60 research outputs found

    Enhancement of CO2 conversion by counterflow gas quenching of the post-discharge region in microwave plasma sustained by gyrotron radiation

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    A threefold increase in the CO2 conversion and energy efficiency due to the cooling of the post-discharge region by the counter gas flow has been achieved in the plasma of an atmospheric pressure discharge supported by microwave radiation of a gyrotron with a frequency of 24 GHz in a carbon dioxide gas flow. The role of convective heat transfer in the process of gas mixture cooling in the post-discharge region has been experimentally demonstrated. At nitrogen quench gas flow of 4.5 l/min, the CO2 conversion was 23.8 % and energy efficiency was 19.7 %. The possibility of using the flow of cooled gas mixture (CO2,CO,O2) taken from the reactor as quenching gas has been experimentally demonstrated, which made it possible to achieve a CO2 conversion degree of 23.4 % and to eliminate the problem of dilution of reaction products by third-party gases. Based on numerical modeling, it is shown that the increase in the conversion degree upon the destruction of the plasma torch structure is due to the increase in heat exchange with the surrounding atmosphere, and the efficiency of this destruction is determined by the velocity and density of quenching gas.Comment: 20 pages, 14 pages, submitted to the Journal of Energy Chemistry 28.11.202

    High-pressure cryogelation of nanosilica and surface properties of cryosilicas

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    Silica cryogels (cryosilicas) in a powder state were synthesized with different concentrations of fumed silica A-300 (CA-300 = 5-20 wt.%), sonicated in aqueous suspension, then frozen at -14 oC at different pressures in a high-pressure stainless steel reactor (a freezing bomb), and dried in air at room temperature. To analyze the effects of low temperature and high pressure, samples were also prepared at -14 oC or room temperature and standard pressure. The structural and adsorption properties of the powder materials were studied using nitrogen adsorption, high-resolution transmission electron microscopy, infrared spectroscopy, thermogravimetry, low-temperature 1H NMR spectroscopy and thermally stimulated depolarization current. The structural, textural, adsorption and relaxation characteristics of high-pressure cryogel hydrogels and related dried powders are strongly dependent on the silica content in aqueous suspensions frozen at 1, 450 or 1000 atmospheres and then dried. The largest changes are found with CA-300 = 20 wt.% which are analyzed with respect to the interfacial behavior of nonpolar, weakly polar and polar adsorbates using low temperature 1H NMR spectroscopy

    Wave polynomials, transmutations and Cauchy's problem for the Klein-Gordon equation

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    We prove a completeness result for a class of polynomial solutions of the wave equation called wave polynomials and construct generalized wave polynomials, solutions of the Klein-Gordon equation with a variable coefficient. Using the transmutation (transformation) operators and their recently discovered mapping properties we prove the completeness of the generalized wave polynomials and use them for an explicit construction of the solution of the Cauchy problem for the Klein-Gordon equation. Based on this result we develop a numerical method for solving the Cauchy problem and test its performance.Comment: 31 pages, 8 figures (16 graphs

    СУЧАСНІ АСПЕКТИ МЕДИКО-СОЦІАЛЬНОЇ РЕАБІЛІТАЦІЇ ІНВАЛІДІВ - УЧАСНИКІВ АНТИТЕРОРИСТИЧНОЇ ОПЕРАЦІЇ

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    Purpose: to search the needs of ATO participants in medical and social rehabilitation measures at the main disabling pathology.Materials and Methods. The needs of ATO participants in medical and social rehabilitation measures are calculated on the basis of analysis of 3947 individual rehabilitation programs (IRP) developed by rehabilitation specialists of medical and social expert commissions in 19 regions of Ukraine with the main disabling pathology (after the consequences of trauma and somatic pathology). Methods: expert evaluations, statistical-mathematical, meta-analysis according to the data of medical and expert documentation and IPR, analytical and logical.Results. The obtained data testify to the availability of complex diverse needs of disabled patients-participants ATO in medical and social rehabilitation activities (medical, psychological, professional, social, technical means of rehabilitation, medical devices) the volume of which varies depending on the type of services, age, severity of disability, pathology.Conclusion. When forming individual programs of rehabilitation doctors of medical and social expert commission underestimate the role of services in professional, social, technical means of rehabilitation in removing limitation of life, improving the quality of life of the disabled, their social adaptation. This needs to be improved by the work of the medical and social expert commissions.Мета роботи – визначення потреб інвалідів-учасників АТО в заходах медико-соціальної реабілітації при основній інвалідизуючій патології.Матеріали та методи. Розрахована потреба інвалідів-учасників АТО в заходах медико-соціальної реабілітації на підставі аналізу 3947 індивідуальних програм реабілітації (ІПР), які розроблені реабілітологами медико-соціальних експертних комісій (МСЕК) 19 областей України при основній інвалідизуючій патології (наслідках бойових травм та соматичної патології). Використані методи: експертних оцінок, статистично-математичний, мета-аналіз за даними медико-експертної документації та ІПР, аналітико-логічний.Результати дослідження. Отримані дані свідчать про наявність комплексних різноманітних потреб інвалідів-учасників АТО в заходах медико-соціальної реабілітації (медичної, психологічної, професійно-трудової, соціальної, технічних засобах реабілітації та виробах медичного призначення), обсяг яких відрізняється в залежності від виду послуг, віку, важкості інвалідності, патології.Висновки. При формуванні ІПР має місце недооцінка ролі послуг з професійної, соціальної реабілітації, технічних засобів реабілітації в усуненні обмежень життєдіяльності, покращенні якості життя інвалідів, їх соціальної адаптації, що потребує удосконалення роботи МСЕК

    Roadmap on Superoscillations

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    Superoscillations are band-limited functions with the counterintuitive property that they can vary arbitrarily faster than their fastest Fourier component, over arbitrarily long intervals. Modern studies originated in quantum theory, but there were anticipations in radar and optics. The mathematical understanding—still being explored—recognises that functions are extremely small where they superoscillate; this has implications for information theory. Applications to optical vortices, sub-wavelength microscopy and related areas of nanoscience are now moving from the theoretical and the demonstrative to the practical. This Roadmap surveys all these areas, providing background, current research, and anticipating future developments

    What drives sound symbolism? Different acoustic cues underlie sound-size and sound-shape mappings

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    Sound symbolism refers to the non-arbitrary mappings that exist between phonetic properties of speech sounds and their meaning. Despite there being an extensive literature on the topic, the acoustic features and psychological mechanisms that give rise to sound symbolism are not, as yet, altogether clear. The present study was designed to investigate whether different sets of acoustic cues predict size and shape symbolism, respectively. In two experiments, participants judged whether a given consonant-vowel speech sound was large or small, round or angular, using a size or shape scale. Visual size judgments were predicted by vowel formant F1 in combination with F2, and by vowel duration. Visual shape judgments were, however, predicted by formants F2 and F3. Size and shape symbolism were thus not induced by a common mechanism, but rather were distinctly affected by acoustic properties of speech sounds. These findings portray sound symbolism as a process that is not based merely on broad categorical contrasts, such as round/unround and front/back vowels. Rather, individuals seem to base their sound-symbolic judgments on specific sets of acoustic cues, extracted from speech sounds, which vary across judgment dimensions

    Studying Adolescent Male Sexuality: Where Are We?

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    This article critically reviews the literature about adolescent males’ sexuality in order to describe the state of the science and to identify promising concepts and research designs that have the potential to guide the next generation of research. A critique was conducted on 94 peer-reviewed studies of sexual behaviors that included a sample of adolescent males; 11 scholarly texts and 2 dissertations. Most studies lacked a theoretical foundation and had cross-sectional designs. For those studies with a theoretical base, 3 perspectives were most often used to guide research: cognitive, biological, or social-environmental. Studies frequently relied on older adolescents or young adult males to report behaviors during early adolescence. Male-only samples were infrequent. Findings include (a) the measurement of sexual activity is frequently limited to coitus and does not explore other forms of “sex”; (b) cognitive factors have been limited to knowledge, attitudes, and intent; (c) little is known about younger males based on their own self-reports; (d) little is known about the normative sexuality development of gay adolescent males; and (e) longitudinal studies did not take into account the complexities of biological, social, and emotional development in interaction with other influences. Research on adolescent sexuality generally is about sexual activity, with little research that includes cognitive competency or young males’ sense of self as a sexual being. The purpose of the paper is to critically review the literature about male sexuality in order to describe the state of the science as well as to identify potential directions to guide the next generation of adolescent male sexual being research.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45299/1/10964_2005_Article_5762.pd

    Determination of the algebraic polynomial of best approximation

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