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1.
Stere?Ianu?Email author Renzo?Mazzocco Gabriel?Eduard?V?lcu 《Mediterranean Journal of Mathematics》2006,3(3-4):581-592
The main purpose of this paper is to give basic properties of real lightlike hypersurfaces of paraquaternionic manifold and
to prove the nonexistence of real lightlike hypersurfaces in paraquaternionic space forms under some conditions.
Dedicated to the memory of Professor Aldo Cossu 相似文献
2.
Cristina Stere Mihaela‐Corina Iovu Horia Iovu Adrian Boborodea Dan Sorin Vasilescu Simon James Read 《先进技术聚合物》2001,12(5):300-305
The polymerization of ?‐caprolactone initiated by two catalyst systems was studied: (1) carbazole‐potassium in the presence of 18‐crown‐6 ether and (2) NdCl3/TBP/TIBA (neodymiumtrichloride/tri‐n‐butyl‐phosphate/triisobutylaluminium) at the molar ratio 1/3/1. For both initiator systems conversion/time plots were determined and the polymers were characterized by IR, GPC and by 1H‐ and 13C?NMR spectroscopy. Polyesters with the highest molecular weight (M n?44 000 g/mol) were obtained for the polymerizations initiated by the carbazole‐potassium/18‐crown‐6 ether system. The features of the polymerization initiated by the carbazole‐potassium/18‐crown‐6 ether system are discussed on the basis of a simple scheme. The nature of this polymerization is non‐living. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
3.
We study some remarkable classes of metric f-structures on differentiable manifolds (namely, almost Hermitian, almost contact, almost S-structures and K-structures). We state and prove the necessary condition(s) for the existence of maps commuting such structures. The paper contains several new results, of geometric significance, on CR-integrable manifolds and the harmonicity of such maps. 相似文献
4.
P. Budrugeac E. Segal E. Stere Alice Luminita Petre 《Journal of Thermal Analysis and Calorimetry》1996,46(5):1313-1324
The isothermal and non-isothermal degradation of a typical styrenated phthalic acid-maleic acid-propylene glycol polyester were measured. Non-isothermal and isothermal kinetic analyses were performed on the various degradation steps observed. The values of the non-isothermal and the isothermal kinetic parameters are in good agreement. 相似文献
5.
A quasirecurrent pairing of vector fields {X1, X2} (defined in [1]) is investigated on a space-time in two cases: (1)X
1 is spacelike andX
2 is timelike; (2) X1 is null andX
2 space-like. The physical interpretation of these vector fields is given. 相似文献
6.
Stere Ianu? Liviu Ornea Gabriel Eduard V?lcu 《Mediterranean Journal of Mathematics》2012,9(1):105-128
Mixed 3-structures are odd-dimensional analogues of paraquaternionic structures. They appear naturally on lightlike hypersurfaces
of almost paraquaternionic hermitian manifolds. We study invariant and anti-invariant submanifolds in a manifold endowed with
a mixed 3-structure and a compatible (semi-Riemannian) metric. Particular attention is given to two cases of ambient space:
mixed 3-Sasakian and mixed 3-cosymplectic. 相似文献
7.
Mitsuhiro Tsue Osamu Imamura Shunsuke Suzuki Koshiro Fukumoto Shunsuke Nishida George Ianus Yasushige Ujiie Michikata Kono 《Proceedings of the Combustion Institute》2011,33(2):2391-2398
Combustion characteristics of liquid hydrocarbon fuels are studied in a model combustor of SCRAM jet engines. The Mach number and total pressure of main flow in the combustor are 2.0 and 0.38 MPa, respectively, and the total temperature is varied from 1800 to 2400 K. Five kinds of n-alkane fuels such as n-heptane, n-octane, n-decane, n-tridecane and n-hexadecane are employed in experiments. Fuels are injected with a carrier nitrogen gas perpendicular to the mail flow in the combustor and the self-ignition behavior is investigated. The results show that the liquid fuels with lower carbon number have better self-ignition performance. This suggests that physical properties of liquid fuels such as volatility have a dominant effect on the self-ignition. The flame-holding behavior is investigated with the addition of pilot hydrogen to carrier nitrogen gas. The critical equivalence ratio at which the stable combustion keeps after cut-off of the pilot hydrogen is obtained. The relationship between the critical equivalence ratio and carbon number of fuel shows that fuels with the carbon numbers from 8 to 10 have the best flame-holding performance among the tested fuels. These experimental results can be expressed qualitatively by the simplified analysis with the concept of physical and chemical induction times. 相似文献
8.
Stere Ianuş Stefano Marchiafava Gabriel Eduard Vîlcu 《Central European Journal of Mathematics》2010,8(4):735-753
In this paper we introduce paraquaternionic CR-submanifolds of almost paraquaternionic hermitian manifolds and state some basic results on their differential geometry. We also study a class of semi-Riemannian submersions from paraquaternionic CR-submanifolds of paraquaternionic Kähler manifolds. 相似文献
9.
10.
Cristina Stere Mihaela Iovu Adrian Boborodea Dan Sorin Vasilescu Iosif Sorin Fazakas-Anca 《先进技术聚合物》1998,9(6):322-325
The potassium naphthalenide complex with 18-crown-6 is able to initiate anionic polymerization of L -lactide at 20°C. This type of anionic initiator does not have to be removed from the polymer as it does not affect metabolic processes. The ionic polymerization of L -lactide with an initiator based on Zn(II) acetyl acetonate, which is fairly stable, has been investigated. It has been found that this process leads to the corresponding polyesters, at high yields. © 1998 John Wiley & Sons, Ltd. 相似文献