Disc Filter External Models in an Integrated Simulation Environment

Työssä tutkittiin kiekkosuodattimeen liittyviä ulkoisia simulointimalleja integroidussa simulointiympäristössä. Työn tarkoituksena oli parantaa olemassa olevaa mekanistista kiekkosuodatinmallia. Malli laadittiin dynaamiseen paperiteollisuuden tarpeisiin tehtyyn simulaattoriin (APMS), jossa olevaan alkuperäiseen mekanistiseen malliin tehtiin ulkoinen lisämalli, joka käyttää hyväkseen kiekkosuodatinvalmistajan mittaustuloksia. Laitetiedon saatavuutta suodattimien käyttäjille parannettiin luomalla Internetissä sijaitsevalle palvelimelle kiekkosuodattimen laitetietomäärittelyt. Suodatinvalmistaja voi palvella asiakkaitaan viemällä laitetiedot palvelimelle ja yhdistämällä laitetiedon simulointimalliin. Tämä on mahdollista Internetin ylitse käytettävän integroidun simulointiympäristön avulla, jonka on tarkoitus kokonaisvaltaisesti yhdistää simulointi ja prosessisuunnittelu. Suunnittelijalle tarjotaan työkalut, joilla dynaaminen simulointi, tasesimulointi ja kaavioiden piirtäminen onnistuu prosessilaitetiedon ollessa saatavilla. Nämä työkalut on tarkoitus toteuttaa projektissa nimeltä Galleria, jossa luodaan prosessimalli- ja laitetietopalvelin Internetiin. Gallerian käyttöliittymän avulla prosessisuunnittelija voi käyttää erilaisia simulointiohjelmistoja ja niihin luotuja valmiita malleja, sekä saada käsiinsä ajan tasalla olevaa laitetietoa. Ulkoinen kiekkosuodatinmalli laskee suodosvirtaamat ja suodosten pitoisuudet likaiselle, kirkkaalle ja superkirkkaalle suodokselle. Mallin syöttöparametrit ovat kiekkojen pyörimisnopeus, sisään tulevan syötön pitoisuus, suotautuvuus (freeness) ja säätöparametri, jolla säädetään likaisen ja kirkkaan suodoksen keskinäinen suhde. Suotautuvuus kertoo mistä massasta on kyse. Mitä suurempi suotautuvuus on, sitä paremmin massa suodattuu ja sitä puhtaampia suodokset yleensä ovat. Mallin parametrit viritettiin regressioanalyysillä ja valmistajan palautetta apuna käyttäen. Käyttäjä voi valita haluaako hän käyttää ulkoista vai alkuperäistä mallia. Alkuperäinen malli täytyy ensin alustaa antamalla sille nominaaliset toimintapisteet virtaamille ja pitoisuuksille tietyllä pyörimisnopeudella. Ulkoisen mallin yhtälöitä voi käyttää alkuperäisen mallin alustamiseen, jos alkuperäinen malli toimii ulkoista paremmin. Ulkoista mallia voi käyttää myös ilman simulointiohjelmaa Galleria-palvelimelta käsin. Käyttäjälle avautuu näin mahdollisuus tarkastella kiekkosuodattimien parametreja ja nähdä suotautumistulokset oman työasemansa ääreltä mistä tahansa, kunhan Internetyhteys on olemassa. Työn tuloksena kiekkosuodattimien laitetiedon saatavuus käyttäjille parani ja alkuperäisen simulointimallin rajoituksia ja puutteita vähennettiin.

Simulation Supported Robot Programming using XML

The main objective of this master's thesis is to study robot programming using simulation software, and also how to embed the simulation software into company's own robot controlling software. The further goal is to study a new communication interface to the assembly line's components -more precisely how to connect the robot cell into this new communication system. Conveyor lines are already available where the conveyors use the new communication standard. The robot cell is not yet capable of communicating with to other devices using the new communication protocols. The main problem among robot manufacturers is that they all have their own communication systems and programming languages. There has not been any common programming language to program all the different robot manufacturers robots, until the RRS (Realistic Robot Simulation) standards were developed. The RRS - II makes it possible to create the robot programs in the simulation software and it gives a common user interface for different robot manufacturers robots. This thesis will present the RRS - II standard and the robot manufacturers situation for the RRS - II support. Thesis presents how the simulation software can be embedded into company's own robot controlling software and also how the robot cell can be connected to the CAMX (Computer Aided Manufacturing using XML) communication system.

Analysis of flow dynamics in right ventricular outflow tract.

BACKGROUND: The mechanism behind early graft failure after right ventricular outflow tract (RVOT) reconstruction is not fully understood. Our aim was to establish a three-dimensional computational fluid dynamics (CFD) model of RVOT to investigate the hemodynamic conditions that may trigger the development of intimal hyperplasia and arteriosclerosis. METHODS: Pressure, flow, and diameter at the RVOT, pulmonary artery (PA), bifurcation of the PA, and left and right PAs were measured in 10 normal pigs with a mean weight of 24.8 ± 0.78 kg. Data obtained from the experimental scenario were used for CFD simulation of pressure, flow, and shear stress profile from the RVOT to the left and right PAs. RESULTS: Using experimental data, a CFD model was obtained for 2.0 and 2.5-L/min pulsatile inflow profiles. In both velocity profiles, time and space averaged in the low-shear stress profile range from 0-6.0 Pa at the pulmonary trunk, its bifurcation, and at the openings of both PAs. These low-shear stress areas were accompanied to high-pressure regions 14.0-20.0 mm Hg (1866.2-2666 Pa). Flow analysis revealed a turbulent flow at the PA bifurcation and ostia of both PAs. CONCLUSIONS: Identified local low-shear stress, high pressure, and turbulent flow correspond to a well-defined trigger pattern for the development of intimal hyperplasia and arteriosclerosis. As such, this real-time three-dimensional CFD model may in the future serve as a tool for the planning of RVOT reconstruction, its analysis, and prediction of outcome.

ADVANCED NUMERICAL METHODS FOR SIMULATING MICROBUBBLE IN AN AERATED MIXING TANK

Fluid mixing in mechanically agitated tanks is one of the major unit operations in many industries. Bubbly flows have been of interest among researchers in physics, medicine, chemistry and technology over the centuries. The aim of this thesis is to use advanced numerical methods for simulating microbubble in an aerated mixing tank. Main components of the mixing tank are a cylindrical vessel, a rotating Rushton turbine and the air nozzle. The objective of Computational Fluid Dynamics (CFD) is to predict fluid flow, heat transfer, mass transfer and chemical reactions. The CFD simulations of a turbulent bubbly flow are carried out in a cylindrical mixing tank using large eddy simulation (LES) and volume of fluid (VOF) method. The Rushton turbine induced flow is modeled by using a sliding mesh method. Numerical results are used to describe the bubbly flows in highly complex liquid flow. Some of the experimental works related to turbulent bubbly flow in a mixing tank are briefly reported. Numerical simulations are needed to complete and interpret the results of the experimental work. Information given by numerical simulations has a major role in designing and scaling-up mixing tanks. The results of this work have been reported in the following scientific articles: ·Honkanen M., Koohestany A., Hatunen T., Saarenrinne P., Zamankhan P., Large eddy simulations and PIV experiments of a two-phase air-water mixer, in Proceedings of ASME Fluids Engineering Summer Conference (2005). ·Honkanen M., Koohestany A., Hatunen T., Saarenrinne P., Zamankhan P., Dynamical States of Bubbling in an Aerated Stirring Tank, submitted to J. Computational Physics.

CFD study of penetration and mixing of fuel in a circulating fluidized bed furnace

The aim of this thesis is to study the mixing of fuel and, also to some extent, the mixing of air in a circulating fluidized bed boiler. In the literature survey part of this thesis, a review is made of the previous experimental studies related to the fuel and air mixing in the circulating fluidized beds. In the simulation part of it the commercial computational fluid dynamics software (FLUENT) is used with the Eulerian multiphase model for studying the fuel mixing in the two and three-dimensional furnace geometries. The results of the three-dimensional simulations are promising and, therefore suggestions are made for the future simulations. The two-dimensional studies give new information of the effects of the fluidization velocity, fuel particle size and fuel density on the fuel mixing. However, the present results show that three-dimensional models produce more realistic representation of the circulating fluidized bed behavior.

Virtauslaskentaa ja energia-analyysiä hyödyntävä huoneilman lämpöolosuhteiden simulointimalli

Huonetilojen lämpöolosuhteiden hallinta on tärkeä osa talotekniikan suunnittelua. Tavallisesti huonetilan lämpöolosuhteita mallinnetaan menetelmillä, joissa lämpödynamiikkaa lasketaan huoneilmassa yhdessä laskentapisteessä ja rakenteissa seinäkohtaisesti. Tarkastelun kohteena on yleensä vain huoneilman lämpötila. Tämän diplomityön tavoitteena oli kehittää huoneilman lämpöolosuhteiden simulointimalli, jossa rakenteiden lämpödynamiikka lasketaan epästationaarisesti energia-analyysilaskennalla ja huoneilman virtauskenttä mallinnetaan valittuna ajanhetkenä stationaarisesti virtauslaskennalla. Tällöin virtauskentälle saadaan jakaumat suunnittelun kannalta olennaisista suureista, joita tyypillisesti ovat esimerkiksi ilman lämpötila ja nopeus. Simulointimallin laskentatuloksia verrattiin testihuonetiloissa tehtyihin mittauksiin. Tulokset osoittautuivat riittävän tarkoiksi talotekniikan suunnitteluun. Mallilla simuloitiin kaksi huonetilaa, joissa tarvittiin tavallista tarkempaa mallinnusta. Vertailulaskelmia tehtiin eri turbulenssimalleilla, diskretointitarkkuuksilla ja hilatiheyksillä. Simulointitulosten havainnollistamiseksi suunniteltiin asiakastuloste, jossa on esitetty suunnittelun kannalta olennaiset asiat. Simulointimallilla saatiin lisätietoa varsinkin lämpötilakerrostumista, joita tyypillisesti on arvioitu kokemukseen perustuen. Simulointimallin kehityksen taustana käsiteltiin rakennusten sisäilmastoa, lämpöolosuhteita ja laskentamenetelmiä sekä mallinnukseen soveltuvia kaupallisia ohjelmia. Simulointimallilla saadaan entistä tarkempaa ja yksityiskohtaisempaa tietoa lämpöolosuhteiden hallinnan suunnitteluun. Mallin käytön ongelmia ovat vielä virtauslaskennan suuri laskenta-aika, turbulenssin mallinnus, tuloilmalaitteiden reunaehtojen tarkka määritys ja laskennan konvergointi. Kehitetty simulointimalli tarjoaa hyvän perustan virtauslaskenta- ja energia-analyysiohjelmien kehittämiseksi ja yhdistämiseksi käyttäjäystävälliseksi talotekniikan suunnittelutyökaluksi.

Performance Analysis of Two Quantum Reaction Dynamics Codes: Time-Dependent and Time-Independent Strategies

The computer simulation of reaction dynamics has nowadays reached a remarkable degree of accuracy. Triatomic elementary reactions are rigorously studied with great detail on a straightforward basis using a considerable variety of Quantum Dynamics computational tools available to the scientific community. In our contribution we compare the performance of two quantum scattering codes in the computation of reaction cross sections of a triatomic benchmark reaction such as the gas phase reaction Ne + H2+ %12. NeH++ H. The computational codes are selected as representative of time-dependent (Real Wave Packet [ ]) and time-independent (ABC [ ]) methodologies. The main conclusion to be drawn from our study is that both strategies are, to a great extent, not competing but rather complementary. While time-dependent calculations advantages with respect to the energy range that can be covered in a single simulation, time-independent approaches offer much more detailed information from each single energy calculation. Further details such as the calculation of reactivity at very low collision energies or the computational effort related to account for the Coriolis couplings are analyzed in this paper.

USER'S GUIDE FOR ADVANCED PROCESS SIMULATION SOFTWARE APROS 5

Tässä diplomityössä tehtiin käyttäjän opas kehittyneelle prosessisimulointiohjelmistolle APROS 5. Opas on osa VTT Energialle tehtävää APROS 5 käyttäjän koulutuspakettia, joka julkaistaan myöhemmin CD-ROM -muotoisena. Prosessisimulointiohjelmistoa AAPROS 5 voidaan käyttää termohydraulisten prosessien, automaatiopiirien ja sähköjärjestelmien mallinnuksessa. Ohjelma sisältää myös neutroniikkamallin ydinreaktorin käyttäytymisen mallintamiseksi. APROS:in aikaisemmilla UNIX-ympäristössä toimivilla versioilla on toteutettu useita ydinvoimalaitosten turvallisuustutkimukseen liittyviä analyysejä ja sekä ydinvoimalaitosten että konventionaalisten voimalaitosten koulutussimulaattoreita. APROS 5 toimii Windows NT -ympäristössä ja on oleellisesti erilainen käyttää kuin aikaisemmat versiot. Tämän myötä syntyi tarve uudelle käyttäjän oppaalle. Käyttäjän oppaassa esitetään APROS 5:n tärkeimmät toiminnot, mallinnuksen periaatteet ja termohydraulisten ja neutroniikan ratkaisumallit. Lisäksi oppaassa esitetään esimerkki, jossa mallinnetaan yksinkertaistettu VVER-440 -tyyppisen ydinvoimalaitoksen primääripiiri. Yksityiskohtaisempaa tietoa ohjelmistosta on saatavilla APROS 5 -dokumentaatiosta.

Development of the Simulation Environment for the Mobile Phone User Interfaces

Diplomityössä käsitellään Nokia Mobile Phonesin matkapuhelimien käyttöliittymäohjelmistojen suunnittelu-ja testausympäristön kehitystä. Ympäristöön lisättiin kaksi ohjelmistomodulia avustamaan simulointia ja versionhallintaa. Visualisointityökalulla matkapuhelimen toiminta voidaan jäljittää suunnittelu- kaavioihin tilasiirtyminä, kun taas vertailusovelluksella kaavioiden väliset erot nähdään graafisesti. Kehitetyt sovellukset parantavat käyttöliittymien suunnitteluprosessia tehostaen virheiden etsintää, optimointia ja versionhallintaa. Visualisointityökalun edut ovat merkittävät, koska käyttöliittymäsovellusten toiminta on havaittavissa suunnittelu- kaavioista reaaliaikaisen simuloinnin yhteydessä. Näin virheet ovat välittömästi paikannettavissa. Lisäksi työkalua voidaan hyödyntää kaavioita optimoitaessa, jolloin sovellusten kokoja muistintarve pienenee. Graafinen vertailutyökalu tuo edun rinnakkaiseen ohjelmistosuunnitteluun. Eri versioisten suunnittelukaavioiden erot ovat nähtävissä suoraan kaaviosta manuaalisen vertailun sijaan. Molemmat työkalut otettiin onnistuneesti käyttöön NMP:llä vuoden 2001 alussa.

Disentangling the formation of contrasting tree line physiognomies combining model selection and Bayesian parameterization for simulation models.

Alpine tree-line ecotones are characterized by marked changes at small spatial scales that may result in a variety of physiognomies. A set of alternative individual-based models was tested with data from four contrasting Pinus uncinata ecotones in the central Spanish Pyrenees to reveal the minimal subset of processes required for tree-line formation. A Bayesian approach combined with Markov chain Monte Carlo methods was employed to obtain the posterior distribution of model parameters, allowing the use of model selection procedures. The main features of real tree lines emerged only in models considering nonlinear responses in individual rates of growth or mortality with respect to the altitudinal gradient. Variation in tree-line physiognomy reflected mainly changes in the relative importance of these nonlinear responses, while other processes, such as dispersal limitation and facilitation, played a secondary role. Different nonlinear responses also determined the presence or absence of krummholz, in agreement with recent findings highlighting a different response of diffuse and abrupt or krummholz tree lines to climate change. The method presented here can be widely applied in individual-based simulation models and will turn model selection and evaluation in this type of models into a more transparent, effective, and efficient exercise.

INCLUDING RISK IN ECONOMIC FEASIBILITY ANALYSIS:A STOCHASTIC SIMULATION MODEL FOR BLUEBERRY INVESTMENT DECISIONS IN CHILE

ABSTRACT The traditional method of net present value (NPV) to analyze the economic profitability of an investment (based on a deterministic approach) does not adequately represent the implicit risk associated with different but correlated input variables. Using a stochastic simulation approach for evaluating the profitability of blueberry (Vaccinium corymbosum L.) production in Chile, the objective of this study is to illustrate the complexity of including risk in economic feasibility analysis when the project is subject to several but correlated risks. The results of the simulation analysis suggest that the non-inclusion of the intratemporal correlation between input variables underestimate the risk associated with investment decisions. The methodological contribution of this study illustrates the complexity of the interrelationships between uncertain variables and their impact on the convenience of carrying out this type of business in Chile. The steps for the analysis of economic viability were: First, adjusted probability distributions for stochastic input variables (SIV) were simulated and validated. Second, the random values of SIV were used to calculate random values of variables such as production, revenues, costs, depreciation, taxes and net cash flows. Third, the complete stochastic model was simulated with 10,000 iterations using random values for SIV. This result gave information to estimate the probability distributions of the stochastic output variables (SOV) such as the net present value, internal rate of return, value at risk, average cost of production, contribution margin and return on capital. Fourth, the complete stochastic model simulation results were used to analyze alternative scenarios and provide the results to decision makers in the form of probabilities, probability distributions, and for the SOV probabilistic forecasts. The main conclusion shown that this project is a profitable alternative investment in fruit trees in Chile.

Computational toolbox towards evolutionary domain mapping of membrane proteins

Membrane proteins account for about 20% to 30% of all proteins encoded in a typical genome. They play central roles in multiple cellular processes mediating the interaction of the cell with its surrounding. Over 60% of all drug targets contain a membrane domain. The experimental difficulties of obtaining a crystal structural severely limits our ability or understanding of membrane protein function. Computational evolutionary studies of proteins are crucial for the prediction of 3D structures. In this project, we construct a tool able to quantify the evolutionary positive selective pressure on each residue of membrane proteins through maximum likelihood phylogeny reconstruction. The conservation plot combined with a structural homology model is also a potent tool to predict those residues that have essentials roles in the structure and function of a membrane protein and can be very useful in the design of validation experiments.

Advances in MRI-based computational neuroanatomy: from morphometry to in-vivo histology.

PURPOSE OF REVIEW: Current computational neuroanatomy based on MRI focuses on morphological measures of the brain. We present recent methodological developments in quantitative MRI (qMRI) that provide standardized measures of the brain, which go beyond morphology. We show how biophysical modelling of qMRI data can provide quantitative histological measures of brain tissue, leading to the emerging field of in-vivo histology using MRI (hMRI). RECENT FINDINGS: qMRI has greatly improved the sensitivity and specificity of computational neuroanatomy studies. qMRI metrics can also be used as direct indicators of the mechanisms driving observed morphological findings. For hMRI, biophysical models of the MRI signal are being developed to directly access histological information such as cortical myelination, axonal diameters or axonal g-ratio in white matter. Emerging results indicate promising prospects for the combined study of brain microstructure and function. SUMMARY: Non-invasive brain tissue characterization using qMRI or hMRI has significant implications for both research and clinics. Both approaches improve comparability across sites and time points, facilitating multicentre/longitudinal studies and standardized diagnostics. hMRI is expected to shed new light on the relationship between brain microstructure, function and behaviour, both in health and disease, and become an indispensable addition to computational neuroanatomy.

Value at Risk in measuring market risk: Historical simulation

In this study the theoretical part was created to make comparison between different Value at Risk models. Based on that comparison one model was chosen to the empirical part which concentrated to find out whether the model is accurate to measure market risk. The purpose of this study was to test if Volatility-weighted Historical Simulation is accurate in measuring market risk and what improvements does it bring to market risk measurement compared to traditional Historical Simulation. Volatility-weighted method by Hull and White (1998) was chosen In order to improve the traditional methods capability to measure market risk. In this study we found out that result based on Historical Simulation are dependent on chosen time period, confidence level and how samples are weighted. The findings of this study are that we cannot say that the chosen method is fully reliable in measuring market risk because back testing results are changing during the time period of this study.

Fluid dynamics simulation of right ventricular outflow tract oversizing.

OBJECTIVES: Repair of the right ventricular outflow tract (RVOT) in paediatric cardiac surgery remains challenging due to the high reoperation rate. Intimal hyperplasia and consequent arteriosclerosis is one of the most important limitation factors for graft durability. Since local shear stress and pressure are predictive elements for intimal hyperplasia and wall degeneration, we sought to determine in an oversized 12-mm RVOT model, with computed fluid dynamics simulation, the local haemodynamical factors that may explain intimal hyperplasia. This was done with the aim of identifying the optimal degree of oversizing for a 12-mm native RVOT. METHODS: Twenty domestic pigs, with a weight of 24.6 ± 0.89 kg and a native RVOT diameter of 12 ± 1.7 mm, had valve conduits of 12, 16, 18 and 20 mm implanted. Pressure and flow were measured at 75, 100 and 125% of normal flow at RVOT at the pulmonary artery, pulmonary artery bifurcation and at the left and right pulmonary arteries. Three-dimensional computed fluid dynamics (CFD) simulation in all four geometries in all flow modalities was performed. Local shear stress and pressure conditions were investigated. RESULTS: Corresponding to 75, 100 and 125% of steady-state flow, three inlet velocity profiles were obtained, 0.2, 0.29 and 0.36 m/s, respectively. At inflow velocity profiles, low shear stress areas, ranged from 0 to 2 Pa, combined with high-pressure areas ranging from 11.5 to 12.1 mmHg that were found at distal anastomosis, at bifurcation and at the ostia of the left and right pulmonary arteries in all geometries. CONCLUSIONS: In all three oversized geometries, the local reparation of shear stress and pressure in the 16-mm model showed a similar local profile as in the native 12 mm RVOT. According to these findings, we suggest oversizing the natural 12-mm RVOT by not more than 4 mm. The elements responsible for wall degeneration and intimal hyperplasia remain very similar to the conditions present in native RVOT.