Payuna Uday

Evaluation of potential near-term operational changes to mitigate environmental impacts of aviation

Changing aircraft operational procedures is one way of mitigating the environmental impacts of aviation in relatively short timeframes with existing aircraft types. However, to date these mitigations have not been evaluated or compared in a systematic manner that considers both their environmental impact reduction potential and their ability to be successfully implemented. This article presents a comprehensive identification and systematic evaluation of potential near-term operational changes to determine their relative environmental mitigation benefits. The research also evaluated the potential for successful implementation by identifying possible barriers to implementation for each mitigation. The analysis identifies the most promising mitigations offering a combination of environmental impact reduction and ease of implementation.

Designing Resilient Systems-of-Systems: A Survey of Metrics, Methods, and Challenges

Resilience is the ability of a system to react to and recover from disturbances with minimal effect on its dynamic stability. While resilience has been the focus of research in several fields, in the case of systems-of-systems SoSs, addressing resilience is particularly interesting and challenging. As infrastructure SoSs, such as power, transportation, and communication networks, grow in complexity and interconnectivity, measuring and improving the resilience of these critical SoSs is vital in terms of safety and providing uninterrupted services. While the resilience of SoSs depends on the reliability of their constituent systems, traditional reliability and risk assessment approaches cannot adequately quantify their resilience. In this paper, we provide an evaluation of the various methods available and challenges associated with designing resilient SoSs by 1 indicating important differences between resilience and various related system attributes, 2 providing a critical assessment of the current reliability and risk techniques in addressing SoS resilience, and 3 discussing the application of recent multidisciplinary research that can guide the design of resilient SoS. Finally, we highlight key challenges in this design process and propose a series of research themes that can shape future research in this field.

Exploiting Stand-in Redundancy to Improve Resilience in a System-of-Systems (SoS)

Abstract Resilience is the ability of a system or organization to react to and recover from disturbances with minimal effect on its dynamic stability. While the resilience of system-of systems (SoSs) depends on the reliability of their constituent systems, traditional reliability approaches cannot adequately quantify their resilience. Given the heterogeneity and often wide geographic distribution of SoS constituent systems, inclusion of backup redundant systems for a SoS is usually impractical and costly. In this paper, we quantitatively assess the impact of compensating for a loss of performance in one constituent system by re-tasking the remaining systems. We call this “stand-in redundancy”, and we develop two concepts to implement stand-in redundancy in a SoS. First, reactive resilience deals with performance recovery after a system failure has occurred. We provide a method to determine feasible alternative SoS configurations based on performance level recovery and cost of implementation. Second, proactive resilience takes into account the gradual degradation of systems over time. The corresponding reduction in SoS performance could initiate a forcible transition to a different SoS configuration before actual failure of the system. These concepts, and their resulting upstream effects on development costs and risks, can be used by decision-makers to quantitatively assess the impact on resilience of different SoS architectures and their inherent ability to resist failures throughout the SoS lifecycle.

Resilience-based System Importance Measures for System-of-Systems☆

Abstract Systems-of-systems (SoS) like the air transportation system and missile defense are gaining increasing attention in both the academic and practitioner communities. This research investigates one crucial aspect of SoSs: their ability to recover from disruptions, or their resilience. We develop a family of system importance measures (SIMs) that rank the constituent systems based on their impact on the overall SoS performance. The SIMs address some of the major weaknesses that have prevented researchers from identifying a single resilience metric. While trade-space analyses are standard practice in systems engineering, conducting trades on SoS resilience is difficult because, to date, no reliable and consistent metrics have been developed for SoS resilience. Some metrics have been proposed, but these measures assume homogenous networks, thus ignoring one of the key features of SoSs: the combination of heterogeneous systems (e.g., airports and aircraft) to achieve a common goal (e.g., transport). Instead of focusing on an overall metric, the set of SIMs provides designers with specific information on where an SoS is lacking resilience (or has excess resilience) and hence on where improvements are needed (or where downgrades are possible).

Evaluation of the Potential Environmental Benefits of RNAV/RNP Arrival Procedures

Improving aircraft operational procedures is one strategy that can be used to mitigate aviation’s environmental impacts in relatively short time-frames with existing aircraft types. This study quantifies the potential environmental benefits achievable with operational changes in Area Navigation (RNAV) and Required Navigation Performance (RNP) departure and approach procedures using a case study of approaches at SEATAC. Results indicate that properly designed RNAV/RNP procedures can yield fuel and emissions savings during approach of up to approximately 40 percent. However, the maximum benefits are only realized when procedures are optimized to improve environmental and operational performance. “Overlay” RNAV procedures, which are merely higher precision versions of existing non-RNAV procedures, often do not yield much fuel benefit or deliver any meaningful noise impact reduction.

An Analytic Workbench Perspective to Evolution of System of Systems Architectures

Abstract The development of a large group of interdependently operating systems, or ‘System of Systems (SoS)’, presents significant challenges across technical, operational and programmatic dimensions. Trades between cost, schedule, performance, and associated spectrum of risks, are essential during analysis of alternatives for both individual systems and the SoS architecture as a whole. The large number of decision variables involved, ubiquitous uncertainty and complex interactions that exist between systems creates analysis problems that go well beyond the immediate mental faculties of decision-makers. Often times, the decisions made focus on localized development at the systems level with little consideration for cascading effects on the bigger SoS picture. Hence, the process of evolving SoS architectures requires tools that provides the SoS practitioner with meaningful analytical quantifications of the SoS tradespace. In the defense arena, existing tools for such trades, have been guided by policies set forth in the Defense Acquisitions Guidebook (DAG) (5000 series) and the System Engineering Guide for System of Systems (SoS-SE), but are lacking an analytic perspective towards more informed decision-making. This paper discusses a multidisciplinary effort, funded by the DoDs Systems Engineering research Center (SERC), to establish an analytic workbench of computational tools to facilitate better-informed decision-making on SoS architectures. The work is motivated by the idea that SoS practitioners possess relevant information and archetypal questions that reflect desired outcomes at the SoS level. These archetypal, technically -driven queries are mapped to relevant methods that can provide analytical outputs to directly support SoS acquisition and architectural decisions. The applicability and respective value-added of each method in addressing various archetypal measures are presented.

Environmental Benefits of End-Around Taxiway Operations

*† ‡ Improving airfield design is one strategy that can be used to reduce aircraft emissions at airports. At high-traffic airports with parallel runways, end-around taxiways can reduce runway incursions as well as increase runway throughput. This study evaluates the environmental implications of these taxiways at a candidate airport, DFW (Dallas/FortWorth International Airport). The use of the end-around taxiway varies significantly on a daily basis. Since operations on the taxiway do not follow strict procedures, there is potential to develop procedures for the effective use of the end-around taxiway, in terms of taxi time and surface fuel burn reduction. While the end-around taxiway shows significant promise in terms of fuel burn and emissions reduction, these benefits depend on the manner of operation of the taxiway. Factors such as traffic conditions on adjacent runways, traffic flow direction, arrival time of aircraft, and the specific aircraft type play a major role in extracting environmental benefits from end-around taxiways. For example, the results show that the average fuel burn for aircraft using the end-around taxiway is less than the average fuel burn of aircraft using a conventional taxiway during a select portion of the day, specifically, between 5pm and 1am. Further, implementation of decision rules based on the results of this research show promise in terms of fuel burn reduction.