1,720,974 research outputs found
Design of residual generators and adaptive filters for the FDI of aircraft model sensors
No full textThe main contribution of this paper is the description and application of a comprehensive set of
methodologies for fault detection and isolation (FDI) of aircraft sensors. In particular, a new nonlinear
geometric approach (NLGA) and an efficient linear polynomial method (PM) are presented and
compared, together with simulation results obtained from a commercial aircraft model. Adaptive filters
with disturbance decoupling for fault identification are designed via the developed NLGA-based
method. On the other hand, the FDI scheme based on linear PM exploits a disturbance decoupling
technique in connection with a linear dynamic filter design procedure. The FDI strategies are applied to
the aircraft simulator data in a flight condition characterised by tight–coupled longitudinal and lateral
dynamics. Moreover, in order to analyse robustness and reliability properties of the two FDI schemes,
extensive simulations are performed in the presence of turbulence, measurement noise and modelling
errors
Residual Generator Design and Performance Evaluation for Aircraft Simulated Model FDI
No full textIn this work, a model-based procedure exploiting
analytical redundancy for the FDI of faults on a multivariable
dynamic process is presented. The main point of the paper
consists of exploiting a disturbance decoupling scheme in
connection with a dynamic filter design procedure for diagnostic
purpose. It is shown that the suggested approach to fault
diagnosis is in particular advantageous in terms of solution
complexity and performance. Moreover, the presented method
is especially useful when robust solutions are considered for
minimising the effects of modelling errors and noise, while maximising
fault sensitivity. In order to verify the robustness of the
solution achieved, the proposed design has been experimented
with the data of a simulated aircraft model in the presence
of both measurement and modelling errors. Finally, extensive
simulations of the test-bed process and Monte Carlo analysis
are the tools used for assessing the overall capabilities of the
developed FDI scheme, when compared also with different
data-driven diagnosis methods
Residual Generator Function Design for Actuator Fault Detection and Isolation of a Piper PA30 Aircraft
No full textThis paper addresses the problem of the detection
and isolation of actuator faults on a general aviation aircraft,
characterised by a nonlinear model, in the presence of wind
gust disturbances. In particular, this work investigates the
design of residual generators in order to realise complete
diagnosis schemes when additive faults are present. The
use of a canonical input-output polynomial description for
the linearised model of the aircraft allows to compute in
a straightforward way minimal order residual generators.
These tools lead to dynamic filters that can guarantee both
disturbance signal decoupling and robustness properties with
respect to linearisation errors. The results obtained in the
simulation of the faulty behaviour of a Piper PA30 are finally
reported
Application of Fault Diagnosis Methodologies to a General Aviation Aircraft
No full textThis paper addresses the problem of the detection and isolation of
input sensor faults on a general aviation aircraft, characterised by a nonlinear
model, in the presence of wind gust disturbance and measurement errors. In
particular, this work studies and compares different residual generator designs
in order to realise complete diagnosis schemes, when additive faults are present.
These different methods comprise linear and nonlinear filters, neural networks and
unknown input Kalman filters, that can achieve disturbance signal de-coupling
and robustness properties with respect to modelling error and sensor measurement
noise. The results obtained in the simulation of the faulty behaviour of a PIPER
PA30 longitudinal aircraft model are finally reported
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Design and Performance Evaluation of Residual Generators for the FDI of an Aircraft
No full textIn this work, several procedures for the fault detection and isolation (FDI) on general aviation aircraft sensors are presented.
In order to provide a comprehensive wide-spectrum treatment, both linear and nonlinear, model-based and data-driven methodologies are considered. The main contributions of the paper are related to the development of both FDI polynomial method (PM) and FDI scheme based on the nonLinear geometric approach (NLGA). As to the PM, the obtained results highlight a good trade-off between solution complexity and resulting performances. Moreover, the proposed PM is especially useful when robust solutions are required for minimising the effects of modelling errors and noise, while maximising fault sensitivity. As to the NLGA, the proposed work is the first development and robust application of the NLGA to an aircraft model in flight conditions characterised by tight-coupled longitudinal and lateral dynamics. In order to verify the robustness of the residual generators related to the previous FDI techniques, the simulation results adopt a typical aircraft reference trajectory embedding several steady{state flight conditions, such as straight flight phases and coordinated turns. Moreover, the simulations are performed in the presence of both measurement and modelling errors. Finally, extensive simulations are used for assessing the overall capabilities of the developed FDI schemes and a comparison with neural networks (NN) and unknown input Kalman filter (UIKF) diagnosis methods is performed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
NONLINEAR ACTUATOR FAULT DETECTION AND ISOLATION FOR A GENERAL AVIATION AIRCRAFT
No full textThis paper addresses the problem of detection and isolation of actuator
faults for a general aviation aircraft, where the nonlinear simulation aircraft model
embeds the effects of wind gusts, atmospheric turbulence and measurement errors.
The approach is based on the recently introduced NonLinear Geometric Approach
(NLGA) to the Fault Detection and Isolation (FDI) problem. The actuators FDI
is performed in a coordinated turn, hence with coupled longitudinal and lateral-
directional dynamics. This work represents the first complete NLGA FDI scheme
for a general aviation aircraft in a condition with tight-coupled dynamics. The
results obtained in the simulation of the faulty behaviour of a nonlinear Piper
PA30 aircraft are finally reported
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