Influence of Activation and the HDS Reaction on the Structure of Magnesium Fluoride-Supported Ru Catalysts Derived from Ruthenium Chloride Hydrate

The effect of water and reductants (CO and H₂) on the decomposition of NO _x stored on BaO/Al₂O₃ at 300 °C has been investigated. Water eliminates the initial rapid total uptake of NO₂ but has little effect on the subsequent formation of nitrates that is accompanied by evolution of NO. Water hinders liberation of NO₂ and NO during temperature-programmed decomposition of stored NO _x . Both CO and H₂ lower the temperatures required for decomposition through reduction of NO₂ to NO and N₂ thus restricting NO₂ readsorption. The rate of reduction is lower with H₂ than with CO.     

Structure and properties of polypropylene/low‐density polyethylene blends grafted with itaconic acid in the course of reactive extrusion

This study was concerned with the structural features and mechanical properties of polypropylene (PP)/low‐density polyethylene (LDPE) blends, which after compounding were modified by the free‐radical grafting of itaconic acid (IA) to produce [PP/LDPE]‐g‐IA in the course of reactive extrusion. To analyze the structural features of the [PP/LDPE]‐g‐IA systems, differential scanning calorimetry and relaxation spectrometry techniques were used. The data were indicative of the incompatibility of PP and LDPE in the [PP/LDPE]‐g‐IA systems on the level of crystalline phases; however, favorable interactions were observed within the amorphous phases of the polymers. Because of these interactions, the crystallization temperature of PP increased by 5–11°C, and that of LDPE increased by 1.3–2.7°C. The rapprochement of their glass‐transition temperatures was observed. The single β‐relaxation peak for the [PP/LDPE]‐g‐IA systems showed that compatibility on the level of structural units was responsible for β relaxation in the homopolymers used. Variations in the ratios of the polymers in the [PP/LDPE]‐g‐IA systems led to both nonadditive and complex changes in the viscoelastic properties as well as mechanical characteristics for the composites. Additions of up to 5 wt % PP strengthened the [PP/LDPE]‐g‐IA blended systems between the glass‐transition temperatures of LDPE and PP. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1746–1754, 2006     

NO decomposition and reduction by C3H6 over transition metal oxides supported on MgF2

The monooxides copper, manganese, molybdenum and chromium catalysts supported on MgF₂ were tested in NO decomposition and reduction by propene. The effect of the oxides content, time on stream and O₂ concentration in reaction mixture during NO reduction on their catalytic activity was investigated. All the catalysts showed the optimum active phase concentration corresponding to 2–4 wt.% of the metal. For the best copper catalyst an effect of introduction of another oxide (manganese or chromium oxide) on the catalytic performance was studied. The double copper-manganese oxide sample containing 2 wt.% Cu and 4 wt.% Mn was proved to ensure the best catalytic performance.     

Effects of ceramic-based CrN,TiN, and AlCrN interlayers on wear and friction behaviors of AlTiSiN+TiSiN PVD coatings

In this study, the wear and friction behavior of cathodic arc physical vapor deposited AlTiSiN+TiSiN coatings on H13 tool steels were investigated by using CrN, TiN and AlCrN interlayers with tribometer tests both under unlubricated and boundary lubricated conditions. 6 mm alumina balls were used as counter surfaces to test ceramic hard coatings. Surface coatings were characterized through nanoindentation, scanning electron microscopy coupled with an energy-dispersive X-ray spectrometer (SEM/EDXS), optical profilometry, and atomic force microscopy (AFM) techniques. The results showed that especially AlTiSiN+TiSiN coating with TiN interlayer resulted in a much more enhanced tribological performance of the tool steels at both unlubricated and the boundary lubricated conditions even at elevated contact pressures.     

Dielectric films fabricated in plasma as passivation of 4H-SiC Schottky diodes

In this report, we propose Al₂O₃ and AlN films as passivation for high-voltage SiC Schottky barrier diodes. A reactive pulse plasma enhanced chemical vapour deposition method is used to form the layers. The comparison between the Schottky barrier diodes with and without passivation shows the effectiveness of Al₂O₃ layer on the reverse current decrease as a result of the surface states reduction.     

Current control for the smoothing of torque in a single-phase permanent-magnet disc motor using 3-D FEM

In this paper, a new disc-type single-phase permanent-magnet motor with a salient pole stator is considered. Due to a particular configuration of the magnets on the rotor disc, the motor develops a starting torque. It also is capable of producing a constant, nearly smooth torque by modifying the current waveform. To determine the required current waveform, the 3-D finite element field model (FEM) is used. To control the current in order to minimize the torque ripple, the field-circuit model of the motor was developed, including the inverter topology.     

Parallel hybrid metaheuristics for the flexible job shop problem

A parallel approach to flexible job shop scheduling problem is presented in this paper. We propose two double-level parallel metaheuristic algorithms based on the new method of the neighborhood determination. Algorithms proposed here include two major modules: the machine selection module refer to executed sequentially, and the operation scheduling module executed in parallel. On each level a metaheuristic algorithm is used, therefore we call this method meta²heuristics. We carry out a computational experiment using Graphics Processing Units (GPU). It was possible to obtain the new best known solutions for the benchmark instances from the literature.     

The notion of diversity in graphical entity summarisation on semantic knowledge graphs

Given an entity represented by a single node q in semantic knowledge graph D, the Graphical Entity Summarisation problem (GES) consists in selecting out of D a very small surrounding graph S that constitutes a generic summary of the information concerning the entity q with given limit on size of S. This article concerns the role of diversity in this quite novel problem. It gives an overview of the diversity concept in information retrieval, and proposes how to adapt it to GES. A measure of diversity for GES, called ALC, is defined and two algorithms presented, baseline, diversity-oblivious PRECIS and diversity-aware DIVERSUM. A reported experiment shows that DIVERSUM actually achieves higher values of the ALC diversity measure than PRECIS. Next, an objective evaluation experiment demonstrates that diversity-aware algorithm is superior to the diversity-oblivious one in terms of fact selection. More precisely, DIVERSUM clearly achieves higher recall than PRECIS on ground truth reference entity summaries extracted from Wikipedia. We also report another intrinsic experiment, in which the output of diversity-aware algorithm is significantly preferred by human expert evaluators. Importantly, the user feedback clearly indicates that the notion of diversity is the key reason for the preference. In addition, the experiment is repeated twice on an anonymous sample of broad population of Internet users by means of a crowd-sourcing platform, that further confirms the results mentioned above.     

Rheological Model for Simulation of Hot rolling of New Generation Steel Strips for Automotive Applications

The main objective of this paper is the development of a rheological model for automotive steels for the conditions of hot strip rolling and implementation of this model in a finite element program is. Three types of steels were investigated, IF, dual phase and TRIP steel. Plastometric tests were performed on a Gleeble 3800 simulator for the temperature range 850‐1200°C and strain rates 3‐150 s^?1. Inverse analysis was applied to eliminate the influence of disturbances occurring in the plastometric tests and to determine the real flow stress of the material. The coefficients in the flow stress equation were evaluated and this equation was implemented in the FEM code as the constitutive law. The model was validated by comparison of measured and calculated loads in the compression tests and by strip rolling experiments conducted in the laboratory mill. Validation confirmed a good predictive capability of the rheological model.