Vibration in gear systems

This paper simulates the non-linear vibration of a gear pair including shaft flexibility. Backlash is included because of the clearance between the teeth and the periodic variation in the stiffness of the mesh produces a parametric excitation. This paper shows the different behaviour that may be observed when the additional degree of freedom is added to the single degree of freedom model previously analysed.     

Letter: Note on the Luminosity Distance

We re-derive a formula relating the areal and luminosity distances, entirely in the framework of the classical Maxwell theory, assuming a geometric-optics type condition.     

Nonlinear Analysis of Experimental Time Series of a Straight Turning Process

We investigate vibrations generated in a straight turning process. Applying correlation functions and the Fourier transform to experimental time series, we have analysed their nature. Particularly, we have identified whipping caused by the non-ideal suspension of the cutting workpiece. Our investigation shows also a large stochastic component of vibrations. It can be the effect of random forcing due to the initial roughness of a cutting surface and/or spontaneous chips breaking.     

The application of activated carbon modified by ozone treatment for energy storage

Activated carbon modified by ozone treatment was examined. The process was carried out in a glass reactor under a continuous flow of ozone through a bed of activated carbon for 15, 30, 60, 120, and 240 min. The modified and unmodified carbon materials were characterized by Raman spectroscopy and observed by scanning electron microscopy (SEM). Thermogravimetric analysis was used to estimate the presence of oxygen groups in the carbon structure. The surface area and pore size distribution were examined by nitrogen adsorption method at 77 K. Moreover, Fourier transform infrared (FTIR) spectroscopy was used to estimate the functional groups of modified activated carbon. The carbon content was estimated using the elemental analysis. The process of ozonation increases oxygen functionalities, thus the activated carbon was tested as electrodes for an electrochemical capacitor. The performance of an electrochemical capacitor was estimated by selected alternating (AC) and direct current (DC) methods in 1 M H₂SO₄, 1 M Na₂SO₄, and 6 M KOH electrolytes.

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Influence of the Medium Composition and the Culture Conditions on Surfactin Biosynthesis by a Native Bacillus subtilis natto BS19 Strain

An effective microbial synthesis of surfactin depends on the composition of the culture medium, the culture conditions and the genetic potential of the producer strain. The aim of this study was to evaluate the suitability of various medium components for the surfactin producing strain and to determine the impact of the culture conditions on the biosynthesis of surfactin isoforms by the newly isolated native strain Bacillus subtilis natto BS19. The efficiency of surfactin biosynthesis was determined by measuring the surface tension of the medium before and after submerged culture (SmF) and by qualitative and quantitative analysis of the obtained compound by high performance liquid chromatography. The highest efficiency of surfactin biosynthesis was achieved using starch as the carbon source and yeast extract as the nitrogen source at pH 7.0 and 37 °C. Potato peelings were selected as an effective waste substrate. It was shown that the increase in the percentage of peel extract in the culture medium enhanced the biosynthesis of surfactin (mg/L) (2–30.9%; 4–46.0% and 6–58.2%), while reducing surface tension of the medium by about 50%. The obtained results constitute a promising basis for further research on biosynthesis of surfactin using potato peelings as a cheap alternative to synthetic medium components.     

Synthesis and detailed characterization of cis-dichloridobispicolinatoruthenate(III) as solid and in solution

Three water-soluble ruthenium(III) compounds, Y[cis-RuCl₂(pic)₂]?nH₂O (where pic = picolinate anion, Y = H(Hpic)₂⁺ (1), H₂pic⁺ (2) or K⁺ (3), n = 2, 1.5, and 2.5, respectively), were synthesized and their X-ray structures determined. Compound 1 was fully characterized both as solid and in aqueous solution by elemental analysis, magnetic susceptibility measurements, EPR, IR and UV-visible spectroscopy, cyclic voltammetry, microwave plasma atomic emission, and mass spectrometry, capillary electrophoresis and chromatographic methods. It was shown that the coordination geometry around the low spin (S = ½) Ru^III center is distorted octahedral with the chlorido ligands in a cis configuration. Furthermore, all the measurements showed that the structures in the solid state and solution are absolutely identical with the cis-[RuCl₂(pic)₂]^? anion being inert in aqueous solution. Microbial studies showed that 1 exerts a strong inhibition on the growth and increased mortality level of the bacterial strains – Escherichia coli, Pseudomonas sp., Sarcina sp., Micrococcus sp., Serratia sp., Bacillus cereus, Bacillus subtilis and yeast – Saccharomyces cerevisiae.     

Application of dispersive liquid–liquid microextraction and gas chromatography with mass spectrometry for the determination of oxygenated volatile organic compounds in effluents from the production of petroleum bitumen

We present a new procedure for the determination of oxygenated volatile organic compounds in samples of postoxidative effluents from the production of petroleum bitumens using dispersive liquid–liquid microextraction and gas chromatography with mass spectrometry. The eight extraction parameters were optimized for 43 oxygenated volatile organic compounds. The detection limits obtained ranged from 0.07 to 0.82 μg/mL for most of the analytes, the precision was good (relative standard deviation below 2.91% at the 5 μg/mL level and 4.75% at the limit of quantification), the recoveries for the majority of compounds varied from 70.6 to 118.9%, and the linear range was wide, which demonstrates the usefulness of the procedure. The developed procedure was used for the determination of oxygenated volatile organic compounds in samples of raw postoxidative effluents and in effluents after chemical treatment. In total, 23 compounds at concentration levels from 0.37 to 32.95 μg/mL were identified in real samples. The same samples were also analyzed in the SCAN mode, which resulted in four more phenol derivatives being identified and tentatively determined. The studies demonstrated the need for monitoring volatile organic compounds content in effluents following various treatments due to the formation of secondary oxygenated volatile organic compounds.     

New procedure for the control of the treatment of industrial effluents to remove volatile organosulfur compounds

We present a new procedure for the determination of volatile organosulfur compounds in samples of industrial effluents using dispersive liquid–liquid microextraction and gas chromatography with flame photometric detection. Initially, the extraction parameters were optimized. These included: type and volume of extraction solvent, volume of disperser solvent, salting out effect, pH, time and speed of centrifugation as well as extraction time. The procedure was validated for 30 compounds. The developed procedure has low detection limits of 0.0071–0.49 μg/L and a good precision (relative standard deviation values of 1.2–5.0 and 0.6–4.1% at concentrations of 1 and 10 μg/L, respectively). The procedure was used to determine the content of volatile organosulfur compounds in samples of effluents from the production of bitumens before and after chemical treatment, in which six compounds were identified, including 2‐mercaptoethanol, thiophenol, thioanisole, dipropyl disulfide, 1‐decanethiol, and phenyl isothiocyanate at concentrations ranging from 0.47 to 8.89 μg/L. Problems in the determination of organosulfur compounds related to considerable changes in composition of the effluents, increase in concentration of individual compounds and appearance of secondary pollutants during effluent treatment processes are also discussed.     

On purely non-free finite actions of abelian groups on compact surfaces

A finite group of self-homeomorphisms of a closed orientable surface is said to act on it purely non-freely if each of its elements has a fixed point; we also call it a gpnf-action. In this paper we observe that gpnf-actions exist for an arbitrary finite group and we discuss the minimum genus problem for such actions. We solve it for abelian groups. In the cyclic case we prove that the minimal gpnf-action genus coincides with Harvey’s minimal genus.     

Two‐dimensional fractal Burgers equation with step‐like initial conditions

We consider the two‐dimensional convection–diffusion equation with a fractional Laplacian, supplemented with step‐like initial conditions. We show that the large time behavior of solutions to this IVP is described either by rarefaction waves, or diffusion waves, or suitable self‐similar solutions, depending on the order of the fractional dissipation and on a direction of a convective nonlinearity. Copyright © 2014 John Wiley & Sons, Ltd.