No description available.

This degree project illustrates newsprint and waterless offset. A new news press was introduced at Drupa-00, Cortina from KBA, which is the first news press dedicated the waterless technique. With actual statistics from the company in question an investigation was made whether their production fits this press. It came out in the investigation that the production of the company, from statistics, fits this press very good. A table was made where different timeschedules were accounted for the new press, with semi- and full automatic plate changing for present and to be added papers. The waterless technology is compared to conventional offset with the difference that the plate is based on a sort of laminatetechnology. Like conventional plates this plate has a base made of aluminium. Lightsensitive photopolymer isunited as a layer or coat on top of the aluminium and a 2µm thin oleophobic siliconlayer is applied on top of the photopolymer. Considering the print, the waterless method has a higher qualitygrade than conventional offset. No water is emulsifiedin the ink, and therefore the printed dot gets a higher density. The loss of dampening solution and higher tack of the ink gives sharper dots. This makes the colourspace bigger why a greater range of colours can be printed. The loss of dampening solution gives a more stable dotgain, which contributes to that a higher screen can be used. The disadvantage is that the plate can't do as many rotations as the conventional plate. A waterless plate makes around 100 000-500 000 rotations before it needs to be removed owing to type- and manufacturer of the plate. The plate is also slightly more sensitive and expensive than conventional plates, around 1,4 - 1,7 × aluminium printing plates. A waterless system can be installed in a conventional printing press by degrees and when large editions are being printed a cooler needs to be installed in the oscillationrollers of the press, since an increase in temperature can make the oleophobic parts of the plate oleophilic. The Cortina is however equipped with a temperature controlsystem at the beginning. To avoid picking, caused by the tacky ink, a blanket with a high “quick release” should be used.

No description available.

The present thesis describes an experimental and theoretical investigation of the flow field and scour action of an offset jet. The hydraulic characteristics of the offset jet and the resulting scour developed in the bed were investigated in the laboratory. Tests were carried out using a fixed bed and a single offset ratio (height of jet above bed / jet thickness). Three flow rates were used. Velocity measurements in two directions, especially in the recirculating zone, were of help in understanding the flow field and in providing the necessary data for comparison with the theoretical results. The development of scour, on a uniform sand, was monitored at set time intervals, in most cases until the asymptotic state was reached. A new effective and simple method for measuring the scour profile, while the experiment was running, was devised. The experiments were conducted using four different offset ratios and several flow-rates. Results showed dependency of the scour characteristics on Froude number, time and especially the offset ratio. The findings of each experiment were combined dimensionlessly to produce relationships which describe the development of scour characteristics for the tested range of parameters. Scour profiles were found to be similar for a given offset ratio, but differed from one offset ratio to another. The second part of the work was concerned with developing a general integral method capable of the prediction of velocity fields of different flow situations, including those of offset jet impinging on rigidand eroded beds. The combination of strip integral method in a curvilinear system with the k-E and algebraic stress turbulence models provided such a method. Application of this method to a variety of selected test cases revealed the ability of the model to capture the main features of the flow within the considered range of interest. The algebraic stress model was found to give better results in curved and wall effected flows.

No description available.

Thesis (M.S.)--Rochester Institute of Technology, 1992. / Typescript. Includes bibliographical references (leaves 89-90).

Submitted by Reginaldo Soares de Freitas (reginaldo.freitas@ufv.br) on 2017-02-10T18:08:50Z No. of bitstreams: 1 texto completo.pdf: 2640569 bytes, checksum: 5ae7717367c69b7f6342d9e5daf37934 (MD5) / Made available in DSpace on 2017-02-10T18:08:50Z (GMT). No. of bitstreams: 1 texto completo.pdf: 2640569 bytes, checksum: 5ae7717367c69b7f6342d9e5daf37934 (MD5) Previous issue date: 2005-12-20 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / O objetivo deste trabalho foi estudar, por meio de análises térmicas e espectroscópica, o tipo de interação dos componentes anatômicos da polpa branqueada Kraft de eucalipto com tintas de impressão offset. Foi utilizado um classificador de fibras Bauer-McNett, contendo um sistema de peneiras de 20, 48, 100 e 200 mesh, afim de classificar a polpa por conteúdo de elementos anatômicos utilizando a análise de relação fibra/vaso. Após a classificação, as polpas foram nomeadas em baixa, média e alta relação fibra/vaso. Foram utilizadas três tintas de impressão offset de cor azul europa, com composição química similar e três níveis de tack: baixo, médio e alto. As análises térmicas das amostras de tintas, de polpa e da interação destas foram obtidas por Calorimetria Diferencial de Varredura no equipamento DSC-50 e pela técnica de Termogravimetria. Nas análises, observou-se que a evaporação do solvente das tintas offset ocorre com absorção de até 89 cal/g, na faixa de temperatura ambiente a 200 oC. Desta forma, o assentamento da tinta offset no processo de impressão é facilitado com o fornecimento de energia térmica ao sistema. No entanto, a degradação dos outros componentes da tinta acontece, exotermicamente, na faixa de 300 a 500 °C, o que pode causar danos no impresso, justificando, assim, a não utilização deste intervalo de temperatura durante o processo de impressão. A evaporação de água das polpas ocorre, absorvendo até 122 cal/g, na faixa de temperatura ambiente a 200 oC. No entanto, em temperaturas elevadas de 300 a 500 oC, ocorre um fenômeno exotérmico, causando danos irreparáveis à estrutura do papel devido, possivelmente, à despolimerização da cadeia de celulose com formação de levoglucosanas. A temperatura usada, para ocorrência do assentamento da tinta durante a impressão, não afetará a qualidade do papel impresso, desde de que não ultrapasse 200 oC. No entanto, a energia consumida no processo de evaporação de água da polpa será afetada pela porosidade do papel formado, sendo que os papéis mais porosos consumirão menos energia do que os papéis menos porosos. Na interação entre polpa e tinta, o assentamento do pigmento das tintas na polpa ocorre por meio de um processo espontâneo de liberação de energia (processo exotérmico), não havendo necessidade de fornecer energia na forma de calor ao papel impresso para ocorrência deste assentamento. Além disso, de acordo com os baixos valores de entalpia obtidos, este assentamento não ocorre por meio de ligações covalentes, e sim por meio de adsorções físicas (ligações de hidrogênio, forças de van der Waals, atração eletrostática) e por penetração das moléculas do pigmento das tintas nos capilares dos elementos anatômicos da polpa. Maior liberação de energia ocorrerá, durante o assentamento do pigmento das tintas na fração de polpa mais enriquecida por elementos de vasos, devido a uma maior adesão entre as tintas offset e esses elementos anatômicos. Para todas as polpas estudadas, a tinta de tack alto interage mais intensamente durante o assentamento do pigmento da tinta, causando, assim, uma maior adesão entre este tipo de tinta offset e as polpas. / Thermal and spectroscopic analyses were used to analyzing the interaction between the anatomical components of the bleached eucalyptus Kraft pulp and offset printing inks. A Bauer-McNett fiber classifier containing a sieve system with 20, 48, 100 and 200 mesh was used to classifying the pulp based on its anatomical element contents, by the fiber/vessel relationship analysis. The pulps were classified as low, medium, and high fiber/vessel relationship. Three europa blue-colored inks for offset printing with similar chemical composition and three tack levels (low, medium and high) were used. The thermal analyses of the ink and pulp samples as well as their interaction were obtained by Scanning Differential Calorimetry in the equipment DSC- 50 and by the Thermogravimetry technique. According to the analyses, the evaporation of the offset ink solvent occurs with an absorption up to 89 cal/g at the room temperature range of 200 oC. So, the settling of the offset ink over the printing process will be easier if the system is supplied with thermal energy. The degradation of the other ink components happens exothermically at a temperature range from 300 to 500 °C, which may cause damages to the printed paper, therefore justifying the nonuse of this temperature range during the printing process. The evaporation of the water pulps occurs at the room temperature range of 200 oC, by absorbing up to 122 cal/g. At high temperatures between 300 to 500 oC, however, an exothermal phenomenon occurs, so causing irreparable damages to the structure of the paper probably due to depolymerization of the cellulose chain producing levoglucosans. To assure the quality of the printing paper, the temperature used for the settling of the ink during impression should not exceed 200oC. However, the energy consumed over the water evaporation process in the pulps will be affected by the porosity of the produced paper, as the most porous papers will consume less energy than the less porous papers. In the interaction between pulp and ink, the settling of the ink pigment in the pulp occurs by a spontaneous energy liberation process (exothermal process); so, there is no need for supplying energy under heat form to the printing paper for this occurrence. In addition, the low values for enthalpy showed this settling not occurring through covalent connections, but through physical adsorption (hydrogen linkages, van der Walls’ forces, electrostatic attraction), as well as by penetration of the ink pigment molecules into capillaries of the anatomical pulp elements. Higher energy liberation will occur during the settling of the ink pigments in the pulp fraction more enriched by vessel elements, due to higher adhesion between the offset inks and these anatomical elements. For all pulps under study, the high-tack ink interacts more intensely during the settling of the ink pigment, so causing a higher adhesion between this offset ink type and the pulps.

The ink transfer mechanisms in the offset lithographic printing process is consisted by a complex inking roller train which a series of alternately rigid and deformable rollers, are used to precondition and deliver the printing fluid from the ink and fount reservoirs to the image carrier. The lithographic printing inks are complex formulated non-Newtonian fluids with high viscoelastic rheological profile and thixotropic behaviour. A set of ink dilutions was produced based on coldset lithographic printing ink diluted in concentration with Butyl-Diglycol. The rheological profile of the produced inks was examined by detailed rheological characterisation with particular interest on viscosity on tack, thixotropy, viscoelasticity, surface tension, extension and shear viscosity. Further examination established the relationships between shear viscosity and tack focusing on a printing nip between a rigid and elastic roller. A decrease in tack was found to be associated with a decrease in shear and the apparent extension viscosity. Developed imprinting and photographic techniques used to capture and characterise the fundamental phenomena of ribbing and misting associated with ink film splitting at the rollers nip in offset printing. Such techniques used to capture the dynamic profile of those mechanisms on a closed loop distribution system by using a tack meter. The detailed profile of those phenomena was characterised with particular interest on the relationship with the fluids rheological profile and the Capillary number. Extension rheometer was also used to analyse the mechanisms of ribbing and misting phenomena by experimental simulation of a printing nip. A factorial experiment was undertaken based on LI8 Orthogonal Array techniques. The parameters of rollers ratio, ink film thickness, temperature, distribution speed, distribution time and inks viscosity were found to have an influence on misting and ribbing phenomena. Results and analysis established responses and interactions between the process parameters but also between ribbing and misting as essential phenomena with the ink transfer mechanisms in lithographic printing process.

Em resposta à crescente perda de biodiversidade, diversos países adotam políticas de compensação que buscam equilibrar a destruição do habitat local restaurando, aprimorando e / ou protegendo áreas. Tais mecanismos são cada vez mais importantes no setor de mineração, onde a perda de habitat pode ser inevitável devido à rigidez locacional dos recursos minerais e com a coincidência com as áreas de importância da biodiversidade. Buscando contribuir para o avanço da compreensão da prática atual de compensação por perda de biodiversidade, investigamos as práticas adotadas em três minerações de calcário, em conformidade com a Lei da Mata Atlântica, lei federal que visa proteger este hotspot. Foram adotados os mecanismos de proteção e restauração em razões de área de 1: 1 a 1: 5. As principais dificuldades relatadas pelos atores chave foi encontrar áreas adequadas, métodos para calcular perdas residuais e incertezas sobre o sucesso da restauração. As melhores práticas recomendadas internacionalmente são parcialmente seguidas, com maior aderência observada para o caso cuja avaliação de impacto ambiental foi mais detalhada e forneceu uma base mais forte para planejar a compensação. Os resultados sugerem que a qualidade do planejamento e implementação de compensações está diretamente relacionada à qualidade da avaliação de impacto ambiental e, portanto, do licenciamento ambiental. / In response to the increasing loss of biodiversity, several countries have adopted offsetting policies that seek to balance local habitat destruction by restoring, enhancing and/or protecting equivalent values offsite. Such mechanisms are increasingly important in quarrying, where habitat loss may be unavoidable due to colocation of mineral resources and areas of biodiversity importance. Seeking to contribute to advance understanding of the current practice of biodiversity offsetting, we investigated actions required for environmental approval of three limestone quarries in compliance with Brazil\'s Atlantic Forest Act, a federal law that aims at protecting this biodiversity hotspot. Both protection and restoration offsets were applied at area ratios from 1:1.1 to 1:5. The main difficulties reported by practitioners are to find suitable areas, methods to calculate residual losses and uncertainties about the success of restoration. Internationally recommended best practices are partially followed with the highest adherence observed for the case whose environmental impact statement was more detailed and provided a stronger basis for designing the offset. Results suggest that the quality of offset planning and implementation is directly related to the quality of the environmental impact assessment.

Surface offsetting is a valuable tool used in Computer Aided Design (CAD). An offset surface is a collection of points that are at a constant distance from another surface. An offset surface is created in CAD by selecting a surface and then specifying the distance that the surface is to be offset. If a surface is selected and a distance of D is specified, then the resulting offset surface should always be distance D from the original surface. The surface offset tool can be used for many applications. Modeling of composites or other layered manufacturing processes rely heavily on offset surfaces. Thin walled parts such as injection molded components are often modeled using the offset tool. Coating processes can also be modeled using the offset tool. Modern CAD systems have surface offsetting tools and are widely used throughout industry. However, CAD systems often fail to produce valid results. The process of surface offsetting can often result in surface self-intersections as well as surface degeneracies. Self-intersections and degeneracies make the surfaces invalid because they are physically impossible to create and CAD systems cannot use these invalid surfaces to represent solid bodies. The surface offset tool is therefore, one of the most challenging CAD tools to implement. The process of avoiding, detecting and removing surface self-intersections is extremely challenging. Much research in the field of CAD is dedicated to the detection and removal of surface self-intersections. However, the methods proposed in the literature all suffer from robustness problems. The purpose of this research is to introduce a method that creates valid offset surfaces and does not suffer from the problem of creating surface self-intersections. This method uses a numerical approach that approximates the offset surface and avoids all self-intersections. Because no self-intersections are created, the method does not require intersection tests of any kind. The value of this method is demonstrated by comparing its results with results from leading CAD systems.