Ludwig-Bölkow-Systemtechnik

Abstract The conventional method for calculating the bearing capacity is the method derived by Terzaghi, in which the embedment is simulated as a surface surcharge. The total bearing capacity is de...

Abstract The development of large and complex products is currently carried out in small, separate teams of engineers trained in diverse disciplines. Mechanical and electrical engineers are involved in the development of high‐tech and embedded systems as well as software designers. This diversity of disciplines interferes with the efficiency of communication, which is usually carried out in (informal) discussions and by passing documents and models.Within this paper, the passing of documents is explained and enhanced in several levels. Solutions, which are currently available (such as tool chains) are discussed as well as approaches that rest upon a central, document‐ and object‐oriented database. The most elaborate database strategy presented uses similarity relations between documents to infer semantic meaning and facilitate the access to meaningful and relevant development data. This paper concludes with the description of development processes that are introduced with the use of this database solution.

Hydrogen is expected to become an integral part of the Norwegian energy system in the future, primarily as a fuel for transportation. The NorWays project aims at providing decision support for introduction of hydrogen in the Norwegian energy system by modelling the energy system and hydrogen infrastructure build-up at various spatial levels. GIS-based regional hydrogen demand scenarios and hydrogen refuelling station networks have been generated, considering organic growth of regional hydrogen deployment and increasing density of hydrogen users over time. A regional model was used to optimise supply scenarios for these hydrogen refuelling station networks, including choice of production technology (biomass gasification, NG SMR, electrolysis, by-product hydrogen) and delivery (pipeline, truck, and onsite schemes) as well as integrated hydrogen delivery networks by truck and pipeline. The sensitivity to variations in energy price and GHG emission constraint scenarios on hydrogen production and delivery mix and average hydrogen costs was assessed, and conclusions on the effectiveness of policy measures were drawn.

We are currently observing rapid changes in international local energy market structures. The general trend towards competitiveness can be subsummized under terms like liberalization, deregulation and privatization [1]. Starting in the U.S. with the Public Utility Regulatory Policies Act in 1978 various European countries like the UK and Norway followed. Restructuring the energy system will eventually lead to a unification of large electricity and gas suppliers, and to efficient small energy service companies installing decentral, flexible and low cost energy conversion technologies.

HF receiver technology has undergone extremely rapid development over the past ten years, thanks to the technological progress in the semiconductor and line engineering sectors. In the frequency range up to 4 GHz, both the silicon transistor and the GaAs FET are used, while above 4 GHz the GaAs FET provides substantially better noise factors. The HEMT (high electron mobility transistor) is lower in noise in the high GHz range than the GaAs FET.

Exact simulation and optimization of coplanar circuits at microwave and millimeter frequencies is impossible with present commercial circuit analysis programs. The implemented models are generally based on static field-theoretical methods which show large discrepancies at higher frequencies in comparison to exact but time-consuming dynamic field-theoretical methods. Furthermore, the present models cover only few types of symmetrical transmission line structures without any discontinuities. In this paper a new model is presented that can be implemented with general circuit analysis programs or used as a stand-alone tool. It produces proper frequency-dispersive results for a wide range of coplanar structures and a range of discontinuities. The model consists of analytical approximation formulas to describe the results of exact theoretical calculations and/or systematic experimental investigations. Agreement of the new model with results from open literature and in-house field theory as well as from published and in-house measurement is shown to be satisfactory.

Based on the analysis of high efficiency processes and theoretical calculations, a catalogue of requirements was formulated that should be fulfilled by a multicrystalline silicon substrate material to allow cost-effective processing of large-area cells with high efficiency. A simple test process was applied to elucidate if nowadays commercially available silicon materials can at least partially match these requirements. Two different high efficiency cell processes lead to the same results: Two of the five tested materials show negligible degradation of electrical material properties after additional high temperature (1000 °C/1100 °C) treatment and do not need hydrogen passivation. One material needs hydrogen passivation to achieve best results. Two materials show distinct degradation of electrical properties if high temperature treatments are applied.

Silicon solar cells must have an effective surface passivation in order to reach high efficiencies. Silicon dioxide (Si02) provides extremely low interface state densities resulting in record efficiencies for terrestrial silicon solar cells. Unfortunately the refractive index of Si02 is so low that Si02 cannot act as an optimal AR-coating for encapsulated cells. For the use of commercial solar cells one has to look to other alternatives.