Upgrading of gas oils: the HDS kinetics of dibenzothiophene and its derivatives in real gas oil

The hydrodesulphurization (HDS) of dibenzothiophene (DBT), 4-methyl dibenzothiophene (4 M-DBT), 4,6-dimethyl dibenzothiophene (4,6 DM-DBT) and 4,6-diethyl dibenzothiophene (4,6 DE-DBT) as real gas oil components on NiMo/Al₂O₃ catalyst was investigated. On the basis of the first order rate constants of HDS of the individual sulphur compounds reactivities of the investigated compounds decreased in the order DBT ≫ 4 M-DBT > 4,6 DE-DBT ≈ 4,6 DM-DBT. Apparent activation energies of HDS of above sulphur compounds increased from 80.0 to 120.5 kJ/mol.     

Prediction of emerging technologies based on analysis of the US patent citation network

The network of patents connected by citations is an evolving graph, which provides a representation of the innovation process. A patent citing another implies that the cited patent reflects a piece of previously existing knowledge that the citing patent builds upon. A methodology presented here (1) identifies actual clusters of patents: i.e., technological branches, and (2) gives predictions about the temporal changes of the structure of the clusters. A predictor, called the citation vector, is defined for characterizing technological development to show how a patent cited by other patents belongs to various industrial fields. The clustering technique adopted is able to detect the new emerging recombinations, and predicts emerging new technology clusters. The predictive ability of our new method is illustrated on the example of USPTO subcategory 11, Agriculture, Food, Textiles. A cluster of patents is determined based on citation data up to 1991, which shows significant overlap of the class 442 formed at the beginning of 1997. These new tools of predictive analytics could support policy decision making processes in science and technology, and help formulate recommendations for action.     

Inhomogeneous softening during annealing of ultrafine-grained silver processed by HPT

The softening in ultrafine-grained silver processed by high-pressure torsion (HPT) was studied during annealing using differential scanning calorimetry (DSC). Two separate exothermic peaks were observed in the DSC thermogram of the HPT-processed sample. It is shown that the first and the second peaks are related to the recrystallization of the middle volume and the surface regions of the HPT-processed disk, respectively. Therefore, a very inhomogeneous sandwich-like microstructure develops during annealing with a soft interior and hard surface layers. The lower thermal stability of the middle region appears to be related to the stronger twinning activity since the twinned volumes can act as nuclei for recrystallized grains. The higher twin-fault probability in the interior is attributed to the larger strain due to the outflow of material between the anvils of the HPT facility during quasi-constrained processing.     

Distributed high dimensional information theoretical image registration via random projections

Information theoretical measures, such as entropy, mutual information, and various divergences, exhibit robust characteristics in image registration applications. However, the estimation of these quantities is computationally intensive in high dimensions. On the other hand, consistent estimation from pairwise distances of the sample points is possible, which suits random projection (RP) based low dimensional embeddings. We adapt the RP technique to this task by means of a simple ensemble method. To the best of our knowledge, this is the first distributed, RP based information theoretical image registration approach. The efficiency of the method is demonstrated through numerical examples.     

A 2 MV Van de Graaff accelerator as a tool for planetary and impact physics research

Investigating the dynamical and physical properties of cosmic dust can reveal a great deal of information about both the dust and its many sources. Over recent years, several spacecraft (e.g., Cassini, Stardust, Galileo, and Ulysses) have successfully characterised interstellar, interplanetary, and circumplanetary dust using a variety of techniques, including in situ analyses and sample return. Charge, mass, and velocity measurements of the dust are performed either directly (induced charge signals) or indirectly (mass and velocity from impact ionisation signals or crater morphology) and constrain the dynamical parameters of the dust grains. Dust compositional information may be obtained via either time-of-flight mass spectrometry of the impact plasma or direct sample return. The accurate and reliable interpretation of collected spacecraft data requires a comprehensive programme of terrestrial instrument calibration. This process involves accelerating suitable solar system analogue dust particles to hypervelocity speeds in the laboratory, an activity performed at the Max Planck Institut fu?r Kernphysik in Heidelberg, Germany. Here, a 2 MV Van de Graaff accelerator electrostatically accelerates charged micron and submicron-sized dust particles to speeds up to 80 km s(-1). Recent advances in dust production and processing have allowed solar system analogue dust particles (silicates and other minerals) to be coated with a thin conductive shell, enabling them to be charged and accelerated. Refinements and upgrades to the beam line instrumentation and electronics now allow for the reliable selection of particles at velocities of 1-80 km s(-1) and with diameters of between 0.05 μm and 5 μm. This ability to select particles for subsequent impact studies based on their charges, masses, or velocities is provided by a particle selection unit (PSU). The PSU contains a field programmable gate array, capable of monitoring in real time the particles' speeds and charges, and is controlled remotely by a custom, platform independent, software package. The new control instrumentation and electronics, together with the wide range of accelerable particle types, allow the controlled investigation of hypervelocity impact phenomena across a hitherto unobtainable range of impact parameters.     

Development Pathways of Large Housing Estates in Post-socialist Cities: An International Comparison

Large housing estates in former state-socialist countries had been hardly affected by social erosion before the political changes. However, the emergence of new, capitalist forms of housing after 1990 started to endanger the position of large housing estates on the local housing market. The question was repeatedly raised in the literature about whether large housing estates of post-socialist cities would experience physical decay and social downgrading similar to the West. This paper investigates the socio-economic differentiation of large housing estates in the former state-socialist countries using a case study approach. Housing satisfaction and mobility of residents in four post-socialist housing estates were analysed through a standardised household survey. Empirical data confirm that despite their similar physical appearance, the attitude of people towards large housing estates and their position on the local housing market vary significantly. The authors conclude that even though socialist large housing estates are affected by social downgrading, nevertheless they represent relative social stability and can offer affordable housing to people who are at the start of their housing career.     

Minimal equational representations of recognizable tree languages

 A tree language is congruential if it is the union of finitely many classes of a finitely generated congruence on the term algebra. It is well known that congruential tree languages are the same as recognizable tree languages. An equational representation is an ordered pair (E, P) , where E is either a ground term equation system or a ground term rewriting system, and P is a finite set of ground terms. We say that (E, P) represents the congruential tree language L which is the union of those ?^* _E -classes containing an element of P, i.e., for which L=⋃{[p]_? ^* _E ∣p∈P}. We define two sorts of minimality for equational representations. We introduce the cardinality vector (∣E∣, ∣P∣) of an equational representation (E, P). Let ? _l and ? _a denote the lexicographic and antilexicographic orders on the set of ordered pairs of nonnegative integers, respectively. Let L be a congruential tree language. An equational representation (E, P) of L with ? _l -minimal (? _a -minimal) cardinality vector is called ? _l -minimal (? _a -minimal). We compute, for an L given by a deterministic bottom-up tree automaton, both a ? _l -minimal and a ? _a -minimal equational representation of L. Received: 27 July 1994/5 October 1995     

Variants of top-down tree transducers with look-ahead

In this article we consider deterministic and strongly deterministic top-down tree transducers with regular look-ahead, with regular check, with deterministic top-down look-ahead, and with deterministic top-down check. We compare the transformational power of these tree transducer classes by giving a correct inclusion diagram of the tree transformation classes induced by them. Along with the comparison we decompose some of the examined classes into simpler classes and we introduce the concept of the deterministic top-down tree automata with deterministic top-down look-ahead. We show that these recognizers recognize a tree language class which is strictly between the class of regular tree languages and the class of tree languages recognizable by deterministic top-down tree automata. We also study the closure properties of the examined tree transformation classes. We show that some classes are closed under composition while others, for example the class of tree transformations induced by deterministic top-down tree transducers with deterministic top-down look-ahead, are not.