Nonstop Flying Is Safer Than Driving

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73935/1/j.1539-6924.1991.tb00584.x.pd

A Risk Assessment Architecture for Enhanced Engine Operation

On very rare occasions, in-flight emergencies have occurred that required the pilot to utilize the aircraft's capabilities to the fullest extent possible, sometimes using actuators in ways for which they were not intended. For instance, when flight control has been lost due to damage to the hydraulic systems, pilots have had to use engine thrust to maneuver the plane to the ground and in for a landing. To assist the pilot in these situations, research is being performed to enhance the engine operation by making it more responsive or able to generate more thrust. Enabled by modification of the propulsion control, enhanced engine operation can increase the probability of a safe landing during an inflight emergency. However, enhanced engine operation introduces risk as the nominal control limits, such as those on shaft speed, temperature, and acceleration, are exceeded. Therefore, an on-line tool for quantifying this risk must be developed to ensure that the use of an enhanced control mode does not actually increase the overall danger to the aircraft. This paper describes an architecture for the implementation of this tool. It describes the type of data and algorithms required and the information flow, and how the risk based on engine component lifing and operability for enhanced operation is determined

Current Methods for Modeling and Simulating Icing Effects on Aircraft Performance, Stability and Control

Icing alters the shape and surface characteristics of aircraft components, which results in altered aerodynamic forces and moments caused by air flow over those iced components. The typical effects of icing are increased drag, reduced stall angle of attack, and reduced maximum lift. In addition to the performance changes, icing can also affect control surface effectiveness, hinge moments, and damping. These effects result in altered aircraft stability and control and flying qualities. Over the past 80 years, methods have been developed to understand how icing affects performance, stability and control. Emphasis has been on wind tunnel testing of two-dimensional subscale airfoils with various ice shapes to understand their effect on the flow field and ultimately the aerodynamics. This research has led to wind tunnel testing of subscale complete aircraft models to identify the integrated effects of icing on the aircraft system in terms of performance, stability, and control. Data sets of this nature enable pilot in the loop simulations to be performed for pilot training, or engineering evaluation of system failure impacts or control system design

Investigation of the Impacts of Effective Fuel Cost Increase on the US Air Transportation Network and Fleet

The cost of aviation fuel increased 244% between July 2004 and July 2008, becoming the largest operating cost item for airlines. Given the potential for future increases in crude oil prices, as well as environmental costs (i.e. from cap and trade schemes or taxes), the effective cost of aviation fuel may continue to increase, further impacting airlines’ financial performance and the provision of air service nationwide. We evaluate how fuel price increase and volatility affected continental US air transportation networks and fleets in the short- and medium-term using the increase in the 2007-08 and 2004-08 periods as a natural experiment. It was found that non-hub airports serving small communities lost 12% of connections, compared to an average loss of 2.8%, July 2004-08. It is believed that reduced access to the national air transportation system had social and economic impacts for small communities. Complementary analyses of aircraft fuel efficiency, airline economics, and airfares provided a basis for understanding some airline decisions. Increased effective fuel costs will provide incentives for airlines to improve fleet fuel efficiency, reducing the environmental effects of aviation, but may cause an uneven distribution of social and economic impacts as airline networks adapt. Government action may be required to determine acceptable levels of access to service as the air transportation system transitions to higher fuel costs.The authors would like to thank the MIT Partnership on AiR Transportation Noise & Emissions Reduction (PARTNER) for access to the Piano-X software package and Brian Yutko for his assistance in its use. This work was supported by the MIT/Masdar Institute of Science and Technology under grant number Mubadala Development Co. Agreement 12/1/06

Towards High-resolution Imaging from Underwater Vehicles

Large area mapping at high resolution underwater continues to be constrained by sensor-level environmental constraints and the mismatch between available navigation and sensor accuracy. In this paper, advances are presented that exploit aspects of the sensing modality, and consistency and redundancy within local sensor measurements to build high-resolution optical and acoustic maps that are a consistent representation of the environment. This work is presented in the context of real-world data acquired using autonomous underwater vehicles (AUVs) and remotely operated vehicles (ROVs) working in diverse applications including shallow water coral reef surveys with the Seabed AUV, a forensic survey of the RMS Titanic in the North Atlantic at a depth of 4100 m using the Hercules ROV, and a survey of the TAG hydrothermal vent area in the mid-Atlantic at a depth of 3600 m using the Jason II ROV. Specifically, the focus is on the related problems of structure from motion from underwater optical imagery assuming pose instrumented calibrated cameras. General wide baseline solutions are presented for these problems based on the extension of techniques from the simultaneous localization and mapping (SLAM), photogrammetric and the computer vision communities. It is also examined how such techniques can be extended for the very different sensing modality and scale associated with multi-beam bathymetric mapping. For both the optical and acoustic mapping cases it is also shown how the consistency in mapping can be used not only for better global mapping, but also to refine navigation estimates.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/86051/1/hsingh-21.pd

Voices unheard : employee voice in the new century

The concept of employee voice has attracted considerable attention in research since the 1980s primarily in the fields of Employment Relations/Human Resource Management (ER/HRM) and Organisational Behaviour (OB). Each of these disciplines focuses on different aspects of employee voice, the former examining the mechanisms for employees to have \u27a say\u27 in organisational decision-making (Freeman, Boxall, & Haynes, 2007; Gollan, Kaufman, Taras, & Wilkinson, 2015; Wilkinson & Fay, 2011) and the latter considering voice as an \u27extra-role upward communication behaviour\u27 (Morrison, 2014, p. 174) with the intent to improve organizational functioning. The purpose of voice is seen by each of these disciplines in a different way. ER/HRM perspectives are underpinned by the assumption that it is a fundamental democratic right for workers to extend a degree of control over managerial decision-making within an organisation (Kaufman, 2015; Wilkinson, Gollan, Lewin, & Marchington, 2010). Thus, everyone should have a voice and a lack of opportunities to express that voice may adversely affect workers\u27 dignity. In contrast, OB perspectives are underpinned more by a concern with organisational improvements, therefore leaving it much more to managerial discretion to reduce or change existing voice arrangements due to, for example, an economic downturn (Barry & Wilkinson, 2016)