Anomaly detection is an important problem that has been researched within diverse research areas and application domains. Many anomaly detection techniques have been specifically developed for certain application domains, while others are more generic. This survey tries to provide a structured and comprehensive overview of the research on anomaly detection. We have grouped existing techniques into different categories based on the underlying approach adopted by each technique. For each category we have identified key assumptions, which are used by the techniques to differentiate between normal and anomalous behavior. When applying a given technique to a particular domain, these assumptions can be used as guidelines to assess the effectiveness of the technique in that domain. For each category, we provide a basic anomaly detection technique, and then show how the different existing techniques in that category are variants of the basic technique. This template provides an easier and more succinct understanding of the techniques belonging to each category. Further, for each category, we identify the advantages and disadvantages of the techniques in that category. We also provide a discussion on the computational complexity of the techniques since it is an important issue in real application domains. We hope that this survey will provide a better understanding of the different directions in which research has been done on this topic, and how techniques developed in one area can be applied in domains for which they were not intended to begin with.

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Anomaly detection: A survey

A review of shape memory alloy research, applications and opportunities

Numerical Initial Value Problems in Ordinary Differential Equations

Novelty detection: a review—part 1: statistical approaches

With the increasing advances in hardware technology for data collection, and advances in software technology (databases) for data organization, computer scientists have increasingly participated in the latest advancements of the outlier analysis field. Computer scientists, specifically, approach this field based on their practical experiences in managing large amounts of data, and with far fewer assumptions the data can be of any type, structured or unstructured, and may be extremely large. Outlier Analysisis a comprehensive exposition, as understood by data mining experts, statisticians and computer scientists. The book has been organized carefully, and emphasis was placed on simplifying the content, so that students and practitioners can also benefit. Chapters will typically cover one of three areas: methods and techniques commonly used in outlier analysis, such as linear methods, proximity-based methods, subspace methods, and supervised methods; data domains, such as, text, categorical, mixed-attribute, time-series, streaming, discrete sequence, spatial and network data; and key applications of these methods as applied to diverse domains such as credit card fraud detection, intrusion detection, medical diagnosis, earth science, web log analytics, and social network analysis are covered.

Outlier Analysis

Engineering design processes often use optimization strategies, which aim to minimize multi-objective functions. The analysis should consider the uncertainty in a system, which may cause significan...

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Enhanced Evolutionary-Based Optimization Techniques Applied to a Nonlinear Landing Gear Design Problem

A method is proposed for the modelling of the multiple mode response of geometrically nonlinear plates and panels to random acoustic excitation. Significant savings in computational time can be achieved compared with the direct integration nonlinear finite element method (FEM). The proposed technique identifies the nonlinear stiffness terms in a reduced basis modal dynamic model by performing a regression analysis upon a number of static nonlinear finite element test cases. Regression analysis is also used to identify an empirical relationship between modal displacements and point stresses, allowing the technique to encompass stress / strain analysis. Time domain numerical integration is then used to simulate the kinematic, and stress response to band limited random acoustic excitation. Comparison with time domain finite element numerical simulations of nonlinear plates and stiffened panels shows that stress and displacement responses are predicted accurately in all cases.

Finite Element / Modal Technique for Non-linear Plate and Stiffened Panel Response Prediction

The Fish Bone Active Camber (FishBAC) is a compliance-based morphing trailing edge device that represents an alternative to traditional trailing edge hinged control surfaces. Capable of generating large, smooth and continuous changes in camber (i.e. without gaps and/or surface discontinuities), the FishBAC has the potential to reduce aircraft fuel consumption and noise. To predict the structural and aerodynamic behaviour of this device, a fluid-structure interaction (FSI) routine – based on a MindlinReissner Plate structural model and a coupled, viscous corrected 2D panel method and 3D lifting line aerodynamic model – has been developed. This paper presents a design case study where this FSI model is used to study the FishBAC’s capability to control spanwise aerodynamic loads.

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Progress on the Design of a Composite FishBAC Morphing Device for Spanwise Lift Control

: This report describes an experimental study involving the implementation of the method of receptances to control binary flutter in a wind-tunnel aerofoil rig. The aerofoil and its suspension were designed as part of the project. The advantage of the receptance method over conventional state-space approaches is that it is based entirely on frequency response function measurements, so that there is no need to know or to evaluate the system matrices describing structural mass, aeroelastic and structural damping and aeroelastic and structural stiffness. There is no need for model reduction or the estimation of unmeasured states, for example by the use of an observer. It is demonstrated experimentally that a significant increase in the flutter margin can be achieved by separating the frequencies of the heave and pitch modes. In the test carried out so far it has been found that simply increasing the damping, principally of the heave mode, is less effective in increasing the flutter margin than separating the heave and pitch frequencies.

http://www.dtic.mil/dtic/tr/fulltext/u2/a571493.pdf

Extension of Flutter Boundaries Using In-Flight Receptance Data

This paper presents a study into the occurrence of aeroelastic flutter in a high aspect ratio wing using numerical continuation and a geometrically nonlinear beam model. This beam model comprises a continuous, assumed-shape formulation and is coupled with strip theory aerodynamics. Out-of-plane, in-plane and torsional stiffness properties are varied and their influences on the flutter point are observed. A nonlinear lift curve is incorporated so as to illustrate the influence of stall effects. The occurrence of a subcritical Hopf bifurcation is also demonstrated, indicating the possibility of oscillation at airspeeds below the flutter velocity, given a sufficient wing perturbation.

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Jonathan E. Cooper

Papers

Enhanced Evolutionary-Based Optimization Techniques Applied to a Nonlinear Landing Gear Design Problem

Finite Element / Modal Technique for Non-linear Plate and Stiffened Panel Response Prediction

Progress on the Design of a Composite FishBAC Morphing Device for Spanwise Lift Control

Extension of Flutter Boundaries Using In-Flight Receptance Data

Flutter in High Aspect Ratio Wings using Numerical Continuation