Experimental study of the vortex end in centrifugal separators: The nature of the vortex end

The nature of the vortex end (or the “tail end” or “tip”) in reverse-flow centrifugal gas cleaning equipment, cyclones and swirl tubes, has been studied by visualization using a stroboscope and high-time-resolution pressure measurements. The core of the vortex is shown to bend to the wall of the separator, and rotate around the wall, forming the ring-shaped pattern normally observed at the vortex end. The end of the vortex was found to occur higher in the swirl tube (“less stable vortex”) when the solid loading is increased, and when the volumetric flow rate to the tube is decreased. The frequency with which the vortex core rotates varies with the gas flow rate and was found to be about the same as the frequency with which the gas rotates higher in the separator. The time-averaged wall pressure suddenly decreases in the separator body at the point where the vortex end attaches to the wall.     

3-cis-hexenal,the “Green” reversion flavor of soybean oil

By means of gas-liquid-chromatography the neutral volatile products obtained by stripping oxidized soybean oil were fractionated. The fraction with “green bean” odor (a well-known offflavor of soybean oil) was investigated. By the application of various methods it was possible to isolate the flavor carrier proper and, in spite of its small amount, to complete the analysis to a point at which the structure 3-cis-hexenal seemed highly probable. Synthesis and subsequent comparison with the natural product confirmed the correctness of the assumption. n-Hexanal and 3-trans-hexenal, also found in this fraction, play no significant role in the reversion flavor.     

Modeling carbonation for corrosion risk prediction of concrete structures

Damage of reinforced concrete structures is often caused by corrosion of steel reinforcements due to carbonation. Although literature on carbonation has become vast, a comprehensive numerical model for quantitative prediction of the corrosion risk that allows for environmental influences such as temperature and humidity seems lacking. The aim of the present paper is the development of a theoretical model to predict carbonation of concrete structures. The model describes movement and retention of heat, moisture and carbon dioxide (CO₂) by means of balance equations and diffusion laws. The balance equations are coupled and take into account the interaction between different transport and storing processes. A new mathematical formulation of the function of moisture in balance faithfully represents the moisture-storing properties of a porous media. The evolutionary equation of the reaction of CO₂ is derived from reaction kinetics that are described by the Arrhenius' function. The model is solved by means of an efficient numerical method using a Finite Element concept and numerical time integration techniques. It is verified by using results from experimental tests reported in the literature. Taking into account changing atmospheric conditions, structures are investigated with respect to the corrosion risk of steel reinforcements. Together with threshold values taken from the literature, the numerical results give the corrosion risk of reinforced concrete structures.     

Interactive deformable models with quadratic bases in Bernstein�CB��zier-form

We present a physically based interactive simulation technique for de formable objects. Our method models the geometry as well as the displacements using quadratic basis functions in Bernstein?CBézier form on a tetrahedral finite element mesh. The Bernstein?CBézier formulation yields significant advantages compared to approaches using the monomial form. The implementation is simplified, as spatial derivatives and integrals of the displacement field are obtained analytically avoiding the need for numerical evaluations of the elements?? stiffness matrices. We introduce a novel traversal accounting for adjacency in order to accelerate the reconstruction of the global matrices. We show that our proposed method can compensate the additional effort introduced by the co-rotational formulation to a large extent. We validate our approach on several models and demonstrate new levels of accuracy and performance in comparison to current state-of-the-art.     

Learning GP-BayesFilters via Gaussian process latent variable models

GP-BayesFilters are a general framework for integrating Gaussian process prediction and observation models into Bayesian filtering techniques, including particle filters and extended and unscented Kalman filters. GP-BayesFilters have been shown to be extremely well suited for systems for which accurate parametric models are difficult to obtain. GP-BayesFilters learn non-parametric models from training data containing sequences of control inputs, observations, and ground truth states. The need for ground truth states limits the applicability of GP-BayesFilters to systems for which the ground truth can be estimated without significant overhead. In this paper we introduce GPBF-Learn, a framework for training GP-BayesFilters without ground truth states. Our approach extends Gaussian Process Latent Variable Models to the setting of dynamical robotics systems. We show how weak labels for the ground truth states can be incorporated into the GPBF-Learn framework. The approach is evaluated using a difficult tracking task, namely tracking a slotcar based on inertial measurement unit (IMU) observations only. We also show some special features enabled by this framework, including time alignment, and control replay for both the slotcar, and a robotic arm.     

Curvature continuous offset approximation based on circle approximation using quadratic Bézier biarcs

We present a method for G² end-point interpolation of offset curves using rational Bézier curves. The method is based on a G² end-point interpolation of circular arcs using quadratic Bézier biarcs. We also prove the invariance of the Hausdorff distance between two compatible curves under convolution. Using this result, we obtain the exact Hausdorff distance between an offset curve and its approximation by our method. We present the approximation algorithm and give numerical examples.     

Studies on the removal of phosphorus and sulfur from Fe-C and Fe-C-Mn melts at 1350°C

Laboratory studies have been performed on simultaneous dephosphorization and desulfurization of Si-free Fe-4.5 % C melts with [P]_o = 0.11 wt.% and [S]_o = 0.04 wt.% in MF induction furnaces at 1 350°C. In these investigations, CaO- or Na₂CO₃-based fluxes were used and the techniques of powder injection or single top slag addition were applied. The following results have been obtained:

• – The effectiveness of lime and soda-based fluxes with regard to dephosphorization is practically the same. But a lower sulfur level is attained when Na₂CO₃-based fluxes are used.
• – In the injection experiments, efficiencies of η_P = 80% for dephosphorization and η_s = 90% for desulfurization are easily reached at a powder consumption of 50 to 60 g/kg. But a further increase of the η values requires a remarkable increase in the amount of injected powder. Top slag addition instead of powder injection is less effective, in general.
• – Apparent rate constants k_[P] and k_[S] from 0.05 to 0.3 min^?1 have been determined in the initial stage of injection depending on the relative amount of injected flux. In the top slag experiments, the k_[P] and k_[S] values were practically constant at a level of 0.1 min^?1.

Furthermore, dephosphorization of molten Fe-C-Mn alloys at 1 350°C has been studied at variable Mn content. It is predicted from thermodynamic data and confirmed by experiments that dephosphorization lessens with increasing Mn content in the range from 0 to 15 wt.%.