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Liu J.,Hunan Institute of Technology
International Journal of Modeling, Simulation, and Scientific Computing | Year: 2017

Online sequential extreme learning machine (OS-ELM) for single-hidden layer feedforward networks (SLFNs) is an effective machine learning algorithm. But OS-ELM has some underlying weaknesses of neglecting time series timeliness and being incapable to provide quantitative uncertainty for prediction. To overcome these shortcomings, a time series prediction method is presented based on the combination of OS-ELM with adaptive forgetting factor (AFF-OS-ELM) and bootstrap (B-AFF-OS-ELM). Firstly, adaptive forgetting factor is added into OS-ELM for adjusting the effective window length of training data during OS-ELM sequential learning phase. Secondly, the current bootstrap is developed to fit time series prediction online. Then associated with improved bootstrap, the proposed method can compute prediction interval as uncertainty information, meanwhile the improved bootstrap enhances prediction accuracy and stability of AFF-OS-ELM. Performances of B-AFF-OS-ELM are benchmarked with other traditional and improved OS-ELM on simulation and practical time series data. Results indicate the significant performances achieved by B-AFF-OS-ELM. © 2017 World Scientific Publishing Company

Xiao K.,Hunan Institute of Technology | He X.-K.,Hunan First Normal University | Zhu J.-Y.,Beijing Normal University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2013

Phenomenological effect of the super-inflation in loop quantum cosmology (LQC) is discussed. We investigate the case that the Universe is filled with the interacting field between massive scalar field and radiation. Considering the damping coefficient Γ as a constant, the changes of the scale factor during super-inflation with four different initial conditions are discussed, and we find that the changes of the scale factor depends on the initial values of energy density of the scalar field and radiation at the bounce point. But no matter which initial condition is chosen, the radiation always dominated at the late time. Moreover, we investigate whether the super-inflation can provide enough e-folding number. For the super-inflation starts from the quantum bounce point, the initial value of Hubble parameter H(ti)~0, then it is possible to solve the flatness problem and horizon problem. As an example, following the method of [18] to calculate particle horizon on the condition that the radiation dominated at bounce point, and we find that the Universe has had enough time to be homogeneous and isotopic. © 2013 Elsevier B.V.

Guo Y.,Hunan Institute of Technology
International Journal of Innovative Computing, Information and Control | Year: 2016

This paper deals with a stochastic two-species competitive model of plankton alleopathy. Some very verifiable criteria on the uniformly weakly persistent in the mean almost surely (a.s.) and extinction for each species are obtained. Moreover, we also prove that there is a stationary distribution to this system and it has the ergodic property. Finally, some sufficient conditions for global asymptotic stability of the positive solution are established. An example is given to illustrate our main theoretical findings. Our results are new and complement previously known results. © 2016, ICICI International .

Zhang Q.,Guizhou University of Finance and Economics | Yang L.,Hunan City University | Liao D.,Hunan Institute of Technology
Information Sciences | Year: 2014

This paper deals with the existence, the boundedness and the asymptotic behavior of the positive solutions to a first order fuzzy Ricatti difference equation xn+1=A+xnB+xn,n=0,1,...where { xn} is a sequence of positive fuzzy numbers, A,B and the initial value x0 are positive fuzzy numbers. Moreover an example is given to demonstrate the effectiveness of the results obtained.

Xu R.,Hunan Institute of Technology
ICIC Express Letters | Year: 2016

In this paper, a single species logarithmic population model is investigated. By applying the contraction mapping principle, a set of sufficient conditions is obtained for the existence and uniqueness of almost periodic solution of the single species logarithmic population model. The obtained sufficient conditions are given in terms of the algebraic inequalities which are easily checked. The results of this paper are completely new and generalize those of the previous studies. © 2016 ICIC International.

Li L.,Hunan Institute of Technology
Journal of Alloys and Compounds | Year: 2013

Microstructure and texture evolution during super plastic deformation of Mg-Gd-Y-Zr extruded rods were investigated in the study. For the purposes, the tensile tests under super plastic deformation condition were conducted at different strain levels. The static annealing tests were performed to reveal the micro structural evolution only influenced by thermal load. Grain structure analysis proves that initial grain refinement during the preheating stage is driven by store energy inherited from extrusion deformation. Microstructure and texture analysis suggests that deformation mechanisms are initial grain boundary sliding and subsequent slip creep. Moreover, the β phases (Mg5 (Gd, Y)) on (sub) grain boundaries hinder grain boundary sliding and continuous dynamic recrystallization. Macro-texture evolution shows that texture components varied according to the transition of deformation mechanisms. Micro-texture measurement using EBSD proves that β phase has undergone severe deformation before elongation-to-failure. © 2012 Elsevier B.V. All rights reserved.

Li L.,Hunan Institute of Technology
Materials Science and Engineering A | Year: 2011

Microstructural evolution and texture of a cast Mg-9Gd-4Y-0.6Zr ingot under hot compression were studied in this paper. Post-deforming microstructures were characterized by optical microscopy, scanning electron microscopy and transmission electron microscopy, while crystallographic orientation information was obtained from X-Ray macro-texture measurement and EBSD micro-texture analysis. Dynamic recrystallization (DRX) initiated from the deformation bands (DB) forming on original grain boundaries; the DB became widen with continuously conversion of low-angle-boundary grains into high-angle-boundary grains. The tendency of strain localization increased with Z parameter. The macro-texture analysis indicates that uniaxial compression yielded out the randomized basal texture component. This texture component was found to be strengthened with increasing Z parameter. The micro-texture analysis shows that the deviation from the ideal basal texture arose from orientated growth within DBs. Moreover, the localization deformation promoted dynamic precipitation within DBs, which inhibited the development of DRX. © 2011 Elsevier B.V.

Liu K.,Hunan Institute of Technology
Gaodeng Xuexiao Huaxue Xuebao/Chemical Journal of Chinese Universities | Year: 2014

α-Halomethylketones are building blocks for the synthesis of various compounds due to their selective transformations with different reagents. Moreover, a wide range of α-halomethylketone derivatives attract increasing interests in pharmaceutical chemistry. α-Halomethylketones are also widespread used as intermediates in organic synthesis, such as in Favorskii rearrangement and Reformatsky reaction. However, their direct synthesis from the corresponding methylktones by N-halosuccinimides, molecular halogen and metal halides has been plagued by poor regioselectivity and over-halogenation. For the above reasons, a simple, convenient and environmentally benign protocol to synthesize the α-halomethylketones was developed by catalytic hydration of haloalkynes, which can be easily prepared in one step from commercial terminal alkynes. In the presence of 3%(molar fraction) BrettPhosAuNTf2 and 3 mmol H2O in dichloroethane at room temperature, a broad range of haloalkynes were converted into α-halomethylketones in excellent yield through gold-catalyzed hydration reaction. The presented methodology will provide new strategies for α-halomethylketones-type drug design and synthesis, which has important academic significance and application value.

Kuang F.,Nanjing University of Science and Technology | Kuang F.,Hunan Institute of Technology | Xu W.,Nanjing University of Science and Technology | Xu W.,Changsha University of Science and Technology | Zhang S.,Hunan Institute of Technology
Applied Soft Computing Journal | Year: 2014

A novel support vector machine (SVM) model combining kernel principal component analysis (KPCA) with genetic algorithm (GA) is proposed for intrusion detection. In the proposed model, a multi-layer SVM classifier is adopted to estimate whether the action is an attack, KPCA is used as a preprocessor of SVM to reduce the dimension of feature vectors and shorten training time. In order to reduce the noise caused by feature differences and improve the performance of SVM, an improved kernel function (N-RBF) is proposed by embedding the mean value and the mean square difference values of feature attributes in RBF kernel function. GA is employed to optimize the punishment factor C, kernel parameters σ and the tube size É of SVM. By comparison with other detection algorithms, the experimental results show that the proposed model performs higher predictive accuracy, faster convergence speed and better generalization. © 2014 Elsevier B.V.

Xin J.,Hunan Institute of Technology | Huang B.,Hunan Institute of Technology
Journal of Agricultural and Food Chemistry | Year: 2014

A greenhouse experiment was conducted to compare the subcellular distribution and chemical forms of cadmium (Cd) in roots, stems, leaves, and fruits between a low-Cd cultivar (Yeshengchaotianjiao, YCT) and a high-Cd cultivar (Jinfuzaohuangjiao, JFZ) of hot pepper (Capsicum annuum L.). The Cd concentrations in the root's subcellular fractions, and in all chemical forms in roots, were 1.85-4.88- and 1.84-4.90-fold higher, respectively, in YCT than in JFZ. Compared with JFZ, YCT had significantly lower Cd concentrations in the subcellular fractions (1.10-2.42-fold) of stems and leaves and in almost all chemical forms (1.17-2.97-fold) in the stems and leaves. Also, in fruits, the concentrations of Cd in the cell wall and soluble fractions were 1.18-2.24-fold significantly lower in YCT than in JFZ, and there were lower Cd concentrations (1.36-2.08-fold) in the chemical forms in YCT than in JFZ. © 2013 American Chemical Society.

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