Explore the vast range of titles available.

The robust stabilization problem with respect to both dynamic and parametric uncertainty for linear deterministic systems is analyzed in the present article. The robust design methods consider either the dynamic modelling in frequency domain of the uncertainty or, its parametric representation in the state space realisation. Suitable analysis approaches for parametric uncertainty modelling are provided by Kharitonov and Edge-type theorems. Under some specific assumptions, these methods allow to determine the whole admissible domain of the uncertain parameters for which a system is stable. It shall describe a method that combines the advantages of the control techniques with ones given by the polytopic representation of parametric uncertainty. A modified ∞ loop-shaping approach allowing to solve control problems in which robust stabilization, sensitivity reduction, and model following design objectives are formulated is presented and it allows to handle tracking design specifications. The modified loop-shaping procedure allows to design a controller that provides a) robust stability with respect to the normalized left coprime factorization (NLCF); b) reduced sensitivity with respect to output disturbance on a specified range of frequencies, and c) tracking of the output of a given ideal model. The article is finished with a case study in which a two degrees-of-freedom control system with respect to the pitch angle for the longitudinal dynamics of a UAV (ARCHER V1.7) is designed using the modified ∞ loop-shaping procedure.

The existing analytical methods for determining and correcting the effect of wind tunnel walls on experimental data are based on the hypothesis of potential flow. A useful simplification of the boundary conditions used to describe the perforated walls was to consider the wall as homogeneous, the solid and free portions not being treated separately, but as an equivalent permeable surface. The approximation of the wall behaviour during the experiment was possible by defining a porosity parameter. The purpose of this paper is to estimate the porosity parameter for the perforated walls of a trisonic wind tunnel by evaluating the pressure distributions measured on the walls of the test section.

This paper presents atmospheric turbulence as an intrinsic hazard to aircraft flight dynamics, particularly when flying over large oceanic expanses bodies of water such as the Pacific Ocean. This study applies the von Kármán atmospheric turbulence model to the lateral, longitudinal, and vertical perturbations experienced by a medium-range twin-engine passenger aircraft. Mathematical expressions for the turbulence inputs are derived and integrated into the linearised aircraft equations of motion, and the dynamic response under cruise flight conditions is analysed. The results reveal key insights into turbulence structure and demonstrate the utility of stochastic filtering for state estimation in high-noise environments.

In order to obtain accurate results in wind tunnel testing it is necessary to determine the effect of interaction between the flow around the model and the test section walls. In this paper, the classical theory for wind tunnel wall corrections assessment is used to evaluate the wall induced change in the circulation caused by the presence of the test article in the wind tunnel. This primary correction, also known as lift interference is based on the test section geometry and it is applied to the test article angle of attack. The computations performed in this paper employ the assumption of the potential linearized flow between the test section walls and the model. As well, the principle of superposition is a key element in this analysis.

Earthquakes are one of the most destructive natural phenomena in the world, their impact being of particular severity in urban areas. Failures relating to proper allocation of resources, to the identification of optimal routes between the affected urban areas and relief centres, and to the mitigation of potential earthquake-triggered destructive phenomena emerge as systemic vulnerability sources. This paper aims to assess the seismic systemic vulnerability of the 6 administrative centres in the South-East region of Romania, by proposing a weighted composite index (Earthquake Vulnerability Index, ESVI) that integrates indicators referring to the accessibility of emergency services centres, the capacity of the local medical infrastructure and secondary danger sources. The validation of ESVI relies on Sensitivity Analysis and Multi-Criteria Decision-Making (MCDM) methods. Moreover, in order to illustrate the utility of an assessment of this type, a comparative case study of Galați and Brăila Cities is presented. This paper shows how the integration of GIS tools and techniques may improve vulnerability assessments, especially when they are used in conjunction with MCDM methods. ESVI and its integrated maps point out the most vulnerable urban centres and the hotspots of vulnerability within them, allowing for advanced regional and local scale planning of emergency interventions.