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Table of Content

    20 July 2021, Volume 57 Issue 4
    Hardware Optimization and Evaluation for Crucial Modules of Lattice-Based Cryptography
    CHEN Zhaohui, MA Yuan, JING Jiwu
    2021, 57(4):  595-604.  DOI: 10.13209/j.0479-8023.2021.054
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    To improve the efficiency of lattice-based cryptography in practical applications, the optimization technology of polynomial multiplication in lattice-based cryptography is proposed. The polynomial coefficients are stored in a ping-pong structure to improve the bandwidth. By eliminating pre-scale operations, 10.5% of modular multiplication operations and 16.7% of storage space are saved. The structure based on look-up table shift register and three-input adder is adopted to reduce the logical resource occupation. The pipeline structure with optional stages is designed to make the butterfly module in polynomial multiplication meet the timing requirements of different cryptographic hardware systems. The evaluation results show that the maximum frequency of low-area, balanced and high-performance implementations of the optimized butterfly unit can reach 150, 250 and 350 MHz, respectively. Compared with the existing implementation technologies, the optimized hardware implementation can achieve higher operating frequency with a smaller circuit area, which improves the efficiency of polynomial multiplication module by 22.8%. 
    A Dynamic Graph Convolutional Network Based on Spatial-Temporal Modeling
    LI Jing, LIU Yu, ZOU Lei
    2021, 57(4):  605-613.  DOI: 10.13209/j.0479-8023.2021.052
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    In order to learn high-level representation with rich information for dynamic graphs where nodes and edges change dynamically, a dynamic graph convolutional network (DyGCN) is proposed to learn representation as a mixture of both spatial and temporal information. The model performs spatial convolutions to learn structural information on graphs and temporal convolutions to learn historical information along time axis. Besides, the selfadapting mechanism on the spatial convolution layer allows model parameters to update with graphs. Extensive experiments on financial networks for edge classification tasks against financial crimes show that DyGCN outperforms state-of-the-art methods.
    Discrimination of Ripe, Unripe and Processed Rape Honey Based on Nuclear Magnetic Resonance Method with Chemometrics
    CHEN Hui, ZHANG Jialin, JU Jing, GAO Shuai, FAN Chunlin, ZHANG Zijuan
    2021, 57(4):  614-622.  DOI: 10.13209/j.0479-8023.2021.044
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    By investigating 80 samples of ripe, unripe and processed rape honey collected from three regions (Anhui, Inner Mongolia and Jiangsu) in China, a method based on NOESY 1D combined with O2PLS-DA was developed to discriminate the mentioned three types honey. NOESY 1D spectra of representative honey samples were first compared, and some obvious differences among the three types of honey were observed. O2PLS-DA model was applied to discriminate the collected samples successfully. The segmental bin was selected based on the greatest R2Y and Q2 values. Three types of honey from three regions could be successfully discriminated, although there was partially overlap among some of the unripe and processed honey samples, but they can be discriminated in 3D graph. The developed method could be used to identify ripe, unripe and processed honey from same region, all R2Y and Q2 are higher than 0.97 and 0.81, respectively. This method could be applied to discriminate the ripe, unripe and processed rape honey from the same region. The advantages of this method are small sample amount, short time, good reproducibility and reliable results.
    Synthesis of Pyrite FeS2 Nanospheres and Study on the Supercapacitor Performance
    LI Jianzhuo, CHUAN Xiuyun
    2021, 57(4):  623-631.  DOI: 10.13209/j.0479-8023.2021.058
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    Pyrite FeS2 nanospheres was synthesized through a simple solvothermal method in one step, and the electrochemical performance as the electrode material of supercapacitor was studied. The structure, morphology, specific surface area and pore volume of the material were characterized and measured experimentally, and its supercapacitor performances in three common electrolytes (6 M KOH, 6 M NaOH and 1 M Na2SO4) were tested by cyclic voltammetry (CV), galvanostatic charge/discharge (GCD) and electrochemical impedance spectroscopy (EIS). The results show that the product is homogeneous pyrite FeS2 nanospheres with a diameter of about 300?600 nm, showing obvious pseudocapacitance characteristics in all three electrolytes. When the electrolyte is KOH, it shows the highest specific capacitance, reaching 732.9 F/g at the current density of 2 A/g and 307.1 F/g at the current density of 20 A/g with the capacity retention rate of 41.9%. It is demonstrated that the synthesized FeS2 nanospheres is an excellent electrode material for supercapacitors. 
    Prediction of Dust Storm Frequency Variation in Inner Mongolia Region under Global Warming Scenarios
    YANG Shiyu, WEN Xinyu
    2021, 57(4):  632-644.  DOI: 10.13209/j.0479-8023.2021.042
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    The authors reconstruct a new dust storm series on daily basis for Inner Mongolia Region covering the period 1860?2100, by applying a newly developed artificial neural network model onto CMIP5 results from historical and RCP runs. The authors investigate the new series and suggest that the number of China’s dust storms keeps decreasing in both RCP 2.6 and 8.5 scenarios; the proportion of dust storms with large impact area also decrease; the decreasing is more evident in the warmer RCP8.5 scenario than that in RCP2.6; the phase-lock features, i.e. maximum occurrence frequency of dust storms in April every year, remain unchanged in both global warming scenarios. 
    Prediction of PM2.5 Daily Concentration of Guangzhou Based on Neural Network Algorithms
    LI Zequn, WEI Jun
    2021, 57(4):  645-652.  DOI: 10.13209/j.0479-8023.2021.050
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    Autoregressive integrated moving average (ARIMA) model, back propagation (BP) neutral network and long short-term memory (LSTM) are used to predict the daily concentration of PM2.5 in 2019 in Guangzhou city of China from 2015 to 2019. The effect of ensemble empirical mode decomposition (EEMD), temporal resolution on model prediction is explored in this paper. The results show that EEMD is able to improve significantly the prediction ability of the model on the low-frequency part of PM2.5 sequence. Increased temporal resolution can improve the prediction accuracy, with more input data. Since PM2.5 (t-1) is used as the input data, the model can only predict PM2.5 for 1 day in advance. To increase the prediction time window, we adopt a rolling forecast method, using PM2.5 (t) prediction value as the input data for PM2.5 (t+1). The result shows that the rolling forecast method allows the model to forecast PM2.5 (t+n) with a comparable MAE compared to the experiment without the rolling forecast method. In this paper, the ARIMA model (the time accuracy of input data is 6 hours) has the best prediction accuracy, and the minimum MAE value can reach 6.478. 
    Three Dimensional Fault Enhancement Technique Based on Multi-directional Recognition
    AN Shengpei, CHEN Yanyang, LUO Hongmei, YAN Shicui
    2021, 57(4):  653-659.  DOI: 10.13209/j.0479-8023.2021.057
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    In order to apply the fault enhancement method to improve the accuracy of fault identification, a three-dimensional fault enhancement method based on multi-directional recognition is developed. This method applies directional filtering to enhance the continuity of the seismic events and suppress the background noise, and applies edge-preserving filtering to preserve the fault information in seismic profiles. This method is further improved in two aspects. 1) Multi-directional fault recognition is designed to adapt to the presence of inclined formations. 2) The two-dimensional fault enhancement method is extended to the three-dimensional one which achieves the effect of three-dimensional fault enhancement with a lower amount of calculation. The applications on synthetic data and the three-dimensional post-stacked actual data show that the proposed method can effectively suppress the background noise, enhance the continuity of the seismic events, and improve the resolution of the fault image, which is conducive to the subsequent structural interpretation.
    Response of Leaf Amino Acids of Understory Shrubs to Nitrogen Addition in Primary Forest and Secondary Forest of Mt. Jianfengling
    LI Xiuping, AN Lihua, NI Xiaofeng, JI Chengjun
    2021, 57(4):  660-670.  DOI: 10.13209/j.0479-8023.2021.043
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    In order to further understand of the plants response and adaptation mechanism to nitrogen addition in primary and secondary tropical montane rain forests, the authors conducted a nitrogen addition experiment in the primary and secondary forests in Mt. Jianfengling respectively, setting three nitrogen addition treatments (0, 50 and 100 kg N/(ha·yr)) in each forest, to explore the effects of enhanced nitrogen addition on amino acid content in leaves of understory shrubs. The results showed that when no nitrogen was added, the contents of total amino acids and hydrolyzed amino acids in primary forest and secondary forest were not significant, while the content of free amino acids in primary forest was significantly higher than that in secondary forest. When middle nitrogen was added, the response of leaf amino acid content of understory plants in secondary forests was higher than that in primary forests. When high nitrogen was added, there was no significant difference in the response of hydrolyzed amino acids of understory shrubs in primary forest and secondary forest, but the response of free amino acids in understory shrubs in primary forests was higher than that in secondary forests. 
    Spatial Distribution and Influencing Factors of Unsafe Charging for Electric Bicycles in Urban Areas
    LIAO Cong, WU Lun, CAI Heng, CHEN Yueyi, TIAN Yuan
    2021, 57(4):  671-678.  DOI: 10.13209/j.0479-8023.2021.019
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    By using spatial hot spot analysis and spatial error regression model, the authors analyzed the spatial distribution pattern and the influencing factors of unsafe charging behavior for e-bikes in Guangming district of Shenzhen, with the daily inspection data collected in urban grid management. Urban spatial features, such as land use types, employment opportunities, facility and traffic conditions were found to have a close correlation with unsafe charging behaviors at different significance levels. There was a certain spatial autocorrelation of the unsafe charging behavior of e-bikes. Most of the unsafe charging concentrated in a few grids, and 9.2% of the grids in the case area covered 84.94% of the total number of unsafe charging behaviors. Variables related to travel demand and traffic conditions have a stimulating effect on people's behavior of illegal charging of e-bikes. There was a positive correlation between the proportion of residential land, the number of enterprises and the road density within the urban grid and the unsafe charging behaviors of e-bikes. The standardized regression coefficients were 0.09, 0.03 and 0.02 respectively. There was a negative correlation between the proportion of public facilities and public building land in urban grid, the distance from home to primary schools and the unsafe charging behaviors of ebikes, and the standardized regression coefficients were ?0.02 and ?0.01. Higher coverage rate of bus stop would reduce the use of e-bikes, and lead to less unsafe charging behaviors. The results can be used to direct the optimization of patrol routes in grid management and improve the ability of pre-perception and fine prevention of urban fire accidents. 
    Spatial Distribution Characteristics and Risk Assessment of Heavy Metals in Shenzhen Coastal Areas
    ZHANG Haijun, SHI Benning, JIAO Xueyao, WU Hailun, ZHOU Lin, SHEN Xiaoxue, LI Ruili
    2021, 57(4):  679-690.  DOI: 10.13209/j.0479-8023.2021.032
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    This study analyzed the spatial distribution characteristics of heavy metal pollution in seawater and surface sediments in Shenzhen coastal areas by literature retrieval methods. The WQI (water quantity index), Species Sensitivity Distribution method, and potential ecological risk index method were applied to conduct the ecological risk assessments of heavy metal pollution in seawater and surface sediments. The results showed that: 1) The contents of Hg, Cu, Pb, and Cd in the seawater of the west was higher than that of the east, which may be related to the development of the west, more pollution and the poor water exchange of water in the Shenzhen Bay. 2) Based on the first category of Sea Water Quality Standard, WQI>1 indicated that there was no clean water in Shenzhen coastal areas; the ecological risk of heavy metals in offshore water was mostly at high or medium risk levels, in the order of Cu>Hg>Cd>Pb. 3) The contents of heavy metals Cd, Cu, Zn, Pb and Cr in the surface sediments of Shenzhen coastal areas decreased from the northwestern Pearl River Estuary to the southeastern seas; the pollution of Hg and As was concentrated in the Shenzhen Bay and the eastern seas; heavy metal pollution in surface sediments was closely related to the frequent human activities and consistent with the distribution in seawater. 4) The comprehensive potential ecological risk of heavy metals in surface sediments in Shenzhen coastal areas was extremely high, with Cd having the highest ecological risk, followed by Cu and Hg. 
    Quantitative Assessment on Supply-Demand Budget of Culture Ecosystem Service: A Case Study in Pinglu Swan Scenic Spot
    YANG Liwen, WANG Dayong, LI Shuangcheng
    2021, 57(4):  691-698.  DOI: 10.13209/j.0479-8023.2021.040
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    Taking Pinglu Swan Scenic Spot as an example, the supply-demand relationship of cultural ecosystem service (CES) was assessed. The supply of CES was rated by the annual capacity of tourist reception, and the demand was calculated through importance value acquired by questionnaire. The results were showed as follows. 1) The overall demand of CES was positively correlated with GDP per square kilometre and population density, meanwhile it was also related to the understanding of CES. However, it had no relevance to distance. Owing to continuous loss of biodiversity from global climate change and human activities, the demand for bird-watching service, aesthetic value and existence value were relatively high, which suggested that people attached much importance to the biodiversity conservation. 2) The supply capacity of CES of Pinglu Swan Scenic Spot was generally higher than the overall demand, so the demand was the chief factor that affected the supply-demand relationship. The supply-demand matched areas were distributed in Xi’an City and Zhengzhou City, while the other 13 cities demonstrated a mismatched relationship. Enhancing the propoganda and education, as well as improving traffic service of Pinglu Swan Scenic Spot will raise demand so as to narrow disparities between supply and demand of CES. The results provide data support for environmental planning and management of wetland resources. 
    Relations between Structural Properties of Endorheic Rivers and Basin Characteristics in Eastern Inner Mongolia Plateau
    LIU Danlu, WANG Yichu
    2021, 57(4):  699-706.  DOI: 10.13209/j.0479-8023.2021.047
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    Based on the river networks extracted from DEM at 30 m resolution, the relations between structural characteristics of endorheic rivers and basin properties in the eastern Inner Mongolia Plateau were analyzed. The results show that rainfall and potential evaporation are both closely related to structural parameters of rivers. Basin underlying surface conditions also affect the structure of endorheic rivers. Specifically, basin slope promotes the branching of river networks, whereas arid and semi-arid grass plants suppress the development of endorheic rivers.
    Construction Land Expansion and Its Driving Force in Highly Urbanization Areas: A Case Study of Shenzhen City
    WANG Hongliang, GAO Yining, WU Jiansheng, WANG Na, ZHAO Yuhao, PENG Zifeng, WANG Yanglin
    2021, 57(4):  707-715.  DOI: 10.13209/j.0479-8023.2021.045
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    Based on the survey data of land use change, this paper studies the process and characteristics of urban construction land expansion in Shenzhen from 1996 to 2016 by analyzing the spatial and temporal changes, expansion intensity and landscape pattern of urban construction land, and reveals the spatial differentiation of urban construction land expansion in highly urbanized areas. Regression analysis model is used to explore the driving mechanism of social and economic factors on the expansion of construction land. The results show that the expansion of construction land in Shenzhen presents a continuous growth trend, and the expansion mode of new construction land is significantly different. Futian District and Luohu District are mainly expanded by interior filling, while Nanshan District and Baoan District are mainly expanded by external expansion. The difference between construction land extension intensity in different regions and the index of landscape pattern indicates that the spatial expansion of construction land is gradually changing from disorder, homogeneity, inefficient spread to orderly, heterogeneous and efficient utilization. Social and economic factors have a significant positive correlation with construction land expansion. The regression coefficient of resident population is the largest (0.578), and that of fixed assets investment is the smallest (0.000). Pearson correlation ranking is Resident population > Industrial structure >GDP> Fixed asset investment, indicating that population plays a decisive role in the expansion of construction land, and fixed asset investment is embodied in the function of connection. 
    Quantitative Source Analysis of Waterlogging on Urban Roads Based on a 1D and 2D Coupling Waterlogging Model
    WU Junyi, QIN Huapeng
    2021, 57(4):  716-722.  DOI: 10.13209/j.0479-8023.2021.033
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    To simulate the influences of road surface runoff and drainage system overflow on road waterlogging, 2D surface runoff model is adopted for road catchment areas, 1D model is adopted for other catchment areas and underground pipe networks, and then a 1D and 2D coupling waterlogging model is developed based on PCSWMM. A quantitative source analysis method for road waterlogging is also proposed, which takes the contribution ratio of surface runoff from local road or overflow from drainage system to road waterlogging water as the indexes. After calibration and validation based on the measured water level in the manholes and the measured waterlogging depth on the road, the model is used to simulate the road waterlogging in a drainage area of Nanshan District of Shenzhen City under designed storm events. The results indicate that there are four main road waterlogging points (A, B, C, D) in the study area; overflow occurs on two points (A, D) under the storm event with a return period of 5 years, the overflow volume accounts for 24% and 61% of the total volume of waterlogging water respectively; while overflow occurs on three points (A, C, D) under the storm event with a return period of 50 years, the overflow volume accounts for 49%, 62%, and 73% of the total volume of waterlogging water, respectively; and the contribution of the overflow volume from manholes to the total waterlogging volume increases as the storm intensity increases. The dynamic change of road waterlogging is comprehensively affected by many factors such as the sources of waterlogging water, downstream blockage, local terrain and so on. For the waterlogging points where overflow volume accounts for a large amount of waterlogging water, it is recommended to improve the drainage capacity of the drainage system and promote the sponge city construction in the upstream catchment; for the waterlogging points where the local road surface runoff volume accounts for a relatively large amount of waterlogging water, it is recommended to promote the sponge city construction in the local area, and properly modify the local terrain or increase pump stations for drainage. 
    Dynamics of Photosynthetic Active Radiation and Photosynthetic Characteristics of Rice Leaves at Two Canopy Heights
    ZHU Ting, KANG Huixing, KE Xinran, ZHANG Yan
    2021, 57(4):  723-732.  DOI: 10.13209/j.0479-8023.2021.046
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    The purpose of this study is to explore the potential changes in the relationship between dynamic light and photosynthesis in high CO2 environment, so as to provide scientific support for coping with global changes. We characterized dynamic light environment at two heights within rice canopy and dynamic photosynthetic response of leaves at each height (about 45 cm or 90 cm high from the soil of paddy field) in an open canopy and within an open top chamber (OTC) with a high CO2 of 600 μmol/mol air. The result showed that the averaged photosynthetic photon flux density incident at 90 cm height above the paddy field was 3–4 times higher than that at 45 cm height, but the coefficient of temporal variation in light received at 90 cm height was 55%–60% smaller than that of the lower layer. Flag leaves at 90 cm height showed higher saturated photosynthetic rate and more postillumination CO2 fixation, while leaves at 45 cm height showed higher photosynthetic rate under low light. In the high CO2 OTC, light attenuation percentage in canopy tended to increase, compared with leaves outside the OTC; the difference between assimilation rates at the two heights also increased within the OTC. These results suggested that not only the steady-state photosynthetic rate, but also the dynamic photosynthesis in rice leaves may have altered in different ways at different canopy heights, which is to be further influenced by CO2 environment. 
    Isolation and Identification of a 2,4-Dinitrotosylate Degrading Strain and Its Degradation Characteristics
    XU Wenjie, ZHAO Quanlin, LUO Minghan, YE Zhengfang
    2021, 57(4):  733-738.  DOI: 10.13209/j.0479-8023.2021.048
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    Due to the shortage of bacteria resources for bioremediation of TNT red water polluted soil, a 2,4-dinitrotoluene sulfonates degrading strain X2 was isolated from a commercial microbial consortium. Based on the 16S rDNA sequence analysis and the physicbiochemical characteristics, strain X2 was identified as Sphingobium sp.. The growth experiments were carried out to optimize the growth condition of X2. The biodegradation mechanisms of 2,4-DNT-3-SO3- and 2,4-DNT-5-SO3- by X2 and its biodegradation ability towards other niro-aromatic explosives were investigated. The results showed that the optimum growing conditions for X2 were 30oC, pH=7 and 1% salinity. The removal efficiencies of 2,4-DNT-3-SO3- and 2,4-DNT-5-SO3- reached 100% after 12 and 3 days, respectively. Liquid chromatography-mass spectrometry analysis showed that the nitro groups in dinitrotoluene sulfonates were transformed to amino groups. Sphingobium sp. X2 has broad-spectrum degradation characteristics. It can degrade not only dinitrotoluene sulfonates, but also other nitroaromatic pollutants like 2,4,6-trinitrotoluene, dinitrotoluene and mononitrotoluene, providing possibilities for TNT red water bioremediation. 
    Estimation of Agricultural Non-point Source Pollution Loads Based on Improved Export Coefficient Model
    HU Qing, GUO Huaicheng, WANG Yuqi, ZHANG Yang, LI Zheng, FU Zhenghui, LU Wentao
    2021, 57(4):  739-748.  DOI: 10.13209/j.0479-8023.2021.049
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    The Dianchi watershed Basin was selected as a typical watershed. Considering the differences of regional natural geography, hydrometeorology and human activities, using 1 km×1 km grid data, the detailed simulation calculation of the pollutants entering the water source of agricultural sources is carried out. The rainfall driving factors, terrain driving factors, surface runoff factor, underground storage/groundwater runoff factor and interception factor are obtained. The average comprehensive water inflow coefficients of TN and TP from agricultural sources in Dianchi Basin in 2016 are 0.447 and 0.342 respectively, and the actual water inflow loads of TN and TP from agricultural sources in 2016 are 577.39 t and 167.62 t respectively. The results show that the discharge of agricultural source pollutants and the load of influent water have significant spatial variation in Dianchi Lake Basin. 81.0% of nitrogen and 74.2% of phosphorus were concentrated in Caohai land area and the north coast of the open sea. The largest emission was in the upper reaches of Panlong River, with nitrogen and phosphorus accounting for 21.9% and 20.2% respectively. It is also found that livestock and poultry breeding account for more than 90% of the total TN and TP emissions of from agricultural sources, which should be the focus of agricultural source pollution control. 
    Consistency Evaluation of Ecological Carrying Capacity and Industrial Layout Based on “Three Lines One Permit” Index System
    LU Wentao, YIN Caichun, ZHANG Yang, FU Zhenghui, GUO Huaicheng, YU Lei, LIU Yi
    2021, 57(4):  749-755.  DOI: 10.13209/j.0479-8023.2021.061
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    Combined with the work of “Three Lines One Permit” in China, this study constructed a corresponding index system, and selected Qingpu District of Shanghai as the case study area to evaluate the consistency of regional ecological carrying capacity and industrial layout by both single factor and comprehensive index methods. The results show that: 1) the single factor ecological carrying rate can reflect the key limiting factors, while the comprehensive index can directly show the cumulative impact of regional industries on ecological carrying capacity; 2) the conflict between industrial layout and ecological space and soil environmental quality is less in Qingpu District, but the contradiction between industrial layout and water, atmospheric environment is prominent, which results in the overload of ecological environment and the disharmony between ecological carrying capacity and industrial layout; 3) the regions with prominent consistency problems are basically the same as the key units of environmental control, indicating that the index system is objective and feasible, can provide reference for relevant evaluation and research work, and has the feasibility of nationwide promotion. It is suggested to strengthen pollutant emission control for the key control units. 
    Growth Conditions of a Hydrogen-Oxidizing Bacterium and Its Utilization of Different Nitrogen Sources
    TAO Huchun, XIE Yong, ZHANG Lijuan, DING Lingyun, CHEN Yizhen
    2021, 57(4):  756-764.  DOI: 10.13209/j.0479-8023.2021.059
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    An autotrophic hydrogen-oxidizing bacterium, named Rhodoblastus sp. TH20, was successfully enriched and isolated from municipal activated sludge in a domestic wastewater treatment plant. With simulated ammonium-containing wastewater as culture medium, the strain could utilize H2 and CO2 as energy and carbon sources respectively and the growth conditions were optimized at 25℃, 160 rpm and pH=7.0. At initial concentration of 100 mg/L, efficient ammonium removal (>99%) was achieved within 72 hours. Up to 77.8% of ammonium was assimilated to organic nitrogen and stored intracellularly, while the rest ammonium was transformed to gaseous N2. These results indicated that Rhodoblastus sp. TH20 was able to efficiently convert ammonium into microbial protein, thereby providing a sustainable pathway of wastewater treatment. 
    Removal of Two Quinolone Antibiotics from Aqueous Solution by the Municipal Sewage Sludge-Based Adsorbent
    TAO Huchun, GONG Yiwei, ZHANG Lijuan, DING Lingyun, ZHANG Shanfa
    2021, 57(4):  765-772.  DOI: 10.13209/j.0479-8023.2021.060
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    The municipal sewage sludge was used as an raw material to prepare the sewage sludge-based adsorbent (SSA) by HNO3 activation, NaOH activation and H2O2 oxidation modification. The removal of ciprofloxacin (CIP) and lomefloxacin (LOM) from aqueous solution and the influencing factors were studied. Scanning electron microscopy and Fourier transform infrared spectroscopy were used to characterize the microstructure and functional groups on the surface of SSA. The effects of adsorbent dosage, temperature, the initial pH of solution, the ionic strength and other factors on the removal of CIP and LOM by SSA were investigated. The results showed that the modified SSA activated by 0.1 M HNO3 was most effective for removal of CIP and LOM. The rough structure of the modified adsorbent could provide more sites for antibiotic adsorption, and the oxygen-containing functional groups were able to form hydrogen bonds to enhance the adsorption of organic matters in solution. When the antibiotic concentration was 10 mg/L, the adsorption capacity of CIP and LOM was 8.95 and 7.28 mg/g, and removal rates were 90% and 73%, respectively. The adsorption process of CIP and LOM on the modified SSA was in accordance with the pseudo-second-order model, and Langmuir isotherm equation could well describe the adsorption behavior of CIP and LON on the modified SSA, which proved that adsorption process was monolayer chemisorption. The adsorbent removed 84% CIP and 67% LOM after 5 cycles, thus providing an efficient and sustainable way of antibiotic removal. 
    Livestock Keeping of Migrant Households from Perspective of Livelihood and Ecology: A Case Study in Yushu Tibetan Autonomous Prefecture, Qinghai Province
    LI Mingjing, QI Yingjun, LI Wenjun
    2021, 57(4):  773-782.  DOI: 10.13209/j.0479-8023.2021.055
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    To understand the behavioral logic and ecological impacts of livestock keeping of migrant households under the background of urbanization in pastoral areas, three villages of Yushu Tibetan Autonomous Prefecture Qinghai Province were selected as the case study sites, and the data were obtained through questionnaires and interviews. The forms and reasons of livestock keeping were presented, the change of livestock population and herd’s perception were evaluated, and influencing factors of livestock keeping were further explored based on the Scott’s safety-first principle of moral peasant. The results show that migrant households kept livestock as an adaptation strategy to urbanization through division of labor, entrusting to kins or employing herders. Households kept livestock mainly for safety need and households with higher income also showed the characteristics of rational peasant. Household with larger family size and non-living causes to migrate were more inclined to keep livestock. Household with higher income had higher probability of keeping livestock and more livestock, while households with more members employed had a lower probability of keeping livestock. This adaptation strategy was restricted by factors such as social relations and economic cost and seems difficult to sustain. Though livestock keeping of migrant households did not increase grazing pressure, the attentions should be paid to the specific form of livestock keeping, the possibility of migrant herders to move back, the change of behavioral logic and the animal husbandry of non-migrant households to achieve the goal of reducing livestock through encouraging herders to migrate to the urban.
    Responses of Vegetation Growth to Climate Change in Permafrost Distribution Region in Northeast China
    LI Yunyun, LIU Hongyan
    2021, 57(4):  783-789.  DOI: 10.13209/j.0479-8023.2021.056
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    The interannual change rate of the normalized vegetation index (NDVI) and its correlation with climate factors were compared under different permafrost degradation and vegetation types. The results indicated that NDVI of the coniferous forest accelerated, which was positively correlated with the temperature and negatively with the precipitation in the growing season. As the permafrost active layer deepens, the rate of increase in NDVI of coniferous forests gradually decreases from north to south. The grassland NDVI accelerated in non-permafrost regions, which was positively correlated with growing season precipitation. There is a clear difference between the response of mixed forests to climate in permafrost and non-permafrost regions. In permafrost regions, mixed forest NDVI is positively correlated with growing season temperature and negatively correlated with growing season precipitation. As the permafrost active layer deepens, the correlation coefficient between the NDVI of mixed forest and growing season temperature shifts from positive to negative, and the correlation coefficient with growing season precipitation shifts from negative to positive. This may be related to the different water supply caused by different active layer thickness. The results imply that under the coupling effects of climate and permafrost, climate warming will lead to gradual northward shifting of coniferous forests and mixed forests, and occupation by grasslands in non-permafrost regions.
    Pruning and Fine-tuning Optimization Method of Convolutional Neural Network Based on Global Information
    SUN Wenyu, CAO Jian, LI Pu, LIU Rui
    2021, 57(4):  790-794.  DOI: 10.13209/j.0479-8023.2021.053
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    In order to solve the problem that convolutional neural network is large and the accuracy loss of the model pruning method is relatively serious, a fine-tuning optimization method for model pruning is proposed. The global information of the original convolutional neural network model is introduced to the post-prune model to make it store the original model information which improves the accuracy of the model after pruning. Experimental results show that for the image classification tasks and target detection tasks, proposed fine-tuning optimization method can obtain greater compression ratio and smaller model accuracy loss.