Dieselmoottorin esisuunnittelun kehittäminen simuloimalla

Diplomityö tehtiin Wärtsilä Finland Oy:n toimeksiannosta. Työ kohdistui yrityksen suunnittelemien keskinopeudella pyörivien nelitahti dieselmoottoreiden esisuunnittelun kehittämiseen. Esisuunnittelun osuus koko tuotesuunnittelussa on merkittävä, minkä vuoksi esisuunnitteluprosessin tehostaminen vaikuttaa koko tuotesuunnitteluprosessiin ja sen lopputuloksiin. Tällä hetkellä esisuunnitteluprosessi on jakautunut useaan eri vaiheeseen ja eri tiimeille, mikä aiheuttaa ongelmia esisuunnittelun läpiviemisessä. Työn tavoitteena oli tutkia nykyaikaisen kaupallisen simulointiohjelmiston soveltuvuutta kohdeyrityksessä esisuunnitteluprosessin eri vaiheiden yhdistämiseen. Työssä selvitettiin esisuunnittelun alussa käytettäviä suunnitteluparametreja, ja niiden hyödyntämistä suunniteltaessa simulointimallia kaupalliseen ohjelmistoon. Vaatimuksena oli, että ohjelmiston on toimittava parametreilla, jotka jo nyt ovat yrityksessä käytössä. Lisäksi simulointimallin antamat tulokset oli oltava hyödynnettävissä yksiselitteisesti yrityksen myöhemmissä tuotesuunnitteluvaiheissa. Myös mallin luomiseen tarvittavien parametrien määrä tuli pitää mahdollisimman pienenä. Esisuunnittelumallin toteuttamisessa tutkittiin kaupallisen AVL Excite Designer - ohjelmiston soveltuvuutta. Ohjelmisto ei soveltunut täysin tuottamaan halutun muotoisia tuloksia annetuilla parametreilla. Ohjelmiston muokkaaminen vaatimuksia vastaavaksi osoittautui työmäärältään suureksi. Yhtenä ratkaisuna olisi kaupallisen ohjelmiston käyttämisen sijaan suunnitella kyseiseen ongelmaan paremmin soveltuva oma ohjelmisto, jolloin toimivuus ja pitkän tähtäimen käyttövarmuus paranisi.

Potentials of process intensification in the Finnish petrochemical industry

This research was motivated by the need to examine the potential application areas of process intensification technologies in Neste Oil Oyj. According to the company’s interest membrane reactor technology was chosen and applicability of this technology in refining industry was investigated. Moreover, Neste Oil suggested a project which is related to the CO2 capture from FCC unit flue gas stream. The flowrate of the flue gas is 180t/h and consist of approximately 14% by volume CO2. Membrane based absorption process (membrane contactor) was chosen as a potential technique to model CO2 capture from fluid catalytic cracking (FCC) unit effluent. In the design of membrane contactor, a mathematical model was developed to describe CO2 absorption from a gas mixture using monoethanole amine (MEA) aqueous solution. According to the results of literature survey, in the hollow fiber contactor for laminar flow conditions approximately 99 % percent of CO2 can be removed by using a 20 cm in length polyvinylidene fluoride (PDVF) membrane. Furthermore, the design of whole process was performed by using PRO/II simulation software and the CO2 removal efficiency of the whole process obtained as 97 %. The technical and economical comparisons among existing MEA absorption processes were performed to determine the advantages and disadvantages of membrane contactor technology.

Models and applications for risk assessment and prediction of Asian soybean rust epidemics

Asian rust of soybean [Glycine max (L.) Merril] is one of the most important fungal diseases of this crop worldwide. The recent introduction of Phakopsora pachyrhizi Syd. & P. Syd in the Americas represents a major threat to soybean production in the main growing regions, and significant losses have already been reported. P. pachyrhizi is extremely aggressive under favorable weather conditions, causing rapid plant defoliation. Epidemiological studies, under both controlled and natural environmental conditions, have been done for several decades with the aim of elucidating factors that affect the disease cycle as a basis for disease modeling. The recent spread of Asian soybean rust to major production regions in the world has promoted new development, testing and application of mathematical models to assess the risk and predict the disease. These efforts have included the integration of new data, epidemiological knowledge, statistical methods, and advances in computer simulation to develop models and systems with different spatial and temporal scales, objectives and audience. In this review, we present a comprehensive discussion on the models and systems that have been tested to predict and assess the risk of Asian soybean rust. Limitations, uncertainties and challenges for modelers are also discussed.

Improving the calculation of rate of stratification in APROS

APROS (Advanced Process Simulation Environment) is a computer simulation program developed to simulate thermal hydraulic processes in nuclear and conventional power plants. Earlier research at VTT Technological Research Centre of Finland had found the current version of APROS to produce inaccurate simulation results for a certain case of loop seal clearing. The objective of this Master’s thesis is to find and implement an alternative method for calculating the rate of stratification in APROS, which was found to be the reason for the inaccuracies. Brief literature study was performed and a promising candidate for the new method was found. The new method was implemented into APROS and tested against experiments and simulations from two test facilities and the current version of APROS. Simulation results with the new version were partially conflicting; in some cases the new method was more accurate than the current version, in some the current method was better. Overall, the new method can be assessed as an improvement.

The Use of Radiostereometric Analysis in Fractures of the Distal Radius: From Phantom Models to Clinical Application

Radiostereometric analysis (RSA) is a highly accurate method for the measurement of in vivo micromotion of orthopaedic implants. Validation of the RSA method is a prerequisite for performing clinical RSA studies. Only a limited number of studies have utilised the RSA method in the evaluation of migration and inducible micromotion during fracture healing. Volar plate fixation of distal radial fractures has increased in popularity. There is still very little prospective randomised evidence supporting the use of these implants over other treatments. The aim of this study was to investigate the precision, accuracy, and feasibility of using RSA in the evaluation of healing in distal radius fractures treated with a volar fixed-angle plate. A physical phantom model was used to validate the RSA method for simple distal radius fractures. A computer simulation model was then used to validate the RSA method for more complex interfragmentary motion in intra-articular fractures. A separate pre-clinical investigation was performed in order to evaluate the possibility of using novel resorbable markers for RSA. Based on the validation studies, a prospective RSA cohort study of fifteen patients with plated AO type-C distal radius fractures with a 1-year follow-up was performed. RSA was shown to be highly accurate and precise in the measurement of fracture micromotion using both physical and computer simulated models of distal radius fractures. Resorbable RSA markers demonstrated potential for use in RSA. The RSA method was found to have a high clinical precision. The fractures underwent significant translational and rotational migration during the first two weeks after surgery, but not thereafter. Maximal grip caused significant translational and rotational interfragmentary micromotion. This inducible micromotion was detectable up to eighteen weeks, even after the achievement of radiographic union. The application of RSA in the measurement of fracture fragment migration and inducible interfragmentary micromotion in AO type-C distal radius fractures is feasible but technically demanding. RSA may be a unique tool in defining the progress of fracture union.

The development and evaluation of a distance learning system in ophthalmology

INTRODUCTION: Web-based e-learning is a teaching tool increasingly used in many medical schools and specialist fields, including ophthalmology. AIMS: this pilot study aimed to develop internet-based course-based clinical cases and to evaluate the effectiveness of this method within a graduate medical education group. METHODS: this was an interventional randomized study. First, a website was built using a distance learning platform. Sixteen first-year ophthalmology residents were then divided into two randomized groups: one experimental group, which was submitted to the intervention (use of the e-learning site) and another control group, which was not submitted to the intervention. The students answered a printed clinical case and their scores were compared. RESULTS: there was no statistically significant difference between the groups. CONCLUSION: We were able to successfully develop the e-learning site and the respective clinical cases. Despite the fact that there was no statistically significant difference between the access and the non access group, the study was a pioneer in our department, since a clinical case online program had never previously been developed.

Dynamical and structural properties of dendrimer macromolecules

This work is devoted to the study of the dynamical and structural properties of dendrimers. Different approaches were used: analytical theory, computer simulation results and experimental NMR studies. The theory of the relaxation spectrum of dendrimer macromolecules was developed. Relaxation processes which are manifest in the local orientational mobility of dendrimer macromolecules were established and studied in detail. Theoretical results and conclusions were used for experimental studies of carbosilane dendimers.

Luistonestojärjestelmän ja elektronisen tasauspyörästön testaus ja implementointi hybridityökoneympäristöön

Työssä toteutettiin C-kielellä luistonestojärjestelmä ja elektroninen tasauspyörästö Simulinkmallien pohjalta hybridityökoneeseen. Hybridityökoneen sähkökäytöt mahdollistavat tarkan vääntömomentin säädön, joka mahdollistaa työssä kuvatun kaltaisen järjestelmän toteuttamisen. Toteutettua järjestelmää simuloitiin MeVEA Oy:n ajoneuvomallinnukseen kehitetyssä simulaattorissa. Lisäksi järjestelmästä kehitettiin Visedo Oy:n sähkökäyttösimulaattoriin sopiva versio, jota testattiin Visedon sähkökäyttöjä simuloivan ohjelman kanssa. Simulointituloksien mukaan luistonesto estää vetäviä pyöriä luistamasta liukkaalla alustalla eikä toisaalta vähennä aiheetta kuljettajan asettamaa vääntömomenttia. Myös sähköinen tasauspyörästö toimi kuten oli suunniteltu. Työssä kehitetty luistonesto tarvitsee toimiakseen tiedon ajoneuvon kokonaismassasta, joten työssä kehitettiin myös tapa ajoneuvon massan estimoimiseksi ajoneuvon kiihdyttäessä. Massan estimointia testattiin pitävällä ja liukkaalla alustalla. Massan estimointi toimi simulaattoriympäristössä hyvällä tarkkuudella.

Computational modeling for irrigated agriculture planning. Part I: general description and linear programming

Linear programming models are effective tools to support initial or periodic planning of agricultural enterprises, requiring, however, technical coefficients that can be determined using computer simulation models. This paper, presented in two parts, deals with the development, application and tests of a methodology and of a computational modeling tool to support planning of irrigated agriculture activities. Part I aimed at the development and application, including sensitivity analysis, of a multiyear linear programming model to optimize the financial return and water use, at farm level for Jaíba irrigation scheme, Minas Gerais State, Brazil, using data on crop irrigation requirement and yield, obtained from previous simulation with MCID model. The linear programming model outputted a crop pattern to which a maximum total net present value of R$ 372,723.00 for the four years period, was obtained. Constraints on monthly water availability, labor, land and production were critical in the optimal solution. In relation to the water use optimization, it was verified that an expressive reductions on the irrigation requirements may be achieved by small reductions on the maximum total net present value.

Electrically driven fertilizer applicator controlled by fuzzy logic

The present study shows the development, simulation and actual implementation of a closed-loop controller based on fuzzy logic that is able to regulate and standardize the mass flow of a helical fertilizer applicator. The control algorithm was developed using MATLAB's Fuzzy Logic Toolbox. Both open and closed-loop simulations of the controller were performed in MATLAB's Simulink environment. The instantaneous deviation of the mass flow from the set point (SP), its derivative, the equipment´s translation velocity and acceleration were all used as input signals for the controller, whereas the voltage of the applicator's DC electric motor (DCEM) was driven by the controller as output signal. Calibration and validation of the rules and membership functions of the fuzzy logic were accomplished in the computer simulation phase, taking into account the system's response to SP changes. The mass flow variation coefficient, measured in experimental tests, ranged from 6.32 to 13.18%. The steady state error fell between -0.72 and 0.13g s-1 and the recorded average rise time of the system was 0.38 s. The implemented controller was able to both damp the oscillations in mass flow that are characteristic of helical fertilizer applicators, and to effectively respond to SP variations.

Structural modelling of liquid ZrO2 and glassy B2O3 by using AB INITIO Molecular Dynamics method

Atomic structure of ZrO2 and B2O3 was investigated in this work. New data under extreme conditions (T = 3100 K) was obtained for the liquid ZrO2 structure. A fractional number of boron was investigated for glassy structure of B2O3. It was shown that it is possible to obtain an agreement for the fractional number between NMR and DFT techniques using a suitable initial configuration.

Painevesityyppisen ydinvoimalaitoksen sekundääripiirin mallinnus

Tutkimuksen tavoitteena oli kehittää entistä tarkempi ja luotettavampi työkalu Loviisan ydinvoimalaitoksen ensimmäisen reaktoriyksikön sekundääripiirin 50-linjan stationääritilan toiminnan arviointiin. Toisena tavoitteena oli kartoittaa ja raportoida mallintamiseen käytetyn SOLVO-ohjelman kehitysmahdollisuuksia. Tutkimusten perusteella kehitettiin testatusti toimiva prosessimalli, joka dokumentoitiin ja validoitiin yksityiskohtaisesti. Tulevaisuudessa tapahtuvaa kehitystyötä, ja mallin käyttöä varten kehitettiin lisäksi Excel-pohjainen työkalu, jonka avulla SOLVO:n ja Excelin välinen integraatio voidaan myöhemmin julkaistavassa SOLVO:n versiossa viedä nykyistä pidemmälle. Mallintamistyön ohella tutkimuksen aikana selvitettiin olennaisimmat SOLVO:n erityispiirteet ja vahvuudet sekä kartoitettiin sen käyttöön liittyvät kehitystarpeet. Tärkeimpänä kehitysehdotuksena nousi esiin yksittäisissä komponenteissa suoritetun laskennan läpinäkyvyyden parantaminen. Seuraavassa kehitysvaiheessa myös komponenttikohtaiset laskentayhtälöt olisi suositeltavaa asettaa avoimiksi käyttäjäkohtaisille muutoksille. Työn aikana saavutettiin myös muita merkittäviä tuloksia, jotka liittyivät pääosin rinnak-kaisten 10- ja 50-linjojen välisiin yhteyksiin. Linjojen välisiä vaikutuksia analysoitaessa huomattiin niiden olevan olennaisessa asemassa erityisesti sarja-ajon aikana. Mikäli mallilla halutaan kuvata sekä sarja- että rinnanajoa, sen on käsitettävä molemmat linjat ja kaikki niihin liittyvät komponentit. Edellä mainitun lisäksi mallipohjaisen tarkastelun tuloksena tehtiin havaintoja, joiden perusteella nykyistä prosessia voidaan edelleen kehittää. Näistä havainnoista tärkeimpänä merivesipumppujen optimaalisen säätölämpötilan todettiin asettuvan 4,5 – 4,6 °C välille. Toinen huomio liittyi matalapaineturbiinien ulosvirtaushäviöihin, joihin hukataan juoksusta riippuen keskimäärin noin 10 kJ/kg enemmän entalpiaa kuin parhaassa mahdollisessa tapauksessa. Validoinnin yhteydessä havaituista pienistä poikkeamista huolimatta kehitetty malli vastaa hyvin laitokselta saatuja mittaustuloksia sekä muita samassa yhteydessä käytettyjä luotet-tavuuden arviointikriteerejä.

Flexible multibody approach in bone strain estimation during physical activity:

Bone strain plays a major role as the activation signal for the bone (re)modeling process, which is vital for keeping bones healthy. Maintaining high bone mineral density reduces the chances of fracture in the event of an accident. Numerous studies have shown that bones can be strengthened with physical exercise. Several hypotheses have asserted that a stronger osteogenic (bone producing) effect results from dynamic exercise than from static exercise. These previous studies are based on short-term empirical research, which provide the motivation for justifying the experimental results with a solid mathematical background. The computer simulation techniques utilized in this work allow for non-invasive bone strain estimation during physical activity at any bone site within the human skeleton. All models presented in the study are threedimensional and actuated by muscle models to replicate the real conditions accurately. The objective of this work is to determine and present loading-induced bone strain values resulting from physical activity. It includes a comparison of strain resulting from four different gym exercises (knee flexion, knee extension, leg press, and squat) and walking, with the results reported for walking and jogging obtained from in-vivo measurements described in the literature. The objective is realized primarily by carrying out flexible multibody dynamics computer simulations. The dissertation combines the knowledge of finite element analysis and multibody simulations with experimental data and information available from medical field literature. Measured subject-specific motion data was coupled with forward dynamics simulation to provide natural skeletal movement. Bone geometries were defined using a reverse engineering approach based on medical imaging techniques. Both computed tomography and magnetic resonance imaging were utilized to explore modeling differences. The predicted tibia bone strains during walking show good agreement with invivo studies found in the literature. Strain measurements were not available for gym exercises; therefore, the strain results could not be validated. However, the values seem reasonable when compared to available walking and running invivo strain measurements. The results can be used for exercise equipment design aimed at strengthening the bones as well as the muscles during workout. Clinical applications in post fracture recovery exercising programs could also be the target. In addition, the methodology introduced in this study, can be applied to investigate the effect of weightlessness on astronauts, who often suffer bone loss after long time spent in the outer space.

The energy efficiency of chilled beam systems in an office building at different climates

Besides the sustaining of healthy and comfortable indoor climate, the air conditioning system should also achieve for energy efficiency. The target indoor climate can be ob-tained with different systems; this study focuses on comparing the energy efficiency of different air conditioning room unit systems in different climates. The calculations are made with dynamic energy simulation software IDA ICE by comparing the indoor cli-mate and energy consumption of an office building with different systems in different climates. The aim of the study is to compare the energy efficiency of chilled beam systems to other common systems: variable air volume, fan coil and radiant ceiling systems. Besides the annual energy consumption also the sustainability of target indoor climate is compared between the simulations. Another aim is to provide conclusions to be used in the product development of the chilled beam systems’ energy efficiency. The adaptable chilled beam system and the radiant ceiling system prove to be energy efficient independent of the climate. The challenge of reliable comparison is that other systems are not able to reach the target indoor climate as well as the others. The complex calculation environment of the simulation software, made assumptions and excluding of the financial aspects complicate comparing the big picture. The results show that the development of the chilled beam systems should concentrate on energy efficient night heating, flexible demand based ventilation and capacity control and possibilities on integrating the best practices with other systems. 

Simuloinnin hyödyntäminen kotihoidon kehittämisessä

Ikääntyvien ihmisten kasvava määrä tulevina vuosikymmeninä kuormittaa kaupunkien kotihoitoa enenemässä määrin. Kaupunkien rajalliset resurssit ovat jo nyt koetuksella, eikä nykyiseen tilanteeseen ole nähtävissä huomattavaa parannusta tulevina vuosina. Kotihoidon henkilöstön määrää ei pystytä kasvattamaan riittävästi suhteessa kasvavien asiakasvirtojen kanssa, jotta korkea palvelun laatu voitaisiin taata myös tulevaisuudessa. Lahden kaupungin kotihoito pyrkii etsimään teknisiä ratkaisuja kotihoidon haasteisiin muun muassa kotihoidon töiden jakamiseen kehitetyllä optimointialgoritmilla sekä simuloinnilla. Tämä diplomityö käsittelee toimintatutkimuksen avulla simuloinnin tuomia hyötyjä sekä rajoitteita Lahden kotihoidon näkökulmasta. Launeen alueen kotihoidon haasteita käydään läpi neljässä eri työpajassa. Työssä esitetään Quest-simulointiohjelmiston ominaisuuksia, sekä Launeen alueen simulointimallin luomista aina suunnittelusta verifiointiin. Työn tuottama lisäarvo kotihoidon kehittämisessä tulee ilmi neljässä eri vaihtoehtoajossa kotihoitajien asiakkaalta toiselle kulkemien matkojen ja matkoihin käytettyjen aikojen mittaamisessa.