented for the problem of designing an energy-optimal spring actuator for a robot manipulator of closed kinematic structure.
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| 28. |
- Berbyuk, Viktor, 1953, et al.
(författare)
-
Optimization problems of controlled multibody systems having spring-damper actuators
- 2000
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- To incorporate spring-damper actuators into the structure of multibody systems and to design optimally their parameters can give several advantages. In this paper, we tackle optimal control problems for multibody systems having spring-damper actuators. We study a fundamental question about optimal interaction between controlling stimuli generated by external drives and proportional-differential forces described by linear and angular stiffness and damping parameters. A range of questions are also addressed about the role of inherent dynamics, and how much multibody system should be governed by external drives and how much by the system's inherent dynamics. We are in particular investigating semi-passively actuated manipulator robots and bipedal walking mechanisms having spring-damper actuators. Results obtained can help to design simpler control systems of manipulator robots and legged autonomous mechanisms having less weight and energy consumption.
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| 29. |
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| 30. |
- Berg, Frenk van den, et al.
(författare)
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Results of the European collaborative project "Product Uniformity Control" to improve the inline sensing of mechanical properties and microstructure of automotive steels
- 2018
-
Ingår i: e-Journal of Nondestructive Testing (eJNDT). - 1435-4934. ; 23:8
-
Tidskriftsartikel (refereegranskat)abstract
- A European consortium consisting of four major steel manufacturers and ten academic technology institutes has conducted a research and development project, called “Product Uniformity Control“ (PUC) in the period 2013 to 2017. This project aimed to develop and improve non-destructive (inline) measurement techniques to characterise the (uniformity of the) microstructure of steel strip products. In this project, a multitude of strip steel samples from various stages of production have been collected from the four participating steel manufacturers. The samples have been characterised in various ways, namely on their (1) non-destructive measurement parameters using different techniques suited for inline evaluation, (2) fundamental ultrasonic and electromagnetic properties (wave speed, ultrasonic attenuation, magnetisation loops, coercive field), (3) tensile properties (stress-strain curves) and (4) microstructure (by optical micrographs and EBSD images). The correlations between these different characterisations will be addressed. Besides the experimental characterisation, a strong accent has been on modelling activities: during the project, fundamental models have been developed to describe, starting from 2D and 3D microstructures, the ultrasonic and magnetic properties, which are next used as input to sensor models that predict the output of the inline measurement systems. This contribution presents the recent results of experimental work, which underlines the importance of associated modelling studies for the interpretation of the measurement data for the benefit of inline characterisation of the mechanical properties complementary to traditional destructive tensile testing.
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| 31. |
- Bjursell, Cecilia, 1970-, et al.
(författare)
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Intergenerational learning in a changing world : Knitting generations together
- 2023
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Ingår i: Ricerche di Pedagogia e Didattica. - : University of Bologna. - 1970-2221. ; 18:2, s. 51-65
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Tidskriftsartikel (refereegranskat)abstract
- In intergenerational projects, learning a craft is an activity that may be of interest to people of different ages. This paper focuses on knitting as a craft. In most Western societies, knitting is often considered a craft for women, but on Taquile Island, Peru, it is the men who knit. This paper discusses knitting from an intergenerational perspective whilst focusing on gender and culture. To this aim, we introduce an intrinsic case study to examine the role of gender and culture in intergenerational learning. The data used in this study was collected during a visit to Taquile Island. In summary, the study’s findings reveal that (i) on Taquile, members of the community invest in maintaining cultural traditions in opposition to being swept along by (con)temporary social changes; (ii) knitting on Taquile is approached as a practical technique in contrast to Western culture where knitting is connected to the concept of ‘well-being’; and (iii) whilst gender structures may set frames for performance, the Taquile case demonstrates that what is typically considered ‘male’ or ‘female’ may vary.
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| 32. |
- Björnfot Holmström, Sofia, et al.
(författare)
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MMP-12 and S100s in saliva reflect different aspects of periodontal inflammation
- 2019
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Ingår i: Cytokine. - : Academic Press. - 1043-4666 .- 1096-0023. ; 113, s. 155-161
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Tidskriftsartikel (refereegranskat)abstract
- Matrix metalloproteinase (MMP)-12, S100A8/A9, and S100A12 are involved in innate immune responses. We addressed whether different aspects of oral health and non-disease-related covariates influence their levels in saliva. 436 participants were clinically examined, completed a health questionnaire, and provided stimulated saliva. Salivary levels of MMP-12, S100A8/A9, and S100A12 were determined by enzyme-linked immunosorbent assays. Lower MMP-12 levels were observed in individuals 40-64years old (yo) compared to < 40yo, and higher S100A8/A9 levels were found in individuals > 64yo compared to 40-64yo. Smokers exhibited lower MMP-12 and S100A12 levels compared to non-smokers. All three proteins were elevated in individuals with bleeding on probing (BOP)>20% compared to those with BOP/= 10% gingival pocket depths (PPD)>/=4mm compared to the ones with shallow pockets < 4mm. The extent of alveolar bone loss or presence of manifest caries did not alter any of the markers. MMP-12, S100A8/A9, and S100A12 levels were higher in participants with high periodontal inflammatory burden. All three proteins correlated positively to BOP, PPD, and to several inflammatory mediators. The explanatory variables for MMP-12 in saliva were age, smoking, presence of any tumor, and percentage of PPD>/=4mm. The determinant of salivary S100A8/A9 was percentage of BOP, while S100A12 levels were associated with percentage of BOP and presence of any tumor. Taken together, MMP-12 and the S100/calgranulin levels in saliva reflect different aspects of periodontal inflammation. Smoking and age should be taken into account in further investigation of these proteins as biomarker candidates of periodontal disease.
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| 33. |
- Boman, Christoffer, et al.
(författare)
-
Characterization of inorganic particulate matter from residential combustion of pelletized biomass fuels
- 2004
-
Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 18:2, s. 338-348
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Tidskriftsartikel (refereegranskat)abstract
- The increased focus on potential adverse health effects associated with exposure to ambient particulate matter (PM) motivates a careful characterization of particle emissions from different sources. Combustion is a major anthropogenic source of fine PM, and, in urban areas, traditional residential wood combustion can be a major contributor. New and upgraded biomass fuels have become more common, and fuel pellets are especially well-suited for the residential market. The objective of the present work was to determine the mass size distributions, elemental distributions, and inorganic-phase distributions of PM from different residential combustion appliances and pelletized biomass fuels. In addition, chemical equilibrium model calculations of the combustion process were used to interpret the experimental findings. Six different typical pellet fuels were combusted in three different commercial pellet burners (10-15 kW). The experiments were performed in a newly designed experimental setup that enables constant-volume sampling. Total-PM mass concentrations were measured using conventional filters, and the fractions of products of incomplete combustion and inorganic material were thermally determined. Particle mass size distributions were determined using a 13-step low-pressure cascade impactor with a precyclone. The PM was analyzed for morphology (using environmental scanning electron microscopy, ESEM), elemental composition (using energy-dispersive spectroscopy, EDS), and crystalline phases (using X-ray diffractometry, XRD). For complementary chemical structural characterization, time-of-flight secondary ion mass spectrometry (TOF-SIMS), X-ray photoelectron spectroscopy XPS and X-ray absorption fine structure (XAFS) spectroscopy were also used. The emitted particles were mainly found in the fine ( less than or equal 1 μm) mode with mass median aerodynamic diameters of 0.20 - 0.39 μm and an average PM1 of 89.5% ± 7.4% of total PM. Minor coarse-mode fractions (>1 μm) were present primarily in the experiments with bark and logging residues. Relatively large and varying amounts (28%-92%) were determined to be products of incomplete combustion. The inorganic elemental compositions of the fine particles were dominated by potassium, chlorine, and sulfur, with minor amounts of sodium and zinc. The dominating alkali phase was KCl, with minor but varying amounts of K3Na(SO4)2 and, in some cases, also K2SO4. The results showed that zinc is almost fully volatilized, subsequently and presumably forming a more complex solid phase than that previously suggested (ZnO). However, the formation mechanism and exact phase identification remain to be elucidated. With some constrains, the results also showed that the amounts and speciation of the inorganic PM seemed to be quite similar to that predicted by chemical equilibrium calculations.
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| 34. |
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| 35. |
- Boman, Christoffer, et al.
(författare)
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Stove performance and emission characteristics in residential wood log and pellet combustion : Part 1: Pellet stoves
- 2011
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 25:1, s. 307-314
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Tidskriftsartikel (refereegranskat)abstract
- Stove performance, characteristics and quantities of gaseous and particulate emissions were determined for two different pellet stoves, varying fuel load, pellet diameter and chimney draught. This approach aimed at covering variations in emissions from stoves in use today. The extensive measurement campaign included CO, NOx, organic gaseous carbon, volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs), total particulate matter (PMtot) as well as particle mass and number concentrations, size distributions and inorganic composition. At high load, most emissions were similar. For stove B, operating at high residual oxygen and solely with primary air, the emissions of PMtot and particle numbers were higher while the particles were smaller. Lowering the fuel load, the emissions of CO and hydrocarbons increased dramatically for stove A, which operated continuously also at lower fuel loads. On the other hand for stove B, which had intermittent operation at lower fuel loads, the emissions of hydrocarbons increased only slightly lowering the fuel load, while CO emissions increased sharply, due to high emissions at the end of the combustion cycle. Beside methane, dominating VOCs were ethene, acetylene and benzene and the emissions of VOC varied in the range 1.1-47 mg/MJfuel. PAH emissions (2-340 µg/MJfuel) were generally dominated by phenantrene, fluoranthene and pyrene. PMtot (15-45 mg/MJfuel) were in all cases dominated by fine particles with mass median diameters in the range 100-200 nm, peak mobility diameters of 50-85 nm and number concentrations in the range 4×1013- 3×1014 particles/MJfuel. During high load conditions the particulate matter was totally dominated by inorganic particles at 15-25 mg/MJfuel consisting of potassium, sodium, sulfur and chlorine, in the form of K2SO4, K3Na(SO4)2 and KCl. The study shows that differences in operation and modulation principles for the tested pellet stoves, relevant for appliances in use today, will affect the performance and emissions significantly, although with lower scattering in the present study compared to compiled literature data.
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| 36. |
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| 37. |
- Boran, Colm, et al.
(författare)
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Saving Lives with V2X versus On-Board Sensing Systems -Which will be More Effective?
- 2012
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Ingår i: SAE Technical Papers. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191 .- 2688-3627.
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Tidskriftsartikel (refereegranskat)abstract
- Infrastructure systems such as vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2X) communication can theoretically prevent nearly all accidents by gathering the speed, locations, and travel directions of traffic participants, and intervening to control vehicle motion as required to help prevent collisions. However, during the phase-in of the communication systems, there will be many vehicles and many roads that do not have the communication systems in place, and therefore the system will not be effective in those cases. This lack of availability is likely the main disadvantage.On-board sensing (autonomous) systems such as cameras and radar sensors may not detect all potential hazards (e.g. due to weather, or hidden hazards), but they are effective in many situations and can help prevent crashes without depending on communication with infrastructure or other vehicles.This paper evaluates and compares the effectiveness of communication and on-board sensing technology in saving lives. Various implementation scenarios and system capabilities are investigated.
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| 38. |
- Boström, Annika, et al.
(författare)
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Duplex scanning as the sole preoperative imaging method for infrainguinal arterial surgery
- 2002
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Ingår i: European Journal of Vascular and Endovascular Surgery. - : Elsevier BV. - 1078-5884 .- 1532-2165. ; 23:2, s. 140-145
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: to evaluate preoperative duplex as the sole investigation prior to lower limb reconstruction. Design retrospective analysis. MATERIALS AND METHODS: between January 1995 and December 1999, 157 of 329 surgical interventions for chronic infrainguinal arterial or aneurysmal disease were performed without preoperative angiography. RESULTS: in patients undergoing femoral artery endarterectomy, the extent of the stenosis and the status of the distal deep femoral artery were correctly diagnosed with duplex scanning in all but one patient. Duplex scan findings in patients undergoing infrainguinal bypass procedures were in agreement with the findings obtained from on-table angiography in regard to the selection of optimal outflow anastomotic sites in 123 (98%). Duplex scanning correctly evaluated the status of runoff in 113 (90%). There were no significant differences in 30-day occlusion rate and patency at 12 months between reconstructions performed with and without preoperative angiography. CONCLUSION: in patients with conclusive duplex scan findings there is no need to perform angiography prior to lower limb reconstruction.
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| 39. |
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| 40. |
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| 41. |
- Boström, Anders E, 1951
(författare)
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Acoustic scattering by a sound-hard rectangle
- 1991
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Ingår i: Journal of the Acoustical Society of America. - 1520-8524 .- 0001-4966. ; 90, s. 3344-3347
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Tidskriftsartikel (refereegranskat)abstract
- The scattering of an incoming plane wave by a sound-hard infinitely thin rectangle is considered. Starting from a double spatial Fourier transform representation of the scattered wave, a matching of the conditions in the plane of the rectangle leads to an integral equation for the potential jump across the rectangle. The jump is expanded in a double series in Chebyshev polynomials which fulfill the right edge conditions (but no special measures are taken for the corners where the right conditions are anyway unknown). The integral equation is thus discretized and the only tricky part is the computations of double integrals in the systen matrix where special care must be excercised. A double stationary phase analysis gives the scattered far fields, and some numerical examples of total scattering cross sections are given.
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| 42. |
- Boström, Anders E, 1951
(författare)
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Acoustic waves in a cylindrical duct with periodically varying cross section
- 1983
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Ingår i: Wave Motion. - 0165-2125. ; 5, s. 59-67
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Tidskriftsartikel (refereegranskat)abstract
- The null field approach is used to study the propagation of acoustic waves in a rotationally hard-walled duct with periodically varying cross section. For a radius that varies sinusoidally along the axial distance, numerical computations give the axial wave number and the passbands and stopbands of the modes of the duct. In particular, small passbands are seen to exist even for very large variations in radius, and probably all the way to the point where the duct is cut off. We also present some plots which show the pressure pattern inside the duct.
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| 43. |
- Boström, Anders E, 1951, et al.
(författare)
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Acoustics of an obstacle inside a reactive silencer
- 1983
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Ingår i: Journal of Sound and Vibration. - 1095-8568 .- 0022-460X. ; 87, s. 603-619
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Tidskriftsartikel (refereegranskat)abstract
- The transmission and reflection coefficients of sound in a cylindrical duct containing several discontinuities are investigated. A building-block method, which gives the transmission and reflection coefficients for a complex system from those of the parts, is applied to bifurcations, sudden area changes with or without extended inlets, and spherical obstacles (which may be lossy). In some cases the solution can be interpreted in terns of multiple reflections. When the length between the discontinuities are small it is important to include also non-propagating modes, and this is especially true when the sudden area change is obtained from the area change with extended inlet in the limit of vanishing inlet. For an expansion chamber (a portion of the duct with a larger radius) with or without an obstacle and with or without inlets a number of numerical results with variation in frequency are presented. Numerical results for the various building-block elements of the expansion chamber are also considered.
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| 44. |
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| 45. |
- Boström, Anders E, 1951, et al.
(författare)
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Dynamic equations for an orthotropic plate
- 2010
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Ingår i: Proceedings of the International Conference Days on Diffraction, DD 2010. St. Petersburg, 8-11 June 2010. - 9785965105298 ; , s. 35-39
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Konferensbidrag (refereegranskat)abstract
- A hierarchy of dynamic plate equations is derived for an orthotropic elastic plate. Using power series expansions in the thickness coordinate for the displacement components, recursion relations are obtained among the expansion functions. Using these in the boundary conditions on the plate surfaces, a set of dynamic equations are derived. These can be truncated to any order and are believed to be asymptotically correct. A comparison for the dispersion curves is made with exact 3D theory and other approximate theories.
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| 46. |
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| 47. |
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| 48. |
- Boström, Anders E, 1951, et al.
(författare)
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Elastic SH wave propagation in a layered anisotropic plate with interface damage modelled by spring boundary conditions
- 2009
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Ingår i: Quarterly Journal of Mechanics and Applied Mathematics. - : Oxford University Press (OUP). - 0033-5614 .- 1464-3855. ; 62:1, s. 39-52
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Tidskriftsartikel (refereegranskat)abstract
- Elastic SH wave propagation in a layered anisotropic plate withinterface damage is modelled in several steps. A single interfacecrack between two half-spaces is first studied and an explicitsolution for the crack-opening displacement is obtained at lowfrequencies. This is then generalized to a random distribution ofcracks at the interface and the result is reformulated as a springboundary condition. As an example of its usefulness,this boundary condition is then used in thederivation of a plate equation by expanding the displacements inpower series in the thickness coordinate.
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| 49. |
- Boström, Anders E, 1951, et al.
(författare)
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Elastic SH wave propagation in a layered anisotropic plate with periodic interface cracks: exact versus spring boundary conditions
- 2010
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Ingår i: Journal of Mechanics of Materials and Structures. - : Mathematical Sciences Publishers. - 1559-3959. ; 5:1, s. 67-78
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Tidskriftsartikel (refereegranskat)abstract
- The propagating antiplane (SH) modes in a symmetrically three-layered, anisotropic, thick plate with a periodic array of interface cracks are investigated. The exact dispersion relation can be derived with the help of a hypersingular integral equation approach and Floquet's theorem. The interface cracks can be a model for interface damage, but a much simpler model is a recently developed spring boundary condition. This boundary condition is used both for the thick plate and in the derivation of plate equations with the help of power series expansions in the thickness coordinate. For low frequencies (cracks small compared to the wavelength) the three models are shown to give the same results and this is a confirmation that the spring boundary condition is a valid approximation at low frequencies.
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| 50. |
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