Journal of University of Chinese Academy of Sciences

New project gradient methods for quadratic programming with linear equality constraints

LI Mingqiang, GUO Tiande, HAN Congying

2018, 35 (3): 289-296. DOI: 10.7523/j.issn.2095-6134.2018.03.001

Recently, researchers proposed many accelerated project gradient methods based on new step length choice rules for large scale optimization problems. In this paper, we propose two project gradient methods with variants of new selection rules for quadratic programming with linear equality constraints. One is a non-monotone project gradient method for which an adaptive line search method is adopted and the Barzilai-Borwein step size is applied, and the other is a monotoneproject gradient method with Yuan step size. We give the global convergence of these two methods under mild assumptions. Numerical experiments indicate that both the new methods are more efficient than traditional project gradient methods.

Half-metallicity of monolayer transition metal halide zirconium trichloride

HUANG Qiang, HUANG Yizhen, ZHENG Qingrong, SU Gang

2018, 35 (3): 297-301. DOI: 10.7523/j.issn.2095-6134.2018.03.002

Abstract ( 367 ) PDF (KB) ( 0 )

Many new monolayer materials were synthesized in past years, and seeking new types of 2D materials is interesting. In this paper, by means of the first-principle calculations we find that monolayer zirconium trichloride(ZrCl₃) is a half-metal, which could be potentially applied in spintronics. We systematically study the geometric, electronic, and magnetic properties of ZrCl₃ monolayer. The phonon spectra indicate that it is kinetically stable. In the electronic structure, we observe that minority states of electrons are gapped at the Fermi level while the majority states are not, suggesting that ZrCl₃ monolayer is a half-metal. We uncover that the ferromagnetic state is energetically stable. The magnetic moment of Zr atom in ZrCl₃ monolayer is one Bohr magneton. The exchange constant is estimated to be 7.58meV. By using Monte Carlo method, the Curie temperature is calculated to be about 130K.

Spin-polarized transport through a device of single-ion magnet C₁₈H₂₃Er

ZHOU Jie, WANG Zhengchuan

2018, 35 (3): 302-307. DOI: 10.7523/j.issn.2095-6134.2018.03.003

Abstract ( 269 ) PDF (KB) ( 7 )

We study the spin-polarized transport through devices of single molecule magnet. A device consisting of the scanning tunneling microscopy Co tip, the single-ion magnet of erbium, and the Au(111) substrate is set up. We calculate the spin-polarized I-V curves for the upward and downward structures of single-ion magnet at a small bias, and find that the tunnel magnetoresistance is as high as 120% and the efficiency of the spin filter at small bias is between 70%-100%. By comparing the spin rectification ratios of the two structures, we find that the downward structure has better spin rectifying effect. Based on the analyses of the transmission spectrum, the molecular projection Hamiltonian, and the projection device density of states, we give reasonable explainations for the above observations.

Four-way catalytic performance of MgAlO doped by K

ZHANG Junwu, YANG Li, ZHANG Yuxiu, SHU Xinqian, DENG Zengshe

2018, 35 (3): 308-313. DOI: 10.7523/j.issn.2095-6134.2018.03.004

Abstract ( 234 ) PDF (KB) ( 15 )

A series of K-MgAlO catalysts were synthesized by coprecipitation and impregnation methods. The K-MgAlO catalysts were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and Fourier transform infrared (FT-IR) spectroscopy. The catalytic activity of K-MgAlO for simulation diesel engine exhaust gas was tested by the temperature programmed. The results showed that K existed on the surface of MgAlO in highly dispersed form when it is doped by 7%. The conversion rates of NO, CO, and C₃H₆ using the K-MgAlO catalyst reached 80% at the temperatures of 343, 335, and 298℃, respectively. The ignition temperature of soot was reduced from 380 to 253℃. All the results indicate that the four-way catalytic effect of MgAlO doped by K is stronger than that of the MgAlO catalyst.

Regulating depletion interaction between micelle and selective substrate

ZHOU Jingyu, ZHANG Xinghua, MIAO Bing

2018, 35 (3): 314-319. DOI: 10.7523/j.issn.2095-6134.2018.03.005

Abstract ( 251 ) PDF (KB) ( 0 )

In this paper, self-consistent field theory is used to study the depletion interaction between spherical micelles and planar substrate induced by polymer solvents. In this system, diblock copolymers form micelles and homopolymer solvents act as depletion initiators. When the spherical micelle approaches the planar substrate, the depletion interaction will allow the micelle to be adsorbed near the substrate. The structure between the substrate and the bulk is controlled through adjusting the amplitude of the attractive interaction of the substrate, which results in the regulation of the depletion interaction.

Research on bioaerosol and its climate effects

WEI Wenfei, LIU Lichao, CHEN Bin, TAN Saichun, SHI Guangyu, XIE Min

2018, 35 (3): 320-326. DOI: 10.7523/j.issn.2095-6134.2018.03.006

Abstract ( 365 ) PDF (KB) ( 1 )

In this article we overviewed the history and trend of the research on bioaerosol and briefly summarized its direct and indirect climatic effects, focusing upon the influence of bioaerosal, as atmospheric ice nuclei (IN) and cloud condensation nuclei (CCN), on cloud and precipitation formation. We suggest to increase the model and simulation studies and improve the observation technologies and analysis methods.

Retrieval of soil moisture in Zhangye Prefecture based on Radarsat-2 data

WANG Ruixin, SONG Xiaoning, MA Jianwei, SUN Chuan

2018, 35 (3): 327-335. DOI: 10.7523/j.issn.2095-6134.2018.03.007

Abstract ( 195 ) PDF (KB) ( 0 )

Soil moisture is an important parameter in hydrology, agriculture, ecology, and many other research fields. A simplified model for the retrieval of soil moisture is established in the paper. The simplified model improves inversion accuracy by incorparating the characteristics of qual polarization radar data and eliminates roughness in model. The results show that VV/HH, VV/VH, and HH/HV can be used in the inversion of soil moisture in the bare soil region and the VV/VH polarization combination performs the best. In this paper we use Radarsat-2 data to retrieve the soil moisture in bare soil and plant areas in the middle basin of Heihe River and use field survey data to verify the results. The results show that the VV/VH polarization combination inversion results are in good agreement with the field survey results and the RMSE values in the bare and plant areas are 0.006 and 0.017cm³·cm^-3, respectively. The VV/VH polarization can be used to invert the soil water content in the bare soil region. This work has laid a foundation for quick and accurate acquirement of the regional soil moisture.

Interactive rules between producer services and manufacturing industries in Beijing based on input-output model

WANG Hongjie, BAO Chao, GUO Jiaying

2018, 35 (3): 336-344. DOI: 10.7523/j.issn.2095-6134.2018.03.008

Abstract ( 229 ) PDF (KB) ( 30 )

The input-output model was used to analyze the interactive rules between producer services and manufacturing industries in Beijing. Results are showed as follows. 1) The manufacturing industry reduced the intermediate demand for transportation,while increased the intermediate demand for scientific research and information service from 2002 to 2012. 2) More than 40% of intermediate inputs that producer services gave to manufacturing industries concentrated on technology-intensive industries. However, the intermediate inputs of different producer services had their own emphases. 3) The forward and backward association effects of manufacturing industries were both strong but had declining trends. However, the producer services mainly showed forward association effect. In order to promote the integration of producer services and manufacturing industries, transportation and warehousing industry should be improved right along; scientific research and comprehensive technical services, information transmission, computer services, and software industry should be promoted vigorously and used widely; and intermediate input to technology-intensive manufacturing industries should be improved continuously.

Vulnerability of social-ecosystem in agro-pastoral ecotone in western Northeast China

WANG Linfeng, ZHANG Pingyu, LI He, LIU Shiwei

2018, 35 (3): 345-352. DOI: 10.7523/j.issn.2095-6134.2018.03.009

Abstract ( 242 ) PDF (KB) ( 0 )

The vulnerability study has become a powerful tool for the comprehensive analysis of the social-ecosystem. This paper analyses the spatio-temporal characteristics of vulnerability of the social-ecosystem in the agro-pastoral ecotone in western Northeast China by constructing a vulnerability evaluation index system. The results are given as follows. 1) The vulnerability level in the agro-pastoral ecotone in western Northeast China totally demonstrated a downward trend from 2005 to 2015, and it evolved from 1.343 in 2005 to 1.197 in 2015. 2) The vulnerability in the southwest of the study area is at high level while in the northeast it is relatively low. Additionally, it stays stable in the north while declines in the south and in the central region. 3) The low response ability is the main characteristic in the agro-pastoral ecotone and the various vulnerable types demonstrate differential distributions. Under the background of the current grain structure adjustment in Northeast China, it is an effective way to ensure the sustainable development of the region to implement different strategies according to the different characteristics.

High efficient 2D/3D point inclusion test approach based on point circle theory

WEI Yansheng, ZHANG Shuqing, LI Huapeng, DING Xiaohui, LIU Zhao

2018, 35 (3): 353-361. DOI: 10.7523/j.issn.2095-6134.2018.03.010

Abstract ( 239 ) PDF (KB) ( 0 )

According to the problem that 2D/3D point inclusion test approach is complex and low-efficient, we propose a new method based on point circle theory. Projections of different types of singular points and their overlay properties on point circle are geometrically analyzed, and their determinations are proposed. 3D point inclusion test is transformed to 2D point inclusion test, except for the calculation of the plane equation coefficients. Based on the filter and accumulation of edges intersecting with and lying above or below the ray shooting from the test point, the point inclusion can be determined according to the odd/even property of the edges. Common geometric characteristics of the consecutive edges of a polygon lying above or below the 2D ray are recognized, i.e., their y-coordinate values either collectively larger or smaller than that of the test point. A high efficient 2D point inclusion algorithm named increment filter crossing number (IFCN) method is thus established. The experiment results show that the proposed 2D/3D point inclusion algorithms are highly reliable and efficient. They are capable of treating any singularities and suitable for any polyhedrons (manifold, non-manifold, planar-faced or curved-faced surface, etc.) or any polygons.

Stability evolutionary tendency of basin economic system of Songhua River in Jilin Province

SUN Yongsheng, TONG Lianjun

2018, 35 (3): 362-369. DOI: 10.7523/j.issn.2095-6134.2018.03.011

Abstract ( 170 ) PDF (KB) ( 0 )

Based on the knowledge and understanding of stability, this paper establishes an evaluation index system and an evaluation model of stability of basin economic system from the aspects of stability elements such as pressure, sensitivity, and system response, and analyzes the stability evolution characteristics of basin economic system of Songhua River in Jilin province. The results are given as follows. Firstly, the pressure of basin economic system of Songhua River in Jilin Province has obvious spatial differentiation characteristics. Secondly, the internal structures and functions of economic systems in Jilin city, Songyuan city, and Baicheng city are not reasonable, which implies low level of economic structure of the Songhua River basin in Jilin Province. Thirdly, the response of basin economic system of Songhua River in Jilin Province shows a feature of gradually decreasing from upstream to downstream. Finally, the stability of basin economic system of Songhua River in Jilin Province shows a center-periphery feature, and the differences between the regions are constantly expanding, especially the difference between Changchun city and Baicheng city. It will be very important for the process of economic development in future to consolidate the dominant position of the core cities in the basin, accelerate the economic development of the marginal cities in the basin, pay attention to the quality and efficiency of economic development, and avoid further widening the gap.

Variations in temperature and precipitation and their influences on surface water resource in different climate zones of Xinjiang

LI Jiaxiu, CHEN Yaning, LIU Zhihui

2018, 35 (3): 370-381. DOI: 10.7523/j.issn.2095-6134.2018.03.012

Abstract ( 288 ) PDF (KB) ( 0 )

In this paper we use Mann-Kendall test method, canonical correlation analysis, and stepwise regression analysis methods to study temperature and precipitation variations in different climate zones of Xinjiang and study influence factors on surface water resource. The results are shown as follows. 1)Temperature and precipitation increase at the rates of 0.32℃/10a and 8mm/10a, respectively. Temperature increase is more significant and it is mainly contributed by the lowest-temperature increase. 2)Temperature rises faster after 1987 than before, while precipitation shows a weak downward trend before 1987 and a weak upward trend after 1987. 3)The increase rates of both temperature and precipitation gradually decrease from north to south, and the northern Xinjiang becomes more warm and wet. 4)The surface water resources of the southern slop of Altai Mountains and the northern slop of Tianshan Mountains are mainly dominated by the hydrological years precipitation change, while the resources of the southern slop of Tianshan Mountains and the northern slop of Kunlun Mountains are mainly dominated by the temperature change during the period from May to September.

Spatio-temporal evolution characteristics of health resources mismatch in Urumqi-Changji region

CHENG Lanhua, YANG Degang

2018, 35 (3): 382-390. DOI: 10.7523/j.issn.2095-6134.2018.03.013

Abstract ( 184 ) PDF (KB) ( 0 )

From the perspective of mismatch,this paper introduces the knowledge about the mismatch of health resources and uses healthy distance model in the ecology to study spatial-temporal evolution characteristics and mechanism of the mismatch of health resources in Urumqi-Changji region from 2005 to 2014 in order to make use of health resources and promote the development of Urumqi-Changji integration effectively. It is found that the mismatch degree of health resources is declining and has obvious characteristics of periodic and regional differences from 2005 to 2014. The mismatch degree can be divided into high mismatch dominated stage (2005-2006), smooth descent stage (2007-2009), and volatile descent stage (2010-2014). The differences in mismatch degree among the regions are expending during this period. The spatial pattern evolution of the mismatch has obvious directional and structural features, showing a trend from high mismatch to adaptation, and the structure evolution shows a trend from V-shaped pattern to M-shaped pattern. Local economic and social foundation (internal factors), local government fiscal spending and administrative ability (direct factors), and the national health policies and macro regional development strategies (external factors) influence each other and jointly promote the spatial-temporal evolution of health resources mismatch in Urumqi-Changji region.

An improved LDR image enhancement algorithm based on visual characteristics and gray scale compensation

HE Baochang, GENG Xiurui, HU Wenlong

2018, 35 (3): 391-401. DOI: 10.7523/j.issn.2095-6134.2018.03.014

Abstract ( 296 ) PDF (KB) ( 0 )

In view of the drawbacks of traditional spatial image enhancement algorithms, this paper proposes an improved algorithm based on the layered difference representation (LDR) algorithm which constructs a two-dimensional histogram containing the spatial context information. The histogram exploits the visual characteristics to construct a two-dimensional visual difference histogram, which is consequently used in the enhancement of the input images with LDR. Finally, the grayscale compensation method is used to ameliorate the over-enhancement problem. Experimental results show that the proposed algorithm produces better visual effects (performance), improves the overall brightness and contrast, and eliminates the artifacts. The proposed method is free of parameter selection and meets the real-time processing requirement.

Recognition of overlaid Chinese characters in videos without binarization

TIAN Jie, WANG Weiqiang, SUN Yi

2018, 35 (3): 402-408. DOI: 10.7523/j.issn.2095-6134.2018.03.015

Abstract ( 241 ) PDF (KB) ( 12 )

In this paper, a new method for recognizing caption texts in videos is proposed. Due to varying font sizes, colors, styles, and resolutions and complex backgrounds in videos, it is still a challenging problem to recognize overlaid texts in videos. Most existing overlaid text recognition methods are based on the combination of text binarization and traditional OCR engine. However, the process of text binarization may incur noises and text stroke information loss. Additionally, techniques of traditional OCRs are mainly focused on high-resolution scans of printed documents, which have the characteristics of single color background, little noise, and more complete stroke information. Hence, traditional OCR engines might not be robust enough to recognize the binarization results of overlaid text images. In order to solve this problem, we directly extract Gabor features from overlaid text images without binarization for training the two-level character recognizer. The final experimental results demonstrate that the proposed method makes a great progress in overlaid Chinese text recognition with multiple fonts.

An automated and directed testing technique for target behavior of Android application

YE Yanling, FU Xiaotong, ZHANG Yuqing, YUE Hongzhou

2018, 35 (3): 409-416. DOI: 10.7523/j.issn.2095-6134.2018.03.016

Abstract ( 208 ) PDF (KB) ( 0 )

Directed testing of specific behaviors for Android applications is usually used to detect privacy leak, remote control, or other malicious behaviors. In order to solve the problems of the high failure-rate and large time-consuming of the present approaches, an automated testing method that uses target API invocation to represent the application's behavior is proposed. First, the method gets the invocation paths to the target API by using static analysis. Then dynamic testing is adopted to exclude extraneous components and GUI elements, and the application is driven to automatically run along the specific paths to reach the target API invocations and the specific behavior is triggered. Experimental results show that the method achieves a high efficiency.

Effects of nitrogen and phosphorus application on soil microbial biomass carbon and nitrogen contents on an alpine grassland on Tibetan Plateau

ZHAO Guoqiang, WANG Shuping, CUI Xiaoyong, DONG Junfu, CHANG Xuhui, WANG Shiping

2018, 35 (3): 417-424. DOI: 10.7523/j.issn.2095-6134.2018.03.017

Abstract ( 267 ) PDF (KB) ( 12 )

Soil microbes play an important role in maintaining and improving plant productivity as well as soil quality. Based on a two-year field experiment of fertilizer application to an alpine steppe on the Tibetan Plateau, effects of nitrogen and phosphorus addition on soil microbial biomass carbon (MBC) and nitrogen (MBN) contents in the upper 30cm soil were studied. The results are given as follows. 1) Nitrogen and phosphate addition influenced soil MBC content mainly in the 0-10cm soil layer, and the content was 1.67 times and 1.28 times the contents in the 10-20cm and 20-30cm soil layers, respectively. 2) Sole nitrogen addition significantly decreased soil MBC and MBN contents, whereas nitrogen application in addition to phosphorus fertilization increased soil MBC and MBN contents. 3) Phosphorus fertilization alone had no significant effect on soil MBC and MBN contents. Combined with nitrogen fertilizer at the N₂ level of 15g N/m², phosphorus application at the levels of 15 and 30g P₂O₅/m² (i.e., P₂ and P₃ levels) significantly increased MBC content in the 0-10cm soil layer and MBN content in the 10-20cm soil layer, as compared with control treatment. Furthermore, MBN content in the 10-20cm soil layer was also significantly higher in the N₂P₁ (15g N/m² and 7.5g P₂O₅/m²) treatment than CK treatment.

Region-of-interest based error resilient scheme for HEVC conversational video transmission

HE Zhitao, ZHANG Can, CHEN Deyuan

2018, 35 (3): 425-431. DOI: 10.7523/j.issn.2095-6134.2018.03.018

Abstract ( 213 ) PDF (KB) ( 0 )

Conversational video coding and transmission on resource-constrained mobile phones has been a key technology. We propose a novel error resilient scheme for conversational video transmission in HEVC which is based on the fast extraction for region-of-interest (ROI) according to skin color, motion, and texture information and adjustments for the ROI weights using the packet-loss rate. The simulation results show that, compared to the random frame refresh method, the proposed scheme improves PSNR of the ROI by at least 0.7dB and reduces coding time by 20%-40% when the video coding and delivery is over the channel with the packet-loss rate of 5%-20%. At the same time the actual bitrate matches the target bitrate.

Current Issue