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91.
We study the efficiency of the incomplete enumeration algorithm for linear and branched polymers. There is a qualitative difference
in the efficiency in these two cases. The average time to generate an independent sample of configuration of polymer with
n monomers varies as n
2 for linear polymers for large n, but as exp(cn
α) for branched (undirected and directed) polymers, where 0<α<1. On the binary tree, our numerical studies for n of order 104 gives α = 0.333±0.005. We argue that α =1/3 exactly in this case.
An erratum to this article can be found at . 相似文献
92.
Complexes of the general formula [ReIII(L)Cl(PPh3)2] have been synthesised by reacting H2L and [ReOCl3(PPh3)2] in ethanol. Here H2L represents imines of α-amino acids (glycine, l-alanine, l-valine, l-phenylalanine) derived from salicylaldehyde and naphthaldehyde. The crystal structure of one complex has been determined. The complexes are mononuclear, paramagnetic and display paramagnetic 1H NMR in CDCl3 solution. Their spectral and redox properties are scrutinised. 相似文献
93.
Susheel K. Verma Girja Shankar Deepak Singh 《International Journal of Infrared and Millimeter Waves》1994,15(3):559-566
A balanced upconverter circuit has been developed in planar transmission line configuration using NEC GaAs beam lead Schottky barrier diodes. RF power output of +1.6 dBm SSB is obtained at Ka-band when up converter is driven by +17 dBm IF and +20 dBm LO signal. 相似文献
94.
Deepak Dhar 《Physics letters. A》1981,81(1):19-22
It is shown that for the two-dimensional planar-rotator model the variance of the number of vortices inside a large loop is proportional to the perimeter of the loop at all temperatures. A similar result holds for the variance of the charge inside a loop in the lattice Coulomb gas model. Hence a topological distinction between the high and low temperature phases of these models (area law versus perimeter law) is not possible. 相似文献
95.
Adarsh Deepak Victor Dulock Billy S. Thomas Harold V. McIntosh 《International journal of quantum chemistry》1969,3(4):445-483
An earlier analysis of the canonical form of a pair of invertible operators obeying the exchange rule is extended to cover a set of operators, between each pair of which a relation of this type exists; and for which a power of each operator is the unit matrix. Such relations define a system which may be regarded as a generalization of the Dirac matrices of relativistic quantum mechanics. We concentrate upon the group theoretic aspects of such a system and its matrix representations. Applications arise from the fact that all projective representations of finite abelian groups take the form of a Dirac Group. In particular, the representations of the magnetic space groups, which are projective representations of the lattice groups, arise in this manner. 相似文献
96.
97.
We study continuum percolation of overlapping circular discs of two sizes. We propose a phenomenological scaling equation
for the increase in the effective size of the larger discs due to the presence of the smaller discs. The critical percolation
threshold as a function of the ratio of sizes of discs, for different values of the relative areal densities of two discs,
can be described in terms of a scaling function of only one variable. The recent accurate Monte Carlo estimates of critical
threshold by Quintanilla and Ziff [Phys. Rev.
E76, 051115 (2007)] are in very good agreement with the proposed scaling relation. 相似文献
98.
This paper presents a multiobjective analog/RF circuit sizing tool using an improved brain storm optimization (IMBSO) algorithm with the purpose of analyzing the tradeoffs between competing performance specifications of analog/RF circuit block. A number of improvements are incorporated into IMBSO algorithm at different steps. At first, the clustering step of IMBSO algorithm is augmented with k-means\(++\) seeding technique to select the initial cluster centroids while clustering using k-means clustering technique. As a second improvement, the proposed IMBSO algorithm makes use of random probabilistic decision-making of river formation dynamics scheme to select optimal cluster centroids during population generation step. As a third improvement, an adaptive mutation operator is incorporated inside the IMBSO algorithm to generate new population. Finally, two separate constraint handling techniques are employed to handle both boundary and functional constraints during analog/RF circuit optimization. The performance of the proposed IMBSO algorithm is demonstrated in finding optimal Pareto fronts among different performance specifications of a two-stage operational amplifier circuit, a folded cascode amplifier circuit and a low noise amplifier circuit. 相似文献
99.
For a finite group G, let m(G) denote the least positive integer such that the union of any m(G) distinct nontrivial conjugacy classes of G together with the identity of G is a subgroup of G. We prove that m(G) = k(G) ?1 for all m(G) ≥2. 相似文献
100.
Single server retrial queueing models in which customers arrive according to a batch Poisson process are considered here. An arriving batch, finding the server busy, enters an orbit. Otherwise, one customer from the arriving batch enters for service immediately while the rest join the orbit. The customers from the orbit (the orbital customers) try to reach the server subsequently with the inter-retrial times exponentially distributed. Additionally, at each service completion epoch, two different search mechanisms, that is, type I and type II search, to bring the orbital customers by the system to service, are switched on. Thus, when the server is idle, a competition takes place among primary customers, customers who come by retrial and by two types of searches. The type I search selects a single customer whereas the type II search considers a batch of customers from the orbit. Depending on the maximum size of the batch being considered for service by a type II search, two cases are addressed here. In the first case, no restriction on batch size is assumed, whereas in the second case, maximum size of the batch is restricted to a pre-assigned value. We call the resulting models as model 1 and model 2 respectively. In all service modes other than type II search, only a single customer is qualified for service. Service times of the four types of customers, namely, primary, repeated, and those who come by two types of searches are arbitrarily distributed (with different distributions which are independent of each other). Steady state analysis is performed and stability conditions are established. A control problem for model 2 is considered and numerical illustrations are provided. 相似文献