Digital Availability of Product Information for Collaborative Engineering of Spacecraft

In this paper, we introduce a system to collect product information from manufacturers and make it available in tools that are used for concurrent design of spacecraft. The planning of a spacecraft needs experts from different disciplines, like propulsion, power, and thermal. Since these different disciplines rely on each other there is a high need for communication between them, which is often realized by a Model-Based Systems Engineering (MBSE) process and corresponding tools. We show by comparison that the product information provided by manufacturers often does not match the information needed by MBSE tools on a syntactic or semantic level. The information from manufacturers is also currently not available in machine-readable formats. Afterwards, we present a prototype of a system that makes product information from manufacturers directly available in MBSE tools, in a machine-readable way.Comment: accepted at CDVE201

Contact angle measurements an empirical diagnostic method for evaluation of thin film solar cell absorbers CuInS2

An empirical diagnostic method for the evaluation of solar cell grade CuInS2 absorbers has been developed. The method involves the measurement of the contact angle between water and the CuInS2 absorber before fabrication of a solar cell. The contact angle is expected to depend upon local inhomogeneity, chemical composition and surface morphology of the CuInS2 absorber. The variation of these factors on the surface is supported with scanning electron micrographs, chemical analyses, laser scanning photocurrent mapping of various CuInS2 absorbers and measurements of the solar cell performance. The contact angle has been found to be different at different places on the CuInS2 surface. Empirically, it was found that for high conversion ef amp; 64257;ciency solar cells gt;8 10.5 , the contact angle on CuInS2 absorbers ranges between 53 and 63 . For low conversion ef amp; 64257;ciency solar cells o6 , it is between 48 and 50 . Therefore, it is seen that contact angle measurements on CuInS2 absorbers can be used to assess the quality of CuInS2 absorbers prior to solar cell fabricatio

Imaging UV photoactivity and photocatalysis of TiO2 films

Differently prepared thin layers of TiO2 were scanned with a UV laser to produce images of photoactivity. Flame oxidized, galvanically oxidized, sputtered and Sol Gel prepared layers were compared by determining images of UV induced photocurrent under otherwise constant conditions. Significant differences were found between the samples, both with respect to distribution and intensity of photoactivity. Also within the same sample, variations in photoactivity of up to one order of magnitude was found, which partially could be traced back to characteristic features of the preparation technique. The UV photoactivity of TiO2 layers was shown to depend on the preparation procedure and the duration of photoelectrochemical activity. The developed technique is discussed as a strategy for optimizing photoactivity of TiO2 layers. By locally immobilizing oxidants e.g. methanol, chlorophenol within a deposited porous sodium silicate layer, enhanced photooxidation activity can be identified in form of patches of increased photocurrent density. In this way the technique will allow minimal approaches to photooxidation and detoxification of chemicals. The described UV imaging techniques can be developed as a useful tool for optimizing photocatalytic layers for solar detoxification and surface cleanin

Photoelectrochemically induced periodical deposition patterns of platinum on p InP. Part 2 kinetic model

A kinetic model is presented which rationalizes the previous observation of spatially periodical platinum deposition induced photocathodically by a moving laser spot on p InP. The model is similar to that of the Liesegang phenomenon. It includes the following processes nucleation of ad atoms, growth of nuclei, formation of a depletion zone, limitation of mass transport by diffusion, shift of the photocathodic reaction zone along with the moving laser spot. Computer simulations of the model equations reproduce the experimentally found periodical platinum deposition and demonstrate the spatiotemporal evolution of the number of nuclei, the deposition peaks and the corresponding hexacloro platinate IV concentration profile. The influence of the model parameters is discusse

The function of TiO2 with respect to sensitizer stability in nano crystalline dye solar cells

Dyes of characteristically different composition have been tested with respect to long term stability in operating standardized dye sensitized cells during a time period of up to 3600 hours. Selective solar illumination, the use of graded filters and imaging of photocurrents revealed that degradation is linked to the density of photocurrent passed. Photoelectrochemical degradation was observed with all sensitizers investigated. Sensitization was less efficient and sensitizers less photostable with nano structured ZnO compared to nano structured TiO2. The best performance was confirmed for cis RuII dcbpyH2 2 NCS 2 on TiO2. However it was 7 10 times less stable under otherwise identical conditions on ZnO. Stability is favoured by carboxylate anchoring and metal centred electron transfer. In presence of TiO2 it is enhanced by formation of a stabilizing charge transfer complex between oxidised Ru dye and back bonding interfacial Ti3 states. This is considered to be the main reason for the ongoing use of expensive Ru complexes in combination with TiO2.The local surface chemistry of the nano crystalline TiO2 turned out to be a crucial factor for sensitizer stability and requires further investigatio

Catalyst Development for CO₂ Hydrogenation to Fuels

New active and selective catalyst compositions for the hydrogenation of CO2 to mainly fuel-type higher hydrocarbons were developed by application of an evolutionary strategy. It was shown that Fe and K supported on TiO2 and modified by Cu plus other modifiers resulted in highest selectivity for C5–C15 hydrocarbons at high degrees of CO2 conversion. Co containing catalysts were less suited since they produced methane and light hydrocarbons with high selectivities. A detailed study of reaction conditions showed that selected catalyst compositions were able to reach high CO2 conversion with still low selectivities to methane at higher reaction temperatures and a higher H2/CO2 ratio. conversion with still low selectivities to methane at higher reaction temperatures and a higher H2/CO2 ratio