Search results for "Equations"
showing 10 items of 955 documents
A closed-form solution for natural frequencies of thin-walled cylinders with clamped edges
2016
Abstract This paper presents an approximate closed-form solution for the free-vibration problem of thin-walled clamped–clamped cylinders. The used indefinite equations of motion are classic. They derive from Reissner׳s version of Love׳s theory, properly modified with Donnell׳s assumptions, but an innovative approach has been used to find the equations of natural frequencies, based on a solving technique similar to Rayleigh׳s method, on the Hamilton׳s principle and on a proper constructions of the eigenfuctions. Thanks to the used approach, given the geometric and mechanical characteristics of the cylinder, the model provides the natural frequencies via a sequence of explicit algebraic equat…
A correction method for dynamic analysis of linear continuous systems
2005
A method to improve the dynamic response analysis of continuous classically damped linear system is proposed. As in fact usually, following a classical approach, a reduced number of eigenfunctions are accounted for and the response is evaluated by integrating the uncoupled differential equations of motion in modal space, neglecting the contribution of high frequency modes (truncation procedure). Here, starting from the given system, it is proposed to set up two differential equations governing the motion of two new continuous systems: the first one contains only the first m non-zero eigenvalues of the given system and the second one contains the remainder non-zero infinity - m eigenvalues. …
STUDY OF LEG MOVEMENT IN ONE- AND TWO-LEGGED HOPPING
2012
This study was based on the previous research where mechanics of the leg-pushing phase in shot put was studied. The present paper examined the functional mechanics of leg movements during the ground contact of the jumps on one leg and on two legs. The principle of the measuring method was to photograph the movement in series of subject images on one frame where the marker lights attached to the subject can be seen as broken light-lines. The measuring accuracy of the system (time and distance) proved to be very high. This new measuring method is a useful complement to the existing methods. The aim of the study was to approximate the measured points by a suitable curve. Two equations (represe…
The Kp Hierarchy
1989
As an application of the theory of infinite-dimensional Grassmannians and the representation theory of gl1 we shall study in this chapter certain nonlinear “exactly solvable” systems of differential equations. Exactly solvable means here that the nonlinear system can be transformed to an (infinite-dimensional) linear problem. A prototype of the equations is the Korteweg-de Vries equation $$\frac{{\partial u}}{{\partial t}} = \frac{3}{3}u\frac{{\partial u}}{{\partial x}} + \frac{1}{4}\frac{{{\partial ^3}u}}{{\partial {x^3}}}$$ . It turns out that it is more natural to consider an infinite system of equations like that above, for obtaining explicit solutions. The set of equations is called th…
Evaluating the performance of reference evapotranspiration equations with scintillometer measurements under Mediterranean climate and effects on oliv…
2014
The concept of reference potranspiration is widely used to support water resource management in agriculture and for irrigation scheduling, especially under arid and semi-arid conditions. The Penman-Monteith standardized formulations, as suggested by ASCE and FAO-56 papers, are generally applied for accurate estimations of ETo, at hourly and daily scale. When detailed meteorological information are not available, several alternative and simplified equations, using a limited number of variables, have been proposed (Blaney-Criddle, HargreavesSamani, Turc, Makkinen and Pristley-Taylor). In this paper, scintillometer measurements collected for six month in 2005, on an experimental plot under “re…
An order-adaptive compact approximation Taylor method for systems of conservation laws
2021
Abstract We present a new family of high-order shock-capturing finite difference numerical methods for systems of conservation laws. These methods, called Adaptive Compact Approximation Taylor (ACAT) schemes, use centered ( 2 p + 1 ) -point stencils, where p may take values in { 1 , 2 , … , P } according to a new family of smoothness indicators in the stencils. The methods are based on a combination of a robust first order scheme and the Compact Approximate Taylor (CAT) methods of order 2p-order, p = 1 , 2 , … , P so that they are first order accurate near discontinuities and have order 2p in smooth regions, where ( 2 p + 1 ) is the size of the biggest stencil in which large gradients are n…
Stochastic dynamics and mean field approach in a system of three interacting species
2008
The spatio-temporal dynamics of three interacting species, two preys and one predator, in the presence of two different kinds of noise sources is studied. To describe the spatial distributions of the species we use a model based on Lotka-Volterra equations. A correlated dichotomous noise acts on \beta, the interaction parameter between the two preys, and a multiplicative white noise affects directly the dynamics of each one of the three species. We study the time behaviour of the three species in single site for different values of the multiplicative noise intensity, finding noise-induced oscillations of the three species densities with an anticorrelated behaviour of the two preys. Afterwar…
Role of the Colored Noise in Spatio-Temporal Behavior of Two Competing Species
2005
We study the spatial distributions of two randomly interacting species, in the presence of an external multiplicative colored noise. The dynamics of the ecosystem is described by a coupled map lattice model. We find a nonmonotonic behavior in the formation of large scale spatial correlations as a function of the multiplicative colored noise intensity. This behavior is shifted towards higher values of the noise intensity for increasing correlation time of the noise.
Boulder dynamics in the Favignana Island coastal zone (Egadi Archipelago, Central Mediterranean)
2016
Boulders disjoined from platform edges or accumulated in the nearshore are frequently transported and deposited in the backshore as a consequence of tsunamis and high-magnitude storm waves. We investigate this process in the Favignana Island (Egadi Archipelago) coastal zone by integrating geological and morphological data with numerical hydrodynamic analysis and radiocarbon dating. Boulders and sockets are detected in proximity to the shorelines of Punta Faraglione and Punta Fanfalo, which are located in the NW and SE sectors of the Favignana Island, respectively. They are scattered on the rocky platform as isolated blocks or in small groups that, together, form a discontinuous berm. The la…
An improved five-parameter model for photovoltaic modules
2010
This paper presents a new five-parameter model capable of analytically describing the I–V characteristic of a photovoltaic module for each generic condition of operative temperature and solar irradiance. The parameters of the equivalent electrical circuit are extracted by solving a system of equations based on data commonly issued by manufacturers in standard rating conditions with a trial and error process. The procedure, which does not require any special equations solver, can be easily coded into a short software routine using simple languages and finds the solution of the system of equations with the desired accuracy without needing to be guided towards solutions starting from fitted in…