Kolme lähestymistapaa kuntienvälisen muuttoliikkeen taloustieteeseen

Artikkeli perustuu tekijän kunnallistalouden väitöskirjaan, joka tarkastettiin Tampereen yliopistossa 27.10.2006.

Materiaalitoimintojen kehittäminen kokoonpano-osastolla

Työn tavoitteena oli yhtenäisen toimintamallin luominen kohdeyrityksen materiaalitoiminnoille tuotannon kokoonpano-osastolla ja kokoonpanoa palvelevissa varastoissa. Toimintamallin tuli kattaa nimikkeiden siirrot ja siirtoihin liittyvät toimet toiminnanohjausjärjestelmässä. Lisäksi toimintamallin tuli vähentää saldovirheitä ja niistä johtuvia osapuutteita ja inventaarioepäselvyyksiä. Nykytilan kartoituksella yksilöitiin oleellisimmat kehityskohteet saldovirheiden eliminoimiseksi. Myös yrityksen lean-implementoinnin vaatimukset materiaalitoimintojen luotettavuudelle oli huomioitava. Kehityskohteiden tehostustoimista luotiin materiaalitoimintojen malli, joka yhtenäistää käytäntöjä ja vähentää operatiivisia saldojen hallinnan haasteita.

Suitability of foam coating on application of thin liquid films

This work aimed to find out the suitability of foam as medium in application of thin liquid films. This consists of research over phenomena related to foam physics and behaviour. Solutions and mixtures to be foamed, foaming agents, foam generation and application methods were evaluated. Over the evaluated solutions and mixtures coating paste and CMC did not foam well. Latex and PVA solutions were foamable and the best solution for foam use was starch. PVA and casein can be used as foaming agents, but the best results were achieved with sodium dodecyl sulphate (SDS). SDS works well with starch solutions producing fine and stable foam. Foaming was done with simple mixers where pressurized air was fed to the solution. The foaming works fine when enough shear force is used together with sufficient foaming agent concentration. Foam application with curtain, rod and cylinder methods with a gap between the application device and paper were not usable because of high coating amount. Coating amounts were smallest with the blade method which achieved 0.9 g/m2 starch layer. Although some strength decrease was expected because of the foaming agent, it dit not have significant effect. The targeted coating amount of 0.5 g/m2 was not achieved due to the limitations with the methods. More precise foam application methods are needed. Continuous foam generation and feed to the paper surface with controllable device such as application teeth could improve the results.

Supersaturation-controlled crystallization

Identification of product requirements and quality, together with the management of production are key issues in chemical engineering. Quality control of crystalline products is part of the quality of many industrially manufactured products like paper, paintings, medicines and fertilizers. In most crystallization cases, quality is described with the size, polymorph, shape and purity of the crystal. The chemical composition, hydrodynamics and driving force, together with the operating temperature are in a key position when the properties of a crystalline product are controlled with the crystallization process. This study concentrates on managing the identified properties of a crystalline product with the control of a driving force. The controlling of the driving force can be based on the change of solubility or the change of concentration. Solubility can be changed with temperature, pressure and an antisolvent. The concentration of crystallizing compound, the solute can be changed with the evaporation of the solvent and with the addition of a reagent. The present study focuses on reagent addition and temperature change as methods of changing the level of the driving force. Three control structures for direct control of supersaturation are built, one for cooling crystallization and two for reactive crystallization. Closed loop feedback control structures are based on the measurement of the solute concentration with attenuated total reflection - Fourier transform infrared spectrometer. The details of the reagent feed are analyzed with experimental studies and with results of computational fluid dynamic simulations of the inert particle pulse in the premixer and inert particle injection to the mixing tank. Nucleation in conditions of controlled reactive crystallization is analyzed with Nielsen’s equation of homogeneous nucleation. The resulting control systems, based on regulation of supersaturation, can be used to produce the desired polymorph of an organic product. The polymorph composition of product crystals is controlled repeatably with the decision of a set value of supersaturation level.

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