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Study on adsorption of heavy metal ions onto insolublized humic acid
MA Ming-guang, ZHOU Min, JIANG Yu-feng, WU Ying-qin, ZHANG Yuan, CHEN Hui (Chemistry & Chemical Engineering College, Northwest Normal University, Lanzhou 730070, China)The present paper has investigated the removal of heavy metals Pb 2+, Cd 2+ and Cu 2+ from the aqueous solutions by adsorption onto insoluble humic acid (IHA) at different pH and temperatures. As is known, insoluble humic acid (IHA) has an excellent adsorptive ability, which can be prepared by heating the highly soluble HA at 330 ℃ and the treated with 2 mol/L CaCl2 solution. The insoluble humic acid are characterized by such means as thermo-gravimetry and differential thermal analysis (TG-DTA) as well as scanning electron micrograph (SEM). While investigating the effect of temperature, pH and time on the adsorption behaviors of heavy metals, it has found that the adsorption capacity increases with the increase of the temperature and pH. At the same time, the paper has also analyzed the adsorption experimental data by using three different isotherm models: Langmuir, Frendlich and Linear isotherm. As the result, it has obtained the optimal correlation for Frendlich isotherm equations. In addition, the paper has calculated the thermodynamic quantities ΔH in accordance with the Clausius-Claperyon,s theory. The ΔH values for Pb 2+,Cd 2+ and Cu 2+ prove to be -75.37 J/mol, -117.92 J/mol and -110.76 J/mol, respectively, which are smaller than the lower limit of the chenmisorption (42.0 kJ/mol ). It means that the type of adsorption of Pb 2+,Cd 2+ and Cu 2+ onto IHA is physisorption, rather than by chemical bonding. And finally, the adsorption equilibrium gained within 12 hours, and a high and stable removal of heavy metals on insoluble humic acid has been obtained almost under the neutral conditions. The above results suggests that IHA is a potentially efficient absorbent to purify water from the heavy metal contaminants.
Effect of pH values on the biohydrogen production from the enzymolysis liquid of the corn stalks via the photosynthetic bacteria
LU Chao-yang;WANG Yi;CAO Ming;LI Chang-ming;YANG Da-fei;ZHANG Quan-guo;This paper is aimed to explore the effect of pH value on the hydrogen-producing kinetics by photosynthetic bacteria from the enzymolysis liquid from the cornstalks.Taking the dry weight of biomass as assessment indicators,we have studied the effect of the different pH values on the growth of photosynthetic bacteria.In proceeding with our research,we have done the regression simulation for the growth of photosynthetic bacteria and photosynthetic bacteria hydrogen production from the enzymolysis liquid of corn stalks by using the logistic model and MMF model.As a result,we have found the effect of the different pH values on the features of hydrogen production kinetics and the growth conditions of photosynthetic bacteria,which implies that different pH values tend to affect the growth kinetics of photosynthetic bacteria differently whereas the hydrogen production kinetics of corn stalks enzymolysis liquid significantly.We have also found that pH value has a significant impact on the growth of the photosynthetic bacteria and hydrogen production process.For example,with the increase of pH,the photosynthetic bacterial biomass tends to increase in a proportional manner.When the pH value is 8,the maximum of the photosynthetic bacterial biomass turns to be0.543 7 g/L with the best time for inoculation being 84-96 h.What is more,the hydrogen production of photosynthetic bacteria tends to increase first and then decrease with the growth of pH value.When the pH value becomes 6,it has been found that the rate and capacity of the hydrogen production may reach its maximum degree,29.72 mL/(L·h) and 168.96 mL respectively.The results of our experiment can help to provide a scientific reference for further improvement of the enzymatic saccharification of the corn stalks on the photosynthetic hydrogen production theoretically and technically.
Analysis of the mechanism of the road traffic accidents in-situ and the future research trends
LI Shu-qing;PENG You-lang;XIAO Li-ying;MENG Si-meng;WANG Peng;XU Ji-peng;School of Traffic & Transportation,Chongqing Jiaotong University;In order to disclose the essential regularities behind the traffic accidents and enhance the theoretical research system for preventing from and reducing the traffic accidents to the minimum point,the present paper aims to make a systematic exploration and summary of traffic accidents based on the study of the frequency of road traffic accidents and the increasingly traffic safety problems both at home and abroad.The research goals of the paper include(1) The study of the mechanism of the incidence of traffic accidents,the judgment and the actual manipulative measures to deal with the likely accidents while driving;(2)The mechanism of the traffic interactive flow distribution,overspeeding and speed deviation;(3) The mechanism of the drivers' competence for the drivers to control the accidents and the actual driving demands of the actual driving tasks;(4) The mechanism of the likeliness between the drivers' misbehaviors and the accidental driving mis-operation caused by the judgment gap due to the road traffic system factors and the drivers' driving intentions;(5) The mechanism of the accident tree,based on the analysis of the problems and inefficiency in the research into the road traffic accidents in situ and in the future in the traffic accident exploration.The future research trends may include(1)Exploring the novel classification methods of the influential indices that may account for such traffic accidents;(2) An depth-analysis in the coupled interactions between the influential factors and the actual rates of road traffic accidents;(3) Seeking the key and decisive factors(quantified indices) that may account for the traffic accidents;(4) Establishing the theoretical relationship models and quantitative models which can reflect the influence of the coupled interactions of the key and decisive factors on road traffic safety;(5) Conducting researches on the mechanisms of the traffic accidents on the basis of ergonomics;(6) Doing researches on the mechanisms of the traffic accidents based on the actual accident data.
Impact or lessons of the accidents on the miners' reckless behaviors based on the social cognition theory
YANG Zhen-hong;LI Pan;WANG Wen-jie;The given paper intends to propose a research approach from the past behaviors or known as the scenario-cognitive factor-behaviors based on the experimental framework of the social cognitive science. As a matter of fact,the paper has brought about the safety attitude and risk perception of the post-dependent variables of the accident experiences through 11 hypotheses of the safety atmosphere of the regulation variables gained from the accidents due to the miners' reckless behaviors based on the research results of the scholars both at home and abroad. And,then,we have also figured out a hypothetical model of the corresponding influential factors on the miners ' behaviors under the regulation of the safety atmosphere. Furthermore,via the measurement scale of other scholars as reference,we have also compiled the related variables in reference to the measuring scales of the other related mining enterprises as well as through a questionnaire survey of 308 front-line workmen of the metal-mining enterprises of Shaanxi and Gansu to verify the hypothesis model we have prepared by using the software known as SPSS 22. 0. The actual goals of the questionnaire survey are also to examine and prove the internal consistency,the reliability,the convergence validity and the correlation volubility of the questionnaire with the software known as AMOS 18. 0,so as to confirm the accident originality and their negative impact of the miners ' reckless behaviors through potential perception of the risk and safety consequences with the entire effect of accident lessons on their reckless behaviors being at about-0. 404. However,as the results of our investigation,all the impact on the unintentional reckless behaviors tends to be merely-0. 263,of which the risk awareness just plays an intermediary inclination to the accident consequence and their attitude towards the likely safety events,whereas the safety attitude tends to function intermediately in the risk perception and the reckless behaviors. Besides,the paper can also be used to serve as a tool of linear hierarchical regression to enhance the workmen's awareness of the significance for positive enhancement of the accident risks. Among the above regulatory effects,enhance of the safety atmosphere can be said to play the key role in regulating the impact of the safety awareness attitude.
Prediction and factor analysis of air quality in Mianyang using XGBoost and SHAP
WEI Jiafang;WEI Rongsheng;ZHAO Tianci;FAN Xinjian;JI Penghui;ZENG Junxiang;ZHANG Yiwen;As urbanization accelerates, air pollution has become an increasingly prominent issue. Accurately predicting the Air Quality Index(AQI) is crucial for early pollution warning and effective scientific governance. This paper aims to develop a high-precision and interpretable AQI prediction model to identify the key driving factors behind air pollution and provide decision support for environmental management. Utilizing daily average air quality monitoring data from Mianyang City spanning 2013 to 2024, we analyze the temporal variation trends of various pollutant concentrations. Spearman correlation analysis was employed to uncover the quantitative relationship between the dependent variable(AQI) and independent variables. The Extreme Gradient Boosting(XGBoost) algorithm was utilized to develop the AQI prediction model, while the Shapley Additive Explanations(SHAP) method was applied to analyze the interpretability of the model's outputs, quantifying the contribution of each pollution factor to the AQI. Furthermore, comparative experiments were conducted with other models to evaluate the performance of the XGBoost model. The results indicate that the coefficient of determination(R2) for the XGBoost model was 0.99 for the training set and 0.96 for the test set, with a Mean Squared Error(MSE) of 50.47. The prediction performance of the XGBoost model outperforms that of other machine learning models. SHAP analysis further revealed that ozone(O3), fine particulate matter(PM2.5), and inhalable particulate matter(PM10) are the primary factors influencing changes in AQI, with their combined contribution exceeding 80%. Additionally, significant differences in influence weights among various pollutants were observed during periods of high pollution incidence compared to those with good air quality, indicating a more pronounced synergistic effect among pollutants in high-concentration scenarios. The XGBoost-SHAP model proposed in this paper effectively enhances the accuracy of air quality predictions and facilitates in-depth analyses of pollution causes. These research findings provide a scientific basis for precise control and time-segmented regulation of urban air pollution.
Coupling coordination development and spatial differentiation of economy-energy-ecology-science and technology in the Yellow River basin
ZHANG Xuewei;DU Fenglian;SHEN Xiaoyan;ZONG Gang;It is of great strategic significance to promote ecological protection and high-quality development of the Yellow River basin. Based on the concept of high-quality development, a comprehensive evaluation index system of economy-energy-ecology-science and technology was constructed, and the comprehensive index was measured by entropy method. Then, the coupling coordination model was introduced to measure the coupling coordination degree of economy-energy-ecology-science and technology in the Yellow River Basin from 2005 to 2019. The spatial and temporal pattern of coupling coordination degree was analyzed by ArcGIS method, and the spatial econometric model was constructed to further reveal its influencing factors. The results show that :(1) From the comprehensive evaluation results, the development level of economy-energy-ecology-science and technology of most provinces in the Yellow River basin showed a fluctuating upward trend, and the increase of the comprehensive development level of Henan and Sichuan was greater than that of other provinces.(2) From the perspective of coupling coordination degree, the coupling coordination degree of economy-energy-ecology-science and technology in the Yellow River basin was at a medium-high level, and the coupling coordination degree of most provinces showed a trend of fluctuation and rise. After 2007, the mean value of the coupling coordination degree was above 0.5, indicating that the coupling coordination degree in the Yellow River basin was at a medium-high level, and most provinces in the Yellow River basin showed an upward trend.(3) Under the spatial weight, coupling coordination degree of economy-energy-ecology-science and technology in the Yellow River had significant positive spatial spillover effects. Among the target level indicators, ecology and energy were important factors affecting the coupling and coordinated development of the Yellow River basin. Among the first-level indicators, economic quality, energy consumption, environmental governance, environmental damage, and scientific and technological output had relatively greater impacts on the coupling coordination.
Analysis of carbon emissions and carbon reduction rffect of 3D printing buildings based on LCA method
MENG Qingcheng;HU Lei;LI Mingjian;WAN Da;WU Haojie;QI Xin;Aiming at the evaluation of carbon emission and carbon reduction effect of 3D printed buildings, the life cycle evaluation method is adopted to define the calculation boundary and calculation model of carbon emission of 3D printing buildings. The carbon emission of 3D-printed buildings in the materialization stage is compared with that of traditional buildings and general green buildings. The quantitative analysis shows the following results: First, in the materialization stages of 3D printing construction and traditional construction, and general green construction, the carbon emissions of building materials account for about 90% of the total carbon emissions. Among the carbon emissions of building materials, the carbon emissions of concrete are dominant, accounting for about 70%-80%. 3D printing of special concrete can effectively reduce the carbon emission per cubic meter of concrete by 10%-30% by adding fly ash, silica fume, and other materials instead of some cement, which has a good carbon reduction effect. Secondly, the total amount of carbon emissions generated during the material transportation and construction of the 3D printing construction mode is reduced by 28.02% and 27.84% respectively compared with the traditional construction mode and the general green construction mode. Finally, in the building materialization stage, the total carbon emissions of 3D printing construction are reduced by 15.97% and 8.78% compared with those of traditional construction and general green construction, respectively, which indicates that 3D printing construction can not only reduce the carbon of traditional construction but also reduce the carbon of general green construction using low-carbon concrete. It is concluded that the way of carbon reduction in the construction industry should focus on new building materials and new construction technologies, while the characteristics of low-carbon concrete, “template-free” construction, and high mechanization of building 3D printing technology meet this requirement, and the carbon reduction effect is remarkable, which is conducive to promoting the carbon reduction action in the construction industry.
Bayesian network evaluation of road network resilience in the Guangdong-Hong Kong-Macao Greater Bay Area city cluster
ZHAO Rongguo;YANG Jinchen;LI Jie;ZHOU Suhua;With the further increase of the urbanization rate in China, the resilience of urban road networks has attracted increasing attention. In this paper, a resilience evaluation model for the urban road network is developed based on the Bayesian network model. Then, taking the city cluster in the mainland of the Guangdong-Hong Kong-Macao Greater Bay Area as an example, the road network resilience of nine cities in the mainland part of the Guangdong-Hong Kong-Macao Greater Bay Area during the period 2000-2019 is evaluated. According to the resilience function, the functional layer is constructed based on the four indicators as resilience, stability, reconfigurability, and recovery, the nine factors as stability, variability, maintainability, reliability, serviceability, safety, robustness, repairability, and adaptability are selected to establish the performance layer, and the nine factors as passenger volume, number of buses, road area rate, number of cabs, number of traffic fatalities, public transportation investment, number of buses per 10 000 people, number of road transportation employees, and road area per capita are selected to build the factor layer. The results show that Shenzhen's road network resilience index is the highest at 60%, while Zhongshan's is the lowest at 43%. The road network resilience of Guangzhou, Shenzhen, Zhuhai, and Dongguan has been growing steadily during the period 2000-2019, while that of Foshan, Huizhou, Zhongshan, Jiangmen, and Zhaoqing fluctuates slightly. The urban road network resilience does not always increase with the GDP growth but is also related to per capita GDP. The sensitivity analysis for the elements of function layer, performance layer and factor layer in the Bayesian network model shows that the road network reconfigurability, road network reliability, and number of traffic fatalities are the most influential factors on road network resilience in their respective layers, and strengthening the links between the central city and other cities can improve the resilience of urban road networks. The research results of this paper can provide some technical references for the improvement and resilience growth of the transportation network function in the Guangdong-Hong Kong-Macao Greater Bay Area city cluster.
Safety risk assessment of prefabricated building construction based on IM-FCM
WANG Qiankun;ZHU Ke;GUO Peiwen;GUO Zeng;ZHANG Biao;Aiming at the problem of insufficient dynamic interpretation capability of existing safety risk assessment methods, this research aims to accurately evaluate the safety risk of prefabricated building construction and improve the level of construction safety management. To achieve this purpose, a Level 2 Risk Assessment architecture of work breakdown structure and risk breakdown structure is used to establish a safety risk assessment index system for prefabricated building construction. A Combination Ordered Weighted Averaging(C-OWA) operator to quantify the subjective scores of experts is introduced to construct a coupling interaction matrix. Using the fusion model of the interaction matrix and a fuzzy cognitive map, identification of key risks and prediction of safety evolutional trends can be obtained, which is verified by an empirical analysis of safety risk levels in a project in Wuhan City, China. The assessment results indicate that: this project shows high risk overall, which is almost in line with the actual situation of the project. With the interactive coupling and evolution of construction safety risk, the risk assessment coefficient is found to be increased by 10.28%, and the risk rises from Level Ⅲ to Ⅱ, indicating the probability of safety accidents increases. This result requires implementing dynamic risk early warning in the whole construction process. The risk-related risk factors with a high degree of importance warrant are primarily controlled, including “defects occur to vertical or horizontal component supporting systems”, “quality control and safety risks caused by improper treatment existing in construction sites”, “collision between hoist components which are not operated according to construction plan”, “improper protection in marginal operation, high latitude operation and climbing operation” and “operation errors caused by defects existing in cranes and hoisting equipment”. The fusion of the interaction matrix and a fuzzy cognitive map can obtain both the dynamic assessment of construction safety risks and the prediction of construction safety risk evolution from the temporal dimension. This quantitative method can largely reduce the subjectivity of risk assessment and improve the dynamic interpretation of the assessment model.
Dynamic risk assessment of gas leakage in urban utility based on Dynamic Bayesian Network
ZHANG Jixin;HUANG Dongyang;YOU Qiuju;KANG Jian;LIU Mengting;GUO Xiahui;To solve the problems of many risk factors and dynamic change of risk state with time in utility tunnel gas pipeline network system, a dynamic risk assessment method of gas leakage in urban utility tunnel based on Dynamic Bayesian Network(DBN) is proposed based on traditional fault tree and static Bayesian Network. Firstly, this paper analyzes and summarizes the main risk factors and different accident consequences that lead to the leakage of the utility tunnel gas pipeline network by using a Bow-Tie model. Then, the time factor is introduced and according to the mapping rules of the Fault Tree Analysis(FTA) model and the Dynamic Bayesian Network model of urban utility tunnel gas leakage is established. The prior probability of each basic event is determined by referring to the historical database and expert scoring, and the Leaky Noisy-or Gate model is introduced to improve the conditional probability table of the DBN. Finally, combined with GENIE software, the system model is solved by using the bidirectional reasoning function of the DBN model. The time series curve of gas leakage probability and accident consequence probability of a utility tunnel is obtained by case analysis, and the main risk sources leading to gas leakage are obtained by reverse reasoning. The results show that the gas leakage probability of the utility tunnel at the initial moment is 9.296×10-2, and the leakage probability will increase to 2.094×10-1 if the hidden dangers are not checked in time. Compared with the traditional buried gas pipeline, the detection and alarm devices and ventilation facilities of the pipe gallery are very important for the safe and reliable operation of the gas pipeline network in the utility tunnel, which requires regular inspection and daily maintenance. The research results can provide theoretical support for risk assessment and daily maintenance of utility tunnels.