FTIR Characterization of Fe3+–OH Groups in Fe–H–BEA Zeolite: Interaction with CO and NO

Fe³⁺–OH groups of a Fe–H–BEA sample prepared by conventional ion-exchange method are characterized by an IR band at 3686–3684 cm^?1. They exhibit a weak acidity: upon low-temperature CO adsorption the O–H stretching modes are blue shifted by 100 cm^?1 and the respective carbonyl adducts are observed at 2158 cm^?1. The Fe³⁺–OH groups are reduced at room temperature by NO to form Fe²⁺–NO species and NO⁺ groups in cationic positions. Desorption of pre-adsorbed NO at temperatures above 373 K regenerates the Fe³⁺–OH groups. The relation of the Fe³⁺–OH species to the so-called α-oxygen is discussed.     

Hypothetical integration of a fast reactor to the fuel cycle in Slovakia

The inspiration for dealing with the topic of fuel cycle back-end was attendance at a European project called RED-IMPACT – Impact of Partitioning Transmutation and Waste Reduction Technologies. This paper includes an image how to re-use energetic potential of stored spent fuel and at the same time how to effectively reduce spent fuel and radioactive waste volumes aimed for deep repositories. The first part is based on the analysis of Pu and minor actinides (MA) content in actual VVER-440 spent fuel stored in Slovakia. The next parts present the hypothetical possibilities of reprocessing and Pu re-use in a fast reactor under Slovak conditions. For the hypothetical transmutation of heavy nuclides (Pu and MA) contained in Slovak spent fuel a SUPERPHENIX (SPX) fast reactor with increased power was chosen because a fast nuclear reactor cooled by sodium belongs to the group of Generation IV reactor systems. This article deals with the analysis of power production and fuel cycle indicators. The indicators of the SPX calculation model were compared with the results of the VVER-440 spent fuel with the initial fuel enrichment of 4.25% U-235 + 3.35% Gd₂O₃. The created SPX model in the spectral computer code HELIOS 1.10 consists of a fissile (fuel) and a fertile part (blanket). All kinds of calculations were performed by the computer code HELIOS 1.10. This study also exposes the HELIOS modelling and simulating borders.     

Idealisation of ships with large hatch openings by a thin-walled rod of open section on many elastic supports

The open part of the ship's hull with large hatch openings is considered as a prismatic thin-walled rod of open section on many elastic supports subjected to torsion. The stiffness of deck strips and the ship's sides in the deck plane is taken into account by elastic supports. Internal forces and displacements of the open part of the hull and deck strips are obtained in an analytical form, using the method of initial parameters. Stresses and displacements can be presented numerically and graphically, in a form suitable for preliminary calculations. A numerical example is given.     

Optimal approximate designs for comparison with control in dose-escalation studies

Consider an experiment, in which a new drug is tested for the first time on human subjects, namely healthy volunteers. Such experiments are often performed as dose-escalation studies: a set of increasing doses is preselected; individuals are grouped into cohorts; and in each cohort, dose number i can be administered only if dose number \(i-1\) has already been tested in the previous cohort. If an adverse effect of a dose is observed, the experiment is stopped, and thus, no subjects are exposed to higher doses. In this paper, we assume that the response is affected both by the dose or placebo effects and by the cohort effects. We provide optimal approximate designs for estimating the effects of the drug doses compared with the placebo with respect to selected optimality criteria (E-, MV- and LV-optimality). In particular, we prove the optimality of the so-called Senn designs with respect to all of the studied optimality criteria, and we provide optimal extensions of these designs for selected criteria.     

The influence of lubricants on cam failure

This paper studies the effects of lubricants on the failure and reliability of cams. Experimental investigations of the influence of lubricants on cam failure have been carried out at a metalworking factory. This paper presents following:

– A classification of industrial oils for cams. To establish this classification, two essentials of parameters have been taken into account: the environment (ambient temperature) and the cam operating conditions (load and sliding velocity).

– A flowchart of lubricating oil selection procedure for cams as a function of all relevant influencing factors.

– An analysis of the symptoms and the causes of failure of machine tool cams.

– An analysis of the average life and curves of cam reliability of machine tools as a function of tribological properties of some industrial oils.

The obtained results have proved that the tribological properties of lubricants has a great influence on:

– reduction of failures,

– extension of the life and

– increase of the reliability of cams.

     

Analysis of the efficiency of electronic reverse auction settings: big data evidence

Electronic Commerce Research - Despite the existence of research in the field of electronic reverse auctions (eRAs), there is still a limited understanding of the determinants of auction savings...     

Iron-Sepiolite High-Performance Magnetorheological Polishing Fluid with Reduced Sedimentation

A sedimentation-stable magnetorheological (MR) polishing slurry on the basis of ferrofluid, iron particles, Al₂O_3, and clay nanofiller in the form of sepiolite intended for MR polishing has been designed, prepared, and its polishing efficiency verified. Added clay substantially improved sedimentation stability of the slurry, decreasing its sedimentation rate to a quarter of its original value (1.8 to 0.45 mg s⁻¹) while otherwise maintaining its good abrasive properties. The magnetisation curve measurement proved that designed slurry is soft magnetic material with no hysteresis, and its further suitability for MR polishing was confirmed by its magnetorheology namely in the quadratically increased yield stress due to the effect of applied magnetic field (0 to 600 kA m⁻¹). The efficiency of the MR polishing process was tested on the flat samples of injection-moulded polyamide and verified by surface roughness/3D texture measurement. The resulting new composition of the MR polishing slurry exhibits a long-term stable system with a wide application window in the MR polishing process.