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The seasonal cycle (SC) of surface air temperature is a substantial element in climatology. Some basic and important topics in climate change studies are based on accurate and reliable estimation of SCs, such as percentile‐based indices of extremes and probability density function (PDF) changes of daily temperatures. For both of them, most studies characterized SCs using averages of multi‐days windows, which is not smooth and accurate enough representing the extreme thresholds and climatological normal of SCs. It is necessary to construct smooth and reasonable SCs for more accurate estimation of temperature changes on extreme thresholds and PDFs. In this study, we propose a flexible method based on generalized additive models for location scale and shape and penalized b‐spline smoothing technique with respective distributions to construct smooth SCs and SC for extreme temperatures (SCETs). The accuracy of the constructed smooth SCETs is good with the estimation biases of percentiles tending to be zero. The constructed smooth SCET also exhibits good stability over time, such that the magnitude changes of temperatures on each calendar day are close to climatic changes of mean temperature when the concerned period shifts. Based on the constructed smooth SCs, climatic changes by seasons and PDFs between two periods, 1961–1990 and 1991–2020, are examined over China. The increase of thresholds for hot extremes in spring during the recent period is prominent, while the increase of thresholds for daytime cold extremes in summer over a part of central to southern China is also notable. The smooth SCs and SCETs based on our flexible statistical modelling framework can characterize daily extreme temperatures reasonably and accurately, and should be expected to have more applications for a better understanding of climate changes related to distributions and seasonal cycles. [ABSTRACT FROM AUTHOR]

Based on gridded daily precipitation data and the China Meteorological Administration typhoon best-track dataset from 1961 to 2020, this study presents an evaluation of the contribution of typhoons to extreme precipitation in coastal areas of China. Specifically, both mixed and single Metastatistical Extreme Value (MEV) models are devised to evaluate the effects of typhoons on the probability distribution of extreme precipitation amounts. The related influencing factors are explored by correlation tests and four case study watersheds are selected to showcase the effects of typhoons. The results show that typhoons make significant contribution to high-return-period extreme precipitation in coastal and some nearby inland areas of China. The mixed Metastatistical extreme value distribution, which takes into account the distribution of typhoon precipitation, can better formulate the probability of extreme precipitation. The relative errors between the estimated precipitation quantiles of mixed and single MEV tend to be larger in coastal areas than in inland areas, and also be larger in northern coastal areas than in southern sub-regions. Overall, the contribution of typhoons to extreme precipitation and the differences of average precipitation between typhoon-induced and non-typhoon-induced events are important influencing factors on the distribution of the probability of extreme precipitation in coastal areas of China [ABSTRACT FROM AUTHOR]

Multimodule and multisensor data with different characteristics can reflect the overall operating status of the equipment from different angles. It is far from enough to monitor the operating status of equipment from a single perspective for this fails to take all valid information into account. However, data integration may face problems such as the curse of dimensionality and scale mismatches. Therefore, decision fusion, which needs to measure and manage evidence conflicts, has attracted extensive attention from scholars. However, most of the state-of-art methods focus on conflict management based on evidence itself and ignore the irrationality of conflict factor $K$ in measuring conflicts and the reliability of evidence sources in conflict management. In order to solve the above problems, a novel hybrid decision fusion approach is proposed in this article. First, divide data into modules and use the models in the model library to conduct cross-validation, thus obtaining the performance ranking. Then, select the optimal classifier of each module to obtain the evidence for decision fusion. Given the conflict of evidences, the Jensen–Shannon (JS) divergence is used to measure the conflict, and those high-conflict evidences will be revised through sensitivity and support analyses. Finally, the Dempster–Shafer (DS) evidence theory is used to integrate multimodule evidences to assess the status. To prove the feasibility and effectiveness of this approach, a realistic operational shield case in China is used. [ABSTRACT FROM AUTHOR]

Rockfall is a significant geological hazard in the mountain areas of Western China, which causes damage to residential and infrastructures. Velocity analysis of rock impacts on the cushion layers is a powerful method to predict the effectiveness of a protective cushion. Thus, this study investigates the velocity, angle, and angular velocity of rockfall after collision, considering the cushion layer's statistical nature, different slope angles, and collision positions. A stochastic collision model of the rockfall–cushion layer is established in this study to understand the mechanism of the collision process. Impulse and impulse moment theorems form the basis for the analytical solution of the velocity after the collision. The results show that the radius ratio of rockfall and cushion particle and slope angle are essential for rockfall–cushion layer collision. The probability distributions of rebound velocity, rebound angle, and rebound angular velocity follow the Gaussian distribution based on probability theory. When the radius ratio of rockfall and cushion particle is larger than the critical radius ratio Rcr, the radius ratio of rockfall and cushion particle no longer affects the collision process. The mean and standard deviation of rebound velocity, rebound angle, and rebound angular velocity after collision are fitted as the radius ratio of rockfall and cushion particle and slope angle functions, respectively. Therefore, it cannot ignore the influence of the radius ratio of rockfall and cushion particle, slope angle, and microstructure of slope surfaces in designing protective cushions. [ABSTRACT FROM AUTHOR]

The scientific judgement of the structural abrupt transition characteristics of the carbon market price is an important means to comprehensively analyze its fluctuation law and effectively prevent carbon market risks. However, the existing methods for identifying structural changes of the carbon market based on carbon price data mostly regard the carbon price series as a deterministic time series and pay less attention to the uncertainty implied by the carbon price series. We propose a framework for identifying abrupt transitions in the carbon market from the perspective of a complex network by considering the influence of random factors on the carbon price series, expressing the carbon price series as a sequence of probability density functions, using the distribution of probability density to reveal the uncertainty information implied by carbon price series and constructing a recurrence network of carbon price probability density. Based on the community structure, the break index and statistical test method are defined. The simulation verifies the effectiveness and superiority of the method compared with traditional methods. An empirical analysis uses the carbon price data of the European Union carbon market and seven pilot carbon markets in China. The results show many abrupt transitions in the carbon price series of the two markets, whose occurrence period is closely related to major events. [ABSTRACT FROM AUTHOR]

The manufacturing of rubber bearing is complicated, the horizontal stiffness of the final product maybe greatly affected by the uncertainties during the processing, thus, it is necessary to study the distribution characteristics of the rubber bearings' horizontal stiffness, and its influence on the seismic performance of the isolation structure. The rubber layer thickness was taken as a comprehensive index, measurements were carried out before and after vulcanization, the relationship between the rubber layer thickness and the variation of bearing's horizontal stiffness was deduced, and an optimization method to reduce the variation of bearing stiffness was proposed. Then, based on the equivalent shear stiffness samples of 224 rubber bearings of 3 different specifications produced by two manufacturers, systematic statistical analysis and probability distribution tests were carried out. Result shown that the equivalent shear stiffness obeys the I-type minimum-value distribution. Finally, the influence of the variation of the bearing's stiffness on the seismic performance of the rubber bearing isolation structure was studied. The results shown that the probability distribution form of the rubber bearings stiffness has a certain influence on the adjustment coefficient ψ of the isolation structure, but the damping effect of the isolation structure still has sufficient safety reserve according to China's Code for Seismic Design of Buildings. [ABSTRACT FROM AUTHOR]

Precipitation anomaly grades are usually defined by the percentage anomaly (Pa) or probability distribution (Pd) methods. However, the difference between the two may lead to different estimates for the same events, creating difficulty in judging the severity of the events. Here, we quantify the difference in measuring precipitation variability in China between Pa and Pd methods and analyze physical meaning and influencing factors of the difference. The results show that Pa tends to underestimate the domain of wetness (e.g., it underestimated 7.67% in June 2018) and overestimate/underestimate the severity of extreme wetness (>1.5σ)/dryness (<–1.3σ) compared to the Pd method. Because precipitation has a positive skewed distribution, and precipitation maximum values have a larger influence on Pa than on Pd. On the other hand, uniform Pa thresholds for classifying drought grades at all stations are unreasonable. Because of an asymmetrical range of actual Pa value, Pa fails to symmetrically reflect the degree of drought and flood. Spatially, the large difference usually appears in the areas with extreme precipitation. Therefore, the more extreme precipitation stations, the greater the spatial dispersion of precipitation and the greater the total difference between Pa and Pd in whole China. We further find that the Pa‐Pd difference is significantly related to a concurrent warming of the tropical Indian Ocean and the tropical Pacific sea surface in spring. And the Pa‐Pd difference is rising at 0.022σ/10a with the increase of extreme events associated with the ocean warming, which deserves attention from the decision‐making departments. Plain Language Summary: Frequent extreme weather events have brought huge disasters to human society. A reasonable description of the precipitation situation can help the decision‐making department to reasonably evaluate the disaster levels and make reasonable response plans. There are many methods for evaluating precipitation status, among which percentage anomaly (Pa) and probability distribution (Pd) methods are commonly used. This article quantitatively compares the difference between Pa and Pd in describing the variability of precipitation. And what we find is that the Pa method underestimates the domain of wetness and overestimates the severity of extreme wetness compared to the Pd method. Besides, Pa cannot symmetrically reflect the degree of drought and flood. The same Pa value has different effects at different rainfall stations. Furthermore, a large difference between the two methods usually appears in the areas with extreme precipitation. And the tropical ocean warming has resulted in a larger discrepancy in measuring China precipitation variability in recent years than before. Key Points: Quantifying precipitation difference between percentage anomaly (Pa) and probability distribution (Pd)Pa method underestimate/overestimate the domain of wetness/dryness and overestimate/underestimate the severity of extreme wetness/drynessThe tropical ocean warming has resulted in a larger discrepancy in measuring China precipitation variability than before [ABSTRACT FROM AUTHOR]

The impact of wind speed on PV power generation is influenced by the monsoon and the complex topography and environmental factors found in mountainous areas. This complexity can reduce the correlation between PV power and irradiance. To better understand the impact of wind speed, we conducted an analysis in various topographical regions of the Hengduan Mountain in China. Our findings show that high wind speeds can enhance PV utilization, particularly in plateau and hill regions. This is due to the blocking and lifting effect of the north-south oriented mountains on the east-west wind, as well as the channeling effect on the north-south wind. To improve the efficiency of utilizing solar energy, it is important to consider the spatial distribution of wind speed when developing PV. Correlation analysis of multi-factors on a spatial and temporal scale can also offer insight. Furthermore, planning the layout of PV systems with meteorological resources in mind can enhance PV utilization in complex mountainous terrain. [ABSTRACT FROM AUTHOR]

The North Anhui Province Plain (NAHPP), an important food production plain in China, is prone to frequent droughts and floods. To better understand the extreme events and mitigate their effects, this paper explores the spatiotemporal variation of precipitation extremes in the NAHPP during 1976 and 2018. Variation trends and spatial distributions of the annual maximum 1-day, 3-day, 7-day, and 15-day-rainfall were analyzed, and the probability distribution of rainfall extremes in the NAHPP was calculated by three distribution functions (Gumbel, P-III, and generalized extreme value). The optimal fitting function was selected based on the Kolmogorov–Smirnov test, and the rainfall in different return periods was calculated according to the optimal fitting function. The results indicate that rainfall extreme showed a 2- to 3-year periodicity on the interannual scale and 21-year periodicity on the chronological scale in the NAHPP. The rainfall extremes showed nonsignificant increase trend over the NAHPP, and some stations showed no significant decrease trend. The P-III distribution function best fit to the rainfall extremes (the maximum 1-day rainfall: 59%). The spatial distributions of rainfall extremes were similar in different return periods. As the return period increased, the estimated rainfall by the three distribution functions were slightly larger than that in the empirical return period. The findings will benefit regional water resources management and water-related risk control. [ABSTRACT FROM AUTHOR]

Landsliding is a prominent geomorphological process in both the Loess Plateau and the Qinba Mountains in Central China. The size distribution of landslides plays an important role in quantifying their occurrence and magnitude, estimating erosion and sediment yields, and determining hazards. We generated landslide inventories for six study sites within the two study regions based on results from field surveying and remote sensing analyses. Landside size distribution differs considerably in both regions and can be described by the double Pareto and inverse gamma distributions. The power law decays faster in the Loess Plateau than in the Qinba Mountains; the locations of the rollover occur at larger landslide size in the Loess Plateau. Moreover, α, an exponent of power law scaling related to slope in the double Pareto function, is strongly related to ρ + 1, a control of power law decay in the inverse gamma. This study provides an insight into the landslide size probability distribution in different landscape types. [ABSTRACT FROM AUTHOR]

The probability distributions of hydrological series are primarily determined according to the best fitting of empirical probability from observation data. The fitted distribution functions are variable in different watersheds, and thus difficult to be applied to estimate probability of any discharge occurrence at other stations. In this study, chaotic characteristics of annual discharge series are analyzed by using correlation dimension analysis at 12 hydrological stations in the six main rivers in China. It is found that the correlation integral of annual discharge series represents the probability distribution of difference between any two annual discharges. The derived probability function can be perfectly fitted by the Pearson III function. Although the six basins have distinctively different climate conditions from the northern cold temperature zone to the southern subtropical zone, the correlation dimension of chaotic characteristics for annual discharges are similar at the 12 hydrological stations. The mean of difference between any two annual discharges, the maximum and minimum of annual discharge are found to be high correlation with the mean of annual discharge. Moreover, the derived probability distributions at 12 hydrological stations can be normalized by a universal distribution function, and the derived probability is high correlation with the probability distribution of annual discharge. This universal probability distribution can be easily applied to obtain probability distributions of annual discharge series over any stations. [ABSTRACT FROM AUTHOR]

Rockfall is one of the common geological disasters in China, which causes huge losses to the country and the people. Based on the impulse and impulse moment theorems, and considering the stochastic factors in the process of rolling stone collision, a stochastic collision model of the rockfall-wall is established, and the analytical solution for the velocity of the rolling stone after collision is obtained. When considering the initial rotation of the rolling stone, the predicted result from the model agrees with the experimental result, and when the initial rotation is ignored, the result obtained from the model will underestimate/overestimate the rebound velocity, and the maximum reaches 20%. Furthermore, the probability distribution and the fit curve for the velocity and trajectory of the rolling stone depends on the project. The result shows that the rebound velocity and angle of the rolling stone follow a typical Gaussian distribution, and the horizontal distance and bounce height follow the Gaussian and exponential distribution, respectively. The prediction of the velocity and trajectory of the rolling stone provides a theoretical basis for the optimal design of engineering structures. [ABSTRACT FROM AUTHOR]

Evaluation of soil redistribution rates and influence on crop yield in agricultural catchments is very important information, which can provide a scientific basis for arrangement of soil and water conservation measures and sustainable crop production. In recent decades, the soil erosion has greatly aggravated in the Mollisol region of Northeast China due to unreasonable land management, which in turn has reduced crop yield. The objectives of this study were to investigate the spatial distribution of soil redistribution and the relationship between crop yield and soil redistribute at a catchment of the Chinese Mollisol region. A total of 176 soil samples were collected based on a 200 m by 200 m grid and 4 yr of corn (Zea mays L.) yields were measured. The 137Cs trace technique and Zhang Xinbao’s mass balance model indicated that the soil redistribution rates ranged from −7122.25 to 5471.70 t km−2 yr−1 and averaged −830.10 t km−2 yr−1. Soil erosion dominated in the research area. The corn yields for four years ranged from 43.24 to 136.19 kg km−2 and averaged 90.42 kg km−2. The spatial distribution of soil redistribution rates and corn yield showed a similar ribbon and plaque characteristics at the catchment. An equation between corn yield and soil redistribution rates was fitted and showed that there was a significant negative correlation between corn yield and soil erosion rates, while there was no relationship between the corn yield and soil deposition rates. Therefore, effective soil and water conservation measures are urgently needed to increase crop yield and realize sustainable land-use management. [ABSTRACT FROM AUTHOR]

There are large amounts of ion-adsorption rare earth resources in the granite red soil region of southern China, and exploitation of rare earth elements (REEs) has caused serious soil erosion and soil pollution in the area. In this study, the spatial variability of soil REEs in Zhuxi watershed, Changting County, southern China, was analyzed using a geostatistics method. The analysis produced several important results: (1) The content of total rare earth elements (TREEs) in the soil samples ranged from 56.04 to 951.76 mg kg−1, with a mean value of 255.34 mg kg−1, which was higher than the background value of soil in China. The REE variables showed strong positive Ce anomalies and strong negative Eu anomalies, with mean values of 2.26 and 0.44, respectively. (2) The contents of TREEs in five subtypes of the soils were different, but they had broadly similar curves of chondrite-normalized REE patterns, with steeper patterns from La to Eu and flatter patterns from Eu to Y. (3) The spatial variability of light rare earth elements (LREEs) was mainly affected by natural factors, but the spatial variabilities of heavy rare earth elements (HREEs) and TREEs were influenced by the combination of natural factors and anthropogenic factors. Soil erosion can contribute significantly to REE migration, especially for HREEs. (4) The distribution of TREEs showed that the high content of TREEs was in the lowland of the western watershed. By comparing the distributions of TREEs in paddy fields and hilly land, we found that the area with a high content of TREEs was greater in paddy fields than in hilly land, so we deduced that REEs migrate from hilly land to the paddy field and accumulate in the soil there. [ABSTRACT FROM AUTHOR]

This paper studies the heterogeneous effects of exchange rate and stock market on carbon emission allowance price in four emissions trading scheme pilots in China. We employ a panel quantile regression model, which can describe both individual and distributional heterogeneity. The empirical results illustrate that the effects of explanatory variables on carbon emission allowance price is heterogeneous along the whole quantiles. Specifically, exchange rate has a negative effect on carbon emission allowance price at lower quantiles, while becomes a positive effect at higher quantiles. In addition, a negative effect exists between domestic stock market and carbon emission allowance price, and the intensity decreasing along with the increase of quantile. By contrast, an increasing positive effect is discovered between European stock market and domestic carbon emission allowance prices. Finally, heterogeneous effects on carbon emission allowance price can also be proved in European Union Emission Trading Scheme (EU-ETS). [ABSTRACT FROM AUTHOR]

Although it is generally agreed that public primary education should be equally available to all, a spatial disparity of educational opportunity exists worldwide, for wealthy families can acquire residential locations with better access to the best schools. Random allocation of school places is considered to be an effective approach for breaking such spatial linkages. This study addresses the problem of achieving the optimal spatial equality of educational opportunity by re-assigning school places to demand nodes using a combined mechanism that introduces a random allocation into a proximity-based system. This study proposes the use of a probability distribution for a full description of educational opportunity. A new spatial allocation optimization model towards equal educational opportunity with the maximum school travel distance constraints and capacities constraints was developed to maximize the resemblance between the probability distributions across demand nodes (RES-based model). This model was applied to a case study of primary school allocation in the Shijingshan District of Beijing, China, and was resolved in a heuristic way. The solution was compared with those provided by a capacitated proximity-based model and a model also using the random mechanism but measuring educational opportunity by expectation values (VAR-based model). It was found that the introducing of random mechanism could significantly improve the spatial equality of educational opportunity with a significant loss of spatial efficiency. In addition, the solution provided by the RES-based model was quite different to that provided by the VAR-based model. An improvement in the resemblance of demand node probability distributions might lead to an increase in the variance of expectations. The resemblance approach proposed in this study may also be applied to the optimization of other random objectives. • A Monte-Carlo-based framework is used to maximize the spatial equality in a proximity-based random system. • The resemblance of possibility distributions is used to define the objective of spatial equality of educational opportunity. • The problem of maximum resemblance is converted into a problem of minimizing total distance in multi-dimensional space. [ABSTRACT FROM AUTHOR]

A provincial Disaster-causing Rainstorm Severity Index(DRaSI) is introduced to quantify the relationship between rainfall and its disastrous impacts on Zhejiang province of China, shortened as ZJ-DRaSI. ZJ-DRaSI is set up based on the DRaSI for single stations in combination with the coverage of rainstorms. The probability distribution function(PDF) of ZJ-DRaSI between 1971 and 2015 can be well fitted by the Wakeby Distribution with five parameters. It is found that decadal(e.g. 10 yr, 20 yr, and so on) return period values of ZJ-DRaSI related to typhoons are generally lower than that of non-typhoon events, implying that disastrous non-typhoon events have a higher frequency of occurrence. The extreme typhoon events have a significant cycle of 22.5 years, while the non-typhoon events have a significant cycle of 15 years. Both are currently at the high-value phase. The annual extreme value of ZJ-DRaSI exhibits an increasing trend of approximately 15% every 10 years. [ABSTRACT FROM AUTHOR]

Lane change violations are a major cause of traffic conflicts and accidents at urban intersections and one of many road-safety issues in China. This study aims to explore the socio-psychological factors underlying drivers’ motivation for lane change violation behavior at urban intersections and examines how these factors predict this violation behavior. A self-reported questionnaire is designed by applying the construct of the theory of planned behavior (TPB) to collect data. Five hundred-six valid responses are received from the questionnaire survey conducted on the Internet in China. The data are then analyzed using structural equation modeling (SEM). The results of the analysis show that behavioral intention is the strongest predictor of self-reported lane change violation behavior at urban intersections. Perceived behavioral control has both direct and indirect effects on self-reported lane change violation behavior. Furthermore, attitude, subjective norms and perceived behavioral control are found to have significant correlations with drivers’ intention of lane change violations at urban intersections. The results of this study could provide a reference for designing more effective interventions to modify drivers’ lane change violation behavior at urban intersections. [ABSTRACT FROM AUTHOR]

The Ministry of Industry and Information Technology (MIIT) universities are important bases for science and technology research and play a critical role in China’s National Innovation System. Based on the Web of Science (WoS), this article analyzes the statistics of paper published by MIIT universities and universities from across China including MIIT universities. The results are as follows: (1) Both the MIIT universities and universities nationwide in China have increased their international academic publications, and MIIT have shown a greater increase for the past decade. (2) In terms of U-I-G interaction, for UG relations, the Tug value of MIIT universities has remained stable, while that of universities in China has become declined. For UI relations, the Tui value of both MIIT universities and universities in China has shown steady growth. For UIG relations, MIIT universities have a greater synergistic effect of Triple Helix relationship than universities in China. (3) For more details in seven MIIT universities, universities elected into “Project 985”, including HIT, BUAA, BIT and NPU, have published more papers, and been more synergistic with government and industry (UIG relations) than other three universities, including NUAA, NUST and HEU. Based on the empirical results, we discuss our findings, and make certain suggestions regarding policy incentives, reasonable administrative system and U-I-G interaction mode, which is significant not only for Chinese universities but also for universities in other developing countries. [ABSTRACT FROM AUTHOR]

Based on carbon spot prices selected from seven carbon pilots, we assess the financial performances related to carbon volatility in China on the overall perspective. According to the results, the Chinese carbon market fluctuated severely at the beginning of carbon trading, but has stabilised in general, despite several dramatic changes related to ‘yearly compliance events’. Long-term memory exists in the volatility series. Moreover, asymmetry exists in the Chinese carbon market, and volatility reacts more severely to good news than to bad news. Finally, we discuss our empirical results, and make certain suggestions regarding firms’ awareness, international cooperation and individual investors not only for policy makers in China but also for other developing countries who are contemplating either commencing carbon trading or improving the current market. [ABSTRACT FROM AUTHOR]

Bridge vehicle load is an important parameter that is relevant to the construction and maintenance stages of a bridge. In recent years, a large number of orthotropic steel deck bridges have been built in China, and it is urgent to establish a fatigue load model that reflects the actual traffic conditions of the bridges. This study has investigated the variation of vehicles over time on four grades of road (expressway, first-class highway, second-class highway and urban main road) according to the weight-in-motion (WIM) data. Subsequently, the statistical model was established in terms of speed, axle weight, and gross weight of vehicle (GVW) acting on the four grades of road. Finally, a fatigue load model of vehicles on the four grades of road was established based on a two-stage method. The results show that (1) the speed of vehicle on the four grades of road obeys the unimodal distribution; (2) the GVW of two- and three-axle vehicles on the four grades of road belongs to the t -distribution and the log-normal distribution, respectively; (3) the GVW of four- and five-axle vehicles on expressways is a finite mixed distribution, whereas the GVW of four- and five-axle vehicles on the remain three grades of road obeys the log-logistic and log-normal distribution respectively; (4) the GVW of six- and above axle vehicles on expressways and second-class highways obeys a finite mixed distribution with two variables, whereas that on first-class and urban main roads obeys the log-normal distribution; (5) the axle weight of standard fatigue vehicles differs remarkably on different grades of roads, which is difficult to describe the fatigue damage in a uniform standard fatigue vehicle. [ABSTRACT FROM AUTHOR]

In this study, an interval-parameter chanced-constrained full-infinite programming (ICFP) model based on Monte Carlo simulation is proposed for supporting water quality management under uncertainty (expressed as interval parameters, probability distribution, and functional intervals), and analyzing the reliability of satisfying (or the risk of violating) various constraints. The ICFP model was applied to investigate the utility of the model for managing industry development under water quality constraints in the Ankang section of the Hanjiang River Basin, which faces threats of point and nonpoint source pollution. The research area is one of the water sources of the South-to-North Water Diversion, which is a national strategic project aimed at mitigating the water shortage in north and northwest China. The results indicated that higher discharge amounts of chemical oxygen demand occur at the medicine manufacturing industry. Tradeoffs between economic benefits and system-failure risks were also examined. Alternative policy can be obtained from different combinations of decision variables within their lower and upper bounds, which are valuable for decision makers, who need to develop the desired regional economic plans while satisfying environmental requirements. [ABSTRACT FROM AUTHOR]

Latitude is an important factor that influences the carbon stock of Moso bamboo (Phyllostachys pubescens) forests. Accurate estimation of the carbon stock of Moso bamboo forest can contribute to sufficient evaluation of forests in carbon sequestration worldwide. Nevertheless, the effect of latitude on the carbon stock of Moso bamboo remains unclear. In this study, a field survey with 36 plots of Moso bamboo forests along a latitude gradient was conducted to investigate carbon stock. Results showed that the diameter at breast height (DBH) of Moso bamboo culms increased from 8.37 cm to 10.12 cm that well fitted by Weibull model, whereas the bamboo culm density decreased from 4722 culm ha−1 to 3400 culm ha−1 with increasing latitude. The bamboo biomass carbon decreased from 60.58 Mg C ha−1 to 48.31 Mg C ha−1 from north to south. The total carbon stock of Moso bamboo forests, which comprises soil and biomass carbon, ranged from 87.83 Mg C ha−1 to 119.5 Mg C ha−1 and linearly increased with latitude. As a fast-growing plant, Moso bamboo could be harvested amounts of 6.0 Mg C ha−1 to 7.6 Mg C ha−1 annually, which indicates a high potential of this species for carbon sequestration. Parameters obtained in this study can be used to accurately estimate the carbon stock of Moso bamboo forest to establish models of the global carbon balance. [ABSTRACT FROM AUTHOR]

Sichuan Basin is located in southwestern China and affected by a complex water vapor (WV) sources. Here, the spatial and temporal patterns of precipitation and extreme events are investigated by six indices of World Meteorology Organization Commission, including annual precipitation total (AP), maximum daily precipitation (Max1d), intensity of rainfall over 1 mm/d (IR1), maximum and mean consecutive dry days (Max CDD, Mean CDD) and coefficient of variance. Based on 24 daily precipitation time series from 1951 to 2011, Mann-Kendall test is employed to quantify the significant level of these indices, from which the classification of precipitation change and its spatial patterns are obtained. Meanwhile, the probability distributions of these indices are identified by L-moment analysis and the Goodness-of-fit test, and the corresponding values are calculated by theoretical model at different return periods. The results reveal that the western basin displays normal drought: less AP and precipitation intensity while longer drought. The southern basin shows normal increase: larger AP and precipitation intensity but shorter CDD. However, in hilly region of the central basin and the transition zone between basin and mountains, precipitation changes abnormally: increasing both drought (one or both of Mean CDD and MaxCDD) and precipitation intensity (one or both of Max1d and IR1) no matter what the trend of AP is. Probability distribution models also demonstrate the complex patterns: a negative correlation between Max1d and Max CDD in the west ( R ≥0.61) while a positive correlation in the east ( R ≥0.41) at all return periods. These patterns are induced by the changes in WV sources and the layout of local terrain. The increase of WV in summer and decrease in spring leads to the heavier rainfall and longer drought respectively. The large heat island effect of the basin contributes to a lower temperature in transition zones and more precipitation in the downwind area. These results are helpful in reevaluating the risk regionally and making better decisions on water resources management and disaster prevention. [ABSTRACT FROM AUTHOR]

Based on daily mean temperature at 1863 meteorological stations in China, the trend in the thermal growing season was investigated and time-evolving probability distributions of temperature were examined. Results showed that during 1961–2015, the growing season was extended at rates of 1.5–5.0 days decade−1in Northeast China, North China, Northwest China, and western and central parts of Southwest China. This change was ascribed to an earlier start of the growing season at rates of 1.5–3.0 days decade−1in North China, the northern and western parts of Northeast China, and the northeastern part of Northwest China, and a later end at rates of 0.5–2.5 days decade−1in Northwest China, the western and northern parts of Southwest China, and the northwest of North China. The earlier start of the growing season was in accordance with the rapid warming of lower portions of the spring temperature distribution in Northeast China, North China, and Northwest China. The later end of the growing season corresponded to rapid warming in the lower percentiles of autumn temperature distribution in Northwest China. The growing season is more sensitive to warming of lower percentiles of temperature distribution than other portions. [ABSTRACT FROM AUTHOR]

We investigate the probability distribution of order imbalance calculated from the order flow data of 43 Chinese stocks traded on the Shenzhen Stock Exchange. Two definitions of order imbalance are considered based on the order number and the order size. We find that the order imbalance distributions of individual stocks have power-law tails. However, the tail index fluctuates remarkably from stock to stock. We also investigate the distributions of aggregated order imbalance of all stocks at different timescales Δ t . We find no clear trend in the tail index with respect Δ t . All the analyses suggest that the distributions of order imbalance are asymmetric. [ABSTRACT FROM AUTHOR]

As a huge threat to the public health, China’s air pollution has attracted extensive attention and continues to grow in tandem with the economy. Although the real-time air quality report can be utilized to update our knowledge on air quality, questions about how pollutants evolve across time and how pollutants are spatially correlated still remain a puzzle. In view of this point, we adopt the PMFG network method to analyze the six pollutants’ hourly data in 350 Chinese cities in an attempt to find out how these pollutants are correlated temporally and spatially. In terms of time dimension, the results indicate that, except for O3, the pollutants have a common feature of the strong intraday patterns of which the daily variations are composed of two contraction periods and two expansion periods. Besides, all the time series of the six pollutants possess strong long-term correlations, and this temporal memory effect helps to explain why smoggy days are always followed by one after another. In terms of space dimension, the correlation structure shows that O3 is characterized by the highest spatial connections. The PMFGs reveal the relationship between this spatial correlation and provincial administrative divisions by filtering the hierarchical structure in the correlation matrix and refining the cliques as the tinny spatial clusters. Finally, we check the stability of the correlation structure and conclude that, except for PM10 and O3, the other pollutants have an overall stable correlation, and all pollutants have a slight trend to become more divergent in space. These results not only enhance our understanding of the air pollutants’ evolutionary process, but also shed lights on the application of complex network methods into geographic issues. [ABSTRACT FROM AUTHOR]

Using 5-minute high frequency data from the Chinese stock market, we employ a non-parametric method to estimate Fama-French portfolio realized jumps and investigate whether the estimated positive, negative and sign realized jumps could forecast or explain the cross-sectional stock returns. The Fama-MacBeth regression results show that not only have the realized jump components and the continuous volatility been compensated with risk premium, but also that the negative jump risk, the positive jump risk and the sign jump risk, to some extent, could explain the return of the stock portfolios. Therefore, we should pay high attention to the downside tail risk and the upside tail risk. [ABSTRACT FROM AUTHOR]

The refill operation of Three Gorges Reservoir (TGR) in the end of flood season significantly alters the water level regimes in Poyang Lake by reducing Yangtze River flow discharge. This study aims to investigate the impact of TGR refill operation on water level probability distribution of the Poyang Lake. The multiple linear regression model was established to estimate the water level with catchment inflow and Yangtze River flow as explanatory variables. A probability distribution of water level was derived and the refill operation effects were quantified by comparing the water level distribution at Xingzi station in the Poyang Lake before and after TGR. It is revealed that Yangtze River flow, rather than the catchment inflow is the dominant factor affecting the water level of Poyang Lake during TGR refill operation period. Results also show that the water level distribution estimated by the derived distribution method can be accepted as a theoretical distribution and has a comparable accuracy as the directly fitted distribution method before TGR. The derived method can be adapted to the environment change, thus is well suited for estimating the water level distribution after TGR. It is observed that Xingzi water levels with different design frequencies have been reduced due to the TGR refill operation. The water level reductions induced by TGR refill operation are 1.28, 0.87, and 0.50 m corresponding with design frequencies of 50, 90 and 99 %, respectively. The results from this work would improve the understanding of the TGR effects on the downstream river-lake system and provide scientific evidences for formulating better scheme for water resources management in this region. [ABSTRACT FROM AUTHOR]

Shale has been considered as good gas reservoir due to its abundant interior nanoscale pores. Thus, the study of the pore structure of shale is of great significance for the evaluation and development of shale oil and gas. To date, the most widely used approaches for studying the shale pore structure include image analysis, radiation and fluid invasion methods. The detailed pore structures can be studied intuitively by image analysis and radiation methods, but the results obtained are quite sensitive to sample preparation, equipment performance and experimental operation. In contrast, the fluid invasion method can be used to obtain information on pore size distribution and pore structure, but the relative simple parameters derived cannot be used to evaluate the pore structure of shale comprehensively and quantitatively. To characterize the nanoscale pore structure of shale reservoir more effectively and expand the current research techniques, we proposed a new method based on gas adsorption experimental data and the method of moments to describe the pore structure parameters of shale reservoir. Combined with the geological mixture empirical distribution and the method of moments estimation principle, the new method calculates the characteristic parameters of shale, including the mean pore size (), standard deviation (σ), skewness (Sk) and variation coefficient (c). These values are found by reconstructing the grouping intervals of observation values and optimizing algorithms for eigenvalues. This approach assures a more effective description of the characteristics of nanoscale pore structures. Finally, the new method has been applied to analyze the Yanchang shale in the Ordos Basin (China) and Longmaxi shale from the Sichuan Basin (China). The results obtained well reveal the pore characteristics of shale, indicating the feasibility of this new method in the study of the pore structure of shale reservoir. [ABSTRACT FROM AUTHOR]

Background: Hand, Foot, and Mouth Disease (HFMD) is a worldwide infectious disease. In China, many provinces have reported HFMD cases, especially the south and southwest provinces. Many studies have found a strong association between the incidence of HFMD and climatic factors such as temperature, rainfall, and relative humidity. However, few studies have analyzed cluster effects between various geographical units. Methods: The nonlinear relationships and lag effects between weekly HFMD cases and climatic variables were estimated for the period of 2008–2013 using a polynomial distributed lag model. The extra-Poisson multilevel spatial polynomial model was used to model the exact relationship between weekly HFMD incidence and climatic variables after considering cluster effects, provincial correlated structure of HFMD incidence and overdispersion. The smoothing spline methods were used to detect threshold effects between climatic factors and HFMD incidence. Results: The HFMD incidence spatial heterogeneity distributed among provinces, and the scale measurement of overdispersion was 548.077. After controlling for long-term trends, spatial heterogeneity and overdispersion, temperature was highly associated with HFMD incidence. Weekly average temperature and weekly temperature difference approximate inverse “V” shape and “V” shape relationships associated with HFMD incidence. The lag effects for weekly average temperature and weekly temperature difference were 3 weeks and 2 weeks. High spatial correlated HFMD incidence were detected in northern, central and southern province. Temperature can be used to explain most of variation of HFMD incidence in southern and northeastern provinces. After adjustment for temperature, eastern and Northern provinces still had high variation HFMD incidence. Conclusion: We found a relatively strong association between weekly HFMD incidence and weekly average temperature. The association between the HFMD incidence and climatic variables spatial heterogeneity distributed across provinces. Future research should explore the risk factors that cause spatial correlated structure or high variation of HFMD incidence which can be explained by temperature. When analyzing association between HFMD incidence and climatic variables, spatial heterogeneity among provinces should be evaluated. Moreover, the extra-Poisson multilevel model was capable of modeling the association between overdispersion of HFMD incidence and climatic variables. [ABSTRACT FROM AUTHOR]

In this study, we apply an integrated empirical and mechanism approach to estimate a comprehensive long-term (1953–2012) total nitrogen (TN) and total phosphorus (TP) loading budget for the eutrophic Lake Chaohu in China. This budget is subsequently validated, firstly, by comparing with the available measured data in several years, and secondly, by model simulations for long-term nutrient dynamics using both Vollenweider (VW) model and dynamic nonlinear (DyN) model. Results show that the estimated nutrient budget is applicable for further evaluations. Surprisingly, nutrient loading from non-point sources (85% for TN and 77% for TP on average) is higher than expectation, suggesting the importance of nutrient flux from the soil in the basin. In addition, DyN model performs relatively better than VW model, which is attributed to both the additional sediment recycling process and the parameters adjusted by the Bayesian-based Markov Chain Monte Carlo (MCMC) method. DyN model further shows that the TP loading thresholds from the clear to turbid state (631.8 ± 290.16 t y −1 ) and from the turbid to clear state (546.0 ± 319.80 t y −1 ) are significantly different ( p < 0.01). Nevertheless, the uncertainty ranges of the thresholds are largely overlapped, which is consistent with the results that the eutrophication of Lake Chaohu is more likely to be reversible (74.12%) than hysteretic (25.53%). The ecosystem of Lake Chaohu shifted from the clear to turbid state during late 1970s. For managers, approximately two-thirds of the current TP loading must be reduced for a shift back with substantial improvement in water quality. Because in practice the reduction of loading from a non-point source is very difficult and costly, additional methods beyond nutrient reduction, such as water level regulation, should be considered for the lake restoration. [ABSTRACT FROM AUTHOR]

Abstract: We choice the yuan exchange rate index based on a basket of currencies as the effective exchange rate of the yuan and investigate the statistical properties of the yuan exchange rate index after China’s exchange rate system reform on the 21st July 2005. After dividing the time series into two parts according to the change in the yuan exchange rate regime in July 2008, we compare the statistical properties of the yuan exchange rate index during these two periods. We find that the distribution of the two return series has the exponential form. We also perform the detrending moving average analysis (DMA) and the multifractal detrending moving average analysis (MFDMA). The two periods possess different degrees of long-range correlations, and the multifractal nature is also unveiled in these two time series. Significant difference is found in the scaling exponents and singularity spectra of the two periods obtained from the MFDMA analysis. Besides, in order to detect the sources of multifractality, shuffling and phase randomization procedures are applied to destroy the long-range temporal correlation and fat-tailed distribution of the yuan exchange rate index respectively. We find that the fat-tailedness plays a critical role in the sources of multifractality in the first period, while the long memory is the major cause in the second period. The results suggest that the change in China’s exchange rate regime in July 2008 gives rise to the different multifractal properties of the yuan exchange rate index in these two periods, and thus has an effect on the effective exchange rate of the yuan after the exchange rate reform on the 21st July 2005. [Copyright &y& Elsevier]

Twelve-hour real-time and synchronous measurements of the three-dimensional components of the near-surface turbulence at four heights (8, 16, 32 and 47 m) during a dust storm are obtained by sonic anemometers for the first time. The experimental results show that (1) the mean vertical velocities at all four heights have considerably positive values during the dust storm, illustrating a strong upward flow near the surface; (2) during the dust storm, the mean vertical velocity is higher at 8 m than at 16 and 32 m, implying that the convection is stronger at 8 m than at the other two heights; and (3) when the longitudinal velocity is a maximum, the mean of the vertical components of wind velocities at 8 m is a minimum and the standard deviation is a maximum, which reveals weaker vertical convection during the period of greatest dust storm intensity, while the turbulence intensity contrarily increases, which may result in more entrainment of surface dust. The analysis results also show that the standard deviations of the longitudinal and vertical velocities increase as the mean inflow velocity increases, but the standard deviation of the lateral velocity is hardly affected by the mean inflow velocity. Based on the calculated skewness and kurtosis of the longitudinal, vertical and lateral velocities every 20 min at different heights, it is seen that all three components obviously fluctuate with height, which further indicates the importance of performing real-time and synchronous measurements at different heights near the surface during a dust storm so as to reveal the three-dimensional turbulence structure accurately. [ABSTRACT FROM AUTHOR]

Abstract: The spatial distribution patterns of permafrost affect the stability of engineering facilities in high-cold regions. A transportation corridor, located in the northeastern Qinghai province of China, and passing through the Qilianshan high-mountain permafrost area is investigated. Two field investigations were carried out and a total of 220 boreholes were drilled to determine the distribution patterns of permafrost along the corridor. On the basis of the borehole data the effects of topo-climatic factors, derived from a 90 m-DEM data, on permafrost distribution were evaluated. Two models, a binary logistic regression model and a multi-criteria analysis model, were developed and validated based on a sub-group of 67 boreholes data and all the 220 borehole measurements. A comparison of the results of the two models indicated that the prediction probabilities of permafrost presence from the multi-criteria analysis model agreed well with the field investigations. The multi-criteria analysis model was shown to be the more efficient one in modeling the permafrost distribution in the corridor area. The overall permafrost distribution patterns were analyzed using the ARCGIS software. [Copyright &y& Elsevier]

Abstract: Using ultra-high-frequency data extracted from the order flows of 23 stocks traded on the Shenzhen Stock Exchange, we study the empirical regularities of order placement in the opening call auction, cool period and continuous auction. The distributions of relative logarithmic prices against reference prices in the three time periods are qualitatively the same with quantitative discrepancies. The order placement behavior is asymmetric between buyers and sellers and between the inside-the-book orders and outside-the-book orders. In addition, the conditional distributions of relative prices in the continuous auction are independent of the bid–ask spread and volatility. These findings are crucial to build an empirical behavioral microscopic model based on order flows for Chinese stocks. [Copyright &y& Elsevier]

• A PDF for drought duration following an independent Bernoulli process is derived. • A PDF for drought duration following a Markov-dependent process is derived. • The drought duration follows the geometric distribution II. • Results provide a guidance for modeling hydrological and meteorological droughts. The probability of drought duration is a key for drought management. Literature survey shows that drought duration has been assumed to follow the geometric distribution I, but it yields zero probability of a drought with duration equal to zero which, however, is not consistent with reality. This shortcoming served as a motivation to derive a new distribution for the probability of drought duration. Using an independent Bernoulli process and a Markov-dependent process, it was found that the drought duration followed the geometric distribution II. Results of the derived distribution were in agreement with those of a simulation study results. Four examples from Yellow River basin in China were used to illustrate the application of the proposed distribution. [ABSTRACT FROM AUTHOR]

The density and modulus of elasticity (MOE) distribution can provide information on the effectiveness of parametric and non-parametric methods in calculating the characteristic value of MOE. In this study, we aim to determine the optimal distribution model of the actual measured data of the lumber. We also estimate the lumber's MOE characteristic value and compare the difference in density and MOE between natural and planted larch. Approximately 1200 pieces of dimension lumber of 4 m × 140 mm × 40 mm in size, made from larch and planted larch, were obtained, tested, and the corresponding standard MOE value was calculated. Results revealed the 3-parameter Weibull distribution to be optimal in fitting the natural and planted larch distributions. The parametric method proved effective in calculating the characteristic value of both larch groups, with characteristic MOE values of 9.73 kN/mm2 and 8.84 kN/mm2, and characteristic density values of 530 kg/m3 and 460 kg/m3 for natural and planted larch, respectively. Moreover, the MOE and density values followed grades C40 and C35. Thus, the conclusion is that the parametric method should be used to determine these characteristic values for natural and planted larch. [ABSTRACT FROM AUTHOR]

A kernel density estimation (KDE) model for the probability distribution of wind speed (PDWS) is proposed in this paper for application to wind energy assessment (WEA) in China. Four bandwidth selectors, including normal scale (NS), plug in, biased cross-validation, and least-square cross validation, are proposed for the KDE model. Popular parametric distribution models are also introduced for comparisons with the KDE models. Based on five-year day-average wind speed data from 698 nationwide wind stations in China, the performance and robustness of both parametric and KDE models were evaluated comprehensively on the regional scale. Wind power density (WPD) and wind turbine power output (WTPO), which are the priorities in WEA, are subsequently calculated based on the estimated PDWS models. The ranking results of four individual metrics and one comprehensive metric indicate that the four KDE models outperform the parametric models in fitting the PDWS. The KDE-NS model performs the best compared to the other three KDE models. In addition to the KDE models, the generalized gamma and generalized extreme values were considered as better parametric models in fitting the PDWS. KDE models also performed well in WPD estimation, especially the KDE-NS model with a mean absolute percentage error (MAPE) value as low as 2%. Some parametric models, i.e., Johnson SB and Wakeby, which are not outstanding in PDWS fitting, however perform well in WPD estimation, and their MAPE values can be controlled to remain within 3%. This indicates that the result of the PDWS is not completely equivalent to that of WPD estimation. The WPD and WTPO in most of China's interior areas are less than 40 W / m 2 and 1.2 GWh, respectively. In the eastern coastal areas, middle and eastern Inner Mongolia, and some western provinces, the WPD and WTPO are relatively higher, and can reach or exceed 240 W / m 2 and 3.5 GWh, respectively. • Four KDE models with various bandwidth selectors are proposed for fitting PDWS. • Popular parametric models are introduced for comparisons with the KDE models. • Performance of parametric and KDE models are evaluated on the regional scale. • KDE models generally outperform the parametric models in fitting PDWS. • KDE models also performs well in WEA analysis, especially for the KDE-NS. [ABSTRACT FROM AUTHOR]

We used statistical methods and the GEOS-Chem model to interpret the observed spatiotemporal and probability variations of surface PM 2.5 concentrations in China from December 2013 to November 2019, as well as to assess the drivers for the variations and the implications for health risks associated with long-term and short-term exposure to PM 2.5 . Annual and seasonal PM 2.5 concentrations have decreased over most areas in China during the 6-year period. We decomposed the observed day-to-day variation of PM 2.5 concentrations in eastern Chinese cities and found that it showed two distinct major spatial modes, which fluctuated in strength seasonally. The first mode, characterized by most of Eastern China being in the same phase, was mainly associated with the regional ventilation of pollutants. The second mode showed a dipolar pattern between the Beijing-Tianjin-Hebei area and the Yangtze River Delta area and was more prominent in summer. Using model simulations, we showed that this dipole mode was chemically driven by the secondary formation of sulfate in summer. We further used a gamma distribution to succinctly interpret the changes in the probability distributions of PM 2.5 . We found that the nationwide decline in seasonal mean PM 2.5 concentrations mainly reflected decreased occurrences of extremely high PM 2.5 concentrations, which was strongly driven by the interannual variation of meteorology. These changes in the annual means and probability distributions of PM 2.5 since December 2013 has led to significant decline of the estimated mortality risks associated with long-term and short-term PM 2.5 -exposures. Regions that were less polluted saw the largest relative benefit per unit decrease in PM 2.5 concentration, due to the steepness of the exposure-response curve at the low-concentration end. Our integrated methodology effectively diagnosed the drivers of PM 2.5 variability and the associated health risks and can be used as part of the decision tool for PM 2.5 pollution management over China., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 The Authors. Published by Elsevier B.V. All rights reserved.)

The objective of this study was to develop predictive models for describing the inoculated Salmonella reductions on chicken during the scalding process in China. Salmonella reductions on chicken breasts at a 100 s treatment were 1.12 ± 0.07, 1.38 ± 0.01, and 2.17 ± 0.11 log CFU/g at scalding temperatures of 50, 60 and 70 °C, respectively. For chicken wingettes, 0.87 ± 0.02, 0.99 ± 0.14 and 1.11 ± 0.17 log CFU/g reductions were obtained at 50, 60 and 70 °C after the 100 s treatment, respectively. Greater bacterial reductions were observed on chicken breasts than on chicken wingettes (p < 0.05). A logistic (−1.12, 0.06) distribution could describe the bacterial reductions on chicken breasts at 50–60 °C. Weibull, exponential and log-linear models were compared for describing the bacterial reduction on chicken breasts at 70 °C and the Weibull model showed the best fit as indicated by the pseudo-R2, root mean square error (RMSE) and standard error of prediction (SEP) values. For chicken wingettes, a logistic (−0.95, 0.07) distribution could be used to describe the bacterial reduction at 50–70 °C. The developed predictive models could provide parts of the input data for microbial risk assessment of the poultry supply chain in China. [ABSTRACT FROM AUTHOR]

Based on catch data from the bottom trawl survey by eight cruises in offshore of northern South China Sea during 2014-2017, we analyzed the stock density distribution and explored its probability distribution with statistical method, which was further used to estimate the mean stock density in this region. The results showed that the coefficient of variation (CV) for stock density ranged from 0.67 to 1.03 for all the periods, indicating a highly uneven spatial distribution of stock density. The frequency distribution of fishery resource density was characterized by obvious right-skewed, which was dominated by stock density of 0-1000 kg·km -2 . The results of one sample Kolmogorov-Smirnov test indicated that three probability distribution patterns were suitable for stock density in this region, including Lognormal, Gamma and Weibull distributions. In terms of the mean stock density estimation, the values from Lognormal showed no statistically significant difference from those from others, but the opposite result was obtained between Gamma and Weibull distributions. Compared with 1960s-1970s, the appropriate probability distribution pattern of stock density has changed from single to multiple types. Variation of the proportion of low catch resulted from the changes in the structure of fishery resources, fishing effort and climate change might cause the alte-ration of probability distribution.

Background: Vibrio parahaemolyticus is an important gastroenteritis pathogen contaminating seafood in China. In this study a total of 992 seafood samples from major hypermarkets in Shanghai were monitored for prevalence and burden of V. parahaemolyticus from January 2011 to December 2012. Additionally, appropriate probability distributions for describing V. parahaemolyticus concentrations were assessed based on these surveillance data., Results: Seventeen of 992 samples were positive for V. parahaemolyticus and the geometric mean was 0.1581 most probable number (MPN) g -1 . The variation in prevalence of V. parahaemolyticus was seasonal and the burden of contamination in August (0.1942 MPN g -1 ) was significant (P < 0.01) between 2011 and 2012. Also, the prevalence of V. parahaemolyticus was higher in shellfish and cephalopods than in other seafood (P < 0.05). By comparison, the lognormal distribution and integrated distribution showed no obvious difference for characterizing V. parahaemolyticus contamination., Conclusion: The low prevalence and burden found indicated that seafood from hypermarkets may not be an important risk source for V. parahaemolyticus infection in Shanghai, and more attention should be paid to other areas for selling seafood, such as farmlands or farmers' markets. The simple and effective lognormal distribution is recommended as a better choice for describing V. parahaemolyticus contamination in future risk assessment studies. © 2016 Society of Chemical Industry., (© 2016 Society of Chemical Industry.)