This study investigates the ultimate load-bearing capacity of rigid two-way concrete pavements placed on conventional and reinforced soil embankments using upper-bound limit analysis (UBLA). In the presence of the median strip, upper-bound solutions of rigid pavements resting on reinforced embankments did not draw much attention from previous researchers. Therefore, a rigorous UBLA is performed, adopting the multi-block failure mechanism for the intended purpose. The true upper-bound solution is achieved by satisfying the conditions of geometric compatibility and kinematic admissibility. The effects of the proximity of dual carriageways and embankment slopes on the load-bearing capacity of pavements are expressed in relation to interaction factors. The critical spacing beyond which the proximity effect ceases to exist is estimated for different slope angles of the embankment. A parametric investigation is performed to understand the influence of various soil parameters, embankment geometry, and layers of reinforcement. A notable improvement in the performance of two closely spaced rigid pavements can be observed by providing additional layers of reinforcement. The current outcomes are sensible and match well with the existing investigations.
{"title":"Ultimate Load-Bearing Capacity of Rigid Two-Way Pavements Placed on Geosynthetic-Supported Soil Embankment","authors":"Debashis Manna, Gunasekaran Santhoshkumar, Priyanka Ghosh","doi":"10.1177/03611981231193408","DOIUrl":"https://doi.org/10.1177/03611981231193408","url":null,"abstract":"This study investigates the ultimate load-bearing capacity of rigid two-way concrete pavements placed on conventional and reinforced soil embankments using upper-bound limit analysis (UBLA). In the presence of the median strip, upper-bound solutions of rigid pavements resting on reinforced embankments did not draw much attention from previous researchers. Therefore, a rigorous UBLA is performed, adopting the multi-block failure mechanism for the intended purpose. The true upper-bound solution is achieved by satisfying the conditions of geometric compatibility and kinematic admissibility. The effects of the proximity of dual carriageways and embankment slopes on the load-bearing capacity of pavements are expressed in relation to interaction factors. The critical spacing beyond which the proximity effect ceases to exist is estimated for different slope angles of the embankment. A parametric investigation is performed to understand the influence of various soil parameters, embankment geometry, and layers of reinforcement. A notable improvement in the performance of two closely spaced rigid pavements can be observed by providing additional layers of reinforcement. The current outcomes are sensible and match well with the existing investigations.","PeriodicalId":23279,"journal":{"name":"Transportation Research Record","volume":"86 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135980658","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-11DOI: 10.1177/03611981231194626
Wencui Yang, Mostafa Jafarzadehfadaki, Xiang Yan, Xilei Zhao, Xia Jin, Daniel Frolich, Virginia P. Sisiopiku
The rapid growth of shared e-scooters around the world creates an interest and a need to understand who uses shared e-scooters, trip patterns, and modal shift impacts. To shed light on these questions, this study conducted an online survey ( N = 1498) to collect information on shared e-scooter use in four U.S. cities: Birmingham, AL, Washington D.C., Los Angeles, CA, and Miami, FL. The paper provides a comprehensive view of shared e-scooter use in different cities and reveals the similarities and differences in e-scooter users’ socioeconomic characteristics. Furthermore, the results of a binary logistic model show the impact of socioeconomic and travel modal choice factors on predicting shared e-scooter usage. The findings suggest that male, younger, and more affluent users who live in smaller households owning fewer vehicles are more likely to use shared e-scooter services. The relationships between income level, race/ethnicity, or e-scooter ownership and the usage of shared e-scooters are not statistically significant. The McFadden’s R 2 of the binary logistic regression model indicates an excellent fit. The results also show that compared with non-users, shared e-scooter users tend to assess travel cost as more important and travel safety as less important in their mode choice. The findings from this work can help city planners, policymakers, and other micromobility stakeholders in their efforts to promote the adoption of shared e-scooters and improve on deployment practices of shared e-scooters at their locations.
{"title":"Shared E-Scooter User Characteristics and Usage Patterns across Four U.S. Cities","authors":"Wencui Yang, Mostafa Jafarzadehfadaki, Xiang Yan, Xilei Zhao, Xia Jin, Daniel Frolich, Virginia P. Sisiopiku","doi":"10.1177/03611981231194626","DOIUrl":"https://doi.org/10.1177/03611981231194626","url":null,"abstract":"The rapid growth of shared e-scooters around the world creates an interest and a need to understand who uses shared e-scooters, trip patterns, and modal shift impacts. To shed light on these questions, this study conducted an online survey ( N = 1498) to collect information on shared e-scooter use in four U.S. cities: Birmingham, AL, Washington D.C., Los Angeles, CA, and Miami, FL. The paper provides a comprehensive view of shared e-scooter use in different cities and reveals the similarities and differences in e-scooter users’ socioeconomic characteristics. Furthermore, the results of a binary logistic model show the impact of socioeconomic and travel modal choice factors on predicting shared e-scooter usage. The findings suggest that male, younger, and more affluent users who live in smaller households owning fewer vehicles are more likely to use shared e-scooter services. The relationships between income level, race/ethnicity, or e-scooter ownership and the usage of shared e-scooters are not statistically significant. The McFadden’s R 2 of the binary logistic regression model indicates an excellent fit. The results also show that compared with non-users, shared e-scooter users tend to assess travel cost as more important and travel safety as less important in their mode choice. The findings from this work can help city planners, policymakers, and other micromobility stakeholders in their efforts to promote the adoption of shared e-scooters and improve on deployment practices of shared e-scooters at their locations.","PeriodicalId":23279,"journal":{"name":"Transportation Research Record","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135981587","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-07DOI: 10.1177/03611981231193410
Zhihui Chen, Hao Xu, Junxuan Zhao, Hongchao Liu
Cities worldwide are striving to find more efficient approaches to address the prevalent parking challenges in urban areas. A key aspect of achieving an optimal parking environment is the collection of curbside parking data, which enables informed decision-making and effective management of on-street parking spaces. This study proposes a solution for curbside parking monitoring and data collection using roadside LiDAR systems. By leveraging laser beam variation detection, this solution can extract essential information about parking usage. Unlike existing solutions, such as imagery or embedded sensor-based monitoring, our solution offers portability and ease of deployment for short-term or long-term curbside parking data collection. Additionally, the LiDAR sensor captures only three-dimensional data and is independent of illumination conditions, ensuring stable operation throughout the day while safeguarding privacy by not capturing imagery. These features align with the requirements of city agencies for parking data collection. The workflow follows a simple trend without the need for complex training, as typically seen in machine learning-based methods, and instead relies on parameter tuning based on real-world environmental factors. To validate the effectiveness of our method, we collected curbside parking data for five days at a midtown traffic junction with eight parking spaces. Manual validation confirmed a 95% match between identified parking events and observed data across different time periods. The study further presents parking statistics based on the identified events, revealing crucial insights about parking usage in the study area.
{"title":"Curbside Parking Monitoring With Roadside LiDAR","authors":"Zhihui Chen, Hao Xu, Junxuan Zhao, Hongchao Liu","doi":"10.1177/03611981231193410","DOIUrl":"https://doi.org/10.1177/03611981231193410","url":null,"abstract":"Cities worldwide are striving to find more efficient approaches to address the prevalent parking challenges in urban areas. A key aspect of achieving an optimal parking environment is the collection of curbside parking data, which enables informed decision-making and effective management of on-street parking spaces. This study proposes a solution for curbside parking monitoring and data collection using roadside LiDAR systems. By leveraging laser beam variation detection, this solution can extract essential information about parking usage. Unlike existing solutions, such as imagery or embedded sensor-based monitoring, our solution offers portability and ease of deployment for short-term or long-term curbside parking data collection. Additionally, the LiDAR sensor captures only three-dimensional data and is independent of illumination conditions, ensuring stable operation throughout the day while safeguarding privacy by not capturing imagery. These features align with the requirements of city agencies for parking data collection. The workflow follows a simple trend without the need for complex training, as typically seen in machine learning-based methods, and instead relies on parameter tuning based on real-world environmental factors. To validate the effectiveness of our method, we collected curbside parking data for five days at a midtown traffic junction with eight parking spaces. Manual validation confirmed a 95% match between identified parking events and observed data across different time periods. The study further presents parking statistics based on the identified events, revealing crucial insights about parking usage in the study area.","PeriodicalId":23279,"journal":{"name":"Transportation Research Record","volume":"2677 1","pages":"824 - 838"},"PeriodicalIF":1.7,"publicationDate":"2023-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45716909","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-09DOI: 10.1177/03611981221140377
W. Williams, Sana Moran, E. Marx
The purpose of this project was to design and test a new Alaska multi-state 2-tube bridge rail meeting the safety-performance evaluation guidelines included in the American Association of State Highway and Transportation Officials (AASHTO) Manual for Assessing Safety Hardware (MASH), Second Edition 2016. The new 2-tube bridge rail designed and tested for this project was crash tested in accordance with MASH Test Level 4 (TL-4). Three crash tests were performed. The new bridge rail is 38 in. tall from the top of asphalt overlay and anchors to a 10 in. high by 18 in. wide curb. The curb was cast on top of a 35 ¾ in. wide deck cantilever that varied in thickness from 6 in. at the extreme field side edge to 12 in. at the exterior girder element. The posts were spaced on 10 ft centers. The posts were anchored to the concrete curb and deck using four 7/8 in. diameter A449 anchor bolts. The two-tube rail elements consisted of two HSS7 × 5 × 3/8 tubular elements. The calculated strength of the design was 77 kip at a height of 30 in. The bridge rail was considered acceptable for strength as per the AASHTO Load and Resistance Factor Design (LRFD) Section 13 Bridge Design Specifications. A test specimen of the bridge rail was constructed and crash tested per MASH TL-4. The new two-tube bridge rail met all the performance requirements of MASH TL-4. Details of the design and testing of the new bridge rail are provided in this paper.
{"title":"Design and Full-Scale Testing of New MASH Test Level 4 (TL-4) Alaska 2-Tube Bridge Rail","authors":"W. Williams, Sana Moran, E. Marx","doi":"10.1177/03611981221140377","DOIUrl":"https://doi.org/10.1177/03611981221140377","url":null,"abstract":"The purpose of this project was to design and test a new Alaska multi-state 2-tube bridge rail meeting the safety-performance evaluation guidelines included in the American Association of State Highway and Transportation Officials (AASHTO) Manual for Assessing Safety Hardware (MASH), Second Edition 2016. The new 2-tube bridge rail designed and tested for this project was crash tested in accordance with MASH Test Level 4 (TL-4). Three crash tests were performed. The new bridge rail is 38 in. tall from the top of asphalt overlay and anchors to a 10 in. high by 18 in. wide curb. The curb was cast on top of a 35 ¾ in. wide deck cantilever that varied in thickness from 6 in. at the extreme field side edge to 12 in. at the exterior girder element. The posts were spaced on 10 ft centers. The posts were anchored to the concrete curb and deck using four 7/8 in. diameter A449 anchor bolts. The two-tube rail elements consisted of two HSS7 × 5 × 3/8 tubular elements. The calculated strength of the design was 77 kip at a height of 30 in. The bridge rail was considered acceptable for strength as per the AASHTO Load and Resistance Factor Design (LRFD) Section 13 Bridge Design Specifications. A test specimen of the bridge rail was constructed and crash tested per MASH TL-4. The new two-tube bridge rail met all the performance requirements of MASH TL-4. Details of the design and testing of the new bridge rail are provided in this paper.","PeriodicalId":23279,"journal":{"name":"Transportation Research Record","volume":"2677 1","pages":"1 - 8"},"PeriodicalIF":1.7,"publicationDate":"2023-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49291514","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-07DOI: 10.1177/03611981231182963
Hannah King, Jacob L. Wasserman, Brian D. Taylor
The COVID-19 pandemic upended transit use, finance, and management. To investigate these effects two years into the pandemic, we conducted 21 semi-structured interviews with senior managers at transit agencies in the most populous U.S. state, California. We found that the pandemic generated many operational and managerial challenges for transit agencies. Ridership plummeted, then slowly recovered, but is still well below pre-pandemic levels at most agencies. Commuter trips to and from major job centers were especially slow to return. In response to decreased demand, public health concerns, and uncertain finances, many agencies cut services and spending early on. As a result, fare revenues declined, in some cases precipitously. However, federal pandemic relief funds proved essential in filling budgetary gaps, stabilizing finances, preventing layoffs, and maintaining services. Other transit subsidies mostly bounced back robustly. Our interviews suggest that, though California transit agencies experimented with free fares, few fareless programs were made permanent. Their challenges include considerable uncertainty associated with future travel demand, looming financial shortfalls at systems that formerly had high farebox recovery and are still drawing on federal pandemic funds to backfill their fare revenue losses, and protracted labor shortages of drivers and mechanics that are preventing many systems from providing desired levels of service.
{"title":"<i>Terra Incognita</i>: California Transit Agency Perspectives on Demand, Service, and Finance in the Age of COVID-19","authors":"Hannah King, Jacob L. Wasserman, Brian D. Taylor","doi":"10.1177/03611981231182963","DOIUrl":"https://doi.org/10.1177/03611981231182963","url":null,"abstract":"The COVID-19 pandemic upended transit use, finance, and management. To investigate these effects two years into the pandemic, we conducted 21 semi-structured interviews with senior managers at transit agencies in the most populous U.S. state, California. We found that the pandemic generated many operational and managerial challenges for transit agencies. Ridership plummeted, then slowly recovered, but is still well below pre-pandemic levels at most agencies. Commuter trips to and from major job centers were especially slow to return. In response to decreased demand, public health concerns, and uncertain finances, many agencies cut services and spending early on. As a result, fare revenues declined, in some cases precipitously. However, federal pandemic relief funds proved essential in filling budgetary gaps, stabilizing finances, preventing layoffs, and maintaining services. Other transit subsidies mostly bounced back robustly. Our interviews suggest that, though California transit agencies experimented with free fares, few fareless programs were made permanent. Their challenges include considerable uncertainty associated with future travel demand, looming financial shortfalls at systems that formerly had high farebox recovery and are still drawing on federal pandemic funds to backfill their fare revenue losses, and protracted labor shortages of drivers and mechanics that are preventing many systems from providing desired levels of service.","PeriodicalId":23279,"journal":{"name":"Transportation Research Record","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135903660","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-13DOI: 10.1177/03611981231184248
Jing Xu, Lu Dai, M. Hansen
This paper develops a model for quantifying the relationship between flight volume and its operational performance at the macro level and investigating whether there are any changes before, during, and after the pandemic. Inspired by the market basket concept from economics, we first calculate macro-level effective flight time (EFT) for the U.S. domestic flight market by constructing a flight basket. Semi-log-linear models are developed to formulate the relationship between the total number of flights and macro-level EFT and its components. The estimation results indicate that the total number of flights has a positive and significant impact on EFT and its components, with 29.244 min longer for the weighted EFT for the analysis period compared with a zero-traffic scenario. Further investigations into the post-pandemic period verify the performance of the model and indicate that deteriorating operational performance in this period, especially with regard to gate delay and taxi-in time, is not only a result of the recovery of the flight market.
{"title":"Flight Time and Flight Traffic Before, During, and After the Pandemic: What Has Changed?","authors":"Jing Xu, Lu Dai, M. Hansen","doi":"10.1177/03611981231184248","DOIUrl":"https://doi.org/10.1177/03611981231184248","url":null,"abstract":"This paper develops a model for quantifying the relationship between flight volume and its operational performance at the macro level and investigating whether there are any changes before, during, and after the pandemic. Inspired by the market basket concept from economics, we first calculate macro-level effective flight time (EFT) for the U.S. domestic flight market by constructing a flight basket. Semi-log-linear models are developed to formulate the relationship between the total number of flights and macro-level EFT and its components. The estimation results indicate that the total number of flights has a positive and significant impact on EFT and its components, with 29.244 min longer for the weighted EFT for the analysis period compared with a zero-traffic scenario. Further investigations into the post-pandemic period verify the performance of the model and indicate that deteriorating operational performance in this period, especially with regard to gate delay and taxi-in time, is not only a result of the recovery of the flight market.","PeriodicalId":23279,"journal":{"name":"Transportation Research Record","volume":" ","pages":""},"PeriodicalIF":1.7,"publicationDate":"2023-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48162595","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The enhancement of the efficiency of automated container terminals (ACTs) and promotion of energy saving and emission reduction have attracted increasing attention in the construction of resource-saving and environment-friendly ports. In this paper, an integrated scheduling optimization model of automatic guided vehicles (AGVs) and automatic stacking cranes (ASCs) is proposed to resolve the problem of long round trips and high energy consumption of ASCs in typical ACTs. The configurations of ACTs considering the landside buffer zone were analyzed. First, the feasibility of integrated scheduling when considering a landside buffer zone is introduced. The study also analyzes the problems that must be resolved for the integrated scheduling of AGVs and ASCs using the aforementioned layout handling technology. Subsequently, a multi-objective optimization model for the integrated scheduling of AGVs and ASCs considering the landside buffer zone was developed. In this model, the operations of AGVs and ASCs are divided into four categories: load transport, no-load transport, load/unload, and waiting. The objective of formulating the model was to minimize the makespan and total energy consumption. Finally, an improved non-dominated ranking genetic algorithm, NSGA-II, is employed to optimize the model. The results show that the makespan and total energy consumption of the integrated scheduling of AGVs and ASCs considering the landside and seaside buffer zones are better than those considering only the seaside buffer zone.
{"title":"Integrated Scheduling of Automatic Guided Vehicles and Automatic Stacking Cranes in Automated Container Terminals Considering Landside Buffer Zone","authors":"Jianguo Duan, Linzhe Li, Qinglei Zhang, Jiyun Qin, Ying Zhou","doi":"10.1177/03611981231168862","DOIUrl":"https://doi.org/10.1177/03611981231168862","url":null,"abstract":"The enhancement of the efficiency of automated container terminals (ACTs) and promotion of energy saving and emission reduction have attracted increasing attention in the construction of resource-saving and environment-friendly ports. In this paper, an integrated scheduling optimization model of automatic guided vehicles (AGVs) and automatic stacking cranes (ASCs) is proposed to resolve the problem of long round trips and high energy consumption of ASCs in typical ACTs. The configurations of ACTs considering the landside buffer zone were analyzed. First, the feasibility of integrated scheduling when considering a landside buffer zone is introduced. The study also analyzes the problems that must be resolved for the integrated scheduling of AGVs and ASCs using the aforementioned layout handling technology. Subsequently, a multi-objective optimization model for the integrated scheduling of AGVs and ASCs considering the landside buffer zone was developed. In this model, the operations of AGVs and ASCs are divided into four categories: load transport, no-load transport, load/unload, and waiting. The objective of formulating the model was to minimize the makespan and total energy consumption. Finally, an improved non-dominated ranking genetic algorithm, NSGA-II, is employed to optimize the model. The results show that the makespan and total energy consumption of the integrated scheduling of AGVs and ASCs considering the landside and seaside buffer zones are better than those considering only the seaside buffer zone.","PeriodicalId":23279,"journal":{"name":"Transportation Research Record","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135857666","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Terrorism, piracy, robbery, and cyber-threats on ships and at port facilities, as well as smuggling and drug trafficking through cargo and containers, are some of the international security problems for which national maritime security services must provide solutions. Cyber-attack is considered particularly important as it can be combined with all the other security vulnerabilities in the shipping industry. There is no extensive and in-depth literature for the risk acceptance criteria concerning maritime security. Basic information is drawn from other areas, such as civil aviation. It is necessary to standardize these criteria, as is the case with formal safety assessment, where practitioners know how to gather information, to make comparisons with previous experience, and to make decisions that are often based on experience from the past. The aim of the present study is to address the issue of maritime security through the development of a method applicable to the maritime industry that evaluates and manages maritime security-related risks. Security cost-benefit analysis and decision-making procedures will be required in the future. The proposed method uses the bow-tie diagram tool for the estimation of risk. A risk computation procedure is described after the application of a set of prevention barriers, which is based mainly on the accuracy of the definition of the probability and the contribution of each threat, as well as the accuracy of estimation of the effectiveness value of each prevention barrier for the same threat as defined by the user. Similarly, the risk computation for each consequence, after the application of a set of mitigation barriers, is based mainly on the accuracy of the definition of the risk value of each consequence as well as on the accuracy of the estimation of the effectiveness value of each mitigation barrier for the same consequence as defined by the user. The results of the risk computation appear in the bow-tie diagram providing a colored scheme of the risk values obtained for the top event and consequences after the introduction of the necessary prevention and mitigation barriers.Terrorism, piracy, robbery, cyber-threats, smuggling and drug trafficking etc., are some of the international security problems due to which the national maritime security services must provide solutions. There is no extensive literature for the risk acceptance criteria concerning maritime security and basic information is drawn from other areas. The aim of the proposed study is to develop a method applicable to the maritime industry that evaluates and manages maritime security related risks in a case of cyber-security. Security Cost-Benefit Analysis and Decision Making procedure will be required in the future. The proposed method uses the Bow-Tie diagram tool for the estimation of the risk. A risk computation procedure is described after the application of prevention barriers, which is based mainly on the accuracy of the definition of t
{"title":"Using a Proposed Risk Computation Procedure and Bow-Tie Diagram as a Method for Maritime Security Assessment","authors":"Panayiotis Papageorgiou, Zacharias Dermatis, Athanasios Anastasiou, Panagiotis Liargovas, Stratos Papadimitriou","doi":"10.1177/03611981231173641","DOIUrl":"https://doi.org/10.1177/03611981231173641","url":null,"abstract":"Terrorism, piracy, robbery, and cyber-threats on ships and at port facilities, as well as smuggling and drug trafficking through cargo and containers, are some of the international security problems for which national maritime security services must provide solutions. Cyber-attack is considered particularly important as it can be combined with all the other security vulnerabilities in the shipping industry. There is no extensive and in-depth literature for the risk acceptance criteria concerning maritime security. Basic information is drawn from other areas, such as civil aviation. It is necessary to standardize these criteria, as is the case with formal safety assessment, where practitioners know how to gather information, to make comparisons with previous experience, and to make decisions that are often based on experience from the past. The aim of the present study is to address the issue of maritime security through the development of a method applicable to the maritime industry that evaluates and manages maritime security-related risks. Security cost-benefit analysis and decision-making procedures will be required in the future. The proposed method uses the bow-tie diagram tool for the estimation of risk. A risk computation procedure is described after the application of a set of prevention barriers, which is based mainly on the accuracy of the definition of the probability and the contribution of each threat, as well as the accuracy of estimation of the effectiveness value of each prevention barrier for the same threat as defined by the user. Similarly, the risk computation for each consequence, after the application of a set of mitigation barriers, is based mainly on the accuracy of the definition of the risk value of each consequence as well as on the accuracy of the estimation of the effectiveness value of each mitigation barrier for the same consequence as defined by the user. The results of the risk computation appear in the bow-tie diagram providing a colored scheme of the risk values obtained for the top event and consequences after the introduction of the necessary prevention and mitigation barriers.Terrorism, piracy, robbery, cyber-threats, smuggling and drug trafficking etc., are some of the international security problems due to which the national maritime security services must provide solutions. There is no extensive literature for the risk acceptance criteria concerning maritime security and basic information is drawn from other areas. The aim of the proposed study is to develop a method applicable to the maritime industry that evaluates and manages maritime security related risks in a case of cyber-security. Security Cost-Benefit Analysis and Decision Making procedure will be required in the future. The proposed method uses the Bow-Tie diagram tool for the estimation of the risk. A risk computation procedure is described after the application of prevention barriers, which is based mainly on the accuracy of the definition of t","PeriodicalId":23279,"journal":{"name":"Transportation Research Record","volume":"87 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136017215","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Induced mutations are important for genetic research and breeding. Mutations induced by physical or chemical mutagenesis are usually heterozygous during the early generations. However, mutations must be fixed prior to phenotyping or field trials, which requires additional rounds of self-pollination. Microspore culture is an effective method to produce double-haploid (DH) plants that are fixed homozygotes. In this study, we conducted ethyl methanesulfonate (EMS)-induced mutagenesis of microspore cultures of barley (Hordeum vulgare) cultivar 'Hua30' and landrace 'HTX'. The EMS concentrations were negatively correlated with the efficiency of callus induction and the frequency of mutant plant regeneration. The two genotypes showed different regeneration efficiencies. The phenotypic variation of the regenerated M1 plants and the presence of genome-wide nucleotide mutations, revealed by whole-genome sequencing, highlight the utility of EMS-induced mutagenesis of isolated microspore cultures for developing DH mutants. Genome-wide analysis of the mutation frequency in the regenerated plants revealed that a considerable proportion of mutations resulted from microspore culture (somaclonal variation) rather than EMS-induced mutagenesis. In addition to producing a population of 1972 homozygous mutant lines that are available for future field trials, this study lays the foundation for optimizing the regeneration efficiency of DH plants and the richness of mutations (mainly by fine-tuning the mutagen dosage).
{"title":"Generating homozygous mutant populations of barley microspores by ethyl methanesulfonate treatment.","authors":"Linli Huang, Guangqi Gao, Congcong Jiang, Guimei Guo, Qiang He, Yingjie Zong, Chenghong Liu, Ping Yang","doi":"10.1007/s42994-023-00108-6","DOIUrl":"10.1007/s42994-023-00108-6","url":null,"abstract":"<p><p>Induced mutations are important for genetic research and breeding. Mutations induced by physical or chemical mutagenesis are usually heterozygous during the early generations. However, mutations must be fixed prior to phenotyping or field trials, which requires additional rounds of self-pollination. Microspore culture is an effective method to produce double-haploid (DH) plants that are fixed homozygotes. In this study, we conducted ethyl methanesulfonate (EMS)-induced mutagenesis of microspore cultures of barley (<i>Hordeum vulgare</i>) cultivar 'Hua30' and landrace 'HTX'. The EMS concentrations were negatively correlated with the efficiency of callus induction and the frequency of mutant plant regeneration. The two genotypes showed different regeneration efficiencies. The phenotypic variation of the regenerated M<sub>1</sub> plants and the presence of genome-wide nucleotide mutations, revealed by whole-genome sequencing, highlight the utility of EMS-induced mutagenesis of isolated microspore cultures for developing DH mutants. Genome-wide analysis of the mutation frequency in the regenerated plants revealed that a considerable proportion of mutations resulted from microspore culture (somaclonal variation) rather than EMS-induced mutagenesis. In addition to producing a population of 1972 homozygous mutant lines that are available for future field trials, this study lays the foundation for optimizing the regeneration efficiency of DH plants and the richness of mutations (mainly by fine-tuning the mutagen dosage).</p>","PeriodicalId":23279,"journal":{"name":"Transportation Research Record","volume":"1561 1","pages":"202-212"},"PeriodicalIF":3.6,"publicationDate":"2023-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10638298/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87861547","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-21DOI: 10.1177/03611981231179167
Rami Al-Sahar, Willem Klumpenhouwer, Amer Shalaby, Tamer El-Diraby
Measuring public opinion about the quality of transit services is a key factor in understanding and addressing customer dissatisfaction and increasing customer loyalty and ridership. Sentiment analysis using social media—in particular Twitter—is a relatively cheap and potentially powerful complement to traditional survey methods, which are expensive and limited in sample size. This study aims to evaluate customer response to the introduction of Calgary Transit’s MAX routes. We compared customer satisfaction expressed on Twitter with measured service reliability in the form of on-time performance. We also employed a qualitative research approach using content analysis from Twitter to gauge rider satisfaction over several service attributes before and after the service change. A transit-specific sentiment lexicon was developed to support this study using a hybrid approach. This lexicon outperformed generic sentiment lexicons traditionally used in transit studies with regard to both accuracy (18.4%) and F1-score (7.1%). We found that the overall perception of on-time performance from riders using Twitter was similar to the actual performance in the field. This was also observed for one individual route on which stops with poor schedule adherence were linked with negative feedback. This study concludes that combining customer-oriented measures from Twitter with operational-oriented ones would enable transit agencies to make better-informed decisions for planning and operational purposes.
{"title":"Using Twitter to Gauge Customer Satisfaction Response to a Major Transit Service Change in Calgary, Canada","authors":"Rami Al-Sahar, Willem Klumpenhouwer, Amer Shalaby, Tamer El-Diraby","doi":"10.1177/03611981231179167","DOIUrl":"https://doi.org/10.1177/03611981231179167","url":null,"abstract":"Measuring public opinion about the quality of transit services is a key factor in understanding and addressing customer dissatisfaction and increasing customer loyalty and ridership. Sentiment analysis using social media—in particular Twitter—is a relatively cheap and potentially powerful complement to traditional survey methods, which are expensive and limited in sample size. This study aims to evaluate customer response to the introduction of Calgary Transit’s MAX routes. We compared customer satisfaction expressed on Twitter with measured service reliability in the form of on-time performance. We also employed a qualitative research approach using content analysis from Twitter to gauge rider satisfaction over several service attributes before and after the service change. A transit-specific sentiment lexicon was developed to support this study using a hybrid approach. This lexicon outperformed generic sentiment lexicons traditionally used in transit studies with regard to both accuracy (18.4%) and F1-score (7.1%). We found that the overall perception of on-time performance from riders using Twitter was similar to the actual performance in the field. This was also observed for one individual route on which stops with poor schedule adherence were linked with negative feedback. This study concludes that combining customer-oriented measures from Twitter with operational-oriented ones would enable transit agencies to make better-informed decisions for planning and operational purposes.","PeriodicalId":23279,"journal":{"name":"Transportation Research Record","volume":"17 5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136296082","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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