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Nonlinearity Strength Indicators for Numerical Simulation Based Load Reduction-Water Quality Responses
SU Han, ZOU Rui, LIANG Zhongyao, YE Rui, WANG Zhiyun, LIU Yong
Acta Scientiarum Naturalium Universitatis Pekinensis    2023, 59 (4): 695-703.   DOI: 10.13209/j.0479-8023.2023.036
Abstract153)   HTML    PDF(pc) (799KB)(80)       Save
This study developed four nonlinearity strength indicators for water quality responses based on cross sample entropy, Fourier transformation, non-sequence counting, and adjusted R2 according to typical nonlinear load reduction-water quality responses suggested by previous studies. All the indicators were applied on typical numerical water quality simulation samples. Based on the calculation, the four indicators were compared with each other to provide suggestions on how to use them to detect the nonlinearity and measure the nonlinearity strength. Results show some overlaps among the four indicators, however, they are not interchangeable. The four indicators suggest seasonal differences, peak changes, short-term water quality deterioration, and averaged water quality changes respectively. After providing suggestions on how to use the four indicators to detect nonlinearity of water quality responses, this study further discusses the limitations on the nonlinearity definition and potential applications of the four indicators. This study will contribute to understanding, distinguishing, and analyzing the type of nonlinear water quality responses.
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Global Sensitivity Analysis of Hydrological Parameters of the Watershed Simualtion Model
CAI Kaikui, LI Jincheng, HU Mengchen, MA Wenjing, YE Rui, LIU Yong
Acta Scientiarum Naturalium Universitatis Pekinensis    2022, 58 (4): 753-762.   DOI: 10.13209/j.0479-8023.2022.052
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A hydrological simulation model was developed for the Dashetai watershed in the Inner Mongolia Autonomous Region with LSPC (Loading Simulation Program in C++). Two global sensitivity analysis (GSA) methods, Morris and Sobol, were applied to identify hydrological sensitive parameters and sensitive surface landuse types. The impacts of two GSA methods and model output measures on sensitivity analysis results were also evaluated. The main conclusions are as follows. 1) The model has a good fit for daily and monthly runoff simulation. The R2 of the simulated value and the observed value is greater than 0.6, and NSE between them is greater than 0.5, which indicates that LSPC model is suitable for hydrological simulation of inland arid and semiarid areas. 2) The two GSA methods have impacts on the identification of sensitive parameters and the ranking of sensitive indexes; while the impact of the two measurement methods of MAE and MSE is mainly reflected in the identification of sensitive parameters. 3) The sensitive hydrological parameters are lower zone nominal storage (LZSN) and active groundwater evapotranspiration (AGWETP), and the sensitive underlying landuse types are grassland, farmland, forest and water. All have close relationships with precipitation and landuse types in the study area.
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Drug-Target Interactions Prediction Based on Meta-path of Heterogeneous Information Network
LIAO Yiming, OUYANG Chunping, LIU Yongbin, HU Fuyu
Acta Scientiarum Naturalium Universitatis Pekinensis    2022, 58 (1): 37-44.   DOI: 10.13209/j.0479-8023.2021.105
Abstract666)   HTML    PDF(pc) (653KB)(187)       Save
The paper proposes a graph neural network model based on meta-path to predict drug target interactions (GMDTI). Firstly, based on drugs, targets, diseases and side effects in eight datasets, and the eight different types of action relationships between them, the authors construct a drug-target heterogeneous information network (HIN). Then, two different meta-paths are defined to capture the different sub-topology information of HIN and the latent semantic information between different nodes. Especially, the graph neural network method is applied to represent the node by aggregating the information of the first-order neighbor nodes and the nodes of the meta-path. Finally, DTIs prediction is completed effectively by end-to-end learning method. This method takes the first-order topology and the semantic information of meta-path of the drug-target HIN into account, which is helpful to learn more potential drug target relationships. The experiment results show that the proposed method achieves 98.6% in AUC and 94.5% in AUPR, which are higher than all baseline models. At the same time, GMDTI has better robustness than all baseline models by sparsity experiments of datas and reduction experiments of noise.
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Simulation Study on Nitrogen and Phosphorus Reycling Response of Changing Dissolved Oxygen Concentration in Lake Dianchi
HU Mengchen, ZHU Tao, JIANG Qingsong, ZOU Rui, WU Zhen, ZHANG Xiaoling, YE Rui, LIU Yong
Acta Scientiarum Naturalium Universitatis Pekinensis    2021, 57 (3): 481-488.   DOI: 10.13209/j.0479-8023.2021.024
Abstract662)   HTML    PDF(pc) (5937KB)(174)       Save
A three-dimensional hydrodynamic-water quality model of Lake Dianchi was used to simulate the dynamic process of lake hydrodynamics and water quality, identify the characteristics of dissolved oxygen (Do) in the lake water. Combined with the setting of the external load reduction scenario, the effects of dissolved oxygen on the endogenous release of sediment and the cycle of nitrogen and phosphorus were explored. The results are conckyded. 1) The severe hypoxia in Lake Dianchi from June to September is caused by a combination of algae outbreaks and obstructed oxygen transport in the water. 2) Dissolved oxygen regulates the release of nitrogen and phosphorus nutrients in the sediment, and then significantly affects the concentration of nitrogen and phosphorus in the bottom water. 3) The improvement of the hypoxia condition at the bottom of the lake has high requirements on the reduction of external load. 4) The dissolved oxygen concentration at the phosphorus absorption-release equilibrium point of the sediment is about 3.3 mg/L, and the change in nitrogen concentration in Lake Dianchi is more susceptible to external load.
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Seasonal and Spatial Variations of Phytoplankton Communities and Correlations with Environmental Factors in Lake Dianchi
FENG Qiuyuan, WANG Shuran, LIU Xueqin, LIU Yong
Acta Scientiarum Naturalium Universitatis Pekinensis    2020, 56 (1): 184-192.   DOI: 10.13209/j.0479-8023.2019.128
Abstract872)   HTML    PDF(pc) (744KB)(165)       Save
The spatial and seasonal variations of environmental factors and phytoplankton community in Lake Dianchi was investigated. The statistical analysis found that a total of 84 phytoplankton taxon, belonging to 49 genera 6 phyla were identified, of which Chlorophyte were the most abundant, accounting for 59.2%, followed by Cyanophyta, accounting for 16.67% and diatom accounting for 5.95%. The trend of seasonal variation of algae density and biomass was not the same, which was caused by the biomass differences of various species. The Shannon Wiener index (H) was very small throughout the year, and seasonal variation was not significant. Algae density and biomass were positively correlated with total phosphorus (TP), and negatively correlated with nitrate (NO3-) and nitrogen phosphorus ratio (N:P). H was positively correlated with NO3- and N:P, while negatively correlated with TP. Nutrients had great influences on the density and biomass distributions of various taxa of phytoplankton community. The density and biomass of the most dominant species Microcystis sp. had the same relationships with the environmental factors, which were positively correlated with pH, TP and ammonia (NH4+), and negatively correlated with NO3-, N:P, total nitrogen (TN), dissolved organic carbon (DOC) and total organic carbon (TOC). Some biological factors may cause stronger effects on density and biomass distribution of chlorella and diatom, such as interspecific competition and predation, covering the influences of environmental factors.
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Clustering of Lake Variables Based on Pattern Recognition Method
REN Tingyu, LIANG Zhongyao, CHEN Huili, LIU Yong
Acta Scientiarum Naturalium Universitatis Pekinensis    2019, 55 (2): 335-341.   DOI: 10.13209/j.0479-8023.2019.001
Abstract743)   HTML    PDF(pc) (2519KB)(278)       Save

The self-organizing feature map (SOFM) and random forest (RF) method were integrated to recognize water quality patterns of nine water quality indicators for 63 lakes in China for 11 years (5110 data). The SOFM was built firstly to cluster lakes to identify the pollution conditions. Then, the RF was used to explore the good-offitness of water quality variables on the clustering result and to determine the important water quality indicators. The result of SOFM shows that the lakes can be clustered into three types. And the result of RF shows that permanganate index and chlorophyll a can determine the pollution condition when the classification accuracy is 80%. The integrated method can identify the water quality indicators reflecting the pollution conditions from complex data. In practice, the method can be used to determine the pollution conditions and direct the monitoring indicators.

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Impact of Tibetan Glacier Change on the Asian Climate during the Last Glacial Maximum
WU Yubin, LIU Yonggang, YI Chaolu, LIU Peng
Acta Scientiarum Naturalium Universitatis Pekinensis    2019, 55 (1): 159-170.   DOI: 10.13209/j.0479-8023.2018.094
Abstract1052)   HTML    PDF(pc) (3594KB)(238)       Save

Taking the climate of the Last Glacial Maximum (about 26000 years ago to 19000 years ago) as the background climate, the authors study the climatic impact of the expansion of the glacier on the Tibetan Plateau using the atmospheric general circulation model CAM4 coupled to the land surface model CLM4. The results show that in summer the increased glacier extent over Qinghai-Tibet Plateau has a significant impact on the climate in the Northern Hemisphere. Besides the significant temperature decrease on the glacier, atmospheric teleconnection can also cause significant warming near the Bering Strait. In addition, the disturbance caused by glaciers will enhance the South Asian summer monsoon and increase the precipitation there. Finally, through comparing the influence of the scale of the Qinghai-Tibetan glaciers on the climate under the different climate states of the Last Glacial Maximum (LGM) and Pre-industrial (PI) periods, it was found that their influence in the PI period was significantly less than that in the LGM period. It indicates that impact of Tibetan glaciers on climate is related with the climate state.

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Exploring Recovery Time of Eutrophic Lakes with a Minimal Phosphorus Recycling Model
WU Sifeng, LIANG Zhongyao, LIU Yong
Acta Scientiarum Naturalium Universitatis Pekinensis    2018, 54 (5): 1095-1102.   DOI: 10.13209/j.0479-8023.2018.043
Abstract711)   HTML    PDF(pc) (722KB)(198)       Save

To investigate the nonlinearity between recovery time of eutrophic lakes and the intensity of external load reduction, as well as the factors that could modify this time span, a quantitative analysis was conducted by model simulation. The authors employed a widely-applied phosphorous recycling model, and calculated the recovery time of a eutrophic lake to revert to clear state under different reduction rate. The parameters were set to different values to uncover how different attributes of the lake ecosystem could influence the recovery time. The model results showed that, there was a significant nonlinear relationship between load reduction and recovery time. When the external load reduced to slightly below the threshold, the recovery time would be longer than 40 years. Increasing reduction rate would result in significant decrease in recovery time, while its marginal effect became less significant. Lake type and morphology has significant influence on recovery time. Under the same reduction rate, recovery time of deeper lakes in colder regions is shorter; high sediment release rate requires longer recovery time; and longer hydraulic retention time leads to longer recovery time. Therefore, ecological remediation to reduce sediment release, or improve the hydro-dynamic conditions, may be effective. Moreover, this would both lower the threshold for clear phase, which lead to lower load reduction, and also shorten the recovery time, which made the remediation much easier.

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A System Dynamic Forewarning Model of Watershed Dual Water Resources Carrying Capacity
GAO Wei, LIU Yong, HE Shuzhuang
Acta Scientiarum Naturalium Universitatis Pekinensis    2018, 54 (3): 673-679.   DOI: 10.13209/j.0479-8023.2017.177
Abstract857)   HTML9)    PDF(pc) (5388KB)(189)       Save

The paper defined the concept of dual water carrying capacity based on water balance of different water quality and addressed a new method of determining forewarning classification according to timing of water shortage. A forewarning model of dual water carrying capacity was established based on system dynamics model. Taking the upstream of Niulanjiang watershed as a case study, the dual water carrying capacity was assessed and predicted by the model. Results show that under business as usual scenario, water resources of high quality will reach blue early warning and that of ordinary quality will reach yellow early warning. To meet the requirement of water diversion in the area, only low rate of socioeconomic development can be sustained in the area while environment protection measures has to be made at medium or above level.

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Object-Oriented Precise Decision-Making (OOPD) for Water Quality Improvementin Lake Yilong
ZOU Rui, SU Han, YU Yanhong, WANG Junsong, YE Rui, LIU Yong
Acta Scientiarum Naturalium Universitatis Pekinensis    2018, 54 (2): 426-434.   DOI: 10.13209/j.0479-8023.2017.164
Abstract994)   HTML2)    PDF(pc) (2337KB)(450)       Save

A framework called Object-Oriented Precise Decision-making (OOPD) was proposed which oriented to the lake itself. The framework was based on Numerical Source Apportionment powered by 3-dimensional water quality model, which then quantified the causality of water quality improvement and load reduction. The proposed framework was applied to support short-term decision making of Lake Yilong, a eutrophic lake. Results showed that Chenghe sub-watershed and Chengbeihe sub-watershed were important pollution source no matter considering which monitoring station and under which water diversion scenario. In addition, comprehensive pollution control should be considered to ensure that Huzhong monitoring station or Hudong monitoring station meet water quality standards. However, considerable load reduction cannot guarantee water quality if there was no water diversion. Water quality of three monitoring stations would be improved a lot under 20 and 30 million m³ annual water diversion scenario. Finally, based on the analyses above, suggestion of focused pollution control project was given for each sub-watershed and an evaluation of one bean product wastewater treatment extension project was given to illustrate how to combine micro and macro aspects in OOPD.

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Key Processes and Mechanisms of Nitrogen and Phosphorus Cycling in Lakes
WU Zhen, WU Sifeng, LIU Yong, ZHANG Yuyu, XIE Shuguang, GUO Huaicheng
Acta Scientiarum Naturalium Universitatis Pekinensis    2018, 54 (1): 218-228.   DOI: 10.13209/j.0479-8023.2017.143
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Special attention has been paid to three types of processes, that is, source process, removal process and internal cycling. Through the summary of literatures, the mechanisms of typical cycling processes, such as sediment release and denitrification, were discussed. The comparison of contributions of different cycling processes was listed as well. Moreover, the main research approaches of experiment and modeling in this field were well summarized and compared, raising a general framework for the study of nutrients cycling in lakes. With the purpose of looking into the cycling of nutrients, different approaches should be combined together. For example, mechanism models and observation for the mass balance of nutrients, then the microcosmic experiments for the impact factors of cycling processes. It is an efficient way to explore the cycling of nutrients in lakes.

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Selection of Ecological Footprint Prediction Model: A Case Study of Wuhan City
LIU Yongchao;GUO Huaicheng;DAI Chao
Acta Scientiarum Naturalium Universitatis Pekinensis    2015, 51 (5): 897-904.  
Abstract610)      PDF(pc) (681KB)(491)       Save
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An Integrated CA-Markov Model for Dynamic Simulation of Land Use Change in Lake Dianchi Watershed
HE Dan,ZHOU Jing,GAO Wei,GUO Huaicheng,YU Shuxia,LIU Yong
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract755)      PDF(pc) (4389KB)(692)       Save
Taking Lake Dianchi Watershed as study area, the dynamics change degree of land use types in the watershed was analyzed based on interpretation data from TM image in 1990 and 1999. The direction of land use conversion was quantitatively analyzed by land use transfer matrix based on the Markov model. Meanwhile, land use change tendency of 2008 was simulated and forecasted based on land use conversion rules using multi-criteria evaluation method from GIS and combining with CA-Markov model. Compared with the interpretation data of 2008, Kappa coefficient of the simulated results was 0.7338, indicating that the simulated results were credible. The spatial patterns of land use change in 2017 and 2026 were simulated by using CA-Markov model. The results show that land use change is also active in this watershed and ecological restoration and reconstruction is still confronted with pressure. Farmland, forest, water and unused land will reduce from 2008 to 2026, while the grassland and construction land will continue to increase. Compared with the trend of land use from 1990 to 2008, the simulated result indicate that farmland, forest and construction land from 2008 to 2026 will keep the same change trend while grassland, water and unused land show the opposite change trend. Construction land will expand on the basis of the present and the change of water is little. Although forest resources will decrease in future, it is still the main land use types in watershed. Construction land expansion significantly increases the load of non-point source pollution in Dianchi. Unreasonable land use is one of the major causes of the water quality degradation in Dianchi Lake currently, and it is going to increase the pressure on the water environment and ecology of water basin in the future. Therefore, to maintain enough arable land per capita, lower fertilization strength, improve land utilization levels, keep a sufficient amount of ecological land, use construction land frugally and intensively, are some important measures to reduce the potential of non-point source pollution in the area. The research can provide scientific support for rational planning and management of land use, the policies formulating of ecological restoration and economic development.
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Identifying the Influence of Water Chemistry on Chlorophyll a in Lake Dianchi: A Structural Equation Modeling Analysis
YAN Xiaopin,LI Yuzhao,LIU Yong,YANG Yonghui,ZHAO Lei,GUO Huaicheng
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract752)      PDF(pc) (644KB)(646)       Save
An integrated approach of absolute principle components score-multivariate linear regression (APCS-MLR) and structural equation modeling (SEM) were developed to understand the influence of water chemistry variables on chlorophyll a (Chl a) in Lake Dianchi. The SEM result was further validated with the artificial neural networks (ANN) model. It proved that there was a good agreement on the results of the various models. The model results demonstrated that, among the water chemistry factors, physical factors (T > DO > SD > pH) had the greatest influence on Chl a; whereas nutrients had little influence. In severely polluted water with chronically high nitrogen (N) and phosphorus (P) concentrations like Lake Dianchi, the change of nutrients concentrations will not significantly influence on Chl a, while the sensibility of N is higher than P. Therefore, nitrogen load reduction should be put in priority for eutrophication control in Lake Dianchi.
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Effects of Long-Term Addition of Lead on the Physical and Chemical Properties and Performance of Aerobic Granules Sludge
LIU Yong,HAN Peng,XU Nan
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract593)      PDF(pc) (2073KB)(246)       Save
The research mainly focused on effects of long-term addition of lead on performance by physicochemical index and stability of aerobic granules sludge system. Results show that removal of phosphorus was affected significantly when the theoretical concentration of lead was 10 mg/L, and the removal efficiency decreased from 50% to 28%. When the concentration of lead had a further increasing, the phosphorus removal rate declined further, and finally maintained at about 18%. Removal efficiency of NH4-N began to decline when the theoretical concentration of lead was up to 50 mg/L, and finally maintained at about 80%. At the same time, the MLSS decreased, SV30 increased, SVI rose sharply, aerobic granular disintegrated gradually and settling charac- teristics deteriorated; but removal of COD increased from 87% to 93% within the range of 1?50 mg/L.
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A DPSIR-Based Indicator System for Ecological Security Assessment at the Basin Scale
LI Yuzhao,LIU Yong,YAN Xiaopin
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract1112)      PDF(pc) (557KB)(1051)       Save
The DPSIR model was modified to meet the urgent decision making requirements on restoring the impaired basins under human’s disturbance. From the point of improved DPSIR model, an indicator system reflecting the panoramic view of ecological security for basin-scale assessment was established. This system has successfully revealed a causal chain of how social-economic behaviors as a driving force could make a pressure to ecological security so as to change its state and how such changes would affect human activities thus lead to a series of “response” measures. Given the specific environment of River Jinsha basin into consideration, an indicator system of 59 indicators i.e. per capital GDP, soil erosion ratio, forest coverage rate etceteraly was established to verify the applicability and importance of improved DPSIR model in basin-scale ecological security assessment. It is believed that the improved DPSIR model is of great value to provide scientific support and practical basis for basin-scale ecological assessment.
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Sensitivity of Risk Explicit Interval Linear Programming (REILP) Solutions to Constraint Risk Preferences: Numerical Analysis and Implications
CHEN Xing,ZOU Rui,LIU Yong,SHENG Hu,GUO Huaicheng
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract831)      PDF(pc) (832KB)(284)       Save
The authors study the solution robustness of the Risk Explicit Interval Linear Programming (REILP) model using numerical experimentations, investigating whether optimal solutions of a REILP would vary under various preferences to different constraints. The first numerical experiment deals with an optimal land use planning subject to nutrient loading constraints. The second one deals with an optimal water resource allocation subject to pollutant loading constraints. The results show that REILP solutions have different sensitivities to constraint preferences in different cases. This phenomenon suggests that in practice it is necessary to conduct thorough analysis on the robustness of REILP solutions to constraint preferences before reaching reliable decision support. In addition, the variability of REILP solutions with regard to various constraint preferences makes it possible to efficiently generate alternative management schemes within the frame work of REILP.
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Key Components and Modeling Framework for Intelligent Watershed Management (IWM)
ZOU Rui,LIU Yong,YAN Xiaopin,GUO Huaicheng
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract770)      PDF(pc) (481KB)(192)       Save
A new watershed management module, Intelligent Watershed Management (IWM), was proposed. The decision need for watershed management was analyzed before the conception and components of IWM were formulated. The idea of IWM comes from the principles of bionics and imitates the process of human decisions. The IWM is significantly differing from traditional watershed management, which includes three main steps, i.e. watershed information inquiring, input-output response modeling at the watershed scale, and optimized decision making. Four key issues of IWM were identified, including the management goal, suitable models, non-linear responses and computational requirement, and the uncertainties in the watershed system. The modeling framework of IWM was developed and some new algorithms were proposed, such as Risk Explicit Interval Linear Programming (REILP) and Nonlinearity-Interval Mapping Scheme (NIMS) for simulation-optimization analysis. Some cases were demonstrated for the efficiency of the proposed models.
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An Integrated Methodology Framework for Cumulative Environmental Assessment of Regional Development Plan
DU Xiaoshang,LIU Yong,GUO Huaicheng,LIU Hui,YANG Pingjian,YANG Yonghui
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract746)            Save
An integrated methodology framework was proposed to acknowledge the important role of cumulative environmental assessment (CEA) in the strategic environmental assessment of regional development plan (RDP). The developed CEA framework consisted of nine steps, including (a) analysis of regional development plan, (b) identification of environmental responses, (c) determination of CEA scales, (d) network analysis of pressures and responses, (e)baselines for CEA, (f) scenarios development, (g) cumulative assessment and early warning, (h) mitigative measures of environmental consequences, and (i) adaptive management. Scenario analysis and system dynamic (SD) models were integrated to deal with the uncertainties and dynamics in the RDP system. The cumulative environmental consequences at various temporal and spatial scales were assessed using the integrated models. The RDP of Zhengzhou Airport Zone (ZZAZ) was taken as a case and its CEA and early warning for regional air and ground water was carried out. Four scenarios were proposed after the comprehensive of ZZAZ’s RDP and the identification of environmental consequences. System dynamic model was developed for temporal and spatial CEA, combined with air and water mechanistic models. Several strategies were proposed based on CEA results to mitigate the consequences, including (a) adjustment of spatial ecological patterns at regional scale, (b) optimization of regional industries structure, (c) pollution control, and (d) adaptive management.
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Research on GRAPES Singular Vectors and Application to Heavy Rain Ensemble Prediction
LIU Yongzhu,YANG Xuesheng,WANG Hongqing
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract1255)            Save
In order to generate the good initial perturbations of ensemble prediction and use limited ensemble members to simulate the time evolution of the atmosphere probability density function in the phase space, the singular vectors (SVs) method was introduced into non-hydrostatic GRAPES meso-scale model. The basic problem of GRAEPS SVs and the method to construct ensemble members based on SVs were researched. GRAPES SVs were solved for a heavy rainfall case by a southwest China vortex moving on July 2008, and an ensemble simulation experiment was made based on GRAPES SVs. The results indicate that the first 27 GRAPES SVs reflect the key information of analysis error; the root mean square error ( RMSE) of ensemble mean about forecast elements have better forecast skills than control forecast, and its ensemble spread is gradually growth with time evolution, reflecting the key information of forecast error; brier score and ROC skill of rainfall show that this ensemble prediction has higher probability skill, and can provide some guidance for the heavy rainfall forecast.
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Characteristics of Heavy Metals Discharge from Industrial Pollution Sources in Shenzhen
LIU Yongwei,MAO Xiaoling,SUN Liying,NI Jinren
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract728)            Save
Taking Shenzhen City as a case study, Equal Standard Pollution Load Index and Equal Standard Pollution Load per Product were used to analyze the characteristics of heavy metals discharge from industrial pollution sources, including pollutant species, temporal-spatial distribution, and industrial contribution. The comparison analysis between 1996 and 2007 was made to examine the characteristics of heavy metals discharged in the recent ten years. The results exhibit as follows: 1) The ranking of average heavy-metal equal standard pollution load was given in the order from large to small as Cr( Ⅵ) , Cd, Pb, Hg and As over the last decade. 2) The amount of heavy-metal discharge increased whereas the amount of heavy metals per product decreased from 1986 to 2007. 3) Compared with other administrative districts and river basins, Longgang District and Pingshan River Basin occupied the highest proportions of pollution load and pollution load per product in 1996, whereas Futian District and Shenzhen River Basin were the highest in 2007. 4) Electronic & Communicating Equipment Manufacturing( ECEM) Industry and Metal Product Manufacturing (MPM) Industry were the top two industries with the maximum pollution load and pollution load per product in 1996 and 2007. The results indicate that Cr( Ⅵ) is the priority pollutants and efforts should be fixed on the ECEM and MPM industry.
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Driving Mechanism of Human Forces to Urban Ecological Water Requirementsin Bao’an, Shenzhen
MAO Xiaoling,TIAN Kun,LI Jingping,LI Tianhong,LIU Yongwei
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract495)            Save
The interruption of human with the urban ecosystems will change the land use structure dramatically and result in deterioration of environmental quality as well as the remarkable change of ecological water requirements. Based on the case study of Bao’an, Shenzhen, this paper presents the quantitative relationship between urban ecological water requirements (UEWR) and the characteristic index for land use structure (SI). The driving mechanism of human activitiesto the land use change and UEWR is studied by Partial Least Squares Regression model. The estimation results indicate the significant negative correlation between UEWR and SI. The human driving forces can explain 50 % ~90 % of the deviation of the land use, especially more than 90 % of the urban construction area and SI. The explanation ability of the same driving forces to the ecological water requirements are 60 % ~80 %. The coefficients of the regression model represent the weight of the driving forces, among which the population is of the most important contribution. Through the same human driving mechanism, the UEWR can be explained and predicted by the simple index of SI.
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Analysis of Long-Term Flood Impact on Sustainability
SUN Liying,MAO Xiaoling,HUANG Zheng,LIU Yongwei
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract689)            Save
A newindex of long-termflood impact on sustainability (LFIS) was proposed, considering the multiple impact of flood on the complex social-economic-environmental system. This index extended the current economic loss basedflood risk analysis into a more comprehensive perspective. Rapid assessment approach was applied for the evaluation and ranking of LFIS using 2359 counties/cities of mainland China as mapping units. The mainland China was zonedinto five kinds of regions, classified in terms of different grades of LFIS, i.e. very high, high, medium, low and very low. The spatial characteristics of LFIS were discussed for regional, provincial and urban levels. The results are helpful for the decision-making of integrated sustainable flood prevention, mitigation and recovery.
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Driving Mechanism of Human Forces to Urban Ecological Water Requirementsin Bao’an, Shenzhen
MAO Xiaoling,TIAN Kun,LI Jingping,LI Tianhong,LIU Yongwei
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract461)            Save
The interruption of human with the urban ecosystems will change the land use structure dramatically and result in deterioration of environmental quality as well as the remarkable change of ecological water requirements. Based on the case study of Bao’an, Shenzhen, this paper presents the quantitative relationship between urban ecological water requirements (UEWR) and the characteristic index for land use structure (SI). The driving mechanism of human activitiesto the land use change and UEWR is studied by Partial Least Squares Regression model. The estimation results indicate the significant negative correlation between UEWR and SI. The human driving forces can explain 50 % ~90 % of the deviation of the land use, especially more than 90 % of the urban construction area and SI. The explanation ability of the same driving forces to the ecological water requirements are 60 % ~80 %. The coefficients of the regression model represent the weight of the driving forces, among which the population is of the most important contribution. Through the same human driving mechanism, the UEWR can be explained and predicted by the simple index of SI.
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Regional Responses of Sustainable Development to Flood Hazards
SUN Liying,HUANG Zheng,LIU Yongwei,NI Jinren
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract658)            Save
Rapid assessment approach is applied to the flood hazard and sustainable development in China based on specified multi-layer indicator systems using county level administrative region as mapping units. According to the interrelationships of flood hazard and sustainable development index, a new classification system is used to map China into four regions. The regional differences of the flood hazard impacts on the sustainable development in these four zones are discussed. Moreover, each zone is further classified into several sub-zones. The characteristics of major and typical counties (cities) are further discussed based on statistics of counties (cities) in different sub-zones.
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Optimize Cryptographic Symmetric Primitives Performance
LIU Yong,CHEN Yu,CHEN Zhong
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract605)            Save
How to optimize AES-128, SHA-256, SHA-512 and Whirlpool algorithms on Loongson-2E is discussed The corresponding optimize techniques are raised for the four algorithms, and the optimized results are analyzed The programs are, to the best knowledge, the fastest implementations on Loongson-2E This paper also proposed several new instructions for speedup symmetric primitives and a parallel hash function mode
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Application of Artificial Neural Ntwork in Urban Fringe's Sustainable Development Index Series
YU Yajuan,WANG Zhen,GUO Huaicheng,HUANG Kai,WANG Shutong,LIU Yong
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract742)            Save
Deriving from the Pressure-State-Response (PSR) theory, a framework of sustainable development (SD) indicators describing urban fringe's urbanization process was brought forward. Sustainable Development Index (ISD) series for multi-years were used to measure the regional capability of sustainability. The socio-economic-environmental grand system was considered as a grey system and artificial neural network (ANN) was applied to calculate the ISD series. Then a case study of Huiji District, Zhengzhou City was adopted for ISD assessment from the year 1987 to 2004, and uncertainty analysis was also construed. The results showed that both the framework and the ISD with ANN were suitable in reflecting its SD levels. The method is recommendable for analogous problems.
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