Offset-print mottling measurement using machine vision

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.

Kuivatusmenetelmien vaikutus heatset offset- ja syväpainetun SC-paperin laatuun

Työssä tutkittiin heatset offset- ja syväpainetun SC-paperin painojäljen laatua, kun koepaperikoneella valmistetun SC-paperin valmistuksessa käytettiin eri kuivatus-menetelmiä. Erityisesti kiinnostus kohdistui eri kuiva-ainepitoisuuksissa käytetyn ilmakuivatuksen aiheuttamiin painojäljen laatuvaikutuksiin. Painojäljen lisäksi työssä tarkasteltiin pohjapaperin ominaisuuksia kuivatuksen jakalanteroinnin jälkeen. Perinteisen sylinterikuivatuksen kuivatuskapasiteettia voidaan nostaa kuivattamalla paperia kuuman ilman avulla, jolloin paperin haihdutusnopeus nousee yli viisinkertaiseksi sylinterikuivatukseenverrattuna. Ilmakuivatus voidaan sijoittaa välittömästä kuivatusosan alkuun ennen ensimmäistä kuivatussylinteriä tai korkeampaan kuiva-ainepitoisuuteen sylinterikuivatuksen keskelle. Kuivattua paperia tarkasteltaessa kuuman ilman avulla kuivatun paperin ominaisuudet poikkesivat huokoisuuden ja öljynabsorption suhteen sylinterikuivatusta paperista sekä heatset offset- että syväpainopaperilla. Kalanterointi tasoitti koepisteiden välisiä muutoksia. Kalanteroidusta paperista havaittiin, että ilmakuivatuksen sijoittuminen välittömästi puristimen jälkeen kasvatti paperin molempien pintojen opasiteettia. Vastaavasti paperin tiheys kasvoi, kun paperia kuivattiin kuumalla ilmalla sekä ennen sylinterikuivatusta että sylinterikuivatuksen keskellä. Yhteistä ilmakuivatuksen käytölle kaikissa koepisteissä oli paperin huokoisuuden pieneneminen. Heatset offsetpainoprosessissa käytettävä kostutusvesi asettaa paperin kuitu-karhenemiselle vaatimuksia. Tutkimuksessa havaittiin, että puristimen jälkeen sijoitettu ilmakuivatus pienensi paperin taipumusta karhentua painoprosessissa. Muiden ominaisuuksien osalta paperin kuivatus kuuman ilman avulla yhdessä sylinterikuivatuksen kanssa ei jättänyt paperiin sellaisia jälkiä, jotka näkyisivät heatset offset- ja syväpainetun SC-paperin painojäljessä verrattuna kokonaan yksiviira-vientisesti sylinterikuivattuun paperiin.

Big band -sovitus kappaleesta "(Surrounded by) Zip-Zip" : Sovituksen analysoiminen puhallinsektioiden näkökulmasta

Opinnäytetyö käsittelee big bandia sekä sille sovittamista. Keskityn tarkastelemaan ennen kaikkea 1930-40-lukujen musiikillista murrosta, jolloin syntyi uusi tapa käsitellä useasti suurimpien orkestereiden kokoonpanoon kuuluneita puhaltimia. Tuona ajanjaksona orkestereiden puhallinryhmistä sekä komppisoittimista alettiin yleisesti muodostaa sektioita. Tämä kokoonpano sai nimekseen ”big band”. Opinnäytetyön tavoitteena oli syventää tietojani big bandin puhallinsektioiden toiminnasta sekä niiden yleisimmistä tehtävistä. Tehtäviä selventääkseni tein big band -sovituksen omasta kappaleestani, missä peilasin 1930-40-luvuilla yleistynyttä tyyliä sovittaa. Sovitustyön valmistuminen pohjautui kolmeen seikkaan: historian tuntemus, sovitussuunnitelman teko sekä musiikin teorian tuntemus. Historian tuntemus loi pohjan sovitussuunnitelmalle, minkä avulla loin kehykset sovitustyön tekemiselle. Sovituksen tekninen suoritus sekä valmistuminen pohjautuivat musiikin teorian ymmärtämiseen sekä kokemukseeni sovittajana. Sovitukseni analyysi-osiossa käyn sovituksen läpi osa kerrallaan, selventäen kuinka puhallinsektiot kussakin osassa toimivat. Opinnäytetyön suunnittelu sekä tiukka rajaus eivät poissulkeneet täysin aiheen moniulotteisuutta. Pelkkiin puhallinsektioihin keskittyminen aiheutti ongelmallisia tilanteita, jotka vaativat suurien kompromissien tekemistä. Muun muassa teorian ja reharmonisoinnin syvempi analysoiminen tässä jää tekemättä. Sovituksellisten sekä soinnullisien ratkaisuiden olemassaolo vaatisi yleensä rinnalleen syvempää perustelua. Näin varsinkin nyt, kun ratkaisut harmoniassa ovat aika ajoin jopa radikaaleja. Tulin kuitenkin siihen päätelmään, että kaikki tekstissä ilmenevä tieto mikä ei koskisi puhallinsektioiden käyttäytymistä olisi irrelevanttia. Lopputuloksen oli tarkoitus olla jäsennelty esittely siitä, mitä big bandin puhallinsektiot ovat ja tekevät. Käyn opinnäytteessäni lyhyesti läpi myös sovitukseni esikuvat. Tämä lyhyt historia-osuus kertoo tiivistetysti mistä ajalta mallintamani sovitustyyli on peräisin ja ketkä ovat edesauttaneet sen yleistymisessä. Historia osuus toimii mainiosti suppeana avainsanastona aiheesta enemmän kiinnostuneelle.

Influence of plasma modification on surface properties and offset printability of coated paper

The properties of the paper surface play a crucial role in ensuring suitable quality and runnability in various converting and finishing operations, such as printing. Plasma surface modification makes it possible to modify the surface chemistry of paper without altering the bulk material properties. This also makes it possible to investigate the role of the surface chemistry alone on printability without influencing the porous structure of the pigment-coated paper. Since the porous structure of a pigment coating controls both ink setting and optical properties, surface chemical changes created by a plasma modification have a potential to decouple these two effects and to permit a better optimization of them both. The aim of this work was to understand the effects of plasma surface modification on paper properties, and how it influences printability in the sheet-fed offset process. The objective was to broaden the fundamental understanding of the role of surface chemistry on offset printing. The effects of changing the hydrophilicity/ hydrophobicity and the surface chemical composition by plasma activation and plasma coatings on the properties of coated paper and on ink-paper interactions as well as on sheet-fed offset print quality were investigated. In addition, the durability of the plasma surface modification was studied. Nowadays, a typical sheet-fed offset press also contains units for surface finishing, for example UVvarnishing. The role of the surface chemistry on the UV-varnish absorption into highly permeable and porous pigment-coated paper was also investigated. With plasma activation it was possible to increase the surface energy and hydrophilicity of paper. Both polar and dispersion interactions were found to increase, although the change was greater in the polar interactions due to induced oxygen molecular groups. The results indicated that plasma activation takes place particularly in high molecular weight components such as the dispersion chemicals used to stabilize the pigment and latex particles. Surface composition, such as pigment and binder type, was found to influence the response to the plasma activation. The general trend was that pilot-scale treatment modified the surface chemistry without altering the physical coating structure, whereas excessive laboratory-scale treatment increased the surface roughness and reduced the surface strength, which led to micro-picking in printing. It was shown that pilot-scale plasma activation in combination with appropriate ink oils makes it possible to adjust the ink-setting rate. The ink-setting rate decreased with linseed-oil-based inks, probably due to increased acid-base interactions between the polar groups in the oil and the plasma-treated paper surface. With mineral-oil-based inks, the ink setting accelerated due to plasma activation. Hydrophobic plasma coatings were able to reduce or even prevent the absorption of dampening water into pigmentcoated paper, even when the dampening water was applied under the influence of nip pressure. A uniform hydrophobic plasma coating with sufficient chemical affinity with ink gave an improved print quality in terms of higher print density and lower print mottle. It was also shown that a fluorocarbon plasma coating reduced the free wetting of the UV-varnish into the highly permeable and porous pigment coating. However, when the UV-varnish was applied under the influence of nip pressure, which leads to forced wetting, the role of the surface chemical composition seems to be much less. A decay in surface energy and wettability occurred during the first weeks of storage after plasma activation, after which it leveled off. However, the oxygen/carbon elemental ratio did not decrease as a function of time, indicating that ageing could be caused by a re-orientation of polar groups or by a contamination of the surface. The plasma coatings appeared to be more stable when the hydrophobicity was higher, probably due to fewer interactions with oxygen and water vapor in the air.

Den talande bokens poetik : en studie med fokus på olika unga vuxnas reception av tre fiktiva texter inlästa på band

The purpose of the research project The poetics of the talking book is to contribute to the knowledge about patterns of understanding in young adults’ reception of fiction, which they listened to through audio books. The problem explored was: How do different groups of listeners receive fictive text presented as a talking book with variations regarding use of voice, engagement and sound effects? The problem formulation rendered four specific research questions: 1. What patterns can be identified in the listeners’ answers regarding story structure and cognitive content in a comparative perspective comprising different reading styles in the taped versions of the text? 2. What patterns of understanding in interpretative reading can be identified in different listeners? 3. Which thoughts do the listeners have about what the talking book should sound like? 4. What affordances for young adults with the functional disability of mild mental retardation can be made visible through guided literature conversations? The theoretical frame of reference was formed by text–reader-oriented literary theory, psychological schema theory, and research regarding voice quality and communication. The project was carried out in two steps. The first phase was to produce the audio books with two variations of reading practice of three short stories with an existential theme in each text. The second step comprised interviewing of 32 young adults (a special group with a reading handicap in form of mild mental retardation, and a reference group with no handicap). The interviews formed as literary conversation were carried out three times during one year. The phenomenological-hermeneutic approach focused on the life worlds of the participants as meaning seeking beings. The analysis was carried out using method triangulation, mainly using phenomenological meaning concentration. The double hermeneutics in use when interpreting the interpretations of the participants revealed a capacity for aesthetic reading of fiction in the special group as well as in the reference group. The aesthetic qualities were found sufficient in all variations of reading by the professional readers of the audio book they listened to. The young adults also could describe how they wanted the audio book to sound: just as if you were reading yourself. A model describing the analytical steps and concepts in use was a result that can serve as an outline of a poetics for the talking book. Unexpected research results were how important the guided literary conversation turned out to be in order to realise the affordances given by the texts regarding exploration of existential themes in the young adults’ life worlds. Thus the result of the research project can be positioned as a piece of emancipatory research stressing the importance of including this group of young adults in the society’s conversation about culture and meaning.

Studies in offset ink setting

The offset printing process is complex and involves the meeting of two essentially complex materials, printing ink and paper, upon which the final product is formed. It can therefore be expected that a multitude of chemical and physical interactions and mechanisms take place at the ink-paper interface. Interactions between ink and paper are of interest to both the papermakers and ink producers, as they wish to achieve better quality in the final product. The objective of this work is to clarify the combined influence of paper coating structure, printing ink and fountain solution on ink setting and the problems related to ink setting. A further aim is to identify the mechanisms that influence ink setting problems, and to be able to counteract them by changing properties of the coating layer or by changing the properties of the ink. The work carried out for this thesis included use of many techniques ranging from standard paper and printability tests to advanced optical techniques for detection of ink filaments during ink levelling. Modern imaging methods were applied for assessment of ink filament remain sizes and distribution of ink components inside pigment coating layers. Gravimetric filtration method and assessment of print rub using Ink-Surface-Interaction-Tester (ISIT) were utilized to study the influence of ink properties on ink setting. The chemical interactions were observed with the help of modified thin layer chromatography and contact angle measurements using both conventional and high speed imaging. The results of the papers in this thesis link the press operational parameters to filament sizes and show the influence of these parameters to filament size distribution. The relative importance between the press operation parameters was shown to vary. The size distribution of filaments is important in predicting the ink setting behaviour, which was highlighted by the dynamic gloss and ink setting studies. Prediction of ink setting behaviour was also further improved by use of separate permeability factors for different ink types in connection to filtration equations. The roles of ink components were studied in connection to ink absorption and mechanism of print rub. Total solids content and ratio of linseed oil to mineral oil were found to determine the degree of print rub on coated papers. Wax addition improved print rub resistance, but would not decrease print rub as much as lowering the total solids content in the ink. Linseed oil was shown to absorb into pigment coating pores by mechanism of adsorption to pore walls, which highlights the need for sufficient pore surface area for improved chromatographic separation of ink components. These results should help press operators, suppliers of printing presses, papermakers and suppliers to papermakers, to better understand the material and operating conditions of the press as it relates to various print quality issues. Even though paper is in competition with electronic media, high quality printed products are still in demand. The results should provide useful information for this segment of the industry.

Das Lebenswerk der Sibirienforscherin Zoja Sokolova in einem Band

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