Search results for "APT"

Finite-time stability and stabilisation for a class of nonlinear systems with time-varying delay

2014

This paper is concerned with the problems of finite-time stability FTS and finite-time stabilisation for a class of nonlinear systems with time-varying delay, which can be represented by Takagi–Sugeno fuzzy system. Some new delay-dependent FTS conditions are provided and applied to the design problem of finite-time fuzzy controllers. First, based on an integral inequality and a fuzzy Lyapunov–Krasovskii functional, a delay-dependent FTS criterion is proposed for open-loop fuzzy system by introducing some free fuzzy weighting matrices, which are less conservative than other existing ones. Then, the parallel distributed compensation controller is designed to ensure FTS of the time-delay fuzzy…

Automatic Take Off and Landing for UAS Flying in Turbulent Air - An EKF Based Procedure

2020

An innovative use of the Extended Kalman Filter (EKF) is proposed to perform automatic take off and landing by the rejection of disturbances due to turbulence. By using two simultaneously working Extended Kalman Filters, a procedure is implemented: the first filter, by using measurements gathered in turbulent air, estimates wind components; the second one, by using the estimated disturbances, obtains command laws that are able to reject disturbances. The fundamental innovation of such a procedure consists in the fact that the covariance matrices of process (Q) and measurement (R) noise are not treated as filter design parameters. In this way determined optimal values of the aforementioned m…

Image Enhancement Algorithm for Optical Microstructural Characterization of Shape Memory TiNi Friction Stir Processed

2017

Abstract A key topic regarding TiNi alloys concerns the possibility to attain junctions that preserve the shape memory properties of material. Experimental tests, previously performed on TiNi sheet friction stir processed, have highlighted the need to develop an appropriate image analysis method to quantify the various phases percentages present in the characteristics zones of Friction Stir Welding process. A proper Image Processing procedure has been performed in order to quantify the amount of the martensitic phase and to detect its morphology modification along to the processed region. Particularly each micrographic image, firstly, has been denoised using the 2D Wavelet transform techniq…

Optimal control of discrete-time interval type-2 fuzzy-model-based systems with D-stability constraint and control saturation

2016

This paper investigates the optimal control problem for discrete-time interval type-2 (IT2) fuzzy systems with pole constraints. An IT2 fuzzy controller is characterized by two predefined functions, and the membership functions and the premise rules of the IT2 fuzzy controller can be chosen freely. The pole assignment is considered, which is constrained in a presented disk region. Based on Lyapunov stability theory, sufficient conditions of asymptotic stability with an H ∞ performance are obtained for the discrete-time IT2 fuzzy model based (FMB) system. Based on the criterion, the desired IT2 state-feedback controller is designed to guarantee that the closed-loop system is asymptotically s…

Adaptive Fuzzy Super-Twisting Sliding Mode Control for Microgyroscope

2019

This paper proposes a novel adaptive fuzzy super-twisting sliding mode control scheme for microgyroscopes with unknown model uncertainties and external disturbances. Firstly, an adaptive algorithm is used to estimate the unknown parameters and angular velocity of microgyroscopes. Secondly, in order to improve the performance of the system and the superiority of the super-twisting algorithm, this paper utilizes the universal approximation characteristic of the fuzzy system to approach the gain of the super-twisting sliding mode controller and identify the gain of the controller online, realizing the adaptive adjustment of the controller parameters. Simulation results verify the superiority a…

The magnitude of a product recall: offshore outsourcing vs. captive offshoring effects

2018

The escalation in product recalls in recent years is attributed to the rise of globalisation and associated challenges of offshoring. Extant SCM research suggests that product recalls have a significant negative impact on financial performance, but gaps exist relative to the managerial actions to minimise their impact. Recall response strategies have become more important in the press, given that a single recall may result in the mandatory withdrawal of millions of products from the market, with firms incurring enormous logistics costs and brand damage. In this study, we address this gap in the research, and using a measure of product recall defined as the volume of products withdrawn from …

Variable neighborhood descent for the incremental graph drawing

2017

Abstract Graphs are used to represent reality in several areas of knowledge. Drawings of graphs have many applications, from project scheduling to software diagrams. The main quality desired for drawings of graphs is readability, and crossing reduction is a fundamental aesthetic criterion for a good representation of a graph. In this paper we target the edge crossing reduction in the context of incremental graph drawing, in which we want to preserve the layout of a graph over successive drawings. We propose a hybrid method based on the GRASP (Greedy Randomized Adaptive Search Procedure) and VND (Variable Neighborhood Descent) methodologies and compare it with previous methods via simulation.

Climate Change and Disasters

2017

Ideas and approaches proven successful within disaster risk reduction (DRR) literature and practice are either bypassed or inadequately considered by contemporary climate change work. This chapter explores the intersections between climate change and hazards, vulnerability, and risk, looking at climate change as both a hazard driver and a hazard inhibitor. The implications of the narrow interpretations of vulnerability employed in climate change work are examined, as well as the ways in which climate change has come to act as a scapegoat for issues, events, and processes caused by hazard-independent factors. The chapter formulates a case for climate change adaptation (CCA) to be seen as a s…

Landslide Hazards and Climate Change Adaptation of Transport Infrastructures in Germany

2017

Helices of disaster memory: How forgetting and remembering influence tropical cyclone response in Mauritius

2020

Abstract Tropical cyclones have had a considerable impact on Mauritius. Large cyclones are relatively rare, and in popular imagination are thought to hit Mauritius every 15 years. Yet it has been over 25 years since the last cyclone widely considered as ‘significant’. Critically, there is little known about the role of memory in responses to cyclones and details regarding responses to past cyclones in Mauritian history are scant. This article examines past experiences and impacts of cyclones in Mauritius, as well as contemporary perceptions of cyclone vulnerability and memories of historical cyclones. The analysis draws on both community interviews and archival research conducted in Mauriti…