| 1. |
- Bergman, Lars
(author)
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Using Multicoloured Halftone Screens for Offset Print Quality Monitoring
- 2005
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Licentiate thesis (other academic/artistic)abstract
- In the newspaper printing industry, offset is the dominating printing method and the use of multicolour printing has increased rapidly in newspapers during the last decade. The offset printing process relies on the assumption that an uniform film of ink of right thickness is transferred onto the printing areas. The quality of reproduction of colour images in offset printing is dependent on a number of parameters in a chain of steps and in the end it is the amount and the distribution of ink deposited on the substrate that create the sensation and thus the perceived colours. We identify three control points in the offset printing process and present methods for assessing the printing process quality in two of these points:• Methods for determining if the printing plates carry the correct image• Methods for determining the amount of ink deposited onto the newsprintA new concept of colour impression is introduced as a measure of the amount of ink deposited on the newsprint. Two factors contribute to values of the colour impression, the halftone dot-size and ink density. Colour impression values are determined on gray-bars using a CCD-camera based system. Colour impression values can also be determined in an area containing an arbitrary combination of cyan magenta and yellow inks. The correct amount of ink is known either from a reference print or from prepress information. Thus, the deviation of the amount of ink can be determined that can be used as control value by a press operator or as input to a control system.How a closed loop controller can be designed based on the colour impression values is also shown.It is demonstrated that the methods developed can be used for off-line print quality monitoring and ink feed control, or preferably in an online system in a newspaper printing press.
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| 2. |
- Johannesson, Karin, 1982-
(author)
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Analysis of phosphorus retention variations in constructed wetlands receiving variable loads from arable land
- 2011
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Licentiate thesis (other academic/artistic)abstract
- Seven wetlands, constructed on agricultural land in the south of Sweden, were investigated with respect to phosphorus (P) retention. The overall aim was to increase the understanding of P retention and find possible explanations for the variations in retention that have been observed in previous studies. This was done by i) investigating P retention in wetlands receiving various water and P loads, ii) investigating the effect of variations in water flow on P transport, iii) comparing how well retention estimates based on water quality data agreed with measurements of the amount of P accumulated in the sediment.Results showed that P retention was positive in all wetlands, but it was variable (1–58 kg ha-1 yr-1) and months with negative retention were observed in nearly all wetlands. Such monthly negative retention coincided with i) high flow periods, when particulate P was either flushed straight through the wetlands or resuspended from the bottoms, and ii) warm low flow periods, in which case dissolved P was probably released from wetland sediments due to anoxic conditions.The results from the two methods for estimating P retention differed. Based on water quality data, the total P load during four years was 65 kg ha-1 and the mean P retention 2.8 kg ha-1 yr-1, or 17% of the total P load. In contrast, the amount of P accumulated in the inlet zone alone amounted to 78% of the P load, and the P content in the upper sediment of the whole wetland area exceeded the P load with a factor four. This discrepancy showed the need to add studies of sediment accumulation to inflow-outflow estimates for an improved understanding of wetland P retention.
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| 3. |
- Johansson, Pontus, 1975-
(author)
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Design and Development of Recommender Dialogue Systems
- 2004
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Licentiate thesis (other academic/artistic)abstract
- The work in this thesis addresses design and development of multimodal dialogue recommender systems for the home context-of-use. In the design part, two investigations on multimodal recommendation dialogue interaction in the home context are reported on. The first study gives implications for the design of dialogue system interaction including personalization and a three-entity multimodal interaction model accommodating dialogue feedback in order to make the interaction more efficient and successful. In the second study a dialogue corpus of movie recommendation dialogues is collected and analyzed, providing a characterization of such dialogues. We identify three initiative types that need to be addressed in a recommender dialogue system implementation: system-driven preference requests, userdriven information requests, and preference volunteering. Through the process of dialogue distilling, a dialogue control strategy covering system-driven preference requests from the corpus is arrived at.In the development part, an application-driven development process is adopted where reusable generic components evolve through the iterative and incremental refinement of dialogue systems. The Phase Graph Processor (PGP) design pattern is one such evolved component suggesting a phase-based control of dialogue systems. PGP is a generic and flexible micro architecture accommodating frequent change of requirements inherent of agile, evolutionary system development. As PGP has been used in a series of previous information-providing dialogue system projects, a standard phase graph has been established that covers the second initiative type; user-driven information requests. The phase graph is incrementally refined in order to provide user preference modeling, thus addressing the third initiative type, and multimodality as indicated by the user studies. In the iterative development of the multimodal recommender dialogue system MADFILM the phase graph is coupled with the dialogue control strategy in order to cater for the seamless integration of the three initiative types.
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| 4. |
- Chalangar, Ebrahim, PhD student, 1984-
(author)
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Graphene-based nanocomposites for electronics and photocatalysis
- 2019
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Licentiate thesis (other academic/artistic)abstract
- The development of future electronics depends on the availability of suitable functional materials. Printed electronics, for example, relies on access to highly conductive, inexpensive and printable materials, while strong light absorption and low carrier recombination rates are demanded in photocatalysis industry. Despite all efforts to develop new materials, it still remains a challenge to have all the desirable aspects in a single material. One possible route towards novel functional materials, with improved and unprecedented physical properties, is to form composites of different selected materials.In this work, we report on hydrothermal growth and characterization of graphene/zinc oxide (GR/ZnO) nanocomposites, suited for electronics and photocatalysis application. For conductive purposes, highly Al-doped ZnO nanorods grown on graphene nanoplates (GNPs) prevent the GNPs from agglomerating and promote conductive paths between the GNPs. The effect of the ZnO nanorod morphology and GR dispersity on the nanocomposite conductivity and GR/ZnO nanorod bonding strength were investigated by conductivity measurements and optical spectroscopy. The inspected samples show that growth in high pH solutions promotes a better graphene dispersity, higher doping and enhanced bonding between the GNPs and the ZnO nanorods. Growth in low pH solutions yield samples characterized by a higher conductivity and a reduced number of surface defects.In addition, different GR/ZnO nanocomposites, decorated with plasmonic silver iodide (AgI) nanoparticles, were synthesized and analyzed for solar-driven photocatalysis. The addition of Ag/AgI generates a strong surface plasmon resonance effect involving metallic Ag0, which redshifts the optical absorption maximum into the visible light region enhancing the photocatalytic performance under solar irradiation. A wide range of characterization techniques including, electron microscopy, photoelectron spectroscopy and x-ray diffraction confirm a successful formation of photocatalysts.Our findings show that the novel proposed GR-based nanocomposites can lead to further development of efficient photocatalyst materials with applications in removal of organic pollutants, or for fabrication of large volumes of inexpensive porous conjugated GR-semiconductor composites.
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