scholarly journals Joint improvement of river water quality indicators based on a multivariate joint probability distribution of the discharge and water quality

2018 ◽  
Vol 49 (6) ◽  
pp. 1915-1928 ◽  
Author(s):  
Yang Liu ◽  
Shengle Cao ◽  
Xi Zhang ◽  
Fuzhen Li ◽  
Xitong Li
Keyword(s):  
Water Quality ◽  
Probability Distribution ◽  
River Water ◽  
Quality Indicators ◽  
Joint Probability ◽  
Copula Function ◽  
River Water Quality ◽  
Statistical Characteristics ◽  
Joint Probability Distribution ◽  
Water Quality Indicators

Abstract Based on the multivariate joint probability distribution of the discharge and water quality indicators, this paper analysed the occurrence probabilities and improvement probabilities of combinations of water quality indicators under different discharge conditions and then presented a method for calculating the optimal discharge to seek a balance between the discharge dispatch and water quality improvement. The method was used to construct the relationship curve between the discharge and joint improvement probability used by a copula function and then calculate the critical point on the curve. The proposed method was applied to the Yi River Basin above Gegou Station with data composed of the discharge and main pollution indicators (NH3-N and CODMn) from 1982 to 2015. The results showed that the trivariate joint probability distribution can more reasonably reveal the statistical characteristics of different combinations of discharge and water quality indicators. Furthermore, the optimal discharges and the corresponding improvement probabilities that improved NH3-N and CODMn to different grades were calculated. The calculation method took the interdependence of multiple water quality indicators into account, thereby providing a more reasonable method for using discharge dispatch data to improve the river water quality.

scholarly journals Combined Exceedance Probability Assessment of Water Quality Indicators Based on Multivariate Joint Probability Distribution in Urban Rivers

Water ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 971 ◽  
Author(s):  
Yang Liu ◽  
Yufei Cheng ◽  
Xi Zhang ◽  
Xitong Li ◽  
Shengle Cao
Keyword(s):  
Water Quality ◽  
Quality Indicators ◽  
Change Point ◽  
Probability Distributions ◽  
Joint Probability ◽  
Exceedance Probability ◽  
Joint Probability Distribution ◽  
Urban Rivers ◽  
Water Quality Indicators ◽  
Joint Probability Distributions

Discharge and water quality are two important attributes of rivers, although the joint response relationship between discharge and multiple water quality indicators is not clear. In this paper, the joint probability distributions are established by copula functions to reveal the statistical characteristics and occurrence probability of different combinations of discharge and multiple water quality indicators. Based on the data of discharge, ammonia nitrogen content index (NH4+) and permanganate index (CODMn) in the Xiaoqing River in Jinan, we first tested the joint change-point with the data from 1980–2016, before we focused on analyzing the data after the change-point and established the multivariate joint probability distributions. The results show that the Gaussian copula is more suitable for describing the joint distribution of discharge and water quality, while the year of 2005 is a joint change-point of water quantity and quality. Furthermore, it is more reasonable to use the trivariate joint probability distribution as compared to the bivariate distributions to reflect the exceedance probability of water quality combination events under different discharge conditions. The research results can provide technical support for the water quality management of urban rivers.

scholarly journals Copula-Based Method for Estimating the Minimum Void Ratio Parameters of Tailings Deposits

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Hao Li ◽  
Yichuan Tang ◽  
Shibo Li ◽  
Jianquan Ma ◽  
Xiaojie Zhao
Keyword(s):  
Probability Distribution ◽  
Fine Particle ◽  
Void Ratio ◽  
Joint Probability ◽  
Copula Function ◽  
Distribution Model ◽  
Joint Probability Distribution ◽  
Particle Content ◽  
Edge Distribution ◽  
Guarantee Rate

The pore ratio is an important parameter affecting the stability and safety of tailings reservoirs; however, the relationship between the pore ratio and physical properties of tailings sand has not been researched in-depth. In this paper, using the tailings from a tungsten mine in southern Shaanxi as a case study, the correlation between the minimum void ratio and related parameters is analyzed, based on laboratory test data, and the optimal marginal distribution function of the parameters is determined. The Gumbel-Hougard copula function that best describes the correlation between parameters is identified, and it is used to establish the joint probability distribution model of the three parameters, and the guarantee rate α is introduced to estimate and analyze the minimum void ratio. The results show that the optimal edge distribution of the fine particle content and specific gravity follows a truncated normal distribution, and the optimal edge distribution of the minimum void ratio follows a logarithmic normal distribution. According to AIC criterion, the Gumbel-Hougard copula is the best three-dimensional copula function to fit the minimum void ratio and related parameters. When the guarantee rate α is 0.485, the joint probability distribution model achieves optimal performance in terms of estimating the minimum void ratio. The maximum error of the estimation is 1.99%, which is verified through data, and the estimation meets the requirements for practical engineering. The method proposed in this paper uses the existing measured data to establish a joint probability distribution model and combines the collected fine particle content and specific gravity data with the guarantee rate to estimate the minimum void ratio, providing a novel basis for the study of the physical properties of tailings.

scholarly journals The joint probability distribution of runoff and sediment and its change characteristics with multi-time scales

2014 ◽  
Vol 62 (3) ◽  
pp. 218-225 ◽  
Author(s):  
Jinping Zhang ◽  
Zhihong Ding ◽  
Jinjun You
Keyword(s):  
Probability Distribution ◽  
Time Scales ◽  
Joint Probability ◽  
Copula Function ◽  
Annual Runoff ◽  
Joint Probability Distribution ◽  
Mode Decomposition ◽  
Change Characteristics ◽  
Empirical Mode Decomposition Method ◽  
Statistical Analysis Method

Abstract River runoff and sediment transport are two related random hydrologic variables. The traditional statistical analysis method usually requires those two variables to be linearly correlated, and also have an identical marginal distribution. Therefore, it is difficult to know exactly the characteristics of the runoff and sediment in reality. For this reason, copulas are applied to construct the joint probability distribution of runoff and sediment in this article. The risk of synchronous-asynchronous encounter probability of annual rich-poor runoff and sediment is also studied. At last, the characteristics of annual runoff and sediment with multi-time scales in its joint probability distribution space are simulated by empirical mode decomposition method. The results show that the copula function can simulate the joint probability distribution of runoff and sediment of Huaxia hydrological station in Weihe River well, and that such joint probability distribution has very complex change characteristics at time scales.

scholarly journals EVALUATION OF ELECTROMYOGRAPHIC NOISE STATISTICAL CHARACTERISTICS IN MULTICHANNEL ECG RECORDINGS

2019 ◽  
pp. 118-125
Author(s):  
Evgene B. Grigoriev ◽  
Alexander S. Krasichkov ◽  
Evgeny M. Nifontov
Keyword(s):  
Distribution Function ◽  
Probability Distribution ◽  
Probability Distribution Function ◽  
Joint Probability ◽  
Bivariate Normal Distribution ◽  
Statistical Characteristics ◽  
Joint Probability Distribution ◽  
Electrocardiogram Signal ◽  
Ecg Leads ◽  
Joint Probability Distribution Function

Electromyographic noise is one of the most common noises in electrocardiogram. In case of several electrocardiogram leads, electromyographic noise affects each lead to different extent. It can be taken into account when developing algorithms for multilead electrocardiogram record processing. However, in the existing literature, there is no information about the relationship of electromyographic noise in various ECG leads and their joint probability distribution. The purpose of this paper is to study statistical characteristics of electromyographic noise in ECG signal, from which the electromyographic noise is extracted. The paper proposes a method for extracting electromyographic noise from electrocardiogram signal, based on a polynomial approximation of electrocardiogram signal fragments in sliding window with overlapping fragment subsequent weight averaging. Using this method, fragments of electromyographic noise are extracted from multichannel electrocardiogram records. Based on the obtained data, a joint probability distribution function of electromyographic noise in two adjacent leads is selected, and the correlation relationships between the electromyographic noise in various ECG leads are investigated. The results show that the joint probability distribution function of electromyographic noise in two adjacent leads in the first approximation can be described using bivariate normal distribution. In addition, between the samples of electromyographic noise from two adjacent leads quite strong correlation relationships can be observed.

scholarly journals Temporal Analysis and the Joint Probability Distribution of Rainfall Indexes in the Taihu Lake Basin, China

2021 ◽  
Author(s):  
Manqiu Hao ◽  
Cheng Gao ◽  
Jian Chen
Keyword(s):  
Probability Distribution ◽  
Taihu Lake ◽  
Three Dimensional ◽  
Joint Probability ◽  
Daily Rainfall ◽  
Copula Function ◽  
Joint Probability Distribution ◽  
Lake Basin ◽  
Goodness Of Fit Test ◽  
Taihu Lake Basin

Abstract Taking the Taihu Lake Basin as an example, in this study, the characteristics of the rainfall factors in the study area were analyzed using daily rainfall data from 1955 to 2018. Three factors, i.e., the contribution rate of the rainfall in the flood season, the rainfall frequency, and the maximum daily rainfall, were selected to determine the optimal probability distribution function for each single factor. Furthermore, the root mean square error (RMSE) goodness of fit test was used to determine the optimal copula function for the three-dimensional joint probability distribution characteristics of the rainfall factors. The research results show that the three-dimensional copula joint probability method contains much more information than the results of the single variable probability calculation. The copula function can be used to analyze the multi-dimensional joint distribution of rainfall factors, which can fill the gap in research on multiple rainfall factors.

scholarly journals Modeling of extreme risk in river water quality under climate change

2018 ◽  
Vol 9 (3) ◽  
pp. 512-524 ◽  
Author(s):  
S. Rehana ◽  
C. T. Dhanya
Keyword(s):  
Water Quality ◽  
River Water ◽  
Water Quality Management ◽  
Copula Function ◽  
Climatic Conditions ◽  
River Water Quality ◽  
Average Risk ◽  
Modeling Framework ◽  
Model Based ◽  
Extreme Risk

Abstract A river water quality management model under average climatic conditions may not be able to account for the extreme risk of low water quality which is more prominent under an increase in river water temperature and altered river flows. A modeling framework is developed to assess the risk of river low water quality extremes by integrating a statistical downscaling model based on Canonical Correlation Analysis, risk quantification model based on Frank Archimedean Copula function and multiple logistic regression model integrated with a river water quality simulation model, QUAL2 K. The results reveal that the combination of predicted decrease in low flows of approximately 57% and increase in maximum river water temperatures of approximately 1.2°C has shown an increase of about 46% in risk of low water quality conditions for the future scenarios along Tunga-Bhadra River, India. The extreme risk of low water quality is observed to increase by 50.6% for the period 2020–2040 when compared with the current extreme conditions of 4.5% and average risk conditions of about 3% for the period 1988–2005. The study captured the occurrence of extremes of low water quality with evidence of a strong link between climate and water quality impairment events.

Application of a Pilot-Scale Pulsed Electrocoagulation system to OCC-Based Paper Mill Effluent

TAPPI Journal ◽  
2009 ◽  
Vol 8 (3) ◽  
pp. 14-20 ◽  
Author(s):  
YUAN-SHING PERNG ◽  
EUGENE I-CHEN WANG ◽  
SHIH-TSUNG YU ◽  
AN-YI CHANG
Keyword(s):  
Water Quality ◽  
Quality Indicators ◽  
Paper Mill ◽  
Pilot Scale ◽  
Operating Conditions ◽  
Optimal Dosage ◽  
Water Quality Indicators ◽  
Paper Mill Effluent ◽  
Treated Effluent ◽  
True Color

Trends toward closure of white water recirculation loops in papermaking often lead to a need for system modifications. We conducted a pilot-scale study using pulsed electrocoagulation technology to treat the effluent of an old corrugated containerboard (OCC)-based paper mill in order to evaluate its treatment performance. The operating variables were a current density of 0–240 A/m2, a hydraulic retention time (HRT) of 8–16 min, and a coagulant (anionic polyacrylamide) dosage of 0–22 mg/L. Water quality indicators investigated were electrical con-ductivity, suspended solids (SS), chemical oxygen demand (COD), and true color. The results were encouraging. Under the operating conditions without coagulant addition, the highest removals for conductivity, SS, COD, and true color were 39.8%, 85.7%, 70.5%, and 97.1%, respectively (with an HRT of 16 min). The use of a coagulant enhanced the removal of both conductivity and COD. With an optimal dosage of 20 mg/L and a shortened HRT of 10 min, the highest removal achieved for the four water quality indicators were 37.7%, 88.7%, 74.2%, and 91.7%, respectively. The water qualities thus attained should be adequate to allow reuse of a substantial portion of the treated effluent as process water makeup in papermaking.

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