999 resultados para Algebraic multigrid method


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Kokonaisvaltaisen laatujohtamisen malli TQM (Total Quality Management) on noussut yhdeksi merkittävimmistä konsepteista globaalissa liiketoiminnassa, missä laatu on tärkeä kilpailutekijä. Tämä diplomityö pureutuu nykyaikaiseen kokonaisvaltaisen laatujohtamisen konseptiin, joka nostaa perinteisen laatuajattelun uudelle tasolle. Moderni laatujohtamisajattelu on kasvanut koskemaan yrityksen toiminnan kaikkia osa-alueita. Työn tavoitteena on TietoEnator Käsittely ja Verkkopalvelut liiketoiminta-alueen osalta laadun sekä liiketoiminnallisen suorituskyvyn parantaminen kokonaisvaltaisesti. Ennen varsinaisen laatujohtamis-konseptin käsittelyä työ esittelee ensin yleisellä tasolla perinteistä laatu käsitettä sekä käsittelee lyhyestiICT-liiketoimintaa ja siihen liittyviä standardeja. Lopuksi tutkimus esittelee priorisoituja parannusehdotuksia ja askeleita jotka auttavat organisaatiota saavuttamaan kokonaisvaltaisen laatujohtamiskonseptin mukaisia pyrkimyksiä.

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The main goal of this paper is to propose a convergent finite volume method for a reactionâeuro"diffusion system with cross-diffusion. First, we sketch an existence proof for a class of cross-diffusion systems. Then the standard two-point finite volume fluxes are used in combination with a nonlinear positivity-preserving approximation of the cross-diffusion coefficients. Existence and uniqueness of the approximate solution are addressed, and it is also shown that the scheme converges to the corresponding weak solution for the studied model. Furthermore, we provide a stability analysis to study pattern-formation phenomena, and we perform two-dimensional numerical examples which exhibit formation of nonuniform spatial patterns. From the simulations it is also found that experimental rates of convergence are slightly below second order. The convergence proof uses two ingredients of interest for various applications, namely the discrete Sobolev embedding inequalities with general boundary conditions and a space-time $L^1$ compactness argument that mimics the compactness lemma due to Kruzhkov. The proofs of these results are given in the Appendix.

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Työssä tutkittiin muovattujen kartonkivuokien sekä muovattujen kartonkinäytteiden rinnastettavuutta. Puristusvaiheen prosessiolosuhteiden miellettiin vaikuttavan eniten multidimensionaliseen muodonmuutokseen. Multidimensionaalista muodonmuutosta simuloitiin uudella muovaamiseen soveltuvalla muovauslaitteella. Kirjallisuusosassa keskeisiä teemoja ovat kartongin muovaus sekä kuitupohjaisen materiaalin reologinen käyttäytyminen. Kirjallisuusosassa esitellään lisäksi yksi tekninen sovellus, jonka avulla kyetään ennustamaan kuitumateriaalin muovautuvuutta sekä mittaamaan tapahtunutta muodonmuutosta. Prosessiparametrien teoreettista vaikutustakuituihin tarkastellaan myös kirjallisuusosassa. Kokeellisessa osassa toteutettiin kartonkivuokien valmistus puristamalla. Vastaavilla prosessiparametreilla muovattiin myös pienemmät testinäytteet. Perinteiset yksidimensionaliset deformaatiomittaukset toteutettiin lujuusominaisuuksien laboratoriomäärityksinä. Myös kitka, joka toimii tärkeänä muuttujana prässäysprosessissa, mitattiin laboratorio-olosuhteissa. Tämän työn tulokset osoittavat uuden kehitetyn muovausmenetelmän toimivuuden. Asema-voima kuvaajat ovat selkeitä sekä helposti luettavia. Tuloksissa havaittiin materiaalin muovauspotentiaalin sekä asema-voima kuvaajan välillä vallitseva yhteys. Erittäin merkittävä huomio oli myös, että muovipäällystetyllä kartongilla oli yhteys päällystämättömän kartongin asema-voima kuvaajaan. Tämä tulos osoittaa, että muovipäällystetyn kartongin muovautuvuutta voi olla mahdollista ennustaa pohjakartongin muovautuvuustulosten perusteella. Perinteiset yksidimensionaliset laboratoriomittaukset eivät kykene antamaan riittävää informaatiota muovautuvuuden ennustamiseen. Tästä näkökulmasta on tärkeää että kartongin multidimensionalista muotoutuvuutta voidaankin tutkia kehitetyllä muovausmenetelmällä.

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Knowledge of the pathological diagnosis before deciding the best strategy for treating parasellar lesions is of prime importance, due to the relative high morbidity and side-effects of open direct approaches to this region, known to be rich in important vasculo-nervous structures. When imaging is not evocative enough to ascertain an accurate pathological diagnosis, a percutaneous biopsy through the transjugal-transoval route (of Hartel) may be performed to guide the therapeutic decision.The chapter is based on the authors' experience in 50 patients who underwent the procedure over the ten past years. There was no mortality and only little (mostly transient) morbidity. Pathological diagnosis accuracy of the method revealed good, with a sensitivity of 0.83 and a specificity of 1.In the chapter the authors first recall the surgical anatomy background from personal laboratory dissections. They then describe the technical procedure, as well as the tissue harvesting method. Finally they define indications together with the decision-making process.Due to the constraint trajectory of the biopsy needle inserted through the Foramen Ovale, accessible lesions are only those located in the Meckel trigeminal Cave, the posterior sector of the cavernous sinus compartment, and the upper part of the petroclival region.The authors advise to perform this percutaneous biopsy method when imaging does not provide sufficient evidence of the pathological nature of the lesion, for therapeutic decision. Goal is to avoid unnecessary open surgery or radiosurgery, also inappropriate chemo-/radio-therapy.

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Personal results are presented to illustrate the development of immunoscintigraphy for the detection of cancer over the last 12 years, from the early experimental results in nude mice grafted with human colon carcinoma to the most modern form of immunoscintigraphy applied to patients, using I123 labeled Fab fragments from monoclonal anti-CEA antibodies detected by single photon emission computerized tomography (SPECT). The first generation of immunoscintigraphy used I131 labeled, immunoadsorbent purified, polyclonal anti-CEA antibodies and planar scintigraphy, as the detection system. The second generation used I131 labeled monoclonal anti-CEA antibodies and SPECT, while the third generation employed I123 labeled fragments of monoclonal antibodies and SPECT. The improvement in the precision of tumor images with the most recent forms of immunoscintigraphy is obvious. However, we think the usefulness of immunoscintigraphy for routine cancer management has not yet been entirely demonstrated. Further prospective trials are still necessary to determine the precise clinical role of immunoscintigraphy. A case report is presented on a patient with two liver metastases from a sigmoid carcinoma, who received through the hepatic artery a therapeutic dose (100 mCi) of I131 coupled to 40 mg of a mixture of two high affinity anti-CEA monoclonal antibodies. Excellent localisation in the metastases of the I131 labeled antibodies was demonstrated by SPECT and the treatment was well tolerated. The irradiation dose to the tumor, however, was too low at 4300 rads (with 1075 rads to the normal liver and 88 rads to the bone marrow), and no evidence of tumor regression was obtained. Different approaches for increasing the irradiation dose delivered to the tumor by the antibodies are considered.

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A recently developed calculation method to determine stoichiometric dissociation constants of weak acids from potentiometric titration data is described. The titration data from three different weak acids in aqueous salt solutions at 25 °C were used as examples of the use of the method. The salt alone determined the ionic strength of the solutions considered in this study, and salt molalities up to 0,5 mol kg -1 were used.

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Résumé : Cette thèse de doctorat est le fruit d'un projet de recherche européen financé par le quatrième programme cadre de la Commission Européenne (DG XII, Standards, Measurement and Testing). Ce projet, dénommé SMT-CT98-2277, a été financé pour la partie suisse par l'Office Fédéral de l'Education et de la Science (OFES, Berne, Suisse). Le but de ce projet était de développer une méthode harmonisée et collaborativement testée pour le profilage des impuretés de l'amphétamine illicite par chromatographie capillaire en phase gazeuse. Le travail a été divisé en sept phases majeures qui concernaient la synthèse de l'amphétamine, l'identification d'impuretés, l'optimisation de la préparation de l'échantillon et du système chromatographique, la variabilité des résultats, l'investigation de méthodes mathématiques pour la classification et la comparaison de profils et finalement l'application de la méthode à des réels échantillons illicites. La méthode résultant de ce travail n'a pas seulement montré que les données étaient interchangeables entre laboratoires mais aussi qu'elle était supérieure en de nombreux points aux méthodes préalablement publiées dans la littérature scientifique. Abstract : This Ph.D. thesis was carried out in parallel to an European project funded by the fourth framework program of the European Commission (DG XII, Standards, Measurement and Testing). This project, named SMT-CT98-2277 was funded, for the Swiss part, by the Federal Office of Education and Science (OFES, Bern, Switzerland). The aim of the project was to develop a harmonised, collaboratively tested method for the impurity profiling of illicit amphetamine by capillary gas chromatography. The work was divided into seven main tasks which deal with the synthesis of amphetamine, identification of impurities, optimization of sample preparation and of the chromatographic system, variability of the results, investigation of numerical methods for the classification and comparison of profiles and finally application of the methodology to real illicit samples. The resulting method has not only shown to produce interchangeable data between different laboratories but was also found to be superior in many aspects to previously published methods.

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Koneet voidaan usein jakaa osajärjestelmiin, joita ovat ohjaus- ja säätöjärjestelmät, voimaa tuottavat toimilaitteet ja voiman välittävät mekanismit. Eri osajärjestelmiä on simuloitu tietokoneavusteisesti jo usean vuosikymmenen ajan. Osajärjestelmien yhdistäminen on kuitenkin uudempi ilmiö. Usein esimerkiksi mekanismien mallinnuksessa toimilaitteen tuottama voimaon kuvattu vakiona, tai ajan funktiona muuttuvana voimana. Vastaavasti toimilaitteiden analysoinnissa mekanismin toimilaitteeseen välittämä kuormitus on kuvattu vakiovoimana, tai ajan funktiona työkiertoa kuvaavana kuormituksena. Kun osajärjestelmät on erotettu toisistaan, on niiden välistenvuorovaikutuksien tarkastelu erittäin epätarkkaa. Samoin osajärjestelmän vaikutuksen huomioiminen koko järjestelmän käyttäytymissä on hankalaa. Mekanismien dynamiikan mallinnukseen on kehitetty erityisesti tietokoneille soveltuvia numeerisia mallinnusmenetelmiä. Useimmat menetelmistä perustuvat Lagrangen menetelmään, joka mahdollistaa vapaasti valittaviin koordinaattimuuttujiin perustuvan mallinnuksen. Numeerista ratkaisun mahdollistamiseksi menetelmän avulla muodostettua differentiaali-algebraaliyhtälöryhmää joudutaan muokkaamaan esim. derivoimalla rajoiteyhtälöitä kahteen kertaan. Menetelmän alkuperäisessä numeerisissa ratkaisuissa kaikki mekanismia kuvaavat yleistetyt koordinaatit integroidaan jokaisella aika-askeleella. Tästä perusmenetelmästä johdetuissa menetelmissä riippumattomat yleistetyt koordinaatit joko integroidaan ja riippuvat koordinaatit ratkaistaan rajoiteyhtälöiden perusteella tai yhtälöryhmän kokoa pienennetään esim. käyttämällä nopeus- ja kiihtyvyysanalyyseissä eri kiertymäkoordinaatteja kuin asema-analyysissä. Useimmat integrointimenetelmät on alun perin tarkoitettu differentiaaliyhtälöiden (ODE) ratkaisuunjolloin yhtälöryhmään liitetyt niveliä kuvaavat algebraaliset rajoiteyhtälöt saattavat aiheuttaa ongelmia. Nivelrajoitteiden virheiden korjaus, stabilointi, on erittäin tärkeää mekanismien dynamiikan simuloinnin onnistumisen ja tulosten oikeellisuuden kannalta. Mallinnusmenetelmien johtamisessa käytetyn virtuaalisen työn periaatteen oletuksena nimittäin on, etteivät rajoitevoimat tee työtä, eli rajoitteiden vastaista siirtymää ei tapahdu. Varsinkaan monimutkaisten järjestelmien pidemmissä analyyseissä nivelrajoitteet eivät toteudu tarkasti. Tällöin järjestelmän energiatasapainoei toteudu ja järjestelmään muodostuu virtuaalista energiaa, joka rikkoo virtuaalisen työn periaatetta, Tästä syystä tulokset eivät enää pidäpaikkaansa. Tässä raportissa tarkastellaan erityyppisiä mallinnus- ja ratkaisumenetelmiä, ja vertaillaan niiden toimivuutta yksinkertaisten mekanismien numeerisessa ratkaisussa. Menetelmien toimivuutta tarkastellaan ratkaisun tehokkuuden, nivelrajoitteiden toteutumisen ja energiatasapainon säilymisen kannalta.

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This paper analyzes the possibilities of integrating cost information and engineering design. Special emphasis is on finding the potential of using the activity-based costing (ABC) method when formulating cost information for the needs of design engineers. This paper suggests that ABC is more useful than the traditional job order costing, but the negative issue is the fact that ABC models become easily too complicated, i.e. expensive to build and maintain, and difficult to use. For engineering design the most suitable elements of ABC are recognizing activities of the company, constructing acitivity chains, identifying resources, activity and cost drivers, as wellas calculating accurate product costs. ABC systems including numerous cost drivers can become complex. Therefore, a comprehensive ABC based cost information system for the use of design engineers should be considered criticaly. Combining the suitable ideas of ABC with engineering oriented thinking could give competentresults.

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The changing business environment demands that chemical industrial processes be designed such that they enable the attainment of multi-objective requirements and the enhancement of innovativedesign activities. The requirements and key issues for conceptual process synthesis have changed and are no longer those of conventional process design; there is an increased emphasis on innovative research to develop new concepts, novel techniques and processes. A central issue, how to enhance the creativity of the design process, requires further research into methodologies. The thesis presentsa conflict-based methodology for conceptual process synthesis. The motivation of the work is to support decision-making in design and synthesis and to enhance the creativity of design activities. It deals with the multi-objective requirements and combinatorially complex nature of process synthesis. The work is carriedout based on a new concept and design paradigm adapted from Theory of InventiveProblem Solving methodology (TRIZ). TRIZ is claimed to be a `systematic creativity' framework thanks to its knowledge based and evolutionary-directed nature. The conflict concept, when applied to process synthesis, throws new lights on design problems and activities. The conflict model is proposed as a way of describing design problems and handling design information. The design tasks are represented as groups of conflicts and conflict table is built as the design tool. The general design paradigm is formulated to handle conflicts in both the early and detailed design stages. The methodology developed reflects the conflict nature of process design and synthesis. The method is implemented and verified through case studies of distillation system design, reactor/separator network design and waste minimization. Handling the various levels of conflicts evolve possible design alternatives in a systematic procedure which consists of establishing an efficient and compact solution space for the detailed design stage. The approach also provides the information to bridge the gap between the application of qualitative knowledge in the early stage and quantitative techniques in the detailed design stage. Enhancement of creativity is realized through the better understanding of the design problems gained from the conflict concept and in the improvement in engineering design practice via the systematic nature of the approach.

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La hiérarchie de Wagner constitue à ce jour la plus fine classification des langages ω-réguliers. Par ailleurs, l'approche algébrique de la théorie de langages formels montre que ces ensembles ω-réguliers correspondent précisément aux langages reconnaissables par des ω-semigroupes finis pointés. Ce travail s'inscrit dans ce contexte en fournissant une description complète de la contrepartie algébrique de la hiérarchie de Wagner, et ce par le biais de la théorie descriptive des jeux de Wadge. Plus précisément, nous montrons d'abord que le degré de Wagner d'un langage ω-régulier est effectivement un invariant syntaxique. Nous définissons ensuite une relation de réduction entre ω-semigroupes pointés par le biais d'un jeu infini de type Wadge. La collection de ces structures algébriques ordonnée par cette relation apparaît alors comme étant isomorphe à la hiérarchie de Wagner, soit un quasi bon ordre décidable de largeur 2 et de hauteur ω. Nous exposons par la suite une procédure de décidabilité de cette hiérarchie algébrique : on décrit une représentation graphique des ω-semigroupes finis pointés, puis un algorithme sur ces structures graphiques qui calcule le degré de Wagner de n'importe quel élément. Ainsi le degré de Wagner de tout langage ω-régulier peut être calculé de manière effective directement sur son image syntaxique. Nous montrons ensuite comment construire directement et inductivement une structure de n''importe quel degré. Nous terminons par une description détaillée des invariants algébriques qui caractérisent tous les degrés de cette hiérarchie. Abstract The Wagner hierarchy is known so far to be the most refined topological classification of ω-rational languages. Also, the algebraic study of formal languages shows that these ω-rational sets correspond precisely to the languages recognizable by finite pointed ω-semigroups. Within this framework, we provide a construction of the algebraic counterpart of the Wagner hierarchy. We adopt a hierarchical game approach, by translating the Wadge theory from the ω-rational language to the ω-semigroup context. More precisely, we first show that the Wagner degree is indeed a syntactic invariant. We then define a reduction relation on finite pointed ω-semigroups by means of a Wadge-like infinite two-player game. The collection of these algebraic structures ordered by this reduction is then proven to be isomorphic to the Wagner hierarchy, namely a well-founded and decidable partial ordering of width 2 and height $\omega^\omega$. We also describe a decidability procedure of this hierarchy: we introduce a graph representation of finite pointed ω-semigroups allowing to compute their precise Wagner degrees. The Wagner degree of every ω-rational language can therefore be computed directly on its syntactic image. We then show how to build a finite pointed ω-semigroup of any given Wagner degree. We finally describe the algebraic invariants characterizing every Wagner degree of this hierarchy.

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Convective transport, both pure and combined with diffusion and reaction, can be observed in a wide range of physical and industrial applications, such as heat and mass transfer, crystal growth or biomechanics. The numerical approximation of this class of problemscan present substantial difficulties clue to regions of high gradients (steep fronts) of the solution, where generation of spurious oscillations or smearing should be precluded. This work is devoted to the development of an efficient numerical technique to deal with pure linear convection and convection-dominated problems in the frame-work of convection-diffusion-reaction systems. The particle transport method, developed in this study, is based on using rneshless numerical particles which carry out the solution along the characteristics defining the convective transport. The resolution of steep fronts of the solution is controlled by a special spacial adaptivity procedure. The serni-Lagrangian particle transport method uses an Eulerian fixed grid to represent the solution. In the case of convection-diffusion-reaction problems, the method is combined with diffusion and reaction solvers within an operator splitting approach. To transfer the solution from the particle set onto the grid, a fast monotone projection technique is designed. Our numerical results confirm that the method has a spacial accuracy of the second order and can be faster than typical grid-based methods of the same order; for pure linear convection problems the method demonstrates optimal linear complexity. The method works on structured and unstructured meshes, demonstrating a high-resolution property in the regions of steep fronts of the solution. Moreover, the particle transport method can be successfully used for the numerical simulation of the real-life problems in, for example, chemical engineering.

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Requirements-relatedissues have been found the third most important risk factor in software projects and as the biggest reason for software project failures. This is not a surprise since; requirements engineering (RE) practices have been reported deficient inmore than 75% of all; enterprises. A problem analysis on small and low maturitysoftware organizations revealed two; central reasons for not starting process improvement efforts: lack of resources and uncertainty; about process improvementeffort paybacks.; In the constructive part of the study a basic RE method, BaRE, was developed to provide an; easy to adopt way to introduce basic systematic RE practices in small and low maturity; organizations. Based on diffusion of innovations literature, thirteen desirable characteristics; were identified for the solution and the method was implemented in five key components:; requirements document template, requirements development practices, requirements; management practices, tool support for requirements management, and training.; The empirical evaluation of the BaRE method was conducted in three industrial case studies. In; this evaluation, two companies established a completely new RE infrastructure following the; suggested practices while the third company conducted continued requirements document; template development based on the provided template and used it extensively in practice. The; real benefits of the adoption of the method were visible in the companies in four to six months; from the start of the evaluation project, and the two small companies in the project completed; their improvement efforts with an input equal to about one person month. The collected dataon; the case studies indicates that the companies implemented new practices with little adaptations; and little effort. Thus it can be concluded that the constructed BaRE method is indeed easy to; adopt and it can help introduce basic systematic RE practices in small organizations.

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Fatigue life assessment of weldedstructures is commonly based on the nominal stress method, but more flexible and accurate methods have been introduced. In general, the assessment accuracy is improved as more localized information about the weld is incorporated. The structural hot spot stress method includes the influence of macro geometric effects and structural discontinuities on the design stress but excludes the local features of the weld. In this thesis, the limitations of the structural hot spot stress method are discussed and a modified structural stress method with improved accuracy is developed and verified for selected welded details. The fatigue life of structures in the as-welded state consists mainly of crack growth from pre-existing cracks or defects. Crack growth rate depends on crack geometry and the stress state on the crack face plane. This means that the stress level and shape of the stress distribution in the assumed crack path governs thetotal fatigue life. In many structural details the stress distribution is similar and adequate fatigue life estimates can be obtained just by adjusting the stress level based on a single stress value, i.e., the structural hot spot stress. There are, however, cases for which the structural stress approach is less appropriate because the stress distribution differs significantly from the more common cases. Plate edge attachments and plates on elastic foundations are some examples of structures with this type of stress distribution. The importance of fillet weld size and weld load variation on the stress distribution is another central topic in this thesis. Structural hot spot stress determination is generally based on a procedure that involves extrapolation of plate surface stresses. Other possibilities for determining the structural hot spot stress is to extrapolate stresses through the thickness at the weld toe or to use Dong's method which includes through-thickness extrapolation at some distance from the weld toe. Both of these latter methods are less sensitive to the FE mesh used. Structural stress based on surface extrapolation is sensitive to the extrapolation points selected and to the FE mesh used near these points. Rules for proper meshing, however, are well defined and not difficult to apply. To improve the accuracy of the traditional structural hot spot stress, a multi-linear stress distribution is introduced. The magnitude of the weld toe stress after linearization is dependent on the weld size, weld load and plate thickness. Simple equations have been derived by comparing assessment results based on the local linear stress distribution and LEFM based calculations. The proposed method is called the modified structural stress method (MSHS) since the structural hot spot stress (SHS) value is corrected using information on weld size andweld load. The correction procedure is verified using fatigue test results found in the literature. Also, a test case was conducted comparing the proposed method with other local fatigue assessment methods.