Losses of chemical energy in hard-coal energy-utilization exothermic processes

In the sequence of occurrence, these processes are the losses in coal production, processing losses, and the losses in electrical-energy generation. These losses are evaluated.     

A PERMIAN BEACH IN THE ZECHSTEIN DOLOMITES FO WESTERN POLAND: INFLUENCE ON RESERVOIRS

Zechstein ooid grainstones, which have formed a narrow belt (several hundered meters in width) along the basin-facing platform margin, have been greatly affected by fresh-water diagenesis, resulting in contrasting resrvoir characteristics. fresh-water diagenesis, which was related to a beach environment, was closely accompanied by dolomitization; there was competition between the dissolution of aragonitic ooids and their dolomitiztion. Dissolution of aragonitic ooids can produce an excellent intragranular porosity when early diagenetic dolomite cements form prior to dissolution (Kaldi and Gidman, 1982), or it can produce a non-porous fabric of overcompacted deformed "spastoliths". Although burial diagenesis significantly modified the reservoir characteristics of the Zechstein ooid grainstones, a very irregular pattern of early meteoric-related diagenesis is the main reason why discoveries are so unpredictable in the Zechstein.     

Local controllability and minimum energy control of continuous 2-D linear systems with variable coefficients

Necessary and sufficient conditions for the local controllability of continuous 2-D linear systems with variable coefficients are established. The minimum energy control problem is formulated and solved for the 2-D systems.     

Macromonomers by activated polymerization of oxiranes. Synthesis and polymerization

Macromonomers were obtained by cationic polymerization of propylene oxide and epichlorohydrin proceeding by the activated monomer mechanism with hydroxyethyl acrylate as initiator. Up to DP _n ～ 15 for propylene oxide and DP _n ～ 20 for epichlorohydrin, polymerization proceeds as a living process, giving with quantitative yields macromonomers with functionality equal to one, controlled molecular weight and narrow molecular weight distribution (M _wM _n<1.2) free of side products. In the higer molecular weight region, side reactions become increasingly noticeable. Propylene oxide macromonomers undergo radical homopolymerization. Homopolymerization of macromonomer with M _n = 8×10² gives graft copolymers with M _n up to 7.2×10³ in copolymerization with styrene, completely soluble graft copolymers with M _n ～ 2×10⁴ were obtained. Radical copolymerization of epichlorohydrin macromonomers with styrene gives initially soluble products with M _n ～ 6×10⁴ were obtained. Radical copolymerization of epichlorohydrin macromonomers with styrene gives initially soluble products with M_n～ 6×10⁴, which are converted in the later stages into insoluble gels, apparently due to the chain transfer to chloromethly groups of the polyepichlorohydrin chains.     

Eddy current imaging,array sensors and flaw reconstruction

Eddy current imaging is widely accepted as a nondestructive testing technique enabling efficient flaw reconstruction based on much richer and comprehensive data sets than the traditional Lissajous patterns obtained from a single scan. In this paper the essential problems encountered during creation and processing of eddy current images are reviewed. The special role of eddy current transducers in creation of eddy current images is emphasized. The main part of the paper deals with formation and solving of eddy current problems which arise when flaw shapes should be reconstructed. An iterative method for reconstruction of 3D flaw images is proposed and discussed. The relation between reconstruction of the 3-D flaw image and the restoration of its 2-D top view is analysed.     

Filtering of some nonlinear diffusions satisfying the general Bene condition

Under some regularity assumptions and the following generalization of the well-known Bene condition [1]:

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, where F(t,z) = g⁻²(t)∫f(t,z)dz, F_t, F_z, F_zz, are partial derivatives of F, we obtain explicit formulas for the unnormalized conditional density q_t(z, x) α Px_t ε dz| y_s, 0 st, where diffusion x_t on R¹ solves x₀ = x, dx_t = [β(t) + α(t)x_t + f(t, x_t] dt + g(t) dw₁, and observation y_t = ∫_o^th(s)x_s ds + ∫_o^t(s) dw_2t, with w = (w₁, w₂) a two-dimensional Wiener process.     

Segregation in Titanium Dioxide Co‐Doped with Indium and Niobium

This work reports the effect of oxygen activity on surface segregation for TiO₂ co‐doped with two cations, indium and niobium (0.076 at.% In + 0.103 at.% Nb). In this work, we studied the effect of annealing at 1273 K in the gas phase of controlled oxygen activity on surface segregation of both ions. The applied oxygen activity included pure oxygen, p(O₂) = 100 kPa, and argon, p(O₂) = 10 Pa. The segregation‐induced concentration gradients were determined using both secondary ion mass spectrometry and X‐ray photoelectron spectroscopy. The obtained results indicate that annealing of the studied TiO₂ specimens in argon results in cooperative segregation of both ions leading to the formation of a surface structure involving comparative concentrations of both cations. However, annealing in oxygen results in preferential segregation of indium leading to the formation of a In₂TiO₅‐type surface structure. The obtained results are considered in terms of the effect of multicomponent segregation on processing of the surface layer with controlled properties that are desired for specific applications. The present work indicates that oxygen activity may be used as the parameter in surface engineering of the solid solution.     

Electrical conductivity and defect disorder of tantalum‐doped TiO2

The present work reports the electrical properties of polycrystalline Ta‐doped TiO₂ (0.39 at.% Ta) determined in situ at elevated temperatures (1173‐1323 K) in the gas phase of controlled oxygen activity (10^?12 Pa to 10⁵ Pa). The effect of oxygen activity on the electrical conductivity and thermoelectric power of TiO₂ is discussed in terms of defect disorder, including (1) the intrinsic electronic disorder that is governed by electronic compensation in the strongly reducing regime, (2) the extrinsic electronic disorder that is governed by electronic charge compensation in the reducing regime, and (3) the extrinsic ionic disorder that is governed by ionic compensation in the oxidizing regime. It is shown that tantalum ions are incorporated into the titanium sublattice of TiO₂ leading to the formation of donor‐type energy levels. The Arrhenius‐type plot of the electrical conductivity data leads to the determination of the formation enthalpy terms. The obtained results are considered in terms of the effect of tantalum and oxygen activity on the defect disorder and the associated key performance‐related properties in the light‐induced partial water oxidation.     

A study on using data clustering for feature extraction to improve the quality of classification

There is a certain belief among data science researchers and enthusiasts alike that clustering can be used to improve classification quality. Insofar as this belief is fairly uncontroversial, it is also very general and therefore produces a lot of confusion around the subject. There are many ways of using clustering in classification and it obviously cannot always improve the quality of predictions, so a question arises, in which scenarios exactly does it help? Since we were unable to find a rigorous study addressing this question, in this paper, we try to shed some light on the concept of using clustering for classification. To do so, we first put forward a framework for incorporating clustering as a method of feature extraction for classification. The framework is generic w.r.t. similarity measures, clustering algorithms, classifiers, and datasets and serves as a platform to answer ten essential questions regarding the studied subject. Each answer is formulated based on a separate experiment on 16 publicly available datasets, followed by an appropriate statistical analysis. After performing the experiments and analyzing the results separately, we discuss them from a global perspective and form general conclusions regarding using clustering as feature extraction for classification.

     

A Bench‐Scale Study of Conditioning Behaviour in Oil Sands Slurries

Proper conditioning of an oil sand/water slurry is essential for the efficient extraction of bitumen. The conditioning process depends on such variables as ore grade, temperature, mixing intensity, mixing time, and water composition. A technique has been developed in which a microscope and video cameras are used to observe a slurry stirred in a glass cell to evaluate, on a comparative basis, the effect of conditioning parameters on bitumen recovery. Several ores and their blends were studied and found to exhibit large differences in their conditioning behaviour. The method offers the capability of diagnosing ore processability problems and optimizing slurry conditioning.