Table of Content

25 March 2019, Volume 58 Issue 2

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A similarity metric algorithm for multivariate time series based on information entropy and DTW

QIAO Meiying；LIU Yuxiang；TAO Hui

2019, 58(2):  1-8.  doi:10.13471/j.cnki.acta.snus.2019.02.001

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This paper presents a method based on information entropy and dynamic time warping (DTW) to measure the similarity of multivariate time series. Firstly, DTW based on the Mahalanobis Distance considers the interrelationships among the variables of the multivariate time series, through the dynamic warping to align time series of different length. Secondly, adapting the information entropy theory, the Mahalanobis distance matrix is learned by minimizing the loss function, which can obtains the global optimal Markov matrix. In order to verify the effectiveness of the proposed algorithm, the five data sets in the UCI data set were used to classify through the nearest neighbor classification algorithm. Experimental results show that this method has higher classification accuracy and less time consumption than other methods, which proves the effectiveness of the proposed method.

Scene classification algorithm based on adaptively regional supervision

CHEN Zhihong；HU Haifeng； MA Shuiping；YU Aobo

2019, 58(2):  9-14.  doi:10.13471/j.cnki.acta.snus.2019.02.002

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Deep Convolution Neural Network (DCNN) is a popular scene classification method. However, with the neural network deeper and wider, the difficulty of training network also increases. Some scholars have proposed crop images randomly to reduce the difficulty of network training, which will reduce the relevance of the cropped image to the label. To solve this, we propose a scene classification algorithm based on adaptively regional supervision, which is constructed by three parts: heat map generation layer, adaptively supervised cropping layer, and classification layer. The algorithm generates heat map for each image, adaptively crops the image based on the heat map, and finally classifies the cropped images, which improves the relevance of the cropped images to labels. Experiments on the 15-Scene and MIT Indoor datasets show our algorithm outperforms the original network architecture in training efficiency and recognition performance, which shows the accuracy and robustness of our algorithm.

CFD simulation and analysis of smoke dispersion in a subway fire

CHEN Kecheng；XIE Jiabin；YAO Qinghe

2019, 58(2):  15-22.  doi:10.13471/j.cnki.acta.snus.2019.02.003

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To investigate the flow regularity of smoke in the subway station, Fire Dynamics Simulator is used to study the fire smoke spread in the Higher Education Mega Center North Station. The boundary conditions required for numerical simulation are determined based on the measured temperature and air velocity in the subway station. Large Eddy Simulation (LES) and Massive Passage Interface (MPI) are used to do realistic view simulation of the subway platform. As the result shows, when a fire breaks out in the middle of the platform, smoke concentration, CO concentration and temperature on the left part of the platform are about 133 percent, 75 percent and 41 percent respectively higher than those on the right part. Therefore, the right part of the platform is more secure for personnel evacuation.

WPT system based on singlestage ACAC converter

HUANG Yaqi； XIAO Wenxun

2019, 58(2):  23-28.  doi:10.13471/j.cnki.acta.snus.2019.02.004

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The design and implementation of the high frequency power supply, which offers a high frequency current to the primary winding, are of great importance in magnetic coupled Wireless Power Transfer (WPT) system. But the power supply, used in conventional WPT system, is comprised of rectifier and high frequency inverter, has the shortcoming of comparatively complicated structure and control. So, this paper proposes a novel single-stage AC-AC resonant converter. The proposed converter, converting the line source directly into high frequency source applied to WPT system via one stage conversion, has the advantages of less power elements and higher power factor. Experiments are carried out to verify the effectiveness of the proposed converter utilized in the WPT system with SS topology.

The reaction mechanism of the NO_x emission and combustion characteristics of the natural gas with diluents

LIN Zirong；HUO Jiepeng；LI Xing

2019, 58(2):  29-36.  doi:10.13471/j.cnki.acta.snus.2019.02.005

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The effect of different diluents on the NO_x  emission of the combustion of natural gas with CO₂ and N₂ was studied with premixed methane/air/diluent flame. The chemical effect and thermal effect of CO₂ on the NO production was revealed via conducting reactionpath analysis. The numerical results show that: 1) CO₂ is more effective than NO in emission reduction. The chemical effect is achieved by consuming larger part of CH₂(s) in the flame zone, leading to smaller NO production subsequent to lower CH concentration; 2) compared to the chemical effect, the thermal one plays a more important role in NO emission by reducing the adiabatic flame temperature of the mixture; 3) the introduced diluents enlarge the ignition delay time slightly and greatly reduce the laminar flame speed of the mixture, indicating that low NO_x  emission characteristic of diluents accompanies with significant inhibiting effect on the combustion of the mixture.

Calibration of mesoscopic traffic flow model based on distributions of single-vehicle speed

YANG Yunlin；HE Zhaocheng；WANG Yimin

2019, 58(2):  37-44.  doi:10.13471/j.cnki.acta.snus.2019.02.006

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Parameters of microscopic traffic simulation model could be calibrated using the mean error as goodness of fit. However, due to the unmatched specification of model with the granularity of data and lack of regard for the individual information, optimization algorithm might be misled to find unreasonable solutions. To deal with such issue, mesoscopic model was chosen for its simpler specification and the goodness of fit function based on the distribution of singlevehicle speed is proposed in this paper. Then, a case study was employed for calibration of simulation model by using the network of inner ring road, Guangzhou. Moreover, a traditional calibration method was used for comparison and analysis. Results show that the new measure of goodness of fit outperform the traditional one in terms of the calibration effect, parameters rationality and optimization efficiency, which reveal that the proposed method has the potential to be feasible and popularized.

The type and morphologic characteristics of Yuanshui river placer diamonds in Hunan and their significance in revealing origin

BO Haonan；QIU Zhili；LU Taijin； CHEN Hua；HUANG Yuancheng；DENG Xiaoqin；MA Ying；YANG Han；QIAN Jiaqi

2019, 58(2):  45-57.  doi:10.13471/j.cnki.acta.snus.2019.02.007

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Primary crystal & face morphology of natural diamonds can reflect their geochemical characteristics and forming conditions at deep mantle to some extent, and secondary micromorphology superimposed in magmatic transit to surface and in stream transportation can be used to explore their postforming experience and the remaining time of diamonds on earths surface. This paper presented the types based on infrared spectrometer analysis, crystal & face morphology of 297 diamonds from modern deposits along Yuan river basin in Hunan. The  results show that 282 diamonds belong toⅠaAB type, 3 diamonds areⅠaB type, and 5 diamonds are Ⅱa type. Morphology analysis results show that Hunan diamonds have clear and well preserved surface erosion possibly reflecting a rapid magma transit from far deep to the surface. Triangular and occasional hexagonal etch pits are common on crystal face (111) of some diamonds indicating a forming environment of oxidizing H₂Orich metasomatic fluid/melts in the mantle during diamond resorption events. One diamond shows extraordinary crystalline form like a diver helmet which was only found in Kalimantan diamonds. Hunan diamonds show clear similarity with Western Australia diamonds in crystal morphology, nitrogen contentbased diamond type, inclusions and carbon isotopes. These evidences suggest possible genetic relationship between Hunan diamonds and Western Australia diamonds, and therefore Hunan diamonds were formed not earlier than the Paleoproterozoic, and more likely related to the subduction in Neoproterozoic.

Diurnal characteristics of autumn ASD-aerosols over Guangzhou

TANG Yuming；DENG Ruru；XU Minduan；WU Yi

2019, 58(2):  58-67.  doi:10.13471/j.cnki.acta.snus.2019.02.008

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Aerosol optical parameters can indicate content and distribution of aerosol particles, and turbidity of atmosphere, which are of great significance to the research of aerosols. ASD FieldSpec3 spectroradiometer was used to measure the diurnal variation of aerosol particle contents over Guangzhou city on October 23, October 31, November 1, 2017 in typical autumn for inverting and analyzing its aerosol optical depth, Angstrom parameter, volume concentration and number concentration. The results showed that: 1) The daily variation of AOD was not notable and slightly different from day to day, but generally showed an increase trend.
The wavelength indices of each day were high indicating that fine particles were principal components of aerosol particles in typical autumn day.  The turbidity coefficient was low showing that the atmosphere was in good condition.2) The AOD, volume concentration and number concentration of aerosol particles over Guangzhou increased continuously from 9 o’clock and reached a maximus at 15 o‘clock, which were possibly attributed to human activities. 3) The aerosol particles over Guangzhou showed a bimodal pattern in volume concentration. They were mainly composed of water-soluble and soot fine particles with sizes less than 0.1 μm, and showed a stable proportion between various aerosol particles, which did not change with time, indicating a relatively fixed pollution source. In addition, the slight amount of dust and  maritime particles represented that overall aerosol of Guangzhou was a hybrid  type made up of industrial and ocean type.

The structure features of urban power space in the Yangtze River Delta based on the network of financial enterprise organization

REN Yawen；CAO Weidong； LI Yingying

2019, 58(2):  68-76.  doi:10.13471/j.cnki.acta.snus.2019.02.009

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The power space of urban agglomeration is the status of individual cities in a regional spatial network, and the control scope and degree of control of individual cities within the region are quantified based on the associated network. According to the theory of power space and space production, crawled directory data of financial enterprise headquarters and their branches in the Yangtze River Delta region are used to construct spatial attribute database through ArcGIS and UCINET, and the power space structure of urban agglomeration by network analysis method. The results showed that: (1) The control index of Shanghai reached 120.72, and the remaining 25 cities showed less than 50 except Nanjing; the central index of Shanghai reached 0.263 2, and Nanjing, Hangzhou and Hefei were 0.132 4, 0.098 8 and 0.044 1, respectively. The gap in power space between cities is significant, completely forming a “central-edge” power space structure and presenting a polarization trend. (2) The Condensed-Subgroups of the power space are clearly defined: the correlation strength between Zhejiang, Anhui provinces and Jiangsu Province is lower than 100 and 200, respectively, while the correlation strength between Shanghai and region of “SouthJiangsu Province” is close to 400. (3) The significant difference between centrality, control power and cohesive subgroups indicates that the spatial pattern of urban power is a non-equilibrium form under the flow of capital elements, and also an important result of the production of material and institutional space. The above reveals that in the process of spatial production of urban agglomerations, the city interacts as a power subject at the moment, and the profitseeking tendency of financial capital further expands the differences in urban power in the network.

The spatial-temporal features of population growth in fast immigrant city Shenzhen

YANG Gao； ZHOU Chunshan； WANG Shaojian

2019, 58(2):  77-88.  doi:10.13471/j.cnki.acta.snus.2019.02.010

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The growth pattern and distribution characteristics of population in Shenzhen are analyzed using the statistical yearbook and the data from the 3^rd to 6^th census by mathematical statistics and GIS spatial analysis. The main results are as follows: (1) As a rapid immigration city, the population growth of Shenzhen was mainly influenced by economic factors and secondly by political factors. (2) The change of the permanent population is consistent with the change of the migrant population, and the fluctuation of population growth is relatively large. The dispersion coefficients are 0.54 and 0.66 from 1990 to 2000 and from 2000 to 2010, respectively. The outlying urban areas have mostly rapid growth in population, but those relatively remote areas show negative growth. (3) The “hot zones” are around the downtown areas; the “cold zones” lie mainly in the eastern region and Guangming new district. In addition, the index of population concentration is low and the distribution is relatively dispersed. The mean pointer center is showing the trend of the northwest direction. The spatial distribution of population density changed from “1 high center” to “1 high center+1 peripheral center” and then to “1 high center+2 peripheral center”. (4) The population growth of Shenzhen is stepping into maturity period from fast growing period, and the pattern of population distribution is in a transitional period from the absolute concentric to the relative concentric period.

Spatial-temporal distribution of freezing disasters in Jin-Shan-Inner Mongolia adjacent area from 180 to 1911

DANG Qun；YIN Shuyan；XU Zhaohong

2019, 58(2):  88-95.  doi:10.13471/j.cnki.acta.snus.2019.02.011

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Jin-Shan-Inner Mongolia adjacent area, a climate transition zone, is sensitive to climate change. Based on the statistics and analysis of the historical documents about freezing disasters in Jin-Shan-Inner Mongolia adjacent area, spatialtemporal distribution of the frequency, countytimes and intensity were analyzed in the light of the methods of least squares and wavelet analysis. The results show that there were 144 years with freezing disasters in 960 counties of Jin-Shan-Inner Mongolia adjacent area from 180 to 1911. Autumn and summer were frequently prone to disaster. The disasters occurred in Ming and Qing Dynasties accounted for 65.3%, with 64.2% of counties suffered. Freezing disasters in historic periods showed a rising trend, experiencing three stages, namely, low frequenting, increasing and rapidly fluctuating. Wavelet analysis shows that there existed freezing disaster cycles of 200, 110, 80, and 20 years in history with a principal cycle of 200 years. The spatial distribution of the historical freezing disasters varied distinctly，Yulin was the high-frequency disaster center, while Xingxian, Hequ, and Liulin were the low-frequency disaster centers. Climate change and population density, the degree of agricultural development jointly affected the occurrence of freezing disasters. The cold climate and transition have more impact on the extent of freezing disaster, population density and production development affect the frequency of disaster.

Polyphenols from Dendrobium loddigesii and their biological activities

LI Xuewen；CHEN Huiping；HE Weibo；YANG Wenling；NI Feiyu；HUANG Ziwen； HU Haiyan； WANG Jun

2019, 58(2):  96-102.  doi:10.13471/j.cnki.acta.snus.2019.02.012

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To study the polyphenols from Dendrobium loddigesii and their biological activities, the 80% acetone extract from D. loddigesii was isolated and purified by chromatography techniques; the structures of obtained compounds were identified with spectroscopic techniques; the antioxidative, α-glucosidase inhibitory and antiinflammatory activities of compounds were evaluated. Fifteen compounds were isolated and identified as chrysotoxol A (1), neoechinulin A (2), 3,6,9trihydroxy-3,4-dihydroanthracen-1(2H)-one (3), 4,4′=dihydroxyl-3,5-dimethoxylbibenzyl (4), naringenin (5), 5,4′-dihydroxy-7,3′,5′-trimethoxyflavanone  (6), 5,7,4′-trihydroxy-3′,5′-dimethoxyflavanone (7), batatasin-III (8), 3,3′,5-trihydroxybibenzyl (9), trigonopol B (10), syringaresinol (11), 2,4,7-trihydroxyl-9,10dihydrophenanthrene (12), loddigesiinol B (13), loddigesiinol I (14), loddigesiinol J (15),respectively. Compounds 1-11 among them were isolated from D. loddigesii for the first time. The biological activities of compounds 1-4, 6, 7 and 12 were evaluated for the first time under trial conditions. It was reported for the first time that compounds 1, 3 and 12 had a strong antioxidant activity, compounds 1 and 9 showed a strong α-glucosidase inhibitory activity, and compounds 1, 12, 14  and 15 had a strong anti-inflammatory activity.

The application of freeze-dried and cross-linked lignin in water treatment

CHEN Fenggui; LI Jiao; HUANG Lu; LIU Zhiheng; LI Xiaoyan; YANG Li

2019, 58(2):  103-109.  doi:10.13471/j.cnki.acta.snus.2019.02.013

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Lignin is a natural chemical containing abundant catechol groups, which can be used to remove the organic pollutant and heavy metal ion. In order to avoid its dispersion in water, lignin was cross-linked with glutaraldehyde (GA). Furthermore, lignin was demethylated to enhance the phenol group in the structure, and surface area of modified lignin was also significantly increased by freeze-drying method from 0.002 m²/g to 0.826 m²/g, which remarkably improves the adsorption property of lignin on rhodamine B with the adsorption capacity increased from 2.0 mg/g to 19.2 mg/g.

Identification of human EGFR high-affinity mutant E40V via directed evolution in vitro

SUN Yujie; YANG Nanyan; OU Jinxin; LI Fei; HUANG Xueying; WANG Qinghuai; LIU Jian; WANG Qianqian; LIU Xing; ZHANG Qing

2019, 58(2):  110-120.  doi:10.13471/j.cnki.acta.snus.2019.02.014

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Human epidermal growth factor (hEGF) is a monomeric polypeptide consisting of 53 amino acids. The protein acts as an active mitogenic factor and affects cell growth, proliferation and differentiation by specifically binding to its cell surface receptor EGFR. The dysregulation of the hEGF gene is associated with the growth and development of certain cancers. Although hEGF protein shows a quick repair function for epidermal tissue damage and ulceration disease, some ambiguities such as short half-life and EGFR down-regulation still remain. In this study, the human EGF and porcine EGF factor were modified via directed evlotion in vitro by the staggered extension process (StEP), in which a mutant E40V with high affinity against EGFR receptor was obtained using phage display library construction and ELISA screening. Then we used MTT, circular dichroism (CD) and wound healing assay to analyze the A431 and NIH3T3 cell proliferation, migration ability, temperature and pH tolerance of the mutant protein respectively. We found that the affinity of E40V for EGFR was significantly higher than that of wild-type EGF and the mutant could also promote the proliferation of normal cells NIH3T3, while the temperature tolerance and pH tolerance were similar to those of wildtype. Our DNA shuffling EGF with targeting properties and long halflife may provide a new application foreground for regulations of the normal cell growth and cancer targeting therapy.

Synthesis and structural analysis of LDH-CO₃-SO₄-Cl whiskers

WU Jiansong； ZHAO Sina；IN Zhixian；WEI Wenjun

2019, 58(2):  121-127.  doi:10.13471/j.cnki.acta.snus.2019.02.015

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A fine-quality LDH-CO₃-SO₄-Cl whisker was synthesized via liquid precipitation method using MgSO₄·7H₂O and AlCl₃·6H₂O and as raw materials and Na₂CO₃NaHCO₃ buffer solution as precipitant. The influences of buffer solution concentration on the characteristics of the samples were investigated. Whisker samples were characterized by X-ray diffraction, transmission electron microscopy, and Brunauer-Emmett-Teller N₂ surface area measurements. The results showed that the buffer solution concentration in the system had a greater impact on whisker defined shape. The crystal cell parameter LDH-CO₃-SO₄-Cl whisker with well-defined shape, distinct intercalated structure, regular quality, and welldispersing capability could be obtained under the following conditions: buffer solution volume ratio of 40%, reaction temperature of 80 ℃, and reaction time of 148 h. The whisker obtained was well-crystallized and had the morphology of homogeneous and fiber bar.

The regularity criteria to the three-dimensional incompressible Boussinesq equations

GUO Xiangxiang; GUO Congchong

2019, 58(2):  128-134.  doi:10.13471/j.cnki.acta.snus.2019.02.016

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The regularity criteria of the three-dimensional incompressible Boussinesq equations are mainly considered. It is proven that if one component of the velocity field satisfies  ∫^T*₀‖u_i‖^p_Ｈ (1/2+2/p_(R3)ds<∞,p∈(2,∞),i=1,2,3 to the Boussinesq equations, the local solution can be continuously extended to the endpoint. This result improves and develops some known regularity criteria of the threedimensional incompressible Boussinesq equations, which is a supplement to the regularity theory.

Regularized Newton iteration method for an interior inverse scattering problem with a Neumann boundary condition

LIU Lihan； CAI Jingqiu,；CUI Xiaoying

2019, 58(2):  135-141.  doi:10.13471/j.cnki.acta.snus.2019.02.017

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An interior inverse scattering problem with a Neumann boundary condition is studied by using regularized Newton iteration method. First, the conclusion that the position and the shape of a cavity with a Neumann boundary condition can be uniquely determined by providing measurements of point sources inside the cavity is proven. Then, the boundary value problem of the partial differential equation can be transformed into an equivalent system of nonlinear integral equations, and the unknown boundary of the system is solved by the regularized Newton iteration method. Finally, some numerical examples are given to illustrate the effectiveness and feasibility of the method.

Infinitely many solutions of a class of fractional Kirchhoff equation

ZHANG Shengui

2019, 58(2):  142-147.  doi:10.13471/j.cnki.acta.snus.2019.02.018

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Dirichlet boundary value problem for Kirchhoff equation with fractional p(x)-Laplacian operator is studied. When the nonlinear term is growing superlinearly, some sufficient conditions for the existence of infinitely many high energy solutions are obtained by using the fountain theorem in critical point theory.

Elegant conjecture of bicyclic graphs

ZHAO Ke；LI Jingwen；WEI Zhongde；WANG LuLu

2019, 58(2):  148-154.  doi:10.13471/j.cnki.acta.snus.2019.02.019

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A recursive backtracking algorithm is designed by combining pruning with pre-judgment function. All the bicyclic graphs in 16 points are elegantly verified, and all elegant and non-elegant graphs in 16 points are obtained. According to the experimental results, when 4≤p≤16 and p+1=1(mod 4),the bicyclic graphs C_(m,n) is a non-elegant graph, and the number of non-elegant graphs are p/2－2, and all the other bicyclic graphs are elegant graphs. Finally, the conjecture is given: the bicyclic graphs are almost all elegant graphs.

The stability of a SEIR model with saturate incidence and latency

DOU Zhongli；WANG Rui

2019, 58(2):  155-160.  doi:10.13471/j.cnki.acta.snus.2019.02.020

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A SEIR infectious disease model with saturated incidence and latency is studied. The basic number of regeneration that determines extinction or persistence of diseases is determined. The existence of the model‘s equilibrium point is analyzed. Firstly, the global stability of disease-free equilibrium point is proved by constructing the Lyapunov function appropriately. Then, the asymptotic stability of local diseases-equilibrium point is analyzed by using the composite matrix judgment theorem. Finally, the global stability of local diseases-equilibrium point is proved by applying the competition system theorem.