DTU Orbit RSS Feed
http://orbit.dtu.dk/en/publishers/technical-university-of-denmark-dtu(f7c040ab-194a-4da4-b458-670da24b2a08)/search/publications.html?page=4
RSS FeedTue, 17 May 2016 12:42:24 GMT2016-05-17T12:42:24ZReal Time Structured Light and Applications
http://orbit.dtu.dk/en/publications/real-time-structured-light-and-applications(61fd47e5-9e05-4ed7-abf6-feadbe572023).html
<div style='font-size: 9px;'><div class="rendering rendering_publication rendering_publication_short rendering_bookanthology rendering_short rendering_bookanthology_short"><h2 class="title"><a rel="BookAnthology" href="http://orbit.dtu.dk/en/publications/real-time-structured-light-and-applications(61fd47e5-9e05-4ed7-abf6-feadbe572023).html" class="link"><span>Real Time Structured Light and Applications</span></a></h2><a rel="Person" href="http://orbit.dtu.dk/en/persons/jakob-wilm(6885ae34-72fa-493c-96db-7e24dd0a5a62).html" class="link person"><span>Wilm, J.</span></a>, <a rel="Person" href="http://orbit.dtu.dk/en/persons/henrik-aanaes(82129afb-048a-424a-ba22-419bd0bab56f).html" class="link person"><span>Aanæs, H.</span></a>, <a rel="Person" href="http://orbit.dtu.dk/en/persons/rasmus-larsen(b3ea098f-fc7a-48a0-94ae-ae033577d7f1).html" class="link person"><span>Larsen, R.</span></a> & <a rel="Person" href="http://orbit.dtu.dk/en/persons/rasmus-reinhold-paulsen(d672590e-6b1e-4248-b5d7-0ecdb8553716).html" class="link person"><span>Paulsen, R. R.</span></a> <span class="date">2016</span> Kgs. Lyngby: <a rel="Publisher" href="http://orbit.dtu.dk/en/publishers/technical-university-of-denmark-dtu(f7c040ab-194a-4da4-b458-670da24b2a08).html" class="link"><span>Technical University of Denmark (DTU)</span></a>. <span class="numberofpages">82 p.</span> (DTU Compute PHD-2015; No. 400).<p class="type"><span class="type_family">Publication<span class="type_family_sep">: </span></span><span class="type_classification_parent">Research<span class="type_parent_sep"> › </span></span><span class="type_classification">Ph.D. thesis – Annual report year: 2016</span></p></div><div class="rendering rendering_publication rendering_publication_detailsportal rendering_bookanthology rendering_detailsportal rendering_bookanthology_detailsportal"><div class="abstract"><div class="textblock">Structured light scanning is a versatile method for 3D shape acquisition. While much faster than most competing measurement techniques, most high-end structured light scans still take in the order of seconds to complete. <br /><br />Low-cost sensors such as Microsoft Kinect and time of flight cameras have made 3D sensor ubiquitous and have resulted in a vast amount of new applications and methods. However, such low-cost sensors are generally limited in their accuracy and precision, making them unsuitable for e.g. accurate tracking and pose estimation.<br /><br />With recent improvements in projector technology, increased processing power, and methods presented in this thesis, it is possible to perform structured light scans in real time with 20 depth measurements per second. This offers new opportunities for studying dynamic scenes, quality control, human-computer interaction and more.<br /><br />This thesis discusses several aspects of real time structured light systems and presents contributions within calibration, scene coding and motion correction aspects. The problem of reliable and fast calibration of such systems is addressed with a novel calibration scheme utilising radial basis functions [Contribution B]. A high performance flexible open source software toolkit is presented [Contribution C], which makes real time scanning possible on commodity hardware. Further, an approach is presented to correct for motion artifacts in dynamic scenes [Contribution E].<br /><br />An application for such systems is presented with a head tracking approach for medical motion correction [Contribution A, F]. This aims to solve the important problem of motion artifacts, which occur due to head movement during long acquisition times in MRI and PET scans. In contrast to existing methods, the one presented here is MRI compatible [Contribution D], not dependent on fiducial markers, and suitable for prospective correction. <br /><br />Factors contributing to accuracy and precision of structured light systems are investigated with a study of performance factors [Contribution G]. This is also done in the context of biological tissue, which exhibit subsurface effects and other undesirable effects [Contribution H], and it is shown that this error is to a large extent deterministic and can be corrected.<br /></div></div><div class="phddissertation"><table class="properties"><tbody><tr class="language"><th>Original language</th><td>English</td></tr></tbody></table><table class="properties"><tbody><tr><th>Place of Publication</th><td>Kgs. Lyngby</td></tr><tr><th>Publisher</th><td><a rel="Publisher" href="http://orbit.dtu.dk/en/publishers/technical-university-of-denmark-dtu(f7c040ab-194a-4da4-b458-670da24b2a08).html" class="link"><span>Technical University of Denmark (DTU)</span></a></td></tr><tr><th>Number of pages</th><td>82</td></tr><tr class="status"><th>State</th><td><span class="prefix">Published - </span><span class="date">2016</span></td></tr></tbody></table></div> <table class="properties"><tbody><tr><th>Name</th><td>DTU Compute PHD-2015</td></tr><tr><th>Number</th><td>400</td></tr><tr><th>ISSN (print)</th><td>0909-3192</td></tr></tbody></table></div></div>Thu, 31 Dec 2015 23:00:00 GMThttp://orbit.dtu.dk/en/publications/real-time-structured-light-and-applications(61fd47e5-9e05-4ed7-abf6-feadbe572023).html2015-12-31T23:00:00ZThermal Performance Characterization using Time Series Data - IEA EBC Annex 58 Guidelines
http://orbit.dtu.dk/en/publications/thermal-performance-characterization-using-time-series-data--iea-ebc-annex-58-guidelines(efa4fbc1-f244-4955-9c89-9305fee3993b).html
<div style='font-size: 9px;'><div class="rendering rendering_publication rendering_publication_short rendering_bookanthology rendering_short rendering_bookanthology_short"><h2 class="title"><a rel="BookAnthology" href="http://orbit.dtu.dk/en/publications/thermal-performance-characterization-using-time-series-data--iea-ebc-annex-58-guidelines(efa4fbc1-f244-4955-9c89-9305fee3993b).html" class="link"><span>Thermal Performance Characterization using Time Series Data - IEA EBC Annex 58 Guidelines</span></a></h2><a rel="Person" href="http://orbit.dtu.dk/en/persons/henrik-madsen(458e950b-adfd-4f2d-8d0d-ef39dee24bea).html" class="link person"><span>Madsen, H.</span></a>, <a rel="Person" href="http://orbit.dtu.dk/en/persons/peder-bacher(c0c28383-2363-4876-8bdc-450ca6c749c1).html" class="link person"><span>Bacher, P.</span></a>, Bauwens, G., Deconinck, A-H., Reynders, G., Roels, S., Himpe, E. & Lethé, G. <span class="date">2015</span> <a rel="Publisher" href="http://orbit.dtu.dk/en/publishers/technical-university-of-denmark-dtu(f7c040ab-194a-4da4-b458-670da24b2a08).html" class="link"><span>Technical University of Denmark (DTU)</span></a>. <span class="numberofpages">83 p.</span> (DTU Compute-Technical Report-2015; No. 8).<p class="type"><span class="type_family">Publication<span class="type_family_sep">: </span></span><span class="type_classification_parent">Research<span class="type_parent_sep"> › </span></span><span class="type_classification">Report – Annual report year: 2015</span></p></div><div class="rendering rendering_publication rendering_publication_detailsportal rendering_bookanthology rendering_detailsportal rendering_bookanthology_detailsportal"><div class="abstract"><div class="textblock">This document presents guidelines for using time series analysis methods, models and tools for estimating the thermal performance of buildings and building components. The thermal performance is measured as estimated parameters of a model, or parameters derived from estimated parameters of a model. A special focus will be on estimating the Heat Loss Coefficient (HLC) and gA-value. Provided in the guidelines are modelling procedures with which consistent results for estimation of energy performance of buildings and building components can be achieved.<br /><br />These guidelines start with simple (non-dynamical) steady state models where the parameters are found using classical methods for linear regression. Such steady state techniques provide sub-optimal use of the information embedded in the data and provides information only about the HLC and gA-values. <br /><br />Next the guidelines consider dynamical models. Firstly, linear input-output models are considered. More specifically we will consider the class of AutoRegressive with eXogenous input (ARX) (p) models. These models provides information about the HLC and gA-values, and information about the dynamics (most frequently described as time-constants for the system).<br /><br />Finally, grey-box models are considered. This class of models is formulated as state space models which are able to provide rather detailed information about the internal physical parameters of a construction. This class of models bridges the gap between physical and statistical modelling. A grey-box model is formulated as a continuous time model for the states of the system, together with a discrete set of equations describing how the measurements are linked to the states. The frequently used so-called RC-network models belongs to the class of linear greybox models. However, advanced constructions, like a wall with PV-integration or a complex building with a lot of glass, often calls for a description of nonlinear phenomena. This can be facilitated by the class of non-linear grey-box models. <br /><br />It is assumed that data is available as time series of measurements. Hence it should be noticed that the important steps of experimental design and setting up the experiment have been conducted.</div></div><div class="scientificreport"><table class="properties"><tbody><tr class="language"><th>Original language</th><td>English</td></tr></tbody></table><table class="properties"><tbody><tr><th>Publisher</th><td><a rel="Publisher" href="http://orbit.dtu.dk/en/publishers/technical-university-of-denmark-dtu(f7c040ab-194a-4da4-b458-670da24b2a08).html" class="link"><span>Technical University of Denmark (DTU)</span></a></td></tr><tr><th>Number of pages</th><td>83</td></tr><tr class="status"><th>State</th><td><span class="prefix">Published - </span><span class="date">2015</span></td></tr></tbody></table></div> <table class="properties"><tbody><tr><th>Name</th><td>DTU Compute-Technical Report-2015</td></tr><tr><th>Number</th><td>8</td></tr><tr><th>ISSN (print)</th><td>1601-2321</td></tr></tbody></table></div></div>Wed, 31 Dec 2014 23:00:00 GMThttp://orbit.dtu.dk/en/publications/thermal-performance-characterization-using-time-series-data--iea-ebc-annex-58-guidelines(efa4fbc1-f244-4955-9c89-9305fee3993b).html2014-12-31T23:00:00ZSecurity Protocols: Specification, Verification, Implementation, and Composition
http://orbit.dtu.dk/en/publications/security-protocols-specification-verification-implementation-and-composition(3c09a1b3-4c96-4bff-8657-2edb6858b6b1).html
<div style='font-size: 9px;'><div class="rendering rendering_publication rendering_publication_short rendering_bookanthology rendering_short rendering_bookanthology_short"><h2 class="title"><a rel="BookAnthology" href="http://orbit.dtu.dk/en/publications/security-protocols-specification-verification-implementation-and-composition(3c09a1b3-4c96-4bff-8657-2edb6858b6b1).html" class="link"><span>Security Protocols: Specification, Verification, Implementation, and Composition</span></a></h2><a rel="Person" href="http://orbit.dtu.dk/en/persons/omar-almousa(aac50d12-94eb-45d6-85e4-d9cdaf5b53a3).html" class="link person"><span>Almousa, O.</span></a>, <a rel="Person" href="http://orbit.dtu.dk/en/persons/sebastian-alexander-moedersheim(21eb3855-68a7-4647-a3a0-8526af03169f).html" class="link person"><span>Mödersheim, S. A.</span></a> & <a rel="Person" href="http://orbit.dtu.dk/en/persons/hanne-riis-nielson(44a7d08e-b083-4419-a466-8f4392a7112f).html" class="link person"><span>Nielson, H. R.</span></a> <span class="date">2016</span> Kgs. Lyngby: <a rel="Publisher" href="http://orbit.dtu.dk/en/publishers/technical-university-of-denmark-dtu(f7c040ab-194a-4da4-b458-670da24b2a08).html" class="link"><span>Technical University of Denmark (DTU)</span></a>. <span class="numberofpages">164 p.</span> (DTU Compute PHD-2015; No. 391).<p class="type"><span class="type_family">Publication<span class="type_family_sep">: </span></span><span class="type_classification_parent">Research<span class="type_parent_sep"> › </span></span><span class="type_classification">Ph.D. thesis – Annual report year: 2016</span></p></div><div class="rendering rendering_publication rendering_publication_detailsportal rendering_bookanthology rendering_detailsportal rendering_bookanthology_detailsportal"><div class="abstract"><div class="textblock">An important aspect of Internet security is the security of cryptographic protocols that it deploys. We need to make sure that such protocols achieve their goals, whether in isolation or in composition, i.e., security protocols must not suffer from any aw that enables hostile intruders to break their security. Among others, tools like OFMC [MV09b] and Proverif [Bla01] are quite efficient for the automatic formal verification of a large class of protocols. These tools use different approaches such as symbolic model checking or static analysis. Either approach has its own pros and cons, and therefore, we need to combine their strengths. Moreover, we need to ensure that the protocol implementation coincides with the formal model that we verify using such tools. <br /><br />This thesis shows that we can simplify the formal verification of protocols in several ways. First, we introduce an Alice and Bob style language called SPS (Security Protocol Specification) language, that enables users, without requiring deep expertise in formal models from them, to specify a wide range of real-world protocols in a simple and intuitive way. Thus, SPS allows users to verify their protocols using different tools, and generate robust implementations in different languages. Moreover, SPS has the "ultimate” formal semantics for Alice and Bob notation in the presence of an arbitrary set of cryptographic operators and their algebraic theory. Despite its generality, this semantics is mathematically simpler than any previous attempt.<br /><br />Second, we introduce two types of relative soundness results that reduce complex verification problems into simpler ones. The first kind is typing results showing that if a security protocol, that fulfills a number of sufficient conditions, has an attack then it has a well-typed attack. The second kind considers the parallel composition of protocols, showing that if the parallel composition of two protocols, that fulfill a number of sufficient conditions, allows for an attack then one of the protocols, at least, has an attack in isolation. In fact, we unify and generalize over prior relative soundness results. The most important generalization is the support for all security properties of the geometric fragment proposed by [Gut14].<br /></div></div><div class="phddissertation"><table class="properties"><tbody><tr class="language"><th>Original language</th><td>English</td></tr></tbody></table><table class="properties"><tbody><tr><th>Place of Publication</th><td>Kgs. Lyngby</td></tr><tr><th>Publisher</th><td><a rel="Publisher" href="http://orbit.dtu.dk/en/publishers/technical-university-of-denmark-dtu(f7c040ab-194a-4da4-b458-670da24b2a08).html" class="link"><span>Technical University of Denmark (DTU)</span></a></td></tr><tr><th>Number of pages</th><td>164</td></tr><tr class="status"><th>State</th><td><span class="prefix">Published - </span><span class="date">2016</span></td></tr></tbody></table></div> <table class="properties"><tbody><tr><th>Name</th><td>DTU Compute PHD-2015</td></tr><tr><th>Number</th><td>391</td></tr><tr><th>ISSN (print)</th><td>0909-3192</td></tr></tbody></table></div></div>Thu, 31 Dec 2015 23:00:00 GMThttp://orbit.dtu.dk/en/publications/security-protocols-specification-verification-implementation-and-composition(3c09a1b3-4c96-4bff-8657-2edb6858b6b1).html2015-12-31T23:00:00ZA methodological approach to designing sewer system control
http://orbit.dtu.dk/en/publications/a-methodological-approach-to-designing-sewer-system-control(1b2b2ebd-225c-48da-bffa-13431f39d6fa).html
<div style='font-size: 9px;'><div class="rendering rendering_publication rendering_publication_short rendering_bookanthology rendering_short rendering_bookanthology_short"><h2 class="title"><a rel="BookAnthology" href="http://orbit.dtu.dk/en/publications/a-methodological-approach-to-designing-sewer-system-control(1b2b2ebd-225c-48da-bffa-13431f39d6fa).html" class="link"><span>A methodological approach to designing sewer system control</span></a></h2><a rel="Person" href="http://orbit.dtu.dk/en/persons/ane-loft-mollerup(64053613-5483-4322-bc4f-c11c6120d204).html" class="link person"><span>Mollerup, A. L.</span></a>, <a rel="Person" href="http://orbit.dtu.dk/en/persons/gurkan-sin(4c35984e-28c5-43c9-9a4b-c7ac589bf597).html" class="link person"><span>Sin, G.</span></a>, <a rel="Person" href="http://orbit.dtu.dk/en/persons/peter-steen-mikkelsen(5d6db083-1bf0-4341-bc4c-ac2f83e29354).html" class="link person"><span>Mikkelsen, P. S.</span></a>, Johansen, N. B. & Thornberg, D. <span class="date">2015</span> Kgs. Lyngby: <a rel="Publisher" href="http://orbit.dtu.dk/en/publishers/technical-university-of-denmark-dtu(f7c040ab-194a-4da4-b458-670da24b2a08).html" class="link"><span>Technical University of Denmark (DTU)</span></a>. <span class="numberofpages">207 p.</span><p class="type"><span class="type_family">Publication<span class="type_family_sep">: </span></span><span class="type_classification_parent">Research<span class="type_parent_sep"> › </span></span><span class="type_classification">Ph.D. thesis – Annual report year: 2015</span></p></div><div class="rendering rendering_publication rendering_publication_detailsportal rendering_bookanthology rendering_detailsportal rendering_bookanthology_detailsportal"><div class="abstract"><div class="textblock">When designing sewer system control, there is a lack of methodology and tools that can aid in the design process. In 2004 the PASST1 framework was presented that focuses on determining the potential for control in sewer sys-tem operation. However, for the actual design of control systems urban drain-age planners still have to rely on their operational knowledge combined with model simulations and trial and error. This is an inefficient process where the final design largely depends on the urban drainage planner’s knowledge about the system dynamics and control in general. The motivation for this thesis was therefore the wish for a methodological approach to sewer system control design. Using a case study the following research hypothesis was tested in this thesis:<br />Using classical and modern control theory, a methodological approach can be derived for designing sewer system control. This can aid urban drainage planner and other professionals in the planning phase of sewer system con-trol design and effectively contribute to find novel control solution.<br />It was investigated if the established methodology used in classic control the-ory for process control design can be applied meaningfully to the sewer sys-tem. As the methodology takes its basis in a hierarchical decomposition of the control problem based on time-scale, it was also investigated if sewer sys-tem control can be decomposed in a similar manner.From a review of existing control systems for sewer systems in Europe, it was concluded that sewer system control can also be decomposed in a hierarchical manner based on differences in time-scale. The proposed time-scale dependent hierarchy for sewer system control contains four layers that each handles their own dedicated task. From the bottom and up they are: 1) the regulatory control layer, 2) the coordinating control layer, 3) the optimisation layer and 4) the management of objectives layer.<br />The time-scale dependent hierarchy for sewer system control is put into a framework that also contains a terminology related to control. In this way the1 Planning aid for sewer system real time controlvframework can help to compare different control system solutions and facili-tate a clear communication between different professions and disciplines working together in sewer system control design.<br />Starting from the hierarchical decomposition of sewer system control in lay-ers, a stepwise approach to design sewer system control was proposed and followed. The individual layers of the hierarchy were designed one by one for a case study in Copenhagen, with the methods and tools taken from both clas-sical and modern control theory.<br />The tools of classical control theory are developed for systems that can be approximated by linear models. The main challenge of using classical control theory on the case study was therefore the transient nature and the non-linearity of the sewer system dynamics. The methodology was adapted, by linearizing the sewer system model at various points in time, creating a step-wise linear model. The results of the linearization showed that the sewer sys-tem dynamics could be divided into four phases, characterised by the follow-ing operation modes: dry weather, filling, saturation and emptying. Having obtained a piece-wise linear model for each of the operational modes, the tools from classical control theory, such as the calculation of the condition number and the relative gain array, could be successfully applied to the sewer system. Based on the results a pairing between the measurements variables and the actuators could be suggested.<br />Having proposed to decompose the sewer system control in a hierarchical manner, it became necessary to investigate the role of the lowest layer in the hierarchy, which is the regulatory control layer. Traditionally the role of the regulatory layer is to reject disturbances and track the setpoints, and the sim-plest form of regulatory control has just constant setpoints. However, in a transient system like the sewer system, the setpoints may change dramatically and rapidly. Therefore the regulatory control layer may not have the same functionality when designed for the sewer system. From the application of the classical control theory it was found that the system dynamics could be de-scribed by four operational modes, and instead of a fixed setpoint the regula-tory control layer needs changing setpoints, according to the operational modes. These can either be fed from a coordinating control layer or from an online optimisation.<br />To design an optimisation to feed setpoints to the regulatory control layer, modern control theory was applied to the case study. The optimisation was tested when it acted directly on the actuators and when it acted on the regula-vitory control layer. The two optimisation based control structures were evalu-ated from a one year simulation and the results showed that there was little difference in the performance. The optimisation based control structures were also compared to the existing control and the regulatory control with set-points coming from the coordinating control layer, and here the latter showed the best performance. This was not unexpected, since the true potential of having optimisation arises, when a system has many control loops with limit-ing constraints and/or changing prioritisation between them. The results showed that for small sewer systems, where the complexity is limited, it is not necessarily the best option to implement advanced optimisation based control systems. Therefore it is also advisable to approach the design of a control system in a methodological manner, where the design and evaluation can be done step by step.<br />Based on the experiences gained from designing sewer system control sys-tems for the case study, a systematic methodology for designing sewer sys-tem control is proposed that combined the steps, control and optimisation tools and methods used throughout the thesis. The proposed methodology provides a basis for gathering experiences with sewer system control design and knowledge sharing; and will help generate control systems of the future that are more robust, more structured, have a better performance and are easi-er to maintain.</div></div><div class="phddissertation"><table class="properties"><tbody><tr class="language"><th>Original language</th><td>English</td></tr></tbody></table><table class="properties"><tbody><tr><th>Place of Publication</th><td>Kgs. Lyngby</td></tr><tr><th>Publisher</th><td><a rel="Publisher" href="http://orbit.dtu.dk/en/publishers/technical-university-of-denmark-dtu(f7c040ab-194a-4da4-b458-670da24b2a08).html" class="link"><span>Technical University of Denmark (DTU)</span></a></td></tr><tr><th>Number of pages</th><td>207</td></tr><tr class="status"><th>State</th><td><span class="prefix">Published - </span><span class="date">2015</span></td></tr></tbody></table></div></div></div>Wed, 31 Dec 2014 23:00:00 GMThttp://orbit.dtu.dk/en/publications/a-methodological-approach-to-designing-sewer-system-control(1b2b2ebd-225c-48da-bffa-13431f39d6fa).html2014-12-31T23:00:00ZNumerical simulation of viscoelastic free‐surface flows using a streamfunction/log‐conformation formulation and the volume‐of‐fluid method
http://orbit.dtu.dk/en/publications/numerical-simulation-of-viscoelastic-freesurface-flows-using-a-streamfunctionlogconformation-formulation-and-the-volumeoffluid-method(3c921ed6-6981-4ee6-9751-5d41dec05cbc).html
<div style='font-size: 9px;'><div class="rendering rendering_publication rendering_publication_short rendering_bookanthology rendering_short rendering_bookanthology_short"><h2 class="title"><a rel="BookAnthology" href="http://orbit.dtu.dk/en/publications/numerical-simulation-of-viscoelastic-freesurface-flows-using-a-streamfunctionlogconformation-formulation-and-the-volumeoffluid-method(3c921ed6-6981-4ee6-9751-5d41dec05cbc).html" class="link"><span>Numerical simulation of viscoelastic free‐surface flows using a streamfunction/log‐conformation formulation and the volume‐of‐fluid method</span></a></h2><a rel="Person" href="http://orbit.dtu.dk/en/persons/raphael-benjamin-comminal(d1438993-c3aa-43b5-8f3d-d5baed49b637).html" class="link person"><span>Comminal, R. B.</span></a>, <a rel="Person" href="http://orbit.dtu.dk/en/persons/jesper-henri-hattel(cc43ac84-8b15-435d-a8b8-343c75c257db).html" class="link person"><span>Hattel, J. H.</span></a>, <a rel="Person" href="http://orbit.dtu.dk/en/persons/nini-pryds(95344b1f-2936-4299-9fad-3d932de62b99).html" class="link person"><span>Pryds, N.</span></a> & <a rel="Person" href="http://orbit.dtu.dk/en/persons/jon-spangenberg(d6472dc2-035e-4d54-b7ee-96256e30814c).html" class="link person"><span>Spangenberg, J.</span></a> <span class="date">2015</span> Kgs. Lyngby: <a rel="Publisher" href="http://orbit.dtu.dk/en/publishers/technical-university-of-denmark-dtu(f7c040ab-194a-4da4-b458-670da24b2a08).html" class="link"><span>Technical University of Denmark (DTU)</span></a>. <span class="numberofpages">234 p.</span><p class="type"><span class="type_family">Publication<span class="type_family_sep">: </span></span><span class="type_classification_parent">Research<span class="type_parent_sep"> › </span></span><span class="type_classification">Ph.D. thesis – Annual report year: 2015</span></p></div><div class="rendering rendering_publication rendering_publication_detailsportal rendering_bookanthology rendering_detailsportal rendering_bookanthology_detailsportal"><div class="abstract"><div class="textblock">This thesis presents a new numerical algorithm for the simulation of two‐dimensional multiphase viscoelastic
flows. The simulation of viscoelastic flows has both a scientific importance and practical implications in polymer
processing. This work has put the emphasis on the extrusion of polymeric materials, where viscoelastic effects
cause dynamical instabilities, despite the very simple geometry. This thesis reviews the popular differential
constitutive models derived from molecular theories of dilute polymer solutions, polymer networks, and
entangled polymer melts, as well as the inelastic phenomenological models describing shear–thinning and
viscoplastic (yield stress) fluids, based on the generalized Newtonian fluid model. In addition, the numerical
issues related to the high Weissenberg number problem, and its remedy with the log–conformation
representation, are discussed.
The proposed algorithm utilizes a new streamfunction/log–conformation scheme. The drawbacks of the
classical velocity–pressure decoupled method, which is by far the most popular approach, are remedied with the
pure streamfunction formulation, which is derived from the pressureless vorticity‐based methods. The implicit
pure streamfunction formulation is formally more accurate than the velocity–pressure decoupled method,
because it is immune of decoupling errors. Moreover, the absence of decoupling enhances the stability of the
calculation. The governing equations (conservation laws and constitutive models) are discretized with the finite–
volume method, on a Cartesian grid. Discrete curl operators are applied to the discretized momentum equations
in order to obtain the matrix system of the discrete streamfunction variables. The coupling of the
streamfunction/log–conformation scheme with adaptive under‐relaxation and adaptive time‐stepping yield a
robust and efficient viscoelastic flow solver algorithm. The potential extension of the method to threedimensional
simulations is also discussed in this thesis.
Bi‐phasic/free‐surface flows are modelled with the Volume–of–Fluid (VOF) method, and the standard
piecewise–linear–interface–construction technique. In addition, a new Cellwise Conservative Unsplit (CCU)
advection scheme is presented. The CCU scheme updates the liquid volume fractions based on cellwise
backward‐tracking of the liquid volumes. The algorithm calculates non‐overlapping and conforming adjacent
donating regions, which ensures the boundedness and conservativeness of the liquid volume. As a result, the CCU
advection scheme is overall more accurate in classical benchmark tests, than the other state‐of‐the‐art multidimensional
VOF–advection schemes. In complex flows, the convergence rate of the CCU scheme with mesh
refinements is between 2 and 3. Moreover, the remaining geometrical errors are mostly due to the inability of
the standard piecewise linear interface to represent subgrid material topologies (i.e. high curvatures and thin
material filaments), rather than the proposed CCU advection scheme.
This thesis reports examples of numerical simulations of the Oldroyd–B liquid, calculated with the proposed
streamfunction/log–conformation/VOF–CCU methodology, implemented in Matlab. A thorough investigation of
the viscoelastic flow in the lid‐driven cavity is conducted. The streamfunction/log–conformation shows secondorder
accuracy and numerical stability at very large time‐step increments, which demonstrates the robustness of
vi
the scheme. The numerical results at moderate Weissenberg numbers are in good agreement with the literature.
Moreover, the enhancement of numerical stability, with the streamfunction/log–conformation scheme, makes it
possible to simulate elastic instabilities at high Weissenberg numbers. Quasi‐periodic elastic instabilities at the
upstream corner appear to be a mechanism that dissipates the stored elastic energy. The simulations of
viscoelastic flows in the planar 4:1 contraction are also in good agreement with data in the literature. Finally,
preliminary simulations of extrudate swelling show that the fracture melt extrusion defect could be caused by
instabilities in the stress layer at the surface of the die, triggered at moderate Weissenberg numbers.</div></div><div class="phddissertation"><table class="properties"><tbody><tr class="language"><th>Original language</th><td>English</td></tr></tbody></table><table class="properties"><tbody><tr><th>Place of Publication</th><td>Kgs. Lyngby</td></tr><tr><th>Publisher</th><td><a rel="Publisher" href="http://orbit.dtu.dk/en/publishers/technical-university-of-denmark-dtu(f7c040ab-194a-4da4-b458-670da24b2a08).html" class="link"><span>Technical University of Denmark (DTU)</span></a></td></tr><tr><th>Number of pages</th><td>234</td></tr><tr class="status"><th>State</th><td><span class="prefix">Published - </span><span class="date">2015</span></td></tr></tbody></table></div></div></div>Wed, 31 Dec 2014 23:00:00 GMThttp://orbit.dtu.dk/en/publications/numerical-simulation-of-viscoelastic-freesurface-flows-using-a-streamfunctionlogconformation-formulation-and-the-volumeoffluid-method(3c921ed6-6981-4ee6-9751-5d41dec05cbc).html2014-12-31T23:00:00ZInfluence of Maturation, Pathology and Functional Lateralization on 3D Sulcal Morphology using MRI
http://orbit.dtu.dk/en/publications/influence-of-maturation-pathology-and-functional-lateralization-on-3d-sulcal-morphology-using-mri(24fbc3ff-c0fa-416a-974d-d181328680f2).html
<div style='font-size: 9px;'><div class="rendering rendering_publication rendering_publication_short rendering_bookanthology rendering_short rendering_bookanthology_short"><h2 class="title"><a rel="BookAnthology" href="http://orbit.dtu.dk/en/publications/influence-of-maturation-pathology-and-functional-lateralization-on-3d-sulcal-morphology-using-mri(24fbc3ff-c0fa-416a-974d-d181328680f2).html" class="link"><span>Influence of Maturation, Pathology and Functional Lateralization on 3D Sulcal Morphology using MRI</span></a></h2><a rel="Person" href="http://orbit.dtu.dk/en/persons/betina-vase-jensen(5533ebc2-7873-43b2-a8ba-3291aade24c8).html" class="link person"><span>Jensen, B. V.</span></a> & <a rel="Person" href="http://orbit.dtu.dk/en/persons/rasmus-larsen(b3ea098f-fc7a-48a0-94ae-ae033577d7f1).html" class="link person"><span>Larsen, R.</span></a> <span class="date">2016</span> Kgs. Lyngby: <a rel="Publisher" href="http://orbit.dtu.dk/en/publishers/technical-university-of-denmark-dtu(f7c040ab-194a-4da4-b458-670da24b2a08).html" class="link"><span>Technical University of Denmark (DTU)</span></a>. <span class="numberofpages">137 p.</span> (DTU Compute PHD-2015; No. 398).<p class="type"><span class="type_family">Publication<span class="type_family_sep">: </span></span><span class="type_classification_parent">Research<span class="type_parent_sep"> › </span></span><span class="type_classification">Ph.D. thesis – Annual report year: 2016</span></p></div><div class="rendering rendering_publication rendering_publication_detailsportal rendering_bookanthology rendering_detailsportal rendering_bookanthology_detailsportal"><div class="abstract"><div class="textblock">The folding of the cortex results in a characteristic pattern of folds called sulci and ridges called gyri. The cortical folding varies greatly both within and between individuals. Despite a century of sustained research, the mechanisms underlying the observed variation in folding is still largely unknown. The shape of cortical sulci and gyri are determined in part by forces exerted by white matter fiber connections between various cortical regions. Studying the shape of the cortical sulci hence contributes to the understanding of the variation in the folding.<br /><br />This thesis concerns sulcal morphometry using Magnetic Resonance Imaging (MRI) and spatial statistical methods. The sulcal morphology has been studied with respect to: the normal development of a central sulcus; in relation to functional lateralization of the motor hand area in central sulcus and, finally, in relation to a pathological condition, anosmia, in the olfactory sulcus. This thesis describes and uses methods for sulci segmentation, sulci registration, sulci representation, and statistics for modeling sulci shape and testing sulcal morphology.<br /><br />This thesis describes methods to analyze sulcal morphology and show how sulci variability are influenced under normal development, by a functional ability, and by pathological conditions.</div></div><div class="phddissertation"><table class="properties"><tbody><tr class="language"><th>Original language</th><td>English</td></tr></tbody></table><table class="properties"><tbody><tr><th>Place of Publication</th><td>Kgs. Lyngby</td></tr><tr><th>Publisher</th><td><a rel="Publisher" href="http://orbit.dtu.dk/en/publishers/technical-university-of-denmark-dtu(f7c040ab-194a-4da4-b458-670da24b2a08).html" class="link"><span>Technical University of Denmark (DTU)</span></a></td></tr><tr><th>Number of pages</th><td>137</td></tr><tr class="status"><th>State</th><td><span class="prefix">Published - </span><span class="date">2016</span></td></tr></tbody></table></div> <table class="properties"><tbody><tr><th>Name</th><td>DTU Compute PHD-2015</td></tr><tr><th>Number</th><td>398</td></tr><tr><th>ISSN (print)</th><td>0909-3192</td></tr></tbody></table></div></div>Thu, 31 Dec 2015 23:00:00 GMThttp://orbit.dtu.dk/en/publications/influence-of-maturation-pathology-and-functional-lateralization-on-3d-sulcal-morphology-using-mri(24fbc3ff-c0fa-416a-974d-d181328680f2).html2015-12-31T23:00:00ZSystematic Methods and Tools for Computer Aided Modelling
http://orbit.dtu.dk/en/publications/systematic-methods-and-tools-for-computer-aided-modelling(a9f3ed89-1841-4b3f-9fc4-e5690542a682).html
<div style='font-size: 9px;'><div class="rendering rendering_publication rendering_publication_short rendering_bookanthology rendering_short rendering_bookanthology_short"><h2 class="title"><a rel="BookAnthology" href="http://orbit.dtu.dk/en/publications/systematic-methods-and-tools-for-computer-aided-modelling(a9f3ed89-1841-4b3f-9fc4-e5690542a682).html" class="link"><span>Systematic Methods and Tools for Computer Aided Modelling</span></a></h2><a rel="Person" href="http://orbit.dtu.dk/en/persons/marina-fedorova(f24cffde-ec11-47fd-ae46-320458692f1a).html" class="link person"><span>Fedorova, M.</span></a>, <a rel="Person" href="http://orbit.dtu.dk/en/persons/rafiqul-gani(bdf5e329-bb7b-4bf3-8fad-e4d087312c72).html" class="link person"><span>Gani, R.</span></a> & <a rel="Person" href="http://orbit.dtu.dk/en/persons/gurkan-sin(4c35984e-28c5-43c9-9a4b-c7ac589bf597).html" class="link person"><span>Sin, G.</span></a> <span class="date">2015</span> Kgs. Lyngby: <a rel="Publisher" href="http://orbit.dtu.dk/en/publishers/technical-university-of-denmark-dtu(f7c040ab-194a-4da4-b458-670da24b2a08).html" class="link"><span>Technical University of Denmark (DTU)</span></a>. <span class="numberofpages">150 p.</span><p class="type"><span class="type_family">Publication<span class="type_family_sep">: </span></span><span class="type_classification_parent">Research<span class="type_parent_sep"> › </span></span><span class="type_classification">Ph.D. thesis – Annual report year: 2015</span></p></div><div class="rendering rendering_publication rendering_publication_detailsportal rendering_bookanthology rendering_detailsportal rendering_bookanthology_detailsportal"><div class="abstract"><div class="textblock">Models are playing important roles in design and analysis of chemicals/bio-chemicals
based products and the processes that manufacture them. Model-based methods and
tools have the potential to decrease the number of experiments, which can be expensive
and time consuming, and point to candidates, where the experimental effort could be
focused.
<br />In this project a general modelling framework for systematic model building through
modelling templates, which supports the reuse of existing models via its new model
import and export capabilities, have been developed. The new feature for model transfer
has been developed by establishing a connection with an external modelling
environment for code generation.
<br />The main contribution of this thesis is a creation of modelling templates and their
connection with other modelling tools within a modelling framework. The goal was to
create a user-friendly system, which will make the model development process easier
and faster and provide the way for unified and consistent model documentation. The
modeller can use the template for their specific problem or to extend and/or adopt a
model. This is based on the idea of model reuse, which emphasizes the use of a model
not only for one specific application but also for future applications involving different
needs and levels of detail to match different purposes. As the result the model developer
can generate and test models systematically, efficiently and reliably. In this way,
development of products and processes can be faster, cheaper and very efficient.
<br />The developed modelling framework involves five main elements: 1) a modelling tool,
that includes algorithms for model generation; 2) a template library, which provides
building blocks for the templates (generic models previously developed); 3) computer
aided methods and tools, that include procedures to perform model translation, model
analysis, model verification/validation, model solution and model documentation; 4)
model transfer – export/import to/from other application for further extension and
application – several types of formats, such as XML-format and COM-objects, are
incorporated to allow the export and import of mathematical models; 5) a user interface
that provides the work-flow and data-flow to guide the user through the different
modelling tasks.</div></div><div class="phddissertation"><table class="properties"><tbody><tr class="language"><th>Original language</th><td>English</td></tr></tbody></table><table class="properties"><tbody><tr><th>Place of Publication</th><td>Kgs. Lyngby</td></tr><tr><th>Publisher</th><td><a rel="Publisher" href="http://orbit.dtu.dk/en/publishers/technical-university-of-denmark-dtu(f7c040ab-194a-4da4-b458-670da24b2a08).html" class="link"><span>Technical University of Denmark (DTU)</span></a></td></tr><tr><th>Number of pages</th><td>150</td></tr><tr class="status"><th>State</th><td><span class="prefix">Published - </span><span class="date">2015</span></td></tr></tbody></table></div></div></div>Wed, 31 Dec 2014 23:00:00 GMThttp://orbit.dtu.dk/en/publications/systematic-methods-and-tools-for-computer-aided-modelling(a9f3ed89-1841-4b3f-9fc4-e5690542a682).html2014-12-31T23:00:00ZGood towers of function Fields
http://orbit.dtu.dk/en/publications/good-towers-of-function-fields(111d272a-ba40-42d7-b567-9c261fddfba9).html
<div style='font-size: 9px;'><div class="rendering rendering_publication rendering_publication_short rendering_bookanthology rendering_short rendering_bookanthology_short"><h2 class="title"><a rel="BookAnthology" href="http://orbit.dtu.dk/en/publications/good-towers-of-function-fields(111d272a-ba40-42d7-b567-9c261fddfba9).html" class="link"><span>Good towers of function Fields</span></a></h2><a rel="Person" href="http://orbit.dtu.dk/en/persons/nhut-nguyen(886759cb-64af-4925-a64c-204194ba1b05).html" class="link person"><span>Nguyen, N.</span></a> & <a rel="Person" href="http://orbit.dtu.dk/en/persons/peter-beelen(da3e5b30-4aed-4f4f-9e17-3fda35fb6788).html" class="link person"><span>Beelen, P.</span></a> <span class="date">2015</span> Kgs. Lyngby: <a rel="Publisher" href="http://orbit.dtu.dk/en/publishers/technical-university-of-denmark-dtu(f7c040ab-194a-4da4-b458-670da24b2a08).html" class="link"><span>Technical University of Denmark (DTU)</span></a>. <span class="numberofpages">125 p.</span> (DTU Compute PHD-2015; No. 394).<p class="type"><span class="type_family">Publication<span class="type_family_sep">: </span></span><span class="type_classification_parent">Research<span class="type_parent_sep"> › </span></span><span class="type_classification">Ph.D. thesis – Annual report year: 2015</span></p></div><div class="rendering rendering_publication rendering_publication_detailsportal rendering_bookanthology rendering_detailsportal rendering_bookanthology_detailsportal"><div class="abstract"><div class="textblock">Algebraic curves are used in many different areas, including error-correcting codes. In such applications, it is important that the algebraic curve C meets some requirements. The curve must be defined over a finite field GF(q) with q elements, and then the curve also should have many points over this field. There are limits on how many points N(C) an algebraic curve C defined over a finite field can have.<br /><br />An invariant of the curve which is important in this context is the curve’s genus g(C). Hasse and Weil proved that N(C)≤q+1+2g(C) √q and this bound can in general not be improved. However if the genus is large compared with q, the bound can be improved. Drinfeld and Vladut showed the asymptotic result:<br /><br />A(q)≔limsup ( N(C)/ g(C)→∞ g(C)) ≤ √q-1.<br /><br />The quantity A(q) is called Ihara’s constant. If q is a square, it is known that A(q)=√q-1, while the value of the A(q) is unknown for all other values of q.<br /><br />In this thesis, we study a construction using Drinfeld modules that produces explicitly defined families of algebraic curves that asymptotically achieve Ihara’s constant. Such families of curves can also be described using towers of function fields. Restated in this language the aim of the project is to find good and optimal towers. Using the theory of Drinfeld modules and computer algebraic techniques, some new examples of good towers are obtained. We analyse towers of Drinfeld modular curves describing certain equivalence classes of rank 2 Drinfeld modules. Using rank 3 Drinfeld modules further examples of good towers are produced.<br /><br /></div></div><div class="phddissertation"><table class="properties"><tbody><tr class="language"><th>Original language</th><td>English</td></tr></tbody></table><table class="properties"><tbody><tr><th>Place of Publication</th><td>Kgs. Lyngby</td></tr><tr><th>Publisher</th><td><a rel="Publisher" href="http://orbit.dtu.dk/en/publishers/technical-university-of-denmark-dtu(f7c040ab-194a-4da4-b458-670da24b2a08).html" class="link"><span>Technical University of Denmark (DTU)</span></a></td></tr><tr><th>Number of pages</th><td>125</td></tr><tr class="status"><th>State</th><td><span class="prefix">Published - </span><span class="date">2015</span></td></tr></tbody></table></div> <table class="properties"><tbody><tr><th>Name</th><td>DTU Compute PHD-2015</td></tr><tr><th>Number</th><td>394</td></tr><tr><th>ISSN (print)</th><td>0909-3192</td></tr></tbody></table></div></div>Wed, 31 Dec 2014 23:00:00 GMThttp://orbit.dtu.dk/en/publications/good-towers-of-function-fields(111d272a-ba40-42d7-b567-9c261fddfba9).html2014-12-31T23:00:00ZImproved sea level determination in the Arctic regions through development of tolerant altimetry retracking
http://orbit.dtu.dk/en/publications/improved-sea-level-determination-in-the-arctic-regions-through-development-of-tolerant-altimetry-retracking(06686352-3777-4137-a661-22be8d7c2461).html
<div style='font-size: 9px;'><div class="rendering rendering_publication rendering_publication_short rendering_bookanthology rendering_short rendering_bookanthology_short"><h2 class="title"><a rel="BookAnthology" href="http://orbit.dtu.dk/en/publications/improved-sea-level-determination-in-the-arctic-regions-through-development-of-tolerant-altimetry-retracking(06686352-3777-4137-a661-22be8d7c2461).html" class="link"><span>Improved sea level determination in the Arctic regions through development of tolerant altimetry retracking</span></a></h2><a rel="Person" href="http://orbit.dtu.dk/en/persons/maulik-jain(701137d4-cc1d-4624-a276-4c228f5ac75a).html" class="link person"><span>Jain, M.</span></a>, <a rel="Person" href="http://orbit.dtu.dk/en/persons/ole-baltazar-andersen(c003fa87-9771-43b6-80c8-d9d2ddae6549).html" class="link person"><span>Andersen, O. B.</span></a> & <a rel="Person" href="http://orbit.dtu.dk/en/persons/joergen-dall(28e361c1-a38a-42f3-b72a-d4e1b153f7c2).html" class="link person"><span>Dall, J.</span></a> <span class="date">2015</span> Kgs. Lyngby: <a rel="Publisher" href="http://orbit.dtu.dk/en/publishers/technical-university-of-denmark-dtu(f7c040ab-194a-4da4-b458-670da24b2a08).html" class="link"><span>Technical University of Denmark (DTU)</span></a>. <span class="numberofpages">98 p.</span><p class="type"><span class="type_family">Publication<span class="type_family_sep">: </span></span><span class="type_classification_parent">Research<span class="type_parent_sep"> › </span></span><span class="type_classification">Ph.D. thesis – Annual report year: 2015</span></p></div><div class="rendering rendering_publication rendering_publication_detailsportal rendering_bookanthology rendering_detailsportal rendering_bookanthology_detailsportal"><div class="abstract"><div class="textblock">This PhD project involves the development of a suitable retracking strategy for processing ofCryosat-2 SAR (Synthetic Aperture Radar) altimetry waveforms in the Arctic Ocean. The Cryosat-2SAR altimetry waveforms are processed for precise and accurate SSH determination. Precise and accurate knowledge of SSH has various applications like gravity field determination, climate prediction, weather forecasting and studies of ocean currents and circulations.Cryosat-2 SAR altimetry waveforms in the Arctic can have a variety of shapes because of the superposition of the echoes from the water and the sea ice. Consequently, the waveforms are not well fitted with the existing physical retrackers and provide erroneous results with existing empirical retrackers like threshold retracker and OCOG (Offset Centre of Gravity) retracker.The research performed in this project is primarily divided in three segments. The first segment deals with the development of an improved and customized empirical retracker for the sea icecovered regions in the Arctic. The improved retrackers which are termed as primary peak empiricalretrackers work on just the primary peak of the waveform rather than the complete waveform. It is demonstrated through performance evaluation of the retracked SSHA, that the primary peak empirical retrackers demonstrate a more precise SSHA as compared to empirical retrackers like threshold retracker and OCOG retracker. Retracker performance evaluation is done for the primary peak threshold retracker, primary peak COG retracker, threshold retracker, OCOG retracker and the ESA retracker. For retracker performance evaluation, the standard deviation (STD) of the 1 HzSSHA is computed and a lower value of this STD indicates a more precisely retracked SSHA.The second segment deals with the customized application of physical retracking to Cryosat-2 SAR altimetry waveforms available in the Arctic Ocean. The SAMOSA3-C has been applied in the Arctic and is a combination of two modes – SAMOSA3-O mode and SAMOSA3-L Mode. The two modes deal with SSHA determination from the ocean type waveforms and the lead type waveforms. It is demonstrated that the SAMOSA3-C retracker exhibits a more precise SSHA as compared tothe primary peak retrackers and the ESA retracker. The accuracy evaluation of the retrackers showsthat the SAMOSA3-O retracker has the best accuracy when compared to tide gauge data in the Arctic. Combination of the physical and empirical retrackers is attempted in order to get the advantages of both the retrackers. The third segment deals with the combination of the physical (SAMOSA3-C)retracker and primary peak COG (empirical) retracker. It has the advantage of high precision fromthe SAMOSA3-C retracker. It also has the advantage of primary peak COG retracker with capability of estimating SSH in the sea ice areas where irregular type waveforms are present, which are neither lead type nor ocean type. Prior to combining the physical and empirical retracking, bias is removed and the primary peak COG retrackers SSHA values are corrected with the estimated bias. The removal of bias between the physical and empirical retrackers is a complex procedure. Various bias removal methods were tried and the best approach has been presented in this thesis.The combined physical empirical retracker results in a better precision than the primary peakretrackers and has a larger dataset of the estimated SSHA as compared to the SAMOSA3-Cretracker with inclusion of the SSHA in sea ice areas.</div></div><div class="phddissertation"><table class="properties"><tbody><tr class="language"><th>Original language</th><td>English</td></tr></tbody></table><table class="properties"><tbody><tr><th>Place of Publication</th><td>Kgs. Lyngby</td></tr><tr><th>Publisher</th><td><a rel="Publisher" href="http://orbit.dtu.dk/en/publishers/technical-university-of-denmark-dtu(f7c040ab-194a-4da4-b458-670da24b2a08).html" class="link"><span>Technical University of Denmark (DTU)</span></a></td></tr><tr><th>Number of pages</th><td>98</td></tr><tr class="status"><th>State</th><td><span class="prefix">Published - </span><span class="date">2015</span></td></tr></tbody></table></div><h3 class="subheader">Bibliographical note</h3><p>The thesis (incl. articles) is only accessible to researchers and students at DTU.</p></div></div>Wed, 31 Dec 2014 23:00:00 GMThttp://orbit.dtu.dk/en/publications/improved-sea-level-determination-in-the-arctic-regions-through-development-of-tolerant-altimetry-retracking(06686352-3777-4137-a661-22be8d7c2461).html2014-12-31T23:00:00ZRelaxed Simultaneous Tomographic Reconstruction and Segmentation with Class Priors for Poisson Noise
http://orbit.dtu.dk/en/publications/relaxed-simultaneous-tomographic-reconstruction-and-segmentation-with-class-priors-for-poisson-noise(e6e8a464-4b15-4d6c-a3d7-70ddfe11c30a).html
<div style='font-size: 9px;'><div class="rendering rendering_publication rendering_publication_short rendering_bookanthology rendering_short rendering_bookanthology_short"><h2 class="title"><a rel="BookAnthology" href="http://orbit.dtu.dk/en/publications/relaxed-simultaneous-tomographic-reconstruction-and-segmentation-with-class-priors-for-poisson-noise(e6e8a464-4b15-4d6c-a3d7-70ddfe11c30a).html" class="link"><span>Relaxed Simultaneous Tomographic Reconstruction and Segmentation with Class Priors for Poisson Noise</span></a></h2><a rel="Person" href="http://orbit.dtu.dk/en/persons/mikhail-romanov(07114b33-3e63-4083-b4f4-9ae207fcb324).html" class="link person"><span>Romanov, M.</span></a>, <a rel="Person" href="http://orbit.dtu.dk/en/persons/anders-bjorholm-dahl(c2bad3c8-b172-481b-bb99-d3c2bc4004ef).html" class="link person"><span>Dahl, A. B.</span></a>, <a rel="Person" href="http://orbit.dtu.dk/en/persons/yiqiu-dong(fbd1dafa-2d1c-4149-85b8-8998ea308e5f).html" class="link person"><span>Dong, Y.</span></a> & <a rel="Person" href="http://orbit.dtu.dk/en/persons/per-christian-hansen(6c6c6f32-e3b2-40d5-a407-aa8e2f051f7b).html" class="link person"><span>Hansen, P. C.</span></a> <span class="date">2015</span> Kgs. Lyngby: <a rel="Publisher" href="http://orbit.dtu.dk/en/publishers/technical-university-of-denmark-dtu(f7c040ab-194a-4da4-b458-670da24b2a08).html" class="link"><span>Technical University of Denmark (DTU)</span></a>. <span class="numberofpages">19 p.</span> (DTU Compute-Technical Report-2015; No. 6).<p class="type"><span class="type_family">Publication<span class="type_family_sep">: </span></span><span class="type_classification_parent">Research<span class="type_parent_sep"> › </span></span><span class="type_classification">Report – Annual report year: 2015</span></p></div><div class="rendering rendering_publication rendering_publication_detailsportal rendering_bookanthology rendering_detailsportal rendering_bookanthology_detailsportal"><div class="abstract"><div class="textblock">This work is a continuation of work on algorithms for simultaneous reconstruction and segmentation. In our previous work we developed an algorithm for data with Gaussian noise, and in that algorithm the coefficient matrix for the system is explicitly store. We improve this algorithm in two ways: our new algorithm can handle Poisson noise in the data, and it can solve much larger problems since it does not store the matrix. We formulate this algorithm and test it on artificial test problems. Our results show that the algorithm performs well, and that we are able to produce reconstructions and segmentations with small errors.</div></div><div class="scientificreport"><table class="properties"><tbody><tr class="language"><th>Original language</th><td>English</td></tr></tbody></table><table class="properties"><tbody><tr><th>Place of Publication</th><td>Kgs. Lyngby</td></tr><tr><th>Publisher</th><td><a rel="Publisher" href="http://orbit.dtu.dk/en/publishers/technical-university-of-denmark-dtu(f7c040ab-194a-4da4-b458-670da24b2a08).html" class="link"><span>Technical University of Denmark (DTU)</span></a></td></tr><tr><th>Number of pages</th><td>19</td></tr><tr class="status"><th>State</th><td><span class="prefix">Published - </span><span class="date">2015</span></td></tr></tbody></table></div> <table class="properties"><tbody><tr><th>Name</th><td>DTU Compute-Technical Report-2015</td></tr><tr><th>Number</th><td>6</td></tr><tr><th>ISSN (print)</th><td>1601-2321</td></tr></tbody></table></div></div>Wed, 31 Dec 2014 23:00:00 GMThttp://orbit.dtu.dk/en/publications/relaxed-simultaneous-tomographic-reconstruction-and-segmentation-with-class-priors-for-poisson-noise(e6e8a464-4b15-4d6c-a3d7-70ddfe11c30a).html2014-12-31T23:00:00Z