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101.
Wei Li Zhen Yue Artur Lozovoi Oleg Petrov Carlos Mattea Siegfried Stapf 《Journal of Polymer Research》2018,25(11):239
The structure of chain entanglements in the solid state is important for revealing the relationship of structure and properties of polyolefin. In this work, low-field solid-state 1H NMR is used to study the chain dynamics of ultra-high molecular weight polyethylene (UHMWPE) in the solid state. It has been found that the relaxation distribution, analyzed by a multi-exponential inversion program, is an effective method to characterize the heterogeneous chain mobility. It is evidenced from the results that the UHMWPE in a less entangled state presents an obviously heterogeneous distribution of chain mobility in the non-crystalline phase, corresponding to its heterogeneous distribution of entangled points. In comparison, the commercial UHMWPE with a large number of entanglements shows a much more uniform mobility of the non-crystalline components. This heterogeneous distribution of chain mobility becomes even more critical after annealing the samples below the melting point, especially for the less entangled UHMWPE. 相似文献
102.
Robert C. Pullar Yong Zhang Lifeng Chen Shoufeng Yang Julian R.G. Evans Peter Kr. Petrov Andrei N. Salak Dmitry A. Kiselev Andrei L. Kholkin Victor M. Ferreira Neil McN. Alford 《Journal of the European Ceramic Society》2007,27(16):4437-4443
Applying combinatorial methods to materials science offers the opportunity to accelerate the discovery of more efficient dielectric ceramics. High-throughput methods have the potential to investigate the effects of a wide range of dopants on the dielectric properties, and to optimise existing systems, encouraging the short innovation cycles that the communications technology industry requires. The London University Search Instrument (LUSI) is a fully automated, high-throughput combinatorial robot that has the potential capability to produce large numbers of sintered bulk ceramic samples with varying composition in 1 day, as combinatorial libraries on alumina substrates. Ba1−xSrxTiO3 (BST) libraries were produced by LUSI as a proof-of-principle, with x = 0–1 in steps of 0.1, and fired to 1350 and 1400 °C for 1 h. Part I of this paper described the manufacture and physical characterisation of BST libraries, showing a regular change in composition with x across the libraries. In this second part, the dielectric properties of BST libraries produced by LUSI are assessed at frequencies between 100 Hz and 1 MHz, and at temperatures between 150 and 500 K. Local piezoelectric properties were also characterised by scanning probe microscope (SPM). All measurements showed evidence of a clear functional gradient varying with x across the library, with measured r corresponding to expected values for BST. 相似文献
103.
104.
Togobitskaya D. N. Piptyuk V. P. Petrov A. F. Grekov S. V. Mirgorodskaya A. S. 《Metallurgist》2019,62(11-12):1115-1122
Metallurgist - A procedure is developed for calculating criteria for estimation and evaluation of chemical and structural micro-inhomogeneity of ferroalloy production melts. Models are proposed for... 相似文献
105.
P. Petrov 《Zeitschrift für Jagdwissenschaft》1972,18(2):66-76
Zusammenfassung Durch Rundfrage und ergänzende Untersuchungen wurde der gegenwärtige Bestand an Auerwild im südlichen Teil des Verbreitungsgebiets der Art ermittelt. Gegenwärtig leben in Bulgarien etwa 2600 Stück in fünf Vorkommen mit Schwerpunkten in den Rhodopen (70%) und im Rilagebirge (20%). Der zahlenmäßige Rückgang und das Verschwinden an den Rändern der Vorkommensgebiete wird für die letzten 50 Jahre dargestellt. Die Ursache für den Rückgang ist in der zunehmenden Nutzung der Wälder und in der Störung durch die wirtschaftliche Tätigkeit und den Verkehr zu suchen.
Summary By means of questionnaires and supplementary studies, the present conditions of Capercaillie in the southern part of its habitat was ascertained. Currently, about 2,600 birds are living in Bulgaria in five main areas, with concentrations in the Rhodope (70%) and in the Rila Moun-
Résumé Par voie d'enquête complétée par des recherches, l'effectif actuel de l'Urogalle est établi pour la partie méridionale de l'aire d'extension de l'espèce: quelque 2600 têtes d'Urogalle sont réparties en cinq stations, principalement dans les Rhodopes (70%) et dans le Mont Rila (20%). On fait état de la régression de l'espèce en périphérie de son aire de dispersion au cours des cinquante dernières années.Les causes de cette diminution sont à rechercher dans l'exploitation de plus en plus intensive des forêts, dans l'activité économique croissante et dans le développement des voies de communication.相似文献
106.
107.
New designs are proposed for the narrow mold walls in continuous slab-casting machines at OAO MMK, so as to reduce the incidence of defects at the corner of the slabs and enhance the quality of hot-rolled sheet. 相似文献
108.
A. V. Astanin A. D. Dashkevich I. B. Petrov M. N. Petrov S. V. Utyuzhnikov N. I. Khokhlov 《Mathematical Models and Computer Simulations》2017,9(2):133-141
The influence of the Chelyabinsk meteorite’s bow shock wave on the Earth’s surface is modeled. For solving the problem, a 3D statement is considered for its gas-dynamic and seismic parts. The determining equations of a gas-dynamic model and a seismic model are Euler equations with respect to the radiation heat exchange and the equations of linear elasticity theory, respectively. Two parts of the problem are matched by the direct mechanism of the disturbance transmission. A model seismic signal is compared with the real data. Modeling a seismic effect makes it possible to specify the estimate of the typical parameters of the phenomenon (height of the explosion, and the density and characteristic sizes of the meteorite). 相似文献
109.
The application of hardfacing materials for producing high-strength coatings on components working in abrasive wear conditions is one of the important directions of research into increasing the service life of road construction, agricultural and other types of equipment. However, in producing this equipment, the ecological safety requirements are sometimes ignored and this results in negative effects on the environment and the health of personnel. This article describes the results of scientific and research investigations of the team of authors to develop a cladding powder by the method of chemical gas phase deposition of nickel tetracarbonyl on the surface of aluminium oxide particles and application of the powder for producing wear-resistant coatings. The powder materials are deposited in a closed cycle excluding contact of the personnel with toxic substances and emission of contaminants into the atmosphere, resulting in a safe process. Plasma coatings with the required physical–mechanical properties have been produced. This confirms the efficiency of the approaches used in this case and increases the service life of working sections of machines subjected to abrasive wear. 相似文献
110.
E. P. Petrov E. V. Medvedeva 《Journal of Communications Technology and Electronics》2010,55(3):307-315
A method for the synthesis of algorithms for nonlinear filtering of statistically connected (correlated) video sequences of
digital halftone images distorted by a white Gaussian noise is proposed. The method is based on the use of hidden Markov chains
as a mathematical model for video sequences of digital halftone images, which, in limited observation intervals, can be represented
by multidimensional Markov chains. 相似文献