Search results for "equation"
showing 10 items of 4219 documents
Optimal Control Under Fuzzy Conditions for Dynamical Systems Associated with the Second Order Linear Differential Equations
2020
This paper is devoted to an optimal trajectory planning problem with uncertainty in location conditions considered as a problem of constrained optimal control for dynamical systems. Fuzzy numbers are used to incorporate uncertainty of constraints into the classical setting of the problem under consideration. The proposed approach applied to dynamical systems associated with the second order linear differential equations allows to find an optimal control law at each \(\alpha \)-level using spline-based methods developed in the framework of the theory of splines in convex sets. The solution technique is illustrated by numerical examples.
Fractional Derivatives in Interval Analysis
2017
In this paper, interval fractional derivatives are presented. We consider uncertainty in both the order and the argument of the fractional operator. The approach proposed takes advantage of the property of Fourier and Laplace transforms with respect to the translation operator, in order to first define integral transform of interval functions. Subsequently, the main interval fractional integrals and derivatives, such as the Riemann–Liouville, Caputo, and Riesz, are defined based on their properties with respect to integral transforms. Moreover, uncertain-but-bounded linear fractional dynamical systems, relevant in modeling fractional viscoelasticity, excited by zero-mean stationary Gaussian…
The Psychobiosocial States (PBS-S) Scale
2019
Abstract. This study examined the factor structure and reliability of the Psychobiosocial States (PBS-S) scale in the assessment of situational performance-related experiences. We administered the scale to 483 Finnish athletes before a practice session to assess the intensity and perceived impact of their performance-related feeling states. The hypothesized two-factor structure indicating functional effects (10 items) and dysfunctional effects (10 items) toward performance was examined via exploratory structural equation modeling (ESEM) and confirmatory factor analysis (CFA). Regarding the intensity and perceived impact dimensions of reported states, ESEM and CFA showed a good fit for a tw…
Study of eta K(K)over-bar and eta ' K(K)over-bar with the fixed center approximation to Faddeev equations
2013
In the present work we investigate the three-body systems of eta K (K) over bar and eta'K (K) over bar, by taking the fixed center approximation to Faddeev equations. We find a clear and stable resonance structure around 1490 MeV in the squared eta K (K) over bar scattering amplitude, which is not sensitive to the renormalization parameters. Conversely, we get only an enhancement effect of the threshold in the eta'K (K) over bar amplitude that indicates the difficulty to bind the eta'K (K) over bar system as a consequence of the eta'K interaction being weaker than the eta K one. We associate the eta K (K) over bar state found to the eta(1475).
Gluon mass generation in the presence of dynamical quarks
2013
We study in detail the impact of dynamical quarks on the gluon mass generation mechanism, in the Landau gauge, for the case of a small number of quark families. As in earlier considerations, we assume that the main bulk of the unquenching corrections to the gluon propagator originates from the fully dressed quark-loop diagram. The nonperturbative evaluation of this diagram provides the key relation that expresses the unquenched gluon propagator as a deviation from its quenched counterpart. This relation is subsequently coupled to the integral equation that controls the momentum evolution of the effective gluon mass, which contains a single adjustable parameter; this constitutes a major impr…
Time-dependent density-functional theory in the projector augmented-wave method
2008
We present the implementation of the time-dependent density-functional theory both in linear-response and in time-propagation formalisms using the projector augmented-wave method in real-space grids. The two technically very different methods are compared in the linear-response regime where we found perfect agreement in the calculated photoabsorption spectra. We discuss the strengths and weaknesses of the two methods as well as their convergence properties. We demonstrate different applications of the methods by calculating excitation energies and excited state Born–Oppenheimer potential surfaces for a set of atoms and molecules with the linear-response method and by calculating nonlinear e…
Latent force models for earth observation time series prediction
2016
We introduce latent force models for Earth observation time series analysis. The model uses Gaussian processes and differential equations to combine data driven modelling with a physical model of the system. The LFM presented here performs multi-output structured regression, adapts to the signal characteristics, it can cope with missing data in the time series, and provides explicit latent functions that allow system analysis and evaluation. We successfully illustrate the performance in challenging scenarios of crop monitoring from space, providing time-resolved time series predictions.
Revisiting the role of top-down and bottom-up controls in stabilisation of nutrient-rich plankton communities
2019
Understanding the conditions for successful control of phytoplankton by zooplankton in eutrophic ecosystems is a highly important research area with a wide implementation of mathematical modelling. Theoretical models generally predict destabilisation of food webs in eutrophic environments with large-amplitude oscillations of population densities which would eventually result in species extinction. On the other hand, these theoretical predic- tions are often at odds with ecological observations demonstrating stable dynamics even for a high nutrient load. This apparent discrepancy is known in the literature as Rosen- zweig’s “paradox of enrichment”. Recent theoretical works emphasize a crucia…
Bilateral De-Jure Exchange Rate Regimes and Foreign Direct Investment: A Gravity Analysis
2021
Abstract This paper introduces a novel dataset on bilateral de-jure exchange rate regimes. The new dataset accounts for the fact that officially pegging to one currency is uninformative about the exchange rate regime prevailing vis-a-vis other currencies, and it allows characterizing bilateral exchange rate regimes based on countries’ ex-ante announcements rather than ex-post observations. We use this data to estimate the effect of expected exchange rate volatility on foreign direct investment (FDI). Starting from a simple model that suggests that announced exchange rate stability enhances bilateral FDI flows, we provide empirical evidence that lends support to this claim: countries that ar…
EMU and trade: A PPML re‐assessment with intra‐national trade flows
2020
This paper examines the EMU effect on trade for the eleven early joiners and Greece relying for the first time on data that include both international and intra‐national trade flows, in line with all the microfoundations of the structural gravity model of trade. We find that the overall EMU impact on trade is positive between its members and, specially, for trade between members and non‐members. Interestingly, we further show that the effect of the EMU on bilateral trade remarkably differs across countries. For Ireland, Belgium–Luxembourg, Spain, Portugal and Austria, we find robust evidence that EMU has boosted trade both with other members and with third countries, while for Finland, Fran…