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71.
72.
An emitting, absorbing, and anisotropically scattering plain medium containing a suspension of ZnO particles is considered, in which the particles are directly exposed to high-flux irradiation and undergo shrinkage during their endothermic dissociation into Zn(g) and O2 at above 2100 K. The unsteady energy equation that links the rate of radiative heat transfer to the rate of the chemical reaction is formulated and solved numerically by the finite volume technique and the explicit Euler time-integration scheme. The path-length Monte Carlo method is applied for modeling the radiative transfer within the suspension using the absorption/scattering coefficients and the scattering phase function obtained from the Mie theory. It is found that the particle suspension can be heated rapidly from its initial 300 K to over 1800 K in less than 0.1 s, resulting in a more uniform temperature profile as the reaction progresses, particles shrink, and the suspension becomes optically thinner. The chemical conversion increases with decreasing initial particle diameter and volume fraction due to the efficient radiative absorption. 相似文献
73.
Verification of identity based on the analysis of dynamic signatures is an important problem of biometrics. The effectiveness of the verification significantly increases when the dynamic characteristics of signature (e.g. velocity of the pen) are considered. These characteristics are individual for each user and difficult to imitate. The effectiveness of the verification can be further improved by using partitioning. In this paper we propose a new method which uses partitioning. In our method partitions represent areas of high and low speed of signature and high and low pen?s pressure. All selected partitions are used by our algorithm, but more important in the classification process are these partitions, in which the signatures of the user acquired during training phase are more stable. Moreover, final classification is interpretable. In this paper we present the simulation results of the proposed method for the two databases: SVC2004 and BioSecure Database. 相似文献
74.
75.
Ionic liquids as electrolytes 总被引:5,自引:0,他引:5
Salts having a low melting point are liquid at room temperature, or even below, and form a new class of liquids usually called room temperature ionic liquids (RTIL). Information about RTILs can be found in the literature with such key words as: room temperature molten salt, low-temperature molten salt, ambient-temperature molten salt, liquid organic salt or simply ionic liquid. Their physicochemical properties are the same as high temperature ionic liquids, but the practical aspects of their maintenance or handling are different enough to merit a distinction. The class of ionic liquids, based on tetraalkylammonium cation and chloroaluminate anion, has been extensively studied since late 1970s of the XX century, following the works of Osteryoung. Systematic research on the application of chloroaluminate ionic liquids as solvents was performed in 1980s. However, ionic liquids based on aluminium halides are moisture sensitive. During the last decade an increasing number of new ionic liquids have been prepared and used as solvents. The general aim of this paper was to review the physical and chemical properties of RTILs from the point of view of their possible application as electrolytes in electrochemical processes and devices. The following points are discussed: melting and freezing, conductivity, viscosity, temperature dependence of conductivity, transport and transference numbers, electrochemical stability, possible application in aluminium electroplating, lithium batteries and in electrochemical capacitors. 相似文献
76.
Beata Biaobok Janusz Trawczyski Wodzimierz Mita Mirosaw Zawadzki 《Applied catalysis. B, Environmental》2007,72(3-4):395-403
Ce- or Sr-doped LaCoO3 bulk perovskites were prepared by citric acid method as well as 10 wt.% of LaCoO3 was deposited on alumina carrier stabilized with lanthanum. Properties of prepared materials were characterized by determination of surface area, acid-basic properties and XRD, XPS, TPDO2, H2-TPR measurements as well as catalytic activity and selectivity for ethanol combustion was tested. It was found that substitution of La in LaCoO3 with either Sr or Ce has only small effect on its activity in ethanol combustion. Strontium inserted into LaCoO3 structure increases basic character of the perovskite surface as well as selectivity to acetaldehyde (ACA). Substitution of La with cerium has no effect on the concentration of basic sites and does not affect the selectivity to ACA. Activity of LaCoO3-based catalysts in ethanol combustion and their selectivity to ACA formation can be explained on the basis of the presence of both -oxygen species and sites with basic character on the material surface.
Acid-basic properties of supported LaCoO3 are dominated by acidic character of the carrier. Results of XPS and H2-TPR measurements of LaCoO3 supported on La–Al2O3 suggest that perovskite remains in strong interaction with carrier and probably is partially decomposed. Deposition of perovskite on stabilized carrier significantly increases the rate of ethanol combustion. 相似文献
77.
Changes in transparency and color as well as GHCl values of hard PVC foils exposed to gamma radiation were investigated while using different amounts of the stabilizers ethylene glycol bis-β-aminocrotonate (I), calcium/zinc laurate + epoxy compounds (II), and magnesium/zinc stearate + sorbitol + epoxy compounds (III), and plasticizers dioctyl phthalate (DOP) (IV), dioctyl sebacate (V), propylene glycol polyadipate + octyl alcohol composition (VI), and diisotridecyl phthalate (VII). A strong synergistic effect was observed in systems containing both plasticizer and stabilizer. Best results were obtained for the I + II + IV, I + II + V, and I + III + V systems. 相似文献
78.
Rajmund S. Dybczyński Marta Pyszynska Krzysztof Kulisa Anna Bojanowska-Czajka 《分离科学与技术》2020,55(7):1364-1379
ABSTRACTNew ion interaction chromatographic (IIC) method employing Kromasil 100 C18 column and tetra-n-butylammonium hydroxide (TBAOH) as an ion interaction reagent (IIR) is able to separate yttrium from Rare Earth Elements (REE) as anionic complexes with nitrilotriacetic acid (NTA). New method for the chromatographic determination of Y in REE mixture was devised and validated by the analysis of the certified reference material (CRM). Potential possibilities of the new chromatographic system for larger scale applications including macro-micro events were demonstrated. 相似文献
79.
Szymkowski Maciej Jasiński Piotr Saeed Khalid 《Innovations in Systems and Software Engineering》2021,17(3):309-317
Innovations in Systems and Software Engineering - One of the most important modules of computer systems is the one that is responsible for user safety. It was proven that simple passwords and... 相似文献
80.
Joanna DumańskaKrzysztof Maksymiuk 《Corrosion Science》2002,44(8):1681-1693
Spontaneous charging/discharging processes of polymers: polypyrrole and poly(N-methylpyrrole), doped with perchlorate (anion exchanging PPy and PMPy, respectively) and poly(4-styrenesulphonate) ions (cation exchanging PPy(PSS) and PMPy(PSS)) occurring in aqueous electrolyte solutions were studied using different electrochemical techniques. These reactions (oxidation of the polymer by dissolved oxygen and discharge of the polymer redox capacitance) are usually undesired processes leading to alteration of the charge accumulated in the polymer films. This paper points out that these processes can be significantly limited in polymer bilayers due to effect of charge trapping. 相似文献