Search results for "Aerospace engineering"

Aircraft wing rock oscillations suppression by simple adaptive control

2020

Abstract Roll angular motion of the modern aircraft operating in non-linear flight modes with a high angle of attack often demonstrates the limit cycle oscillations, which is commonly known as the wing rock phenomenon. Wing rock dynamics are represented by a substantially non-linear model, with parameters varying over a wide range, depending on the flight conditions (altitude, Mach number, payload mass, etc.) and angle of attack. A perspective approach of the wing rock suppression lies in the adaptation methods. In the present paper an application of the simple adaptive control approach with the Implicit Reference Model (IRM) is proposed and numerically studied. The IRM adaptive controller …

On the Measurement and Prediction of the Out-of-Plane Displacement Surrounding Cold-Expanded Holes

2010

Experimental measurements of the out-of-plane displacement surrounding cold-expanded holes in a 6082-T6 aluminum alloy were made with a 3D optical scanner using the technique of the encoded light-pattern projection in white light. The measured surface profiles have shown the thickness discontinuity along the hole edge due to the effect of the split in the sleeve. An analytical–numerical solution of the out-of-plane displacement is presented based on existing analytical models. Thus, the results given by the analytical model were then compared with the experimental data and with a finite element (FE) model that simulates the cold-expansion process. The location of the elastic–plastic boundar…

Dynamic routing-and-inventory problems: a review

1998

The paper presents a review of the available literature on a class of problems denoted as dynamic routing-and-inventory (DRAI) problems. They are characterized by the simultaneous relevance of routing and of inventory issues in a dynamic environment, within the framework of distribution logistics. A classification scheme is first proposed for these problems. Then the results obtained in this area are summarized. Finally, the papers available in the literature are clustered and discussed according to the proposed scheme.

Measurement of residual stresses by the hole-drilling method: General stress-strain relationship and its solution

1990

Direct Derivation of Corrective Terms in SDE Through Nonlinear Transformation on Fokker–Planck Equation

2004

This paper examines the problem of probabilistic characterization of nonlinear systems driven by normal and Poissonian white noise. By means of classical nonlinear transformation the stochastic differential equation driven by external input is transformed into a parametric-type stochastic differential equation. Such equations are commonly handled with Ito-type stochastic differential equations and Ito's rule is used to find the response statistics. Here a different approach is proposed, which mainly consists in transforming the Fokker–Planck equation for the original system driven by external input, in the transformed probability density function of the new state variable. It will be shown …

The Politicisation of Banking

1985

Growing government intervention in the international currency markets has distorted incentives and disguised risks. Rodney Atkinson, formerly an economist with Grindlay's Bank, argues that increasing state interference has led bankers to respond to political, not commercial, signals. Many bankers are now rewarded according to their ability to ‘work the system’ rather than for economic expertise.

A new radiation infrastructure for the Modular Earth Submodel System (MESSy, based on version 2.51)

2016

Abstract. The Modular Earth Submodel System (MESSy) provides an interface to couple submodels to a basemodel via a highly flexible data management facility (Jöckel et al., 2010). In the present paper we present the four new radiation related submodels RAD, AEROPT, CLOUDOPT and ORBIT. The submodel RAD (with shortwave radiation scheme RAD_FUBRAD) simulates the radiative transfer, the submodel AEROPT calculates the aerosol optical properties, the submodel CLOUDOPT calculates the cloud optical properties, and the submodel ORBIT is responsible for Earth orbit calculations. These submodels are coupled via the standard MESSy infrastructure and are largely based on the original radiation scheme of …

Higher order statistics of the response of MDOF linear systems under polynomials of filtered normal white noises

1997

This paper exploits the work presented in the companion paper in order to evaluate the higher order statistics of the response of linear systems excited by polynomials of filtered normal processes. In fact, by means of a variable transformation, the original system is replaced by a linear one excited by external and linearly parametric white noise excitations. The transition matrix of the new enlarged system is obtained simply once the transition matrices of the original system and of the filter are evaluated. The method is then applied in order to evaluate the higher order statistics of the approximate response of nonlinear systems to which the pseudo-force method is applied.

Asynchronous sensor fusion of GPS, IMU and CAN-based odometry for heavy-duty vehicles

2021

[EN] In heavy-duty vehicles, multiple signals are available to estimate the vehicle's kinematics, such as Inertial Measurement Unit (IMU), Global Positioning System (GPS) and linear and angular speed readings from wheel tachometers on the internal Controller Area Network (CAN). These signals have different noise variance, bandwidth and sampling rate (being the latter, possibly, irregular). In this paper we present a non-linear sensor fusion algorithm allowing asynchronous sampling and non-causal smoothing. It is applied to achieve accuracy improvements when incorporating odometry measurements from CAN bus to standard GPS+IMU kinematic estimation, as well as the robustness against missing da…

Capacity Analysis in Downlink WCDMA Systems Using Soft Handover Techniques With SIR-Based Power Control and Site Selection Diversity Transmission

2006

This work analyzes the downlink performance of a WCDMA system with site selection diversity transmission power control (SSDT) during soft handover mode. Signal to interference ratio (SIR) power control techniques are modeled and used in the simulations of this analysis. The study is focused on finding the optimum soft handover margin in terms of maximum system capacity under energy-per-bit to noise spectral density ratio (Eb/N0) quality requirements. The results of this analysis show an increase in user capacity of about 15 -20 % for optimum soft handover margins of 5 – 5.5 dB. Nevertheless, the resources required (number of scrambling codes) by base station increase faster than the number …