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作者： Hradil, Jiří Brno University of Technology

Cílem mé disertační práce je analyzovat a vyvinout parametrizační metodu pro 2D a 3D tvarové optimalizace v kontextu průmyslového aerodynamického návrhu letounu založen... 详细信息

Cílem mé disertační práce je analyzovat a vyvinout parametrizační metodu pro 2D a 3D tvarové optimalizace v kontextu průmyslového aerodynamického návrhu letounu založeném na CFD simulacích. Aerodynamická tvarová optimalizace je efektivní nástroj, který si klade za cíl snížení nákladů na návrh letounů. Nástroj založený na automatickém hledání optimálního tvaru. Klíčovou částí úspěšného optimalizačního procesu je použití vhodné parametrizační metody, metody schopné garantovat možnost dosažení optimálního tvaru. Parametrizační metody obecně používané v oblasti aerodynamické tvarové optimalizace momentálně nejsou připravený na komplikované průmyslové aplikace vyskytující se u moderních dopravních letounů, které mají šípová zalomená křídla s winglety a motorovými gondolami, přechodové prvky spojující např. trup s křídlem atd.. Existuje tedy potřeba nalezení obecné parametrizační metody, která bude aplikovatelná na širokou škálu různých geometrických tvarů. Free-Form Deformation (FFD[1]) parametrizace může, vzhledem ke svým schopnostem při zacházení s geometrií, být odpovědí na tuto potřebu. Adaptivní parametrizace by se měla být schopna automaticky přizpůsobit danému tvaru tak, aby byly její kontrolní body vhodně rozmístěny. Což umožní dostatečnou kontrolu deformací objektu, která zaručí možnost vytvoření optimálního tvaru objektu a splnění geometrických omezení. Primární aplikací takové parametrizační metody je deformace tvaru objektu. Dalším navrhovaným cílem je modifikace FFD parametrizační metody pro současné deformace tvaru objektu a CFD výpočetní sítě, umožnující velké deformace objektu při zachování kvality výpočetní sítě.

关键词： FFD adaptivní parametrizace deformace sítě adjoint CFD nestrukturované sítě FFD adaptive parameterization mesh deformation adjoint CFD unstructured meshes Text

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An adaptively scaled frequency-domain parameterization for history matching

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JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING 2011年第3-4期75卷 289-303页

作者： Bhark, Eric Jafarpour, Behnam Datta-Gupta, Akhil Texas A&M Univ Dept Petr Engn College Stn TX 77843 USA

History matching problems are typically underdetermined and are at once confronted with the problems of solution non-uniqueness, instability, and the ability to both reproduce field observations and provide a reliable forecast. We address these challenges with a new adaptive multiscale history matching formulation that parameterizes the reservoir properties in the frequency domain. The geologic model updating is carried out by successively increasing the level of detail up to a spatial scale sufficient to match the observed data. Our method begins by constructing a coarse representation of the field using the lowest-frequency components of its discrete cosine parameterization. This substantially reduces the number of unknown parameters to be resolved during history matching, leading to a better posed inverse problem. A gradient-based minimization is then performed to match the production data. Next, the updated model is incrementally refined in the frequency domain and the minimization is repeated until the data misfit is reduced below a pre-specified criterion or until no further improvements are observed. During minimization, components of the gradient insensitive to production information are removed by a truncated singular value decomposition (TSVD), facilitating iterative convergence and providing additional regularization. In this manner a balance is achieved between parameter reduction which is required for stability, and the spatial resolution of heterogeneity required for reproduction of the production history. The low-frequency approximation of the permeability field helps to honor geologic continuity and is particularly suited for resolving the large-scale heterogeneity that has a dominant influence on the field-scale flow regime and production response. Applications of the approach are demonstrated using the SPE10 and PUNQ-S3 models and involve waterflood history matching with water-cut and bottom-hole pressure data. Our results show that the principle g

关键词： adaptive parameterization discrete cosine transform multiscale inversion subsurface characterization history matching

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Wells' identification and transmissivity estimation in porous media

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INVERSE PROBLEMS IN SCIENCE AND ENGINEERING 2020年第7期28卷 906-929页

作者： Ben Ameur, Hend Hariga-Tlatli, Nejla Mansouri, Wafa Univ El Manar LAMSIN ENIT Tunis Tunisia Univ Carthage IPEST Carthage Tunis Tunisia Univ Carthage INAT Carthage Tunis Tunisia

This paper deals with the inverse problems of wells' location and transmissivity estimation in a saturated porous media. Wells are considered as circular holes and the heterogeneous domain is divided into zones with constant transmissivity in each one. The main used tool for wells' location is the topological gradient method applied to a design function defined with respect to available data. Moreover, this technique is incorporated in an adaptive parameterization algorithm leading, in a progressive way, to recover interfaces between hydrogeological zones and transmissivity values. The obtained algorithm allows to recover jointly the transmissivities and the wells' locations. Then the proposed method is tested on a simplified model inspired from the Rocky Mountain aquifer.

关键词： Inverse problem topological gradient adaptive parameterization Wells' location transmissivity identification

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Image segmentation with multidimensional refinement indicators

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INVERSE PROBLEMS IN SCIENCE AND ENGINEERING 2011年第5期19卷 577-597页

作者： Ben Ameur, H. Chavent, G. Clement, F. Weis, P. INRIA Paris Rocquencourt EPI Estime F-78153 Le Chesnay France Univ Tunis FSB Tunis 1002 Tunisia Univ Tunis ENIT LAMSIN Tunis 1002 Tunisia

We transpose an optimal control technique to the image segmentation problem. The idea is to consider image segmentation as a parameter estimation problem. The parameter to estimate is the colour of the pixels of the image. We use the adaptive parameterization technique which builds iteratively an optimal representation of the parameter into uniform regions that form a partition of the domain, hence corresponding to a segmentation of the image. We minimize an error function during the iterations, and the partition of the image into regions is optimally driven by the gradient of this error. The resulting segmentation algorithm inherits desirable properties from its optimal control origin: soundness, robustness and flexibility.

关键词： image segmentation adaptive parameterization inverse problem optimal control

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Dynamic optimization of the load change of a large-scale chemical plant by adaptive single shooting

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COMPUTERS & CHEMICAL ENGINEERING 2010年第11期34卷 1873-1889页

作者： Hartwich, Arndt Marquardt, Wolfgang Rhein Westfal TH Aachen AVT Proc Syst Engn D-52064 Aachen Germany

Dynamic optimization allows for the determination of the upper bound of achievable performance in the operation of continuous chemical processes in transient operation which often results from load or grade changes. Performance assessment can rely on the computation of optimal trajectories for selected scenarios which properly reflect the operational envelope. Realistic industrial problems, however, involve very large-scale dynamic process models and consequently require highly-efficient and robust optimization algorithms. In this work we demonstrate the feasibility of operability assessment by means of dynamic optimization in an industrial case study involving a large-scale process model comprising about 12,000 differential-algebraic model equations. The numerical strategy employed relies on a single shooting method combined with adaptive control grid refinement to minimize the complexity of the numerical problem to the extent possible. This algorithm proves to be the key to success and saves about 95% of computational complexity in comparison to a conventional equidistant discretization. (C) 2010 Elsevier Ltd. All rights reserved.

关键词： Optimal control Switchability Operability Single shooting Control vector parameterization Grid adaptation adaptive parameterization Chemical plant Distillation Reactor Recycle Turnpike effect

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First-order indicators for the estimation of discrete fractures in porous media

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INVERSE PROBLEMS IN SCIENCE AND ENGINEERING 2018年第1期26卷 1-32页

作者： Ameur, H. Ben Chavent, G. Cheikh, F. Clement, F. Martin, V. Roberts, J. E. Univ Tunis LAMSIN ENIT Tunis Tunisia Ctr Rech Inria Paris Paris France UTC LMAC Compiegne France

Faults and geological barriers can drastically affect the flow patterns in porous media. Such fractures can be modelled as interfaces that interact with the surrounding matrix. We propose a new technique for the estimation of the location and hydrogeological properties of a small number of large fractures in a porous medium from given distributed pressure or flow data. At each iteration, the algorithm builds a short list of candidates by comparing fracture indicators. These indicators quantify at the first order the decrease of a data misfit function;they are cheap to compute. Then, the best candidate is picked up by minimization of the objective function for each candidate. Optimally driven by the fit to the data, the approach has the great advantage of not requiring remeshing, nor shape derivation. The stability of the algorithm is shown on a series of numerical examples representative of typical situations.

关键词： adaptive parameterization inverse problem flow in porous media fractured porous media fault and barrier

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adaptive multiscale permeability estimation

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COMPUTATIONAL GEOSCIENCES 2003年第1期7卷 1-25页

作者： Grimstad, AA Mannseth, T Nævdal, G Urkedal, H RF Rogaland Res N-5008 Bergen Norway

With multiscale permeability estimation one does not select parameterization prior to the estimation. Instead, one performs a hierarchical search for the right parameterization while solving a sequence of estimation problems with an increasing parameterization dimension. In some previous works on the subject, the same refinement is applied all over the porous medium. This may lead to over-parameterization, and subsequently, to unrealistic permeability estimates and excessive computational work. With adaptive multiscale permeability estimation, the new parameterization at an arbitrary stage in the estimation sequence is such that new degrees of freedom are not necessarily introduced all over the porous medium. The aim is to introduce new degrees of freedom only where it is warranted by the data. In this paper, we introduce a novel adaptive multiscale estimation. The approach is used to estimate absolute permeability from two-phase pressure data in several numerical examples.

关键词： adaptive parameterization inverse problem porous medium regularization

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Modification of the method of multicriteria image processing for preprocessing thermal imaging images with adaptive change in filtering parameters based on neural network approaches

Modification of the method of multicriteria image processing...

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Conference on Multimodal Image Exploitation and Learning

作者： Semenishchev, Evgeny Agaian, Sos Zelensky, Aleksandr Surkov, Evgenii Khamidullin, Ilia Voronin, Viacheslav Tula State Univ Tu1SU 92 Sq Lenina Tula 300012 Tula Region Russia CUNY Dept Comp Sci New York NY 10314 USA Moscow State Tech Univ STANKIN 1a Vadkovsky Moscow 127055 Russia

ISBN: (纸本)9781510650770;9781510650763

The article presents a noise reduction method based on minimizing a multicriteria objective function. The technique makes it possible to perform minimization according to the criteria of the root-mean-square difference of the deviation between adjacent estimates of pixel values (vertical, horizontal) and between the mean-square difference of the input elements and the resulting estimates. The first criterion allows you to reduce the noise component in locally stationary areas of the image, the second to preserve the boundaries of transitions between objects. In the article, the adaptation of the choice of the processing parameter is performed using a trained neural network. The training was carried out on standard test images from widely used databases (Kodak, MS COCO, etc.). Tables comparing the effectiveness of the proposed adaptation algorithm to the previously applied approach are given.

关键词： denoising image adaptive parameterization image filtering

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Real-time characterization of non-metallic inclusions by optical scanning and milling of steel samples

Real-time characterization of non-metallic inclusions by opt...

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Conference on Optical Micro- and Nanometrology IV

作者： Herwig, Johannes Buck, Christoph Thurau, Matthias Pauli, Josef Luther, Wolfram Univ Duisburg Essen D-47048 Duisburg Germany

ISBN: (纸本)9780819491220

The cleanliness of steel is described by the amount, size, composition, morphology, and distribution of nonmetallic inclusions (NMIs). These nonmetals are present because of natural physical-chemical effects, and because during continuous casting steel is accidentally contaminated with slag, refractories, and materials from casting moulds. NMIs influence the properties of steel. Therefore, in this paper, a combined milling and image processing system is proposed that mills and scans slices of steel samples to retrieve volumetric information about NMIs. The system is capable of scanning steel samples of 300 x 100 x 90mm(3) in size at spatial resolutions of either 3, 5, 10, or 20 mu m and a volumetric resolution of 10 mu m within a few hours. After each milling operation the steel surface is captured by a moving large-area CCD image sensor. The optical system further consists of a distortion-free macro lens and diffuse coaxial lighting for brightfield illumination. Additional results using dome lighting are also presented. The interaction of an NMI with the milling cutter results in non-homogeneous NMI reflectances which carry information about the NMI's mass density and chemical compound. Although the steel surface is highly reflective, the milling cutter creates a periodic pattern of moldings which is accentuated by patterns of shadow and light. An adaptive wedge filter in the Fourier space dampens those artifacts. NMIs are binarized separately in every image by local thresholding. In order to reduce segmentation artifacts neighboring slices in the volumetric stack of images are filtered using morphological operators. A statistical analysis of the segmentation results estimates the macro cleanliness. Furthermore an interactive 3D visualization enables the exploration of NMIs and their distribution within the sample. Different viewing, filtering and sorting capabilities are implemented, like ordering NMIs with regard to their shape factor. It is expected that the stu

关键词： Anomaly detection adaptive parameterization texture analysis interactive visualization

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adaptive whole Earth tomography

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GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS 2003年第3期4卷

作者： Sambridge, M Faletic, R Australian Natl Univ Res Sch Earth Sci Canberra ACT 0200 Australia Australian Natl Univ Dept Phys Fac Sci Canberra ACT 0200 Australia

[1] An approach for seismic tomography is presented which allows the parameterization to be refined during the inversion. The objective is to use the data to refine the mesh and the velocity model together, and hence both are considered part of the solution. Some simple rules are used to identify the volumes of a three-dimensional model in need of refinement. The self-adaptive parameterization is applied to an initial mesh built from uniformly distributed spherical triangles and Delaunay tetrahedra. Application of the technique to a typical summary ray P-wave arrival time data set shows it to be both feasible and practical for large scale whole Earth tomography. A noticeable trend in the resulting models, as the parameterization is refined, is the thinning of the Farallon and Tethys subduction features imaged in the mid mantle, together with an increase in amplitude of the velocity perturbation.

关键词： seismic tomography adaptive parameterization numerical techniques tectonophysics : evolution of the Earth : tomography mathematical geophysics : inverse theory mathematical geophysics : numerical solutions seismology : lithosphere and upper mantle

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