Simulation of Methanol and Urea Production from Catalytic Conversion of Steel Mill Gases

The time-dependent operation of methanol, ammonia, and urea production units embedded in a steel mill environment is analyzed with dynamic simulation models. From different process concepts and gas availability scenarios, a set of simulation cases is defined with blast furnace gas as carbon and coke oven gas as hydrogen source. Dynamic simulations indicate that significant CO₂ reductions require large amounts of additional H₂ from sustainable sources. From the results, global data such as carbon footprint or energy demands and details about process unit operation are obtained and processed.     

The effect of web of science subject categories on clustering: the case of data-driven methods in business and economic sciences

Scientometrics - The primary goal of this article is to identify the research fronts on the application of data-driven methods in business and economics. For this purpose, the research literature...     

Adherence of staphylococci of different hydrophobicity. Study of various intraocular lenses

BACKGROUND: A major goal in research on intraocular lenses (IOL) is the development of new polymers and modifications to reduce foreign-body reactions after implantation. This effect may be achieved by a reduction in the surface hydrophobicity of the polymers. To illustrate the influence of surface modifications on bacterial adhesiveness, the most often isolated organism in "low-grade" postoperative endophthalmitis, Staphylococcus epidermidis, was used. MATERIALS AND METHODS: For this reason three strains of this species, the type strain ATCC 14990 and two clinical isolates (8687, 6579 I) with different hydrophobic surface properties were studied. IOL, used in the experiments were either made of PMMA or silicone with modified surfaces (unpolished, polished, heparinized). The adhesiveness of H3-thymidin-labeled bacteria was calculated/mm2 of lens surface. Each experiment was performed in triplicate and repeated three times. RESULTS: The hydrophobic-type strain showed stronger adherence to unpolished PMMA surface (8000 bacteria per mm2) compared to the polished (5200 bacteria/mm2). In contrast, the hydrophilic strain adhered with 2000 bacteria/mm2 to the unpolished and with 4200 bacteria/mm2 to the polished surface. Polishing PMMA lenses diminished the differences between the three strains. However, surface passivation of silicone lenses increased the adhesion rate of the hydrophilic strain up to 9600 bacteria/mm2. Treatment of PMMA lenses with heparin increased the adhesiveness of the hydrophilic strain and reduced the adhesion rate of the hydrophobic type strain to 250 bacteria/mm2. CONCLUSIONS: It was demonstrated that bacterial adherence to IOL also involves hydrophobic interactions. Obviously, however, that adherence reflects a complex of interactions between the two surfaces.     

Investigation of an FFT-based solver applied to dynamic flowsheet simulation of agglomeration processes

The growth of particles due to agglomeration is often mathematically described by population balance equations. The numerical evaluation of these equations and applying new methods to their solution is an area of increasing interest. In this contribution, a new approach for solving the agglomeration population balance model based on a separable approximation of the agglomeration kernel and a fast Fourier transformation is investigated. Its applicability within a dynamic flowsheet simulation of continuous agglomeration processes with complex structures is analysed. A simulation framework Dyssol is used to study the new method and compare it to the well-known fixed pivot technique. Studies have shown that the new approach can provide a more efficient solution if certain constraints on the number of classes and on the separation rank of the agglomeration kernel are met.     

Vacuum contact drying of free flowing mechanically agitated particulate materialVakuum-kontakttrocknung von rieselfähigem,mechanisch durchmischtem Granulat

The drying rate of packed and mechanically agitated beds heated by immersed surfaces is controlled by the contact heat transfer resistance at the surface followed by the heat penetration resistance of the wet bulk. Both resistances can be predicted from model equations with sufficient accuracy. The contact resistance and the bulk penetration resistance for packed beds follow from physical properties, while the prediction of the bulk penetration resistance for mechanically agitated beds requires the introduction of an empirical parameter, the so-called mixing number, in order to describe the random particle motion. The mixing number was found to lie between 2 and 25, depending on the dryer type as well as on the Froude number. It is identical for dry and for wet beds.     

Study of on-line adaptive discriminant analysis for EEG-based brain computer interfaces

A study of different on-line adaptive classifiers, using various feature types is presented. Motor imagery brain computer interface (BCI) experiments were carried out with 18 naive able-bodied subjects. Experiments were done with three two-class, cue-based, electroencephalogram (EEG)-based systems. Two continuously adaptive classifiers were tested: adaptive quadratic and linear discriminant analysis. Three feature types were analyzed, adaptive autoregressive parameters, logarithmic band power estimates and the concatenation of both. Results show that all systems are stable and that the concatenation of features with continuously adaptive linear discriminant analysis classifier is the best choice of all. Also, a comparison of the latter with a discontinuously updated linear discriminant analysis, carried out in on-line experiments with six subjects, showed that on-line adaptation performed significantly better than a discontinuous update. Finally a static subject-specific baseline was also provided and used to compare performance measurements of both types of adaptation.     

Scene-based method for spatial misregistration detection in hyperspectral imagery

Hyperspectral imaging (HSI) sensors suffer from spatial misregistration, an artifact that prevents the accurate acquisition of the spectra. Physical considerations let us assume that the influence of the spatial misregistration on the acquired data depends both on the wavelength and on the across-track position. A scene-based method, based on edge detection, is therefore proposed. Such a procedure measures the variation on the spatial location of an edge between its various monochromatic projections, giving an estimation for spatial misregistration, and also allowing identification of misalignments. The method has been applied to several hyperspectral sensors, either prism, or grating-based designs. The results confirm the dependence assumptions on lambda and theta, spectral wavelength and across-track pixel, respectively. Suggestions are also given to correct for spatial misregistration.     

Studies on the current 137Cs body burden of children in Belarus--can the dose be further reduced?

After the Chernobyl reactor accident wide areas of Belarus were contaminated with radioactive fallout. The verification and documentation of the long-term development of radiation doses is still going on. A population group of special concern are the children living in contaminated regions. The annual dose limit of 1 mSv is still exceeded in some cases, essentially due to high body burdens of (137)Cs as indicated by screening measurements with portable incorporation monitors. In this situation the evaluation of possible dose reduction measures in addition to the control of food contamination is being investigated. Special attention is given to the therapeutic application of a pectin preparation (Vitapect), for which a dose-lowering effect is presumed by Belarusian scientists. In a placebo-controlled double-blind study, several groups of contaminated children received a pectin compound named Vitapect for a two-week period during their stay in a sanatorium. For comparison the same number of control groups were given a placebo preparation. The (137)Cs body burden of the children was measured at the beginning and the end. The mean relative reduction of the specific activity within the Vitapect groups was found to be approximately 33%, whereas the specific activity of the children who received a placebo decreased only by approximately 14%, due to clean food supply. It is known that pectins chemically bind cations like caesium in the gastrointestinal tract and thereby increase faecal excretion. Theoretical calculations based on this assumption and considering metabolism processes are qualitatively consistent with the experimentally found retention of radiocaesium in the human body after pectin treatment.