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Study on functional clustering analysis methods
SUN Li-rong, ZHUO Wei-jie, WANG Kai-li, MA Jia-hui
Applied Mathematics A Journal of Chinese Universities    2020, 35 (2): 127-140.  
Abstract   PDF (845KB) ( 725 )  
For functional clustering, similarity measure is one of the major approaches. However,
most researches measure the similarity of functional data from a single perspective, using either a
numerical distance approach or a curve shape approach. This paper proposes a new similarity measure
based on extreme point bias compensation. This new measure gives consideration to the numerical
distance and curve shape simultaneously. And the empirical results show the validity of the new
measure. Further, a multifunction clustering analysis method, the function entropy weight method, is
developed, which enriches the functional clustering analysis methods.
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Shape-based BS algorithm for multiple change-points detection
ZHUANG Dan, LIU You-bo, MA Tie-feng
Applied Mathematics A Journal of Chinese Universities    2019, 34 (2): 151-.  
Abstract   PDF (868KB) ( 626 )  
BS algorithm is one of the classical algorithms for multiple change-points detection,
it may bring about too many misjudgments and a high time complexity due to the procedure of global
CUSUM statistic. On one hand, the BS algorithm is an o?-line sequential method, therefore the data
timing information is not fully utilized. On the other hand, the principle of the BS algorithm to detect
the change-points is to maximize the CUSUM statistic, which does not consider the morphological
characteristics of the statistical constituent sequence. In view of these, the paper proposes an improved
BS algorithm, named Shape-based BS algorithm, which is based on local shape recognition. Basing
on the local pattern recognition of statistic sequence not only decreases the computational complexity,
but also avoids mutual interference among change-points, and it could also promote the robustness in
discerning change points. At last, this paper uses Shape-based BS algorithm to reduce the scenarios of
electric power, and achieves satisfactory practical results.
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A kind of deep learning acceleration method for pulmonary nodule detection
Applied Mathematics A Journal of Chinese Universities    2018, 33 (2): 127-139.  
Abstract   PDF (1070KB) ( 407 )  
The deep learning method for pulmonary nodule detection is generally divided into
two stages: candidate nodule detection and false positive nodule elimination. Based on the two-stage
method, an incremental learning acceleration scheme is proposed that integrates new data to improve
the accuracy of the system. The training model of historical data screens new data and selects the
data with poor performance as an input for the continuous training of the two-stage model. The above
methods are tested on LUNA16 and TIANCHI17 two classic data sets. Using only half of the new
ones, the new model can achieve the same e?ect as the traditional two-stage method.
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A modified DBSCAN algorithm and its application in finance
HUANG Han-cheng, JIANG Yu
Applied Mathematics A Journal of Chinese Universities    2020, 35 (2): 169-180.  
Abstract   PDF (410KB) ( 401 )  
This paper presents a modified DBSCAN clustering algorithm with adaptive parameter, and applies it to find potential information clusters of related fund accounts in the stock market.
The algorithm overcome the shortages that parameter ε in the traditional DBSCAN algorithm is oversensitive, and it cannot perform well on multi-densities data sets. Moreover, based on the characteristics
of real data, a new distance is defined to describe the similarity between two funds, which also makes
the modified algorithm better for solving practical problem. Finally, the effectiveness of the modified
algorithm is verified by numerical experiments based on simulated data and real data.
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Empirical likelihood for quantile autoregressive models with dependent auxiliary information
YANG Xiao-rong, XU Shi-zhan, ZHAO Qi-jiong, WANG Li-li
Applied Mathematics A Journal of Chinese Universities    2020, 35 (2): 141-157.  
Abstract   PDF (332KB) ( 338 )  
Quantile autoregressive (QAR) models, commonly adopted in varying-coefficients time
series modelling, has been shown its popularity in both theoretical and empirical studies. Equipped
with autoregressive structure, QAR models sometimes involve extra information in the data collection
process which is known as dependent auxiliary information. An empirical likelihood approach is used
to construct the quantile estimates. The asymptotic normality of the estimates is established conditionally on the lagged values of the response. Under the framework of empirical likelihood method with
dependent auxiliary information, the Wald test statistics are developed for testing the linear restriction
on the parameters. Both the simulation and the empirical study results indicate that the proposed
method yields more efficiency than the traditional one. Therefore, the results for general constant
coefficients QAR model under independent and identically distributed assumptions could be extended
to a class of varying coefficients QAR model with dependent structure.
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GMM estimation of nonparametric spatial lag model
Applied Mathematics A Journal of Chinese Universities    2018, 33 (2): 140-156.  
Abstract   PDF (368KB) ( 300 )  
By relaxing the hypothesis that the in°uence of independent variable in parametric
spatial lag model is a linear or nonlinear function of some known form, a nonparametric spatial lag
model with random independent variables is considered. The GMM estimation method of the model
is constructed, the asymptotic properties of the estimators are derived and the small sample perfor-
mances of the estimates are investigated by Monte Carlo simulation.In addition, the estimation methods
proposed are applied to estimate the growth rate of TFP of China's provinces and municipalities.
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A dual inexact alternating direction method of multipliers for the nuclear norm regularized least squares problem
SHI Bing-bing, WANG Qing-song
Applied Mathematics A Journal of Chinese Universities    2020, 35 (2): 181-190.  
Abstract   PDF (289KB) ( 299 )  
All things in the data age can be described by data record. In data analysis, the problem
of matrix completion is to supplement some missing data. This kind of problem has been studied to a
certain extent. For instance, the desired results are achieved by solving the nuclear norm regularized
least squares problem. In this paper, starting from the duality of the problem, the alternating direction
method of multipliers (ADMM) is used to solve the problem. Under some assumptions, the global
convergence of the inexact dual ADMM (dADMM) are discussed. In the numerical experiments, by
comparing it with the primal ADMM (pADMM) to demonstrate the superiority of the algorithm.
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Symbolic computation of new exact solutions for some nonlinear equations in mathematical physics
ZHOU Kai, YANG Jun, MA Li-yuan, SHEN Shou-feng
Applied Mathematics A Journal of Chinese Universities    2020, 35 (2): 223-234.  
Abstract   PDF (5079KB) ( 265 )  
In this paper, new exact solutions of some nonlinear equations in mathematical physics
are constructed by using the symbolic computation software Maple. Firstly, the two-soliton solution for
an integrable nonlocal discrete mKdV equation is obtained via the Hirota’s bilinear method, and the
asymptotic behavior is analyzed. A kind of explicit expression for the N-soliton solution also is given.
Secondly, abundant families of travelling wave solutions of the multicomponent Klein-Gordon system
and long wave-short wave system are obtained directly by means of the Jacobi elliptic functions. When
the modulus m → 1, those solutions degenerate as the corresponding hyperbolic function solutions
including the bell-type soliton solution.
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Oscillation theorems for third-order nonlinear delay dynamic equations on time scales
FENG Rui-hua, ZHANG Zhi-yu
Applied Mathematics A Journal of Chinese Universities    2020, 35 (2): 211-222.  
Abstract   PDF (246KB) ( 250 )  
This paper is concerned with the oscillatory behavior of third-order nonlinear delay
dynamic equations on time scales. By using Riccati transformation and inequality techniques, the
Leighton-type, Philos-type and Kamenev-type oscillation criteria for a class of delay dynamic equations
on time scales are obtained. Our results improve and generalize the corresponding results in the existing
literatures, and give an example to verify the validity of the obtained results.
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Optimal dividend payment in an insurance company with stationary Hawkes process
CHEN Yi-ling, BIAN Bao-jun
Applied Mathematics A Journal of Chinese Universities    2020, 35 (2): 158-168.  
Abstract   PDF (322KB) ( 242 )  
The optimal dividend payment problem in an insurance company whose surplus follows the classical Cram′er-Lundberg process with cluster claims is considered. A Hawkes process is
introduced so that the occurrence of a claim in the risky asset price triggers more sequent jumps.
Using dynamic programming principle and viscosity solution theory, it shows that the optimal value
function is a viscosity solution of the associated Hamilton-Jacobi-Bellman(HJB) equation. The optimal value function can be characterized as the smallest viscosity supersolution of the HJB equation.
Finally, some numerical results are exhibited and a barrier line strategy is introduced.
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Seymour vertices in a quasi-transitive oriented graph
LI Rui-juan, SHI Jie, ZHANG Xin-hong
Applied Mathematics A Journal of Chinese Universities    2020, 35 (2): 245-252.  
Abstract   PDF (324KB) ( 240 )  
A digraph D is called quasi-transitive if, for every triple x, y, z of distinct vertices of
D such that xy and yz are arcs of D, there is at least one are between x and z. Seymour’s second
neighbourhood conjecture asserts that every oriented graph D has a vertex v such that d+D(x) 6 d++D (x),
where an oriented graph is a digraph with no cycle of length two. A vertex that satisfies Seymour’s
second neighbourhood conjecture is called a Seymour vertex. Fisher proved that Seymour’s second
neighbourhood conjecture restricted to tournaments is true, where any tournament contains at least
one Seymour vertex. Havet and Thomass′e proved that a tournament T with no vertex of out-degree
zero has at least two Seymour vertices. Observe that quasi-transitive oriented graphs is a superclass of
tournaments. In this paper, Seymour’s second neighbourhood conjecture on quasi-transitive oriented
graphs is the core problem. Notice the relationship between Seymour vertices of a quasi-transitive
oriented graph and an extended tournament. It is proved that the conjecture is true for quasi-transitive
oriented graphs. Furthermore, every quasi-transitive oriented graph has at least a Seymour vertex and
every quasi-transitive oriented graph with no vertex of out-degree zero has at least two Seymour vertices.
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Duality theory for the time-varying 4-block problem
GONG Ting, LU Yu-feng
Applied Mathematics A Journal of Chinese Universities    2019, 34 (2): 203-.  
Abstract   PDF (337KB) ( 234 )  
This paper solves the block problems which play a fundamental role in the optimal
control theory under the operator-theoretic framework. Speciˉc duality theory is established for 4-block
problem by computing the appropriate annihilator and preannihilator of subspaces in such optimal
problem. Existence of optimal controllers is ensured and formulas for the performance index are
derived. It is also shown that the known results about duality theories for time-varying 1-block and
2-block problems are both special cases of the presented results in this paper. Moreover, an example
is given to prove that the optimum obtained by duality theory for a compact plant is time-varying allpass.
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The solution of soliton to generalized higher dimensions Klein-Gordon forced disturbed equation
HAN Xiang-lin, WANG Wei-gang, MO Jia-qi
Applied Mathematics A Journal of Chinese Universities    2019, 34 (2): 165-.  
Abstract   PDF (241KB) ( 216 )  
A class of nonlinear generalized forced disturbed Klein-Gordon equation is considered by
using the homotopic mapping method. Firstly, an approximate solution of soliton to typical
nonlinear equation is solved using the method of undetermined coe±cients for the hyperbolic tangent
functions. Then, the approximate solution of soliton to nonlinear forced disturbed equation is obtained
using the homotopic mapping principle. Finally, it is point out that the approximate solution of soliton
is an analytic expression, so we can carry on analytic operation to it. But these can not obtain for the
simple simulate method.
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Possible point spectra of 3 × 3 partial upper triangular operator matrices
WU Xiu-feng, HUANG Jun-jie
Applied Mathematics A Journal of Chinese Universities    2020, 35 (2): 235-244.  
Abstract   PDF (221KB) ( 213 )  
According to the denseness and the closedness of range, the point spectrum of a
bounded linear operator is split into four disjoint parts, i.e., four classes of point spectra. For 3 × 3
upper triangular operator matrices, the possible point spectra SD,E,Fσp,i(MD,E,F )(i = 1, 2, 3, 4) are
given by means of the analysis method and block operator technique.
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A singularly perturbed two parameter solution for the distribution of non Fourier temperature field with a jump in thermal conductivity
BAO Li-ping, LI Wen-yan, WU Li-qun
Applied Mathematics A Journal of Chinese Universities    2020, 35 (2): 199-210.  
Abstract   PDF (257KB) ( 190 )  
In this paper, a temperature field model is constructed by using non-Fourier heat
conduction law, i.e. a class of singularly perturbed hyperbolic equations with small parameters in
an unbounded domain. The singularly perturbed two-parameter hyperbolic nonlinear equations with
discontinuous coefficients are obtained when the heat conduction coefficients jump due to sharp temperature changes. By using the singularly perturbed biparametric expansion method, the asymptotic
solution of the problem is obtained. Firstly, the expansion of the problem is obtained by using the
singularly perturbed method, and the existence and uniqueness of the internal and external solutions
are obtained. The position expression of the jump of the thermal conductivity coefficient is determined
by the method of separating variables, and the slit method is used to connect the slits of the two sides of
the jump position of the thermal conductivity coefficient, thus the asymptotic expansion of the solution
is obtained. Secondly, the uniform validity of the asymptotic solution is obtained by estimating the
residual term, and the distribution of the complete temperature field is obtained.
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Cauchy integral formulas for two kinds of functions in Clifford analysis and the related problems
CHEN Xue, ZHANG Ting-ting, XIE Yong-hong
Applied Mathematics A Journal of Chinese Universities    2019, 34 (2): 190-.  
Abstract   PDF (255KB) ( 185 )  
This paper mainly studies Cauchy integral formulas for two kinds of functions and
the related problems. Firstly, the Cauchy integral formula for right hypergenic functions in Clifford
analysis is given. Then, the properties of the right hypergenic quasi-Cauchy type integral are studied.
Finally, the Cauchy integral formula for bihypergenic functions in Clifford analysis is given.
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Uniform topological spaces base on normal fuzzy ideals in negative non-involutive residuated lattices
LIU Chun-hui
Applied Mathematics A Journal of Chinese Universities    2019, 34 (2): 227-.  
Abstract   PDF (276KB) ( 174 )  
Topological structure is one of important research contents in the field of logical algebra.
In order to describe the topological structure of negative non-involutive residuated lattices, based
on the congruences induced by normal fuzzy ideals, uniform topological spaces are established and some
of their properties are discussed. The following conclusions are proved: (1) every uniform topological
space is ˉrst-countable, zero-dimensional, disconnected, locally compact and completely regular. (2) a
uniform topological space is a T1 space i? it is a T2 space. (3) the lattice and adjoint operations in a
negative non-involutive residuated lattice are continuous under the uniform topology, which make the
negative non-involutive residuated lattice to be topological negative non-involutive residuated lattice.
Meanwhile, some necessary and sufficient conditions for the uniform topological spaces to be compact
and discrete are obtained. Finally, the relationships between algebraic isomorphism and topological
homeomorphism in topological negative non-involutive residuated lattice are discussed. The results of
this paper have a positive role to reveal internal features of negative non-involutive residuated lattices
on a topological level.
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Fast efficient estimation and application of partially linear single index model with fixed effects
DING Fei-peng, CHEN Jian-bao
Applied Mathematics A Journal of Chinese Universities    2019, 34 (2): 127-.  
Abstract   PDF (481KB) ( 162 )  
By combination of least square vector machine (LSSVM) with quadratic inference func-
tions (QIF), this paper construct a new estimation method for partially linear single index panel model
with fixed effects when responses from the same cluster are correlated. Under some regular condition,
asymptotic normality of parametric estimators and convergence rate of non-parametric estimator are
derived. The ˉnite sample performances of the proposed method are investigated by Monte Carlo simu-
lation under di?erent correlation structures, and compared with penalized quadratic inference functions
method (PQIF). The proposed estimation techniques are applied to analyse the relationship between
population structure and residents’consumption rate. Our research results show that the e±ciency
of estimators are improved by the proposed method, application e?ects are good, program operation
has high speed, it is particularly suitable for analysis of linear, nonlinear relationship among economic
variables and big data.
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The robustness of two fuzzy reasoning methods
WANG Yuan-yuan, PEI Dao-wu
Applied Mathematics A Journal of Chinese Universities    2019, 34 (2): 218-.  
Abstract   PDF (233KB) ( 157 )  
Based on logical similarity and residual implications, the paper discusses the robust-
ness of two important reasoning methods, the ˉve implication inference method (QIP) and the similarity
inference method (FSI). The concrete results of the robustness of QIP method under four common im-
plications are given, based on the revised Kleene implication the FSI's robustness conclusion, and a
preliminary comparison of the robustness of these two inference methods.
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Global analysis of a class of tumor-immune system dynamics
HUANG Pei, LIN Xiao-lin, LI Jian-quan, SONG Xiu-chao
Applied Mathematics A Journal of Chinese Universities    2019, 34 (2): 181-.  
Abstract   PDF (262KB) ( 149 )  
Based on the fact that tumor cells not only stimulate the proliferation of immune
effector cells but also have the inhibiting effect on the growth of the cells, a tumor-immune dynamical
model is described by expressing the comprehensive effect of tumor cells on immune system with a
positive or negative action rate coefficient. By investigating the global dynamics of the model, it is
found that the saddle-node bifurcation and the bistable phenomenon may occur, which implies that
that the final state of tumor development depends on the initial state, and the corresponding threshold
conditions are obtained. And the effect of the intrinsic input of effector cells and the action rate
coefficient of tumor cells on effector cells on the dynamics of the model is analyzed. The obtained
results show that the model may have complex dynamical behaviors when the inhibition effect of
tumor cells on effector cells is strong enough.
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