Critical flux and fouling in ultrafiltration of proteins

In this thesis different parameters influencing critical flux in protein ultrafiltration and membrane foul-ing were studied. Short reviews of proteins, cross-flow ultrafiltration, flux decline and criticalflux and the basic theory of Partial Least Square analysis (PLS) are given at the beginning. The experiments were mainly performed using dilute solutions of globular proteins, commercial polymeric membranes and laboratory scale apparatuses. Fouling was studied by flux, streaming potential and FTIR-ATR measurements. Critical flux was evaluated by different kinds of stepwise procedures and by both con-stant pressure and constant flux methods. The critical flux was affected by transmembrane pressure, flow velocity, protein concentration, mem-brane hydrophobicity and protein and membrane charges. Generally, the lowest critical fluxes were obtained at the isoelectric points of the protein and the highest in the presence of electrostatic repulsion between the membrane surface and the protein molecules. In the laminar flow regime the critical flux increased with flow velocity, but not any more above this region. An increase in concentration de-creased the critical flux. Hydrophobic membranes showed fouling in all charge conditionsand, furthermore, especially at the beginning of the experiment even at very low transmembrane pressures. Fouling of these membranes was thought to be due to protein adsorption by hydrophobic interactions. The hydrophilic membranes used suffered more from reversible fouling and concentration polarisation than from irreversible foul-ing. They became fouled at higher transmembrane pressures becauseof pore blocking. In this thesis some new aspects on critical flux are presented that are important for ultrafiltration and fractionation of proteins.

Short-term forecasting of power demand in the Nord Pool market

Sähkönkulutuksen lyhyen aikavälin ennustamista on tutkittu jo pitkään. Pohjoismaisien sähkömarkkinoiden vapautuminen on vaikuttanut sähkönkulutuksen ennustamiseen. Aluksi työssä perehdyttiin aiheeseen liittyvään kirjallisuuteen. Sähkönkulutuksen käyttäytymistä tutkittiin eri aikoina. Lämpötila tilastojen käyttökelpoisuutta arvioitiin sähkönkulutusennustetta ajatellen. Kulutus ennusteet tehtiin tunneittain ja ennustejaksona käytettiin yhtä viikkoa. Työssä tutkittiin sähkönkulutuksen- ja lämpötiladatan saatavuutta ja laatua Nord Poolin markkina-alueelta. Syötettävien tietojen ominaisuudet vaikuttavat tunnittaiseen sähkönkulutuksen ennustamiseen. Sähkönkulutuksen ennustamista varten mallinnettiin kaksi lähestymistapaa. Testattavina malleina käytettiin regressiomallia ja autoregressiivistä mallia (autoregressive model, ARX). Mallien parametrit estimoitiin pienimmän neliösumman menetelmällä. Tulokset osoittavat että kulutus- ja lämpötiladata on tarkastettava jälkikäteen koska reaaliaikaisen syötetietojen laatu on huonoa. Lämpötila vaikuttaa kulutukseen talvella, mutta se voidaan jättää huomiotta kesäkaudella. Regressiomalli on vakaampi kuin ARX malli. Regressiomallin virhetermi voidaan mallintaa aikasarjamallia hyväksikäyttäen.

Reaction Kinetics and Viscosity Modelling in the Fusion Syntheses of Ca- and Ca/Mg-resinates

Rosin is a natural product from pine forests and it is used as a raw material in resinate syntheses. Resinates are polyvalent metal salts of rosin acids and especially Ca- and Ca/Mg- resinates find wide application in the printing ink industry. In this thesis, analytical methods were applied to increase general knowledge of resinate chemistry and the reaction kinetics was studied in order to model the non linear solution viscosity increase during resinate syntheses by the fusion method. Solution viscosity in toluene is an important quality factor for resinates to be used in printing inks. The concept of critical resinate concentration, c crit, was introduced to define an abrupt change in viscosity dependence on resinate concentration in the solution. The concept was then used to explain the non-inear solution viscosity increase during resinate syntheses. A semi empirical model with two estimated parameters was derived for the viscosity increase on the basis of apparent reaction kinetics. The model was used to control the viscosity and to predict the total reaction time of the resinate process. The kinetic data from the complex reaction media was obtained by acid value titration and by FTIR spectroscopic analyses using a conventional calibration method to measure the resinate concentration and the concentration of free rosin acids. A multivariate calibration method was successfully applied to make partial least square (PLS) models for monitoring acid value and solution viscosity in both mid-infrared (MIR) and near infrared (NIR) regions during the syntheses. The calibration models can be used for on line resinate process monitoring. In kinetic studies, two main reaction steps were observed during the syntheses. First a fast irreversible resination reaction occurs at 235 °C and then a slow thermal decarboxylation of rosin acids starts to take place at 265 °C. Rosin oil is formed during the decarboxylation reaction step causing significant mass loss as the rosin oil evaporates from the system while the viscosity increases to the target level. The mass balance of the syntheses was determined based on the resinate concentration increase during the decarboxylation reaction step. A mechanistic study of the decarboxylation reaction was based on the observation that resinate molecules are partly solvated by rosin acids during the syntheses. Different decarboxylation mechanisms were proposed for the free and solvating rosin acids. The deduced kinetic model supported the analytical data of the syntheses in a wide resinate concentration region, over a wide range of viscosity values and at different reaction temperatures. In addition, the application of the kinetic model to the modified resinate syntheses gave a good fit. A novel synthesis method with the addition of decarboxylated rosin (i.e. rosin oil) to the reaction mixture was introduced. The conversion of rosin acid to resinate was increased to the level necessary to obtain the target viscosity for the product at 235 °C. Due to a lower reaction temperature than in traditional fusion synthesis at 265 °C, thermal decarboxylation is avoided. As a consequence, the mass yield of the resinate syntheses can be increased from ca. 70% to almost 100% by recycling the added rosin oil.

Järeiden puutuotteiden erikoiskuivaus

Tutkimuksessa selvitettiin kuumakuivauksen vaikutusta hirsiraaka-aineen ominaisuuksiin, käyttökelpoisia kuivauskaavoja sekä lämpötilatasoja. Kokeissa kuivattiin kuorittuja pyöreitä mäntytukkeja 130-180° C:n maksimilämpötilassa, sekä pelkaksi sahattuja hirsiaihioita 115-140° C:n maksimilämpötilassa. Kuivauksissa pyrittiin mahdollisimman lyhyeen aikaan laadun siitä kuitenkaan kärsimättä. Laadussa kiinnitettiin erityisesti huomiota sisä- ja pintahalkeamiin sekä värimuutoksiin. Korkeita lämpötiloja käytettäessä kuivausaika oli huomattavasti nopeampi kuin lämminilmakuivauksessa. Koekuivaukset kestivät 1-4 vuorokautta, kun vastaavaa puutavaraan lämminilmakuivaus kestää 7-20 vuorokautta. Korkeimmilla lämpötiloilla suoritetuissa kokeissa koekappaleisiin muodostui paljon pieniä halkeamia kun taas alhaisemmilla lämpötiloilla halkeamien kappalemäärä väheni, mutta lähes joka kappaleessa oli vähintään yksi suuri (yli 5 mm leveä) halkeama. Sisähalkeamien määrä oli pyöreillä tukeilla suoritetuissa kokeissa kohtuullisen pieni. Pelkaksi sahatuilla aihioilla sitä vastoin sisähalkeamien määrä oli huomattavasti suurempi. Vain 100 mm x 175 mm aihioilla onnistuttiin yhdessä kuivauksessa pitämään sisähalkeaminen pienenä. Kuumakuivaus aiheuttaa väistämättä värimuutoksia puuhun. Mitä korkeammilla lämpötiloilla ja pidemmillä kaavoilla kuivataan sitä enemmän väri tummenee. Värin vaikutus lopputuotteessa riippuu kuitenkin käyttökohteesta ja asiakkaan mieltymyksistä. Tutkimuksen perusteella varsinkin pyöreiden tukkien kuumakuivaus näyttää onnistuvan laadul-lisesti hyvin ja huomattavasti lämminilmakuivausta nopeammin. Pelkaksi sahattujen hirsiaihioiden kuivauksessa prosessin hallinta havaittiin vaikeaksi ja toimivien kaavojen kehittäminen vaatii jatkotutkimuksia.

Long-term impacts of forest harvesting related soil disturbance on log product yields and economic potential in a New Zealand forest

Abstract

The attractiveness of the work is affected when production of handcrafted log houses moves indoors

Abstract

GPS-paikkatiedonliittäminen matkapuhelinpalveluihin

2000-luvun vaihteessa paikkatietoa hyödyntävistä matkapuhelinpalveluista odotettiin muodostuvan eräs merkittävimmistä kilpailuvalteista eri matkapuhelinoperaattoreiden välillä. Kiinnostusta paikkatietoa hyödyntäviin palveluihin lisäsi kaupallisten sovellusten lisäksi Yhdysvaltojen liittovaltioiden liikenneministeriön säätämä laki, joka velvoittaa paikantamaan yleiseen hätänumeroon soitetut puhelut. Erityisesti laite- ja verkkotoimittajat odottivat tämänluovan heille uusia markkinoita. Markkinoille tuli useita kilpailevia menetelmiä, joilla matkapuhelimia voitiin paikantaa. Suurin osa näistä menetelmistä hyödynsi GSM-verkon signalointia paikannuksen tekemiseen. Samaan aikaan kohonnut matkapuhelinten suorituskyky mahdollisti GPS-vastaanottimien integroinnin matkapuhelimiin ja ensimmäiset tällaiset matkapuhelimet ilmestyivät markkinoille. Matkapuhelinten paikantamiseen liittyvä standardointi on melko hajanaista. ETSI on standardoinut joukon erilaisia menetelmiä, joilla matkapuhelin paikkatieto voidaan selvittää. Nämä standardit eivät kuitenkaan määrittele sitä, kuinka paikkatieto siirretään sitä hyödyntävien palveluiden käyttöön. Paikkatiedonsiirtämiseen ja esittämiseen liittyvässä standardoinnissa eri laite- ja ohjelmistovalmistajat ovat tehneet liittoutumia keskenään ja esitelleet keskenään kilpailevia standardeja ja suosituksia. Tälläkään osa-alueella mikään liittoutuma ei ole saavuttanut määräävää markkina-asemaa. Tässä työssä suunniteltiin ja toteutettiin järjestelmä, jonka avulla voidaan paikantaa sellaisia GSM-päätelaitteita, joihin on integroitu GPS-vastaanotin. Toteutettu järjestelmä liitettiin uudeksi paikannusmenetelmäksi solupaikannuksen rinnalle Sonera Pointer paikannusjärjestelmään. Työn aikana testattiin joukko markkinoilla olleita GSM-puhelimia, joihin oli integroitu GPS-vastaanotin. Matkapuhelinten testauksessa erityinen huomio kiinnittyi siihen, kuinka GPS-paikkatieto saadaan siirrettyä matkapuhelimesta verkossa sijaitsevien sovellusten käyttöön. Toteutetun järjestelmän suunnittelussa täkein lähtökohta oli järjestelmän joustavuus. Standardien hajanaisuus ja osittainen puuttuminen aiheuttivat sen, että järjestelmästä oli tehtävä mahdollisimman helposti laajennettava. Toinen merkittävä suunnitteluun vaikuttanut tekijä oli operaattoririippumattomuus, koska Sonera Pointer järjestelmää oli tarkoitus myydä myös muille matkapuhelinoperaattoreille.

Improving Dynamic Characteristics of Open-loop Controlled Log Crane

The improvement of the dynamics of flexible manipulators like log cranes often requires advanced control methods. This thesis discusses the vibration problems in the cranes used in commercial forestry machines. Two control methods, adaptive filtering and semi-active damping, are presented. The adaptive filter uses a part of the lowest natural frequency of the crane as a filtering frequency. The payload estimation algorithm, filtering of control signal and algorithm for calculation of the lowest natural frequency of the crane are presented. The semi-active damping method is basedon pressure feedback. The pressure vibration, scaled with suitable gain, is added to the control signal of the valve of the lift cylinder to suppress vibrations. The adaptive filter cuts off high frequency impulses coming from the operatorand semi-active damping suppresses the crane?s oscillation, which is often caused by some external disturbance. In field tests performed on the crane, a correctly tuned (25 % tuning) adaptive filter reduced pressure vibration by 14-17 % and semi-active damping correspondingly by 21-43%. Applying of these methods require auxiliary transducers, installed in specific points in the crane, and electronically controlled directional control valves.

GPS-signal Source Based on Direct Digital Synthesis

This thesis presents the design and implementation of a GPS-signal source suitable for receiver measurements. The developed signal source is based on direct digital synthesis which generates the intermediate frequency. The intermediate frequency is transfered to the final frequency with the aid of an Inphase/Quadrature modulator. The modulating GPS-data was generated with MATLAB. The signal source was duplicated to form a multi channel source. It was shown that, GPS-signals ment for civil navigation are easy to generate in the laboratory. The hardware does not need to be technically advanced if navigation with high level of accuracy is not needed. It was also shown that, the Inphase/Quadrature modulator can function as a single side band upconverter even with a high intermediate frequency. This concept reduces the demands required for output filtering.

Conservation Laws in Cellular Automata

Conservation laws in physics are numerical invariants of the dynamics of a system. In cellular automata (CA), a similar concept has already been defined and studied. To each local pattern of cell states a real value is associated, interpreted as the “energy” (or “mass”, or . . . ) of that pattern.The overall “energy” of a configuration is simply the sum of the energy of the local patterns appearing on different positions in the configuration. We have a conservation law for that energy, if the total energy of each configuration remains constant during the evolution of the CA. For a given conservation law, it is desirable to find microscopic explanations for the dynamics of the conserved energy in terms of flows of energy from one region toward another. Often, it happens that the energy values are from non-negative integers, and are interpreted as the number of “particles” distributed on a configuration. In such cases, it is conjectured that one can always provide a microscopic explanation for the conservation laws by prescribing rules for the local movement of the particles. The onedimensional case has already been solved by Fuk´s and Pivato. We extend this to two-dimensional cellular automata with radius-0,5 neighborhood on the square lattice. We then consider conservation laws in which the energy values are chosen from a commutative group or semigroup. In this case, the class of all conservation laws for a CA form a partially ordered hierarchy. We study the structure of this hierarchy and prove some basic facts about it. Although the local properties of this hierarchy (at least in the group-valued case) are tractable, its global properties turn out to be algorithmically inaccessible. In particular, we prove that it is undecidable whether this hierarchy is trivial (i.e., if the CA has any non-trivial conservation law at all) or unbounded. We point out some interconnections between the structure of this hierarchy and the dynamical properties of the CA. We show that positively expansive CA do not have non-trivial conservation laws. We also investigate a curious relationship between conservation laws and invariant Gibbs measures in reversible and surjective CA. Gibbs measures are known to coincide with the equilibrium states of a lattice system defined in terms of a Hamiltonian. For reversible cellular automata, each conserved quantity may play the role of a Hamiltonian, and provides a Gibbs measure (or a set of Gibbs measures, in case of phase multiplicity) that is invariant. Conversely, every invariant Gibbs measure provides a conservation law for the CA. For surjective CA, the former statement also follows (in a slightly different form) from the variational characterization of the Gibbs measures. For one-dimensional surjective CA, we show that each invariant Gibbs measure provides a conservation law. We also prove that surjective CA almost surely preserve the average information content per cell with respect to any probability measure.

Trolley R&D project for a small portal log yard crane

This master’s thesis was done for Andritz Inc. Atlanta Georgia. The purpose of the thesis was to develop a new trolley for a small portal log yard crane. In the beginning of the thesis the basic principles of the systematic design processes have been described, along which the design work of the trolley has proceeded. The second literature part consists of the design and dimensioning of the welded steel structures under fatigue loading. The design work of the trolley consists of the engineering and the selection of the mechanical components and the design of the load carrying structure for the trolley. The realization of the steel structure of the trolley is based on the fatigue and static dimensioning. The fatigue dimensioning is grounded in the life expectations estimated for the trolley and the static dimensioning is based on the CMAA guidelines. The computer aided element method was utilized in the design of the steel structure. The effective notch method and the hot spot method were used in the fatigue calculations. The trolley structure was carried out by using the sheet metal parts in order to manufacture the structure as effective and low cost way as possible. The corner stone of the dimensioning of the trolley structure was the utilization of the open profiles made of welded or cold formed sheet metals, which provide better weldability, weld inspection, access for repairs and corrosion protection. As a last part of the thesis a new trolley traveling system was developed. The distribution of the wheel loads of the trolley bogies on the main girder was also studied, which led to an innovative suspension arrangement between the trolley leg and the bogie. The new bogie solution increases the service life of the main girder of the crane and improves the stability of the bogies. The outcome of the thesis is an excellent trolley structure from the weight and the service life point of view.