Transforming the energy system - the evolution of the German technological system for solar cells

To improve our understanding of processes involved in the formation and growth of new technological systems in the energy sector and to identify the associated key challenges for policy makers managing the transformation process, we examine the development of the German technological system for solar cells over the past twenty-five years. We use a 'technological system' approach in which we will trace the evolution of actors, networks and institutions that have a bearing on the generation and diffusion of solar cells. An initial preparatory stage lasted until about 1989 and was mainly characterised by knowledge build up induced by a Federal RDD programme. This was followed by a second stage characterised by political struggle over the regulatory framework and subsequently the beginning of a virtuous circle for solar cells. In the concluding discussion, we emphasise four key features of the evolution of the technological system: (1) the role of a coalition of system builders which successfully influenced the regulatory framework so that markets could be formed: (2) the considerable length of the learning period and the large number of actors which need to learn; (3) the importance of policies which form early markets (not only early niche markets, but beyond those) as only markets may induce firms to enter and learn, and (4) the need to run market formation policies simultaneous to policies which maintain technological variety.new technology, growth and formation, solar cells, Germany

History and biology of the reassigned Ruvu Weaver Ploceus holoxanthus

Ploceus holoxanthus was formally described by Karel Johan Gustav Hartlaub in 1891, based on specimens collected by Friedrich  Bohndorff, from Mtoni on the Kingani (now Ruvu) River, Tanzania. Reichenow (1904, p 91) and Zedlitz (1916) synonymized this taxon with African Golden Weaver P. subaureus, although Shelley (1905) and Hartert (1907) had recognized it as a new species. Sclater (1930) and other subsequent authors simply considered P. holoxanthus as a synonym of African Golden Weaver, and eventually it was not even listed as a synonym. In recent years, birds resembling P. holoxanthus have been increasingly photographed. Thus, this taxon was included in a recent phylogeny of the Ploceidae, which recognized P. holoxanthus as a valid species. This paper reviews the history of this taxon, lists all specimens, published references and photographs, and measurements. The nest and eggs are described for the first time. Keywords: Ploceus holoxanthus, Ploceus subaureus, Ruvu River, Mtoni, Bagamoyo, Zedlitz, Tanzani

Preferential centrality as a multi-regional model for spatial interaction and urban agglomeration

Understanding how transportation networks affect regional development has been a long-standing challenge for modellers in several disciplines, both in research and practice. Approaches span between light-weight accessibility and centrality models, to data-heavy land use-transport interaction models. Centrality models have been increasingly employed to support spatial planning on the city-scale, where such techniques are attractive due to their low requirements of socio-economic and demographic data, while they also maintain representations of essential features such as accessibility. However, it has been less clear if such approaches can be successfully extended from the urban to the regional scale. In this paper we demonstrate how a recently introduced centrality measure – preferential centrality – can be used as a modelling framework on the multi-regional scale, while retaining high intra-urban spatial resolution. Centrality is calculated on a zonal level, with local plot characteristics and network travel times as input. Preferential centrality is calculated similarly to Google PageRank and eigenvector centrality, but with preferential growth as an additional component that represents local agglomeration processes. To examine the explanatory power of this approach, we compare computed centrality with empirical land taxation values, using the southern half of Sweden as a case study area. Using a static accessibility model as benchmark, we find that the preferential model has a higher capacity to reproduce empirical patterns, with regard to geographical correlations as well as for probability distributions. Our findings suggest that preferential centrality analysis can have practical value in urban and regional planning contexts, for example when assessing the geographical distribution of impacts from transport infrastructure investments

High sensitivity gas spectroscopy of porous, highly scattering solids

We present minimalistic and cost-efficient instrumentation employing tunable diode laser gas spectroscopy for the characterization of porous and highly scattering solids. The sensitivity reaches 3 x 10(-6) (absorption fraction), and the improvement with respect to previous work in this field is a factor of 10. We also provide the first characterization of the interference phenomenon encountered in high-resolution spectroscopy of turbid samples. Revealing that severe optical interference originates from the samples, we discuss important implications for system design. In addition, we introduce tracking coils and sample rotation as new and efficient tools for interference suppression. The great value of the approach is illustrated in an application addressing structural properties of pharmaceutical materials

Modeling and Optimization of Grade Changes for Multistage Polyethylene Reactors

Grade changes in polyethylene reactors, i.e., changes of operating conditions, are performed on a regular basis to adapt to market demands. In this paper, a dynamic optimization procedure is presented built upon the Modelica language extended with Optimica constructs for formulation of optimization problems. A Modelica library for the Borstar R multistage polyethylene reactors at Borealis AB, consisting of two slurry and one gas phase reactor, has been constructed. Using JModelica.org, a framework to translate dynamic optimization problems to NLP problems, optimal grade transitions between grades currently used at Borealis AB, can be calculated. Optimal inflows and grade key variables are shown

Kombinationsverksamhet - flera verksamheter inom ett lantbruksföretag

In today's Sweden there are approximately 23 000 combination companies, and most of them have a connection with the agricultural sector. The most common type of additional operation is some form of contracting. The aim for this degree project is to answer the following question: which problems and key factors exists within combination operations? The main topic will be within coordination and management questions within agricultural companies with an additional operation. Litterateur written earlier within this subject will be used in this thesis. Mainly litterateur which contains information about combination companies and diversification of some sort. There are also other theories used in this thesis such as; resource based theory and decision making theory in order to understand the problems and key factors within combination companies. In order to investigate the aim of this thesis we have chosen to perform two qualitative interviews with the managers of two different combination companies. These companies are managing traditional farm activities and also contracting operations. The interviews will thereafter be analyzed from the current theories and litterateur. Some of the most important conclusions that has been made from the analyze are that the most limiting resource is time and that the company should adapt its' activities after the available amount of time. Further not being able to work the agricultural operations at an optimal rate because you are busy with the other activities, this may result in high costs. It is also very important be service minded in a combination company