最新刊期
卷 58 ， 期 2 ， 2019
- 摘要：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.关键词：multivariate time series;similarity;dynamic time warping;Mahalanobis distance;information entropy
- 304
- |
- 290
- |
- 3
发布时间：2023-12-11 - 摘要：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.关键词：deep convolution neural network;heat map;adaptive supervision;scene classification
- 236
- |
- 191
- |
- 0
发布时间：2023-12-11 - 摘要：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.关键词：subway platform fire;numerical simulation;evacuation strategy;smoke spread
- 271
- |
- 396
- |
- 1
发布时间：2023-12-11 - 摘要：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.关键词：coupled resonant wireless power transfer;AC-AC converter;PFC
- 150
- |
- 141
- |
- 0
发布时间：2023-12-11 - 摘要：The effect of different diluents on the NOxemission of the combustion of natural gas with CO2and N2was studied with premixed methane/air/diluent flame. The chemical effect and thermal effect of CO2on the NO production was revealed via conducting reactionpath analysis. The numerical results show that: 1) CO2is 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 NOxemission characteristic of diluents accompanies with significant inhibiting effect on the combustion of the mixture.关键词：natural gas;NOx;diluent;Kinetic reaction mechanism
- 147
- |
- 294
- |
- 0
发布时间：2023-12-11 - 摘要：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 singlevehicle 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.关键词：mesoscopic traffic flow model;parameter calibration;single-vehicle speed distribution;K-S statistics
- 178
- |
- 146
- |
- 0
发布时间：2023-12-11 - 摘要：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 postforming experience and the remaining time of diamonds on earths 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 H2Orich 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 contentbased 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.关键词：diamond;modern river placer;morphology;provenance and origin;Hunan
- 219
- |
- 160
- |
- 4
发布时间：2023-12-11 - 关键词：aerosol optical depth(AOD);angstrom parameter;aerosol size distribution;Guangzhou
- 230
- |
- 162
- |
- 0
发布时间：2023-12-11 - 摘要：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 “SouthJiangsu 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 profitseeking tendency of financial capital further expands the differences in urban power in the network.关键词：financial enterprise network;power space;space-production;urban agglomeration;the Yangtze River Delta
- 160
- |
- 117
- |
- 0
发布时间：2023-12-11 - 摘要：The growth pattern and distribution characteristics of population in Shenzhen are analyzed using the statistical yearbook and the data from the 3rd to 6th 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.关键词：population growth;population distribution;spatial-temporal change;population variation model;rapid immigration city;Shenzhen
- 233
- |
- 201
- |
- 1
发布时间：2023-12-11 - 摘要：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, spatialtemporal distribution of the frequency, countytimes 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.关键词：the Jin-Shan-Inner Mongolia adjacent area;freezing disaster;spatial-temporal distribution
- 190
- |
- 133
- |
- 0
发布时间：2023-12-11 - 摘要：To study the polyphenols fromDendrobium loddigesiiand their biological activities, the 80% acetone extract fromD. loddigesiiwas isolated and purified by chromatography techniques; the structures of obtained compounds were identified with spectroscopic techniques; the antioxidative, α-glucosidase inhibitory and antiinflammatory activities of compounds were evaluated. Fifteen compounds were isolated and identified as chrysotoxol A (1), neoechinulin A (2), 3,6,9trihydroxy-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-9,10dihydrophenanthrene (12), loddigesiinol B (13), loddigesiinol I (14), loddigesiinol J (15),respectively. Compounds1-11among them were isolated fromD. loddigesiifor the first time. The biological activities of compounds1-4, 6, 7and12were evaluated for the first time under trial conditions. It was reported for the first time that compounds1, 3and12had a strong antioxidant activity, compounds1and9showed a strong α-glucosidase inhibitory activity, and compounds1,12, 14and 15 had a strong anti-inflammatory activity.
- 192
- |
- 132
- |
- 2
发布时间：2023-12-11 - 摘要：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.关键词：lignin modification;demethylation;crosslinking;freeze-drying;rhodamine B;dye adsorption
- 233
- |
- 156
- |
- 4
发布时间：2023-12-11 - 摘要：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 wildtype. Our DNA shuffling EGF with targeting properties and long halflife may provide a new application foreground for regulations of the normal cell growth and cancer targeting therapy.关键词：epidermal growth factor;directed evolution;phage display library;circular dichroism
- 299
- |
- 137
- |
- 0
发布时间：2023-12-11 - 摘要：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 Na2CO3NaHCO3buffer 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 N2surface 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 welldispersing 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.关键词：LDH-CO3-SO4-Cl whisker;synthesis;structural analysis
- 180
- |
- 146
- |
- 0
发布时间：2023-12-11 - 摘要：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‖ui‖pＨ(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 threedimensional incompressible Boussinesq equations, which is a supplement to the regularity theory.关键词：the three-dimensional incompressible Boussinesq equations;one component of the velocity field;regularity criteria
- 239
- |
- 158
- |
- 0
发布时间：2023-12-11 - 摘要：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.
- 191
- |
- 150
- |
- 2
发布时间：2023-12-11 - 摘要：Dirichlet boundary value problem for Kirchhoff equation with fractionalp(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.关键词：Kirchhoff equation;fractional differential equation;p(x)-Laplacian operator;superlinear;critical point
- 194
- |
- 191
- |
- 0
发布时间：2023-12-11 - 摘要：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 andp+1=1(mod 4),the bicyclic graphsC(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.关键词：bicyclic graphs;elegant graphs;elegant labeling;elegant conjecture of bicyclic graphs
- 157
- |
- 130
- |
- 0
发布时间：2023-12-11 - 摘要：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.关键词：reproduction number;stability;composite matrix;competitive system
- 214
- |
- 167
- |
- 0
发布时间：2023-12-11
- Postal code：510275
- Tel：020-84112585，84113223 Email：xuebaozr@mail.sysu.edu.cn
- Technical support is provided by Beijing Founder electronics co., LTD 京ICP备09064830号-19
京公网安备11010802024621 - It is recommended to read the content of this site in Chrome&IE9+. Please switch to extreme mode in browser 360.
- Cookies We use cookies to help provide and enhance our service and tailor content. By continuing, you agree to the use of cookies.
0