Evaluation of Airport Size and Delay Causal Factor Effects on Delay Propagation Dissipation

Author(s):  
Stephanie Atallah ◽  
Susan Hotle

The International Civil Aviation Organization identifies departure and arrival punctuality as on-time key performance indicators. However, these metrics assume a flight’s delay is a result of either the origin or destination airport, providing limited information on where delay should be mitigated in the U.S. National Airspace System (NAS). This study evaluates the relationship between delay propagation magnitude, delay causal factor, airport size, and charged facility (airport or Air Route Traffic Control Center), to examine if certain delays take longer to dissipate. First, using flights from July 2018, results show that most delay propagation chains originate at large-hub airports. However, these delays were the quickest to recover. Second, this study presents a regression model, predicting total propagated delay using fixed effects based on the weather region where the original delay occurred. Each additional flight affected by downstream delay adds 18.7 min on average to total arrival delay in a propagation chain. Additionally, if weather was the original causal factor, total propagated delay increased by 11.6 min compared with non-weather delays. Lastly, this study compares delay propagation in July 2018 and July 2020. Results show uneven impacts of the coronavirus disease 2019 (COVID-19) across the large-hub airports. Some of the investigated airports did not witness large improvements in average delay per delayed flight, warranting further research in the future. While delay and delay propagation have not been completely eradicated in the NAS during the COVID-19 pandemic, findings suggest that both have significantly declined on average.

Author(s):  
Sehchang Hah ◽  
Ben Willems ◽  
Gary Mueller ◽  
Daniel R. Johnson ◽  
Kenneth Schulz ◽  
...  

The National Airspace System suffers from a reduction in airport throughput or even closure when weather or traffic volume constrains arrival or departure gates to and from the Terminal Radar Approach Control (TRACON) facilities. To alleviate this, the Federal Aviation Administration introduced the Integrated Arrival and Departure Control Services (IADCS) concept that would extend terminal separations and procedures to the adjacent Air Route Traffic Control Center (ARTCC) sectors for more flexible traffic. It proposes the use of resectorization, bidirectional gates, bidirectional routes, and Air Traffic Control assigned routes. We evaluated them in the human-in-the-loop high-fidelity experiment and collected objective and subjective data. Our results clearly showed that all IADCS procedures except the vertically separated/bidirectional gate procedure were more effective than the Baseline condition that controllers currently use in the field. We conjecture the vertically separated/bidirectional gate procedure requires more complex perceptual and cognitive processes than the other procedures.


Sensors ◽  
2021 ◽  
Vol 21 (11) ◽  
pp. 3658
Author(s):  
Qingfeng Zhu ◽  
Sai Ji ◽  
Jian Shen ◽  
Yongjun Ren

With the advanced development of the intelligent transportation system, vehicular ad hoc networks have been observed as an excellent technology for the development of intelligent traffic management in smart cities. Recently, researchers and industries have paid great attention to the smart road-tolling system. However, it is still a challenging task to ensure geographical location privacy of vehicles and prevent improper behavior of drivers at the same time. In this paper, a reliable road-tolling system with trustworthiness evaluation is proposed, which guarantees that vehicle location privacy is secure and prevents malicious vehicles from tolling violations at the same time. Vehicle route privacy information is encrypted and uploaded to nearby roadside units, which then forward it to the traffic control center for tolling. The traffic control center can compare data collected by roadside units and video surveillance cameras to analyze whether malicious vehicles have behaved incorrectly. Moreover, a trustworthiness evaluation is applied to comprehensively evaluate the multiple attributes of the vehicle to prevent improper behavior. Finally, security analysis and experimental simulation results show that the proposed scheme has better robustness compared with existing approaches.


2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Hui Meng ◽  
Yunping Zhou ◽  
Yunxia Jiang

AbstractObjectivesThe results of existing studies on bisphenol A (BPA) and puberty timing did not reach a consensus. Thereby we performed this meta-analytic study to explore the association between BPA exposure in urine and puberty timing.MethodsMeta-analysis of the pooled odds ratios (OR), prevalence ratios (PR) or hazards ratios (HR) with 95% confidence intervals (CI) were calculated and estimated using fixed-effects or random-effects models based on between-study heterogeneity.ResultsA total of 10 studies involving 5621 subjects were finally included. The meta-analysis showed that BPA exposure was weakly associated with thelarche (PR: 0.96, 95% CI: 0.93–0.99), while no association was found between BPA exposure and menarche (HR: 0.99, 95% CI: 0.89–1.12; OR: 1.02, 95% CI: 0.73–1.43), and pubarche (OR: 1.00, 95% CI: 0.79–1.26; PR: 1.00, 95% CI: 0.95–1.05).ConclusionsThere was no strong correlation between BPA exposure and puberty timing. Further studies with large sample sizes are needed to verify the relationship between BPA and puberty timing.


2019 ◽  
Vol 286 (1902) ◽  
pp. 20190359 ◽  
Author(s):  
Martin Kolk ◽  
Kieron Barclay

We examine the relationship between cognitive ability and childbearing patterns in contemporary Sweden using administrative register data. The topic has a long history in the social sciences and has been the topic of a large number of studies, many reporting a negative gradient between intelligence and fertility. We link fertility histories to military conscription tests with intelligence scores for all Swedish men born 1951–1967. We find a positive relationship between intelligence scores and fertility, and this pattern is consistent across the cohorts we study. The relationship is most pronounced for the transition to a first child, and men with the lowest categories of IQ scores have the fewest children. Using fixed effects models, we additionally control for all factors that are shared by siblings, and after such adjustments, we find a stronger positive relationship between IQ and fertility. Furthermore, we find a positive gradient within groups at different levels of education. Compositional differences of this kind are therefore not responsible for the positive gradient we observe—instead, the relationship is even stronger after controlling for both educational careers and parental background factors. In our models where we compare brothers to one another, we find that, relative to men with IQ 100, the group with the lowest category of cognitive ability have 0.56 fewer children, and men with the highest category have 0.09 more children.


2021 ◽  
pp. 000765032110193
Author(s):  
Shawn Pope ◽  
Jimi Kim

According to surveys of companies, branding is one of the main objectives of their corporate social responsibility (CSR). With advantageous data from Brand Finance, we address three contextual factors that may condition the relationship between CSR and brand value. First, we hypothesize that the relationship between CSR and brand value obtains across major world regions and industrial sectors (“the convergence thesis”). Second, we hypothesize that the relationship has weakened with time, as companies have had increasing difficulty using CSR to differentiate their brands in a sea of CSR-espousing competitors (“the crowding out thesis”). Third, we hypothesize that the relationship between CSR and brand value is weaker where a brand’s identity is different from that of its corporate owner, which may make it difficult for observers to readily link (corporate-level) CSR with its potential (lower level) brand beneficiaries (“the identity-match thesis”). We support these hypotheses with random-effects, fixed-effects, and instrumental-variable regressions before ending with contributions, limitations, implications, and potential next steps.


2018 ◽  
Vol 2018 ◽  
pp. 1-7
Author(s):  
Shangwen Yang ◽  
Jingting Zhang ◽  
Ping Chen ◽  
Yongjie Yan

To allocate the en-routes and slots resource to the flights with collaborative decision-making, a multiobjective 0-1 integer programming model was proposed. According to different demands from air traffic control departments, airlines, and passengers, efficiency, equity, and effectiveness principles of collaborative decision-making were considered. With the aim to minimize the total flight delay costs, the total number of turning points, and average delay time of passengers, the effectiveness constraints were achieved. The algorithm was designed to solve the model on the basis of the objective method, and Lingo11 and MatlabR2007b were applied in numerical tests. To test how well the model works in real world, a numerical test was performed based on the simulated data of a civil en-route. Test results show that, compared with the traditional strategy of first come first served, the model gains better effect. The superiority of the model was verified.


2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Abbas Koolivand ◽  
Mahdi Salehi ◽  
Meysam Arabzadeh ◽  
Hassan Ghodrati

Purpose This paper aims to assess the relationship between a knowledge-based economy and fraudulent financial reporting. Design/methodology/approach The study is descriptive-correlation based on published information from enlisted firms on the Tehran Stock Exchange during 2013–2019 with a sample of 178 firms (1,246 observations). The method used for hypothesis testing is linear regression using the panel data. Findings The results show that a knowledge-based economy is associated negatively and significantly with financial reporting. Moreover, robust testing has also examined the hypotheses (including fixed effects, OLS and t + 1) that confirmed the study’s preliminary results. Originality/value As the study was carried out in the emergent financial markets, like Iran, to figure out the relationship between knowledge-based economy and financial reporting, it can provide helpful information for the practitioners in this field.


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