Explore the vast range of titles available.

The 1 MW experimental stand was modernized with a scroll swirler and a crushed fuel supply system. Comparative data on combustion and gasification of coal fuel crushed in high-stress mills - disintegrator, vibrocentrifugal and hammer mill - at a stand with a thermal power of 1 MW were obtained. The experiments used coal of the Kuznetsk Basin, grade D, with technical characteristics: W r , % = 5.4; A r , %=22.3; V r , % = 32.3; Q sr , MJ/kg = 20.0. Elemental analysis showed that: C r , %=54.6; H r , % = 4.1; N r , % = 1.3; S r , % = 0.5; O r = 11.8. In experiments with grinding coal on a disintegrator mill, the value of H 2 = 4.5 vol.% and CO = 9.4 vol.%, when grinding in a vibro-centrifugal mill, the values of H 2 = 0.6 vol.% and CO = 5.8 vol.%, when grinding in a hammer mill, the values of H 2 = 0.3 vol.% and CO = 2.8 vol.%. When studying the combustion of mechanochemically treated coal samples, it was found that, all other things being equal, the gasification parameters, namely, the gas concentration and the distribution of temperature zones, depend strongly on the type of equipment used for processing. In particular, processing to approximately the same degree of fineness in mechanical mills-activators with constrained impact and in free impact mills (disintegrators) resulted in different flame parameters.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

The system of factors affecting the spatial distribution of the retail trade and service establishments has changed dramatically since socialist times. The administrative regulation lost its almost complete dominance and turned into one of the market forces. In contrast, the impact of the urban environment under very free market conditions substantially increased. We show the main directions of this influence. Two generalized indicators that we use describe macro trends in the development of the spatial system of retail trade and services. One of them, which we call the urban morphology, is of a concentric effect, another - transportation pattern - adds the sectoral component to the retail trade and services geography. Five systems of spatial attractions differently affect the distribution of different branches.

Method for determining parameters of the burning rate law including combustion of high energy material samples in a manometric bomb is proposed. This method is based on solving the inverse problem of internal ballistics in an integral formulation. Unlike the prior versions embodiments of the experimental setup, the principle of ignition of a HEM sample by a heated spiral is used herein. In the prior versions, the ignition of the sample was carried out with black powder, which introduced errors due to gas formation during the burning of the powder. In addition, heat-insulated inserts are installed on inner walls of manometric bomb to prevent heat losses. The results of the method verification for model high energy material are discussed. Verification of the proposed method for identifying the parameters of the burning rate law was carried out for the model HEM composition with known values of thermophysical and ballistic characteristics. The integral method allows determining parameters of the burning rate law u1, v with the error of not more than 3-4% by experimental dependence p(t) measured with a random error of 10%. At the same time errors of determination u1, v by the differential method is 14-32%.

The accumulation of residual stresses during the manufacturing of a carbon-epoxy composite induces defects such as interlayer delamination and the formation of microcracks in the matrix. In the present study, the effect of the polymerization process in the thermoset matrix of the laminated composite plate on the stress state near the free edge is investigated. To estimate the residual stresses in the laminate, the simulation of the curing process was accomplished using coupled thermal and structural analysis. The proposed approach was implemented in ABAQUS software via a special user subroutine, and the validation problem of plate distortion after the curing is presented. The modeling of the cut process was performed, which corresponds to the plate machining, for the analysis of the residual stress re-distribution after the cut with formation of a free edge. In addition, the manufacturing process of the laminate with the initial crack was simulated for the analysis of crack growth caused by residual stresses. Finally, the modeling of uniaxial load to the laminate up to failure with the presence of residual stresses and consideration of a crack in the vicinity of the free edge is presented.

Scheelite (CaWO 4 ) is a major ore mineral of the Vostok-2 skarn deposit, which is located in Primorsky krai and confined to the Central Sikhote-Alin fault. Two dominant ore types are recognized on the basis of mineral composition and geochemical characteristics: skarn and vein quartz. The work presents the results of a comprehensive study (mineragraphy, cathodoluminescence, X-ray microanalysis, and laser ablation inductively couple plasma mass spectrometry) of scheelite. Its internal structure, cathodoluminescence, UF radiation, trace element content, Eu/Eu* ratio, and a rare-earth element (REE) pattern are the key indicators of mineral formation. These features allowed us to reveal various REE incorporations in structure of scheelite from skarn ores and quartz veins: 3Ca 2+ ↔ 2REE 3+ + and Ca 2+ + W 6+ ↔ REE 3+ + Nb 5+ , respectively (where is the vacancy in the Ca site). Three scheelite types are distinguished from specific REE pattern and their temporal relations are established. Because scheelite inherits the REEs from a mineral-forming medium, we showed the process of the evolution of ore-forming fluid, the pulsating character of the contribution of the matter, and its common source. The reducing mineral formation conditions are proven for the deposit in general.

The mechanical behavior of titanium alloys has been mostly studied in quasi-static conditions when the strain rate does not exceed 10 s−1, while the studies performed in dynamic settings specifically for Ti-based composites are limited. Such data are critical to prevent the “strength margin” approach, which is used to assure the part performance under dynamic conditions in the absence of relevant data. The purpose of this study was to obtain data on the mechanical behavior of Ti-based composites under dynamic condition. The Metal Matrix Composites (MMC) on the base of the alloy Ti-6Al-4V (wt.%) were made using Blended Elemental Powder Metallurgy with different amounts of reinforcing particles: 5, 10, and 20% of TiC or 5, 10% (vol.) of TiB. Composites were studied at high strain rate compression ~1–3 × 103·s−1 using the split Hopkinson pressure bar. Mechanical behavior was analyzed considering strain rate, phase composition, microstructure, and strain energy (SE). It is shown that for the strain rates up to 1920 s−1, the strength and SE of MMC with 5% TiC are substantially higher compared to particles free alloy. The particles TiC localize the plastic deformation at the micro level, and fracturing occurs mainly by crushing particles and their aggregates. TiB MMCs have a finer grain structure and different mechanical behavior. MMC with 5 and 10% TiB do not break down at strain rates up to almost 3000 s−1; and 10% MMC surpasses other materials in the SE at strain rates exceeding 2200 s−1. The deformation mechanism of MMCs was evaluated.

Background Poor psychological well-being is both prevalent among South Africans living with HIV and has been associated with poor HIV clinical outcomes. However, the relationship between disclosure and psychological well-being remains unclear. This analysis sought to examine the relationship between two disclosure-related variables, disclosure status and reaction received, and psychosocial well-being among a sample of young adults living with HIV (YALWH) in urban South Africa. Method This was a secondary analysis using observational data from Standing Tall, a randomized controlled trial that recruited 100 participants ages 18–24 who tested positive for HIV after initially presenting to two well-established mobile clinics for HIV testing. Interviews investigating primary and secondary outcomes of interest were done at baseline and 6 months following recruitment. Results About half (51%) of participants disclosed their HIV status within 6 months after recruitment. Simple linear regression analyses revealed that disclosure of HIV status within 6 months after study enrollment predicted significantly lower levels of disclosure concerns and internalized stigma ( p  < 0.05). Reactions to disclosure were not significantly associated with any of the measures of psychosocial well-being considered in this analysis ( p  > 0.05). Conclusion The results suggest that the act of disclosure among newly diagnosed YALWH may be associated with reductions in internalized stigma. In addition, the finding that the act of disclosure may be a more important determinant of psychosocial well-being than the reaction to disclosure has important implications for interventions designed to promote disclosure and psychosocial well-being in YALWH.

The work was financially supported by: (a) the Academy of Finland grant 250444; (b) a Spanish Ramon y Cajal grant RYC-2014-16263 and Kone Foundation grant 44–6977 (MD); (c) University of Helsinki LUOVA Doctoral Program (GT); and (d) the Excellence Project CGL2017–82782-P (VP) financed by the Spanish Ministry of Economy, Industry and Competitiveness (MINECO), the Agencia Estatal de Investigación (AEI) and the Fondo Europeo de Desarrollo Regional (FEDER, EU)