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231.
Alexandr Gre
enko 《Journal of Terramechanics》2007,44(6):451-459
Driving gear of a vehicle (here a track) generates thrust as a reaction to the opposite force taken by the ground. This force causes rearward soil deformation, which is associated with vehicle slippage. The presented compression–sliding (CS) approach, based on field measurements with the original double plate (DP) meter, states that the soil deformation as a consequence to the increasing thrust occurs in two principal stages: (a) primary horizontal soil compression, which steadily increases towards the back of the contact length forming virtual soil segments among neighboring grousers and (b) secondary slide of these sheared off segments referred to as soil blocks, which may collapse under specific conditions. These two stages are separated by a transient situation when both the compression and sliding occur simultaneously.The respective compression–sliding (CS) approach enables to analyze the effect of track arrangement, design and loading on its thrust–slip characteristics. The paper also deals with situation of the existing shear plane theory in view of the CS approach and finally suggests a practical thrust–slip function complying with the CS logic. 相似文献
232.
Alexandr Gre
enko 《Journal of Terramechanics》1995,32(6):325-333
Most existing formulae for computing the tyre footprint area contain the load deflection as a parameter. A user with a tyre catalogue is likely to assess only the nominal area using the catalogue dimensions which are valid for all listed inflation pressure-load combinations. This paper based on a series of measurements suggests the application of a specified correction factor depending on actual tyre load to assess the footprint area of a tyre with an arbitrary loading and inflation pressure using some of the existing formulae and a tyre catalogue. This enables a fair prediction of the mean contact pressure. 相似文献
233.
234.
[1,3]Thiazolo[2′,3′:3,4][1,2,4]triazolo[1,5‐a]pyrimidines – A New Heterocyclic System Accessed via Bromocyclization
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Maksym Fizer Mikhailo Slivka Eduard Rusanov Alexandr Turov Vasil Lendel 《Journal of heterocyclic chemistry》2015,52(3):949-952
A facile access to novel condensed system of [1,3]thiazolo[2′,3′:3,4][1,2,4]triazolo[1,5‐a]pyrimidine is presented. This protocol consists of bromine‐assisted direct electrophilic heterocyclization of 3‐N‐allylamine‐5,6‐dihydro[1,3]thiazolo[2,3‐c][1,2,4]triazole. The bromination took place in acetic acid and gave a good yield of the target product, which was dehydrobrominated by sodium acetate action. 相似文献
235.
Malijevský A 《The Journal of chemical physics》2007,126(13):134710
Density functional theory as proposed by Rosenfeld [Phys. Rev. Lett. 63, 980 (1989)] is used to study hard sphere mixture exposed by cylindrically symmetric external field. Exploiting the symmetry of the system, explicit formulas for the weighted densities are derived. The resulting density profiles are compared with new grand canonical Monte Carlo simulations. The comparison reveals very good agreement between the predicted and simulated results even at high densities and very narrow pores. Finally, simple algorithms for computing complete elliptic functions of the first and second kinds that occur in the derived formulae are presented to make the paper self-contained. 相似文献
236.
An HPLC method has been developed for the separation of anthraquinones with particular attention to the determination of lucidin in commercially available sources of Rubia tinctorum aglycones. Variations of chromatographic conditions have been studied in order to provide suitable resolution of anthraquinones under isocratic conditions on an end‐capped RP C18‐column. 相似文献
237.
Hard elastic samples of linear polyethylene were prepared by melt extrusion at a high velocity of the melt flow and by subsequent annealing of crystallized samples. The deformation behavior of hard elastic samples obtained by annealing of as-spun samples at different temperatures has been analyzed at uniaxial extension resulting in formation of porous structure. Mechanical properties of microporous films in the longitudinal and transverse directions have been investigated. Composite systems consisting of a microporous polyethylene film and a thin layer of an electroconducting polymer have been prepared. Mechanical properties of composite systems, such as elastic modulus, tensile strength, and break elongation, have been compared with the properties of polyethylene substrates. 相似文献
238.
A Markov polling system with infinitely many stations is studied. The topic is the ergodicity of the infinite-dimensional
process of queue lengths. For the infinite-dimensional process, the usual type of ergodicity cannot prevail in general and
we introduce a modified concept of ergodicity, namely, weak ergodicity. It means the convergence of finite-dimensional distributions
of the process. We give necessary and sufficient conditions for weak ergodicity. Also, the “usual” ergodicity of the system
is studied, as well as convergence of functionals which are continuous in some norm.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
239.
Evgenij V. Zarudnitskii Vladimir V. Ivanov Alexandr A. Yurchenko Alexandr M. Pinchuk Andrej A. Tolmachev 《Heteroatom Chemistry》2002,13(2):146-152
Phosphorylation of 4‐ and 1‐substituted 1,2,4‐triazoles with PCl3, PhPCl2, Ph2PCl, and (Et2N)2 PCl was carried out. A novel phosphorus‐containing condensed heterocyclic system ( 18, 23 ) was constructed by the reactions of 2‐(1H‐1,2,4‐triazol‐1‐yl)‐1‐(4‐chlorophenylcarboxamido)‐5‐trifluoromethylbenzene with PBr3 and PhPBr2. Treatment of the bromophosphonite 18 with an excess of morpholine in the presence of sulfur resulted in a diazaphosphinine ring opening and provided functionalized 1H‐1,2,4‐triazol‐5‐ylphosphonic acid derivatives 21 and 22 . © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:146–152, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/hc.10010 相似文献
240.
Konstantin N. Gavrilov Alexei A. Shiryaev Sergey V. Zheglov Vladislav K. Gavrilov Nikolay N. Groshkin Marina G. Maksimova Alexandr N. Volov Ilya A. Zamilatskov 《Tetrahedron》2014
A small family of P,P∗-bidentate C1-symmetric ligands containing 1,3,2-diazaphospholidine rings with stereogenic phosphorus atoms has been prepared. Palladium catalytic systems with these phosphine-diamidophosphites afforded 95% and 63% ees in asymmetric allylic substitution and desymmetrization processes, respectively. The influence of the nature of both the phosphine and diamidophosphite moieties of these compounds on the enantioselectivity is discussed. The ‘mixed-ligand approach’ in Pd-catalyzed asymmetric allylation with participation of some new P∗-monodentate diamidophosphites and PPh3 is also considered. 相似文献