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Popular Abstract in Swedish Ett ökade förbrukningen av fossila bränslen kommer att accelerera den globala uppvärmningen med oöverskådlig inverkan på oss och vår miljö. Utvecklingen av alternativa, förnybara och miljömässigt rena energiformer är därför helt essentiell. En möjlig lösning är att skapa artificiell fotosyntes, där solenergi omvandlas till bränsle (till exempel vätgas) i en process där A continuing use of fossil fuels will accelerate global warning and result in severe consequences for the environment and thereby also us. Development of alternative, sustainable and environmentally friendly energy sources is therefore crucial. One approach is to create an artificial photosynthetic system that converts sunshine into fuel (e.g. hydrogen gas) by splitting water molecules. However, i

The critical effect of load representation in voltage stability studies is discussed in this paper. Under the same conditions in the system, the load representation will affect the location of the operating point in a P-V curve representation, leading the system closer to or further from the collapse point. The use of dynamic load models in voltage stability studies is motivated, especially in tho

Currently biofuels have strong political support, both in the EU and Sweden. The EU has, for example, set a target for the use of renewable fuels in the transportation sector stating that all EU member states should use 10% renewable fuels for transport by 2020. Fulfilling this ambition will lead to an enormous market for biofuels during the coming decade. To avoid increasing production of biofuel

Initializing a model written in Modelica translates to finding consistent initial values to the underlying DAE. Adding initial equations and conditions creates a system of non-linear equations that can be solved for the initial configuration. This paper reports an implementation of Newton's method to solve the non-linear initialization system. This implementation also uses a regularization method

Downtimes in a manufacturing cell, line or individual machines are characterized by a stochastic behavior that their frequency and their duration display. A method is presented here for analyzing this dynamic behavior from a cost perspective. An important element of the method is statistical analysis of downtimes, including empirical distribution functions pertaining to downtimes of specific types

Due to the deregulation of the electricity market the power producers are forced to continuously investigate various means of maintaining/increasing their profits. Improving the electrical efficiency through hardware upgrades is probably the most commonly employed measure, although the interest for enhancements with regard to plant operation is on the rise. Plant operation improvement is often m

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Abstract Background: Many people with a visual impairment have only peripheral vision. However, there is limited knowledge of the peripheral optics of the eye and only some measurements are available in this field. Methods: We simulated the paths of peripheral rays through the eye by means of raytracing. Five programs were compared. The OSLO raytracing software proved to be not only the best one