Pub Date : 2014-09-01DOI: 10.5399/OSU/JTRF.53.3.4252
W. Fan
Car-sharing offers an environmentally sustainable, socially responsible and economically feasible mobility form in which a fleet of shared-use vehicles in a number of locations can be accessed and used by many people on as-needed basis at an hourly or mileage rate. To ensure its sustainability, car-sharing operators must be able to effectively manage dynamic and uncertain demands, and make the best decisions on strategic vehicle allocation and operational vehicle reallocation both in time and space to improve their profits while keeping costs under control. This paper develops a stochastic optimization method to optimize strategic allocation of vehicles for one-way carsharing systems under demand uncertainty. A multi-stage stochastic linear programming model is developed and solved for use in the context of car-sharing. A seven-stage experimental network study is conducted. Numerical results and computational insights are discussed.
{"title":"Optimizing Strategic Allocation of Vehicles for One-Way Car-sharing Systems Under Demand Uncertainty","authors":"W. Fan","doi":"10.5399/OSU/JTRF.53.3.4252","DOIUrl":"https://doi.org/10.5399/OSU/JTRF.53.3.4252","url":null,"abstract":"Car-sharing offers an environmentally sustainable, socially responsible and economically feasible mobility form in which a fleet of shared-use vehicles in a number of locations can be accessed and used by many people on as-needed basis at an hourly or mileage rate. To ensure its sustainability, car-sharing operators must be able to effectively manage dynamic and uncertain demands, and make the best decisions on strategic vehicle allocation and operational vehicle reallocation both in time and space to improve their profits while keeping costs under control. This paper develops a stochastic optimization method to optimize strategic allocation of vehicles for one-way carsharing systems under demand uncertainty. A multi-stage stochastic linear programming model is developed and solved for use in the context of car-sharing. A seven-stage experimental network study is conducted. Numerical results and computational insights are discussed.","PeriodicalId":405535,"journal":{"name":"Journal of the Transportation Research Forum","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132506001","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-09-01DOI: 10.5399/OSU/JTRF.53.3.4258
Ju Dong Park, W. Koo
The primary purpose of this study is to analyze air carriers’ behavior in capturing market share by examining the economic factors affecting passenger behavior toward air travel. This study also examines non-economic factors such as seasonality, unexpected events (9/11 attack), mergers, and trends. Because the airlines included in this study compete with each other, seemingly unrelated regression estimation (SURE) is used to estimate the parameters of the demand models which have correlated error terms. The economic and statistical relationship of the factors with air passenger miles provides valuable information to understand the nature of the demand for the U.S. air passenger industry. In examining demand determinants, this study concludes that air fare, income, seasonality, and mergers play significant roles in determining the demand for air passengers.
{"title":"The Magnitudes of Economic and Non-Economic Factors on the Demand for U.S. Domestic Air Travel","authors":"Ju Dong Park, W. Koo","doi":"10.5399/OSU/JTRF.53.3.4258","DOIUrl":"https://doi.org/10.5399/OSU/JTRF.53.3.4258","url":null,"abstract":"The primary purpose of this study is to analyze air carriers’ behavior in capturing market share by examining the economic factors affecting passenger behavior toward air travel. This study also examines non-economic factors such as seasonality, unexpected events (9/11 attack), mergers, and trends. Because the airlines included in this study compete with each other, seemingly unrelated regression estimation (SURE) is used to estimate the parameters of the demand models which have correlated error terms. The economic and statistical relationship of the factors with air passenger miles provides valuable information to understand the nature of the demand for the U.S. air passenger industry. In examining demand determinants, this study concludes that air fare, income, seasonality, and mergers play significant roles in determining the demand for air passengers.","PeriodicalId":405535,"journal":{"name":"Journal of the Transportation Research Forum","volume":"287 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124567112","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-09-01DOI: 10.5399/OSU/JTRF.53.3.4249
Tony Diana
Hierarchical linear models improve the measurement of performance when applied to a construct such as a metroplex. It compares the outcomes of a hierarchical linear model with those of a multiple regression model to evaluate whether meteorological conditions at individual airports and overall would explain variations in block delays. The study used the cases of the three largest airports in the DC Metroplex and concluded airborne delays had a significant random effect on block delays in spite of meteorological conditions at each airport. It pointed out that surface operations efficiency played a significant role in explaining variations in block delays.
{"title":"Measuring Performance at a Large Metropolitan Area: The Case of the DC (District of Columbia) Metroplex","authors":"Tony Diana","doi":"10.5399/OSU/JTRF.53.3.4249","DOIUrl":"https://doi.org/10.5399/OSU/JTRF.53.3.4249","url":null,"abstract":"Hierarchical linear models improve the measurement of performance when applied to a construct such as a metroplex. It compares the outcomes of a hierarchical linear model with those of a multiple regression model to evaluate whether meteorological conditions at individual airports and overall would explain variations in block delays. The study used the cases of the three largest airports in the DC Metroplex and concluded airborne delays had a significant random effect on block delays in spite of meteorological conditions at each airport. It pointed out that surface operations efficiency played a significant role in explaining variations in block delays.","PeriodicalId":405535,"journal":{"name":"Journal of the Transportation Research Forum","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134402668","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-06-01DOI: 10.5399/OSU/JTRF.53.2.4228
Zhenhua Chen, Nobuhiko Daito, Jonathon L. Gifford
Infrastructure public-private partnerships (“P3s”) have gained considerable recognition as useful policy tools for state and local governments to deliver critically needed infrastructure projects. The objective of this study is to empirically test one of the claims often made regarding states’ motivations for employing this procurement mechanism: P3s can help overcome fiscal constraints on state infrastructure investment. In addition, this study empirically analyzes how state P3 enabling legislation affects the behavior of both the public and private sectors. A regular logit model and a fixed effects logit panel model are employed to test the hypothesis that states with more severe fiscal constraints are more likely to seek P3s for highway infrastructure construction and finance. After controlling for such factors as state economic condition, legislative political affiliation, and highway travel demand, the empirical results indicate that states’ fiscal constraints are not associated with the propensity to use highway P3 projects.
{"title":"Do State Fiscal Constraints Affect Implementation of Highway Public-Private Partnerships? A Panel Fixed Logit Assessment","authors":"Zhenhua Chen, Nobuhiko Daito, Jonathon L. Gifford","doi":"10.5399/OSU/JTRF.53.2.4228","DOIUrl":"https://doi.org/10.5399/OSU/JTRF.53.2.4228","url":null,"abstract":"Infrastructure public-private partnerships (“P3s”) have gained considerable recognition as useful policy tools for state and local governments to deliver critically needed infrastructure projects. The objective of this study is to empirically test one of the claims often made regarding states’ motivations for employing this procurement mechanism: P3s can help overcome fiscal constraints on state infrastructure investment. In addition, this study empirically analyzes how state P3 enabling legislation affects the behavior of both the public and private sectors. A regular logit model and a fixed effects logit panel model are employed to test the hypothesis that states with more severe fiscal constraints are more likely to seek P3s for highway infrastructure construction and finance. After controlling for such factors as state economic condition, legislative political affiliation, and highway travel demand, the empirical results indicate that states’ fiscal constraints are not associated with the propensity to use highway P3 projects.","PeriodicalId":405535,"journal":{"name":"Journal of the Transportation Research Forum","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116711227","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-06-01DOI: 10.5399/OSU/JTRF.53.2.4234
B. Al-Omari, Khalid A. Ghuzlan, Lina B. Al-Helo
A total of 30 roundabouts with different dimensions and characteristics were selected from three cities in Jordan. The collected data included the approaching road free flow speed (FFS), area type, entry width, circulating roadway width, exit width, roundabout internal and external circle diameters, circulating roadway super elevation, entry deviation angle, and drive curve. The regression analysis showed that the entry width, internal circulating diameter, entry deviation angle, approaching FFS, and drive curve were significant in determining the average and 85th percentile roundabout circulating speed. The developed model was compared with other international models developed in the United States and Italy.
{"title":"Modeling Through Traffic Speed at Roundabouts Along Urban and Suburban Street Arterials","authors":"B. Al-Omari, Khalid A. Ghuzlan, Lina B. Al-Helo","doi":"10.5399/OSU/JTRF.53.2.4234","DOIUrl":"https://doi.org/10.5399/OSU/JTRF.53.2.4234","url":null,"abstract":"A total of 30 roundabouts with different dimensions and characteristics were selected from three cities in Jordan. The collected data included the approaching road free flow speed (FFS), area type, entry width, circulating roadway width, exit width, roundabout internal and external circle diameters, circulating roadway super elevation, entry deviation angle, and drive curve. The regression analysis showed that the entry width, internal circulating diameter, entry deviation angle, approaching FFS, and drive curve were significant in determining the average and 85th percentile roundabout circulating speed. The developed model was compared with other international models developed in the United States and Italy.","PeriodicalId":405535,"journal":{"name":"Journal of the Transportation Research Forum","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116081056","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-06-01DOI: 10.5399/OSU/JTRF.53.2.4231
J. Chi
This paper aims to improve understanding of the long-run impacts of the gross domestic product (GDP), real exchange rate, and the producer price index (PPI) on U.S.-Canada bilateral freight flows in a dynamic framework. Special attention is given to cross-border exports and imports by truck, rail, pipeline, and air. Using the fully modified ordinary least squares (FM-OLS) approach, the paper finds that the GDP of the importing country is a pronounced factor influencing U.S.- Canada cross-border trade, suggesting that economic growth of the country is a powerful driver in the relative intensity of bilateral freight flows. The real exchange rate tends to be positively associated with U.S. imports, but negatively associated with U.S. exports, indicating that the U.S. dollar depreciation against the Canadian dollar increases demand for U.S. commodities in Canada, but weakens demand for Canadian commodities in the United States. The long-run effects of the selected economic variables on cross-border exports and imports are found to vary by mode of transportation. The Canadian GDP has a positive and significant effect on U.S. freight exports by all transportation modes, but U.S. exports by pipeline are more sensitive to a change in Canadian GDP than U.S. exports by truck and rail. The findings in this paper provide important policy and managerial implications for cross-border transportation planning in the United States and Canada.
{"title":"Income and Exchange Rate Sensitivities of Cross-Border Freight Flows: Evidence from U.S.-Canada Exports and Imports by Truck, Rail, Air, and Pipeline","authors":"J. Chi","doi":"10.5399/OSU/JTRF.53.2.4231","DOIUrl":"https://doi.org/10.5399/OSU/JTRF.53.2.4231","url":null,"abstract":"This paper aims to improve understanding of the long-run impacts of the gross domestic product (GDP), real exchange rate, and the producer price index (PPI) on U.S.-Canada bilateral freight flows in a dynamic framework. Special attention is given to cross-border exports and imports by truck, rail, pipeline, and air. Using the fully modified ordinary least squares (FM-OLS) approach, the paper finds that the GDP of the importing country is a pronounced factor influencing U.S.- Canada cross-border trade, suggesting that economic growth of the country is a powerful driver in the relative intensity of bilateral freight flows. The real exchange rate tends to be positively associated with U.S. imports, but negatively associated with U.S. exports, indicating that the U.S. dollar depreciation against the Canadian dollar increases demand for U.S. commodities in Canada, but weakens demand for Canadian commodities in the United States. The long-run effects of the selected economic variables on cross-border exports and imports are found to vary by mode of transportation. The Canadian GDP has a positive and significant effect on U.S. freight exports by all transportation modes, but U.S. exports by pipeline are more sensitive to a change in Canadian GDP than U.S. exports by truck and rail. The findings in this paper provide important policy and managerial implications for cross-border transportation planning in the United States and Canada.","PeriodicalId":405535,"journal":{"name":"Journal of the Transportation Research Forum","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121416980","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-06-01DOI: 10.5399/OSU/JTRF.53.2.4225
M. Obeidat, M. Rys, E. Russell, Aditya Gund
Overhead guide sign visibility on highway, can be achieved either by illumination or by using retroreflective sheeting. Two surveys were sent to all U.S. departments of transportation, to determine the states’ policies for increasing overhead guide sign visibility. Results showed that 57% of states currently illuminate guide signs, and the most used retroreflective sheeting by states that do not illuminate signs is Diamond Grade for legend and High Intensity for background. Based on cost analysis, the LED light source and the High Intensity (types III and IV) retroreflective sheeting are the most cost-effective methods for increasing guide signs visibility.
{"title":"Determining Cost-Effective Policy for Visibility of Overhead Guide Signs on Highways","authors":"M. Obeidat, M. Rys, E. Russell, Aditya Gund","doi":"10.5399/OSU/JTRF.53.2.4225","DOIUrl":"https://doi.org/10.5399/OSU/JTRF.53.2.4225","url":null,"abstract":"Overhead guide sign visibility on highway, can be achieved either by illumination or by using retroreflective sheeting. Two surveys were sent to all U.S. departments of transportation, to determine the states’ policies for increasing overhead guide sign visibility. Results showed that 57% of states currently illuminate guide signs, and the most used retroreflective sheeting by states that do not illuminate signs is Diamond Grade for legend and High Intensity for background. Based on cost analysis, the LED light source and the High Intensity (types III and IV) retroreflective sheeting are the most cost-effective methods for increasing guide signs visibility.","PeriodicalId":405535,"journal":{"name":"Journal of the Transportation Research Forum","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124686131","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-06-01DOI: 10.5399/OSU/JTRF.53.2.4219
M. Jalayer, Huaguo Zhou, J. Gong, Shunfu Hu, M. Grinter
The implementation of the Highway Safety Manual (HSM) at the state level has the potential to allow transportation agencies to proactively address safety concerns. However, the widespread utilization of HSM faces significant barriers as many state departments of transportations (DOTs) do not have sufficient HSM-required highway inventory data. Many techniques have been utilized by state DOTs and local agencies to collect highway inventory data for other purposes. Nevertheless, it is unknown which of these methods or any combination of them is capable of efficiently collecting the required dataset while minimizing cost and safety concerns. The focus of this study is to characterize the capability of existing methods for collecting highway inventory data vital to the implementation of the recently published HSM. More specifically, this study evaluated existing highway inventory methods through a nationwide survey and a field trial of identified promising highway inventory data collection (HIDC) methods on various types of highway segments. A comparative analysis was conducted to present an example on how to incorporate weights provided by state DOT stakeholders to select the most suitable HIDC method for the specific purpose.
{"title":"A Comprehensive Assessment of Highway Inventory Data Collection Methods","authors":"M. Jalayer, Huaguo Zhou, J. Gong, Shunfu Hu, M. Grinter","doi":"10.5399/OSU/JTRF.53.2.4219","DOIUrl":"https://doi.org/10.5399/OSU/JTRF.53.2.4219","url":null,"abstract":"The implementation of the Highway Safety Manual (HSM) at the state level has the potential to allow transportation agencies to proactively address safety concerns. However, the widespread utilization of HSM faces significant barriers as many state departments of transportations (DOTs) do not have sufficient HSM-required highway inventory data. Many techniques have been utilized by state DOTs and local agencies to collect highway inventory data for other purposes. Nevertheless, it is unknown which of these methods or any combination of them is capable of efficiently collecting the required dataset while minimizing cost and safety concerns. The focus of this study is to characterize the capability of existing methods for collecting highway inventory data vital to the implementation of the recently published HSM. More specifically, this study evaluated existing highway inventory methods through a nationwide survey and a field trial of identified promising highway inventory data collection (HIDC) methods on various types of highway segments. A comparative analysis was conducted to present an example on how to incorporate weights provided by state DOT stakeholders to select the most suitable HIDC method for the specific purpose.","PeriodicalId":405535,"journal":{"name":"Journal of the Transportation Research Forum","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115482110","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-06-01DOI: 10.5399/OSU/JTRF.53.2.4237
Qi Zhao, Yap Yin Choo, T. Oum
This paper applies a stochastic cost frontier model to a panel of 54 major airports over 2002-2008 to examine how the two dominant governance forms of publicly owned airports in the United States and Canada, namely, operation and governance by a government (city, county, or state) branch, or by an airport authority, affect airport efficiency performance. Our key findings are (a) airports operated by an airport authority achieve higher cost efficiency (on average, 14% higher technical efficiency) than those operated by a government branch; (b) airports operated by a government branch have lower labor share than those operated by an airport authority; and (c) there is no statistically significant difference in the efficiency performance between airports operated by U.S. airport authorities and Canadian airport authorities.
{"title":"The Effect of Governance Forms on North American Airport Efficiency: A Comparative Analysis of Airport Authority vs. Government Branch","authors":"Qi Zhao, Yap Yin Choo, T. Oum","doi":"10.5399/OSU/JTRF.53.2.4237","DOIUrl":"https://doi.org/10.5399/OSU/JTRF.53.2.4237","url":null,"abstract":"This paper applies a stochastic cost frontier model to a panel of 54 major airports over 2002-2008 to examine how the two dominant governance forms of publicly owned airports in the United States and Canada, namely, operation and governance by a government (city, county, or state) branch, or by an airport authority, affect airport efficiency performance. Our key findings are (a) airports operated by an airport authority achieve higher cost efficiency (on average, 14% higher technical efficiency) than those operated by a government branch; (b) airports operated by a government branch have lower labor share than those operated by an airport authority; and (c) there is no statistically significant difference in the efficiency performance between airports operated by U.S. airport authorities and Canadian airport authorities.","PeriodicalId":405535,"journal":{"name":"Journal of the Transportation Research Forum","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116469942","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-06-01DOI: 10.5399/OSU/JTRF.53.2.4222
J. Carlton, M. Burris
Using National Household Travel Survey data and information collected from over 100 agencies, transportation-related taxation and expenditures were assigned to individual households in the Houston Core Based Statistical Area (CBSA). Using Gini Coefficients and Theil Indices, the research demonstrated that implementation of a Mileage Based User Fee (MBUF) would not have a pronounced effect on the current distribution of what households pay versus what they receive in transportation expenditures. The relative winners are rural and high income urban households, while the relative losers are all other urban households.
{"title":"Comprehensive Equity Analysis of Mileage-Based User Fees: Taxation and Expenditures for Roadways and Transit","authors":"J. Carlton, M. Burris","doi":"10.5399/OSU/JTRF.53.2.4222","DOIUrl":"https://doi.org/10.5399/OSU/JTRF.53.2.4222","url":null,"abstract":"Using National Household Travel Survey data and information collected from over 100 agencies, transportation-related taxation and expenditures were assigned to individual households in the Houston Core Based Statistical Area (CBSA). Using Gini Coefficients and Theil Indices, the research demonstrated that implementation of a Mileage Based User Fee (MBUF) would not have a pronounced effect on the current distribution of what households pay versus what they receive in transportation expenditures. The relative winners are rural and high income urban households, while the relative losers are all other urban households.","PeriodicalId":405535,"journal":{"name":"Journal of the Transportation Research Forum","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127931902","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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