Global ETD Search

1	Modelling Paper Microstructure and its Role in Toner Transfer in Xerographic Printing Wu, Tao 10 1900 (has links) <p>This thesis investigates paper structure and how its spatial heterogeneity affects the electrostatic and contact forces responsible for the toner transfer in Xerographic printing. Modeling predictions and experiments are reported which link length scales of variation in toner density distribution in Xerographic printing with certain structural length scales in paper.</p> <p>A modified 3D fibre network model is introduced, which is used to simulate handsheet paper microstructure. Specific measures addressed by the model include formation, surface roughness and porosity. Simulated (i.e. virtual) handsheet paper structure is compared with that from specially prepared laboratory handsheet, obtaining a good correspondence between theory and experiments.</p> <p> An efficient Multigrid Poisson solver is used to simulate the electrostatic fields involved in the Xerographic toner transfer process. The distribution of dielectric property is input into the solver either analytically or from simulated 3D paper webs prepared by the fibre network model of paper. A spectral analysis is used to elucidate the relative importance of spatial variations of paper surface, filler and porosity in establishing spatial variations of the electrostatic field. It is found that only long wavelength variations in either surface height, bulk filler or porosity affect variations in electrostatic toner transfer forces to any relevant degree. Furthermore, it is shown that the long wavelength perturbations of the electrostatic field can be modeled using a new 1D effective capacitor model. Direct use of simulated handsheet paper webs - which are described by several heterogeneous measures - shows that to lowest order it is the paper surface structure not formation is responsible in shaping the electrostatic toner field variations.</p> <p> A new platform for modeling toner transfer in Xerographic printing is also introduced. It combines the 3D stochastic fibre network model of paper, the 3D electrostatic field solver, paper compression in the printing nip, and contact adhesion forces acting on toner particles during Xerographic printing. The modeling platform is used to demonstrate that paper-press interactions are critical in shaping the surface of paper, which, in turn, has the greatest influence in controlling both the electrostatic and contact adhesion forces responsible for shaping the distribution of toner transferred to paper during Xerography.</p> / Thesis / Doctor of Philosophy (PhD)
2	Development of a Cost-Effective, Reliable and Versatile Monitoring System for Solar Power Installations in Developing Countries : A Minor Field Study as a Master Thesis of the Master Programme in Engineering Physics, Electrical Engineering Trella, Fredrik, Paakkonen, Nils January 2016 (has links) This report is the result of a conducted Minor Field Study (MFS), to the greatestextent funded by the Swedish International Development Cooperation Agency(SIDA), in an attempt to design a system for evaluating smaller solar power systems indeveloping countries. The study was to the greater part conducted in Nairobi, Kenyain close collaboration with the University of Nairobi. The aim was to develop asystem that would use easily available components and keep the costs to a minimum,yet deliver adequate performance. The system would measure certain parameters of asolar power system and also relevant environmental data in order to evaluate theperformance of the system. Due to the specific competence of the collaboratinggroup at the University of Nairobi, a Kinetis Freescale K64-microcontroller with anARM-Cortex processor was selected as the core of the design. Components wereselected, schematics were drawn, a circuit board was designed and manufactured andsoftware was written. After 12 weeks a somewhat satisfying proof-of-concept wasreached at the end of the field study in Kenya. The project however proved howdifficult it is to go from first idea to a functional proof-of-concept during a limitedtimeframe, and also in an East-African country. The final proof-of-concept was testedat Mpala Research Centre in Kenya and despite containing some flaws proved that itwould indeed be possible to design a working system on the principles discussed inthis report. The system is open-source, so anyone may use and modify it. Solar Power PV Systems Embedded Systems Freescale Freedom Board Freescale Kinetis Kinetis K64 Measurement of Solar Power IV curves Electronics project management Open Source Designspark PCB ECAD CAD EMC PCB manufacturing Prototyping Minor Field Study MFS SIDA SystemC Kenya Nairobi University of Nairobi Justus Simiyu David Karibe Arnold Bett Mjomba Kale Boniface J M Muthoka International Science Programme ISP MIC79110YML LM2576 Island System Hybrid System Solar Charge Controller Solar Power Inverter State Space Model Model Based Development Platform Based Development Makers Just-Us Powers Just-Us ESP8266 Fona mini DHT22 ACS758 Model of Computation MOC Toner-Transfer Toner Transfer 3D-CAD Mpala Research Centre

Search results

Modelling Paper Microstructure and its Role in Toner Transfer in Xerographic Printing

Development of a Cost-Effective, Reliable and Versatile Monitoring System for Solar Power Installations in Developing Countries : A Minor Field Study as a Master Thesis of the Master Programme in Engineering Physics, Electrical Engineering