Höyryturbiinin käytönaikaisen suorituskyvyn seuranta

Tässä diplomityössä jatkettiin Loviisan voimalaitoksen höyryturbiinien suorituskyvyn parannuspotentiaalien tutkimusta. Tavoitteena oli kehittää laitoksen höyryturbiinien suorituskyvyn käytönaikaisia on-line-mittauksia. Selvityksessä perehdyttiin norjalaisen IFE:n kehittämään stationääritilan TEMPOohjelmaan( The Thermal Performance Monitoring And Optimisation system), sen käyttöohjeisiin ja toimintaperiaatteisiin. Työssä esiteltiin laajasti tiedon yhteensovittamisen laskentateoriaa, johon TEMPOn toiminta perustuu. Työssä tarkasteltiin turbiinin todellista paisuntaprosessia, koska sen ymmärtäminen on tärkeässä osassa turbiinin suorituskyvyn valvonnassa. Tutkimuksessa esiteltiin myös turbiineille mahdollisia vikoja sekä niiden syntymisprosesseja. Työssä tarkasteltiin TEMPOn sovittamien tulostiedostojen analysointiohjelman toimivuutta havaitsemalla itse aiheutettuja poikkeamia todellisiin mittaustiedostoihin. Analysointiohjelmalla muodostettuja kuvaajia vertailtiin todellisen prosessin ajotilanteen kuvaajiin ja tarkasteltiin, kuinka poikkeamia on mahdollista havaita kuvaajien avulla. TEMPO-ohjelmalle löydettiin tutkimuksen edetessä kehittämisehdotuksia. Näillä muutoksilla ohjelma saadaan mallintamaan Loviisan voimalaitoksen turbiiniprosessia tarkemmin ja tuloksista saadaan hyödyllisempiä.

Talviaikainen happitilanne eräissä Pohjois-Savon järvissä vuosina 1997-2008

Pohjois-Savossa seurattiin talviaikaista happitilannetta vuosina 1997-2008. Seurannan kohteena oli neljä pienehköä järveä (Iso-Valkeinen, Kevätön, Kolmisoppi ja Vehmasjärvi), jotka ovat erityyppisiä syvyydeltään, rehevyystasoltaan ja humuspitoisuudeltaan. Näiden esimerkkijärvien oli tarkoitus antaa yleisemminkin viitteitä happitilanteen kehityksestä talven aikana. Alkutalven tulosten perusteella annettiin vuosittain tiedote, jossa arvioitiin happikatojen mahdollisuutta kevättalven kuluessa. Yleisöllä oli myös mahdollisuus seurata happi- ja lämpötilatuloksia Pohjois-Savon ympäristökeskuksen verkkopalvelun kautta. Hapenkulutusnopeus oli rehevimmässä seurantajärvessä kaksinkertainen verrattuna karumpiin ja syvyyden myötä ero vain korostui. Pohjanläheisessä vesikerroksessa 1 mg/l:n happipitoisuus kului karuissa järvissä noin kahdessa viikossa ja rehevässä noin kolmessa päivässä. Vuosien välinen vaihtelu oli kuitenkin hyvin suurta. Vaihtelu oli suurta myös karuissa järvissä. Veden jäätymisajankohdalla ja veden lämpötilalla on merkittävä vaikutus siihen, millainen kevättalven happitilanteesta muodostui. Seurantajärvien aineiston perusteella voidaan karkeasti arvioida, että kuukauden viivästyminen jäätymisessä tai vesipatsaan viilentyminen ennen jäätymistä asteen verran kylmemmäksi merkitsevät noin kolmanneksen korkeampaa happipitoisuutta kevättalvella. Vesipatsaan happitilanteen heikentymisen sekä ravinne- ja rautapitoisuuksien välillä todettiin vahvat yhteydet. Kaikkien järvien aineistossa happitilanteen heikkeneminen johti voimakkaimmin alusveden ammoniumtyppi-, kokonaisfosfori- ja rautapitoisuuksien kasvuun. Pitoisuusmuutokset olivat talven aikana suurimmat rehevimmässä kohdejärvessä, Kevättömässä, jossa kokonaisfosforipitoisuudet keskimäärin kymmenkertaistuivat, fosfaattifosforipitoisuudet kasvoivat keskimäärin 20-kertaisiksi ja rautapitoisuudet yli seitsenkertaisiksi.

Phytosociological surveys: tools for weed science?

In simple terms, a phytosociological survey is a group of ecological evaluation methods whose aim is to provide a comprehensive overview of both the composition and distribution of plant species in a given plant community. To understand the applicability of phytosociological surveys for weed science, as well as their validity, their ecological basis should be understood and the most suitable ones need to be chosen, because cultivated fields present a relatively distinct group of selecting factors when compared to natural plant communities. For weed science, the following sequence of steps is proposed as the most suitable: (1) overall infestation; (2) phytosociological tables/graphs; (3) intra-characterization by diversity; (4) inter-characterization and grouping by cluster analysis. A summary of methods is established in order to assist Weed Science researchers through their steps into the realm of phytosociology.

CO2:n adsorptio Loviisan voimalaitoksen päästöilmasta 14C-päästöjen määrittämiseksi

Tämän kandidaatintyön tavoitteena oli selvittää mahdollisuuksia 14C:n kemiallisten muotojen eriyttämiseen käyttäen Loviisan voimalaitoksella olemassa olevaa näytteenkeräyslaitteistoa. Lisäksi tarkoituksena oli selvittää parhaiten tähän käyttötarkoitukseen soveltuva zeoliittityyppiä tyypeistä 4A, 5A ja 13X. Työn kirjallisessa osassa käsitellään ydinvoimalaitoksen C14-päästöjä keskittyen pääosin Loviisan VVER-laitokseen. Adsorption osalta esitellään kaupallisesti käytettyjä adsorptiomateriaaleja ja paneudutaan adsorptioon fysikaalisena ja kemiallisena ilmiönä. Lisäksi esitellään kahden desorptiomenetelmän perusperiaatteet. Kirjallisen osan lopussa kootaan tutkimukseen vaikuttavia tekijöitä ja esitellään aiemmin käytössä ollut näytteenkeräyslaitteisto. Kokeellisessa osassa esitellään työssä käytetyt laitteistot. Lisäksi on kuvattu mittausten suoritus nestetuikelaskurilla. Tämän jälkeen työssä esitellään mittaustuloksien käsittely ja näin saadut tulokset.

Energy saving potential in reservoir pumping

Pumping systems account for up to 22 % of the energy consumed by electrical motors in European industry. Many studies have shown that there is also a lot of potential for energy savings in these systems with the improvement of devices, flow control or surrounding sys-tem. The best method for more energy efficient pumping has to be found for each system separately. This thesis studies how energy saving potential in reservoir pumping system is affected by surrounding variables, such as the static head variation and friction factor. The objective is to create generally applicable graphs to quickly compare methods for reducing pumping system’s energy costs. The gained results are several graphs showcasing how the chosen variables affect energy saving potential of the pumping system in one specific case. To judge if these graphs are generally applicable, more testing with different pumps and environments are required.

Efficient Optimization Algorithms for Nonlinear Data Analysis

Identification of low-dimensional structures and main sources of variation from multivariate data are fundamental tasks in data analysis. Many methods aimed at these tasks involve solution of an optimization problem. Thus, the objective of this thesis is to develop computationally efficient and theoretically justified methods for solving such problems. Most of the thesis is based on a statistical model, where ridges of the density estimated from the data are considered as relevant features. Finding ridges, that are generalized maxima, necessitates development of advanced optimization methods. An efficient and convergent trust region Newton method for projecting a point onto a ridge of the underlying density is developed for this purpose. The method is utilized in a differential equation-based approach for tracing ridges and computing projection coordinates along them. The density estimation is done nonparametrically by using Gaussian kernels. This allows application of ridge-based methods with only mild assumptions on the underlying structure of the data. The statistical model and the ridge finding methods are adapted to two different applications. The first one is extraction of curvilinear structures from noisy data mixed with background clutter. The second one is a novel nonlinear generalization of principal component analysis (PCA) and its extension to time series data. The methods have a wide range of potential applications, where most of the earlier approaches are inadequate. Examples include identification of faults from seismic data and identification of filaments from cosmological data. Applicability of the nonlinear PCA to climate analysis and reconstruction of periodic patterns from noisy time series data are also demonstrated. Other contributions of the thesis include development of an efficient semidefinite optimization method for embedding graphs into the Euclidean space. The method produces structure-preserving embeddings that maximize interpoint distances. It is primarily developed for dimensionality reduction, but has also potential applications in graph theory and various areas of physics, chemistry and engineering. Asymptotic behaviour of ridges and maxima of Gaussian kernel densities is also investigated when the kernel bandwidth approaches infinity. The results are applied to the nonlinear PCA and to finding significant maxima of such densities, which is a typical problem in visual object tracking.

Quenching of the intrinsic fluorescence of bovine serum albumin by chlorpromazine and hemin

The binding of chlorpromazine (CPZ) and hemin to bovine serum albumin was studied by the fluorescence quenching technique. CPZ is a widely used anti-psychotic drug that interacts with blood components, influences bioavailability, and affects function of several biomolecules. Hemin is an important ferric residue of hemoglobin that binds within the hydrophobic region of albumin with high specificity. Quenching of the intrinsic fluorescence of bovine serum albumin (BSA) was observed by selectively exciting tryptophan residues at 290 nm. Emission spectra were recorded in the range from 300 to 450 nm for each quencher addition. Stern-Volmer graphs were plotted, and the quenching constant estimated for BSA solution titrated with hemin at 25ºC was 1.44 (± 0.05) x 10(5) M-1. Results showed that bovine albumin tryptophans are not equally accessible to CPZ, in agreement with the idea that polar or charged quenchers have more affinity for amino acid residues on the outer wall of the protein. Hemin added to albumin solution at a molar ratio of 1:1 quenched about 25% of their fluorescence. The quenching effect of CPZ on albumin-hemin solution was stronger than on pure BSA. This increase can be the result of combined conformational changes in the structure of albumin caused firstly by hemin and then by CPZ. Our results suggest that the primary binding site for hemin on bovine albumin may be located asymmetrically between the two tryptophans along the sequence formed by subdomains IB and IIA, closer to tryptophan residue 212.

Texture analysis of computed tomography images of acute ischemic stroke patients

Computed tomography (CT) images are routinely used to assess ischemic brain stroke in the acute phase. They can provide important clues about whether to treat the patient by thrombolysis with tissue plasminogen activator. However, in the acute phase, the lesions may be difficult to detect in the images using standard visual analysis. The objective of the present study was to determine if texture analysis techniques applied to CT images of stroke patients could differentiate between normal tissue and affected areas that usually go unperceived under visual analysis. We performed a pilot study in which texture analysis, based on the gray level co-occurrence matrix, was applied to the CT brain images of 5 patients and of 5 control subjects and the results were compared by discriminant analysis. Thirteen regions of interest, regarding areas that may be potentially affected by ischemic stroke, were selected for calculation of texture parameters. All regions of interest for all subjects were classified as lesional or non-lesional tissue by an expert neuroradiologist. Visual assessment of the discriminant analysis graphs showed differences in the values of texture parameters between patients and controls, and also between texture parameters for lesional and non-lesional tissue of the patients. This suggests that texture analysis can indeed be a useful tool to help neurologists in the early assessment of ischemic stroke and quantification of the extent of the affected areas.

Brain tissue segmentation using q-entropy in multiple sclerosis magnetic resonance images

The loss of brain volume has been used as a marker of tissue destruction and can be used as an index of the progression of neurodegenerative diseases, such as multiple sclerosis. In the present study, we tested a new method for tissue segmentation based on pixel intensity threshold using generalized Tsallis entropy to determine a statistical segmentation parameter for each single class of brain tissue. We compared the performance of this method using a range of different q parameters and found a different optimal q parameter for white matter, gray matter, and cerebrospinal fluid. Our results support the conclusion that the differences in structural correlations and scale invariant similarities present in each tissue class can be accessed by generalized Tsallis entropy, obtaining the intensity limits for these tissue class separations. In order to test this method, we used it for analysis of brain magnetic resonance images of 43 patients and 10 healthy controls matched for gender and age. The values found for the entropic q index were 0.2 for cerebrospinal fluid, 0.1 for white matter and 1.5 for gray matter. With this algorithm, we could detect an annual loss of 0.98% for the patients, in agreement with literature data. Thus, we can conclude that the entropy of Tsallis adds advantages to the process of automatic target segmentation of tissue classes, which had not been demonstrated previously.

Trypan blue exclusion assay by flow cytometry

Dye exclusion tests are used to determine the number of live and dead cells. These assays are based on the principle that intact plasma membranes in live cells exclude specific dyes, whereas dead cells do not. Although widely used, the trypan blue (TB) exclusion assay has limitations. The dye can be incorporated by live cells after a short exposure time, and personal reliability, related to the expertise of the analyst, can affect the results. We propose an alternative assay for evaluating cell viability that combines the TB exclusion test and the high sensitivity of the flow cytometry technique. Previous studies have demonstrated the ability of TB to emit fluorescence when complexed with proteins. According to our results, TB/bovine serum albumin and TB/cytoplasmic protein complexes emit fluorescence at 660 nm, which is detectable by flow cytometry using a 650-nm low-pass band filter. TB at 0.002% (w/v) was defined as the optimum concentration for distinguishing unstained living cells from fluorescent dead cells, and fluorescence emission was stable for 30 min after cell treatment. Although previous studies have shown that TB promotes green fluorescence quenching, TB at 0.002% did not interfere with green fluorescence in human live T-cells stained with anti-CD3/fluorescein isothiocyanate (FITC) monoclonal antibody. We observed a high correlation between the percentage of propidium iodide+CD3/FITC+ and TB+CD3/FITC+ cells, as well as similar double-stained cell profiles in flow cytometry dot-plot graphs. Taken together, the results indicate that a TB exclusion assay by flow cytometry can be employed as an alternative tool for quick and reliable cell viability analysis.

Implementing Green IT approach for transferring Big Data over Parallel Data Link

The whole research of the current Master Thesis project is related to Big Data transfer over Parallel Data Link and my main objective is to assist the Saint-Petersburg National Research University ITMO research team to accomplish this project and apply Green IT methods for the data transfer system. The goal of the team is to transfer Big Data by using parallel data links with SDN Openflow approach. My task as a team member was to compare existing data transfer applications in case to verify which results the highest data transfer speed in which occasions and explain the reasons. In the context of this thesis work a comparison between 5 different utilities was done, which including Fast Data Transfer (FDT), BBCP, BBFTP, GridFTP, and FTS3. A number of scripts where developed which consist of creating random binary data to be incompressible to have fair comparison between utilities, execute the Utilities with specified parameters, create log files, results, system parameters, and plot graphs to compare the results. Transferring such an enormous variety of data can take a long time, and hence, the necessity appears to reduce the energy consumption to make them greener. In the context of Green IT approach, our team used Cloud Computing infrastructure called OpenStack. It’s more efficient to allocated specific amount of hardware resources to test different scenarios rather than using the whole resources from our testbed. Testing our implementation with OpenStack infrastructure results that the virtual channel does not consist of any traffic and we can achieve the highest possible throughput. After receiving the final results we are in place to identify which utilities produce faster data transfer in different scenarios with specific TCP parameters and we can use them in real network data links.

Development and chemical characterization of flour obtained from the external mesocarp of "pequizeiro" fruit

The objective of this work was to develop a recommendation for the chemical peeling of pequi fruit and characterize the flour obtained from the external mesocarp of "Pequizeiro", pequi tree (Caryocar brasiliense Camb.). The technology applied to obtain the external mesocarp pequi flour included the epicarp removal with NaOH solution. The Response Surface Method was used to optimize the chemical peeling process by applying the Central Composite Rotatable Design, with eleven trials including three replicates at the central point, varying the NaOH aqueous solution concentration and fruit immersion time. The mass loss was evaluated through the analysis of variance and using bi and three dimensional graphs. The chemical characteristics of the external mesocarp pequi flour evaluated were: moisture content, ashes, proteins, lipids, total carbohydrates, dietary fiber, and some minerals. The best combination for an efficient removal of the fruit peel with the lowest mass loss was reached with 7.05 minutes of immersion in a 5.08 g.L-1 NaOH aqueous solution. This study indicated that the external mesocarp pequi flour is a food source rich in dietary fiber, carbohydrates, ashes, magnesium, calcium, manganese, and copper, but it is poor in lipids, zinc, and iron.

Computational models for and from biology : simple gene assembly and reaction systems

The advancement of science and technology makes it clear that no single perspective is any longer sufficient to describe the true nature of any phenomenon. That is why the interdisciplinary research is gaining more attention overtime. An excellent example of this type of research is natural computing which stands on the borderline between biology and computer science. The contribution of research done in natural computing is twofold: on one hand, it sheds light into how nature works and how it processes information and, on the other hand, it provides some guidelines on how to design bio-inspired technologies. The first direction in this thesis focuses on a nature-inspired process called gene assembly in ciliates. The second one studies reaction systems, as a modeling framework with its rationale built upon the biochemical interactions happening within a cell. The process of gene assembly in ciliates has attracted a lot of attention as a research topic in the past 15 years. Two main modelling frameworks have been initially proposed in the end of 1990s to capture ciliates’ gene assembly process, namely the intermolecular model and the intramolecular model. They were followed by other model proposals such as templatebased assembly and DNA rearrangement pathways recombination models. In this thesis we are interested in a variation of the intramolecular model called simple gene assembly model, which focuses on the simplest possible folds in the assembly process. We propose a new framework called directed overlap-inclusion (DOI) graphs to overcome the limitations that previously introduced models faced in capturing all the combinatorial details of the simple gene assembly process. We investigate a number of combinatorial properties of these graphs, including a necessary property in terms of forbidden induced subgraphs. We also introduce DOI graph-based rewriting rules that capture all the operations of the simple gene assembly model and prove that they are equivalent to the string-based formalization of the model. Reaction systems (RS) is another nature-inspired modeling framework that is studied in this thesis. Reaction systems’ rationale is based upon two main regulation mechanisms, facilitation and inhibition, which control the interactions between biochemical reactions. Reaction systems is a complementary modeling framework to traditional quantitative frameworks, focusing on explicit cause-effect relationships between reactions. The explicit formulation of facilitation and inhibition mechanisms behind reactions, as well as the focus on interactions between reactions (rather than dynamics of concentrations) makes their applicability potentially wide and useful beyond biological case studies. In this thesis, we construct a reaction system model corresponding to the heat shock response mechanism based on a novel concept of dominance graph that captures the competition on resources in the ODE model. We also introduce for RS various concepts inspired by biology, e.g., mass conservation, steady state, periodicity, etc., to do model checking of the reaction systems based models. We prove that the complexity of the decision problems related to these properties varies from P to NP- and coNP-complete to PSPACE-complete. We further focus on the mass conservation relation in an RS and introduce the conservation dependency graph to capture the relation between the species and also propose an algorithm to list the conserved sets of a given reaction system.

Glycemic index and glycemic load of tropical fruits and the potential risk for chronic diseases

The objective was to determine the glycemic index and glycemic load of tropical fruits and the potential risk for chronic diseases. Nine fruits were investigated: coconut water (for the purpose of this study, coconut water was classified as a “fruit”), guava, tamarind, passion fruit, custard apple, hog plum, cashew, sapodilla, and soursop. The GI and GL were determined according to the Food and Agriculture Organization protocol. The GL was calculated taking into consideration intake recommendation guidelines; 77.8% of the fruits had low GI although significant oscillations were observed in some graphs, which may indicate potential risks of disease. Coconut water and custard apple had a moderate GI, and all fruits had low GL. The fruits evaluated are healthy and can be consumed following the daily recommended amount. However, caution is recommended with fruits causing early glycemic peak and the fruits with moderated GI (coconut water and custard apple).

An exploration of gifted and highly able adolescents' experiences with stress and coping /

This narrative case study explored gifted and highly able adolescents' experiences with stress and coping. Nine students, ages 13-18, at 2 independent schools in southern Ontario, participated. They completed the Adolescent Coping Scale (Frydenberg & Lewis, 1993), and I generated individualized graphs of coping strategies. Participants talked about experiences they perceived as stressful in their academic, personal, social, and familial settings during a 60-90 minute one-on-one audiotaped interview. During the interview, each participant made observations about their own coping strategies profile. The interview was analyzed to identify stressor and coping themes. Participants completed a writing or art task to record perceptions of stress and coping. The 3 data sources were used to craft 9 individual story portraits, from which 5 main stressor themes emerged: issues of time; relationships, emotions, and communication; ethical, moral, and spiritual issues; global issues; and silences, or stressors not talked about in depth. Coping themes were: seeking relaxing activities; having positive attitudes and making wise choices; maintaining relationships with peers and family; understanding the role of faith and moral beliefs; having a supportive environment; knowing your own personality type; being aware of negative coping strategies; and keeping busy and avoiding stressfiil issues. The narratives are important because they present teenagers talking about their socioemotional worlds. The present findings provide empirical groundwork for curriculum development in affective education and highlight the importance of socioemotional development for future research in the area of giftedness and adolescence.