Search results for "Stability"
showing 10 items of 3085 documents
Stabilization of discrete-time systems with stochastic sampling
2012
This paper is concerned with the stabilization problem of discrete-time systems with stochastic sampling. It is assumed that there are a single-rate sampling in the plant input and two stochastic sampling rates in the controller input whose occurrence probabilities are given constants and satisfy a Bernoulli distribution. By Lyapunov function approach, a new sufficient condition is presented for the mean square asymptotic stability of the system. Based on this, the design procedure for stabilization controllers is proposed. Finally, an example is given to demonstrate the effectiveness of the proposed techniques.
Path Integral Method for Nonlinear Systems Under Levy White Noise
2017
In this paper, the probabilistic response of nonlinear systems driven by alpha-stable Lévy white noises is considered. The path integral solution is adopted for determining the evolution of the probability density function of nonlinear oscillators. Specifically, based on the properties of alpha-stable random variables and processes, the path integral solution is extended to deal with Lévy white noises input with any value of the stability index alpha. It is shown that at the limit when the time increments tend to zero, the Einstein–Smoluchowsky equation, governing the evolution of the response probability density function, is fully restored. Application to linear and nonlinear systems under…
Impact of hydrothermal ageing on the thermal stability, morphology and viscoelastic performance of PLA/sisal biocomposites
2016
The influence of the combined exposure to water and temperature on the behaviour of polylactide/sisal biocomposites coupled with maleic acid anhydride was assessed through accelerated hydrothermal ageing. The biocomposites were immersed in water at temperatures from 65 to 85 °C, between the glass transition and cold crystallisation of the PLA matrix. The results showed that the most influent factor for water absorption was the percentage of fibres, followed by the presence of coupling agent, whereas the effect of the temperature was not significant. Deep assessment was devoted to biocomposites subjected to hydrothermal ageing at 85 °C, since it represents the extreme degrading condition. Th…
A Quantitative Biophysical Principle to Explain the 3D Cellular Connectivity in Curved Epithelia
2021
Epithelial cell organization and the mechanical stability of tissues are closely related. In this context, it has been recently shown that packing optimization in bended/folded epithelia is achieved by a surface tension energy minimization mechanism that leads to a novel cellular shape: the scutoid. However, further cellular and tissue level implications of this new developmental paradigm remain unknown. Here we focus on the relation of this complex cellular shape and the connectivity between cells. We address this problem using a combination of computational, experimental, and biophysical approaches in tubular epithelia. We dissect the contribution of the energetic drivers inducing the com…
Harmonic Balance Method and Stability of Discontinuous Systems
2019
The development of the theory of discontinuous dynamical systems and differential inclusions was not only due to research in the field of abstract mathematics but also a result of studies of particular problems in mechanics. One of the first methods, used for the analysis of dynamics in discontinuous mechanical systems, was the harmonic balance method developed in the thirties of the twentieth century. In our work, the results of analysis obtained by the method of harmonic balance, which is an approximate method, are compared with the results obtained by rigorous mathematical methods and numerical simulation.
Phasenumwandlungen in Korrosionsschichten auf Eisen: Mößbauerspektroskopische Untersuchungen
1981
Zur Untersuchung der Korrosion von Stahlblechen wurde die mosbauerspektroskopische Phasenanalyse in Transmissions- und Streugeometrie eingesetzt. Die Korrosion von Stahlblechen fuhrt in einer Atmosphare von geringer Korrosivitat nach langen Expositionszeiten vorwiegend zu den relativ stabilen β-Phasen der moglichen Fe-Korrosionsprodukte. Bei durch HCl-Zusatz erhohter Korrosivitat ergibt sich eine Bevorzugung der Bildung von β-FeOOH und kein Auftreten der α-Phasen. Auch der Einflus von. Beschichtungen auf die Phasenzusammensetzung wird behandelt. Die Entstehung und Umwandlung der verschiedenen Fe-haltigen Phasen im Rost last sich anhand eines Stabilitatsdiagramms verstehen. Auch die Wirkung …
Convergence in critical fuel moisture and fire weather thresholds associated with fire activity in the pyroregions of Mediterranean Europe
2021
Wildfires are becoming an increasing threat to many communities worldwide. There has been substantial progress towards understanding the proximal causes of increased fire activity in recent years at regional and national scales. However, subcontinental scale examinations of the commonalities and differences in the drivers of fire activity across different regions are rare in the Mediterranean zone of the European Union (EUMed). Here, we first develop a new classification of EUMed pyroregions, based on grouping different ecoregions with similar seasonal patterns of burned area. We then examine the thresholds associated with fire activity in response to different drivers related to fuel moist…
Relationship of Weather Types on the Seasonal and Spatial Variability of Rainfall, Runoff, and Sediment Yield in the Western Mediterranean Basin
2020
Producción Científica
Supported Liquid Membranes and Their Modifications
2010
Publisher Summary This chapter discusses the principle, kinetic and transport mechanisms, stability of supported liquid membrane (SLM) design followed by thier configuration. In the examples of SLM applications presented in this chapter, the possibility to separate high quantities of compounds using small volumes of organic phases shows that this method is still a very attractive choice when an efficient and selective method is necessary. Also, as a result of the development and commercialization of hydrophobic hollow-fiber membrane contactors, SLM might be applied successfully for industrial purposes. This is due to the high-membrane surface per unit of volume with satisfactory liquid memb…
Morphology, interfacial interaction, and thermal degradation of polycarbonate/MCM-41 (nano)composites
2017
ABSTRACTThis article reports on the morphology, interfacial interaction, thermal stability, and thermal degradation kinetics of polycarbonate (PC)/mesoporous silica (MCM-41) composites with various MCM-41 contents, prepared by melt compounding. The composites with low filler loadings (<0.3 wt%) maintained their transparency because of the well dispersed MCM-41 particles, but at higher filler loadings the composites lost their transparency due to the presence of agglomerates. The presence of agglomerates decreased the thermal stability of PC due to the reduced effectiveness of the particles to immobilize the polymer chains, free radicals, and volatile degradation products.