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排序方式: 共有419条查询结果,搜索用时 31 毫秒
411.
We perform large-eddy simulations of turbulent MHD channel flow with a streamwise magnetic field using a pseudo spectral method. The streamwise magnetic field leads to turbulent drag reduction due to the selective Joule damping of certain flow structures. Near the walls, the turbulent mean velocity profile retains the logarithmic layer but the von Karman constant decreases with increasing magnetic field strength. In the outer region, the flow is characterized by persistent streaky structures of large streamwise extent, which lead to a rather flat mean velocity profile. In addition, the streamwise velocity fluctuations develop a pronounced second peak upon increasing the magnetic induction as well as a second logarithmic layer that increases in steepness. We find that Prandtl's classical mixing-length model with a variable Kármán constant can describe the modified logarithmic layer reasonably accurately in a wide range of Reynolds and Hartmann numbers. However, the flow modification near the center of the channel is not properly captured by this approach. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
412.
Galina L. Levit Dmitry A. GruzdevVictor P. Krasnov Evgeny N. ChulakovLiliya Sh. Sadretdinova Marina A. EzhikovaMikhail I. Kodess Valery N. Charushin 《Tetrahedron: Asymmetry》2011,22(2):185-189
The acylative kinetic resolution of racemic 2-methyl-1,2,3,4-tetrahydroquinoline and 2,3-dihydro-3-methyl-4H-1,4-benzoxazine using acyl chlorides of N-phthaloyl-(S)-phenylalanine, N-phthaloyl-3-(4-nitrophenyl)-(S)-alanine and N-phthaloyl-O-methyl-(S)-tyrosine as chiral resolving agents has been carried out. It is shown that the effectiveness of an acylative kinetic resolution depends on the electronic effects of substituents in the phenyl fragment of the acylating agent and increases as the electron-donating properties of the para-substituent (OMe > H > NO2) in phenyl fragment of N-phthaloyl-3-aryl-(S)-alanyl chlorides increase; conducting the process at a reduced temperature also contributes to an enhancement of the kinetic resolution. 相似文献
413.
M. V. Serzhantova A. A. Kuzubov A. S. Fedorov P. O. Krasnov F. N. Tomilin 《Journal of Experimental and Theoretical Physics》2011,112(4):664-667
The influence of boron and nitrogen vacancies and divacancies on the electronic structure of a hexagonal boron nitride h-BN monolayer is studied. In the presence of vacancies in the structure, the introduced states appear in the forbidden band.
The position of an introduced state with respect to the upper occupied level and the lower vacant level depends on deformation.
Calculations show that, depending on the defect type and the magnitude of the applied deformation, the introduced state can
be both localized and not localized on atoms surrounding the defect. When the state is localized in the system, the inhomogeneous
distribution of the spin density is observed, resulting in the appearance of the magnetic moment in the system. 相似文献
414.
S. M. Piyadin T. A. Vasiliev Yu. V. Gurchin A. Yu. Isupov Yu. T. Karachuk V. A. Krasnov A. K. Kurilkin P. K. Kurilkin V. P. Ladygin A. N. Livanov G. Martinska S. G. Reznikov A. K. Semenov A. E. Tumanov A. N. Khrenov M. Janek 《Physics of Particles and Nuclei Letters》2011,8(2):107-113
A design for a ΔE-E detector to investigate deuteron breakup in the Nuclotron-M internal target in a deuteron energy interval of 300–500 MeV is presented. The high-voltage power supply system of the PMT-63, which is based on the computer-controlled Wenzel Electronik module, is briefly described. A light-emitting diode (LED) monitoring system for the ΔE-E detector is considered. The results of testing the ΔE-E detector using cosmic muons and deuteron beams of the Nuclotron are presented. 相似文献
415.
P. K. Kurilkin V. P. Ladygin T. Uesaka K. Suda Yu. V. Gurchin A. Yu. Isupov K. Itoh M. Janek J. -T. Karachuk T. Kawabata A. N. Khrenov A. S. Kiselev V. A. Kizka V. A. Krasnov N. B. Ladygina A. N. Livanov Y. Maeda A. I. Malakhov S. G. Reznikov S. Sakaguchi H. Sakai Y. Sasamoto K. Sekiguchi M. A. Shikhalev T. A. Vasiliev 《Physics of Particles and Nuclei Letters》2011,8(10):1081-1083
New polarimeter based on the asymmetry measurement in dp-elastic scattering has been constructed at internal target at Nuclotron (JINR). The result on the deuteron analyzing powers A y , A yy and A xx in the deuteron-proton (dp) elastic scattering at the energies of 880 and 2000 MeV are presented. They are compared with different theoretical approaches. 相似文献
416.
S. M. Piyadin Yu. V. Gurchin A. A. Terehin A. Yu. Isupov M. Janek J. -T. Karachuk A. N. Khrenov V. A. Krasnov A. K. Kurilkin P. K. Kurilkin V. P. Ladygin A. N. Livanov G. Martinska V. P. Rapatsky S. G. Reznikov A. K. Semenov A. E. Tumanov T. A. Vasiliev 《Physics of Particles and Nuclei Letters》2011,8(10):1084-1086
The experimental program on the study of deuteron-proton interaction at Internal Target at Nuclotron is discussed. Recent results obtained for dp-elastic scattering and dp-breakup reactions at intermediate energies are presented. The status of the DSS setup upgrade is reported. 相似文献
417.
Victor P. Krasnov Vera V. Musiyak Galina L. Levit Dmitry A. Gruzdev Valeriya L. Andronova Georgii A. Galegov Iana R. Orshanskaya Ekaterina O. Sinegubova Vladimir V. Zarubaev Valery N. Charushin 《Molecules (Basel, Switzerland)》2022,27(13)
A series of pyrimidine conjugates containing a fragment of racemic 7,8-difluoro-3,4-dihydro-3-methyl-2H-[1,4]benzoxazine and its (S)-enantiomer attached via a 6-aminohexanoyl fragment were synthesized by the reaction of nucleophilic substitution of chlorine in various chloropyrimidines. The structures of the synthesized compounds were confirmed by 1H, 19F, and 13C NMR spectral data. Enantiomeric purity of optically active derivatives was confirmed by chiral HPLC. Antiviral evaluation of the synthesized compounds has shown that the replacement of purine with a pyrimidine fragment leads to a decrease in the anti-herpesvirus activity compared to the lead compound, purine conjugate. The studied compounds did not exhibit significant activity against influenza A (H1N1) virus. 相似文献
418.
419.