107 results found
Teoh R, Stettler MEJ, Majumdar A, et al., 2019, A methodology to relate black carbon particle number and mass emissions, Journal of Aerosol Science, Vol: 132, Pages: 44-59, ISSN: 0021-8502
Black carbon (BC) particle number (PN) emissions from various sources contribute to the deterioration of air quality, adverse health effects, and anthropogenic climate change. This paper critically reviews different fractal aggregate theories to develop a new methodology that relates BC PN and mass concentrations (or emissions factors). The new methodology, named as the fractal aggregate (FA) model is validated with measurements from three different BC emission sources: an internal combustion engine, a soot generator, and two aircraft gas turbine engines at ground and cruise conditions. Validation results of the FA model show that R 2 values range from 0.44 to 0.95, while the Normalised Mean Bias is between −27.7% and +26.6%. The model estimates for aircraft gas turbines represent a significant improvement compared to previous methodologies used to estimate aviation BC PN emissions, which relied on simplified assumptions. Uncertainty and sensitivity analyses show that the FA model estimates have an asymmetrical uncertainty bound (−54%,+103%) at a 95% confidence interval for aircraft gas turbine engines and are most sensitive to uncertainties in the geometric standard deviation of the BC particle size distribution. Given the improved performance in estimating BC PN emissions from various sources, we recommend the implementation of the FA model in future health and climate assessments, where the impacts of PN are significant.
Kyriakidis M, Simanjuntak S, Singh S, et al., 2019, The indirect costs assessment of railway incidents and their relationship to human error - The case of Signals Passed at Danger, JOURNAL OF RAIL TRANSPORT PLANNING & MANAGEMENT, Vol: 9, Pages: 34-45, ISSN: 2210-9706
Koudis GS, Hu SJ, Majumdar A, et al., 2018, The impact of single engine taxiing on aircraft fuel consumption and pollutant emissions, Aeronautical Journal, Vol: 122, Pages: 1967-1984, ISSN: 0001-9240
Optimisation of aircraft ground operations to reduce airport emissions can reduce resultant local air quality impacts. Single engine taxiing (SET), where only half of the installed number of engines are used for the majority of the taxi duration, offers the opportunity to reduce fuel consumption, and emissions of NOX, CO and HC. Using 3510 flight data records, this paper develops a model for SET operations and presents a case study of London Heathrow, where we show that SET is regularly implemented during taxi-in. The model predicts fuel consumption and pollutant emissions with greater accuracy than previous studies that used simplistic assumptions. Without SET during taxi-in, fuel consumption and pollutant emissions would increase by up to 50%. Reducing the time before SET is initiated to the 25th percentile of recorded values would reduce fuel consumption and pollutant emissions by 7–14%, respectively, relative to current operations. Future research should investigate the practicalities of reducing the time before SET initialisation so that additional benefits of reduced fuel loadings, which would decrease fuel consumption across the whole flight, can be achieved.
Psyllou E, Majumdar A, Ochieng W, 2018, A Review of Navigation Involving General Aviation Pilots Flying under Visual Flight Rules, JOURNAL OF NAVIGATION, Vol: 71, Pages: 1130-1142, ISSN: 0373-4633
Sidiropoulos S, Majumdar A, Han K, 2018, A framework for the optimization of terminal airspace operations in Multi-Airport Systems, Transportation Research Part B: Methodological, Vol: 110, Pages: 160-187, ISSN: 0191-2615
Major cities like London, New York, and Tokyo are served by several airports, effectively creating a Multi-Airport System (MAS), or Metroplex. The operations of individual Metroplex airports are highly interdependent, rendering their efficient management rather difficult. This paper proposes a framework for the design of dynamic arrival and departure routes in MAS Terminal Maneuvering Areas, which fundamentally changes the operation in MAS airspaces for much improved efficiency when compared to the current situation. The framework consists of three components. The first presents a new procedure for characterizing dynamic arrival and departure routes based on the spatio-temporal distributions of flights. The second component is a novel Analytic Hierarchy Process (AHP) model for the prioritization of the dynamic routes, which takes into account a set of quantitative and qualitative attributes important for MAS operations. The third component is a priority-based method for the positioning of terminal waypoints as well as the design of three-dimensional, conflict-free terminal routes. Such a method accounts for the AHP-derived priorities while satisfying the minimal separation and aircraft maneuverability constraints. The developed framework is applied to a case study of the New York Metroplex, using aircraft trajectories during a heavy traffic period on typical day of operation in the New York Terminal Control Area in November 2011. The proposed framework is quantitatively assessed using the AirTOp fast-time simulation model. The results suggest significant improvements of the new design over the existing one, as measured by several key performance indicators such as travel distance, travel time, fuel burn, and controller workload. The operational feasibility of the framework is further validated qualitatively by subject matter experts from the Port Authority of New York and New Jersey, the operator of the New York Metroplex.
Majumdar A, Singh S, Kyriakidis M, 2018, Incorporating Human Reliability Analysis to enhance Maintenance Audits: The Case of Rail Bogie Maintenance, International Journal of Prognostics and Health Management, Vol: 8, ISSN: 2153-2648
Human error occurring during maintenance activities can reduce the safety and availability of equipments significantly. Identification of potential human errors, the cause of such errors and prediction the associate probability are important stages in order to manage the human errors. This paper investigates the probability of human error during maintenance of railway bogie. The case study examines technicians performing maintenance on the disc brake assembly unit, wheel set and bogie frame under various error producing conditions in a railway maintenance workshop in Luleå, Sweden. It implements Human Error Assessment and Reduction Technique (HEART) to determine the probability of human error occurring during each maintenance task, and applies fault tree analysis. The probability of the technician committing an error during maintenance of the disc brake assembly, wheel set and bogie frame is found to be 0.20, 0.039 and 0.021 respectively, with the human error probability for the entire bogie 0.24. Time pressures, ability to detect and perceive problems, over-riding information, the need to make decisions and mismatch between the operator and designer’s model turn out to be major contributors to human error. These findings can help maintenance management understand conditions and serve as an input to modify policies and guidelines for railway maintenance tasks.
Kyriakidis M, Majumdar A, Ochieng WY, 2017, The human performance railway operational index—a novel approach to assess human performance for railway operations, Reliability Engineering and System Safety, Vol: 170, Pages: 226-243, ISSN: 0951-8320
Human error and degraded human performance are associated with more than 80% of all railway accidents worldwide. Research on human performance and human reliability has highlighted the importance of the contextual factors associated with human errors, known as performance shaping factors (PSFs). A major shortcomings of current Human Reliability Analysis techniques, which employ qualitative and quantitative methods for assessing the human contribution to risk, lies with their little capability to model the dependencies among PSFs and to quantify their impact on human performance. This paper presents a novel approach to assess human performance accounting for the dependencies among the relevant PSFs, referred to as Human Performance Railway Operational Index (HuPeROI). The HuPeROI is developed on the integration of the Analytic Network Process and Success Likelihood Index Methodology, using the insights of 52 front-line, managerial and human factors railway personnel, and was demonstrated in three different types of railway operations: regional, high-speed and underground. Findings show that the HuPeROI can be efficiently used to assess operators’ performance as function of the quality of the relevant R-PSFs. Regulatory bodies and other stakeholders can implement the framework within their safety management systems to improve safety of railway operations.
Costa Teixeira Santos PL, Antunes Monteiro PA, Studic M, et al., 2017, A methodology used for the development of an Air Traffic Management functional system architecture, RELIABILITY ENGINEERING & SYSTEM SAFETY, Vol: 165, Pages: 445-457, ISSN: 0951-8320
Koudis GS, Hu SJ, North RJ, et al., 2017, The impact of aircraft takeoff thrust setting on NO<inf>X</inf> emissions, Journal of Air Transport Management, Vol: 65, Pages: 191-197, ISSN: 0969-6997
Reduced thrust takeoff has the potential to reduce aircraft-related NO X emissions at airports, however this remains to be investigated using flight data. This paper analyses the effect of takeoff roll thrust setting variability on the magnitude and spatial distribution of NO X emissions using high-resolution data records for 497 Airbus A319 activities at London Heathrow. Thrust setting varies between 67 and 97% of maximum, and aircraft operating in the bottom 10th percentile emit on average 514 g less NO X per takeoff roll (32% reduction) than the top 10th percentile, however this is dependent on takeoff roll duration. Spatial analysis suggests that peak NO X emissions, corresponding to the start of the takeoff roll, can be reduced by up to 25% by adopting reduced thrust takeoff activities. Furthermore, the length of the emission source also decreases. Consequently, the use of reduced thrust takeoff may enable improved local air quality at airports.
Ali BS, Ochieng WY, Majumdar A, 2017, ADS-B: Probabilistic Safety Assessment, JOURNAL OF NAVIGATION, Vol: 70, Pages: 887-906, ISSN: 0373-4633
Koudis GS, Hu J, Majumdar A, et al., 2017, Airport emissions reductions from reduced thrust takeoff operations, Transportation Research Part D: Transport and Environment, Vol: 52, Pages: 15-28, ISSN: 1879-2340
Given forecast aviation growth, many airports are predicted to reach capacity and require expansion. However, pressure to meet air quality regulations emphasises the importance of efficient ground-level aircraft activities to facilitate growth. Operational strategies such as reducing engine thrust setting at takeoff can reduce fuel consumption and pollutant emissions; however, quantification of the benefits and consistency of its use have been limited by data restrictions. Using 3,336 high-resolution flight data records, this paper analyses the impact of reduced thrust takeoff at London Heathrow. Results indicate that using reduced thrust takeoff reduces fuel consumption, nitrogen oxides (NOX) and black carbon (BC) emissions by 1.0-23.2%, 10.7-47.7%, and 49.0-71.7% respectively, depending on aircraft-engine combinations relative to 100% thrust takeoff. Variability in thrust settings for the same aircraft-engine combination and dependence on takeoff weight (TOW) is quantified. Consequently, aircraft-engine specific optimum takeoff thrust settings that minimise fuel consumption and pollutant emissions for different aircraft TOWs are presented. Further reductions of 1.9%, 5.8% and 6.5% for fuel consumption, NOX and BC emissions could be achieved, equating to reductions of approximately 0.4%, 3.5% and 3.3% in total ground level fuel consumption, NOX and BC emissions. These results quantify the contribution that reduced thrust operations offer towards achieving industry environmental targets and air quality compliance, and imply that the current implementation of reduced thrust takeoff at Heathrow is near optimal, considering operational and safety constraints.
Sidiropoulos S, Han K, Majumdar A, et al., 2016, Robust identification of air traffic flow patterns in Metroplex terminal areas under demand uncertainty, Transportation Research Part C - Emerging Technologies, Vol: 75, Pages: 212-227, ISSN: 0968-090X
Multi-Airport Systems (MAS), or Metroplexes, serve air traffic demand in cities with two or more airports. Due to the spatial proximity and operational interdependency of the airports, Metroplex airspaces are characterized by high complexity, and current system structures fail to provide satisfactory utilization of the available airspace resources. In order to support system-level design and management towards increased operational efficiency in such systems, an accurate depiction of major demand patterns is a prerequisite. This paper proposes a framework for the robust identification of significant air traffic flow patterns in Metroplex systems, which is aligned with the dynamic route service policy for the effective management of Metroplex operations. We first characterize deterministic demand through a spatio-temporal clustering algorithm that takes into account changes in the traffic flows over the planning horizon. Then, in order to handle uncertainties in the demand, a Distributionally Robust Optimization (DRO) approach is proposed, which takes into account demand variations and prediction errors in a robust way to ensure the reliability of the demand identification. The DRO-based approach is applied on pre-tactical (i.e. one-day planning) as well as operational levels (i.e. 2-h rolling horizon). The framework is applied to Time Based Flow Management (TBFM) data from the New York Metroplex. The framework and results are validated by Subject Matter Experts (SMEs).
Studic M, Majumdar A, Schuster W, et al., 2016, A systemic modelling of ground handling services using the functional resonance analysis method, TRANSPORTATION RESEARCH PART C-EMERGING TECHNOLOGIES, Vol: 74, Pages: 245-260, ISSN: 0968-090X
Pien KC, Han K, Majumdar A, A linear programming approach for system-optimal dynamic traffic assignment in the European Air Traffic Network, Transportation Research Board 96th Annual Meeting
Anvari B, Majumdar A, Ochieng W, Mixed traffic modelling involving pedestrian dynamics for integrated street designs: A review, PED2016: 8th International Conference on Pedestrian and Evacuation Dynamics
Sidiropoulos S, Han K, Majumdar A, et al., 2016, Identifying significant traffic flow patterns in Multi-Airport Systems Terminal Manoeuvring Areas under uncertainty, 16th AIAA Aviation Technology, Integration, and Operations Conference
Nascimento FAC, Majumdar A, Ochieng WY, et al., 2016, Fundamentals of safety management: The Offshore Helicopter Transportation System Model, Safety Science, Vol: 85, Pages: 194-204, ISSN: 0925-7535
Damy S, Majumdar A, Ochieng WY, 2016, GNSS-based High Accuracy Positioning for Railway Applications, 47th Annual Precise Time and Time Interval Systems and Applications Meeting (PTTI) / International Technical Meeting of the-Institute-of-Navigation, Publisher: Institute of Navigation, Pages: 1003-1014
The railway industry is facing a global increase in travel and freight demand, which requires extra capacity. Providing such capacity is limited by the current positioning systems used for railway traffic management. The past decade has seen a growing interest in GNSSbased positioning solutions for railway applications due to their global coverage, low cost and interoperability with existing systems. However, the railway operational environment presents a number of challenges to GNSS due to track side buildings, stations and tunnels which attenuate or block signals and generate multipath. This paper reviews the wide range of railway applications that can benefit from a GNSS-based enhanced positioning function, along with the existing requirements. It reviews the different positioning techniques that can be used and the different error sources the system has to deal with, including multipath. Finally it compares the effect of different multipath mitigation weighting techniques including elevation weighting, C/N0 weighting, residualbased weighting and multipath-based weighting. A novel adaptive weighting method based on the railway track geometry is introduced also and is compared to the current methods.
Nascimento FAC, Majumdar A, Ochieng WY, et al., 2015, Nighttime offshore helicopter operations: a survey of risk levels per phase of flight, flying recency requirement and visual approach technique, AERONAUTICAL JOURNAL, Vol: 119, Pages: 1475-1498, ISSN: 0001-9240
Tobaruela G, Schuster W, Majumdar A, et al., 2015, Framework to Assess an Area Control Centre's Operating Cost-efficiency: a Case Study, Journal of Navigation, Vol: 68, Pages: 1088-1104, ISSN: 1469-7785
Cost-efficiency is a crucial Key Performance Area (KPA) in today's Air Traffic Management (ATM) system. Traditionally, research has mainly focused on the airport domain, with little attention being paid to the operating cost-efficiency of Area Control Centres (ACCs). This paper addresses this shortcoming and develops a framework to assess the cost-efficiency of an ACC from an operational perspective. It investigates how the resources of an ACC are managed, from the start of the planning process to the day of operation. The framework develops new metrics to assess an ACC's performance. A case study is carried out on the Maastricht Upper Area Control (MUAC) centre. Results show that, despite being one of the most advanced ACCs in Europe, the human workforce is operating at only approximately 50% of their full capabilities.
Pien KC, Han K, Shang WL, et al., 2015, Robustness Analysis of the European Air Traffic Network, Transportmetrica A: Transport Science, Vol: 11, Pages: 772-792, ISSN: 2324-9943
The European air traffic network (ATN), consisting of a set of airports and area control cen- tres, is highly complex. The current indicator of its performance, air traffic flow management delays, is insufficient for planning and management purposes. Topological analysis of ATNs of this kind has highlighted betweenness centrality (BC) as an indicator of network robustness, although such an indicator assumes no knowledge of actual traffic flows and the network’s operational characteristics. This paper conducts topological and operational analyses of the European ATN in order to derive a more relevant and appropriate indicator of robustness. By applying a flow maximisation model to the network influenced by a range of capacity reductions at the local level, we propose a new index called the Relative Area Index (RAI). The RAI quantifies the importance of an individual node relevant to the performance of the entire network when it suffers from capacity reduction at a local scale. Air traffic data from three typical busy days in Europe are utilised to show that the RAI is more flexible and capable than BC in capturing the network impact of local capacity degradation. This index can be used to assess network robustness and provide a valuable tool for airspace managers and planners.
Ali BS, Ochieng WY, Schuster W, et al., 2015, A safety assessment framework for the Automatic Dependent Surveillance Broadcast (ADS-B) system, SAFETY SCIENCE, Vol: 78, Pages: 91-100, ISSN: 0925-7535
Kyriakidis M, Majumdar A, Ochieng WY, 2015, Data based framework to identify the most significant performance shaping factors in railway operations, SAFETY SCIENCE, Vol: 78, Pages: 60-76, ISSN: 0925-7535
Studic M, Majumdar A, 2015, Apron safety - A missing piece in the SESAR ConOps puzzle, Pages: 32-40
© 2015 ACM. The transition from the flight management to the trajectory management concept in Single European Sky Air Traffic Management (ATM) Research (SESAR) Concept of Operations (ConOps) led to the expansion in the boundary of the Air Traffic Management (ATM) system - to include the airport apron. Whilst SESAR recognises the importance of improving cost-effectiveness, efficiency, flexibility, predictability and punctuality of Ground Handling Services (GHS) on the apron within the context of 4D trajectory management and proposes automation in these Key Performance Areas (KPAs), safety on the apron is completely neglected. This paper analyses drivers of apron safety that are currently neither acknowledged nor addressed by the SESAR ConOps. The results of a survey carried out on 43 participants on 5 airports worldwide highlight the importance of organizational factors in improving safety of GHS on the apron.
Sidiropoulos S, Majumdar A, Han K, et al., 2015, A framework for the classification and prioritization of arrival and departure routes in Multi-Airport Systems Terminal Manoeuvring Areas, 15th AIAA Aviation Technology, Integration, and Operations Conference, Publisher: AIAA Aviation
Typically major cities (London, New York, Tokyo) are served by several airports effectively creating aMulti-Airport System or Metroplex. The operations of the Metroplex airports are highly dependent on oneanother, which renders their efficient management difficult. This paper proposes a framework for theprioritization of arrival and departure routes in Multi-Airport Systems Terminal Manoeuvring Areas. Theframework consists of three components. The first component presents a new procedure for clustering arrivaland departure flights into dynamic routes based on their temporal and spatial distributions through theidentification of the important traffic flow patterns throughout the day of operations. The second componentis a novel Analytic Hierarchy Process model for the prioritization of the dynamic routes, accounting for a setof quantitative and qualitative characteristics important for Multi-Airport Systems operations. The thirdcomponent is a priority-based model for the facility location of the optimal terminal waypoints (fixes), whichaccounts for the derived priorities of each dynamic route, while meeting the required separation distances.The proposed Analytic Hierarchy Process model characteristics are validated by subject matter experts. Thedeveloped framework is applied to the London Metroplex case study.
Wilke S, Majumdar A, Ochieng WY, 2015, Modelling runway incursion severity, Accident Analysis & Prevention, Vol: 79, Pages: 88-99, ISSN: 0001-4575
Analysis of the causes underlying runway incursions is fundamental for the development of effective mitigation measures. However, there are significant weaknesses in the current methods to model these factors. This paper proposes a structured framework for modelling causal factors and their relationship to severity, which includes a description of the airport surface system architecture, establishment of terminological definitions, the determination and collection of appropriate data, the analysis of occurrences for severity and causes, and the execution of a statistical analysis framework. It is implemented in the context of U.S. airports, enabling the identification of a number of priority interventions, including the need for better investigation and causal factor capture, recommendations for airfield design, operating scenarios and technologies, and better training for human operators in the system. The framework is recommended for the analysis of runway incursions to support safety improvements and the methodology is transferable to other areas of aviation safety risk analysis.
Ali BS, Majumdar A, Ochieng WY, et al., 2015, A causal factors analysis of aircraft incidents due to radar limitations: The Norway case study, JOURNAL OF AIR TRANSPORT MANAGEMENT, Vol: 44-45, Pages: 103-109, ISSN: 0969-6997
Traditionally, the surveillance component of the air traffic management system has been based on radar, which consists of two separate systems: primary radar and secondary radar, which both enable the measurement of the aircraft range and bearing to the radar station. Primary radar is based on signals emitted by a ground station simply being reflected off an object and detected by a ground-based receiver. Secondary radar also emits signals, but relies upon a transponder onboard the aircraft to emit a signal itself, modulated among others by a four-digit aircraft identity (Mode A), aircraft altitude (Mode C) and/or 24-bit unique address (Mode S). Typical accuracies of secondary radar are of the order of 0.03 NM in range and 0.07° in azimuth. However, no position integrity report is provided. Air traffic density is expected to significantly increase in the future. In order to maintain or enhance air travel efficiency, while maintaining safety, more accurate surveillance systems, with the required integrity, will be required. Automatic dependent surveillance–broadcast (ADS-B) is a new aviation surveillance system, envisioned to overcome the limitations of radar and to enhance surveillance performance and thereby increase airspace capacity. However, its high dependence on external systems such as onboard navigation and communication systems also increases the number of potential points of failure. It is important to understand and mitigate these failure modes before the system can reliably be implemented. The present study emerged as an exploratory research as part of a safety assessment framework development for the ADS-B system. It reviews the ADS-B failure modes, data collection and analysis of ADS-B and its corresponding onboard GPS data. The study identifies a set of failures common to certain aircraft models, with consistent error patterns. A key failure mode was found to be associated with the navigation data from the onboard GPS. We discuss the identif
Kyriakidis M, Pak KT, Majumdar A, 2015, Railway Accidents Caused by Human Error: Historic Analysis of UK Railways, 1945 to 2012, TRANSPORTATION RESEARCH RECORD, Pages: 126-136, ISSN: 0361-1981
Sidiropoulos S, Majumdar A, 2015, A framework for the classification and prioritization of arrival and departure routes in Multi-Airport Systems Terminal Manoeuvring Areas
Typically major cities (London, New York, Tokyo) are served by several airports effectively creating a Multi-Airport System or Metroplex. The operations of the Metroplex airports are highly dependent on one another, which renders their efficient management difficult. The resulting inefficiencies have a negative impact on the airlines' operations. This paper proposes a framework for the prioritization of arrival and departure routes in Multi-Airport Systems Terminal Manoeuvring Areas with the aim of improving the overall system performance and its efficiency to accommodate the individual airspace users' needs. The framework consists of three components. The first component presents a new procedure for clustering arrival and departure flights into dynamic routes based on their temporal and spatial distributions through the identification of the important traffic flow patterns throughout the day of operations. The second component is a novel Analytic Hierarchy Process model for the prioritization of the dynamic routes, accounting for a set of quantitative and qualitative characteristics important for Multi-Airport Systems operations. The third component is a priority-based model for the facility location of the optimal terminal waypoints (fixes), which accounts for the derived priorities of each dynamic route, while meeting the required separation distances. The proposed Analytic Hierarchy Process model characteristics are validated by subject matter experts. The developed framework is applied to the London Metroplex case study.
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