Relationship between sea level change and a single climate indicator has been widely discussed.However,few studies focused on the relationship between monthly mean sea level(MMSL)and several key impact factors,includi...Relationship between sea level change and a single climate indicator has been widely discussed.However,few studies focused on the relationship between monthly mean sea level(MMSL)and several key impact factors,including CO_(2) concentration,sea ice area,and sunspots,on various time scales.In addition,research on the independent relationship between climate factors and sea level on various time scales is lacking,especially when the dependence of climate factors on Nino 3.4 is excluded.Based on this,we use wavelet coherence(WC)and partial wavelet coherence(PWC)to establish a relationship between MMSL and its influencing factors.The WC results show that the influence of climate indices on MMSL has strong regional characteristics.The significant correlation between Southern Hemisphere sea ice area and MMSL is opposite to that between Northern Hemisphere sea ice area and MMSL.The PWC results show that after removing the influence of Nino 3.4,the significant coherent regions of the Pacific Decadal Oscillation(PDO),Dipole Mode Index(DMI),Atlantic Multidecadal Oscillation(AMO),and Southern Oscillation Index(SOI)decrease to varying degrees on different time scales in different regions,demonstrating the influence of Nino 3.4.Our work emphasizes the interrelationship and independent relationship between MMSL and its influencing factors on various time scales and the use of PWC and WC to describe this relationship.The study has an important reference significance for selecting the best predictors of sea level change or climate systems.展开更多
Based on the annual sample data on food production in China since the reform and opening up,we select 8 main factors influencing the total food production( growing area,application rate of chemical fertilizer,effectiv...Based on the annual sample data on food production in China since the reform and opening up,we select 8 main factors influencing the total food production( growing area,application rate of chemical fertilizer,effective irrigation area,the affected area,total machinery power,food production cost index,food production price index,financial funds for supporting agriculture,farmers and countryside),and put them into categories of material input,resources and environment,and policy factors. Using the factor analysis,we carry out the multi-angle analysis of these typical influencing factors one by one through the time series trend chart. It is found that application rate of chemical fertilizer,the growing area of food crops and drought-affected area become the key factors affecting food production. On this basis,we set forth the corresponding recommendations for improving the comprehensive food production capacity.展开更多
China is witnessing a very complicated economic development environment.Migrant workers'working patterns will directly affect their income level and the realization of many economic and social development goals.Th...China is witnessing a very complicated economic development environment.Migrant workers'working patterns will directly affect their income level and the realization of many economic and social development goals.This paper collects relevant data from three places:Shanghai,Lanzhou and Chengdu for empirical research whose results show that determinants of migrant worker's willing working time in urban areas mainly include the“income-consumption difference”,“urban-rural consumption difference”and their“urban income and expenditure uncertainty”.These factors directly affect their effective working time in the city,and determine their choice of choosing corresponding work patterns.From the significant differences of these factors,we can see that migrant workers in China is still struggling to solve their material needs under the pressure of livelihood,and less attention is paid to their spiritual needs and the pursuit of quality of life.展开更多
The coupling model of major influence factors such state affecting the chloride diffusion process in concrete is as environmental relative humidity, load-induced crack and stress discussed. The probability distributio...The coupling model of major influence factors such state affecting the chloride diffusion process in concrete is as environmental relative humidity, load-induced crack and stress discussed. The probability distributions of the critical chloride concentration Cc, the chloride diffusion coefficient D, and the surface chloride concentration Cs were determined based on the collected natural exposure data. And the estimation of probability of corrosion initiation considering the coupling effects of influence factors is presented. It is found that the relative humidity and curing time are the most effective factors affecting the probability of corrosion initiation before and after 10 years of exposure time. At the same exposure time, the influence of load-induced crack and stress state on the probability of corrosion initiation is obvious, in which the effect of crack is the most one展开更多
The middle class in metropolitan Chinese cities has become an important social group. With the rapid development of urbanization and constant advancement of suburbanization, the middle class has increasingly come to i...The middle class in metropolitan Chinese cities has become an important social group. With the rapid development of urbanization and constant advancement of suburbanization, the middle class has increasingly come to influence city traffic. Research into middle-class commuting activities thus has practical significance for improving traffic congestion and reducing the commuting burden in metropolitan cities. Based on a dataset formed by 816 completed surveys, this paper analyzes the commuting mode, time and distance of middle-class residents in Guangzhou City using the descriptive statistical method. The results indicate that private cars are the main commuting mode, followed by public transport. Meanwhile, middle-class residents mainly undertake medium-short time and medium-short distance commuting. The study subsequently uses multilevel logistic regression and multiple linear regression models to analyze the factors that influence commuting mode choice, time and distance. The gender, age, number of family cars, housing source and jobs-housing balance are the most important factors influencing commuting mode choice; housing, population density, jobs-housing balance and commuting mode significantly affect commuting time; and transport accessibility, jobs-housing balance and commuting mode are the notable factors affecting commuting distance. Finally, this paper analyzes what is affecting the commuting activities of middle-class residents and determines the differences in commuting activity characteristics and influence factors between middle-class and ordinary residents. Policy suggestions to improve urban planning and urban management are also proposed.展开更多
Real-time electricity price( RTEP) influence factor extraction is essential to forecasting accurate power system electricity prices. At present,new electricity price forecasting models have been studied to improve pre...Real-time electricity price( RTEP) influence factor extraction is essential to forecasting accurate power system electricity prices. At present,new electricity price forecasting models have been studied to improve predictive accuracy,ignoring the extraction and analysis of RTEP influence factors. In this study,a correlation analysis method is proposed based on stochastic matrix theory.Firstly, an augmented matrix is formulated, including RTEP influence factor data and RTEP state data. Secondly, data correlation analysis results are obtained given the statistical characteristics of source data based on stochastic matrix theory.Mean spectral radius( MSR) is used as the measure of correlativity.Finally,the proposed method is evaluated in New England electricity markets and compared with the BP neural network forecasting method. Experimental results show that the extracted index system comprehensively generalizes RTEP influence factors,which play a significant role in improving RTEP forecasting accuracy.展开更多
Accurate and real-time passenger flow prediction of rail transit is an important part of intelligent transportation systems(ITS).According to previous studies,it is found that the prediction effect of a single model i...Accurate and real-time passenger flow prediction of rail transit is an important part of intelligent transportation systems(ITS).According to previous studies,it is found that the prediction effect of a single model is not good for datasets with large changes in passenger flow characteristics and the deep learning model with added influencing factors has better prediction accuracy.In order to provide persuasive passenger flow forecast data for ITS,a deep learning model considering the influencing factors is proposed in this paper.In view of the lack of objective analysis on the selection of influencing factors by predecessors,this paper uses analytic hierarchy processes(AHP)and one-way ANOVA analysis to scientifically select the factor of time characteristics,which classifies and gives weight to the hourly passenger flow through Duncan test.Then,combining the time weight,BILSTM based model considering the hourly travel characteristics factors is proposed.The model performance is verified through the inbound passenger flow of Ningbo rail transit.The proposed model is compared with many current mainstream deep learning algorithms,the effectiveness of the BILSTM model considering influencing factors is validated.Through comparison and analysis with various evaluation indicators and other deep learning models,the results show that the R2 score of the BILSTM model considering influencing factors reaches 0.968,and the MAE value of the BILSTM model without adding influencing factors decreases by 45.61%.展开更多
This study examined the impact of the operative and peri-operative factors on the long-term prognosis of patients with primary liver cancer undergoing hepatectomy. A total of 222 patients with primary liver cancer who...This study examined the impact of the operative and peri-operative factors on the long-term prognosis of patients with primary liver cancer undergoing hepatectomy. A total of 222 patients with primary liver cancer who underwent hepatectomy were followed up from January 1986 to December 2010 at Chinese PLA General Hospital. The post-operative complication rate was 14.0% for all cases, 13.7% for hepatocellular carcinoma(HCC), 10.0% for cholangiocarcinoma. The 1-, 3-, 5- and 10-year overall survival rates in patients with primary liver cancer after resection were 76.6%, 57.6%, 41.4%, and 21.0%. The survival rates were significantly higher in the HCC group than in the cholangiocarcinoma group(P=0.000), in the non-anatomical resection group than in the anatomical resection group(P=0.005), in the female group than in the male group(P=0.002), in patients receiving no blood transfusion than in those who were given intra-operative blood transfusion(P=0.000), in patients whose intra-operative blood loss was less than 400 m L than in those who intra-operatively lost more than 400 m L(P=0.000). No significant difference was found in the survival rate between the HBs Ag-positive group and the HBs Ag-negative group(P=0.532). Our study showed that anatomical resection, blood loss and blood transfusion were predictors of poor survival after hepatectomy for primary liver cancer patients, and concomitant hepatitis B virus infection bore no relation with the post-resection survival.展开更多
Based on imbibition replacement of shut-in well in tight oil reservoirs, this paper expounds the principle of saturation rebalancing during the shut-in process after fracturing, establishes an optimization method for ...Based on imbibition replacement of shut-in well in tight oil reservoirs, this paper expounds the principle of saturation rebalancing during the shut-in process after fracturing, establishes an optimization method for shut-in time after horizontal well volume fracturing with the goal of shortening oil breakthrough time and achieving rapid oil breakthrough, and analyzes the influences of permeability, porosity, fracture half-length and fracturing fluid volume on the shut-in time. The oil and water imbibition displacement in the matrix and fractures occurs during the shut-in process of wells after fracturing. If the shut-in time is too short, the oil-water displacement is not sufficient, and the oil breakthrough time is long after the well is put into production. If the shut-in time is too long, the oil and water displacement is sufficient, but the energy dissipation in the formation near the bottom of the well is severe, and the flowing period is short and the production is low after the well is put into production. A rational shut-in time can help shorten the oil breakthrough time, extend the flowing period and increase the production of the well. The rational shut-in time is influenced by factors such as permeability, porosity, fracture half-length and fracturing fluid volume. The shortest and longest shut-in times are negatively correlated with porosity, permeability, and fracture half-length, and positively correlated with fracturing fluid volume. The pilot test in tight oil horizontal wells in the Songliao Basin, NE China, has confirmed that the proposed optimization method can effectively improve the development effect of horizontal well volume fracturing.展开更多
随着电网换相型高压直流输电(line commutated converter based high voltage direct current, LCC-HVDC)技术的广泛应用,交直流混联电力系统的交互稳定性问题日益突出。首先基于状态空间平均法建立了考虑非线性换相重叠动态过程的LCC...随着电网换相型高压直流输电(line commutated converter based high voltage direct current, LCC-HVDC)技术的广泛应用,交直流混联电力系统的交互稳定性问题日益突出。首先基于状态空间平均法建立了考虑非线性换相重叠动态过程的LCC换流器传递函数模型。为适应愈加复杂的直流输电系统建模,提出利用模块化思想分别建立LCC-HVDC各子系统小信号模型,并推导了能反映交直流系统和换流器之间电气耦合特性的接口矩阵实现子系统连接,从而模块化建立精确且易于扩展的计及控制链路延时和锁相环输出相位波动的双端LCC-HVDC系统改进小信号模型。最后分析了控制系统参数和控制链路延时对系统小干扰稳定性的影响以及失稳模态的主导因素,揭示了双端LCC-HVDC系统交直流混合谐振机理及送受端交互影响具体过程。研究结果可以为系统参数设计、谐振抑制措施提供理论基础。展开更多
基金Supported by the National Key R&D Program of China (No.2021YFC3001000)the National Natural Science Foundation of China (Nos.U1911204,51861125203)。
文摘Relationship between sea level change and a single climate indicator has been widely discussed.However,few studies focused on the relationship between monthly mean sea level(MMSL)and several key impact factors,including CO_(2) concentration,sea ice area,and sunspots,on various time scales.In addition,research on the independent relationship between climate factors and sea level on various time scales is lacking,especially when the dependence of climate factors on Nino 3.4 is excluded.Based on this,we use wavelet coherence(WC)and partial wavelet coherence(PWC)to establish a relationship between MMSL and its influencing factors.The WC results show that the influence of climate indices on MMSL has strong regional characteristics.The significant correlation between Southern Hemisphere sea ice area and MMSL is opposite to that between Northern Hemisphere sea ice area and MMSL.The PWC results show that after removing the influence of Nino 3.4,the significant coherent regions of the Pacific Decadal Oscillation(PDO),Dipole Mode Index(DMI),Atlantic Multidecadal Oscillation(AMO),and Southern Oscillation Index(SOI)decrease to varying degrees on different time scales in different regions,demonstrating the influence of Nino 3.4.Our work emphasizes the interrelationship and independent relationship between MMSL and its influencing factors on various time scales and the use of PWC and WC to describe this relationship.The study has an important reference significance for selecting the best predictors of sea level change or climate systems.
基金Supported by Humanities and Social Sciences Fund of the Ministry of Education(12YJC790094)Tianjin Philosophy and Social Science Planning Project(TJYY13-028TJLJ13-011)
文摘Based on the annual sample data on food production in China since the reform and opening up,we select 8 main factors influencing the total food production( growing area,application rate of chemical fertilizer,effective irrigation area,the affected area,total machinery power,food production cost index,food production price index,financial funds for supporting agriculture,farmers and countryside),and put them into categories of material input,resources and environment,and policy factors. Using the factor analysis,we carry out the multi-angle analysis of these typical influencing factors one by one through the time series trend chart. It is found that application rate of chemical fertilizer,the growing area of food crops and drought-affected area become the key factors affecting food production. On this basis,we set forth the corresponding recommendations for improving the comprehensive food production capacity.
基金The National Social Science Fund of China:Study on the Impact of Migrant Workers'Migrant Birds Work Mode and Employment Security in the Process of Urbanization(15XJL011)。
文摘China is witnessing a very complicated economic development environment.Migrant workers'working patterns will directly affect their income level and the realization of many economic and social development goals.This paper collects relevant data from three places:Shanghai,Lanzhou and Chengdu for empirical research whose results show that determinants of migrant worker's willing working time in urban areas mainly include the“income-consumption difference”,“urban-rural consumption difference”and their“urban income and expenditure uncertainty”.These factors directly affect their effective working time in the city,and determine their choice of choosing corresponding work patterns.From the significant differences of these factors,we can see that migrant workers in China is still struggling to solve their material needs under the pressure of livelihood,and less attention is paid to their spiritual needs and the pursuit of quality of life.
基金Project(50925829) supported by the National Science Fund for Distinguished Young Scholars of ChinaProject(50908148) supported by the National Natural Science Foundation of ChinaProjects(2009-K4-23,2010-11-33) supported by the Research of Ministry of Housing and Urban Rural Development of China
文摘The coupling model of major influence factors such state affecting the chloride diffusion process in concrete is as environmental relative humidity, load-induced crack and stress discussed. The probability distributions of the critical chloride concentration Cc, the chloride diffusion coefficient D, and the surface chloride concentration Cs were determined based on the collected natural exposure data. And the estimation of probability of corrosion initiation considering the coupling effects of influence factors is presented. It is found that the relative humidity and curing time are the most effective factors affecting the probability of corrosion initiation before and after 10 years of exposure time. At the same exposure time, the influence of load-induced crack and stress state on the probability of corrosion initiation is obvious, in which the effect of crack is the most one
基金Under the auspices of National Natural Science Foundation of China(No.41271182)
文摘The middle class in metropolitan Chinese cities has become an important social group. With the rapid development of urbanization and constant advancement of suburbanization, the middle class has increasingly come to influence city traffic. Research into middle-class commuting activities thus has practical significance for improving traffic congestion and reducing the commuting burden in metropolitan cities. Based on a dataset formed by 816 completed surveys, this paper analyzes the commuting mode, time and distance of middle-class residents in Guangzhou City using the descriptive statistical method. The results indicate that private cars are the main commuting mode, followed by public transport. Meanwhile, middle-class residents mainly undertake medium-short time and medium-short distance commuting. The study subsequently uses multilevel logistic regression and multiple linear regression models to analyze the factors that influence commuting mode choice, time and distance. The gender, age, number of family cars, housing source and jobs-housing balance are the most important factors influencing commuting mode choice; housing, population density, jobs-housing balance and commuting mode significantly affect commuting time; and transport accessibility, jobs-housing balance and commuting mode are the notable factors affecting commuting distance. Finally, this paper analyzes what is affecting the commuting activities of middle-class residents and determines the differences in commuting activity characteristics and influence factors between middle-class and ordinary residents. Policy suggestions to improve urban planning and urban management are also proposed.
基金National Natural Science Foundation of China(No.61701104)the “13th Five Year Plan” Research Foundation of Jilin Provincial Department of Education,China(No.JJKH2017018KJ)
文摘Real-time electricity price( RTEP) influence factor extraction is essential to forecasting accurate power system electricity prices. At present,new electricity price forecasting models have been studied to improve predictive accuracy,ignoring the extraction and analysis of RTEP influence factors. In this study,a correlation analysis method is proposed based on stochastic matrix theory.Firstly, an augmented matrix is formulated, including RTEP influence factor data and RTEP state data. Secondly, data correlation analysis results are obtained given the statistical characteristics of source data based on stochastic matrix theory.Mean spectral radius( MSR) is used as the measure of correlativity.Finally,the proposed method is evaluated in New England electricity markets and compared with the BP neural network forecasting method. Experimental results show that the extracted index system comprehensively generalizes RTEP influence factors,which play a significant role in improving RTEP forecasting accuracy.
基金supported by the Program of Humanities and Social Science of Education Ministry of China(Grant No.20YJA630008)the Ningbo Natural Science Foundation of China(Grant No.202003N4142)+1 种基金the Natural Science Foundation of Zhejiang Province,China(Grant No.LY20G010004)the K.C.Wong Magna Fund in Ningbo University,China.
文摘Accurate and real-time passenger flow prediction of rail transit is an important part of intelligent transportation systems(ITS).According to previous studies,it is found that the prediction effect of a single model is not good for datasets with large changes in passenger flow characteristics and the deep learning model with added influencing factors has better prediction accuracy.In order to provide persuasive passenger flow forecast data for ITS,a deep learning model considering the influencing factors is proposed in this paper.In view of the lack of objective analysis on the selection of influencing factors by predecessors,this paper uses analytic hierarchy processes(AHP)and one-way ANOVA analysis to scientifically select the factor of time characteristics,which classifies and gives weight to the hourly passenger flow through Duncan test.Then,combining the time weight,BILSTM based model considering the hourly travel characteristics factors is proposed.The model performance is verified through the inbound passenger flow of Ningbo rail transit.The proposed model is compared with many current mainstream deep learning algorithms,the effectiveness of the BILSTM model considering influencing factors is validated.Through comparison and analysis with various evaluation indicators and other deep learning models,the results show that the R2 score of the BILSTM model considering influencing factors reaches 0.968,and the MAE value of the BILSTM model without adding influencing factors decreases by 45.61%.
文摘This study examined the impact of the operative and peri-operative factors on the long-term prognosis of patients with primary liver cancer undergoing hepatectomy. A total of 222 patients with primary liver cancer who underwent hepatectomy were followed up from January 1986 to December 2010 at Chinese PLA General Hospital. The post-operative complication rate was 14.0% for all cases, 13.7% for hepatocellular carcinoma(HCC), 10.0% for cholangiocarcinoma. The 1-, 3-, 5- and 10-year overall survival rates in patients with primary liver cancer after resection were 76.6%, 57.6%, 41.4%, and 21.0%. The survival rates were significantly higher in the HCC group than in the cholangiocarcinoma group(P=0.000), in the non-anatomical resection group than in the anatomical resection group(P=0.005), in the female group than in the male group(P=0.002), in patients receiving no blood transfusion than in those who were given intra-operative blood transfusion(P=0.000), in patients whose intra-operative blood loss was less than 400 m L than in those who intra-operatively lost more than 400 m L(P=0.000). No significant difference was found in the survival rate between the HBs Ag-positive group and the HBs Ag-negative group(P=0.532). Our study showed that anatomical resection, blood loss and blood transfusion were predictors of poor survival after hepatectomy for primary liver cancer patients, and concomitant hepatitis B virus infection bore no relation with the post-resection survival.
基金Supported by China National Major Project of Science and Technology(2016ZX05046-004)PetroChina Major Project of Science and Technology(2017B-4905)PetroChina Jilin Oilfield Company Major Project of Science and Technology(JY21A2-12).
文摘Based on imbibition replacement of shut-in well in tight oil reservoirs, this paper expounds the principle of saturation rebalancing during the shut-in process after fracturing, establishes an optimization method for shut-in time after horizontal well volume fracturing with the goal of shortening oil breakthrough time and achieving rapid oil breakthrough, and analyzes the influences of permeability, porosity, fracture half-length and fracturing fluid volume on the shut-in time. The oil and water imbibition displacement in the matrix and fractures occurs during the shut-in process of wells after fracturing. If the shut-in time is too short, the oil-water displacement is not sufficient, and the oil breakthrough time is long after the well is put into production. If the shut-in time is too long, the oil and water displacement is sufficient, but the energy dissipation in the formation near the bottom of the well is severe, and the flowing period is short and the production is low after the well is put into production. A rational shut-in time can help shorten the oil breakthrough time, extend the flowing period and increase the production of the well. The rational shut-in time is influenced by factors such as permeability, porosity, fracture half-length and fracturing fluid volume. The shortest and longest shut-in times are negatively correlated with porosity, permeability, and fracture half-length, and positively correlated with fracturing fluid volume. The pilot test in tight oil horizontal wells in the Songliao Basin, NE China, has confirmed that the proposed optimization method can effectively improve the development effect of horizontal well volume fracturing.
文摘随着电网换相型高压直流输电(line commutated converter based high voltage direct current, LCC-HVDC)技术的广泛应用,交直流混联电力系统的交互稳定性问题日益突出。首先基于状态空间平均法建立了考虑非线性换相重叠动态过程的LCC换流器传递函数模型。为适应愈加复杂的直流输电系统建模,提出利用模块化思想分别建立LCC-HVDC各子系统小信号模型,并推导了能反映交直流系统和换流器之间电气耦合特性的接口矩阵实现子系统连接,从而模块化建立精确且易于扩展的计及控制链路延时和锁相环输出相位波动的双端LCC-HVDC系统改进小信号模型。最后分析了控制系统参数和控制链路延时对系统小干扰稳定性的影响以及失稳模态的主导因素,揭示了双端LCC-HVDC系统交直流混合谐振机理及送受端交互影响具体过程。研究结果可以为系统参数设计、谐振抑制措施提供理论基础。