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Viewing 181 to 210 of 22052
2015-09-15
Technical Paper
2015-01-2541
Alejandro Murrieta-Mendoza, Ruxandra Botez
Abstract This paper describes an optimization algorithm that provides an economical Vertical Navigation profile plan by finding the combinations of climb, cruise and descent speeds, as well as the altitudes for an aircraft to minimize flight costs. The computational algorithm profits from a space search reduction algorithm to reduce the initial number of speed and altitude combinations. Additional search space reductions were performed with the implementation of the branch and cut algorithm. A bounding function that correctly estimates the flight cost considering step climbs was developed to reduce the number of calculations. The full flight fuel burn cost was obtained using a performance database- based method. The fuel flight cost was computed using the cost index. This algorithm used a performance database instead of equations of motion to compute fuel burn. This database was developed and validated by our industrial partner using real flight experimental data.
2015-09-15
Technical Paper
2015-01-2549
Marc-André Léonard, Jean-François Boland, Christophe Jégo, Claude Thibeault
Abstract Design assurance guidance such as DO-254, and commercial off the shelf (COTS) increasing popularity in high critical mission have pushed the validation and verification methodologies to improve by integrating fault tolerance analysis in reliability assessment. A novel methodology for analysing the sensitivity of digital designs to single event upsets (SEU) is proposed. We first characterize basic combinational circuit models using fault injection via mutation technique at low level of abstraction. Error analysis is performed at primary outputs to identify patterns that are collected in a faulty behaviour library. This library is then used at a high level of abstraction to execute a sensitivity analysis on a digital design model. A reliability report is then generated showing the soft error rate (SER) and the benign errors count. We proved our methodology by analysing the radiation sensitivity of a discrete wavelet transform architecture using two different sets of data.
2015-09-15
Technical Paper
2015-01-2554
Kevin Landry, Jean-François Boland, Guy Bois
Abstract The amount of functionalities in modern aircrafts is increasing to satisfy performance, safety and economic benefits. Therefore, the communication needs of avionic systems are growing. Furthermore, the portability and reusability of applications are current challenges of the aerospace industry. The use of the Data Distribution Service (DDS) middleware technology would reduce the complexity of communications and ease the portability and reusability of applications with its standardised interface. Few previous works used a DDS middleware within the aerospace industry and those didn't take into account the impact of this technology on the applications performances. Therefore, this paper presents an impact evaluation of using a DDS middleware on the performances of avionic applications.
2015-09-15
Technical Paper
2015-01-2395
Vikhyat Chaudhry, Ishan Mishra
This paper describes the ZENITH Nano-Satellite cum planetary atmospheric entry vehicle, called CanSat, the first Nano-Satellite project that has been developed by Delhi Technological University (Formerly Delhi College of Engineering), India. The satellite will function for monitoring the concentrations of various gases in the atmosphere. For this, the satellite consists of arduino microcontroller interfaced with the various Micro-electromechanical system (MEMS) gas sensors for measuring the concentrations of various gases such as carbon dioxide, carbon monoxide, methane, nitrous oxides, ozone, etc. The data obtained from the CanSat will be transmitted to the ground station where all the data will be stored and also the locations will be stored using GPS sensor. The academic goal of this project is to recruit students to the field of space science and technology.
2015-09-15
Technical Paper
2015-01-2407
Theodoros Kostakis, Patrick Norman, Steven Fletcher, Stuart Galloway, Graeme Burt
The aviation industry has witnessed a technological shift towards the More-Electric Aircraft (MEA) concept. This shift has been driven by a number of perceived benefits including performance optimization and reduced life-cycle costs. Increased electrification within MEA has made aircraft electrical networks larger and more complex and this necessitates an increased electrical power offtake from the engine. With this comes the need to better optimise the efficiency of engine electrical power extraction. The paralleling of multiple generation sources across the aircraft is one potential design approach which could help improve engine operability and fuel efficiency within more-electric aircraft platforms and this paper will investigate options for this to be implemented within the context of current design and certification rules.
2015-09-15
Technical Paper
2015-01-2410
Fei Gao, Serhiy Bozhko, Greg Asher, Patrick Wheeler
DC electrical power system (EPS) for the future more electric aircraft (MEA) is promising due to several advantages such as lower system cost and simpler structure. So far, dominant control methods for proper power sharing can be mainly divided into two categories: active load sharing and passive load sharing. For active load sharing scheme, three common approaches are popular: master-slave control (MS), centralized control and average current control. The common of three approaches is the need of communication line among the parallel modules. On the other hand, most of the recent research is focused on passive load sharing (decentralized control method) e.g., droop control. As a decentralized control method, parallel modules can operate independently since no communication among the sources is needed.
2015-09-15
Technical Paper
2015-01-2409
Constanza Ahumada S., Seamus Garvey, Tao Yang, Patrick Wheeler, Herve Morvan
This paper considers the electromechanical interconnection between the electrical power system of the More Electric Aircraft (MEA) and the shaft connecting the engine to the generator. In order to probe the existing coupling between these two systems and therefore the necessity of studying them together, the effect of an electric load impact on the mechanical system of the MEA will be analyzed. As the MEA concept, replaces the pneumatic, hydraulic and mechanical systems by electrical systems, the electrical power rating of the MEA is considerable higher than the power rating of existing aircraft and consequently new challenges arise. A larger electrical power system implies larger generators and higher power loads, which can have higher associated electrical transients. Moreover, unlike in previous aircraft and most ground based electrical power systems, in the MEA the short term changes in power tend not to be small compared to the total load in the system.
2015-09-15
Technical Paper
2015-01-2413
Anngwo Wang, Jonathan Davies, Seth Gitnes, Lotfi El-Bayoumy
The instantaneous efficiency of an epicyclic geared rotary actuator is an important factor in sizing flight control systems where compound epicyclic gear trains are typically used. The efficiency variation can be smooth or fluctuating depending on the combination and timing of the teeth of ring gears, planet gears and sun gears. In a previous paper [1], the instantaneous efficiency characteristics of actuators with symmetric planets were investigated. The actuator’s reacting forces on the planets are symmetric and the overall length of the planet gears will not affect the efficiency. In this paper, a cantilever actuator with asymmetric planet gears is studied. The length and location of the reaction forces on the planet gears are key factors in the efficiency calculation.
2015-09-15
Technical Paper
2015-01-2411
Michal Sztykiel, Steven Fletcher, Patrick Norman, Stuart Galloway, Graeme Burt
The increasing electrical demand in commercial and military aircraft justifies a growing need for higher voltage DC (e.g. ±270 VDC) primary distribution systems. A ±270VDC system offers reduced power losses and space savings, which is of major importance for aircraft manufacturers. At present, challenges associated with ±270 VDC systems include reliable fast acting short circuit protection. Solid State Contactors (SSC) have gained wide acceptance in traditional 28 VDC secondary systems for DC fault interruption. Nevertheless, the generation of adequate arc voltages for interruption at higher operating voltages and currents requires further technology maturation. This paper demonstrates an alternative method for fault mitigation by introducing bidirectional AC/DC converter topology with DC fault current blocking capability. Presently utilized converters lack this blocking feature due to the existing path for the fault current flow through the anti-parallel diodes.
2015-09-15
Technical Paper
2015-01-2415
Kyle Shimmin, Greg Russell, Robert A. Reuter, Steven Iden
A reduced order dynamic aircraft model has been created for the purpose of enabling constructive simulation studies involving integrated electrical power and thermal management subsystems using Multidisciplinary Design Optimization methods. Previous higher-order models that have been used for this purpose have the drawbacks of much higher development time, along with much higher execution times in the simulation studies. The new formulation allows for climbs, accelerations and turns without incurring computationally expensive stability considerations; a dynamic inversion control law provides tracking of user-specified mission data. To assess the trade-off of improved run-time performance against model capability, the reduced order formulation is compared to a traditional six degree-of-freedom model of the same air vehicle. Thrust command comparisons against the higher fidelity model are shown to be excellent.
2015-09-15
Technical Paper
2015-01-2414
Carsten Dunker, Riko Bornholdt, Frank Thielecke, Robert Behr
The More-Electric Aircraft is considered to be one of the main goals for future aircraft systems. An important milestone of this aim, the All-Electric Engine without hydraulic pumps and bleed-air systems, could be realized by using electro-hydraulic power generation and central hydraulic distribution systems. These systems are powered by electric motor pumps and use cost-efficient and state of the art hydraulic actuator technologies. Additionally, this approach would comply with the present incremental development strategy of the airplane manufacturers. Although changes seem to be small these architectures have a major effect on the hydraulic system sizing. Therefore a methodology for an initial architecture optimization of hydraulic power systems and a subsequent parameter optimization is presented to evaluate the design space for future electro-hydraulic architectures.
2015-09-15
Technical Paper
2015-01-2420
Henry A. Catherino
The heat generation rate of a lithium ion cell was estimated using a reversible heat generation rate equation. Because the equation is based on the energy conservation law, the influence of kinetically slow processes should be considered. In this analysis, the influence of kinetically slow processes is present but it is small within the domain of the test measurements. This approximation can be of significant usefulness for modeling the thermal response of single cells and multi-cell batteries.
2015-09-15
Technical Paper
2015-01-2434
Tian Lirong, Mu Ming
Abstract: Chinese aviation industry is now making great efforts in developing civil aircraft, as a result, more opportunities for Chinese companies to be involved in these programs, but Chinese companies are lack of experience in this area, certification is one of the challenges for them,so they are expected to be more competitive in design and certification. ACTRI (Aeronautical Computing Technique Research Institute) is a airborne computer supplier in China, to be able to develop electronic equipment for civil aircraft, the company has being working on processes improvement including the system process based on ARP4754 since 2008. This paper describes the customized system process in Chinese context.
2015-09-15
Technical Paper
2015-01-2438
Robert E. Voros
Aerospace Recommended Practice 4754 Revision A (ARP4754A), “Guidelines for Development of Civil Aircraft and Systems,” and ARP4761, “Guidelines and Methods for Conducting the Safety Assessment Process on Civil Airborne Systems and Equipment,” together describe a complex set of intertwining processes which comprehensively prioritize development activities for a product’s systems based on their safety criticality. These processes work at specific levels of detail (aircraft and system) and interact with a set of processes at lower levels of detail (item) defined by Radio Technical Commission for Aeronautics (RTCA) standards. The aircraft and system development process (ARP4754A) supplies functions, requirements, and architectural definitions to the system safety process (ARP4761), which in turn supplies Development Assurance Levels back to the development process and on to the RTCA processes.
2015-09-15
Technical Paper
2015-01-2439
Martin Hunter
It is generally accepted that the development of hardware and software for safety critical systems follow their own lifecycles as defined by standards such as RTCA DO254 and RTCA DO178C. What is less clear, is what should be done to ensure the system safety objectives are met when the software is installed in the electronic hardware. This paper seeks to discuss the activities that may be undertaken do demonstrate not only that the integration of the software and hardware "work" together, but they do so in a manner that meets the safety objectives in line with the guidance in SAE ARP4754A. According to ARP 4754A, hardware and software are different “items” developed according to their own requirements and standards, when two or more items are brought together, they are a system, which may be part of a larger system. Therefore system level considerations need to be applied from the beginning of the development program addressing the system safety and certification activities.
2015-09-15
Technical Paper
2015-01-2443
Nivedita Chanda
Aircrafts use Transponder for transmitting data to Air Traffic Control. Transponders automatically transmit a unique four-digit code when they receive a radio signal sent by radar. Code gives the plane's identity and radar stations establish speed and direction by monitoring successive transmissions. This data is then relayed to air traffic controllers. However, the aircraft mishaps have risen alarmingly in the past few decades resulting in unpredictable losses of human lives, nature, economically along with commotion of systems. This has necessitated active research work to fundamentally design better and effective systems. At present, there is no evident redundant system to transponder unlike in case of Power-Plants, three-fold reliable, safety cum redundant power supply system are present.
2015-09-15
Technical Paper
2015-01-2584
Andrew Dickerson, Ravi Rajamani, Mike Boost, John Jackson
Based on a advanced modeling approach, we are developing a system for estimating the remaining useful life (RUL) for Li-Ion batteries for aerospace applications. We begin with a set of functional requirements that are further translated to detailed system and maintenance specifications. We will show how this RUL calculator will be translated to actual algorithms and operating procedures inside a battery’s management unit. Test data will be used to validate the robustness and goodness in the predictions. We will also share plans for the future along with implications for certification of the system. This is important because batteries are governed by FAA regulations and are dispatch critical for certain applications.
2015-09-15
Technical Paper
2015-01-2583
James Hare, Shalabh Gupta, Nayeff Najjar, Paul D'Orlando, Rhonda Walthall
This paper addresses the issue of detecting and isolating faults in complex networked systems. Complex Networked Systems typically contain multiple subsystems, components, and sensors interconnected through feedback control and thermal couplings. When a fault occurs in a component of a complex networked system, the effects of the fault may cause offnominal operations in other components due to fluctuations in their input signals. Health monitoring algorithms developed in literature typically result in false alarms during these scenarios since the data observed through sensor measurements are showing unhealthy characteristics even though the components are performing correctly given their offnominal input signals. This paper proposes a System Level Isolation and DEtection (SLIDE) algorithm that will detect and isolate faults occurring in multiple subsystems while reducing the computational complexity and minimizing false alarms.
2015-09-15
Technical Paper
2015-01-2587
Matthew Smith, Peter F. Sulcs, Rhonda Walthall, Mark Mosher, Gregory Kacprzynski
Aircraft System Health Management (ASHM) is a UTC developed web application that provides access to Aircraft Condition Monitoring Function (ACMF) reports and Flight Deck Effects (FDE) records for B787 and A320 a/c. The tool was built with a flexible architecture to field a range of off-board diagnostics and prognostics modules designed to transform an abundance of data into actionable and timely knowledge about fleet health. This paper describes the ASHM system architecture and implementation with a focus on “lessons learned” in applying diagnostic and prognostics algorithms to available fleet data. Key topics include managing data quality issues, design for cross-enterprise collaboration and defining a workable approach to testing, validating and deploying prognostics and diagnostics models with various degrees of complexity. A case study is provided related to fluid leak detection within an environmental control subsystem.
2015-09-15
Technical Paper
2015-01-2403
Jennifer C. Shaw, Steven Fletcher, Patrick Norman, Stuart Galloway, Graeme Burt
Abstract A number of concepts have been proposed to meet future aircraft performance goals. One such concept under consideration is Turboelectric Distributed Propulsion (TeDP) featuring a large number of superconducting motors powered by two superconducting generators placed on each wingtip and connected through a DC distribution network. A key aspect in any design concept is the ability to prove that the system will exhibit a satisfactory reliability for all intended operating conditions. A common tool to support the calculation of failure rates and reliability is Fault Tree Analysis (FTA), and this will be utilized within this paper. The paper undertakes an architectural level FTA on a NASA proposed TeDP architecture to identify any significant factors contributing to the failure rate of key functionalities within the network.
2015-09-15
Technical Paper
2015-01-2551
Ephraim Suhir, Alain Bensoussan
In some today’s and future optoelectronic packaging systems, including those intended for aerospace applications, the package (system’s component containing active and/or passive devices and interconnects) is placed (“sandwiched”) between two substrates, which, in an approximate analysis, could be considered identical. Such a system is bow-free. This might be an important merit that could be helpful in maintaining high coupling efficiency in warpage-sensitive optical devices. The highest thermal stresses in such a tri-component (one inner and two outer components) bi-material (the composite material of the inner component - package and of the material of the outer components - substrates) assembly occur at low temperature conditions, are caused by the thermal contraction mismatch of the dissimilar materials of the assembly components and include normal stresses acting in the cross-sections of the components, and interfacial shearing and peeling stresses.
2015-09-15
Technical Paper
2015-01-2556
Thomas Rousselin, Guillaume Hubert, Didier Regis, Marc Gatti
The changes brought by the increasing integration density and the new technological trends have pushed the reliability at its limit. Safety analysis for critical system such as embedded electronics for avionics systems needs to take into account these changes. In this paper, we present the consequences on the Deep Sub-Micron (DSM) CMOS devices concerning their single event effect (SEE) sensitivity. We also propose a new modeling method in order to address these issues.
2015-09-15
Technical Paper
2015-01-2529
Mahendra Muli, Vivek Moudgal, Jace Allen
Abstract The Aerospace and Defense industry is currently challenged in multiple ways - cost cutting and sequestration on the defense side, and spurt of growth on the commercial aviation side of business. While these are opposing trends, both will impose severe challenges to the management of product development process for both the Air framers and the suppliers. The challenge becomes severe as the innovation expectations become rapid with increases in embedded software content in avionics and the advent of a new category of autonomous ground, marine, and air systems. Clearly, the industry need is to have a product development process that allows for reducing costs, while increasing embedded software quality and thereby product quality even in an iterative development process.
2015-09-15
Technical Paper
2015-01-2453
Danilo Andreoli, Mario Cassaro, Manuela Battipede, Goodarz Ahmadi, Piergiovanni Marzocca
Abstract Flow control over aerodynamic shapes in order to achieve performance enhancements has been a lively research area for last two decades. Synthetic Jet Actuators (SJAs) are devices able to interact actively with the flow around their hosting structure by providing ejection and suction of fluid from the enclosed cavity containing a piezo-electric oscillating membrane through dedicated orifices. The research presented in this paper concerns the implementation of zero-net-mass-flux SJAs airflow control system on a NACA0015, low aspect ratio wing section prototype. Two arrays with each 10 custom-made SJAs, installed at 10% and 65% of the chord length, make up the actuation system. The sensing system consists of eleven acoustic pressure transducers distributed in the wing upper surface and on the flap, an accelerometer placed in proximity of the wing c.g. and a six-axis force balance for integral load measurement.
2015-09-15
Technical Paper
2015-01-2458
Giuseppe Sirigu, Manuela Battipede, Piero Gili, Mario Cassaro
Abstract The future revolution of the air traffic system imposes the development of a new class of Flight Management Systems (FMS), capable of providing the aircraft with real-time reference flight parameters, necessary to fly the aircraft through a predefined sequence of waypoints, while minimizing fuel consumption, noise and pollution emissions. The main goal is to guarantee safety operations while reducing the aircraft environmental impact, according to the main international research programs. This policy is expected to affect also the Unmanned Aerial Systems (UASs), as soon as they will be allowed to fly beyond the restricted portions of the aerospace where they are currently confined. In the future, in fact, UASs are expected to fly within the whole civilian airspace, under the same requirements deriving from the adoption of the Performance Based Navigation (PBN).
2015-09-15
Technical Paper
2015-01-2459
Francesco Cappello, Subramanian Ramasamy, Roberto Sabatini
Abstract Multi-Sensor Data Fusion (MSDF) techniques involving satellite and inertial-based sensors are widely adopted to improve the navigation solution of a number of mission- and safety-critical tasks. Such integrated Navigation and Guidance Systems (NGS) currently do not meet the required level of performance in all flight phases of small Remotely Piloted Aircraft Systems (RPAS). In this paper an innovative Square Root-Unscented Kalman Filter (SR-UKF) based NGS is presented and compared with a conventional UKF governed design. The presented system architectures adopt state-of-the-art information fusion approach based on a number of low-cost sensors including; Global Navigation Satellite Systems (GNSS), Micro-Electro-Mechanical System (MEMS) based Inertial Measurement Unit (IMU) and Vision Based Navigation (VBN) sensors.
2015-09-15
Technical Paper
2015-01-2525
Dave Duncan
Abstract The verification of Robustness is conceptually simple, once the reasonable set of “abnormal operating conditions” has been established. During testing those conditions are created and the FPGA/CEH response is noted. Depending upon system requirements, sometimes the FPGA/CEH response need not be “to work normally” but should at a minimum return to normal operation once normal conditions are reestablished. Part of the analysis is to establish acceptable FPGA/CEH responses to the “abnormal operating conditions”. Some of the acceptable responses may actually affect the LRU/CCA hardware performance or software functions hosted on the system, an early identification of such interdependence is essential for the planning of robustness testing. The test cases implementing robustness testing conform to the same constraints and pedigree as any requirements based test case. The key here is to know the scope of the tests and plan accordingly.
2015-09-15
Technical Paper
2015-01-2558
Jörg Brauer, Markus Dahlweid, Jan Peleska
Abstract Software developed according to DO-178C Level A has to undergo extremely rigorous structural coverage analysis to ensure that the code has been adequately exercised during requirements-based testing. The goal of structural coverage analysis is either to show that the requirements-based tests are adequate, or to provide analysis data, which leads to a refinement of the tests. This paper focuses on two particular issues of structural coverage analysis, namely source-code-to-object-code traceability analysis and data coupling and control coupling analysis, both of which have been challenging in the past due to little tool support. We present details of two tools: the RT-Tester Source-Code-To-Object-Code Traceability Analyzer (RTT-STO) and the RT-Tester Data & Control Coupling Analyzer (RTT-DCC), which we have developed for the low-level verification of an Airbus avionic control system, and discuss our practical experiences with tool-supported structural coverage analysis.
2015-09-15
Technical Paper
2015-01-2471
Alessandro Ceruti, Simone Curatolo, Alessandro Bevilacqua, Piergiovanni Marzocca
Abstract The maturity reached in the development of Unmanned Air Vehicles (UAVs) systems is making them more and more attractive for a vast number of civil missions. Clearly, the introduction of UAVs in the civil airspace requiring practical and effective regulation is one of the most critical issues being currently discussed. As several civil air authorities report in their regulations “Sense and Avoid” or “Detect and Avoid” capabilities are critical to the successful integration of UAV into the civil airspace. One possible approach to achieve this capability, specifically for operations beyond the Line-of-Sight, would be to equip air vehicles with a vision-based system using cameras to monitor the surrounding air space and to classify other air vehicles flying in close proximity. This paper presents an image-based application for the supervised classification of air vehicles.
2015-09-15
Technical Paper
2015-01-2478
Tobias Kreitz, Riko Bornholdt, Matthias Krings, Karsten Henning, Frank Thielecke
Abstract The paradigm shift to focus on an enhancement of existing aircraft systems raises the question which of the many possible incremental improvements results in an advantageous solution still considering all existing requirements. Hence, new methodologies for aircraft system design are a prerequisite to cope with such huge and complex design spaces. In the case of flight control system optimization, major design variables are the control surface configuration and actuation as well as their functional allocation. Possible architecture topologies have to be verified inter alia with respect to system safety requirements. In this context, flight dynamic characteristics and handling qualities of the fully operational as well as of several degraded system states of each topology have to be evaluated and checked against common specifications. A model-based verification of the requirements is favorable, resulting in a rapid reduction of the design space.
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