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991.
In this paper, the growth and Gelfand-Kirillov dimension of some primitive abundant semigroups are investigated. It is shown that for certain primitive abundant (regular) semigroup S, S as well as the semigroup algebra K [S] has polynomial growth if and only if all of its cancellative submonoids (subgroups) T as well as K[T] have polynomial growth. As applications, it is shown that if S is a finitely generated primitive inverse monoid having the permutational property, then clK dim K[S] = GK dim K[S] = rk(S). 相似文献
992.
We study the efect of"ghost forces"for a quasicontinuum method in three dimension with a planar interface."Ghost forces"are the inconsistency of the quasicontinuum method across the interface between the atomistic region and the continuum region.Numerical results suggest that"ghost forces"may lead to a negilible error on the solution,while lead to a fnite size error on the gradient of the solution.The error has a layer-like profle,and the interfacial layer width is of O(ε).The error in certain component of the displacement gradient decays algebraically from O(1)to O(ε)away from the interface.A surrogate model is proposed and analyzed,which suggests the same scenario for the efect of"ghost forces".Our analysis is based on the explicit solution of the surrogate model. 相似文献
993.
For arbitrary c00, if A is a subset of the primes less than x with cardinality δx(logx)-1, δ≥(logx)-c0, then there exists a positive constant c such that the cardinality of A+A is larger than cδx(loglogx)-1. 相似文献
994.
称环R是右线性McCoy的,如果R[x]中非零线性多项式f(x),g(x)满足I(x)g(x)=0,则存在非零元素r∈R使得f(x)r=0.设a是环R的自同态,通过用斜多项式环R[x;a]中的元素代替一般多项式环R[x]中的元素而引入a-线性McCoy环的概念.讨论了a-线性McCoy环的基本性质和扩张性质. 相似文献
995.
P. Wang Zi Wu G.Q. Chen B.S. Cui 《Communications in Nonlinear Science & Numerical Simulation》2013,18(12):3382-3406
To further address the characteristic of contaminant transport in wetlands of a multi-layer structure, environmental dispersion of a pulsed contaminant emission into a steady flow is analytically explored in this paper for the typical case of a respectively vegetated or packed three-layer wetland dominated with free-water-surface-effect. The hierarchical structure for the critical length and duration of the contaminant cloud is illustrated for the dispersion of typical contaminant constituents. 相似文献
996.
997.
Anilido-imine ligands o-C6H4(NHAr1)(CH=NAr2), in which Ar1 is 2,6-diisopropylbenzyl group and Ar2 contains fluorine (HL1) or methoxyl (HL2) group on ortho-position of phenyl substituent, were synthesized for constructing rare-earth metals based complexes of 1a–1c (HL1 based Sc, Lu, Y) and 2a–2c (HL2 based Sc, Lu, Y). Based on their NMR spectra and X-ray single-crystal structures, the side-arm group of -F and -OMe is identified to chelate to the corresponding central metal. The twisted angles between two planes formed by chelated heteroatoms (N, N, F for HL1 and N, N, O for HL2) are observed, in which the largest dihedral angle (53.3°) for HL1-Y and the smallest dihedral angle (44.32°) for HL2-Sc are detected. After being activated by AliBu3 and [Ph3C][B(C6F5)4], these catalysts showed great activity for isoprene polymerization. Bearing the same ligand HL1, smaller scandium based complex 1a and middle size of lutetium based 1b provided lower cis-1,4-selectivity (57.3% and 64.2%), larger yttrium complex 1c displayed high cis-1,4-selectivity (84%). Chelating by crowded HL2, small size of scandium complex 2a provided impressive trans-1,4-selectivity (93.0%), middle lutetium based 2b displayed non-selectivity and larger yttrium complex 2c showed clear cis-1,4-selectivity (83.3%). Moreover, 2a/AliBu3 system showed the quasi-living chain transfer capability. 相似文献
998.
Jianming Cui Wenxiu Kong Xiaojun Zhang Da Chen Qingtian Zeng 《Entropy (Basel, Switzerland)》2021,23(7)
Polar code has been adopted as the control channel coding scheme for the fifth generation (5G), and the performance of short polar codes is receiving intensive attention. The successive cancellation flipping (SC flipping) algorithm suffers a significant performance loss in short block lengths. To address this issue, we propose a double long short-term memory (DLSTM) neural network to locate the first error bit. To enhance the prediction accuracy of the DLSTM network, all frozen bits are clipped in the output layer. Then, Gaussian approximation is applied to measure the channel reliability and rank the flipping set to choose the least reliable position for multi-bit flipping. To be robust under different codewords, padding and masking strategies aid the network architecture to be compatible with multiple block lengths. Numerical results indicate that the error-correction performance of the proposed algorithm is competitive with that of the CA-SCL algorithm. It has better performance than the machine learning-based multi-bit flipping SC (ML-MSCF) decoder and the dynamic SC flipping (DSCF) decoder for short polar codes. 相似文献
999.
1000.
Effects of effective attractive multi-body interaction on quantum phase and transport dynamics of a strongly correlated bosonic gas across the superfluid to Mott insulator transition 下载免费PDF全文
We theoretically investigate quantum phases and transport dynamics of ultracold atoms trapped in an optical lattice in the presence of effective multi-body interaction.When a harmonic external potential is added,several interesting phenomena are revealed,such as the broadening and the emergence of a central insulator plateau and the phase transition between superfluid and Mott insulator phase.We also study the transport of the system which runs across the superfluid–insulator transition after ramping up the lattice,and predict a slower relaxation which is attributed to the influence of the multi-body interaction on the mass transport. 相似文献