Numeerisia menetelmiä Java-kielellä

Java-kieli on ottanut paikkansa web-ohjelmoinnin alueella, mutta tieteellisissä laskentatehtävissä se on lyhyehkön historiansa aikana jäänyt muiden ohjelmointikielten varjoon. Tutkielmassa selvitettiin, miten kieli soveltuu matemaattisten ongelmien ratkaisuun. Tutkimusta varten kehitettiin esimerkkiohjelmia eri numeerisen matematiikan osaalueille, kuten integrointiin, derivointiin, interpolointiin ja juurenhakuun; painopiste oli lineaarialgebran sovelluksissa. Eri matriisihajotelmien käyttöön perustuvia esimerkkejä tehtiin useampia. Kaikki ohjelmat toteutettiin siten, että niitä on mahdollista käyttää verkossa erilaisilla tietokonekokoonpanoilla. Tämä on kiinteä osa Java-kielen ideologiaa. Tutkielmaan kuuluvalla web-sivustolla kaikki ohjelmat lähdekoodeineen ovat kiinnostuneiden käytettävissä. Sivustoa on mahdollista kehittää ja laajentaa entisestään, sillä monet numeriikan osa-alueet jäivät vielä käsittelemättä. Ohjelmat lähdekoodeineen sekä kaikkien valmiiden luokkien lähdekoodit löytyvät myös tutkielman mukana tulevalta CD-ROM-levyltä. Esimerkkien pohjalta saatujen kokemusten perusteella todettiin, että Java-kielellä on mahdollista toteuttaa matemaattisia ohjelmia, vaikka kielellä onkin puutteensa; esimerkiksi Javan omat matemaattiset luokat ovat sellaisenaan riittämättömät vaativiin sovelluksiin. Tämä saattaa osittain selittää laimean kiinnostukseen kielen mahdollisuuksiin tieteellisessä käytössä. Java on kuitenkin vielä kehittyvä kieli, joten tulevaisuudessa aukeavat mahdollisuudet jäävät nähtäväksi.

Liikkuvien työkoneiden valmistettavuuden kehittäminen teollisessa liiketoimintaverkostossa

Diplomityön tavoitteena oli kehittää Pilomac – konsernin päähankkijayrityksien tuotteiden valmistettavuutta yhteistyössä yrityksien suunnitteluosastojen ja teräsrakenteita valmistavien toimittajayrityksien kanssa. Päähankkija-yritysten, Junttan Oy:n ja Logset Oy:n, osavalmistusten ulkoistamisen myötä toimittajasuhteet ovat vähitellen muuttumassa verkostomaiseen toimintatapaan. Täten on tärkeää muuttaa ja kehittää tuotteiden valmistettavuuden mahdollistavat toimintamallit vastaamaan uutta toimintatapaa. Keskeinen perusmenetelmä valmistettavuuden huomioimisessa on suunnittelun ja valmistuksen välisen tuotekehitysyhteistyön syventäminen rinnakkaissuunnitteluksi, (CE). Verkostokumppaneiden välinen yhteistyö perustuu avoimuuteen, luottamukseen ja molempia osapuolia hyödyttävään jatkuvaan kehitystyöhön. Verkostomainen toimintatapa mahdollistaa luontevasti tuotteen suunnittelu- ja kehitysvastuiden jaottelun yritysten ydinosaamisen mukaan. Onnistuneen työnjaon myötä resurssit lisääntyvät ja valmistusteknologiat, suunnittelu ja laatu kehittyvät ja monipuolistuvat. Työn aihetta tutkittiin soveltavassa osassa benchmarkingin, nykytilakuvauksien sekä toimittajaverkoston analysoinnin avulla. Toimittajaverkoston analysointi tehtiin laajan verkostokumppanikyselyn avulla, josta selvisi Junttan Oy:n toimittajaverkoston resurssit ja kyvykkyys. Kyselyssä selvitettiin myös nykyisten toimittajien näkemyksiä valmistettavuuden kehittämisestä, kumppaneille asetettavista yhteistyövaatimuksista sekä näiden toimintamallien vaikutuksista tuotteiden kilpailukyvyn parantumiseen. Työn tuloksena selvisivät osa-alueet, joita Junttan Oy:n kannattaa hyödyntää tulevaisuudessa enemmän sekä toimintamallit, jotka mahdollistavat tuotteiden valmistettavuuden jatkuvan kehittämisen.

Components of customer value in nurse call solutions

This study aimed to identify the value components of nurse call solutions. The value creation of such systems was analyzed by using a framework that was created based on the existing customer value literature. The empirical part of the study was conducted as a multiple-case study by using qualitative research methods. The data for the analysis was gathered through structured interviews in ten Finnish eldercare centers. The results indicate that a nurse call solution creates value for eldercare centers by increasing the safety of the residents, and by improving the efficiency of the staff while also providing cost savings.

Influence of Heat Treatment on Strength Properties of Finger-jointed Components

The purpose for the thesis was to study the thermo treatment of finger-jointed wood. The thesis concentrated on examining the tensile and bending strength of finger-jointed and thermo treated wood. The aim was to find out how different treatment temperature levels and adhesives influence the strength of wood that has been finger-jointed before heat treatment. Secondary objectives were to examine the influence of the treatment time at one temperature, determine differences in the strength between the joints in heartwood and sapwood, examine the visual appearance of the finger joints after the treatment and establish possibilities to reach a characteristic strength level corresponding to C14. Only minor differences in strength properties were measured between the finger-jointed wood treatments II and III. A greater difference was shown between these two treatment temperatures I, which lead to reduced strength. The average strength of joints glued with adhesive 2 was higher after treatments II and III compared to those glued with the adhesive 1. At the treatment temperature I, the adhesive 1 strength properties were at the same level compared to the adhesive 2 or better. There were not any significant differences.

Switching components for medium voltage drives

Nowadays power drives are the essential part almost of all technological processes. Improvement of efficiency and reduction of losses require development of semiconductor switches. It has a particular meaning for the constantly growing market of renewable sources, especially for wind turbines, which demand more powerful semiconductor devices for control with growth of power. Also at present semiconductor switches are the key component in energy transmission, optimization of generation and network connection. The aim of this thesis is to make a survey of contemporary semiconductor components, showing difference in structures, advantages, disadvantages and most suitable applications. There is topical information about voltage, frequency and current limits of different switches. Study tries to compare dimensions and price of different components. Main manufacturers of semiconductor components are presented with the review of devices produced by them, and a conclusion about their availability was made. IGBT is selected as a main component in this study, because nowadays it is the most attractive component for usage in power drives, especially at the low levels of medium voltage. History of development of IGBT structure, static and dynamic characteristics are considered. Thesis tells about assemblies and connection of components and problems which can appear. One of key questions about semiconductor materials and their future development was considered. For the purpose of comparison strong and weak sides of different switches, calculation of losses of IGBT and its basic competitor – IGCT is presented. This master’s thesis makes an effort to answer the question if there are at present possibilities of accurate selection of switches for electrical drives of different rates of power and looks at future possible ways of development of semiconductor market.

Identification of Some Additional Loss Components in High-Power Low-Voltage Permanent Magnet Generators

Permanent magnet generators (PMG) represent the cutting edge technology in modern wind mills. The efficiency remains high (over 90%) at partial loads. To improve the machine efficiency even further, every aspect of machine losses has to be analyzed. Additional losses are often given as a certain percentage without providing any detailed information about the actual calculation process; meanwhile, there are many design-dependent losses that have an effect on the total amount of additional losses and that have to be taken into consideration. Additional losses are most often eddy current losses in different parts of the machine. These losses are usually difficult to calculate in the design process. In this doctoral thesis, some additional losses are identified and modeled. Further, suggestions on how to minimize the losses are given. Iron losses can differ significantly between the measured no-load values and the loss values under load. In addition, with embedded magnet rotors, the quadrature-axis armature reaction adds losses to the stator iron by manipulating the harmonic content of the flux. It was, therefore, re-evaluated that in salient pole machines, to minimize the losses and the loss difference between the no-load and load operation, the flux density has to be kept below 1.5 T in the stator yoke, which is the traditional guideline for machine designers. Eddy current losses may occur in the end-winding area and in the support structure of the machine, that is, in the finger plate and the clamping ring. With construction steel, these losses account for 0.08% of the input power of the machine. These losses can be reduced almost to zero by using nonmagnetic stainless steel. In addition, the machine housing may be subjected to eddy current losses if the flux density exceeds 1.5 T in the stator yoke. Winding losses can rise rapidly when high frequencies and 10–15 mm high conductors are used. In general, minimizing the winding losses is simple. For example, it can be done by dividing the conductor into transposed subconductors. However, this comes with the expense of an increase in the DC resistance. In the doctoral thesis, a new method is presented to minimize the winding losses by applying a litz wire with noninsulated strands. The construction is the same as in a normal litz wire but the insulation between the subconductors has been left out. The idea is that the connection is kept weak to prevent harmful eddy currents from flowing. Moreover, the analytical solution for calculating the AC resistance factor of the litz-wire is supplemented by including an end-winding resistance in the analytical solution. A simple measurement device is developed to measure the AC resistance in the windings. In the case of a litz-wire with originally noninsulated strands, vacuum pressure impregnation (VPI) is used to insulate the subconductors. In one of the two cases studied, the VPI affected the AC resistance factor, but in the other case, it did not have any effect. However, more research is needed to determine the effect of the VPI on litz-wire with noninsulated strands. An empirical model is developed to calculate the AC resistance factor of a single-layer formwound winding. The model includes the end-winding length and the number of strands and turns. The end winding includes the circulating current (eddy currents that are traveling through the whole winding between parallel strands) and the main current. The end-winding length also affects the total AC resistance factor.

The pH-dependent phase distribution of wood pitch components in papermaking processes

Wood contains only a very small amount of lipophilic extractives, commonly known as wood pitch. The pitch is known to cause severe problems in papermaking processes. The amount of pitch in process waters can be decreased by seasoning of the raw material prior to pulping, pulp washing, removal of pitch by flotation, adsorption of pitch onto various mineral surfaces, and retention of pitch to the fibre material by cationic polymers. The aim of this study was to determine the influence of pH on some of the methods used for pitch control. Experiments were performed using laboratory-made wood pitch emulsions with varying pH, salt concentration, hemicellulose concentration and pitch composition. These emulsions were used to study the phase distribution of resin and fatty acids, the colloidal stability of pitch with and without steric stabilisation by galactoglucomannans, and the interactions between wood pitch and mineral particles. Purification of unbleached and peroxidebleached mill process water was performed by froth flotation in combination with a foaming agent. The distribution of resin and fatty acids (RFAs) between colloidal pitch droplets and the water phase was very dependent on pH. At pH 3, almost all of the RFAs were attached to the pitch droplets, while increasing the pH led to increasing concentration of dissolved RFAs in the water phase. The presence of salt shifted the release of RFAs towards higher pH, while lower ratio of neutral pitch in the emulsion resulted in release of RFAs at lower pH. It was also seen that the dissolution and adsorption of RFAs at sudden pHchanges takes place very quickly. Colloidal pitch was more stable against electrolyte-induced aggregation at higher pH, due to its higher anionic charge. The concentration of cationic polymers needed to aggregate colloidal pitch also increased with increasing pH. The surface characteristics of solid particles, such as amount of charged groups, were very important for understanding their interactions with colloidal wood pitch. Water-soluble galactoglucomannans stabilised the colloidal pitch sterically against aggregation, but could not completely prevent interactions between wood pitch and hydrophilic particles. Froth flotation of unbleached and peroxidebleached process water showed that the pitch could be removed more effectively and selectively at low pH, compared to at neutral pH. The pitch was removed more effectively, using lower concentrations of foaming agent, from peroxide-bleached water than from unbleached water. The results show that pH has a major impact on various pulping and papermaking processes. It determines the anionic charge of the colloidal pitch and the solubility of certain pitch components. Because of this, the pH influences the effectiveness of pitch retention and removal of pitch. The results indicate that pitch problems could be diminished by acknowledging the importance of pH in various papermaking processes.

[Carte marine depuis le Cap de Bonne-Espérance jusqu'à Java]

Kartta kuuluu A. E. Nordenskiöldin kokoelmaan

Thermal reactions of the major hydrocarbon components of biomass gasification gas

Gasification of biomass is an efficient method process to produce liquid fuels, heat and electricity. It is interesting especially for the Nordic countries, where raw material for the processes is readily available. The thermal reactions of light hydrocarbons are a major challenge for industrial applications. At elevated temperatures, light hydrocarbons react spontaneously to form higher molecular weight compounds. In this thesis, this phenomenon was studied by literature survey, experimental work and modeling effort. The literature survey revealed that the change in tar composition is likely caused by the kinetic entropy. The role of the surface material is deemed to be an important factor in the reactivity of the system. The experimental results were in accordance with previous publications on the subject. The novelty of the experimental work lies in the used time interval for measurements combined with an industrially relevant temperature interval. The aspects which are covered in the modeling include screening of possible numerical approaches, testing of optimization methods and kinetic modelling. No significant numerical issues were observed, so the used calculation routines are adequate for the task. Evolutionary algorithms gave a better performance combined with better fit than the conventional iterative methods such as Simplex and Levenberg-Marquardt methods. Three models were fitted on experimental data. The LLNL model was used as a reference model to which two other models were compared. A compact model which included all the observed species was developed. The parameter estimation performed on that model gave slightly impaired fit to experimental data than LLNL model, but the difference was barely significant. The third tested model concentrated on the decomposition of hydrocarbons and included a theoretical description of the formation of carbon layer on the reactor walls. The fit to experimental data was extremely good. Based on the simulation results and literature findings, it is likely that the surface coverage of carbonaceous deposits is a major factor in thermal reactions.

Developing an introductory object-oriented programming course

The state of the object-oriented programming course in Lappeenranta University of Technology had reached the point, where it required changes to provide better learning opportunities and thus the learning outcomes. Based on the student feedback the course was partially dated and ineffective. The components of the course were analysed and the ineffective elements were removed and new methods were introduced to improve the course. The major changes included the change from traditional teaching methods to reverse classroom method and the use of Java as the programming language. The changes were measured by the student feedback, lecturer’s observations and comparison to previous years. The feedback suggested that the changes were successful; the course received higher overall grade than before.

Exploring business models for medical games: Key components and challenges

The costs of health care are going up in many countries. In order to provide affordable and effective health care solutions, new technologies and approaches are constantly being developed. In this research, video games are presented as a possible solution to the problem. Video games are fun, and nowadays most people like to spend time on them. In addition, recent studies have pointed out that video games can have notable health benefits. Health games have already been developed, used in practice, and researched. However, the bulk of health game studies have been concerned with the design or the effectiveness of the games; no actual business studies have been conducted on the subject, even though health games often lack commercial success despite their health benefits. This thesis seeks to fill this gap. The specific aim of this thesis is to develop a conceptual business model framework and empirically use it in explorative medical game business model research. In the first stage of this research, a literature review was conducted and the existing literature analyzed and synthesized into a conceptual business model framework consisting of six dimensions. The motivation behind the synthesis is the ongoing ambiguity around the business model concept. In the second stage, 22 semi-structured interviews were conducted with different professionals within the value network for medical games. The business model framework was present in all stages of the empirical research: First, in the data collection stage, the framework acted as a guiding instrument, focusing the interview process. Then, the interviews were coded and analyzed using the framework as a structure. The results were then reported following the structure of the framework. In the results, the interviewees highlighted several important considerations and issues for medical games concerning the six dimensions of the business model framework. Based on the key findings of this research, several key components of business models for medical games were identified and illustrated in a single figure. Furthermore, five notable challenges for business models for medical games were presented, and possible solutions for the challenges were postulated. Theoretically, these findings provide pioneering information on the untouched subject of business models for medical games. Moreover, the conceptual business model framework and its use in the novel context of medical games provide a contribution to the business model literature. Regarding practice, this thesis further accentuates that medical games can offer notable benefits to several stakeholder groups and offers advice to companies seeking to commercialize these games.

Implementation of Quantitative Reaction-based Model Refinement

Building a computational model for complex biological systems is an iterative process. It starts from an abstraction of the process and then incorporates more details regarding the specific biochemical reactions which results in the change of the model fit. Meanwhile, the model’s numerical properties such as its numerical fit and validation should be preserved. However, refitting the model after each refinement iteration is computationally expensive resource-wise. There is an alternative approach which ensures the model fit preservation without the need to refit the model after each refinement iteration. And this approach is known as quantitative model refinement. The aim of this thesis is to develop and implement a tool called ModelRef which does the quantitative model refinement automatically. It is both implemented as a stand-alone Java application and as one of Anduril framework components. ModelRef performs data refinement of a model and generates the results in two different well known formats (SBML and CPS formats). The development of this tool successfully reduces the time and resource needed and the errors generated as well by traditional reiteration of the whole model to perform the fitting procedure.

Characterization and Investigation on Material Compatibilities of Building Integrated Photovoltaic Module Components

Building Integrated Photovoltaics (BIPV) are considered as the future of photovoltaic (PV) technology. The advantage of BIPV system is its multi-functionality; they fulfil the functions of a building envelope with the added benefit of generating power by replacing the traditional roofing and façade materials with PV that generate power. In this thesis, different types of PV cells and modules have been described in detail with their efficiencies and usage trends in the last decade. The different BIPV products for roof and façade are discussed in detail giving several examples. The electricity generation potential of BIPV in selected countries is compared with their actual electricity consumption. Further, the avoided greenhouse gas (GHG) emissions associated with electricity generation from traditional sources and transportation and distribution (T&D) losses are calculated. The results illustrate huge savings in GHGs. In BIPV different types of façade and backsheets are used. In this thesis, selected backsheets and façade were characterized in terms of their surface structure identification using infrared spectroscopy (FTIR-ATR), scanning electron microscopy with energy dispersive X-ray (SEM-EDX) and physical characterization using surface energy measurements. By using FTIR-ATR, surface polymeric materials were identified and with SEM-EDX, identification of the surface elements was possible. Surface energy measurements were useful in finding the adhesives and knowing the surface energies of the various backsheets and façade. The strength of adhesion between the facade and backsheets was studied using peel test. Four different types of adhesives were used to study the fracture pattern and peel tests values to identify the most suitable adhesive. It was found out that pretreatment increased the adhesive strength significantly.

Hyvät ohjelmointiperiaatteet Java-kielessä

Ammattimaisessa ohjelmistokehityksessä pyritään tuottamaan ohjelmia, jotka ovat ylläpidettäviä ja uudelleenkäytettäviä. Näiden piirteiden aikaansaamiseksi ohjelmistokehittäjien on hyvä tuntea ohjelmointiperiaatteita, joita noudattamalla kehittäjät voivat luoda parempia ratkaisuja ohjelmointiongelmiin. Tutkielmassa perehdytään ohjelmointiperiaatteista kertovaan kirjallisuuteen, ja esitetään yleisiä olio-ohjelmoinnin ohjelmointiperiaatteita sekä Robert C. Martinin (2002) kehittämä SOLID-malli. Tutkimusaihe rajataan luokkatason ohjelmointiperiaatteisiin. SOLID-malli sisältää viisi luokkatason ohjelmointiperiaatetta, jotka auttavat ohjelmoijia parantamaan ohjelman ylläpidettävyyttä ja uudelleenkäyttöä. Ohjelmointiperiaatteet esitetään Java-kielellä yksinkertaisten esimerkkitapausten avulla. Tutkielmassa esitetyt ohjelmointiperiaatteet eivät ole sidottuja ainoastaan Javaan, vaan ne on suunniteltu yleishyödyllisiksi olio-ohjelmoinnin periaatteiksi riippumatta käytettävästä ohjelmointikielestä.