ISSN 0253-2778

CN 34-1054/N

2014 Vol. 44, No. 2

Display Method:
A Morawetz estimate related to almost periodic solutions and its application to Schrdinger equations
ZHENG Yunrui
2014, 44(2): 87-92. doi: 10.3969/j.issn.0253-2778.2014.02.001
Under the condition ‖u0‖H·≤‖W‖H·, a new type of Morawetz estimate related to almost periodic solutions was given to exclude the existence of a special minimal blowup solutions for three dimentional energy-critical focusing NLS in the radial case, where W is the ground state.
Equivalent conditions of Devaney chaos on the hyperspace
LI Jian
2014, 44(2): 93-95. doi: 10.3969/j.issn.0253-2778.2014.02.002
Let T be a continuous self-map of a compact metric space X. The transformation T induces naturally a continuous self-map TK on the hyperspace K(X) of all non-empty closed subsets of X. It is shown that the system (K(X),TK) is Devaney chaotic if and only if (K(X),TK) is an HY-system if and only if (X,T) is an HY-system, where a system is called an HY-system if it is totally transitive and has dense small periodic sets.
An upper bound for the Harary index of a connected graph and the corresponding extremal graph
LI Xiaoxin, ZHA Shuping, FAN Yizheng
2014, 44(2): 96-100. doi: 10.3969/j.issn.0253-2778.2014.02.003
The Harary index of a graph is defined as the sum of reciprocals of distances between all pairs of vertices of the graph. The graph(s) with maximum Harary index among all graphs with given order and diameter was characterized, and an upper bound for the Harary index in terms of diameter was provided. In addition, the connected graphs of order n with the second maximum and the third maximum Harary indices were characterized, respectively.
Variable selection and shrinkage quantile estimation for censored regression model
YE Renyu
2014, 44(2): 101-105. doi: 10.3969/j.issn.0253-2778.2014.02.004
Censored regression (“Tobit”) model is a kind of limited dependent variable model widely used in econometrics research. Based on the quantiles estimation and the smoothly clipped absolute deviation (SCAD), a method for variable selection and shrinking estimation was presented, which selects the non-zero coefficients corresponding to the significant variables and simultaneously gives a consistent estimate of the parameters. In addition, the variable selection possesses the oracle properties. Finally, numerical studies were conducted to evaluate the performance of the proposed method for censored regression model.
Vapor-phase synthesis of single-crystalline Ag nanowires and their SERS properties
LI Zhi, ZHU Wei, YU Qingxuan, YANG Qianhui, SHAO Zhibin, LOU Liren
2014, 44(2): 106-111. doi: 10.3969/j.issn.0253-2778.2014.02.005
Single-crystalline Ag nanowires with a face-centered cubic (fcc) crystal structure were synthesized inside Ag/ZnO coaxial nanocables by the vapor-liquid-solid (VLS) mechanism through a thermal evaporation route. The confinement of the ZnO shell was believed to be responsible for the emergence of the single-crystalline phase. Ag nanowires with different diameters could be obtained by etching Ag/ZnO coaxial nanocables with modulated core-shell ratio determined by Ag concentration in the source. These high-quality silver nanowires were explored as sensitive substrates of surface enhanced Raman scattering (SERS).
Characterisics of hydrogen and oxygen isotopes of deep ground water in the Panxie mining area in Huainan Coalfield
GE Tao, CHU tingting, LIU Guijian, FAN Xiang, WU Dun
2014, 44(2): 112-118. doi: 10.3969/j.issn.0253-2778.2014.02.006
34 water samples (i.e, rainfall, surface water, groundwater from the Taiyuan Formation limestone aquifer, the Ordovician limestone aquifer and the Cambrian limestone aquifer) were collected from the Panxie mining area of Huainan Coalfield,and TDS (total dissolved solids), hydrogen and oxygen isotopes (δD and δ8O) were determined. Different evaporation slopes and deuterium excesses of individual aquifers indicate that there are different evaporation rates and residence times among them. The Taiyuan Formation limestone aquifer has a stronger hydraulic connection with the surface water compared with the Ordovician limestone aquifer. Isotope composition of the limestone water is associated with mixing between shallow recharge groundwater and a contribution including mineralized fluids from the deep aquifer. The primary factor responsible for δD and δ8O excursion may be attributed to water-rock interaction in the limestone aquifer.
Distribution and ecological risk assessment of trace elements in mining soil in Guqiao Coal Mine, Huainan Coalfield
LU Lanlan, LIU Guijian, WANG Xingming, WANG Jie
2014, 44(2): 119-127. doi: 10.3969/j.issn.0253-2778.2014.02.007
Environmental-sensitive trace elements would be released, migrate and be enriched in the surrounding soil environment during the process of coal mining and utilization. Soil samples from the surface and profiles were collected at different distances to the coal gangue pile of Guqiao Coal Mine and the concentrations of Zn, Pb, Cd, Ni, Cr and Cu were determined by inductively coupled plasma-optical emission spectrometry (ICP-OES). The distribution and enrichment were accordingly investigated and the ecological risk was assessed as well. In addition to using geoaccumulation index and ecological risk index, geoaccumulation index and Nemerow index were combined to evaluate the contamination of trace elements in this area. Results show that concentrations of Zn, Pb, Cd, Ni, Cr and Cu in soils decrease with increasing distance,but change little with increasing depth. The soil is not contaminated by the trace elements except Cd.
Compact image representation based on variability analysis
ZHAO Xin, HUANG Kaiqi, TAN Tieniu
2014, 44(2): 128-137. doi: 10.3969/j.issn.0253-2778.2014.02.008
Image representation is the most fundamental and important aspect in image classification tasks. Most existing image representation methods use quite high dimensional feature vectors for image representation in order to achieve desired performance, which results in an inevitable drawback which is a classification problem with very high-dimensional feature vectors. Meanwhile, the existing methods have not considered image variations in image representation. Thus, an image representation method was proposed to model the variability in image classification. First, a Gaussian mixture model (GMM) was used to model the low-level visual feature vectors. Then, the sufficient statistics of images were constructed. Finally, the proposed variability analysis was utilized to decompose the sufficient statistics, and a compact image representation was obtained by means of partial least square regression. The proposed method not only achieves better performance on the public image classification datasets, but also reduces the burdens of classifier training and feature storage.
Energy efficiency priority admission control and service transfer algorithm based on Markov decision processes in hierarchical networks
PAN Jun, ZHANG Wenyi
2014, 44(2): 138-146. doi: 10.3969/j.issn.0253-2778.2014.02.009
In a hierarchical cellular network environment, both macrocell and femtocell are deployed to improve network performance. The admission control problem for hierarchical network was addressed when all types of handovers were considered. The admission control and service transfer problem was formulated as a Markov decision process (MDP) optimization problem with constraints on the blocking probability and dropping probability and the objective of maximizing the average system energy efficiency reward function. When there are idle resources in a femtocell, the services connected to a macrocell with users located in the coverage of the femtocell could be chosen to be handed over to the femtocell. The optimal policy is obtained by solving a linear programming problem. Simulation results show that the proposed energy efficiency priority admission control and transfer strategy effectively improves the resource utilization of the femtocell with the maximum reward, and decreases blocking probability and dropping probability. Meanwhile, reducing resource utilization of the macrocell will make it possible to provide services to users within a larger coverage area.
A synthetic aperture beam-former for ultrasound imaging based on FPGA
WANG Dongya, YU Chenglong, PENG Hu
2014, 44(2): 147-152. doi: 10.3969/j.issn.0253-2778.2014.02.010
Synthetic aperture ultrasound imaging is often used in modern digital medical ultrasound imaging for its high-resolution and high-contrast images with a small number of transducers. But the traditional synthetic aperture method is very complex and limited in real-time imaging. Contrast to the non-uniformly sampling data imaging from customized target area, a beam-forming algorithm of the uniformly sampling system applied to a multi-element synthetic aperture ultrasound imaging system using a high speed digital circuit was designed and implemented in a hardware circuit based on field programmable gate array(FPGA).The system was composed of one FPGA EP2C8Q208C8 of Cyclone Ⅱ series from Altera corporation and one synchronous dynamic random access memory (SDRAM) chip to store echo data, which were delay superimposed and weighted and sent to PC via USB. With the pipeline architecture and the parallel nature of FPGA, the beam-forming algorithm was implemented. The test results demonstrate that the system is accurate and effective and can be applied to real-time ultrasound imaging.
A two-level pupil location method relying on 3D eyeball model
XIA Xiaobao, LI Bin
2014, 44(2): 153-159. doi: 10.3969/j.issn.0253-2778.2014.02.011
As a key part of the head-mounted eye tracking system, pupil detection not only affects system accuracy, but also system stability. However, the problem of eyelid occlusions arises when eyeball moves. To solve this problem,a Two-Level pupil detection method was proposed. The first level utilizes the improved starburst method to extract pupil edge points and then check whether the pupil is shaded by eyelid. If its not the case, pupil detection ends, otherwise the second level detection is conducted. In the second level detection, improved ellipse template matching method is applied. Unlike other ellipse matching methods, this method is based on a 3D eyeball model. With eyeball parameters, this method estimates ellipse minor-major axis rate and angle of rotation in advance, and then decreases the spatial complexity from five dimensions to three, thus improving matching efficiency. With our method, the pupil can be easily rapidly detected under eyelid occlusions.
Automatic dendritic spine detection and analysis in 3D microscope images
WANG Qian, LI Yang, DU Sidan
2014, 44(2): 160-164. doi: 10.3969/j.issn.0253-2778.2014.02.012
Fluorescence microscopy imaging is one of the important methods for the study of the dendritic spine structures. Most of the current morphologic analyses in low SNR images involve a significant component of manual labor and is susceptible to operator bias. An algorithm based on endpoint match-searching and segmentation-sampling curve fitting was presented to automatically detect the edge of the dendrite, separate dendritic spines and calculate their size, number and density in complex images. Analysis of the results shows that it provides an efficient, accurate tool for dendritic spine analysis.
Research on positioning control of the precision positioning system of the grating ruling machine
SHEN Yuan, WANG Yiying, ZHU Chang'an, QI Xiangdong
2014, 44(2): 165-170. doi: 10.3969/j.issn.0253-2778.2014.02.013
The control and experiment research of the precision positioning system of the grating ruling machine were presented. Considering the non-linearity and time-variation characteristics of the precision positioning system, PID feedback control based on BP neural network was utilized in the positioning system. With the functions of self-learning,the parameters of the PID controller were adjusted in real time, and precision positioning could be realize by the PID controller. Experimental result shows that a positioning accuracy within 5 nm was achieved.