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191.
V. Jha 《Discrete Mathematics》2005,301(1):83-88
A classification is given of all flocks of quadratic cones in , admitting a linear collineation group acting transitively on the conics. The flocks are exactly the Fisher-Thas-Walker, i.e. Betten, or linear. 相似文献
192.
We give a precise expression for the universal weight function of the quantum affine algebra U
q
(
). The calculations use the technique of projecting products of Drinfeld currents on the intersections of Borel subalgebras.
__________
Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 145, No. 1, pp. 3–34, October, 2005. 相似文献
193.
In this paper, we classify all the symmetric quivers and corresponding dimension vectors whose quotient space, classifying the semisimple representation classes, is a complete intersection. The result we obtain is that such quivers can be reduced to a few number of basic quivers, using some elementary types of reduction.
Presented by L. Le BruynMathematics Subject Classification (2000) 16G20. 相似文献
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195.
Vincenzo Di Gennaro 《Transactions of the American Mathematical Society》1997,349(3):1121-1151
Fix integers and let be the set of all integral, projective and nondegenerate varieties of degree and dimension in the projective space , such that, for all , does not lie on any variety of dimension and degree . We say that a variety satisfies a flag condition of type if belongs to . In this paper, under the hypotheses , we determine an upper bound , depending only on , for the number , where denotes the geometric genus of . In case and , the study of an upper bound for the geometric genus has a quite long history and, for , and , it has been introduced by Harris. We exhibit sharp results for particular ranges of our numerical data . For instance, we extend Halphen's theorem for space curves to the case of codimension two and characterize the smooth complete intersections of dimension in as the smooth varieties of maximal geometric genus with respect to appropriate flag condition. This result applies to smooth surfaces in . Next we discuss how far is from and show a sort of lifting theorem which states that, at least in certain cases, the varieties of maximal geometric genus must in fact lie on a flag such as , where denotes a subvariety of of degree and dimension . We also discuss further generalizations of flag conditions, and finally we deduce some bounds for Castelnuovo's regularity of varieties verifying flag conditions.
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199.
Yuanying Li Prof. Wenliang Wang Prof. Dr. Fengyi Liu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(16):4194-4201
The working mechanism including the photoisomerization and thermal isomerization steps of a chiral N-alkyl imine-based motor synthesized by Lehn et al. are revealed by MS-CASPT2//CASSCF and MS-CASPT2//(TD-)DFT methods. For the photoisomerization process of the imine-based motor, it involves both the bright (π,π*) state and the dark (n,π*) state. In addition, the MECI has similar geometry and energy to the minimum of the S1 state, which shows that the process is barrierless and keeps the unidirectionality of rotation well; the result confirms the imine-based motor is a good candidate for a light-driven molecular rotary motor. For the thermal isomerization process of the imine-based motor, there are two even isomerization paths: one with the mechanism of the in-plane N inversion, the energy barriers of which are 29.6 kcal mol−1 at MS3-CASPT2//CAM-B3LYP level and 29.2 kcal mol−1 at MS3-CASPT2//CASSCF level; the other with the mechanism of ring inversion of the cycloheptatriene moiety, with energy barriers of 28.1 kcal mol−1 at MS3-CASPT2//CAM-B3LYP level and 18.1 kcal mol−1 at MS3-CASPT2//CASSCF level. According to the structural feature of the stator moiety, the imine molecule can be used as a two-step or a four-step light-driven rotary motor. 相似文献
200.
Sai Chand 《Entropy (Basel, Switzerland)》2021,23(2)
Predictability is important in decision-making in many fields, including transport. The ill-predictability of time-varying processes poses severe problems for traffic and transport planners. The sources of ill-predictability in traffic phenomena could be due to uncertainty and incompleteness of data and models and/or due to the complexity of the processes itself. Traffic counts at intersections are typically consistent and repetitive on the one hand and yet can be less predictable on the other hand, in which on any given time, unusual circumstances such as crashes and adverse weather can dramatically change the traffic condition. Understanding the various causes of high/low predictability in traffic counts is essential for better predictions and the choice of prediction methods. Here, we utilise the Hurst exponent metric from the fractal theory to quantify fluctuations and evaluate the predictability of intersection approach volumes. Data collected from 37 intersections in Sydney, Australia for one year are used. Further, we develop a random-effects linear regression model to quantify the effect of factors such as the day of the week, special event days, public holidays, rainfall, temperature, bus stops, and parking lanes on the predictability of traffic counts. We find that the theoretical predictability of traffic counts at signalised intersections is upwards of 0.80 (i.e., 80%) for most of the days, and the predictability is strongly associated with the day of the week. Public holidays, special event days, and weekends are better predictable than typical weekdays. Rainfall decreases predictability, and intersections with more parking spaces are highly predictable. 相似文献