Development of an automated aircraft subsystem architecture generation and analysis tool

Purpose – The purpose of this paper is to present a new computational framework to address future preliminary design needs for aircraft subsystems. The ability to investigate multiple candidate technologies forming subsystem architectures is enabled with the provision of automated architecture generation, analysis and optimization. Main focus lies with a demonstration of the frameworks workings, as well as the optimizers performance with a typical form of application problem. Design/methodology/approach – The core aspects involve a functional decomposition, coupled with a synergistic mission performance analysis on the aircraft, architecture and component levels. This may be followed by a complete enumeration of architectures, combined with a user defined technology filtering and concept ranking procedure. In addition, a hybrid heuristic optimizer, based on ant systems optimization and a genetic algorithm, is employed to produce optimal architectures in both component composition and design parameters. The optimizer is tested on a generic architecture design problem combined with modified Griewank and parabolic functions for the continuous space. Findings – Insights from the generalized application problem show consistent rediscovery of the optimal architectures with the optimizer, as compared to a full problem enumeration. In addition multi-objective optimization reveals a Pareto front with differences in component composition as well as continuous parameters. Research limitations/implications – This paper demonstrates the frameworks application on a generalized test problem only. Further publication will consider real engineering design problems. Originality/value – The paper addresses the need for future conceptual design methods of complex systems to consider a mixed concept space of both discrete and continuous nature via automated methods

Environmental Impact Assessment, on the Operation of Conventional and More Electric Large Commercial Aircraft

Global aviation is growing exponentially and there is a great emphasis on trajectory optimization to reduce the overall environmental impact caused by aircraft. Many optimization techniques exist and are being studied for this purpose. The CLEAN SKY Joint Technology Initiative for aeronautics and Air transport, a European research activity run under the Seventh Framework program, is a collaborative initiative involving industry, research organizations and academia to introduce novel technologies to improve the environmental impact of aviation. As part of the overall research activities, "green" aircraft trajectories are addressed in the Systems for Green Operations (SGO) Integrated Technology Demonstrator. This paper studies the impact of large commercial aircraft trajectories optimized for different objectives applied to the on board systems. It establishes integrated systems models for both conventional and more electric secondary power systems and studies the impact of fuel, noise, time and emissions optimized trajectories on each configuration. It shows the significant change in the fuel burn due to systems operation and builds up the case as to why a detailed aircraft systems model is required within the optimization loop. Typically, the objective in trajectory optimization is to improve the mission performance of an aircraft or reduce the environmental impact. Hence parameters such as time, fuel burn, emissions and noise are key optimization objectives. In most instances, trajectory optimization is achieved by using models that represent such parameters. For example aircraft dynamics models to describe the flight performance, engine models to calculate the fuel burn, emissions and noise impact, etc. Such techniques have proved to achieve the necessary level of accuracy in trajectory optimization. This research enhances previous techniques by adding in the effect of systems power in the optimization process. A comparison is also made between conventional power systems and more electric architectures. In the conventional architecture, the environmental control system and the ice protection system are powered by engine bleed air while actuators and electrics are powered by engine shaft power off-takes. In the more electric architecture, bleed off take is eliminated and the environmental control system and ice protection system are also powered electrically through engine shaft power off takes

Formation flight investigation for highly efficient future civil transport aircraft

Formation flight could greatly assist the air transport industry in tackling the challenges of environmental impact, excessive reliance on fuel and overcapacity. Previous studies have shown drag reductions leading to significant fuel savings for aircraft in formation relative to their solo flight. Safety is guaranteed with the use of extended formation distances, and practical implementation issues could be solved in the near future. Since studies so far have focused on existing aircraft configurations and technology, a case study using a strut-braced wing airliner was carried out to ascertain its applicability to less conventional craft. The present results did not indicate such clear-cut benefits. If formation flight is to be successful and beneficial for the next generations of aircraft, it will be vital to consider its interaction with new technologies developed for highly efficient operation, in particular those aimed at reduction of aircraft drag such as laminar flow, and to do so early in the design of aerospace vehicles and wider systems

Introduction: Medical Science, Moral Controversy, and Legal Change

This symposium issue of the Nebraska Law Review is focused explicitly on aspects of physician authority and patient autonomy. The progress of AIDS has everywhere thrown up a myriad of difficult legal issues. These range from issues of research confidentiality to civil liability for transfusion-associated AIDS; from the rights and duties of staff health care professionals who wish to avoid contact with AIDS patients being treated at the institutions where they work, to the rights and duties of health care professionals who wish to treat AIDS patients over the objections of landlords, professional associates, and others. The courts have once more become the primary forum for the resolution of a set of perplexing medicolegal issues. All of the symposium articles importantly involve legal change, not only in centering on the concept of patient autonomy but also in arguing for further legal change, or in arguing for correspondingly changed medical practices in the spirit of the developing law of patient autonomy

Symbiosis and Bioinvasive Dynamics of Durusdinium trenchii and its Acroporid Coral Hosts

Biological invasions are a growing threat to coral reef ecosystems, as increasing anthropogenic transport and changing environmental patterns allow invasive species to establish and spread. Durusdinium trenchii is a dinoflagellate that has invaded the Greater Caribbean reef system and established symbioses with coral hosts. Establishment and persistence of invasive endosymbionts like D. trenchii could indicate a shift in the clade composition of coral holobionts worldwide. Statistical analyses were performed on the GeoSymbio database (Franklin et al. 2012) to determine whether differences in clade composition have occurred over time. Factors that influence biological invasions in marine ecosystems were assessed and analogous fields of study compared with invasion ecology. As no management frameworks currently exist that govern invasive marine microbes like D. trenchii, a management framework designed to account for these component fields of study is proposed[DER1] . Prominent and successful cases of marine bioinvasion management were reviewed and their potential applications assessed. These case studies were synthesized with modern control methods to create a framework for bioinvasion management that is specific to D. trenchii. The framework focuses on detection and preventative control of invasive transport vectors. [DER2] [DER1]Add a few sentences here to describe the framework. [DER2]There is still room here for a brief description of your frame work recommendations

Development of a tool to study aircraft trajectory optimisation in the presence of icing conditions

With the increasing demand of air travel, the impact on the environment due to aviation has shown a significant increase in recent times. As a result, there is a growing demand for new technologies and flight procedures that will enable aircraft operators to burn less fuel and reduce the adverse effect of aviation on the environment. Conventional approaches to trajectory optimisation do not take the effect of aircraft systems into account. Neglecting these effects may be inadequate, especially when one considers real aircraft operations in real weather scenarios. This research has developed a tool capable of simulating aircraft ice protection performance for trajectory optimisation, which enables the development of a decision making process dependent on weather within the flight management system, thus transforming the conventional ice protection system to a more intelligent system. Presently, thermal ice protection methods are the leading ice protection technology on most of the medium and large transport aircraft. An enhanced aircraft anti-icing model was developed based on Messinger mass and energy balance method for thermal anti-icing. The tool developed in this work can calculate the total water catch and evaluate power requirement due to icing under a wide range of meteorological conditions. The model was successfully integrated with a trajectory optimisation framework for independent assessment of fuel penalty due to icing and investigation of pollutant emissions reduction through aircraft trajectory optimisation. A case of typical departure from London Airport Heathrow was optimised for fuel burn and time. The preliminary results show that when operating in known icing condition, including icing parameters in the optimisation loop could give as much as 2.1% fuel savings

Electrical load-sizing methodology to aid conceptual and preliminary design of large commercial aircraft

The importance of the more electric aircraft has been highlighted in many publications, projects and industrial presentations. By definition, the more electric aircraft concept achieves the majority of the required system functionality by using electrically powered sub-systems and components. This manifests itself in much higher electrical power demands on-board aircraft, compared to conventional architectures. This presents many challenges in the design process. To alleviate the risk and choose the optimum architectures for the systems on the aircraft, it is essential to incorporate the characteristics and possible configurations of the electrical network in the conceptual and preliminary design stages. Hence the current practice of performing an electrical load analysis at the detailed design stage is not adequate. To address this gap, this paper presents a viable and robust methodology to define requirements, size components and systems and calculates the electric power requirements at the preliminary design stages. The methodology uses the conventional aircraft, systems and components as the baseline and uses mathematical techniques and logical sequences of component operation, developed through the research, to size electrical load profiles for conventional aircraft. It then adapts this result to the more electric aircraft concept by adding key components that would account for the difference between a conventional system and a more electric system. The methodology presented here makes the design process more robust and aids the choice of the optimum design for the aircraft

Design manufacturing integration and flight testing of a health monitoring system for a prototype unmanned airborne vehicle

This article describes the design, development, build and flight testing of a health monitoring system for the landing gear and the electrical power system on board the Demon prototype unmanned airborne vehicle. Demon is a flying technology demonstrator which successfully flew in September 2010. The Demon can achieve pitch and roll control without the use of hinged control surfaces, by instead using fluidic devices based on the Coanda effect, attaining low-maintenance, high-manoeuvrability operations. A vehicle health monitoring system was added on board between the first and the second flight test campaigns. The integration of the health monitoring system into the vehicle is discussed as a whole. The key health monitoring sub-systems include data logging and real-time measurement of several parameters. This includes systems to measure Voltage and current from the main batteries, landing gear stress, suspension travel, wheel hub acceleration and shock absorber pressure. Wherever possible, the use of commercially available components was maximised to minimise development time and cost. Some example results of system health monitoring during flight trials are presente

Experimental investigation into aircraft system manual assembly performance under varying structural component orientations

Installation of aircraft wing systems is a bottleneck in the assembly process. This phase is typically composed of many work packages, taking hundreds of man-hours per wing. In addition to this volume of work, tasks are specialized and completed in a difficult environment in terms of access and visibility. In current industrial practice, the wing is mounted horizontally on a transport trolley, which exposes the workforce to prolonged periods of overhead working. Future wing designs may consider a pre-equipping build philosophy, where systems are installed to major structure assemblies before the wing box is assembled. This allows for a change in the orientation and position of the major structure and provides new freedoms in assembly station design and layout. This research presents results of experiments to investigate manual assembly performance of aircraft wing systems, under varying wing structure orientation. A mock-up of a section of an A320 aircraft wing front spar, mounted on a rotation device, functions as the testbed. Manual installation activities are then conducted to emulate real aircraft system equipping for electric harnesses, raceways and hot air ducts. The results show a best-case assembly performance change of 36% for electric system installation activities of cable harnesses and raceway housing components. Tilted and horizontal orientations of the structure show the highest time reductions, with the vertical orientation either non-conclusive or increasing the assembly time. The outcomes of this study are intended to aid in effective trade-off decision making for future wing systems and assembly station layouts from the perspective of structural orientation and assembly task interaction