Journal of University of Chinese Academy of Sciences

First-principles study on electronic structures of doped graphdiynes

ZHANG Zihan, CUI Huijuan, YAN Qingbo, SU Gang

2019, 36 (6): 721-728. DOI: 10.7523/j.issn.2095-6134.2019.06.001

Graphdiyne is a new type of two-dimensional carbon material successfully synthesized in recent years. It has a peculiar structure, rich hybrid bonds, and interesting electronic properties, and has a wide range of potential applications. We perform the first-principles calculations based on density functional theory to study the silicon, germanium, boron, nitrogen, and phosphorus doped graphdiynes and boron-nitrogen and boron-phosphorus co-doped graphdiynes systematically. Our results show that Si and Ge doped graphdiynes and B-N and B-P co-doped graphdiynes are semiconductors with band gaps from 0.004 to 0.49 eV, and B, N, and P doped graphdiynes all become conductors. The present study on the band structures of doped graphdiynes helps to engineer the band gap of graphdiyne and manipulate Fermi level of graphdiyne.

Exclusive quarkonium production in high energy e-p collision

WANG Chen, CHEN Ziqiang, QIAO Congfeng

2019, 36 (6): 729-735. DOI: 10.7523/j.issn.2095-6134.2019.06.002

Abstract ( 403 ) PDF (KB) ( 6 )

Quarkonium production and decay play an important role in the investigations of quantum chromodynamics(QCD) and the properties of quarkonium and other high energy interactions and particles. In this work, we calculate the heavy quarkonium exclusive production in electron-proton scattering, and find that it may deepen our understanding of the parton structure of nucleon, testify the non-relativistic QCD(NRQCD) formalism, and specify the applicability scope of perturbative QCD(pQCD). Within the collinear factorization framework, we analytically calculate the amplitude and cross section of quarkonium exclusive production at the leading order of pQCD. Taking the HERA experiment of photoproduction and electroproduction as an example, we analyze phenomenologically the cross-section dependence of J/ψ and Υ production on Q² and W_γp. We estimate also the theoretical errors induced by the energy-scale and quark-mass uncertainties.

Numerical study of the relationship between heat flux and drag in the flow on wavy rough-wall

LI Yuchuan, BAO Lin

2019, 36 (6): 736-744. DOI: 10.7523/j.issn.2095-6134.2019.06.003

Abstract ( 267 ) PDF (KB) ( 3 )

This study focuses on the flow and heat transfer characteristics of high-speed airflow over the rough-wall which has periodic roughness and small amplitude. By using the OpenFOAM program, flows on the semi-infinite sinusoidal wavy plates under different inflow conditions are numerically studied. The results show that there is a direct correlation between the wall heat flux coefficient C_Q and the total drag coefficient C_D. For the attached flow, C_Q/C_D only depends on the equivalent roughness h, which is the ratio of the roughness to the thickness of the boundary layer. When the flow separation occurs, C_Q/C_D no longer changes with roughness and only depends on the position variable x, which is defined by the similar transformation.

Time matrix product state: theory and applications

PENG Cheng, RAN Shiju

2019, 36 (6): 745-751. DOI: 10.7523/j.issn.2095-6134.2019.06.004

Abstract ( 415 ) PDF (KB) ( 3 )

In this work, we propose an efficient approach to identify the criticality of finite-size quantum systems in higher-dimensions. Starting from the analysis of the numerical renormalization group flows, we build a general equivalence between the higher-dimensional ground state and an one-dimensional (1D) quantum state defined in the imaginary time direction in terms of the so-called time matrix product state (tMPS). We show that the criticality of the targeted model can be identified by the tMPS. We benchmark our proposal with the results obtained from the spin-1/2 Heisenberg antiferromagnet on honeycomb lattice. We also demonstrate critical scaling behavior of the tMPS on the spin-1/2 kagome Heisenberg antiferromagnet. The present study indicates that the 1D conformal field theory in the imaginary time provides a useful tool to characterize the criticality of higher-dimensional quantum systems.

Applications of water-soluble AgBiS₂ nanoparticles in photothermal/radiotherapy and in vivo imaging

CHEN Yiwei, PENG Aidong

2019, 36 (6): 752-759. DOI: 10.7523/j.issn.2095-6134.2019.06.005

Abstract ( 385 ) PDF (KB) ( 5 )

Noble metal and high Z number nanomaterials are[JP+1]both popular stuff in the bioinorganic materials field, while the biomedical application of ternary sulfides AgBiS₂ nanomaterial containing the two nanomaterials is reported for the first time. We synthesized a water-soluble AgBiS₂ nanoparticle with PEG modification, and carried out a set of in vitro, intracellular, and mice imaging experiments that revealed its low cytotoxicity, photothermal lethality toward cancer cells, ability to cause DNA lesions by generating ROS under X-ray radiation which suppresses the reproduction of cancer cells, and good performance as photoacoustic and CT contrast agent.

An examination of the use of “gradient” in ecology in China

CUI Xiaoyong, YANG Yining

2019, 36 (6): 760-765. DOI: 10.7523/j.issn.2095-6134.2019.06.006

Abstract ( 302 ) PDF (KB) ( 3 )

The rapid development of ecology in China has introduced new terms or new meanings into the existing terms, which may cause confusion in communication due to ambiguity of these terms. Taking the word "gradient" as an example, we investigate its usages in English dictionaries and the ecological literature, analyze differences in meaning between ecology and other disciplines, and trace back the introduction and expansion of this word in the Chinese ecological literature. We find that the word "gradient" has been misused extensively in Chinese ecological publications. The use of a single term to express two different meanings in translation may be responsible for the wide misuse. Non-uniqueness of Chinese characters exaggerates the situation. We propose a solution and call for attention to other scientific terms.

Spatial pattern characteristics of traffic accessibility of districts and urban and rural areas in Tanzania

ZHANG Jiaqi, CHEN Shuang, GAO Qun, ISMAEL A. Kimirei

2019, 36 (6): 766-773. DOI: 10.7523/j.issn.2095-6134.2019.06.007

Abstract ( 309 ) PDF (KB) ( 2 )

Tanzania is an important gateway of "the Belt and Road Initiative" into Africa and the continent, and it faces the serious shortage of transport infrastructure in the rapid urbanization process. Based on the spatial data of roads, railways, airports, ports, cities, and population, GIS spatial analysis technology and traffic accessibility index model were employed to study the spatial pattern of traffic accessibility of districts and of urban and rural areas in Tanzania. The findings are shown as follows. 1)The traffic accessibility of districts in Tanzania was extremely uneven. The high value area was mainly located along the northeast coast and the coast of Vitoria Lake, while the low value area was mainly located in the middle north region of the central railway line and in the south of the central railway line. 2) Due to the factors such as geographical location, resource endowment, colonial history, and government policy, there was a significant difference in traffic accessibility between urban and rural areas. The results are helpful for Tanzania to formulate regional traffic development policies and optimize the allocation of resources. The results have certain significance for promoting the accurate industrial docking and capacity transfer between China and Tanzania.

Temporal and spatial pattern evolution and influencing factors of urbanization at county level in Xinjiang

LI Jian'gang, LEI Jun, DUAN Zuliang, YANG Zhen

2019, 36 (6): 774-783. DOI: 10.7523/j.issn.2095-6134.2019.06.008

Abstract ( 399 ) PDF (KB) ( 3 )

The temporal and spatial pattern evolution characteristics and the influencing factors of urbanization at county level in Xinjiang since 2000 were analyzed using the methods including variation coefficient, multivariate regression, and geographical detector technique. The main conclusions are given as follows. 1) The urbanization rate in Xinjiang's counties continually increased with an average annual growth rate of 0.89%, and 40.96% of the counties had average annual growth rates of 0-0.5%. 2) There was a great change in the spatial distribution pattern of county urbanization, and that was the change from the planar distribution pattern of the initial urbanization stage in 2000 into the centralized-interlaced distribution pattern of the initial and middle urbanization stages in 2015. 3) The economic development level, employment structure, public service level, and geographical location have significant impacts on the spatial differentiation of urbanization. The development of market economy and the transformation of employment structure were important factors driving the rapid development of urbanization. The driving force for urbanization development from the government-led top-down policies and measures decreased gradually. At the present, urbanization development is mainly affected by multiple factors such as employment ability, income level, population concentration, and public basic services.

Water body emissivity measurement in Taihu Lake and its application in the watersurface temperature retrieval using the MODIS datasets

YAN Fuli, LIN Yasen, WANG Shixin, ZHOU Yi

2019, 36 (6): 784-793. DOI: 10.7523/j.issn.2095-6134.2019.06.009

Abstract ( 384 ) PDF (KB) ( 3 )

Emissivity of the surface target is an important parameter for remote sensing surface temperature retrieval, and the changes of water constituents bring about changes of water physical property and influence emissivity. However, studies on influences of water body constituent on emissivity are rare at the present. In this study, we determined the influences of blue-green algae and suspended sediments on water body emissivity using the Nicolet iS50 FT-IR spectrometer of Thermos Scientific Co. Ltd with an integrating sphere of the PIKE technologies, and proposed a method to obtain case II water emissivity. Based on the classic split window method and the MODIS datasets, we compared the water surface temperature retrieved using the proposed emissivity with the temperature retrieved using the widely-used water emissivity. Analysis indicates that blue-green algae and suspend solid do have influences on water body emissivity, and suspend solid has greater influence. The maximum influence on surface temperature retrieval is 1.21℃ when we take blue-green algae and suspend solid into a comprehensive consideration. The maximum influence of blue-green algae is 0.86℃ when suspend solid concentration is low. The maximum influence of suspend solid is 0.98℃ when blue-green algae concentration is low. In the actual retrieval and authenticity test, the concentrations of blue-green algae and suspended solid are low, the overall maximum influence on surface temperature retrieval is 0.78℃, and the impacts at most of the validation samples are between 0.53℃ and 0.78℃. Experiment shows that the introduction of emissivity correction function based on the chlorophyll-a concentrations of the blue-green algae and suspended sediments considerably reduces errors in water surface temperature retrieval.

Comparative study on water extraction methods based on Sentinel-1/2: a case study of small water body in Sri Lanka

ZHOU Han, YE Huping, WEI Xianhu, ZHANG Zongke, WANG Fali, QI Yongju, MA Jianru

2019, 36 (6): 794-802. DOI: 10.7523/j.issn.2095-6134.2019.06.010

Abstract ( 433 ) PDF (KB) ( 3 )

The accurate extraction of surface water is an important basis for studying the changes of quality and quantity for surface water. Sri Lanka is one of the most important participating countries along "21st-Century Maritime Silk Road".Rainfall is abundant in Sri Lanka. However, due to uneven spatial and temporal distributions of the rainfall, people in Sri Lanka have a long-term difficulty in using water. Study on surface water is helpful for solving the problem of people's livelihood in Sri Lanka. There are a large number of small reservoirs and ponds scattered throughout the country,but it is difficult to extract small area water which is affected by surrounding environment. In this paper, the accuracies and existing problems of water extraction methods, such as single-band method, water body index method, and supervised classification method, were compared and analyzed based on Sentinel 1/2 satellite image in July 2017 in eastern Sri Lanka. The analysis results show that the normalized difference water index (NDWI) method has the highest accuracy with a classification accuracy of 94%.

Remote sensing observation and analysis of seabed villages ruins in Dongzhai Port in Hainan Island

LI Zhixin, WANG Xinyuan, LIU Chuansheng, LUO Lei

2019, 36 (6): 803-809. DOI: 10.7523/j.issn.2095-6134.2019.06.011

Abstract ( 272 ) PDF (KB) ( 3 )

The spatial distribution, present status, and evolution rules of seabed villages ruins in Hainan Dongzhai Port were studied based on space archaeology by using high-precision UAV (unmanned aerial vehicles) orthophoto images, digital elevation model (DEM), Landsat8 images, and field surveys. The results are showed as follows. Firstly, the seabed villages ruins are evenly distributed on both sides of the ancient channel of Dongzhai River. Secondly, some of the seabed villages ruins sink below the sea surface, and some of them are partially exposed after the tide ebbs because these ruins are located in the forefront area of the land-sea interaction, where the geological conditions are unstable. Thirdly, the seabed villages ruins near Linshi Village will continue to sink due to the influence of the earthquake events. The middle part of the ruins have been washed away by the tidal fluctuations, and that part covers an area of about 1 871.5 m² which accounts for 31.5% of the total area of the ruins. Overall, this study is important for the seabed villages ruins protection in Dongzhai Port and also has significance for the development of the Maritime Silk Road.

Study on metallogenic thermodynamic parameters of Lanjiagou molybdenum deposit

GUO Yang, LIU Lidong, CHU Shaoxiong, LI Yongbing, YAN Quanren, SHI Yaolin

2019, 36 (6): 810-816. DOI: 10.7523/j.issn.2095-6134.2019.06.012

Abstract ( 304 ) PDF (KB) ( 3 )

The thermodynamic parameters of ore-forming process are the important content of the genesis of the deposits, and the paragenetic minerals inevitably show the metallogenic thermodynamic environment during their formation. Based on this, the mineral assemblages at different metallogenic stages in Lanjiagou molybdenum deposit are evaluated and three mineralization stages are determined. Then the ore-forming temperatures and pressure ranges of the three mineralization stages are obtained by measuring the temperatures of the inclusions, the phase diagrams of the paragenetic compositional minerals at the different mineralization stages are calculated, and the metallogenic thermodynamic parameters of the three metallogenic stages in Lanjiagou molybdenum deposit are estimated. At the stage of quartz phenocryst, the oxygen fugacity ranged from 10^-40 to 10^-25, while the sulfur fugacity ranged from 10^-40 to 10^-5. At the porphyry mineralization stage, the pH value of the ore deposits was about 6.9-6.1, the oxidation-reduction potential was between -1.3 and 0.3 V. At the quartz large vein mineralization stage, the oxygen fugacity was less than 10^-13, the sulfur fugacity ranged from 10^-14 to 10^-6, and the ore deposit was in a weakly reducing environment. All these results help to understand the metallogenic environment of Lanjiagou molybdenum deposit.

A new approach for spatial-temporal multidimensional visualization of ionospheric electron density data based on virtual earth

GUO Changshun, FAN Xiangtao, TAN Jian, ZHAN Qin, KANG Xujie

2019, 36 (6): 817-824. DOI: 10.7523/j.issn.2095-6134.2019.06.013

Abstract ( 429 ) PDF (KB) ( 7 )

A new method is proposed to address the challenging issues in spatial-temporal multi-dimensional visualization of ionospheric electron density. It is difficult to transmit multi-dimensional and multi-temporal ionospheric electron density data in a Web environment because the complexity and characteristics of the data are unable to meet the real-time visualization requirements, and the traditional surface rendering method can not be used to display the whole scene of the original data field. Based on the processing of ionospheric electron density source data, a video compression coding method is used to implement the efficient transmission of time series data. With the WebGL programmable rendering pipeline, the GPU-accelerated ray-casting-based volume rendering algorithm of ionospheric electron density is proposed. The adaptive step-size sampling method and the early light termination method are used to improve the visualization quality and volume rendering efficiency. Finally, based on the open source virtual earth platform Cesium, the multi-layer, dynamic, and interactive visualization of ionospheric electron density is successfully implemented. The feasibility and effectiveness of the proposed method are verified, and the proposed method provides technical support for scientific visualization and research of ionospheric electron density.

RB dynamic pre-allocation scheduling scheme for cellular Internet of Things

JIN Yeqi, ZHENG Min, TAN Chong, LIU Hong

2019, 36 (6): 825-831. DOI: 10.7523/j.issn.2095-6134.2019.06.014

Abstract ( 354 ) PDF (KB) ( 13 )

For high signaling overhead in dynamic scheduling, the LTE semi-persistent scheduling (SPS) is improved in combination with the machine traffic characteristics of cellular Internet of Things. We proposed a dynamic pre-allocation model of resource block (RB) and designed a corresponding scheduling algorithm. By using device buffers in combination with pre-allocation parameters instead of traditional grant scheduling, dynamic allocation of RBs for packets under low control channel usage rates reduces the resource waste. Simulation results show that the algorithm reduces the signaling overhead of scheduling, and the delay satisfaction and utilization of traffic channel under the limited control channel are better compared to the dynamic and semi-persistent scheduling algorithms.

A multichannel detection method for HF 3G-ALE signal based on Duffing chaotic oscillator

WU Peipei, ZHANG Min, SHI Yingchun

2019, 36 (6): 832-838. DOI: 10.7523/j.issn.2095-6134.2019.06.015

Abstract ( 308 ) PDF (KB) ( 3 )

Aiming at the problem that traditional methods make poor detection performance when implementing detection for HF 3G-ALE signal due to low signal-to-noise ratio and carrier frequency offset, we propose a multichannel detection method for non-cooperative communication countermeasure based on Duffing chaotic oscillator. Firstly, we employ the public preamble to make sliding correlation preprocessing for the intercepted signal. Then, the correlation operational signal is put through multiple detection channels, which combine the local oscillators of different angular frequencies and chaotic oscillators with the same built-in parameters. The change of oscillator's output state in the detection channels is taken as the basis of signal detection and carrier frequency estimation. Theoretical analysis and simulation experiment show that the proposed method effectively improves the detection performance for 3G-ALE signal, and reduces complexity of the conventional chaotic detection method to a certain extent.

Dissociation characteristics of bromoethane under external electric fields

JIN Yaru, LIU Yuzhu, DUAN Yiqun, ZHANG Xiangyun, YIN Wenyi, LIN Hua, ABULIMITI Bumaliya

2019, 36 (6): 839-843. DOI: 10.7523/j.issn.2095-6134.2019.06.016

Abstract ( 378 ) PDF (KB) ( 3 )

Bromoethane dissociates and generates the bromine radical under the radiation from the sun, which destroys the atmospheric ozone layer. So, it is necessary to take effective measures to degrade bromoethane. We use the density function theory (DFT) and calculate the dissociation properties and spectral characteristics of bromoethane under the external electric fields (0-0.028 5 a.u.) at the B3LYP/6-31G+(d,p) level. It is showed that the total energy of the molecule decreases as the external field increases from 0 a.u. to 0.028 5 a.u. along the Z-axis. Meanwhile, the energy gap decreases monotonically and the dipole moment increases. It is shown in the potential energy curves that the electric field of 0.030 a.u. is strong enough to break the C-Br bond. The results provide important information for the degradation of bromoethane under external electric fields.

A method of high accuracy 3D location of airborne repeat pass InSAR

DONG Xiaotong, HAN Chunming, YUE Xijuan, ZHAO Yinghui

2019, 36 (6): 844-850. DOI: 10.7523/j.issn.2095-6134.2019.06.017

Abstract ( 312 ) PDF (KB) ( 3 )

In realistic measurement of repeat pass interferometric synthetic aperture radar (RP-InSAR), two flight tracks do not coincide. The position shift and attitude of platforms keep changing. Irregular and obvious geomorphing is showed on interferometric complex images. It is difficult to calculate the 3D positioning of InSAR images. We analyzed the causes and effects of geometric distortions. A high precision positioning method is proposed, which is based on the high accuracy of InSAR imaging geometry. By correcting imaging parameters, the method achieves high accuracy 3D location of airborne RP-InSAR. InSAR image registration is achieved by extracting identical points. DEM with high accuracy is generated after interferometry. The high accuracy DEM is used to calculate the 3D positioning of InSAR images. Comparison between the measured positions and calculated positions of checkpoints shows that the proposed method is effective in solving the problem of 3D location of airborne RP-InSAR.

Current Issue