Games with forbidden situations. Models with soft constraints

The methods of modeling conflict situations are systematized and illustrated, in which the possibilities of each of the sides can depend on the actions of partners. Conflicts are considered in which the disturbance of constraints is possible, but undesirable for one or a few players.     

Many-step two-person games with a fixed sequence of moves under aggregated information on partner’s choice

A many-step two-person game is studied with a fixed sequence of moves under aggregated information on every move at the decision making instant and on the choice of player 2 at the current move. Player 1, knowing this information at every step i, first chooses a strategy x_i(·) = (x₁(·),...,x_n(·)), i = , and informs it for n moves to player 2 at the beginning of the game. His maximal guaranteed result and the corresponding optimal (-optimal) strategy are determined. Such games under complete (nonaggregated) information are formulated and a compact expression for the strategy of player 1 is derived.Translated from Avtomatika i Telemekhanika, No. 2, 2005, pp. 108–114.Original Russian Text Copyright © 2005 by Aliev, Kononenko.This work was supported by the Russian Foundation for Basic Research, project no. 99-01-00791.     

Web user profiles with time-decay and prototyping

User profiling represents an important initial step in personalizing web services and in building recommendation systems. Non-invasive profiling methods monitor users’ behavior and infer interest profiles from their past actions. Most existing profiling methods, which relate the users’ interests to a given ontology, consider only the user’s past actions when calculating his/her profile. The profiling algorithms use a time-decay function for users’ past actions to adapt the profile to shifts in the user’s interests over time. In our work, we propose a hybrid method that combines time-decay and profile correction using prototype profiles. The additional profile correction step considers the interests of similar users and expands the interest scores beyond the concepts detected in the user’s past actions, which facilitates faster profile adaptation to the user’s new interests. In our experimental work, we experimented extensively with two real data sets: data of an online advertising network and student data in an online e-learning environment. We measured the quality of the computed user profiles by correlating them to users’ future actions. Experiments revealed that it is crucial to build the user’s profile using a large number of events from his/her past and to update the profile regularly. When we are unable to do so, the profile correction can be used to keep the quality of the profile from dropping too low. The results show that our method significantly outperforms existing ontological profiling methods.     

Wear of high-fired periclase-spinel refractories in the roof of a double-bath steel-melting furnace

Conclusions Periclase-spinel products prepared from magnesite powders which are pure in chemical composition and beneficiated Kempirsaisk chromite possess an increased resistance (30% higher than in ordinary periclase-spinel brick) during service in the roof of a double-bath steel-melting furnace, operating with oxygen blow in the bath. Their wear in general occurs as a result of the fusion of the working surface. The mechanism of this wear is explained by the metasomatic processes which lead almost to complete replacement of the periclase and chrome-spinel by ferritic spinels.The increase in the resistance of the experimental periclase—spinel refractories is helped by the structure with the direct bond between the grains which retards the access of silicates and slags inside the textural elements. This exerts a favorable influence on the change in structure of the refractory during service, especially in the transition zone in which additional sintering and crack formation leading to scaling of the experimental refractory hardly develops.On the basis of the results of the research we recommend that refractory enterprises set up various technological production lines for making periclase-spinel products from pure Satkinsk magnesite powders (94–96% magnesium oxide) and beneficiated Kempirsaisk chromite (59–60% chromium oxide) using high-temperature firing in a tunnel klin. The use of high fired periclase-spinel products with a direct bond between the grains would increase the resistance of the roofs of metallurgical furnaces operating with the use of oxygen and increasing their outputs.Translated from Ogneupory, No. 5, pp. 28–33, May, 1973.     

High-Temperature Compatibility of Al–Rare Earth Alloys with Titanium Carbide

The wetting of titanium carbide by molten Al–rare earth alloys was studied. The physicochemical properties of the alloys were correlated with the contact angle and the carbon and oxygen affinities of the substrate and alloy. The properties of the alloys were investigated as a function of composition. The phase relations in the Al-rich corners of the Al–Y and Al–Nd phase diagrams were refined using viscosity data. The x-ray microanalysis and Auger electron spectroscopy data were used to assess the melt structure, adsorption behavior of the melt components at the liquid–gas and liquid–solid interfaces, interfacial area, and composition of the transition layer. The introduction of rare-earth additions into Al was found to reduce the temperature at which good adhesion to TiC can be achieved by 100–200 K.     

Oxidation of Powdered Alloys of Aluminum and Cerium during Heating in Air

The effect of cerium on the oxidation of powdered alloys of aluminum and cerium during heating in air at temperatures up to 1773 K was studied using derivatography, xray phase analysis, and thermal desorption of argon. It is established that the rate and completeness of the oxidation of aluminum increase if it is alloyed with cerium. The effect of cerium is due to its polyvalence, high reactivity, and surface activity toward aluminum. Structural and phase nonuniformities that arise during the growth of oxide phases on the surface of oxidized particles of the alloys enhance the interaction of these particles with air oxygen. It is shown that the assumptions that the surfaces of the alloys have a micrononuniform structure and are enriched with CeAl₂ and CeAl₄ groups are valid.     

4-Keto-bacteriorhodopsin films as a promising photochromic and electrochromic biological material

Photochromic and electrochromic spectral properties of 4-keto-bacteriorhodopsin (4-keto-BR) embedded in a polymer matrix were studied. The light-induced spectral changes were found to be similar to those for 4-keto-BR in suspension, but the duration of the photocycle is substantially longer (up to ten of h). Application of a constant electric field induces a bathochromic shift of the main absorption band, the amplitude of the field-induced spectral changes, showing a quadratic dependence on the field strength. Polymer films containing bacteriorhodopsin analogs show promise as new spectrally-selective photochromic and electrochromic materials.