Until 2020, 49% of Sweden's use of energy must derive from renewable sources. Greenhouse gases must as well decline with 40% compared to 1990 as a part of Sweden's 16 environmental objectives. Biogas is part of the effort to achieve these objectives, but as the demand for biogas increases, more substrates are needed to meet the demand. The purpose is to investigate the conditions for pea residue as substrate by performing lab-scale mesophilic digestion with different fractions and notch lengths and then to summarize pea residue as a substrate for biogas production. During anaerobic digestion, 1000 ml bottles were used as reactors for digestion. Analyses of gas production, gas composition, content of dry matter and organic matter, carbon / nitrogen-ratio and pH have been performed.The results from lab scale digestion show that the pea residue has a methane potential of 300-400 liters of methane per kg VS during 25 days of anaerobic mesophilic digestion. Chopped pea residue had a slightly higher methane production than untreated pea residue.. The substrate was very difficult to mix up in a regular household blender because of long and tough fibers. This suggests that the substrate requires to be chopped in order to avoid difficulties with management in pumps. Profitability may be a problem if you chop pea residue as the machine being used is expensive and the increase in methane yield as a result of chopping is too small for the pretreatment to be worthwhile. The cost for collecting and chopping the pea residue has been estimated to 473 SEK per hectare or 0,1 SEK per kWh.Practical experience of digesting chopped ensiled pea residue in large-scale facility shows that the substrate works well in pumps and does not affect the process negatively in any way, which suggests that chopping and ensiling pea residue is preferable. Theoretically, there is an energy potential of pea residue amounting to 40 GWh in Skåne and Halland, which roughly corresponds to the fuel consumption of 130 biogas buses annually. The biogas needs to be upgraded before this is possible.Environmental benefits of digesting pea residue include reducing nitrous oxide emissions of 500-1200g per hectare. Other environmental benefits include the reduction of ammonia emissions and nitrate leaching. Biogas as a fuel is neutral as regards carbon dioxide emissions and can replace fossil fuels. Crop residues as a substrate for biogas production do not compete with land for food production.

Silk-weaving in Sweden during the 19th century. Textiles and texts - An evaluation of the source material. With the rich material available, 19th century silk-weaving invites to studies on industrialisation processes. The purpose of this licentiate thesis is to present and discuss an empirical material regarding silk production in Sweden in the 19th century, to examine the possibilities and problems of different kinds of materials when used as source materials, and to describe how this material can be systematized and analysed in relation to the perspective of a textile scientific interpretation. The introductory sections of the thesis provide a background to textile research and the subject of textile science. This is followed by an overview of previous research on silk-weaving in Sweden and a historical overview of silk-weaving in Sweden, the Jacquard machine, and the K.A. Almgren Sidenväveri, where large parts of the source material have been preserved. After these overviews, the research material is described and systematized: first the main materials, textiles, machines and other objects, and then the various written sources. By way of conclusion, the empirical material is summarized in a critical discussion where the various groups of materials are evaluated in comparison to one another. A discussion on theory and methodology regarding objects as sources and the use of experience-based knowledge in academic research is developed in connection to the critical discussion. Finally, the potential of the material is demonstrated through a textile example. The presentation is an introduction to the cultural-historical analysis that will follow in the PhD thesis. Here, the empirical material will be analysed through the use of knowledge in handicrafts, which may create new dimensions of silk production in Sweden and the complexity of the industrialisation process.

In this thesis, we study Schrödinger equations with an external magnetic field. In the first part, we are interested in an eigenvalue problem. We work in an open, bounded and simply connected domain in dimension two. We consider a magnetic potential singular at one point in the domain, and related to the magnetic field being a multiple of a Dirac delta. Those two objects are related to the Bohm-Aharonov effect, in which a charged particle is influenced by the presence of the magnetic potential although it remains in a region where the magnetic field is zero. We consider the Schrödinger magnetic operator appearing in the Schrödinger equation in presence of an external magnetic field. We want to study the spectrum of this operator, and more particularly how it varies when the singular point moves in the domain. We prove some results of continuity and differentiability of the eigenvalues when the singular point moves in the domain or approaches its boundary. Finally, in case of half-integer circulation of the magnetic potential, we study some asymptotic behaviour of the eigenvalues close to their critical points. In the second part, we study nonlinear Schrödinger equations in a cylindrically setting. We are interested in the semiclassical limit of the equation. We prove the existence of a semiclassical solution concentrating on a circle. Moreover, the radius of that circle is determined by the electric potential, but also by the magnetic potential. This result is totally new with respect to the ones before, in which the concentration is driven only by the electric potential. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished