10 resultados para Calculus of variations
em Doria (National Library of Finland DSpace Services) - National Library of Finland, Finland
Resumo:
Immobilization of Burkholderia cepacia Lipase: Kinetic Resolution in Organic Solvents, Ionic Liquids and in Their Mixtures Biocatalysis opens the door to green and sustainable processes in synthetic chemistry allowing the preparation of single enantiomers, since the enzymes are chiral and accordingly able to catalyze chemical reactions under mild conditions. Immobilization of enzymes enhances process robustness, often stabilizes and activates the enzyme, and enables reuse of the same enzyme preparation in multiple cycles. Although hundreds of variations of immobilization methods exist, there is no universal method to yield the highly active, selective and stable enzyme catalysts. Therefore, new methods need to be developed to obtain suitable catalysts for different substrates and reaction environments. Lipases are the most widely used enzymes in synthetic organic chemistry. The literature part together with the experimental part of this thesis discusses of the effects of immobilization methods mostly used to enhance lipase activity, stability and enantioselectivity. Moreover, the use of lipases in the kinetic resolution of secondary alcohols in organic solvents and in ionic liquids is discussed. The experimental work consists of the studies of immobilization of Burkholderia cepacia lipase (lipase PS) using three different methods: encapsulation in sol-gels, cross-linked enzyme aggregates (CLEAs) and supported ionic liquids enzyme catalysts (SILEs). In addition, adsorption of lipase PS on celite was studied to compare the results obtained with sol-gels, CLEAs and SILEs. The effects of immobilization on enzyme activity, enantioselectivity and hydrolysis side reactions were studied in kinetic resolution of three secondary alcohols in organic solvents, in ionic liquids (ILs), and in their mixtures. Lipase PS sol-gels were shown to be active and stable catalysts in organic solvents and solvent:IL mixtures. CLEAs and SILEs were highly active and enantioselective in organic solvents. Sol-gels and SILEs were reusable in several cycles. Hydrolysis side reaction was suppressed in the presence of sol-gels and CLEAs.
Resumo:
The conventional activated sludge processes (CAS) for the treatment of municipal wastewater are going to be outdated gradually due to more stringent environmental protection laws and regulations. The Membrane bioreactors (MBRs) are the most promising modern technology widely accepted in the world of wastewater treatment due to their highly pronounced features such as high quality effluent, less foot print and working under high MLSS concentration. This research project was carried out to investigate the feasibility and effectiveness of MBR technology compare to the CAS process based on the scientific facts and results. The pilot scale MBR pilot plant was run for more than 150 days and the analysis results were evaluated. The prime focus of the project was to evaluate the correlation of permeate flux under different operating MLSS concentrations. The permeate flux was found almost constant regardless of variations in MLSS concentrations. The removal of micropollutant such as heavy metals, PCPPs, PFCs, steroidal hormones was also studied. The micropollutant removal performance of MBR process was found relatively effective than CAS process. Furthermore, the compatibility of submerged membranes within the bioreactor had truly reduced the process footprint.
Resumo:
Most of the applications of airborne laser scanner data to forestry require that the point cloud be normalized, i.e., each point represents height from the ground instead of elevation. To normalize the point cloud, a digital terrain model (DTM), which is derived from the ground returns in the point cloud, is employed. Unfortunately, extracting accurate DTMs from airborne laser scanner data is a challenging task, especially in tropical forests where the canopy is normally very thick (partially closed), leading to a situation in which only a limited number of laser pulses reach the ground. Therefore, robust algorithms for extracting accurate DTMs in low-ground-point-densitysituations are needed in order to realize the full potential of airborne laser scanner data to forestry. The objective of this thesis is to develop algorithms for processing airborne laser scanner data in order to: (1) extract DTMs in demanding forest conditions (complex terrain and low number of ground points) for applications in forestry; (2) estimate canopy base height (CBH) for forest fire behavior modeling; and (3) assess the robustness of LiDAR-based high-resolution biomass estimation models against different field plot designs. Here, the aim is to find out if field plot data gathered by professional foresters can be combined with field plot data gathered by professionally trained community foresters and used in LiDAR-based high-resolution biomass estimation modeling without affecting prediction performance. The question of interest in this case is whether or not the local forest communities can achieve the level technical proficiency required for accurate forest monitoring. The algorithms for extracting DTMs from LiDAR point clouds presented in this thesis address the challenges of extracting DTMs in low-ground-point situations and in complex terrain while the algorithm for CBH estimation addresses the challenge of variations in the distribution of points in the LiDAR point cloud caused by things like variations in tree species and season of data acquisition. These algorithms are adaptive (with respect to point cloud characteristics) and exhibit a high degree of tolerance to variations in the density and distribution of points in the LiDAR point cloud. Results of comparison with existing DTM extraction algorithms showed that DTM extraction algorithms proposed in this thesis performed better with respect to accuracy of estimating tree heights from airborne laser scanner data. On the other hand, the proposed DTM extraction algorithms, being mostly based on trend surface interpolation, can not retain small artifacts in the terrain (e.g., bumps, small hills and depressions). Therefore, the DTMs generated by these algorithms are only suitable for forestry applications where the primary objective is to estimate tree heights from normalized airborne laser scanner data. On the other hand, the algorithm for estimating CBH proposed in this thesis is based on the idea of moving voxel in which gaps (openings in the canopy) which act as fuel breaks are located and their height is estimated. Test results showed a slight improvement in CBH estimation accuracy over existing CBH estimation methods which are based on height percentiles in the airborne laser scanner data. However, being based on the idea of moving voxel, this algorithm has one main advantage over existing CBH estimation methods in the context of forest fire modeling: it has great potential in providing information about vertical fuel continuity. This information can be used to create vertical fuel continuity maps which can provide more realistic information on the risk of crown fires compared to CBH.
Resumo:
Tutkimukseni käsittelee suomen kielen sanaston kehitystä 1800-luvulla eli aikana, jolloin suomen kielestä kehittyi monialainen sivistyskieli. Esimerkkiaineistona on yhden erikoisalan, maantieteen sanasto. Suomen kirjakieli syntyi 1500-luvulla, mutta aluksi kirjoitettua kieltä tarvittiin pääasiassa uskonnollisissa yhteyksissä. 1800-luvun aikana kielen käyttöalat monipuolistuivat ja uutta sanastoa tarvittiin monien erikoisalojen tarpeisiin. Ryhdyttiin tietoisesti kääntämään tietokirjallisuutta ja kirjoittamaan eri aiheista. Tutkimukseni selvittää maantieteen sanaston kehittymistä sadassa vuodessa erityisesti maantieteen oppikirjoissa. Tutkimus kuvaa sanaston kehitystä teoreettisesti uudenlaisista lähtökohdista tarkastelemalla leksikaalista variaatiota. Variaatiota on kuvattu tarkasti sekä yksittäisten käsitteiden nimitysten kehityksenä että ilmiönä yleisesti. Tutkimus hyödyntää myös kognitiivista lähestymistapaa, etenkin sosiokognitiivisen terminologian teoriaa. Aineiston analyysin pohjalta syntyy kuva sanaston kehityksestä ja vakiintumisesta. Tutkimus kuvaa myös tapoja, joilla uusia käsitteitä nimettiin. Se pohtii eri nimeämistapojen suhdetta sekä kirjoittajien ja aikalaisten roolia sanaston vakiintumisessa. 1800-luvun maantieteen sanastossa on runsaasti variaatiota; vain harvojen käsitteiden nimitykset ovat vakiintuneita tai vakiintuvat nopeasti. Tämän variaation kuvaaminen leksikaalisena variaationa osoittautui tutkimuksessa hyväksi metodiksi. Koska kirjakieli oli vakiintumatonta, nimityksissä esiintyy paljon kontekstuaalista variaatiota esimerkiksi sanojen kirjoitusasuissa. Kirjoittajat myös pohtivat havainnollista tapaa nimetä käsitteitä, ja tästä aiheutuu onomasiologista variaatiota. Semasiologinen variaatio taas kertoo käsitejärjestelmän vakiintumattomuudesta. Aineiston sanaston lähtökohdat ovat vanhan kirjasuomessa, mutta tältä pohjalta luodaan valtava määrä uutta sanastoa tai otetaan aiemmin kirjakielessä käytettyjä nimityksiä uuteen merkitykseen. Tärkeä rooli on sekä nimitysten muodostamisella kotoisista aineksista että kääntämisellä, jossa malli saadaan toisesta kielestä mutta nimitysten ainekset ovat omaperäisiä.
Resumo:
Tämä diplomityö on tehty Sunila Oy:n sulfaattisellutehtaalle. Työssä käsitellään sekundäärilämmön hyödyntämisen ja käytön periaatteita sulfaattisellutehtaassa. Tehtaan primääri- ja sekundääritaseet on laskettu tehtaan informaatiojärjestelmästä saatujen tietojen avulla. Taselaskelmat on määritetty sekä talvi- että kesätilanteelle. Niiden perusteella on tarkasteltu hyödynnettävissä olevaa sekundäärilämpöä. Lisäksi työssä on käsitelty mahdollisuuksia käyttää apulauhduttimeen johdettavaa höyryä kaukolämmön tuottamiseen. Lämmöntuotannon vaihteluiden vuoksi työssä on käsitelty lämmön varastoimista kaukolämpöakkuun. Kaukolämpöä on laskelmien mukaan saatavissa talvella keskimäärin 19 MW.
Resumo:
Mottling is one of the key defects in offset-printing. Mottling can be defined as unwanted unevenness of print. In this work, diameter of a mottle spot is defined between 0.5-10.0 mm. There are several types of mottling, but the reason behind the problem is still not fully understood. Several commercial machine vision products for the evaluation of print unevenness have been presented. Two of these methods used in these products have been implemented in this thesis. The one is the cluster method and the other is the band-pass method. The properties of human vision system have been taken into account in the implementation of these two methods. An index produced by the cluster method is a weighted sum of the number of found spots, and an index produced by band-pass method is a weighted sum of coefficients of variations of gray-levels for each spatial band. Both methods produce larger indices for visually poor samples, so they can discern good samples from the poor ones. The difference between the indices for good and poor samples is slightly larger produced by the cluster method. 11 However, without the samples evaluated by human experts, the goodness of these results is still questionable. This comparison will be left to the next phase of the project.
Resumo:
Technology scaling has proceeded into dimensions in which the reliability of manufactured devices is becoming endangered. The reliability decrease is a consequence of physical limitations, relative increase of variations, and decreasing noise margins, among others. A promising solution for bringing the reliability of circuits back to a desired level is the use of design methods which introduce tolerance against possible faults in an integrated circuit. This thesis studies and presents fault tolerance methods for network-onchip (NoC) which is a design paradigm targeted for very large systems-onchip. In a NoC resources, such as processors and memories, are connected to a communication network; comparable to the Internet. Fault tolerance in such a system can be achieved at many abstraction levels. The thesis studies the origin of faults in modern technologies and explains the classification to transient, intermittent and permanent faults. A survey of fault tolerance methods is presented to demonstrate the diversity of available methods. Networks-on-chip are approached by exploring their main design choices: the selection of a topology, routing protocol, and flow control method. Fault tolerance methods for NoCs are studied at different layers of the OSI reference model. The data link layer provides a reliable communication link over a physical channel. Error control coding is an efficient fault tolerance method especially against transient faults at this abstraction level. Error control coding methods suitable for on-chip communication are studied and their implementations presented. Error control coding loses its effectiveness in the presence of intermittent and permanent faults. Therefore, other solutions against them are presented. The introduction of spare wires and split transmissions are shown to provide good tolerance against intermittent and permanent errors and their combination to error control coding is illustrated. At the network layer positioned above the data link layer, fault tolerance can be achieved with the design of fault tolerant network topologies and routing algorithms. Both of these approaches are presented in the thesis together with realizations in the both categories. The thesis concludes that an optimal fault tolerance solution contains carefully co-designed elements from different abstraction levels
Resumo:
Vesivoimalla on merkittävä rooli pohjoismaisessa sähköntuotantojärjestelmässä. Spot-markkinoille tarjottavan vesivoiman hinta riippuu vaihtoehtoisen tuotannon hinnasta ja odotetusta vesivoimantuottajien käytettävissä olevasta veteen sitoutuneen potentiaalienergian määrästä. Hydrologisella tilanteella tarkoitetaan tässä tämän potentiaalienergian poikkeamaa normaalitasostaan. Viime vuosina tuulivoimatuotanto pohjoismaisella sähkömarkkina-alueella on kasvanut voimakkaasti, ja on tullut aiheelliseksi tarkastella, millaisia vaikutuksia tällä on vesivoimantuottajien toimintaan. Työssä määritellään vesivoimalle vaihtoehtoisen sähköntuotannon tuotantokustannus, joka pitkällä aikavälillä toimii vertailutasona, jonka perusteella vesivoimantuottajat määrittävät markkinoilla tarjontahinnan tuotannolleen. Tarkastellaan, kuinka hydrologisen tilanteen ja vaihtoehtoisen tuotannon tuotantokustannusten muutokset vaikuttavat vesiarvoon, joka on hinta, jolla hintariippuvaista eli säätyvää vesivoimaa tarjotaan spot-markkinoille. Todetaan, että hydrologisen tilanteen vahvistuminen ja vaihtoehtoisen tuotantokustannuksen aleneminen alentavat vesiarvoja. Todetaan lisäksi, että tuulivoima vaikuttaa sähkön hinnanmuodostukseen markkinoilla samankaltaisesti kuin hintariippumaton vesivoimatuotanto. Esitetään aikasarjamalli vesivoimatuotannon hintariippuvuuden mallintamiseksi. Vertaillaan vesivoimatuottajien toimintaa kahdella vesivoimatuotantoa sisältävällä hinta-alueella, joista toisella tuulivoimatuotanto on kasvanut voimakkaammin kuin toisella. Havaitaan, että molemmilla hinta-alueilla hydrologisen tilanteen vahvistuminen on alentanut ja heikkeneminen nostanut vesiarvoja. Lisäksi havaitaan, että alueella, jonka tuulivoimatuotanto on kasvanut enemmän, vesiarvot ovat laskeneet suhteessa alueen, jolla tuulivoimatuotanto on kasvanut vähemmän, vesiarvoihin. Tuulivoiman voidaan todeta syrjäyttäneen markkinoilta tuotantokustannuksiltaan kalliimpaa tuotantoa.
Resumo:
Abstract