Search results for "Linear"
showing 10 items of 7165 documents
Fast and Accurate Bounds on Linear Programs
2009
We present an algorithm that certifies the feasibility of a linear program while using rational arithmetic as little as possible. Our approach relies on computing a feasible solution of the linear program that is as far as possible from satisfying an inequality at equality. To realize such an approach, we have to detect the set of inequalities that can only be satisfied at equality. Compared to previous approaches for this problem our algorithm has a much higher rate of success.
Certifying feasibility and objective value of linear programs
2012
Abstract We present an algorithm that certifies the feasibility of a linear program and computes a safe bound on its objective value while using rational arithmetic as little as possible. Our approach relies on computing a feasible solution that is as far as possible from satisfying an inequality at equality. To this end, we have to detect the set of inequalities that can only be satisfied at equality. Compared to previous approaches, our algorithm has a much higher success rate.
Black-Box Solvers
2017
Linear programming is perhaps the best-known tool for optimization. Linear programming is a general-purpose framework that allows a real system to be abstracted as a model with a linear objective function subject to a set of linear constraints.
Discrete-time static output-feedback semi-decentralized H<inf>&#x221E;</inf> controller design: An application to structural vibratio…
2012
In this work, we present a new and effective method to design discrete-time static output-feedback H ∞ controllers. This new method, based on a Linear Matrix Inequality (LMI) formulation, introduces a suitable transformation of the LMI variables that allows to obtain an explicit expression for the output-feedback gain matrix. Moreover, for problems involving a set of subsystems with information exchange constraints, a convenient structure on the LMI variables can be imposed in order to design semi-decentralized controllers, where the corresponding output-feedback gain matrix has a prescribed zero-nonzero structure. To illustrate the proposed methodology, discrete-time static velocity-feedba…
Approximation of Feasible Parameter Set in worst case identification of block-oriented nonlinear models
2003
Abstract The estimation of the Feasible Parameter Set for block-oriented nonlinear models in a worst case setting is considered. A bounding procedure is determined both for polytopic and ellipsoidie sets, consisting in the projection of the FPS ⊂ R MN of the extended parameter vector onto suitable M or N-dimensional subspaces and in the solution of convex optimization problems which provide the extreme points of the Parameter Uncertainties Intervals of the model parameteres. Bounds obtained are tighter then in the previous approaches.
Testing Independence: A New Approach
2000
In time series analysis and modelling, testing for independence allows us to determine if the estimated model is correctly specified. In this work, we present a very simple method to test for serial independence, based on the two-dimensional embedding vectors (the so-called “2-histories”), and we analyse the power and size of such a procedure against a wide set of linear and nonlinear alternatives.
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…
Artificial neural network applied to the discrimination of antibacterial activity by topological methods
2000
Abstract A new topological method that makes it possible to discriminate the active and inactive molecules on the basis of their chemical structures is applied in the present study to the antibacterial agents. This method uses neural networks in which training algorithms are used as well as different concepts and methods of artificial intelligence with a suitable set of topological descriptors. It is possible to obtain a QSAR interpretation of the information contained in the network after the training has been carried out.
Multiple Non-linear Reservoirs to Model Water Balance Components in Sandy Soils
2023
In the hydrologic literature, to model water flow in unsaturated soils, the Richards equation is usually applied, allowing the main components of the hydrologic cycle, as rainfall partitioning into surface runoff and infiltration, to be determined. The Richards equation is highly nonlinear, making very challenging to derive analytical solutions. Recently, for constant rainfall intensity, under the simplified hypothesis of gravity-driven infiltration, and by assuming a capacitance framework, a simplified solution of the Richards equation that considers the Brooks and Corey hydraulic conductivity function was suggested. By maintaining the assumption that the infiltration process is dominated …
Indagini di laboratorio sui composti che inducono l'aggregazione delle neanidi di I età in Leptoglossus occidentalis (Hemiptera, Coreidae)
2011
Leptoglossus occidentalis è una cimice che si alimenta degli strobili e dei semi delle conifere appartenenti alla famiglia delle Pinaceae. Le neanidi di I età hanno un comportamento gregario che favorisce la sopravvivenza degli individui, in analogia a quanto visto in altre specie appartenenti allo stesso genere (Wheeler et al., 1990). L’individuazione dei composti semiochimici che influenzano questo comportamento potrebbe portare allo sviluppo di nuovi metodi di controllo di L. occidentalis. Le estrazioni (whole body) sono state realizzate su gruppi di 7-27 neanidi di I età per 30 minuti utilizzando un quantitativo di 40µl di esano o di acetone per neanide. Gli estratti sono stati biosaggi…