Conversion of C8 aromatics and n-pentane over Ga2O3/HZSM-5 mechanically mixed catalysts

Ga₂O₃/HZSM-5 catalysts prepared as intimate physical mixtures of Ga₂O₃ with HZSM-5 have been studied for the conversion of C₈ aromatics and the aromatization of n-pentane. Hydrogen reduction of the mechanical mixture is a necessary step in the formation of an active catalyst and the reduction process has been characterized by IR spectroscopy. Reduced materials exhibit superior activity and selectivity compared to mechanical mixtures which have not be reduced.     

Physicochemical Interactions in Systems Formed by Trivalent REM with Group IVp Elements. Part 2. Phase Diagrams

A major aspect is considered of the physicochemical interaction in binary systems formed by REM with group IV p elements, namely the phase diagrams. The general regularities and the differences between these phase diagrams are considered for REM – X systems (X = Si, Ge, Sn, and Pb), particularly the relationship between the phase diagram topology and the crystallochemistry of the compounds formed. A comparison is performed for predicted and experimentally constructed phase diagrams.     

Transforming arbitrary tables into logical form with TARTAR

The tremendous success of the World Wide Web is countervailed by efforts needed to search and find relevant information. For tabular structures embedded in HTML documents, typical keyword or link-analysis based search fails. The Semantic Web relies on annotating resources such as documents by means of ontologies and aims to overcome the bottleneck of finding relevant information. Turning the current Web into a Semantic Web requires automatic approaches for annotation since manual approaches will not scale in general. Most efforts have been devoted to automatic generation of ontologies from text, but with quite limited success. However, tabular structures require additional efforts, mainly because understanding of table contents requires the comprehension of the logical structure of the table on the one hand, as well as its semantic interpretation on the other. The focus of this paper is on the automatic transformation and generation of semantic (F-Logic) frames from table-like structures. The presented work consists of a methodology, an accompanying implementation (called TARTAR) and a thorough evaluation. It is based on a grounded cognitive table model which is stepwise instantiated by the methodology. A typical application scenario is the automatic population of ontologies to enable query answering over arbitrary tables (e.g. HTML tables).     

A Computer-Aided System for Design of Drainage Facilities in Surface Mining

Abstract.   Drainage systems in large surface mines are designed to accomplish three basic objectives: keeping working conditions dry, stable and safe; lowering hydrostatic pressure and increasing the effective stress of soil to improve slope stability; and ensuring pit floor workability. This can be achieved with drainage facilities that include channels, water collection sumps, and pump stations. We report the development of a computer-aided system called Dewatering of Open Pit Mines (DEWOP), which can assist open pit mine designers to solve water-related problems. The system was developed in a Visual Basic object programming language, taking advantage of multi-user, open database connectivity, such as Microsoft Access, for storage and processing of information. In tests at coal and copper surface mines, it reduced drainage facilities costs by 8%.     

Self-regulated Complexity in Neural Networks

Recordings of spontaneous activity of in vitro neuronal networks reveal various phenomena on different time scales. These include synchronized firing of neurons, bursting events of firing on both cell and network levels, hierarchies of bursting events, etc. These findings suggest that networks’ natural dynamics are self-regulated to facilitate different processes on intervals in orders of magnitude ranging from fractions of seconds to hours. Observing these unique structures of recorded time-series give rise to questions regarding the diversity of the basic elements of the sequences, the information storage capacity of a network and the means of implementing calculations. Due to the complex temporal nature of the recordings, the proper methods of characterizing and quantifying these dynamics are on the time–frequency plane. We thus introduce time-series analysis of neuronal network’s synchronized bursting events applying the wavelet packet decomposition based on the Haar mother-wavelet. We utilize algorithms for optimal tiling of the time–frequency plane to signify the local and global variations within the sequence. New quantifying observables of regularity and complexity are identified based on both the homogeneity and diversity of the tiling (Hulata et al., 2004, Physical Review Letters 92: 198181–198104 ). These observables are demonstrated while exploring the regularity–complexity plane to fulfill the accepted criteria (yet lacking an operational definition) of Effective Complexity. The presented question regarding the sequences’ capacity of information is addressed through applying our observables on recorded sequences, scrambled sequences, artificial sequences produced with similar long-range statistical distributions and on outputs of neuronal models devised to simulate the unique networks’ dynamics.     

Asymptotic analysis of temporal-difference learning algorithms with constant step-sizes

The mean-square asymptotic behavior of temporal-difference learning algorithms with constant step-sizes and linear function approximation is analyzed in this paper. The analysis is carried out for the case of discounted cost function associated with a Markov chain with a finite dimensional state-space. Under mild conditions, an upper bound for the asymptotic mean-square error of these algorithms is determined as a function of the step-size. Moreover, under the same assumptions, it is also shown that this bound is linear in the step size. The main results of the paper are illustrated with examples related to M/G/1 queues and nonlinear AR models with Markov switching. Editor: Robert Schapire     

Thermodynamics of Interaction of Rare-Earth Metals with d-Metals. The Scandium ― Iron System

Gibbs free energies, enthalpies, and entropies of formation of the compounds ScFe₂ and Sc₂₉Fe₆ are found by measuring the emf of galvanic cells in the range 720-1030 K. The nature of interaction in Fe REM binary systems is analyzed. Scandium is shown to behave like a 3d-metal during interaction with iron.     

Optimization methods of parallel execution of numerical programs in the LuNA fragmented programming system

The organization of high-performance execution of a fragmented program has encountered with the problem of choosing of an acceptable way of its execution. The potentialities of optimizing the execution at the stages of fragmented program development, compilation and execution are considered. The methods and algorithms of such an optimization are proposed to be included into the LuNA fragmented programming language, compiler, generator and run-time system.     

Design and performance of asymmetric supported membranes for oxygen and hydrogen separation

Producing syngas and hydrogen from biofuels is a promising technology in the modern energy. In this work results of authors’ research aimed at design of supported membranes for oxygen and hydrogen separation are reviewed. Nanocomposites were deposited as thin layers on Ni–Al foam substrates. Oxygen separation membranes were tested in CH₄ selective oxidation/oxi-dry reforming. The hydrogen separation membranes were tested in C₂H₅OH steam reforming. High oxygen/hydrogen fluxes were demonstrated. For oxygen separation membranes syngas yield and methane conversion increase with temperature and contact time. For reactor with hydrogen separation membrane a good performance in ethanol steam reforming was obtained. Hydrogen permeation increases with ethanol inlet concentration, then a slight decrease is observed. The results of tests demonstrated the oxygen/hydrogen permeability promising for the practical application, high catalytic performance and a good thermochemical stability.     

Spontaneous Raman spectra of the crystalline, molten and vitreous rare-earth oxyorthosilicates

The polarized Raman spectra of Lu₂SiO₅ (LSO) and Gd₂SiO₅ (GSO) have been measured. The symmetries of the vibrational modes in the LSO and GSO Raman spectra were determined with using the group-theory calculations. Evaporation of SiO₂ from the LSO crystal at annealing above 2100 K and from the LSO melt was determined with High Temperature Raman Spectroscopy technique. It was found, that invert glasses with the LSO and GSO compositions could be synthesized by quick quenching their melts. The structure of these glasses was studied by means of the Raman spectroscopy data.