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Artificial Immune Systems - Models, algorithms and applications
Copyright © 2010 Academic Research Publishing Agency.This article has been made available through the Brunel Open Access Publishing Fund.Artificial Immune Systems (AIS) are computational paradigms that belong to the computational intelligence family and are inspired by the biological immune system. During the past decade, they have attracted a lot of interest from researchers aiming to develop immune-based models and techniques to solve complex computational or engineering problems. This work presents a survey of existing AIS models and algorithms with a focus on the last five years.This article is available through the Brunel Open Access Publishing Fun
Improving NLO-parton shower matched simulations with higher order matrix elements
In recent times the algorithms for the simulation of hadronic collisions have
been subject to two substantial improvements: the inclusion, within parton
showering, of exact higher order tree level matrix elements (MEPS) and,
separately, next-to-leading order corrections (NLOPS). In this work we examine
the key criteria to be met in merging the two approaches in such a way that the
accuracy of both is preserved, in the framework of the POWHEG approach to
NLOPS. We then ask to what extent these requirements may be fulfilled using
existing simulations, without modifications. The result of this study is a
pragmatic proposal for merging MEPS and NLOPS events to yield much improved
MENLOPS event samples. We apply this method to W boson and top quark pair
production. In both cases results for distributions within the remit of the NLO
calculations exhibit no discernible changes with respect to the pure NLOPS
prediction; conversely, those sensitive to the distribution of multiple hard
jets assume, exactly, the form of the corresponding MEPS results.Comment: 38 pages, 17 figures. v2: added citations and brief discussion of
related works, MENLOPS prescription localized in a subsection. v3: cited 4
more MEPS works in introduction
Adaptive multimodal continuous ant colony optimization
Seeking multiple optima simultaneously, which multimodal optimization aims at, has attracted increasing attention but remains challenging. Taking advantage of ant colony optimization algorithms in preserving high diversity, this paper intends to extend ant colony optimization algorithms to deal with multimodal optimization. First, combined with current niching methods, an adaptive multimodal continuous ant colony optimization algorithm is introduced. In this algorithm, an adaptive parameter adjustment is developed, which takes the difference among niches into consideration. Second, to accelerate convergence, a differential evolution mutation operator is alternatively utilized to build base vectors for ants to construct new solutions. Then, to enhance the exploitation, a local search scheme based on Gaussian distribution is self-adaptively performed around the seeds of niches. Together, the proposed algorithm affords a good balance between exploration and exploitation. Extensive experiments on 20 widely used benchmark multimodal functions are conducted to investigate the influence of each algorithmic component and results are compared with several state-of-the-art multimodal algorithms and winners of competitions on multimodal optimization. These comparisons demonstrate the competitive efficiency and effectiveness of the proposed algorithm, especially in dealing with complex problems with high numbers of local optima
Combining states without scale hierarchies with ordered parton showers
We present a parameter-free scheme to combine fixed-order multi-jet results
with parton-shower evolution. The scheme produces jet cross sections with
leading-order accuracy in the complete phase space of multiple emissions,
resumming large logarithms when appropriate, while not arbitrarily enforcing
ordering on momentum configurations beyond the reach of the parton-shower
evolution equation. This requires the development of a matrix-element
correction scheme for complex phase-spaces including ordering conditions as
well as a systematic scale-setting procedure for unordered phase-space points.
The resulting algorithm does not require a merging-scale parameter. We
implement the new method in the Vincia framework and compare to LHC data.Comment: updated to version published in EPJ
Differential evolution with an evolution path: a DEEP evolutionary algorithm
Utilizing cumulative correlation information already existing in an evolutionary process, this paper proposes a predictive approach to the reproduction mechanism of new individuals for differential evolution (DE) algorithms. DE uses a distributed model (DM) to generate new individuals, which is relatively explorative, whilst evolution strategy (ES) uses a centralized model (CM) to generate offspring, which through adaptation retains a convergence momentum. This paper adopts a key feature in the CM of a covariance matrix adaptation ES, the cumulatively learned evolution path (EP), to formulate a new evolutionary algorithm (EA) framework, termed DEEP, standing for DE with an EP. Without mechanistically combining two CM and DM based algorithms together, the DEEP framework offers advantages of both a DM and a CM and hence substantially enhances performance. Under this architecture, a self-adaptation mechanism can be built inherently in a DEEP algorithm, easing the task of predetermining algorithm control parameters. Two DEEP variants are developed and illustrated in the paper. Experiments on the CEC'13 test suites and two practical problems demonstrate that the DEEP algorithms offer promising results, compared with the original DEs and other relevant state-of-the-art EAs
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