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1.
O. S. Chizhov B. A. Dmitriev B. M. Zolotarev A. Ya. Chernyak N. K. Kochetov 《Journal of mass spectrometry : JMS》1969,2(10):947-952
The trifluoroacetyl derivatives of alditols are convenient compounds for mass spectrometric investigation as they are easily obtainable and highly volatile. They show simple fragmentation patterns with intensive peaks in the high mass range. Trifluoroacetates of alditols may be used for detection and location of deoxy groups in the molecule. 相似文献
2.
3.
The t–J model is analysed in the limit of strong anisotropy, where the transverse components of electron spin are neglected. We propose a slave-particle-type approach that is valid, in contradiction to many of the standard approaches, in the low-doping regime and becomes exact for a half-filled system. We describe an effective method that allows to numerically study the system with the no-double-occupancy constraint rigorously taken into account at each lattice site. Then, we use this approach to demonstrate the destruction of the antiferromagnetic order by increasing the doping and formation of Nagaoka polarons in the strong interaction regime. 相似文献
4.
A. E. Kochetov A. S. Mikhaylushkin 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,61(4):441-444
We report the results of our first-principles studies
of the interaction between an infinite monoatomic gold nanowire and
a carbon-monoxide molecule. We show that the gold
monoatomic nanowire is capable of absorbing the CO molecule at the
distances of about 1.8 ? and forms a bond with the carbon atom.
Further, we find that dissociation of the
CO molecule as the source of gold nanowire contamination with carbon, which is
widely discussed in literature as the possible reason for
the striking stability of gold nanowires under stretching, is thermodynamically
unfavored. 相似文献
5.
N. A. Kochetov B. S. Seplyarskii 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2018,92(1):47-52
The effect the duration of the mechanical activation (MA) of preliminarily granulated mixtures of 5Ti + 3Si with titanium powder of different grades has on the dependences of combustion rates and changes in the length of samples after synthesis is studied. The dependences of the average particle size of a mixture on the duration of activation are established. It is shown that initial mixtures containing titanium of different grades have different combustion rates. It is concluded that mechanical activation leads to equalization of the combustion rates for powder mixtures at MA durations of more than 7 min and for preliminarily granulated mixtures at MA durations of 3 min. For powder mixtures, the combustion rate changes nonmonotonically as the duration of MA grows. For preliminarily granulated mixtures, it first slows and then increases monotonically. An explanation of the observed dependences is proposed. It is shown that in contrast to powder mixtures, there is a sudden increase in the relative length of samples during combustion after the MA of granulated mixtures with a duration of 1 min. This is because with granular MA mixtures, the main evolution of gas from the decomposition of bonds occurs behind the combustion front, in contrast to mixtures without MA. It is shown that the dependences of the relative length of the samples after burning on the duration of MA are close to those of mixtures with both grades of titanium. 相似文献
6.
O. I. Kochetov 《Physics of Atomic Nuclei》2004,67(11):1995-2001
7.
Ekaterina Alekseeva Yuri Kochetov Alexander Plyasunov 《European Journal of Operational Research》2008
We study the complexity of finding local minima for the p-median problem. The relationship between Swap local optima, 0–1 local saddle points, and classical Karush–Kuhn–Tucker conditions is presented. It is shown that the local search problems with some neighborhoods are tight PLS-complete. Moreover, the standard local descent algorithm takes exponential number of iterations in the worst case regardless of the tie-breaking and pivoting rules used. To illustrate this property, we present a family of instances where some local minima may be hard to find. Computational results with different pivoting rules for random and Euclidean test instances are discussed. These empirical results show that the standard local descent algorithm is polynomial in average for some pivoting rules. 相似文献
8.
V. L. Bychkov S. A. Volkov I. V. Kochetov 《Russian Journal of Physical Chemistry B, Focus on Physics》2011,5(6):940-945
This paper analyzes the local processes of ionization and electron loss in the early stages of an electric discharge in humid
air at altitudes of 0–12 km. The processes of ionization in an external electric field, background ionization, attachment
and detachment of electrons from atomic and molecular oxygen, charge transfer, and the conversion of negative ions are considered.
The dependences of the rate constants on the pressure are taken into account. It is shown that the electric field strength
at which the effective ionization of air begins decreases with increasing altitude. 相似文献
9.
In the (r∣p)-centroid problem, two players, called leader and follower, open facilities to service clients. We assume that clients are identified with their location on the Euclidean plane, and facilities can be opened anywhere in the plane. The leader opens p facilities. Later on, the follower opens r facilities. Each client patronizes the closest facility. In case of ties, the leader’s facility is preferred. The goal is to find p facilities for the leader to maximize his market share. We show that this Stackelberg game is \(\varSigma_{2}^{P}\) -hard. Moreover, we strengthen the previous results for the discrete case and networks. We show that the game is \(\varSigma_{2}^{P}\) -hard even for planar graphs for which the weights of the edges are Euclidean distances between vertices. 相似文献
10.