Z.F. Yang

Beijing Normal University, Peping, Beijing, China

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Publications (202)262.43 Total impact

  • Y. Liu · Y.P. Cai · Z.F. Yang · Q. Tan · X. Lin
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    ABSTRACT: In this research, an inexact two-stage chance-constrained programming model (ITSCCP) was developed for supporting the planning of coupled coal and power management systems in China based on the integration of multiple programming methods and China’s special coal-pricing mechanism. Multiple uncertainties that were expressed as interval numbers and probability density functions could be effectively tackled. Recourse decisions for power generation with a certain level of economic penalties could be identified to evaluate economic penalties associated with violation of original coal-pricing contracts between coal suppliers and power plants. Also, risks associated with the violation of coal transportation capacities were quantified and analyzed. The developed ITSCCP was applied to a case of long-term management of coal and power in north China. Interval solutions associated with different risk levels of transportation-supply constraint violations under varying power-generation demands were obtained. The solutions indicated that they could be used for generating decision alternatives and helping decision makers identify desired strategies under multiple social-economic, environmental and system-reliability constraints. Moreover, ITSCCP could not only provide in-depth analysis of various policy scenarios associated with different levels of economic penalties when the promised targets were violated, but also identify optimal solutions under the existing government-guided coal-pricing mechanism.
    No preview · Article · Jul 2016 · International Journal of Electrical Power & Energy Systems
  • X. A. Yin · G. E. Petts · Z. F. Yang
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    ABSTRACT: The third biennial symposium of the International Society for River Science was held at Beijing Normal University, China, on 5–9 August 2013. The symposium was dedicated to consolidating knowledge on riverine ecosystem in response to the impacts of ever-increasing environmental pressures and promoting multi-disciplinary solutions for protecting and restoring ecosystems. Nine papers were selected to illustrate advances in understanding the mechanisms of ecological degradation, promoting new models for simulating the hydrological and ecological processes and establishing new tools for ecofriendly water resources management. Copyright © 2015 John Wiley & Sons, Ltd.
    No preview · Article · May 2015 · River Research and Applications
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    Z. F. Yang · Y. P. Cai

    Preview · Article · Sep 2014 · Hydrology and Earth System Sciences
  • D.Y. Miao · W.W. Huang · Y.P. Li · Z.F. Yang
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    ABSTRACT: This study presents an interval-fuzzy De Novo programming (IFDNP) method for planning water-resourcesmanagement systems under uncertainty. IFDNP is derived by incorporating the concepts of interval parameters and fuzzy sets within a De Novo programming framework. IFDNP has the advantages in constructing optimal system design through introducing the flexibility into the available resources in the model’s constraints. Moreover, IFDNP allows the decision makers to achieve a metaoptimal system performance and improve the performance of compromise solutions, and it is effective for dealing with the system design problems involving multiple objectives and multiple uncertainties. The IFDNP is then applied to a case study of designing an inexact optimal system with budget limit for water resources management and planning. Various scenarios that are associated with different levels of economic implication consequences and water allocation patterns under uncertainty are analyzed. Results can help decision makers to evaluate alternatives of system designs and to determine which of these designs can most efficiently achieve the desired economic objective constrained by limited resources.
    No preview · Article · Sep 2014 · Journal of Environmental Informatics
  • X. A. Yin · Z. F. Yang · G. E. Petts
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    ABSTRACT: Assessing alterations of a river's flow regime provides the basis for river protection and restoration planning. The range of variation approach (RVA) is a commonly used method to evaluate alterations in a river's flow regime. However, RVA underestimates the degree of flow regime alteration potentially, because it only considers the difference in frequency between the pre-impact and post-impact hydrologic indicator values within certain target ranges and does not consider alteration of the order of hydrologic year types (HYTs; i.e. wet, average and dry years). The HYT order is an important holistic feature of the flow regime. The human-induced change of HYTs, such as from a dry year to a wet year or from an average year to a dry year, can be a major cause of ecosystem alteration. For some species, the order of the HYTs was more important than single-year events (such as the flood magnitude during a given year). To address this problem with the RVA, we proposed a modification of this method that accounts for alteration of the order of HYTs. We developed a metric for assessing the alteration of the HYT order based on Euclidean distance and then combined this metric with the RVA. We applied the revised method to a case study of the Sha River in northern China to test its effectiveness. The results demonstrated that the new method solved RVA's problem of potentially underestimating the degree of flow regime alteration and enabled a more comprehensive analysis of the alteration of the flow regime. Copyright © 2014 John Wiley & Sons, Ltd.
    No preview · Article · Aug 2014 · River Research and Applications
  • X. A. Yin · Z. F. Yang · C. L. Liu
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    ABSTRACT: In deregulated electricity markets, hydropower portfolio design has become an essential task for producers. The previous research on hydropower portfolio optimisation focused mainly on the maximisation of profits but did not take into account riverine ecosystem protection. Although profit maximisation is the major objective for producers in deregulated markets, protection of riverine ecosystems must be incorporated into the process of hydropower portfolio optimisation, especially against a background of increasing attention to environmental protection and stronger opposition to hydropower generation. This research seeks mainly to remind hydropower producers of the requirement of river protection when they design portfolios and help shift portfolio optimisation from economically oriented to ecologically friendly. We establish a framework to determine the optimal portfolio for a hydropower reservoir, accounting for both economic benefits and ecological needs. In this framework, the degree of natural flow regime alteration is adopted as a constraint on hydropower generation to protect riverine ecosystems, and the maximisation of mean annual revenue is set as the optimisation objective. The electricity volumes assigned in different electricity submarkets are optimised by the noisy genetic algorithm. The proposed framework is applied to China's Wangkuai Reservoir to test its effectiveness. The results show that the new framework could help to design eco-friendly portfolios that can ensure a planned profit and reduce alteration of the natural flow regime.
    No preview · Article · Mar 2014 · Hydrology and Earth System Sciences Discussions
  • D. Y. Miao · Y. P. Li · G. H. Huang · Z. F. Yang · C. H. Li
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    ABSTRACT: This study proposes an interval semiinfinite De Novo programming (ISIDP) method for the planning of water resource management systems under uncertainty. The ISIDP problem is settled by dividing it into two interactive linear programming subproblems and solving it by using a conventional simplex method. To evaluate the applicability of the proposed model, the method is applied to a case study of the Yuecheng Reservoir in Zhangweinan River Basin, China. The results indicate that the strategies generated through ISIDP would not increase the complexity in decision-making processes. Compared with the conventional optimization method, ISIDP has the advantages of (1)better reflecting the association of the system benefits with water price, (2)generating more reliable solutions with a lower risk of system failure as a result of the possible violation of constraints, and (3)providing more flexible management planning because the availability of budgets can be adjusted with the variations in water price.
    No preview · Article · Feb 2014 · Journal of Water Resources Planning and Management
  • M.R. Su · Z.F. Yang · B. Chen
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    ABSTRACT: Set Pair Analysis (SPA) is used to assess the urban ecosystem health in this paper. With this uncertainty assessment method, urban ecosystem health indices can be integrated to evaluate the relative approximate degree of real index set to the optimal one, which can be used to describe the health state of the urban ecosystems. In addition, the ecosystem health states of some typical cities in China from 1997 to 2005 are evaluated based on SPA. Comparisons among ecosystem healthy levels of the typical cities reveal that part of them remains well and the rest varies over time. It is therefore concluded that the SPA can serve as an effective assessment tool to compare different ecosystem healthy levels of urban areas.
    No preview · Article · Jan 2014
  • G.Y. Liu · Z.F. Yang · B. Chen
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    ABSTRACT: The objective of this study is to measure and evaluate the healthy levels of urban ecosystems, employing an indices framework and a novel emergy-based index. Characteristics and comparative implications of the temporal variation of the urban ecosystem healthy levels are also outlined. Considering four factors including vigor (V), organizational structure (O), resilience (R) and function maintenance (F), emergy-based urban ecosystem health index (EUEHI) is established and employed to measure and evaluate the relative healthy levels among various ecosystems of Beijing, Shanghai, Tianjin and Chongqing as the typical Chinese cities. It is found that the integrated index of urban ecosystem health of these four cities followed as the sequence: Chongqing Beijing> Shanghai>Tianjin. In addition, linking up with the single-factor analysis, it shows that the key factors of urban ecosystem health are the promotion of urban metabolism function for an increased vigor, the protection of natural ecosystem for organizational structure, the decrease of socioeconomic development pressure for a maintaining resilience, and the derive of benefits for a continual function maintenance.
    No preview · Article · Jan 2014
  • X.S. Zhao · Z.F. Yang · B.S. Cui · T. Sun
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    ABSTRACT: Structure and function (e.g. strip distribution of the vegetation fashion) are determined by the gradient environment alternation influenced by the freshwater inflow and tide in estuarine systems. Freshwater inflows, such as upriver periodical floods are significant for maintaining the community structure of freshwater wetland and halophytic wetland vegetation in the Yellow River Estuary of China. However, Yellow River flow has been decreasing for several decades and duration of the dry periods has been steadily increasing since 1987. Area of the freshwater vegetation and freshwater marshlands decreases continuously. For the purpose of regeneration of the reduced fresh water swamp, ecological restoration project has been carried out by State Forest Bureau of China since 2002. It was about 2.0×108m3 of freshwater been supplied into the freshwater swamp each year. Based on the series data from 30 quadrats for 6 years in the study area, the effects of the ecological restoration project to freshwater marshlands vegetation and soil salt content were conducted. It is indicated that: (1) vegetation species abundance increased from 6 to 23, average coverage increased from 8% to 35%, community types increased from 3 to 6 analyzed by TWINSPAN; (2) after restoration, soil salt content, soil Na+, Cl-, Mg2+, Ca2+, K+ content and pH value reduced significantly, and soil moisture content increased significantly, for all quadrats, P-value < 0.05 based on ANOVA analysis. The ecological restoration project had a positive effect on freshwater marshlands restoration, which was valuable to be imitated for the ecological restoration of other seashore freshwater marshlands.
    No preview · Article · Jan 2014
  • Z.F. Yang · Y.W. Zhao
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    ABSTRACT: Urban river restoration has seized the attention of many researchers and decision-makers due to the seriously degraded urban river worldwide. Directed by the ecosystem theory and oriented to the coordination of human and urban water system, the connotation of urban river restoration planning is outlined as a reasonable scheme for the maintenance of river health and resistance against disturbances in certain spatial and temporal scales. After the boundary of urban river restoration planning is defined, a 3-step planning procedure, including degradation factor identification, restoration target validation and restoration scheme formulation, is thereby proposed. The key points of the urban river restoration embracing the river health diagnosis, restoration target and indicator system construction, river ecological trend prediction and river restoration scheme optimization are illustrated in detail. Finally, a case study of Zhongda River in Ningbo city is presented to verify the practicability of the proposed river restoration planning framework.
    No preview · Article · Jan 2014
  • Y.Y. Lv · T. Yu · Z.F. Yang · Q.Y. Hou · B.Y. Ji · Y.F. Zhang · L.X. Jin
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    ABSTRACT: Export Date: 18 October 2014
    No preview · Conference Paper · Jan 2014
  • R. Zhao · T. Sun · Z.F. Yang · Z.Y. Shen
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    ABSTRACT: The impacts of changing freshwater inflow on the estuarine ecosystem are assessed by quantifying the environmental flows for the habitat in the Yangtze Estuary of China. Two main steps are involved in determining the environmental flows for the habitat, the first step is identifying of the ecological objectives and the second one is determining the relations between the ecological objectives and the freshwater inflow. The Environmental flows satisfy the requirements of the salinity gradient for the critical habitat of Chinese sturgeon (Acipenser sinensis), which is the first-grade state protection wildlife. The salinity objective which fulfilling the requirements of the Acipenser sinensis in the critical period of the year is considered as the ecological objective for the habitat. A salinity-river flows response model, combining a hydrodynamic model with a salinity model, is setup to simulate the spatial distribution of salinity with the variation of the freshwater inflow. The results indicated that the environmental flows are 919.1×109, 705.9×109 and 593.3×109m3 in the whole year for different levels of ecological objectives, respectively, which is equal to 97%, 75% and 63% of the annual river discharge for the Yangtze Estuary. By comparison between the environmental flows and river discharge, it is concluded that the annual natural flow regime can satisfy the environmental flows for the habitat. However, the temporal variation of river flows has distinct difference from the environmental flows for the habitat in critical periods (May, July & August).
    No preview · Article · Jan 2014
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    Z. H. Xu · X. A. Yin · Z. F. Yang
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    ABSTRACT: Lake eutrophication is a serious global environmental issue. Phytoremediation is a promising, cost-effective, and environmentally friendly technology for water quality restoration. However, besides nutrient removal, macrophytes also deeply affect the hydrologic cycle of lake system through evapotranspiration. Changes in hydrologic cycle caused by macrophytes have a great influence on lake water quality restoration. As a result of the two opposite effects of macrophytes on water quality restoration (i.e. an increase in macrophytes can increase nutrient removal and improve water quality while also increasing evapotranspiration, reducing water volume and consequently decreasing water quality), rational macrophyte control through planting and harvest is very important. In this study, a new approach is proposed to optimise the initial planting area and monthly harvest scheme of macrophytes for water quality restoration. The month-by-month effects of macrophyte management on lake water quality are considered. Baiyangdian Lake serves as a case study, using the common reed. It was found that water quality was closest to Grade III on the Chinese water quality scale when the reed planting area was 123 km2 (40% of the lake surface area) and most reeds would be harvested at the end of June. The optimisation approach proposed in this study will be a useful reference for lake restoration.
    Full-text · Article · Dec 2013 · Hydrology and Earth System Sciences
  • Z. F. Yang · T. Sun · R. Zhao
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    ABSTRACT: We developed an approach to assess environmental flows in estuaries related to preference of phytoplankton considering the complex relationship between hydrological modification and biomass in ecosystems. As a first step, a relationship was established between biomass requirements for organisms of primary and higher nutritional levels based on the principle of nutritional energy flow of ecosystem. Then, diagnostic pigments were employed to represent phytoplankton community biomass, which indicated competition between two groups of phytoplankton in the biochemistry process. Considering empirical relationships between diagnostic pigments and critical environmental factors, responses of biomass to river discharges were established based on a convection-diffusion model by simulating distributions of critical environmental factors under action of river discharges and tide currents. Consequently, environmental flows could be recommended for different requirements of fish biomass. In the case study in the Yellow River estuary, May and October were identified as critical months for fish reproduction and growth during dry years. Artificial hydrological regulation strategies should carefully consider the temporal variations of natural flow regime, especially for a high-amplitude flood pulse, which may cause negative effects on phytoplankton groups and higher organism biomass.
    No preview · Article · Dec 2013 · Hydrology and Earth System Sciences
  • L. J. Zhang · X. A. Yin · Y. Zhi · Z. F. Yang
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    ABSTRACT: China is a water-stressed country, and agriculture consumes the bulk of its water resources. Assessing the virtual water content (VWC) of crops is one important way to develop efficient water management measures to alleviate water resources conflicts among different sectors. In this research, the VWC of rice, as a major crop in China, was assessed and the spatial characteristics were analyzed. In addition to the calculation of green, blue and grey water - the direct water in VWC - the indirect water use of rice was also calculated, using the Input-Output model. The percentages of direct green, blue, grey and indirect water in the total VWC of rice in China were 43.8, 28.2, 27.6, and 0.4%. The total VWC of rice generally showed a three-tiered distribution, and decreased from southeast to northwest. The higher values of direct green water of rice were mainly concentrated in Southeast and Southwest China, while these values were relatively low in Northwest China and Inner Mongolia. The higher direct blue water values were mainly concentrated in the eastern and southern coastal regions and Northwest China, and low values were mainly concentrated in Southwest China. Grey water values were relatively high in Shanxi and Guangxi provinces and low in Northeast and Northwest China. The regions with high values for indirect water were randomly distributed but the regions with low values were mainly concentrated in Northwest and Southwest China. For the regions with relatively high total VWC the high values of blue water made the largest contribution, although for the country as a whole the direct green water is the most important contributor.
    No preview · Article · Dec 2013 · Hydrology and Earth System Sciences Discussions
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    Y. Zhi · Z. F. Yang · X. A. Yin
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    ABSTRACT: Decomposition analysis of water footprint (WF) changes, or assessing the changes in WF and identifying the contributions of factors leading to the changes, is important to water resource management. However, conventional studies focus on WF from the perspective of administrative region rather than river basin. Decomposition analysis of WF changes from the perspective of the river basin is more scientific. To address this perspective, we built a framework in which the input-output (IO) model and the Structural Decomposition Analysis (SDA) model for WF could be implemented in a river basin by computing IO data for the river basin with the Generating Regional IO Tables (GRIT) method. This framework is illustrated in the Haihe River Basin (HRB), which is a typical water-limited river basin. It shows that the total WF in the HRB increased from 4.3 × 1010 m3 in 2002 to 5.6 × 1010 m3 in 2007, and the agriculture sector makes the dominant contribution to the increase. Both the WF of domestic products (internal) and the WF of imported products (external) increased, and the proportion of external WF rose from 29.1% to 34.4%. The technological effect was the dominant contributor to offsetting the increase of WF; however, the growth of WF caused by the economic structural effect and the scale effect was greater, so the total WF increased. This study provides insights about water challenges in the HRB and proposes possible strategies for the future, and serves as a reference for WF management and policy making in other water-limited river basins.
    Preview · Article · Dec 2013 · Hydrology and Earth System Sciences Discussions
  • Y. Zhang · Z.-F. Yang · W. Wang · C.-Z. Li · Y.-M. Liu · H.-W. Wang
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    ABSTRACT: Objective: To observe the heart rate variability (HRV) at admission and before treatment in patients with myocardial infarction. Methods: Electrocardiograms were recorded from healthy people, patients with coronary heart disease, patients with acute myocardial infarction and acute experimental ischemia animals, and short-time HRV analysis was performed. Results: Except for the heart rate, the other indexes of HRV in patients with acute myocardial infarction were significantly higher than those in healthy people, and SDNN (standard deviation of normal to normal RR intervals, representative of sympathetic tone), SD of delta NN (standard deviation of successive differences between adjacent normal cycles), NN50 (the percent of time that the difference between adjacent normal RR intervals was greater than 50 ms) and minor axis of poincare plot (SD1) which stood for parasympathetic tone, increased by 1.8, 2.7, 7.5 and 3.1 times respectively compared with healthy people. Those changes were also observed in the animal model with acute myocardial ischemia evoked by hypophysin. In comparison with healthy people, the HRV indexes of patients with coronary heart disease decreased substantially, although SDNN and SD of delta NN did not change significantly (P>0.05), SD1 decreased significantly (P<0.01). Conclusion: HRV indexes in patients with acute myocardial infarction would elevate significantly. Compared with healthy people, on the other hand, the patients with chronic coronary heart disease exhibit decreased HRV indexes. In all probability, SD1 is more useful in evaluation of the changes in autonomic nervous activities than the other HRV indexes.
    No preview · Article · Jul 2013 · Journal of Shanghai Jiaotong University (Medical Science)
  • A.-J. Li · X.-Y. Li · X.-C. Quan · Z.-F. Yang
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    ABSTRACT: Partial nitrification for the biological nitrogen removal (BNR) via nitrite has recently gained interest for treating high-strength ammonium wastewater with low organic matter content. However, stability of partial nitrification is still a challenge in activated sludge system. In the present study, the technique of aerobic granulation was developed to produce granules for stable nitritation, treating ammonia-rich inorganic influent with 400 mg NH4+-N/L. The morphology, physical properties, bacterial community structure and partial nitrification performance of the sludge were characterized throughout the experiments. The results indicated that aerobic granules could be produced for partial nitrification through selective discharge of small and slow-settling sludge flocs. Sludge granulation help to achieve ammonium oxidation to the level of nitritation, or partial nitrification, other than to complete nitrification. Based on DNA-base molecular analysis, aerobic granulation resulted in an enrichment of AOB and a reduction of nitrite-oxidizing bacteria (NOB) in the granular sludge, which is highly favorable to a stable operation of partial nitrification.
    No preview · Article · Jul 2013 · Environmental engineering and management journal
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    Liang Chen · Z.F. Yang · Bin Chen
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    ABSTRACT: Based on the logarithmic mean Divisia index (LMDI) approach, this paper presents a decomposition analysis of China's energy-related industrial CO2 emissions from 1985 to 2007, as well as a comparative analysis of differential influences of various factors on six sectors. Via the decomposition, five categories of influencing factors are included: (1) Per capita GDP (PCG) was the largest positive driving factor for industrial CO2 emissions growth for all sectors in China, with the largest cumulative contribution value; Population (P), economic structure (YS) and energy structure (ES) also played a positive driving role, but with weak contributions. As the only negative inhibiting factor, energy intensity (EI) significantly reduced the energy-related CO2 emissions from industrial sectors. Meanwhile, CO2 emissions reduction based on the efficiency of energy use still held a large space. (2) Various influencing factors imposed differential impacts on CO2 emissions of six sectors.
    Full-text · Article · May 2013 · Energies