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Hoencamp L.A.,Netherlands Defence Academy NLDA
AIAA Atmospheric Flight Mechanics Conference 2011 | Year: 2011

The requirements for rotorcraft operations in harsh environments along with the large cost reduction in both civil and military services, and the current replacement of large numbers of airframes, are some of the challenges facing the rotorcraft industry today. These days successful completion of the qualification cycle of helicopters operating from ships is still solely dependent on actual data gathering campaigns during expensive sea trials, in which modeling and simulation is hardly used. It would be a clear advantage to have a predictive engineering tool to perform early evaluation of safety limits for operating aircraft from ships in a wide range of in-service conditions. For this reason the developed analysis tool applies maximum and minimum values of local wind conditions near the flight deck to aircraft rejection criteria stored in look-up tables to ensure that there remains sufficient power and control margin to perform safe flight operations throughout. The functionality of the software tool is diverse, although the main goal after complete validation is to certify large parts of the envelopes with very limited sea trials. © 2011 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved. Source


Hoencamp A.,Netherlands Defence Academy NLDA
Annual Forum Proceedings - AHS International | Year: 2011

The Ship Helicopter Operational Limitation qualification programs are based on a high number of independent variables causing the full operational potential to be almost impossible to achieve within the small window allowed for sea trials. It would be a clear advantage to have a predictive engineering tool to perform early evaluation of safety limits for operating aircraft from ships in a wide range of in-service conditions and so be less dependent on the results from several dedicated sea trials. For this reason a predictive analysis tool is under development based on specific rejection criteria for each helicopter type and their dependencies in the ship environment. The tool could be used for determining the Candidate Flight Envelope for each ship type, allowing larger steps in an incremental approach towards flight envelope restrictions, sensible exclusion of test points and accurate read-across between other helicopter-ship combinations. The accuracy of predictions by the analysis tool allows advanced insight into the cost effectiveness of complete sea trials and ultimately certification of large parts of the envelope with minimal sea trials. Copyright © 2011 by the American Helicopter Society International, Inc. All rights reserved. Source


Hoencamp A.,Netherlands Defence Academy NLDA | White M.D.,University of Liverpool | Perfect P.,University of Liverpool
37th European Rotorcraft Forum 2011, ERF 2011 | Year: 2011

The requirements for rotorcraft operations in harsh environments along with the large cost reduction in both civil and military services, and the current replacement of large numbers of airframes, are some of the challenges facing the rotorcraft industry today. These days successful completion of the qualification cycle of helicopters operating from ships is still solely dependent on actual data gathering campaigns during expensive sea trials, in which modeling and simulation is hardly used. It would be a clear advantage to have a predictive engineering tool to perform early evaluation of safety limits for operating aircraft from ships in a wide range of in-service conditions. For this reason the developed analysis tool applies maximum and minimum values of local wind conditions near the flight deck to aircraft rejection criteria stored in look-up tables to ensure that there remains sufficient power and control margin to perform safe flight operations throughout. A proof of concept for the predictive software tool is performed in the University of Liverpool's full motion piloted flight simulator, HELIFLIGHT-R, which consists of rotorcraft models interacting with ships airwake and ship motion models. The results of the proof of concept are very promising and presented in this paper. (Figure Presented). Source


Van Der Wal A.J.,Netherlands Defence Academy NLDA
Proceedings of 2010 IEEE International Conference on Intelligent Systems and Knowledge Engineering, ISKE 2010 | Year: 2010

One of the most challenging phenomena that can be observed in an ensemble of interacting agents is that of selforganisation, viz. emergent, collective behaviour, also known as synergy. The concept of synergy is well-known in the artificial intelligence community, in social science, and in management and economic sciences. The paradigm may be expressed by identifying an ensemble performance measure that yields more than the sum of the individual performance measures of the constituents. The aim of the present study is to discuss in a simple conceptual model system under what circumstances selforganization is feasible and to discuss what type of agents and interactions are minimally required to induce synergy among agents. As a case in point we discuss the emergent phase coherence of a multi-oscillator system with non-linear all-to-all coupling between the oscillators. In the thermodynamic limit of infinitely many interacting agents this system shows spontaneous organization. Simulations indicate that also for finite populations that are not completely connected partial phase synchronization spontaneously emerges if the interaction strength is strong enough. ©2010 IEEE. Source


Koopman P.,Radboud University Nijmegen | Plasmeijer R.,Radboud University Nijmegen | Jansen J.M.,Netherlands Defence Academy NLDA
ACM International Conference Proceeding Series | Year: 2014

From the λ-calculus it is known how to represent (recursive) data structures by ordinary λ-terms. Based on this idea one can represent algebraic data types in a functional programming language by higher-order functions. Using this encoding we only have to implement functions to achieve an implementation of the functional language with data structures. In this paper we compare the famous Church encoding of data types with the less familiar Scott and Parigot encodings. We show that one can use the encoding of data types by functions in a Hindley-Milner typed language by adding a single constructor for each data type. In an untyped context, like an efficient implementation, this constructor can be omitted. By collecting the basic operations of a data type in a type constructor class and providing instances for the various encodings, these encodings can coexist in a single program. By changing the instance of this class we can execute the same algorithm in a different encoding. This makes it easier to compare the encodings with each other. We show that in the Church encoding selectors of constructors yielding the recursive type, like the tail of a list, have an undesirable strictness in the spine of the data structure. The Scott and Parigot encodings do not hamper lazy evaluation in any way. The evaluation of the recursive spine by the Church encoding makes the complexity of these destructors linear time. The same destructors in the Scott and the Parigot encoding requires only constant time. Moreover, the Church encoding has problems with sharing reduction results of selectors. The Parigot encoding is a combination of the Scott and Church encoding. Hence we might expect that it combines the best of both worlds, but in practice it does not offer any advantage over the Scott encoding. Copyright © 2014 ACM. Source

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