A novel approachfor assessing the fatigue strength of ultrasonic impact treated welded structures.

It is commonly observed that complex fabricated structures subject tofatigue loading fail at the welded joints. Some problems can be corrected by proper detail design but fatigue performance can also be improved using post-weld improvement methods. In general, improvement methods can be divided into two main groups: weld geometry modification methods and residual stress modification methods. The former remove weld toe defects and/or reduce the stress concentrationwhile the latter introduce compressive stress fields in the area where fatigue cracks are likely to initiate. Ultrasonic impact treatment (UIT) is a novel post-weld treatment method that influences both the residual stress distribution andimproves the local geometry of the weld. The structural fatigue strength of non-load carrying attachments in the as-welded condition has been experimentally compared to the structural fatigue strength of ultrasonic impact treated welds. Longitudinal attachment specimens made of two thicknesses of steel S355 J0 have been tested for determining the efficiency of ultrasonic impacttreatment. Treated welds were found to have about 50% greater structural fatigue strength, when the slope of the S-N-curve is three. High mean stress fatigue testing based on the Ohta-method decreased the degree of weld improvement only 19%. This indicated that the method could be also applied for large fabricated structures operating under high reactive residual stresses equilibrated within the volume of the structure. The thickness of specimens has no significant effect tothe structural fatigue strength. The fatigue class difference between 5 mm and 8 mm specimen was only 8%. It was hypothesized that the UIT method added a significant crack initiation period to the total fatigue life of the welded joints. Crack initiation life was estimated by a local strain approach. Material parameters were defined using a modified Uniform Material Law developed in Germany. Finite element analysis and X-ray diffraction were used to define, respectively, the stress concentration and mean stress. The theoretical fatigue life was found to have good accuracy comparing to experimental fatigue tests.The predictive behaviour of the local strain approach combined with the uniformmaterial law was excellent for the joint types and conditions studied in this work.

Hienopaperimassojen lujuusominaisuudet nopeassa vetokuormituksessa

Työssä verrattiin koivu-, akaasia- ja eucalyptussellujen käyttökelpoisuutta hienopapereiden kuituraaka-aineena. Kirjallisuusosassa todettiin radan hallinnan paperikoneiden avoimissa vienneissä riippuvan käytetyn geometrian lisäksi lujuus- ja relaksaatio-ominaisuuksista. Kuituverkoston käyttäytymiseen jännityksen alaisena vaikuttavat kuitudimensiot, kosteus ja lämpötila sekä kuituverkostoon kohdistetun jännityksen nopeus ja määrä. Relaksaationopeus ja vetolujuus kasvavat kuivilla papereilla vetonopeuden lisääntyessä. Kosteuspitoisuuden kasvattaminen alentaa puukuiduissa olevien polymeerien lasisiirtymälämpötilaa, jonka seurauksena vetolujuus ja relaksaatiokireys laskevat voimakkaasti. Kosteuspitoisuuden kasvaessa murtovenymä kasvaa lähes lineaarisesti ja repäisylujuus sekä murtotyö saavuttavat maksiminsa tietyssä kosteuspitoisuudessa. Kokeellisessa osassa keskityttiin hienopaperimassojen lujuus- ja relaksaatiokäyttäytymisen selvittämiseen nopeassa vetokuormituksessa. Lisäksi määritettiin laatu-, massa- ja rakenneominaisuuksia valituille koepisteille. Muuttujina kokeissa olivat massojen kuiva-ainepitoisuudet ja jauhatusolosuhteet sekä havusellun osuus hienopaperimassoissa.CSF-tasoon 350 ml jauhetuista näytteistä parhaat lujuus ja relaksaatio-ominaisuudet olivat koivulla ja heikoimmat akaasialla. Erot koepisteiden välillä korostuivat pienellä havusellun määrällä, mutta kaventuivat huomattavasti havusellun määrää lisättäessä. Samaan vetolujuuteen jauhettaessa massojen erot poistuvat kokonaan. Kuivilla näytteillä löydettiin erinomainen korrelaatio myötölujuuden ja relaksaatiokireyden välille. Puristinkuivien näytteiden relaksaatiokireyksiä voidaan kokeiden valossa ennustaa parhaiten kuivien näytteiden vetolujuuksista. Myös elastisten venymien osuuksille ja kuituseinämien paksuuksille löydettiin selvä yhteys.Eucalyptus- ja akaasiamassojen erinomaisuus hienopapereiden raaka-aineena korostui niiden optisissa ominaisuuksissa, erityisesti korkeana valonsirontana. Verrattaessa samassa vetolujuudessa ja relaksaatiokireydessä valonsirontakertoimien arvoja havaittiin akaasian olevan paras koivun jäädessä heikoimmaksi. Lisäksi akaasian ja eucalyptuksen kapeat kuitujakaumat ovat edullisia painokoneessa värin tasaisen imeytymisen kannalta. Akaasian pienet ja taipuisat kuidut antavat paperille tasaisen pinnan ja siten painatuksessa tasaisen painoalustan.

Bordetella pertussis - Vaccination and Strain Variation

Pertussis or whooping cough is a highly contagious vaccine-preventable disease of the human respiratory tract caused by the Bordetella pertussis bacteria. In Finland, pertussis vaccinations were started in 1952 leading to a dramatic decrease in the morbidity and mortality. In the late 1990s, the incidence of pertussis increased despite the high vaccination coverage. Strain variation has been connected to the re-emergence of pertussis in countries with long history of pertussis vaccination. In 2005, the pertussis vaccine and the vaccination schedule were changed in Finland. The molecular epidemiology and the strain variation of the B. pertussis isolates were examined in Finland and in countries with similar (France) and different (Sweden) vaccination history. Continuous evolution of the B. pertussis population in Finland was observed since the 1950s, and the recently circulating isolates were antigenically different from the vaccine strains. Comparison of the circulating isolates from Finland, France and Sweden did not refer to significant differences. Certain type of strains noticed in France already in 1994 mainly caused the recent epidemics in Sweden (1999) and in Finland (2003-4). On several occasions, a new type of strains first appeared in Sweden and some years later in Finland. The B. pertussis isolates from the infants were shown to be similar to those from the other age groups. It is suggested that the strains originate from the same reservoir among adolescents and adults. The strain variation does not seem to have a major effect on the morbidity among recently vaccinated individuals, but it might play a role among those who are in the waning phase of immunity. The incidence of pertussis in Finland has remained low since the change of the vaccination programme. This might be related to the epidemic nature of pertussis and the near future will show the real effectiveness of the new vaccination programme. At present, many infants are infected because they are too young to be immunised with the current schedule. New strategies or vaccines are needed to protect those who are the most vulnerable.

Development of Color Difference Equations Matching to Human Vision System

Research on color difference evaluation has been active in recent thirty years. Several color difference formulas were developed for industrial applications. The aims of this thesis are to develop the color density which is denoted by comb g and to propose the color density based chromaticity difference formulas. Color density is derived from the discrimination ellipse parameters and color positions in the xy , xyY and CIELAB color spaces, and the color based chromaticity difference formulas are compared with the line element formulas and CIE 2000 color difference formulas. As a result of the thesis, color density represents the perceived color difference accurately, and it could be used to characterize a color by the attribute of perceived color difference from this color.

The cultural dimension in focus : promoting awareness of diversity and respect for difference in a Finland-Swedish EFL classroom

This study addresses the role of EFL education, its potential and shortcomings, and the challenges the future of EFL education will bring. It is argued that new societal demands and the limited time we have at our disposal in the classroom make it necessary to rethink goals and content and move away from the transmissionof limited sets of facts and information to helping students develop awareness and competences that can be applied in many different situations, also in a perspective of lifelong learning. The overall aim of the current study is to problematize and increase understanding of the implementation of cultural aspects in the language classroom by addressing the interrelated what, why and how of the cultural dimension within EFL education. This has been conducted by means of theoretical explorations into the area, alongside an attempt at promoting intercultural competence (IC) in a more systematic and insightful manner within my own educational praxis. The focus of the intercultural work in the classroom was on the promotion of awareness of difference and diversity, as well as respect for such difference through the ability to decenter from cultural norms and behavior that previously have been taken for granted. These are two elements that have been suggested as fundamental for other work with IC in the classroom and for the realization of important aspects of the underlying values of basic education. In the context of this study, IC comprises several interconnected components supportingeach other in a variety of ways, with the further aim being interaction with and respect for difference in general, not only concerning e.g. representatives ofcertain English-speaking communities. The methodology was informed by action research, with myself in the role of the teacher-researcher or the reflective practitioner. For the purpose of the project I was authorized to take on the EFL education for the three years of upper comprehensive school of one random class of students originally assigned to one of the language teachers of the selected Finland-Swedish school. Thus, the class of 17 students was not specifically chosen for the project, and the aims and contents chosen for the development project were placed within the framework of the ordinary curriculum. By exploring the students¿ insights concerning different English-speaking cultural groups, mainly through a set of questionnaires, it was possible to outline the work with the cultural dimension in the classroom for the following three years. Work progress was evaluated at specific stages, and the final project evaluations were conducted through individual student interviews in grade 9. The interviews were focused on possible development of students¿ insights concerning different aspects of the cultural dimension. In particular this concerned awareness of difference and diversity, including modification of stereotypes, as well as the ability to decenterin order to be better able to respect such difference. I also explored students¿ awareness and views of the activities and approaches used in class, as well asaffordances both inside and outside the EFL classroom in relation to these intended insights. A further focus area was the perceived relevance to students of different aspects of the cultural dimension. The frameworks and approaches adopted for the work in the classroom all have in common that they are based on a constructivist framework, where knowledge is constructed and reconstructed through interaction with one¿s social and cultural environment, including interaction with others. Reflective processes precede or are simultaneous with the learning of basic factual knowledge. This entails a view of learning as a progression from simple to more complex models rather than as a progression from facts to understanding and analysis. Here, the development of intercultural competence is seen asa cyclical process, or along a spiral curriculum, from simple to more complex levels through a combination of cognitive, affective and behavioral elements within a framework of experiential learning. This project has shown one possible wayforward concerning the development of intercultural competence within EFL education through a more systematic and comprehensive approach regarding linguistic and cultural aspects. The evaluation of the educational process explored in the study suggests the possibilities for work with the promotion of awareness of difference and diversity concerning some specific context that, based on students¿ prior knowledge and preconceptions, would benefit from further work. In this case, the specific context primarily concerned different aspects of both cultural and linguistic conditions in the UK. It is also suggested that many students developed the ability to decenter, described in the study as integral to being able to respect otherness. What still remains to be explored are more individualized approaches considering students¿ different levels of departure. Further work alsoneeds to be put into how to apply insights gained in these specific situations to more general contexts. It is also necessary to explore the use of the suggested approaches in a wider range of different contexts.

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.

Hitsatun rakenteen lujuustarkastelu kokeellisesti määritetyn kuormitushistorian perusteella

Työssä tutkittiin jätteen murskauksesta murskaimeen aiheutuvia kuormituksia vastusvenymäliuskamittauksilla. Eri jätetyyppien aiheuttamia kuormituksia tutkittiin erillisinä tapauksina ja näistä tyyppikuormituksista johdettiin rakenteen normaalia käyttöä vastaava kuormitushistoria käyttäen painokertoimia eri tyyppikuormien kesken. Murskaimen runkorakennetta tutkittiin FE-analyysillä käyttäen kuormituksena kenttämittauksilla saatua todellista kuormitusta. FE-menetelmällä tutkittiin väsymisen kannalta kriittisiä kohtia rakenteesta. Tulosten perusteella kriittisiin yksityiskohtiin laadittiin parannusehdotuksia, joiden perusteella yhteistyössä työn teettäjän kanssa laadittiin uudet rakenneratkaisut. Rakenteen kestoikä määritettiin väsymisvaurion kannalta kriittisimmän yksityiskohdan mukaan. Kestoiän määrittämiseen käytettiin Palmgren-Miner menetelmää ja Palmgren-Miner menetelmästä johdettua ekvivalentin jännitysvaihtelun menetelmää. Muutosten jälkeen rakenne täyttää sille asetetun suunnittelukestoiän käytettyjen menetelmien perusteella.

Prediction of 3D structure and ligand-binding properties : ABC transporters and flavodiiron proteins from Synechocystis sp. strain PCC 6803

Cyanobacteria are unicellular, non-nitrogen-fixing prokaryotes, which perform photosynthesis similarly as higher plants. The cyanobacterium Synechocystis sp. strain PCC 6803 is used as a model organism in photosynthesis research. My research described herein aims at understanding the function of the photosynthetic machinery and how it responds to changes in the environment. Detailed knowledge of the regulation of photosynthesis in cyanobacteria can be utilized for biotechnological purposes, for example in the harnessing of solar energy for biofuel production. In photosynthesis, iron participates in electron transfer. Here, we focused on iron transport in Synechocystis sp. strain PCC 6803 and particularly on the environmental regulation of the genes encoding the FutA2BC ferric iron transporter, which belongs to the ABC transporter family. A homology model built for the ATP-binding subunit FutC indicates that it has a functional ATPbinding site as well as conserved interactions with the channel-forming subunit FutB in the transporter complex. Polyamines are important for the cell proliferation, differentiation and apoptosis in prokaryotic and eukaryotic cells. In plants, polyamines have special roles in stress response and in plant survival. The polyamine metabolism in cyanobacteria in response to environmental stress is of interest in research on stress tolerance of higher plants. In this thesis, the potd gene encoding an polyamine transporter subunit from Synechocystis sp. strain PCC 6803 was characterized for the first time. A homology model built for PotD protein indicated that it has capability of binding polyamines, with the preference for spermidine. Furthermore, in order to investigate the structural features of the substrate specificity, polyamines were docked into the binding site. Spermidine was positioned very similarly in Synechocystis PotD as in the template structure and had most favorable interactions of the docked polyamines. Based on the homology model, experimental work was conducted, which confirmed the binding preference. Flavodiiron proteins (Flv) are enzymes, which protect the cell against toxicity of oxygen and/or nitric oxide by reduction. In this thesis, we present a novel type of photoprotection mechanism in cyanobacteria by the heterodimer of Flv2/Flv4. The constructed homology model of Flv2/Flv4 suggests a functional heterodimer capable of rapid electron transfer. The unknown protein sll0218, encoded by the flv2-flv4 operon, is assumed to facilitate the interaction of the Flv2/Flv4 heterodimer and energy transfer between the phycobilisome and PSII. Flv2/Flv4 provides an alternative electron transfer pathway and functions as an electron sink in PSII electron transfer.

Open research data policies, what makes the difference?

Poster at Open Repositories 2014, Helsinki, Finland, June 9-13, 2014

Kartongin fysikaalisten ominaisuuksien vaikutus muovautuvuuteen

Työn tavoitteena oli kehittää menetelmä, jolla voitaisiin arvioida veto-ominaisuuksien avulla konvertointikoneen prässäysnopeuden ja muottien lämpötilan vaikutuksia kartongin muovautuvuuteen. Kirjallisuusosassa käsiteltiin kartongin muovautuvuuteen vaikuttavia ominaisuuksia sekä vetolujuuteen vaikuttavia tekijöitä. Lisäksi käsiteltiin kosteuden vaikutusta muovautuvuuteen sekä esiteltiin vuokakonvertointiprosessin periaate ja muovin sekä kartongin käyttäytymisen erot konvertointiprosessissa. Kokeellinen osa jakaantui kolmeen osaan. Esikokeissa tutkittiin laboratoriomittauksilla vetonopeuden ja kosteuden muutosten vaikutusta erilaisten kaupallisten kartonkimateriaalien vetolujuuteen ja murtovenymään. Tulosten perusteella valittiin prässäysnopeudet ja kosteustaso 2D- testauslaitteella suoritettuihin esi-pilot-mittakaavan kokeisiin sekä varsinaiseen pilot-koeajoon. Pilot-koeajossa pyrittiin arvioimaan prässäysnopeuden ja muottien lämpötilan vaikutuksia muovautuvuuteen vetolujuusarvojen avulla. Prässäysnopeudella ja vetolujuuslaitteen nopeudella ei havaittu yhteneväisyyksiä, jotta voitaisiin arvioida kartongin muovautuvuutta. Muovautuvuutta voidaan kuitenkin arvioida epäonnistuneisuusluvulla, jonka laskentapa kehitettiin työn aikana. Epäonnistuneisuusluku kuvaa hyvin kartongin muovautuvuutta ja on menetelmänä helppo, mutta sen heikkoutena on repeämien mittaamisen aiheuttama epätarkkuus. Esikokeissa havaittiin myös muovipäällysteiden veto-ominaisuuksien vastaavan kartongin ominaisuuksia 65 %:n suhteellisessa kosteudessa, jonka valittiin siten olevan optimaalinen olosuhde pilot-mittakaavan koeajoihin.

Feasibility of industrial implementation of laser cutting into paper making machine

Laser cutting implementation possibilities into paper making machine was studied as the main objective of the work. Laser cutting technology application was considered as a replacement tool for conventional cutting methods used in paper making machines for longitudinal cutting such as edge trimming at different paper making process and tambour roll slitting. Laser cutting of paper was tested in 70’s for the first time. Since then, laser cutting and processing has been applied for paper materials with different level of success in industry. Laser cutting can be employed for longitudinal cutting of paper web in machine direction. The most common conventional cutting methods include water jet cutting and rotating slitting blades applied in paper making machines. Cutting with CO2 laser fulfils basic requirements for cutting quality, applicability to material and cutting speeds in all locations where longitudinal cutting is needed. Literature review provided description of advantages, disadvantages and challenges of laser technology when it was applied for cutting of paper material with particular attention to cutting of moving paper web. Based on studied laser cutting capabilities and problem definition of conventional cutting technologies, preliminary selection of the most promising application area was carried out. Laser cutting (trimming) of paper web edges in wet end was estimated to be the most promising area where it can be implemented. This assumption was made on the basis of rate of web breaks occurrence. It was found that up to 64 % of total number of web breaks occurred in wet end, particularly in location of so called open draws where paper web was transferred unsupported by wire or felt. Distribution of web breaks in machine cross direction revealed that defects of paper web edge was the main reason of tearing initiation and consequent web break. The assumption was made that laser cutting was capable of improvement of laser cut edge tensile strength due to high cutting quality and sealing effect of the edge after laser cutting. Studies of laser ablation of cellulose supported this claim. Linear energy needed for cutting was calculated with regard to paper web properties in intended laser cutting location. Calculated linear cutting energy was verified with series of laser cutting. Practically obtained laser energy needed for cutting deviated from calculated values. This could be explained by difference in heat transfer via radiation in laser cutting and different absorption characteristics of dry and moist paper material. Laser cut samples (both dry and moist (dry matter content about 25-40%)) were tested for strength properties. It was shown that tensile strength and strain break of laser cut samples are similar to corresponding values of non-laser cut samples. Chosen method, however, did not address tensile strength of laser cut edge in particular. Thus, the assumption of improving strength properties with laser cutting was not fully proved. Laser cutting effect on possible pollution of mill broke (recycling of trimmed edge) was carried out. Laser cut samples (both dry and moist) were tested on the content of dirt particles. The tests revealed that accumulation of dust particles on the surface of moist samples can take place. This has to be taken into account to prevent contamination of pulp suspension when trim waste is recycled. Material loss due to evaporation during laser cutting and amount of solid residues after cutting were evaluated. Edge trimming with laser would result in 0.25 kg/h of solid residues and 2.5 kg/h of lost material due to evaporation. Schemes of laser cutting implementation and needed laser equipment were discussed. Generally, laser cutting system would require two laser sources (one laser source for each cutting zone), set of beam transfer and focusing optics and cutting heads. In order to increase reliability of system, it was suggested that each laser source would have double capacity. That would allow to perform cutting employing one laser source working at full capacity for both cutting zones. Laser technology is in required level at the moment and do not require additional development. Moreover, capacity of speed increase is high due to availability high power laser sources what can support the tendency of speed increase of paper making machines. Laser cutting system would require special roll to maintain cutting. The scheme of such roll was proposed as well as roll integration into paper making machine. Laser cutting can be done in location of central roll in press section, before so-called open draw where many web breaks occur, where it has potential to improve runability of a paper making machine. Economic performance of laser cutting was done as comparison of laser cutting system and water jet cutting working in the same conditions. It was revealed that laser cutting would still be about two times more expensive compared to water jet cutting. This is mainly due to high investment cost of laser equipment and poor energy efficiency of CO2 lasers. Another factor is that laser cutting causes material loss due to evaporation whereas water jet cutting almost does not cause material loss. Despite difficulties of laser cutting implementation in paper making machine, its implementation can be beneficial. The crucial role in that is possibility to improve cut edge strength properties and consequently reduce number of web breaks. Capacity of laser cutting to maintain cutting speeds which exceed current speeds of paper making machines what is another argument to consider laser cutting technology in design of new high speed paper making machines.

The Role of Structural Imperfections in Sr2FeMoO6 Thin Films

In this work, Sr2FeMoO6 (SFMO) thin films were studied with the main focus on their magnetic and magneto-transport properties. The fabrication process of pulsed laser deposited SFMO films was first optimized. Then the effects of strain, film thickness and substrate were thoroughly investigated. In addition to these external factors, the effect of intrinsic defects on the magnetic properties of SFMO were also clarified. Secondly, the magnetoresistivity mechanims of SFMO films were studied and a semiempirical model of the temperature dependence of resistivity was introduced. The films were grown on single crystal substrates using a ceramic target made with sol-gel method. The structural characterization of the films were carried out with X-ray diffraction, atomic force microscopy, transmission electron microscopy and high kinetic energy photoelectron spectroscopy. The magnetic properties were measured with SQUID magnetometer and the magneto-transport properties by magnetometer with a resistivity option. SFMO films with the best combination of structural and magnetic properties were grown in Ar atmosphere at 1050 °C . Their magnetic properties could not be improved by the ex situ post-annealing treatments aside from the treatments in ultra-high vacuum conditions. The optimal film thickness was found to be around 150 nm and only small improvement in the magnetic properties with decreasing strain was observed. Instead, the magnetic properties were observed to be highly dependent on the choice of the substrate due to the lattice mismatch induced defects, which are best avoided by using the SrTiO3 substrate. The large difference in the Curie temperature and the saturation magnetization between the SFMO thin film and polycrystalline bulk samples was connected to the antisite disorder and oxygen vacancies. Thus, the Curie temperature of SFMO thin films could be improved by increasing the amount of oxygen vacancies for example with ultra-high vacuum treatments or improving the B-site ordering by further optimization of the deposition parameters. The magneto-transport properties of SFMO thin films do not follow any conventional models, but the temperature dependence of resistivity was succesfully described with a model of two spin channel system. Also, evidences that the resistivity-temperature behaviour of SFMO thin films is dominated by the structural defects, which reduce the band gap in the majority spin band were found. Moreover, the magnetic field response of the resistivity in SFMO thin films were found to be superposition of different mechanisms that seems to be related to the structural changes in the film.

Modelling the colour difference by artificial neural network

This thesis work studies the modelling of the colour difference using artificial neural network. Multilayer percepton (MLP) network is proposed to model CIEDE2000 colour difference formula. MLP is applied to classify colour points in CIE xy chromaticity diagram. In this context, the evaluation was performed using Munsell colour data and MacAdam colour discrimination ellipses. Moreover, in CIE xy chromaticity diagram just noticeable differences (JND) of MacAdam ellipses centres are computed by CIEDE2000, to compare JND of CIEDE2000 and MacAdam ellipses. CIEDE2000 changes the orientation of blue areas in CIE xy chromaticity diagram toward neutral areas, but on the whole it does not totally agree with the MacAdam ellipses. The proposed MLP for both modelling CIEDE2000 and classifying colour points showed good accuracy and achieved acceptable results.