Special Important Aspects of the Thomson Effect

A comprehensive study of the mechanisms of heating and cooling originating from an electrical current in semiconductor devices is reported. The variation in temperature associated with the Peltier effect is not related to the presence of heat sources and sinks if the heat flux is correctly determined. The Thomson effect is commonly regarded as a heat source/sink proportional to the Thomson coefficient, which is added to the Joule heating. In the present work, we will show that this formulation of the Thomson effect is not sufficiently clear. When the heat flux is correctly defined, the Thomson heat source/sink is proportional to the Seebeck coefficient. In the conditions in which the Peltier effect takes place, the temperature gradient is created, and, consequently, the Thomson effect will occur naturally.     

Binary monkey algorithm for approximate packing non-congruent circles in a rectangular container

A Packing problem consists in the best arrangement of several objects inside a bounded area named as the container. This arrangement must fulfill with technological constraints, for example, objects should not be overlapping. Some packing models for circular objects are typically formulated as non-convex optimization problems; where the continuous variables are the coordinates of the objects, so they are limited to not finding optimal solutions. Due to the combinatorial nature in the arrangement of such objects, heuristic methods are being used extensively which combine methods of global search and methods of local exhaustive search of local minima or their approximations. In this paper, we will address the packing problem for non-congruent (different size) circles with the binary version of the monkey algorithm which incorporates a cooperation process and a greedy strategy. We use a rectangular grid for covering the container. Every node in the grid represent potential positions for a circle. In this sense, binary monkey algorithm for the knapsack problem, can be used to solve de 0–1 approximate packing problem for non-congruet circles. The binary monkey problem uses two additional processes of the original monkey algorithm, these two processes are a greedy process and a cooperation processes.

     

The Effect of Titanium, Zirconium and Tin on the Growth of Diatom Synedra Acus and Morphology of Its Silica Valves

The effect of three Group IV metals (titanium, zirconium and tin) on the growth, morphology and chemical composition of the freshwater diatom Synedra acus subsp. radians (Kützing) Skabichevsky was studied and compared with germanium. The elements in their highest oxidation states were introduced into the culture medium in the form of hydroxides. Germanium was found to be toxic at ??5?mol. % of the total Ge-Si content in the culture medium. In the presence of other elements, a slight decrease in the cell division rate was observed independent of the element within 1?C15% content interval. The analysis of the obtained biomass and silica valves revealed the presence of all the added elements within the cells. However, only germanium was incorporated into the valves in considerable amounts. S. acus cultivation with the addition of 5% Group IV elements resulted in cells having the following aberrations in the structure of the silica valves: changes in valve shape, thickening of valves, alterations of the areolae rows, irregularity or absence of the areolae and a decrease in the mechanical strength of valves. Moreover, the effect of Group IV elements on silica formation was simulated in vitro using a synthetic polymer bearing polyamine and phosphate groups found in silaffines (proteins from diatom frustules). The studied elements were observed to provoke the formation of unstable silica particles in solution. We propose that the observed effects of germanium, titanium, zirconium and tin on diatom growth and structure are due to uncontrollable silica condensation.     

Anwendung eines Stranggieß-Simulationsmodells bei Štore Steel – II

This paper represents the elements and the use of the upgraded simulation system, developed in the last half decade for ?tore Steel billet caster. The simulation system is used in the context of the state-of-the-art automation and information of the twenty-five year-old three-strand Concast billet continuous caster for dimensions square 140 and 180 mm with the capacity of 160,000 tons/year. The simulation system is used in the off-line and on-line modes. The off-line mode is used in order to set the proper process parameters and to calculate the temperature field, macrosegregation, and grain structure of the strand. It is also used to calculate the changes in the caster design such as the secondary cooling and the position of the SEN. The on-line model is used in automatic casting control system. The paper represents an update of our BHM publication of 2005 (Application of Continous Casting Simulation at ?tore Steel, BHM, Vol. 150, No. 9, 300–306).     

Automatic categorisation of comments in social news websites

The use of the social web has brought a series of changes in the way how content is created. In particular, social news sites link stories and the different users can comment them. In this paper, we propose a new method based on different features extracted from the text able to categorise the comments. To this end, we use a combination of statistical, syntactic and opinion features and machine-learning classifiers to classify a comment within three different categorisation types: the focus of the comment, the type of information contained in the comment and the controversy level of the comment. We validate our approach with data from ‘Menéame’, a popular Spanish social news site.     

Sources of Fluxes of Energy, Heat, and Diffusion Heat in a Bipolar Semiconductor: Influence of Nonequilibrium Charge Carriers

The equations of energy balance, heat balance, and diffusion heat balance are obtained for a bipolar semiconductor. The roles of nonequilibrium charge carriers and the recombination in the heat transport are established. The expressions for the sources of energy fluxes, heat fluxes, and diffusion heat fluxes are discussed. Both radiative and nonradiative recombinations are studied.     

Mechanical behavior and optical transparency of polyamide 6 of different morphology formed by variation of the pathway of crystallization

The phase composition and supermolecular structure of polyamide 6 (PA 6) melt-crystallized on cooling at different rates or cold-crystallized at different temperatures were characterized and related to the optical transparency, stiffness and the stress–strain behavior. Cold-crystallization results in non-spherulitic formation of γ-mesophase or α-crystals, depending on the maximum annealing temperature. Both mesophase and crystals are of nodular shape. Melt-crystallization at low supercooling leads to formation of lamellar α-crystals and spherulites, while at high supercooling the nodular mesophase is forming. The absence of spherulites in cold-crystallized PA 6 films leads to high see-through clarity which is in contrast to the slowly melt-crystallized samples with opaque appearance. While Young’s modulus and the glass transition temperature increase with increasing crystallinity, for samples of identical crystallinity stiffness is considerably higher if the crystals are of lamellar rather than of nodular shape. The higher glass transition temperature of cold-crystallized PA 6 is related to a higher rigid amorphous fraction than in melt-crystallized samples pointing to a stronger coupling of the amorphous phase to ordered domains.     

Efficiency and fairness in team search with self-interested agents

We consider team-work settings where individual agents incur costs on behalf of the team. In such settings it is frequently the custom to reimburse agents for the costs they incur (at least in part) in order to promote fairness. We show, however, that when agents are self-interested, such reimbursement can result in degradation in efficiency—at times severe degradation. We thus study the relationship between efficiency and fairness in such settings, distinguishing between ex-ante and ex-post fairness. First, we analyze reimbursement policies that reimburse solely based on purchase receipts (as is customary), and show that with such policies the degradation in both efficiency and fairness can be unbounded. We thus introduce two other families of reimbursement policies. The first family guarantees optimal efficiency and ex-ante fairness, but not ex-post fairness. The second family improves (at times) on ex-post fairness, but at the expense of efficiency, thus providing a tradeoff between the two.     

Explaining prediction models and individual predictions with feature contributions

We present a sensitivity analysis-based method for explaining prediction models that can be applied to any type of classification or regression model. Its advantage over existing general methods is that all subsets of input features are perturbed, so interactions and redundancies between features are taken into account. Furthermore, when explaining an additive model, the method is equivalent to commonly used additive model-specific methods. We illustrate the method’s usefulness with examples from artificial and real-world data sets and an empirical analysis of running times. Results from a controlled experiment with 122 participants suggest that the method’s explanations improved the participants’ understanding of the model.