ISSN 0253-2778

CN 34-1054/N

2017 Vol. 47, No. 9

Display Method:
Original Paper
Shape approximation via sparse optimization
HU Chao, ZHANG Juyong
2017, 47(9): 713-720. doi: 10.3969/j.issn.0253-2778.2017.09.001
A novel sparse optimization based shape approximation method to represent a 3D model using planar pieces was introduced, which enables a designer specified reasonable and fixed number of planes to be obtained. The method first gives a L0 minimization algorithm to optimize the face normal of the input model and then updates the vertex position based on filtered normal information. Next, a simple clustering method was proposed to obtain a clustering model. To this end, a boundary vertex gradient minimization algorithm was developed for solving a global energy function to represent the input model. A large number of experiments show the validity of the model and algorithm as well as the stability of the algorithm when solving mesh simplification problems in dynamic environments.
Face sorting and stripe texture mapping of triangle mesh based on spectral decomposition
LI Yan, ZHOU Shizhe, DENG Jiansong
2017, 47(9): 721-728. doi: 10.3969/j.issn.0253-2778.2017.09.002
The layout of the triangle face in the existing mesh file format is often out of order, which brings great difficulties in the subsequent processing of large meshes. A useful approach later proposed based on spectral decomposition of dual meshes, did lead to a good face order. However, the order was only partial. In view of the drawback of the algorithm, a unique traversal algorithm was presented here which can get a triangular mesh with a total ordered layout of the faces. Furthermore, a series of ordered triangle strips were obtained, and the geometric and topological properties of the original input mesh didn’t change in the process. Finally, the triangle strips were parameterized, and the stripe texture mapping was applied. Experimental results show that the method is superior to the spectral decomposition method and can generate a satisfactory triangular strip.
A weak-Lp Prodi-Serrin type regularity criterion for electro-hydrodynamics
SHAO Guangming
2017, 47(9): 729-732. doi: 10.3969/j.issn.0253-2778.2017.09.003
Regularity criteria for weak solution of the electro-hydrodynamics was studied. It was proved that the solution (u,n,p,Ψ) remains strong on [0,T] if u∈Ls(0,T;Lr,∞(Ω)) or ‖u‖Ls,∞(0,T;Lr,∞(Ω))≤C, where (3/r)+(2/s)=1 and r∈(3,∞], C>0 depending only on r and Ω.
The maximum Laplacian separators of bicyclic and tricyclic graphs
YU Guidong, HUANG Dongming, ZHANG Wuxiao, WANG Chen
2017, 47(9): 733-737. doi: 10.3969/j.issn.0253-2778.2017.09.004
Let G be an undirected simple graph of order n, L(G) be the Laplacian matrix of G, and μ1(G)≥μ2(G) ≥…≥μn(G) be the eigenvalues of L(G). The Laplacian separator of G is defined as SL(G)=μ1(G)-μ2(G). Here the maximum Laplacian separators of bicyclic and tricyclic graphs of a given order were studied, and the corresponding extremal graphs were characterized.
The asymptotic solutions to a class of nonlinear disturbed evolution equations
FENG Yihu, LIU Shude, MO Jiaqi
2017, 47(9): 749-754. doi: 10.3969/j.issn.0253-2778.2017.09.006
A class of nonlinear evolution equations was considered. Firstly, introducing a travelling wave transform, the non-disturbance case was discussed by employing the undetermined coefficient method of the hyperbolic functions and solitary exact solution to the corresponding nonlinear equation was obtained. Then, the solitary travelling wave asymptotic solution to the original nonlinear disturbed evolution equation was founded by using the generalized variational iteration method. Finally, an example was given to show the simplicity and feasibility of the asymptotic solitary solution.
Least product relative error estimation with right censoring
HU Dahai, ZHANG Weiping
2017, 47(9): 755-761. doi: 10.3969/j.issn.0253-2778.2017.09.007
The multiplicative regression model with right censoring was considered. Under the random right censorship, the criterion of the least product relative error (LPRE) was extended to the case with right censoring. Under some regular conditions, the consistency and asymptotic normality were established. Finally, some simulations were conducted to examine the finite performance of the proposed method.
Statistical analysis of effects of freshmen’s mental health on grades:A UPI-based retrospective study
DING Shu, LIU Fen, MIAO Baiqi, KONG Yan
2017, 47(9): 762-769. doi: 10.3969/j.issn.0253-2778.2017.09.008
Methods of mathematical statistics were applied to evaluate the effects of categorical data, such as freshmen’s mental health, on average grades of some terms and average grades of some courses, thereby providing information on the psychological mechanism of early warning and assistance to all concerned. The analyzed data was collected from the University Personality Inventory results and the examination results of students enrolled in 2002 into a certain key science and engineering university. The results show that students who have suicidal tendency, or regard their past and family life as unfortunate, score obviously lower than other students; and that those who had the experienced syncopy or spasm before entering college also performed poorly. Concentration is an important guarantee of achieving good grade in college.
Modelling and forecasting of call center arrival process
HUO Jiamian, XIE Jingui
2017, 47(9): 770-777. doi: 10.3969/j.issn.0253-2778.2017.09.009
Fitting arrival process and forecasting future arrivals are crucial to staffing and scheduling in call centers. According to different stages of a call center, arrivals are classified into IVR arrival and agent arrival. Non-homogeneous Poisson process has been widely used overseas for modeling stochastic agent arrival process. However, this study initially proposed IVR arrival fitting and forecasting. The IVR arrival process of this call center appears to be “overdispersed” when comparing the mean arrival rate and its variance with the corresponding Poisson process. Therefore, time series was used to model and predict the IVR arrival process. White noise test of residuals was applied and the MAE (mean absolute error) was adopted to evaluate the goodness of fit. The results show that ARIMA (1,0,1) is preferable for predicting the IVR arrival in a short period of normal days and Winters is preferable for the Spring Festival period. Finally, the regression method was employed to describe the relationship between IVR arrival and agent arrival, and predict the agent arrival.
Co-movement between the price of gold and foreign exchange rate during the financial crisis
PAN Wanbin, XIONG Xinwei
2017, 47(9): 778-787. doi: 10.3969/j.issn.0253-2778.2017.09.010
The relation between the price of gold and foreign exchange rate was studied based on a model of quantile association regression. It was found that the price of gold and foreign exchange rate are usually negatively related. But during the financial crisis, evidence of a positive tail dependence was found, because of investors’ risk aversion. Furthermore, existence of symmetric extreme tail dependence between the price of gold and the exchange rates of the Euro, Australian dollar, British pound and Canadian dollar during the crisis, but asymmetric extreme tail dependence existed in the long term. Empirical findings also indicate that the dependence strength significantly increases on upper and lower quantiles.