Essential Matrix Estimation Using Gauss-Newton Iterations on a Manifold

A novel approach for essential matrix estimation is presented, this being a key task in stereo vision processing. We estimate the essential matrix from point correspondences between a stereo image pair, assuming that the internal camera parameters are known. The set of essential matrices forms a smooth manifold, and a suitable cost function can be defined on this manifold such that its minimum is the desired essential matrix. We seek a computationally efficient optimization scheme towards meeting the demands of on-line processing of video images. Our work extends and improves the earlier research by Ma et al., who proposed an intrinsic Riemannian Newton method for essential matrix computations. In contrast to Ma et al., we propose three Gauss-Newton type algorithms that have improved convergence properties and reduced computational cost. The first one is based on a novel intrinsic Newton method, using the normal Riemannian metric on the manifold consisting of all essential matrices. The other two methods are Newton-like methods, that are more efficient from a numerical point of view. Local quadratic convergence of the algorithms is shown, based on a careful analysis of the underlying geometry of the problem.     

Swing-up of the double pendulum on a cart by feedforward and feedback control with experimental validation

The swing-up maneuver of the double pendulum on a cart serves to demonstrate a new approach of inversion-based feedforward control design introduced recently. The concept treats the transition task as a nonlinear two-point boundary value problem of the internal dynamics by providing free parameters in the desired output trajectory for the cart position. A feedback control is designed with linear methods to stabilize the swing-up maneuver. The emphasis of the paper is on the experimental realization of the double pendulum swing-up, which reveals the accuracy of the feedforward/feedback control scheme.     

Accurate and self-consistent ocean color algorithm: simultaneous retrieval of aerosol optical properties and chlorophyll concentrations

A new algorithm has been developed for simultaneous retrieval of aerosol optical properties and chlorophyll concentrations in case I waters. This algorithm is based on an improved complete model for the inherent optical properties and accurate simulations of the radiative transfer process in the coupled atmosphere-ocean system. It has been tested against synthetic radiances generated for the Sea-Viewing Wide Field-of-View Sensor (SeaWiFS) channels and has been shown to be robust and accurate. A unique feature of this algorithm is that it uses the measured radiances in both near-IR and visible channels to find that combination of chlorophyll concentration and aerosol optical properties that minimizes the error across the spectrum. Thus the error in the retrieved quantities can be quantified.     

Parameterization and analysis of the optical absorption and scattering coefficients in a western Norwegian fjord: a case II water study

Based on statistical analyses of optical properties measured during a whole year of monthly cruises in a Norwegian fjord, we constructed a two-component model for the absorption and scattering coefficients for visible light. The input to the model is the concentrations of yellow substance and chlorophyll a. Because of the presence of a significant amount of nonalgal particles in coastal water, we assume that the absorption and scattering coefficients approach constant background values when the concentration of chlorophyll a approaches zero. The model works reasonably for a variety of optical conditions encountered throughout the year, with a possible exception during a bloom of the Emiliania huxleyi algae in June.     

Die Arbeitslinien von metallischen Drähten und Stäben – Hochfester Stahldraht für Seile und Bündel in der Bautechnik

An metallischen Werkstoffen mit runder Querschnittsform Durchführung von Feindehnungsmessungen bis zu Längsdehnungen von 3% bei einaxialen Zugversuchen mit Hilfe von Dehnungsmeßstreifen. Zusätzliche Kennwerte für das Ende der Gleichmaßdehnung und für die Rißlast. Gegenüberstellung der Meß- und Rechenwerte.     

Die Werkstoffbeanspruchung im quergepreßten Seildraht – Hochfester Stahldraht für Seile und Bündel in der Bautechnik

An einem Runddraht mit 4 mm Dmr. der fünften Lage eines vollverschlossenen Spiralseiles mit 80 mm Dmr. Ermittlung der mechanischen Beanspruchungen, die sich aus ruhenden und wechselnden Lasten auf einen Runddraht im Drahtverband eines Spiralseiles ergeben. Für die zulässige Gebrauchslast quantitative Bestimmung der Größe und des Verlaufs der Spannungen im Draht als Folge der Vorbehandlung, der Verseilung und seiner Lagerungsbedingungen im Seil. Errechnung von Vergleichsspannungen als Maßt ür die Größe der Werkstoffanstrengung im Draht. Die Länge der Reibwege von benachbarten Drähten für den Wechsellastanteil.     

Aromatische Pinakole als Polymerisationsinitiatoren

Aromatic pinacols are capable of starting the free radical polymerization of vinyl compounds. The free radical polymerization is initiated mainly by hydrogen atoms stemming from the diarylhydroxymethyl radicals formed through the thermal decomposition of the initiator.     

Determination of metal inventory and current efficiency in commercial aluminum reduction cells

A method for the determination of the metal inventory in commercial aluminum reduction cells, based on radioisotope dilution, has been developed, employing a¹⁹⁸Au tracer. By taking a large number of samples from the cells, the current efficiency is evaluated from the slope of the cumulative metal inventory vs time data. The method allows a determination of the current efficiency over a period of 2 to 3 days with a relative precision of approximately 1 pct. The paper gives a thorough discussion of the sources of error inherent in the procedure suggested. Formerly Research Associate at the same University.