Canonical form observer design for non-linear time-variable systems

An observer of canonical (phase-variable) form for non-linear time-variable systems is introduced. The development of this non-linear time-variable form requires regularity of the non-linear time-variable- observability matrix of the system. From the relationships derived during the development, it follows that a non-linear time-variable observer can be dimensioned by an eigenvalue assignment with respect to the canonical state coordinates if a linearization of system non-linearities about the reconstructed state trajectories is permissible. This is an assumption similar to that of the extended Kalman filter based on a linearization about the current estimate.     

On the feasibility of cloud stereoscopy and wind determination with the Along-Track Scanning Radiometer

The Along-Track Scanning Radiometer (ATSR) is a planned ERS-1 payload for accurate sea-surface temperature measurements under two different incidence angles from a conical scan. It is investigated whether it can additionally be used for cloud stereoscopy and wind determinations as proposed by DFVLR for the Stereo Line Scanner (SLS). Although not designed for these types of measurements the ATSR seems very useful for a pilot experiment with only a lower resolution than proposed for the SLS.

Because of distortions that occur with the conical scan of the ATSR, synthetic stereo imaging with additional height corrections is recommended instead of direct stereoscopy. Quantitative cloud heights can be derived from parallax measurements. Estimations of the influence of the pixel size and the alignment changes lead to cloud-height accuracies of up to ±750m. The influence of cloud motion on the parallax may be corrected with cloud-motion vectors derived from geosynchronous satellite data.

An experiment for wind determinations from ATSR data is proposed in the vicinity of radiosonde stations which would lead to a resolution of up to about ± 8m/s. The necessary independent height informations for that are derived from ATSR infrared (IR) cloud temperatures and radiosonde temperature profiles (accuracy ±400m). Since all uncertainties were estimated rather too high than too low an increase in the accuracy may be expected for all results.     

IMPLEMENTING GIBSONIAN VIRTUAL ENVIRONMENTS

We speculate on the possibilities for a realization of the idea of a three di mensional cyberspace as sketched in the novels of William Gibson using todays technology Virtual reality and global networks such as the Internet together can provide the fundamentals for such an effort From an examina tion of the technological principles of a Gibsonian virtual environment we conclude what properties such an implementation must have An implemen tation of a system with these properties faces a number of problems in the large and in the small in particular the semantics of the virtual environ ment and its inhabitants must be defined We also report on our ongoing implementation of a prototype software system that was designed to evalu ate the feasibility of these ideas     

Secondary zoospores in the algal endoparasite <i>Maullinia ectocarpii</i> (Plasmodiophoromycota)

The present paper deals with the ultrastructure of zoospores produced by the plasmodiophorid Maullinia ectocarpii, living in the marine algal host Ectocarpus siliculosus. The zoospores described here are very similar to secondary zoospores of Polymyxa graminis and Phagomyxa sp. (the latter an algal endoparasite, also). Our results indicate that M. ectocarpii produces two types of plasmodia, and suggest that is a species with a complete life cycle, as it is known for all the Plasmodiophormycota that have been studied. Sporogenic and sporangial plasmodia produce, respectively, primary zoospores with parallel flagella within thick walled resting sporangia, and secondary zoospores with opposite flagella within thin walled sporangia.     

MODIFICATION OF THE LOW-MOLECULAR WEIGHT BASIC ALBUMIN FRACTION FROM RAPESEED (BRASSICA NAPUS L.) BY ACETYLATION PART 1. CHEMICAL AND PHYSICOCHEMICAL ASPECTS1

The chemical and physicochemical changes of the low-molecular weight basic albumin fraction from rapeseed, as a function of degree of acetylation, were studied using amino and ester groups analyses, PAGE electrophoresis, isoelectric focusing, viscometry, circular dichroism and fluorescence spectroscopy. The surface hydrophobicity was evaluated by means of the ANS fluorescence probe technique. The protein was readily acetylated at the amino groups by addition of acetic anhydride. Acetylation of amino acid hydroxyl groups was significantly slower and proceeded in the presence of an excess of the reagent after the amino groups had already been blocked. Acetylation resulted in protein species with isoelectric points at pH 7.6, 6.6, 5.95 and 5.4. The intrinsic viscosity of the native protein fraction dropped from 0.159 dlg^?1 to 0.038 dlg^?1 at a moderate degree of modification. The secondary structure of the protein, characterized by a content of 40–45% helix conformation, was not significantly influenced by acetylation. Modification did not result in wavelength shifts of the peaks in the near ultraviolet CD and fluorescence spectra. However, the negative ellipticities in the 250–270 nm region of the CD spectrum increased markedly with increasing degree of acetylation. The surface hydrophobicity increased linearly with the amount of acetyl groups introduced into the protein.     

THE CdTe THIN FILM SOLAR CELL - AN OVERVIEW

The basic physical aspects of the CdTe-thin film solar cell in its various embodiments are reviewed. Deposition techniques are briefly described, results of present pilot-line production efforts and the future potential are discussed, which make the CdTe thin film solar cell a promising candidate for low cost and well-above 10% module-efficiency. A detailed costing model for thin film solar cells is presented illustrating that low cost of around 0.9 ECU/W_p will be achievable upon suitable upscaling of production.     

SOME PHENOMENA IN CdTe/CdS THIN FILM SOLAR CELLS MADE BY CLOSE-SPACED SUBLIMATION

CdTe/CdS heterojunction thin film solar cells of 11.7% efficiency have been made by close-spaced sublimation of CdTe. Some results regarding the influence of the CdCI₂ treatment and contacting are given stressing the requirement of more in-depth analysis of the CdTe cells made by different processes in order to understand the common and basic mechanisms better.     

THERMAL CONDUCTIVITY AND DIFFUSIVITY OF SHELLED CORN AND GRAIN

Increasing energy costs have stressed the importance of calculation of heat and mass transfer in a grain bulk in order to be able to optimize drying facilities. Therefore values for the thermal conductivity and diffusivity of grain and especially shelled corn were determined. The investigations were carried out for single kernels as well as for grain and corn in bulk. Thermal conductivity and diffusivity were found to be mainly dependent on moisture content. Regression analyses showed a good correlation between moisture content and thermal conductivity or diffusivity, respectively.