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  • 201.
    Balieu, Romain
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Bro- och stålbyggnad.
    Modèle viscoélastique-viscoplastique couplé avec endommagement pour les matériaux polymères semi-cristallins2012Manuskript (preprint) (Annet vitenskapelig)
  • 202.
    Balieu, Romain
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Väg- och banteknik.
    Lauro, F.
    Bennani, B.
    Haugou, G.
    Chaari, F.
    Matsumoto, T.
    Mottola, E.
    Damage at high strain rates in semi-crystalline polymers2015Inngår i: International Journal of Impact Engineering, ISSN 0734-743X, E-ISSN 1879-3509, Vol. 76, s. 1-8Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A specific damage characterization method using Digital Image Correlation for semi-crystalline polymers is proposed for a wide range of strain rates. This damage measurement is an extension of the SEE method [16] which was developed to characterize the behaviour laws at constant strain rates of polymeric materials. This procedure is compared to the well-known damage characterization by loss of stiffness technique under quasi-static loading. In addition, an in-situ tensile test, carried out in a microtomograph, is used to observe the cavitation phenomenon in real time. The different ways used to evaluate the damage evolution are compared and the proposed technique is also suitable for measuring the ductile damage observed in semi-crystalline polymers under dynamic loading.

  • 203.
    Banaem, Hossein Y
    et al.
    Tehran University of Medical Science.
    Ahmadian, Alireza
    Tehran University of Medical Science.
    Saberi, Hooshangh
    Tehran University of Medical Science.
    Daneshmehr, Alireza
    University of Tehran.
    Khodadad, Davood
    Tehran University of Medical Science.
    Brain tumor modeling: glioma growth and interaction with chemotherapy2011Inngår i: Proceedings of SPIE, the International Society for Optical Engineering, ISSN 0277-786X, E-ISSN 1996-756X, Vol. 8285Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In last decade increasingly mathematical models of tumor growths have been studied, particularly on solid tumors which growth mainly caused by cellular proliferation. In this paper we propose a modified model to simulate the growth of gliomas in different stages. Glioma growth is modeled by a reaction-advection-diffusion. We begin with a model of untreated gliomas and continue with models of polyclonal glioma following chemotherapy. From relatively simple assumptions involving homogeneous brain tissue bounded by a few gross anatomical landmarks (ventricles and skull) the models have been expanded to include heterogeneous brain tissue with different motilities of glioma cells in grey and white matter. Tumor growth is characterized by a dangerous change in the control mechanisms, which normally maintain a balance between the rate of proliferation and the rate of apoptosis (controlled cell death). Result shows that this model closes to clinical finding and can simulate brain tumor behavior properly.

  • 204.
    Banaem, Hossein Yousefi
    et al.
    Department of Biomedical Engineering, Faculty of Advance Medical Technology, Isfahan University of Medical Science.
    Kermani, Saeed
    Department of Biomedical Engineering, Faculty of Advance Medical Technology, Isfahan University of Medical Science.
    Sarrafzadeh, Omid
    Department of Biomedical Engineering, Faculty of Advance Medical Technology, Isfahan University of Medical Science.
    Khodadad, Davood
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    An improved spatial FCM algorithm for cardiac image segmentation2013Inngår i: 13th Iranian Conference on Fuzzy Systems: IFSC 2013, Qazvin, Iran; 27-29 August 2013, Piscataway, NJ: IEEE Communications Society, 2013, artikkel-id 6675656Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Image segmentation is one of challenging field in medical image processing. Segmentation of cardiac wall is one of challenging work and it is very important step in evaluation of heart functionality by existing methods. For cardiac image analysis, Fuzzy C- Means (FCM) algorithm proved to be superior over the other clustering approaches in segmentation field. However, the nave FCM algorithm is sensitive to noise because of not considering the spatial information in the image. In this paper an improved FCM algorithm is formulated by incorporating the spatial domain neighborhood information into the membership function for clustering (ISFCM). In this paper we applied improved Fuzzy c-Means with spatial information for left ventricular wall segmentation. Obtained results showed that the proposed method can segment cardiac wall automatically with acceptable accuracy. The comparison of proposed method with nave FCM proved that ISFCM can segment with more accuracy than nave FCM.

  • 205.
    Bandari, Shiva Ram
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Investigation on Flow Control Valve by CFD Simulation2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    In a water distribution system, Flow Control Valve is used to control the flow rate in the pipeline connections. In this thesis, a fixed flow control valve is investigated to reduce the flow rate and set to deliver the pre-set flow of 5-6 LPM (litre per minute). Which helps to distribute the water for a maximum period and maintains the usage only for the drinking purpose. A geometry of FCV with a ball check valve is implemented, where the ball check helps to stop the back flow of the fluid from the valve. Detailed inspection of dynamic changes in pressure and flow velocity in the valve are conducted through simulation. The study of fluid properties describes the expected design and specifies the flow structure in the valve. The results of this project demonstrate a good performance of the design-build and influence the requirements. The obtained values in the simulation, analytical and experimental results are compatible, which concludes the survey of FCV is equipped to custom.

  • 206.
    Baravdish, George
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Borachok, Ihor
    Ivan Franko Natl Univ Lviv, Ukraine.
    Chapko, Roman
    Ivan Franko Natl Univ Lviv, Ukraine.
    Johansson, B. Tomas
    Aston Univ, England.
    Slodicka, Marian
    Univ Ghent, Belgium.
    An iterative method for the Cauchy problem for second-order elliptic equations2018Inngår i: International Journal of Mechanical Sciences, ISSN 0020-7403, E-ISSN 1879-2162, Vol. 142, s. 216-223Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The problem of reconstructing the solution to a second-order elliptic equation in a doubly-connected domain from knowledge of the solution and its normal derivative on the outer part of the boundary of the solution domain, that is from Cauchy data, is considered. An iterative method is given to generate a stable numerical approximation to this inverse ill-posed problem. The procedure is physically feasible in that boundary data is updated with data of the same type in the iterations, meaning that Dirichlet values is updated with Dirichlet values from the previous step and Neumann values by Neumann data. Proof of convergence and stability are given by showing that the proposed method is an extension of the Landweber method for an operator equation reformulation of the Cauchy problem. Connection with the alternating method is discussed. Numerical examples are included confirming the feasibility of the suggested approach.

    Fulltekst tilgjengelig fra 2020-04-24 00:01
  • 207.
    Barba, D.
    et al.
    Univ Oxford, England.
    Alabort, E.
    Univ Oxford, England.
    Garcia-Gonzalez, D.
    Univ Oxford, England.
    Moverare, Johan
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Reed, R. C.
    Univ Oxford, England.
    Jerusalem, A.
    Univ Oxford, England.
    A thermodynamically consistent constitutive model for diffusion-assisted plasticity in Ni-based superalloys2018Inngår i: International journal of plasticity, ISSN 0749-6419, E-ISSN 1879-2154, Vol. 105, s. 74-98Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An elasto-viscoplastic thermodynamically consistent constitutive model for diffusion-assisted phase transformations is presented here. The model accounts for the different deformation mechanisms, their time dependence, the crystal rotations produced by microtwin propagation and the chemistry-plasticity coupling occurring at high temperature. It is applied to the study of the chemically assisted microtwinning observed in Ni-based superalloys in the temperature range of 600-800 degrees C. The model parameters are calibrated against multi-directional mechanical data from tensile creep tests of single crystal superalloy MD2. The constitutive model is then implemented into a crystal plasticity finite element code to study the activation of the different deformation mechanisms within single crystal and polycrystalline aggregates. Doing so, a relation between the rotations of the crystal and the creep life of the different crystal orientations is established. The results eventually reveal the critical role of the strong anisotropy of microtwin formation on the asymmetric behavior of the alloy and its relevant role on the mechanical performance.

  • 208.
    Barbagallo, Mathias
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
    Finnveden, Svante
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strukturakustik.
    A natural variational principle for Biot's equation: Waveguide FE and SEA of multilayered structures comprising porous materials2011Konferansepaper (Annet vitenskapelig)
  • 209.
    Barbagallo, Mathias
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
    Finnveden, Svante
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strukturakustik.
    A self-adjoint variational principle for anisotropic viscoelastic Biot’s equations2013Inngår i: International Journal of Engineering Science, ISSN 0020-7225, E-ISSN 1879-2197, Vol. 63, s. 71-83Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A variational principle for anisotropic viscoelastic Biot’s equations of motion is presented. It is based upon an extended Hamilton’s principle, also valid for dissipative systems. Using this principle, a functional analogous to the Lagrangian is defined, starting from Biot’s variational formulation based on frame and fluid displacements. Then, a mixed displacement–pressure formulation is presented, which reduces the number of variables of response from six to four. The corresponding functional analogous to the Lagrangian is derived making full use of variational calculus. The derived functionals are self-adjoint and stationary for true motion.

  • 210.
    Barbagallo, Mathias
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
    Finnveden, Svante
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strukturakustik.
    Characterisation of a generic trim-panel: sound reduction index and material parameters2013Rapport (Annet vitenskapelig)
  • 211.
    Barbagallo, Mathias
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
    Finnveden, Svante
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strukturakustik.
    Spatial energy decay and indirect couplings in statistical energy analysis2010Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Spatial energy decay within elements affects the validity of SEA. This is particularly significant for chains of similar long well-connected structures such as ventilation ducts, fluid-filled pipes and rib-stiffened plates found in ships, aircraft and railway cars. The effects of spatial energy decay on the high frequency response of one-dimensional well-connected elements are herein studied by comparing calculations by an SEA, a spectral finite element method and an SEA-like model. An SEA only includes direct coupling loss factors (CLFs); conversely, an SEA-like model also contains indirect CLFs. At high frequencies, the spatial energy decay increases and SEA overestimates the energies in all elements away from the excitation. Moreover, the indirect CLFs in the SEA-like model have to be considered when evaluating the energy flows, as the accumulated spatial decay from the excitation to the observed point increases. Thus, SEA cannot predict the high frequency response of similar long well-connected elements and alternative formulations are needed.

  • 212.
    Barbagallo, Mathias
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
    Finnveden, Svante
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strukturakustik.
    Liu, Hao
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
    Statistical energy analysis of the sound transmission through layered panels using a variational formulation of the porous materialArtikkel i tidsskrift (Annet vitenskapelig)
  • 213.
    Barrskog, Jonas
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.), Hållfasthetslära (Avd.).
    Implementation of methods for computation of Tooth Interior Fatigue Fracture2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    For a company like Scania CV AB, a vast number of laws and regulations has to be considered when developing a truck. In the constant struggle to keep the generated noise below the allowed levels, the gears are made more slender and flexible. The slenderness in combination with case hardening has brought a new type of gear fracture into the light.The Tooth Interior Fatigue Fracture, TIFF. A 2D-method, and a tool for engineers, was developed in the early 2000’s. However, this tool did not provide sufficient accuracy andcompatibility with the current design process to be adopted by the engineers at Scania.This thesis expands on the current 2D-model and attempts to improve the accuracy by bringing the analysis to 3D. Furthermore, the computational tool is developed in Pythonto allow for a more streamlined interface with the current workflow.The proposed method approximates the tooth as a cantilever-beam, and is only evaluated for this case. However, the stresses are computed with good accuracy. The onlydiscrepancy is one of the stress components, where the error is about 50%. This error isderived from the decision to, in torsion, model the cross-section of the gear tooth as an ellipse. The method has potential to be incorporated into the current design process, but the accuracy of the stresses due to torsion has to be improved, and some of the equations has to be adapted before real gear geometries can be considered.

  • 214. Barsoum, I.
    et al.
    Faleskog, Jonas
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.).
    Pingle, S.
    The effect of stress state on ductility in the moderate stress triaxiality regime of medium and high strength steels2012Inngår i: International Journal of Mechanical Sciences, ISSN 0020-7403, E-ISSN 1879-2162, Vol. 65, nr 1, s. 203-212Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Experiments on double notched tube specimens subjected to tension and torsion were conducted by Barsoum and Faleskog (2007) [8,9]. In this study a complementary experimental investigation was conducted on tensile round circumferentially notched bar specimens. The results from the current study were compared with the results from the double circumferentially notched tube specimens with stress triaxiality larger than 0.7 in order to asses the influence of the Lode parameter on ductility in the moderate stress triaxiality regime. The effective plastic strain, the stress triaxiality T and the Lode parameter L were determined at the center of the notch up to the point of onset of failure by means of finite element. The influence of the Lode parameter on the failure strain was significant for the high strength and low hardening material, whereas for the medium strength and high hardening material the influence of the Lode parameter was less distinguished. The experimental results were then analyzed with the micromechanical model proposed by Barsoum and Faleskog (2011) [15], which is based on the assumption that ductile failure is a consequence of that plastic deformation localizes into a band. The band consists of a square array of equally sized cells, with a spherical void located in the center of each cell, which allows for studying a single 3D unit cell with fully periodic boundary conditions. The unit cell is subjected to a proportional loading such that it resembles the stress state, in terms of T and L, from the experiments. The micromechanical model captures the experimental trend and the influence of L on ductility very well. It is found that the Lode parameter sensitivity increases by the combination of increase in the yield strength and decrease in strain hardening. The fractographical analysis reveals that this Lode parameter sensitivity is associated with the failure characteristics of the material.

  • 215.
    Barsoum, Zuheir
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Avancerade metoder för noggrannare dimensionering av svetsade konstruktioner2009Inngår i: Svetsen, ISSN 0039-7091, Vol. 68, nr 3Artikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
  • 216.
    Barsoum, Zuheir
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Fatigue Assessment of Cruciform Joints Welded with Different Methods2005Inngår i: IIW Doc. No. XIII-2074-05, 2005Konferansepaper (Annet vitenskapelig)
  • 217.
    Barsoum, Zuheir
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Fatigue design of welded structures: effect of weld quality and residual stresses, XIII-2312-102010Konferansepaper (Annet vitenskapelig)
  • 218.
    Barsoum, Zuheir
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Fatigue Strength of cruciform joints fabricated with different welding processes2007Inngår i: International Symposium on Integrated Design and Manufacturing of Welded Structures, Eskilstuna, 2007Konferansepaper (Annet vitenskapelig)
  • 219.
    Barsoum, Zuheir
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Local weld geometry and the influence on fatigue strength2010Inngår i: Proceedings of the Swedish Conference on Lightweight Optimised Welded Structures: Borlänge, March 24-25, 2009 / [ed] Zubeir Barsoum, Jack Samuelsson, Borlänge, 2010, s. 26-38Konferansepaper (Annet vitenskapelig)
  • 220.
    Barsoum, Zuheir
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Ny doktorsavhandling: Restspännings- och utmattningsanalyser av svetsade stålkonstruktioner2008Inngår i: Svetsen, ISSN 0039-7091, Vol. 67, nr 3Artikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
  • 221.
    Barsoum, Zuheir
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Prediction of Welding Residual Stresses2007Inngår i: International Symposium on Integrated Design and Manufacturing of Welded Structures, Eskilstuna, 2007Konferansepaper (Annet vitenskapelig)
  • 222.
    Barsoum, Zuheir
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Prediction of welding residual stresses by simplified approaches2010Inngår i: Proceedings of the Swedish Conference onLightweight Optimised Welded Structures: Borlänge, March 24-25, 2009 / [ed] Zubeir Barsoum, Jack Samuelsson, Stockholm: KTH Royal Institute of Technology, 2010, s. 39-50Konferansepaper (Annet vitenskapelig)
  • 223.
    Barsoum, Zuheir
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Residual stress predictin and relaxation in welded tubular joints under constant cyclic loading2006Inngår i: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 524-525, s. 323-330Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper three-dimensional welding simulations were carried out in FE software ANSYS in order to predict transient temperatures and the residual stresses in a three pass welded tubular joints. The thermal analysis and the moving heat source were verified with temperature measurements and the computed residual stresses were verified with hole drilling measurements. Then residual stress relaxation analyses were carried out on the tubular structure, with similar load cases as in earlier fatigue testing on the same tubular joint structures.

  • 224.
    Barsoum, Zuheir
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Barsoum, Imad
    Residual stress effects on fatigue life of welded structures using LEFM2008Konferansepaper (Fagfellevurdert)
  • 225.
    Barsoum, Zuheir
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Barsoum, Imad
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.).
    Residual stress effects on fatigue life of welded structures using LEFM2009Inngår i: IIW International Institute of Welding: 62nd AnnualAssembly, 2009Konferansepaper (Annet vitenskapelig)
  • 226.
    Barsoum, Zuheir
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg. Khalifa University.
    Bhatti, Ayjwat
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
    Balawi, S.
    Computational Weld Mechanics - Towards a Simplified and Cost Effective Approach for Large Welded Structures2015Inngår i: Procedia Engineering, 2015, s. 62-69Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The current paper presents the development of a finite element analysis framework for computational weld mechanics, in order to carry out cost-effective predictions of welding induced residual stresses with good accuracy. Different approaches for describing the welding heat sources were investigated. The paper also investigates the influence of thermo-mechanical material properties of frequently used steel grades (S355-S960) on welding residual stresses and angular distortion. The predicted residual stresses were validated experimentally on several different small scale specimens with X-ray diffraction techniques. Finally, the developed simulation framework is demonstrated on complex welded structures in a construction equipment vehicle.

  • 227.
    Barsoum, Zuheir
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg. Khalifa University.
    Ghanadi, M.
    Balawi, S.
    Managing Welding Induced Distortion - Comparison of Different Computational Approaches2015Inngår i: Procedia Engineering, Elsevier, 2015, s. 70-77Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This study aims to assess and compare three different approaches of inherent strain method for prediction of welding induced distortion; inherent strain, inherent deformation and shrinkage force approaches. The FEA was performed on T-fillet welded structures. The results are compared with elastic-plastic FEA and experiments and shows a qualitative good agreement. It is found that the inherent strain and inherent deformation approaches are suitable to predict transverse shrinkage and transverse bending whereas to predict the longitudinal shrinkage and longitudinal bending the shrinkage force approach is more suitable.

  • 228.
    Barsoum, Zuheir
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Gustafson, Mats
    Spectrum fatigue of high strength steel joints welded with low temperature transformation consumables2007Inngår i: 2nd International Conference on Fatigue Design, 2007Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In the present paper constant (CA) and variable amplitude (VA) fatigue testing have been carried out on out-ofplane gusset fillet welded high strength steel joints. The joints were welded with conventional weld fillermaterial and martensitic low transformation temperature weld filler, LTT, in order to study the influence of theresidual stress on the fatigue strength. Residual stress measurements were carried out close to the weld toe usingX-ray diffraction technique in order to study the relaxation due to VA fatigue. The residual stress showeddifferent level of relaxation depending on the VA spectrum loading used. The LTT joints shows ~40% increasein mean fatigue strength compared to the conventional joints in CA. The LTT joints shows ~12% increase inmean fatigue strength compared to the conventional joints. The LTT joints shows 33% increase in mean fatiguestrength in CA compared to VA testing. However, the improvement of the fatigue strength is less significant invariable amplitude testing mainly due to the relaxation of the compressive residual stresses.

  • 229.
    Barsoum, Zuheir
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Jonsson, Bertil
    Fatigue Assessment and LEFM Analysis of Cruciform Joints Fabricated with Different Welding Processes, XIII-2175-072007Inngår i: IIW International Institute of Welding: 60th Annual Assembly, 2007Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    In this study fatigue testing and defect assessment were carried out on specimens welded with robotic and manualwelding using fl ux cored (FCAW) and metal cored (MCAW) fi ller materials in order to study the effect of the weldingmethod on the fatigue strength and weld quality. Thirteen different batches were investigated of which two wasshot peened before fatigue testing. The local weld geometry was measured for all the specimens before testing.The specimens welded with fl ux cored weld wire showed the best fatigue strength, small defects and low residualstresses. Large scatter in the fatigue data is observed, especially when manual welding is employed. The few largestdefects were removed by the shot peening process, although small defects survived. This led to a smaller scatterin fatigue live for the shot peened specimens. Linear elastic fracture mechanics, LEFM, was employed for analysisof the fatigue test results. The fatigue life predictions using a 2D LEFM FE-model for simulating a continuous coldlap defect along the weld toe showed a qualitative agreement with the fatigue test results. The 2D analysis showedthat a continuous cold lap defect should be no more than 0.5 mm deep in order to comply with the requirement offatigue lives for normal weld quality according to the IIW design rules. For larger defects (> 0.8 mm) an increased toeradius will have a small effect on the fatigue strength. A 3D LEFM analysis of crack growth from a spatter-inducedcold lap defect was also carried out. This showed similar trends in crack growth compared to the 2D analysis ofa continuous cold lap, although the spatter-induced cold lap defect (semi-elliptical) had a longer fatigue life (x2.7),and hence is less dangerous from a fatigue point of view.

  • 230.
    Barsoum, Zuheir
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Samuelsson, Jack
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Fatigue and Quality Analysis of Cruciform Joints Welded with Different Methods, XIII-2136-062006Inngår i: International Institute of Welding: IIW 59th Annual Assembly, 2006Konferansepaper (Annet vitenskapelig)
  • 231.
    Barsoum, Zuheir
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Samuelsson, Jack
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Residual Stress Prediction and Relaxation in Welded Tubular Joints2006Inngår i: IIW Doc. No. XIII-2135-06/XV-1225-06, 2006Konferansepaper (Annet vitenskapelig)
  • 232.
    Barsoum, Zuheir
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Samuelsson, Jack
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
    Torsion Fatigue and Residual Stresses in Multi-Pass Welded Tubular Joint2005Inngår i: IIW Doc. No. XIII-2073-05, 2005Konferansepaper (Annet vitenskapelig)
  • 233.
    Barsoum, Zuheir
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Sperle, Jan Olof
    Mentorprogram för forskning kan ge kommersiella fördelar för svensk industri2009Inngår i: Svetsen, ISSN 0039-7091, Vol. 68, nr 2Artikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
  • 234.
    Bartonek, Åsa
    et al.
    Karolinska Institutet, Dept. of Women's and Child's Health.
    Wang, Ruoli
    KTH, Skolan för teknikvetenskap (SCI), Mekanik, Biomekanik.
    Eriksson, Marie
    Karolinska Institutet, Dept. of Women's and Children's Health.
    Gutierrez-Farewik, Elena
    KTH, Skolan för teknikvetenskap (SCI), Mekanik, Biomekanik. KTH, Skolan för teknikvetenskap (SCI), Mekanik, Strukturmekanik.
    Comparison of two carbon fibre spring orthoses' effect on gait in children with myelomeningocele2012Inngår i: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219Artikkel i tidsskrift (Fagfellevurdert)
  • 235.
    Batchuluun, Bolormaa
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Industriell teknik.
    Development of New Lifting Equipment for VPA Plates2016Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
    Abstract [en]

    This thesis explores how to develop new lifting equipment for the membrane and filter plates of the VPA (Metso) machine satisfying all the safety requirements. The VPA is a heavy duty machine with a number of plates, developed for filtration of minerals. The plates must be replaced or removed immediately once the wear has reached a given value or an error has been detected.

    The new lifting system differs to a great extent from conventional system in which a fiber strap was used; the designed lifting equipment comprises of a variety of parts resulting in a higher capacity to be used ín different situations safer and satisfies the vital requirements such as being a secure and cost-effective method, issued by the customers.

    Several solution proposals have been developed to offer better proposals before the final candidate has been selected and theoretically motivated with FEM analysis as well as analytical calculations.

    Keywords - VPA, membrane and filter plate, lifting equipment, pivot supporter hinge, safety, cost effective

  • 236. Bathelt, Jens
    et al.
    Jönsson, Anders
    How to Implement the Virtual Machine Concept Using xPC Target2003Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper presents an overview of the historical background of the virtual machine, containing a real control, a machine simulation and a 3D machine visualisation. This setup enables realistic system simulations, since the simulation input comes from a real control. The first known implementation of the virtual machine using xPC Target is described with an existing water jet cutting machine as an example. MathWorks products offer all necessary software for the presented setup, except the interface for the actual speed value from the simulated incremental encoder to the control. The unique xPC driver implementation, as a noninlined C-MEX S-Function, is presented at the end of this paper. The successful implementation of the virtual machine demonstrates the feasibility of the presented approach.

  • 237. Bathelt, Jens
    et al.
    Jönsson, Anders
    Bacs, Christian
    Kunz, Andreas
    Meier, Markus
    Conceptual Design Approach For Mechatronic Systems Controlled by a Programmable Logic Controller (PLC)2003Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Traditionally, the development of mechatronic systems starts with the mechanical design. Later electronic components and program logic for the product are added. This work proposes an improved interdisciplinary concurrent product development process with an enhanced function structure for the conceptual design phase. The new methodology is based on the German guideline VDI 2221 [1]. Transition conditions, time aspects and logic flow are added to the normal function structure. An example shows how to use the improved function structure. The enhanced function structure is used to derive the initial logic for the development of the PLC program controlling the machine later on. Since the extended function structure also covers the traditional information, it can still be used when building the assembly tree. By adding more information in the neutral function structure, the same information can be used for the mechanical design as well as for the electronic and logical design. The interdisciplinary communication and documentation among the engineers will be improved and errors in the concept will be detected earlier.

  • 238. Bathelt, Jens
    et al.
    Jönsson, Anders
    Bacs, Christian
    Meier, Markus
    Modularisierung SPS-gesteuerter mechatronischer Systeme2003Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Rein mechanische Lösungen werden zunehmend von mechatronischen Systemen abgelöst. Der X-by-wire Ansatz zeigt auch, dass der Anteil an mechanischen Teillösungen eines mechatronischen Systems immer weiter zurückgeht. Der vorliegende Beitrag skizziert einen Entwicklungsprozess für SPS-gesteuerte mechatronische Systeme, der dem immer wichtiger werdenden Steuerungsanteil Rechnung trägt. Dabei steht das parallele Arbeiten der Steuerungstechnik und der Konstruktion im Vordergrund, um die Entwicklungszeiten zu verkürzen und Fehler früher zu erkennen. Realisiert wird dies durch eine fachspezifische Modularisierung, deren erste Modulhierarchie als Ausgangslage der jeweiligen Disziplinen fungiert und somit einen parallelen Start ermöglicht. In dieser Arbeit werden Regeln vorgestellt, um die fachspezifischen Module von einer Funktionsstruktur abzuleiten. Abschliessend wird das Vorgehen anhand eines Industriebeispieles erläutert.

  • 239.
    Beaubert, F.
    et al.
    TEMPO, UVHC, Campus Mont Houy, 59313 Valenciennes Cedex 9, France.
    Pálsson, H.
    University of Iceland, Sæmundargötu 2, Reykjavík 101, Iceland.
    Lalot, S.
    EMPO, UVHC, Campus Mont Houy, Valenciennes Cedex 9, France.
    Choquet, Isabelle
    Högskolan Väst, Institutionen för teknik, matematik och datavetenskap, Avd för maskinteknik.
    Bauduin, H.
    EMPO, UVHC, Campus Mont Houy, Valenciennes Cedex 9, France.
    Fundamental mode of freely decaying laminar swirling flows2016Inngår i: Applied Mathematical Modelling, ISSN 0307-904X, E-ISSN 1872-8480, Vol. 40, nr 13-14, s. 6218-6233Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Abstract A detailed study of a swirling flow in a tube is presented in the first part of the paper. A simplified analytical solution of the governing equations indicates specific modes of the tangential velocity and that the decay of the swirl effect is exponential. The problem is then solved in three dimensions using computational fluid dynamics (CFD) and a comparison with analytical expressions shows that the CFD code is reliable in terms of accuracy. The CFD results confirm that a fundamental swirling mode is reached within a short distance from the inlet. The torque swirl number is introduced to physically estimate the intensity of the swirl. A companion value is given: it is the average deviation.

  • 240.
    Beccu, E.
    et al.
    AB Sandvik Rock Rools.
    Lundberg, Bengt
    Luleå tekniska universitet.
    Efficiency of percussive drilling of rock with dissipative joints1990Inngår i: International Journal of Impact Engineering, ISSN 0734-743X, E-ISSN 1879-3509, Vol. 9, nr 3, s. 277-287Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The nonlinear dissipative spring mass (NDSM) model for a percussive drill rod joint of the coupling sleeve (CS) type has been implemented into a Modula-2 program with the aid of which percussive drilling of rock is simulated. Transmission and dissipation of energy are first studied when a rectangular stress wave, generated through the impact by a uniform hammer, is transmitted through a single joint. The efficiency of energy transmission increases from 81 to 94% and the relative energy dissipation decreases from 8 to 1 or 2% when the length of the hammer varies from relatively short to relatively long. The effect of the joint preload is weak in the range from medium to relatively high preload. The efficiency of the percussive drilling process decreases with the number of joints but depends little on the joint preload. For soft rock, the efficiency increases with hammer length, whereas for medium and hard rock the dependence of efficiency on hammer length is not monotonic. This is because soft rock requires a long incident wave for efficient conversion of energy to work at the bit, whereas the reverse is true for hard rock. It is also found that the efficiency of the percussive drilling process may be considerably underestimated if the effects of each joint on the length and shape of the transmitted wave and of multiple reflections within the drill string are neglected

  • 241. Beccu, R.
    et al.
    Lundberg, Bengt
    Luleå tekniska universitet.
    Transmission and dissipation of stress wave energy at a percussive drill rod joint1987Inngår i: International Journal of Impact Engineering, ISSN 0734-743X, E-ISSN 1879-3509, Vol. 6, nr 3, s. 157-173Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Transmission and dissipation of stress wave energy at a percussive drill rod joint is determined for three joint types, three joint preload levels, three hammer lengths ( incident wave lengths) and a range of impact velocities ( incident wave amplitudes). The energies of the incident, reflected and transmitted waves are evaluated from measured strains, and then the dissipated energy is determined as the deficit of energy in the two latter waves compared with the first. The accuracy needed is obtained by introducing a compensation factor and determining its value from the requirement of momentum conservation. The experimental results for threaded standard joints are compared with experimental results for threadless dummy joints, made in one piece, and also with theoretical results. The latter are based on one model which represents the joint as a well on a one- dimensional elastic rod (characteristics impedance or CI model) and on another model which represents the joint as a rigid mass between one-dimensional elastic rods (rigid mass or RM model). For the joints 70-100% of the incident wave energy is transmitted and 0-20% is dissipated. The corresponding figures for the dummies are 90-100% and (±)1%, repectively. The latter figure indicates the inaccuracy in the measurement and evaluation procedures. The two models agree fairly well with the dummies. Under certain conditions they also give reasonably accurate predictions for the energy transmitted through a joint. As they sometimes give quite inaccurate results for energy transmission and furthermore fail to predict energy dissipation they need be refined.

  • 242.
    Beccu, Rainer
    Luleå tekniska universitet.
    Dissipation in drill rod joints1989Licentiatavhandling, monografi (Annet vitenskapelig)
  • 243. BECKENBAUER, THOMAS
    et al.
    JEAN, PHILIPPE
    KROPP, WOLFGANG
    STEINAUER, BERNHARD
    UECKERMANN, ANDREAS
    SCHULZE, CHRISTIAN
    MEYER, ANDRE
    Finnveden, Svante
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strukturakustik.
    Fahrbahnbelag und Verfahren zur Herstellung desselben2008Patent (Annet (populærvitenskap, debatt, mm))
  • 244.
    Bekele, Abiy
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Birgisson, Björn
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap. KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Vägtekniks laboratorium.
    Rydén, Nils
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Gudmarsson, Anders
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Slow dynamic diagnosis of asphalt concrete specimen to determine level of damage caused by static low temperature conditioning2017Inngår i: 43rd Annual Review of Progress in Quantitative Nondestructive Evaluation, American Institute of Physics (AIP), 2017, Vol. 1806, artikkel-id 080012Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The phenomenon of slow dynamics has been observed in a variety of materials which are considered as relatively homogeneous that exhibit nonlinearity due to the presence of defects or cracks within them. Experimental realizations in previous work suggest that slow dynamics can be in response to acoustic drives with relatively larger amplitude as well as rapid change of temperature. Slow dynamics as a nonlinear elastic response of damaged materials is manifested as a sharp drop and then recovery of resonance frequency linearly with logarithmic time. In this work, slow dynamics recovery is intended to be used as a means of identifying and evaluating thermal damage on an asphalt concrete specimen. The experimental protocol for measuring slow dynamics is based on the technique of nonlinear resonance spectroscopy and is set up with non-contact excitation using a loud speaker and the data acquisition tool box of Matlab. Sweeps of frequency with low amplitude are applied in order to probe the specimen at its linear viscoelastic state. The drop and then recovery in fundamental axially symmetric resonance frequency is observed after the specimen is exposed to sudden temperature change. The investigation of the viscoelastic contribution to the change in resonance frequency and slow dynamics can help identify micro-damage in asphalt concrete samples.

  • 245.
    Bellani, Gabriele
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Bach, Roland
    Lundell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Söderberg, L. Daniel
    KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Experimental study of filtration of fiber suspensions: Part II: combined PIV and pressure drop measurements2011Rapport (Annet vitenskapelig)
    Abstract [en]

    The filtration of a fiber suspension has been studied experimentally. Typical applications where pressure filtration occurs are: papermaking, air cleaners, production of composite materials, etc. In particular, in papermaking, the quality of the final product depends on the fiber orientation and mass distribution in the filtered material. Micro-variations of these properties can strongly affect the quality of the final product and they can occur during filtration, thus it is important to predict how this can happen. However, this is not an easy task, first because the filtered cake is a non-homogeneous compressible porous media, second because the filtration flow is non-stationary, since the cake is continuously evolving in time. Therefore in this work we focus on the filtration flow through formed steady fiber networks. For each grammage (i.e. mass of fibers per unit area), we simultaneously measure the pressure drop across the network and velocity field on top and below the fiber network using Particle Image Velocimetry (PIV). Compression of the fiber network can also be extracted from the PIV images. Normalized filtration resistance was found to be decreasing with increasing network thickness, as well as network compressibility. From the PIV data the influence of the formed fiber network on the flow field was analyzed and characteristic scales of the flow structures are quantified.

  • 246.
    Bellani, Gabriele
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Collignon, Audric
    Variano, Evan A.
    Turbulence modulation and rotational dynamics of large nearly neutrally buoyant particles in homogeneous isotropic turbulence2012Rapport (Annet vitenskapelig)
    Abstract [en]

    This paper is an experimental investigation of turbulence modulation effects by Taylor-scale size particles in the dilute regime. Experiments are performed on a turbulence tank able to provide Homogeneous Isotropic Turbulence at Reλ ≈ 270. A novel experimental technique capable of simultaneously measuring rotational rates of arbitrarily shaped particles and fluid velocity using standard Stereoscopic Particle Image Velocimetry (Stereo-PIV) and Index-of-Refracion matching is presented here. Particles of the same IoR of water with embedded tracers allowed the measurement of the velocity of the portion of particles in the measurement plane. A novel algorithm based on the assumption of solid body rotation, is then used to extract particle rotation rates. We compare the results from two particle shapes to the single phase measurements: spherical and ellipsoidal particles with aspect ratio 2. It is found that spherical particles provide a 15% turbulence reduction, about five times more than what is provided by ellipsoidal particles at the same volume fraction (φv ≈ 0.1%), and with less particle surface area available. These result suggest that there might be an turbulence production mechanism for ellipsoidal particles that is not present for spheres. This hypothesis is supported by spectral analysis. Pivoting effect is observed for both spherical and ellipsoidal particles, but for the latter, the reduction in the small wavenumber region is less evident. Preliminary results of statistics of rotational rates shows that ellipsoidal particles tend to have an enhanced rotational velocity as compared to spheres.

  • 247. Bellani, Gabriele
    et al.
    Imagawa, K.
    KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Tammisola, O.
    Lundell, Fredrik
    Higuchi, H.
    Hayase, T.
    Measurement-Integrated simulations and Kalman filter applied to a turbulent co-flowing jet2010Rapport (Annet vitenskapelig)
    Abstract [en]

    This paper deals with the experimental evaluation of a flow analysis system based on the integration between an under-resolved Navier-Stokes simulation and experimental measurements with the mechanism of feedback (referred to as Measurement-Integrated simulation), applied to the case of a planar turbulent co-flowing jet. The experiments are performed with inner-to-outer-jet velocity ratio around 2 and the Reynolds number based on the inner-jet heights about 10000. The measurement system is a high-speed PIV, which provides timeresolved data of the flow-field, on a field of view which extends to 20 jet heights downstream the jet outlet. The experimental data can thus be used both for providing the feedback data for the simulations and for validation of the M-Isimulations over a wide region. The effect of reduced data-rate and spatial extent of the feedback was investigated. Then, to deal with the reduced data different feedback strategies were tested. It was found that for small data-rate reduction the results are basically equivalent to the case of full-information feedback but as the feedback data-rate is reduced further the error increases and tend to be localized in regions of high turbulent activity. Moreover, it is found that the spatial distribution of the error looks qualitatively different for different feedback strategies. Feedback gain distributions calculated by optimal control theory are presented and proposed as a mean to make it possible t operform MI-simulations based on localized measurements only. So far, we have not been able to low error between measurements and simulations by using these gain distributions.

  • 248.
    Bellani, Gabriele
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Lundell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Söderberg, L. Daniel
    KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Experimental study of filtration of fiber suspensions: Part I: fluid velocity and fluid-fiber interactionmeasurements2008Rapport (Annet vitenskapelig)
    Abstract [en]

    A study of the flow in the direct vicinity of a forming wire and a fiber network during forming is reported. The measurements are performed with Particle Image Velocimetry in a scaled system. Index-of-refraction matching is used to gain optical access to the flow. Time resolved measurements of the flow velocity in the vertical and horizontal direction is obtained in a plane with a size of 60×40 fiber diameters. Data is obtained for three drainage velocities and two different lengths of the fibers. The relative level of the velocity fluctuationsis found to decrease with drainage velocity and is higher in the flow above a network mat of shorter fibers compared to the network made of longer fibers

  • 249.
    Bellenger, Adrian
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.), Hållfasthetslära (Avd.).
    Sensitivity analysis and uncertainty propagation through new lifetime prediction model of welded metal assemblies2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Fatigue failures are critical in armored vehicle design but the lack of knowledge on fatigue phenomena forces the use of large safety factors which induces weight and costs increase. This master's thesis has been driven by the will of improving the simulation of low cycle fatigue phenomenon of metal parts and welded assemblies in order to reduce safety margins. Two distinct but complementary paths are investigated: improvement of the fatigue simulation model and awareness of fatigue phenomenon dispersion. Firstly, the implementation of a new lifetime prediction model is proposed based on the ONERA fatigue criterion that has been developed for both low cycle and high cycle fatigue phenomena. The method introduced in this report is composed of the identification of material behavior laws, the simulation of experimental tests by finite element analysis and the calibration of fatigue criterion parameters. Low cycle fatigue experimental tests (uniaxial traction-compression tests) data for base metal and welded samples are used for the identifications. The material behavior follows Chaboche's theory and integrates two nonlinear kinematic hardenings and one isotropic hardening. However, the use of isotropic hardening is nearly impossible in practice due to computation cost and it has been decided to work with stabilized cycle laws. The finite element analyses are controlled by tests stresses. The ONERA fatigue criterion is only partially identified because the full identification requires additional experimental tests that have not been performed yet. Despite those simplifications, the lifetime prediction value is accurate and better than the ones given by previously used model. The process still has to be validated on other geometries. During the implementation of the whole process, elastic limit and fatigue limit appeared to be the most influential variables and the refinement of their values will increase the model's accuracy. Secondly, it is well known that fatigue phenomenon shows high dispersion. One way to take into account this aspect is to assign a stochastic aspect to lifetime prediction model variables and propagate it through the model. However, the combination with finite element analysis is impossible because of the computation time cost of each simulation forcing the use of metamodelling methods. PhimecaSoft offers to gather in a user-friendly interface a broad range of methods to execute uncertainties propagations in structural design environment. A coupling with in-house fatigue model has been set up to study the influence of model variables on the lifetime. The definition of the probability laws of the input variables is crucial. In the framework of this thesis it has been necessary to truncate the laws to keep plausible dispersions of the input variables and realistic values of the lifetime. Different functionalities of PhimecaSoft have been investigated such as: the use of Sobol's coefficients for global sensitivity analysis or the generation of metamodels. Reliability analysis is also part of PhimecaSoft and can be done whether by simulations methods or approximation methods. The use of reliability index is encouraged in the future to move from safety factor's based design toward reliability based design optimization. This second part of the thesis confirms that the elastic limit and fatigue limit are the most influential variables of the problem.

  • 250.
    Benckert, Lars
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    A method to resolve the 180° ambiguity in speckle photography1991Inngår i: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 30, nr 4, s. 376-378Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    A new way of resolving the 180° ambiguity in speckle photography is presented. Results from a study of the deformation of a wooden block caused by drying illustrates the method

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