Hierarchical Estimator

In this paper, a new machine learning solution for function approximation is presented. It combines many simple and relatively inaccurate estimators to achieve high accuracy. It creates – in incremental manner – hierarchical, tree-like structure, adapting it to the specific problem being solved. As most variants use the errors of already constructed parts to direct further construction, it may be viewed as example of boosting – as understood in general sense. The influence of particular constituent estimator on the whole solution’s output is not constant, but depends on the feature vector being evaluated.Provided in this paper are: general form of the metaalgorithm, a few specific, detailed solutions, theoretical basis and experimental results with one week power load prediction for country-wide power distribution grid and on simple test datasets.     

Ordered mesoporous tin oxide and tin phosphate synthesized by nanocasting strategy

Ordered mesoporous tin oxide and tin phosphate were successfully synthesized via two-step nanocasting route. The SBA-15 silica and CMK-3 carbon were used as hard templates. Powder X-ray diffraction, nitrogen adsorption and transmission electron microscopy confirmed hexagonal mesoporous structure of resulted products. Mesoporous tin oxide indicated crystalline walls (cassiterite). The mesoporous products showed considerable catalytic activity in propan-2-ol decomposition. The tin oxide led the dehydrogenation towards acetone, while mesoporous tin phosphate exhibited activity of acid sites resulting in dehydration to propene.     

Axially symmetric problems of heat conduction in a periodically laminated layer with vertical cylindrical hole

The distributions of temperature and heat fluxes in a periodically laminated layer with a vertically located cylindrical hole are obtained approximately within the homogenized model with microlocal parameters. The method of solution is based on the Weber-Orr integral transforms. The effects of geometrical and mechanical parameters of the composite structure on the thermal fields are discussed and presented in graphical form.     

A study on Saccharomyces cerevisiae and Candida utilis cell wall capacity for binding magnesium

The capacity for binding magnesium by bakery's yeast strain Saccharomyces cerevisiae No. 102 (Pure Culture Collection, Faculty Food Technology, Warsaw) and fodder yeast strain Candida utilis (ATCC 9950) was investigated in media supplemented with that element. The capacities of C. utilis (ATCC 9950) and S. cerevisiae (No. 102) biomass for binding magnesium were not statistically different in the first 24 h. In the next 24 h of cultivation the cells of C. utilis (ATCC 9950) were still able to bind magnesium ions, whereas those of S. cerevisiae (No. 102) released a part of previously bound magnesium to the medium. The major part of magnesium bound by the cells of C. utilis (ATCC 9950) was accumulated in cytosole. It was opposite to the cells of bakery yeast S. cerevisiae (No. 102) that accumulated magnesium mainly in the cell wall. The cells of C. utilis (ATCC 9950) yeast were smaller and their cell walls were thinner as compared to those of S. cerevisiae (No. 102) yeast. The thickness of the external mannoprotein layers was similar in both strains analyzed.     

The effects of power characteristics on the heat transfer process in various types of motionless mixing devices

The main objective of this paper is to present the measurement results of the pressure drop and the heat transfer coefficient in the various types of static mixers. The experimental investigations are provided for the explanation of the influence of hydrodynamic conditions on the heat transfer enhancement for different static mixers. Based on the analysis of the experimental database and theoretical considerations, original formulas are proposed for the determination of the power consumption and the heat transfer in various types of motionless mixing devices. In this paper a new criterion is also defined which takes into consideration both the heat transfer process and hydrodynamic conditions. This criterion may be successfully applied to the selection of a static mixer for the heat transfer problems.     

Generalized Thermodynamics of Maximum Work in Finite Time

We consider thermodynamic behaviour of thermal machines founded on kinetic rather than static origins. Their models, which are formulated for finite time transitions, simplify to models of classical thermodynamics in the limiting case of an infinite duration. An extended exergy is derived as a finite-time extension of the classical thermodynamic work delivered from a system of a body and its environment. With this quantity enhanced bounds can be determined for active continuous and cascade processes, in which there is an indirect energy exchange between two sybsystems through the working fluid of an engine, a refrigerator or a heat pump. These bounds refer to systems with finite exchange area or with a finite contact time. An economic framework of this theory is outlined.For both continuous and discrete processes, nonlinear thermodynamic models are derived from a combination of the energy balance and transfer equations. These models serve as constraints in the problem of work optimization. Variational and optimal control approaches are developed which are analogous to those found in analytical mechanics. Variational calculus is used along with some aspect of the canonical transformation theory to maximize work and discuss the role of a finite process intensity and of a finite duration.The optimality of a definite irreversible process for a finite-time transition of a controlled fluid is pointed out as well as a connection between the process duration, optimal dissipation and the optimal process intensity measured in terms of a hamiltonian, a dissipative quantity. It is shown that limits of the classical availability theory should be replaced by stronger limits which are obtained for finite time processes, and which are closer to reality. A hysteretic property of the generalized exergy describes a decrease of the maximum work received from an engine system and an increase of work added to a heat pump system, the features which are particularly important in high-rate regions of thermodynamic processes. For an infinite sequence of infinitesimal thermal machines, an optimal temperature strategy is obtained in the form similar to that known in the theory of simulated annealing.     

Effect of laser radiation upon heat and mass transfer in two-component elastic semitransparent layer

In present paper the effect of the correlation between spectral radiative characteristics of different lasers and absorptive characteristics of laser irradiated two-component elastic semitransparent material upon coupled thermal, diffusive and elastic processes in the layer is examined. Irradiated material is supposed to consist of elastic matrix and gaseous admixture. Investigations are carried out within the model applied early to the study of mentioned coupled processes in the layer subjected to thermal infrared radiation. Calculations were carried out for four different infrared lasers. Peculiarities of heat and admixture mass transfer caused by laser irradiation are established and discussed.     

A role of parameters in RF PA CVD technology of a-C:N:H layers

Results concerning influence of radio-frequency plasma-assisted chemical vapor deposition (RF PA CVD; 13.56 MHz) processing parameters on a-C:N:H layer deposition are presented in this work. The following parameters have been taken into consideration: substrate temperature, plasma RF generator power, composition of reactive gas mixture, gas pressure and time of deposition. A special interest has been focused on the deposition rate as well as on the structure and chemical composition of layers. The layer thicknesses have been measured and deposition rates evaluated. Structure analysis has been performed with application of FT-IR spectroscopy. The obtained results may serve as a basis in the design of the technology of a-C:N:H layers for various applications.     

Sulfur mustard destruction using ozone, UV, hydrogen peroxide and their combination

Numerous methods are used for destruction of sulfur mustard. Oxidation is one of those methods. There have been only limited data concerning application of the advanced oxidation technologies (AOTs) for mustard destruction available before. In this study sulfur mustard oxidation rate depending on kind of the oxidative system and process parameters used was assessed using selected AOT. The following were selected for mustard oxidation: ozone (O(3)), UV light (UV), hydrogen peroxide (H(2)O(2)); double systems: UV/O(3), UV/H(2)O(2), and O(3)/H(2)O(2); a triple system: O(3)/H(2)O(2)/UV and Fenton reaction. Effectiveness of the selected AOT methods has been evaluated and the most suitable one for mustard destruction was chosen. Using ozone in various combinations with hydrogen peroxide and UV radiation mustard can be destroyed much quicker comparing to the classical oxidizers. Fast mustard oxidation (a few minutes) occurred in those systems where ozone alone was used, or in the following combinations: O(3)/H(2)O(2), O(3)/UV and O(3)/H(2)O(2)/UV. When those advanced oxidation technologies are used, mustard becomes destroyed mainly in course of the direct oxidation with ozone, and reactions of mustard with radicals formed due to ozone action play a secondary role. Rate of sulfur mustard oxidation in the above mentioned ozone-containing oxidative systems decreases with pH value increasing from 2 to 12. Only when pH value of reaction solutions is close to pH 5, mustard oxidation rate is minimal, probably due to "disappearance" of radicals participating in oxidation in this pH. Sulfur mustard can be most effectively destroyed using just ozone in pH 7. In that case mustard destruction rate is only slightly lower than the rate achieved in optimal conditions, and the system is the simplest.     

Investigation into the activity of heteropolyacids towards the oxygen reduction reaction on PEMFC cathodes

A total of 18 heteropolyacids (HPAs) were investigated to determine their activity as non-Pt oxygen reduction reaction (ORR) catalysts in polymer electrolyte membrane fuel cell cathodes (PEMFCs). Polarization curves, cyclic voltammetry and impedance spectroscopy determined that, of the HPAs tested, only molybdenum based HPAs are active for the ORR and that vanadium substitutions improved the activity. The reduction potentials of the HPAs in the fuel cell environment were determined by cyclic voltammetry. This showed that no activity is seen above 0.55 V, as the catalysts must first be reduced in situ by 4e⁻ before the HPA can reduce oxygen. The potential at which the HPA can be reduced has been determined to be the limiting factor when using these catalysts for ORR in PEMFCs. Power densities of 67 mW/cm² at 0.2 V were obtained using H₅PMo₁₀V₂O₄₀. Molybdenum based HPAs were covalently bonded to the carbon achieving mass loadings 3× that obtained through adsorption. Using this approach catalyst, performance was improved to 86 mW/cm² at 0.2 V. The increased loadings did not significantly increase the potentials at which the HPA becomes active for the ORR. We were able to show that MEA degradation, as measured by F⁻ emission rates, using these catalysts are reduced during accelerated testing protocols.