Search results for "OPTIMA"
showing 10 items of 735 documents
A method for determining the position and size of optimal sequence regions for phylogenetic analysis.
1995
The availability of fast and accurate sequencing procedures along with the use of PCR has led to a proliferation of studies of variability at the molecular level in populations. Nevertheless, it is often impractical to examine long genomic stretches and a large number of individuals at the same time. In order to optimize this kind of study, we suggest a heuristic procedure for detection of the shortest region whose informational content can be considered sufficient for significant phylogenetic reconstruction. The method is based on the comparison of the pairwise genetic distances obtained from a set of sequences of reference to those obtained for different windows of variable size and posit…
Control Strategy for Induction Motor Drives Based on Decoupling Techniques
1989
Abstract In this work a new closed loop, synchronous microprocessor-based controller is proposed for field oriented controlled induction motor drives, using a PWM voltage source inverter. This controller is based on a non linear state feedback compensator which gives decoupling of both rotor current and rotor flux, and direct and inquadrature components of the stator current vector. The compensator has a linearizing effect on the synchronous model of the electromagnetic circuit of the motor. It follows that the control laws can be obtained using optimal control techniques for linear systems. The controller in question gives directly the conduction sequences of the inverter supplying the ind…
What really causes large price changes?
2003
We study the cause of large fluctuations in prices in the London Stock Exchange. This is done at the microscopic level of individual events, where an event is the placement or cancellation of an order to buy or sell. We show that price fluctuations caused by individual market orders are essentially independent of the volume of orders. Instead, large price fluctuations are driven by liquidity fluctuations, variations in the market's ability to absorb new orders. Even for the most liquid stocks there can be substantial gaps in the order book, corresponding to a block of adjacent price levels containing no quotes. When such a gap exists next to the best price, a new order can remove the best q…
Competitive selection in mono-, di- and tri-genotype cultures of Drosophila melanogaster
2009
Viability and larva-to-adult development of three strains of Drosophila melanogaster (one wild strain and two eye mutant strains: cardinal and sepia) were studied under three different situations: A. Monocultures of wild, cardinal and sepia respectively. B. Dicultures with the combinations wild/cardinal, wild/sepia and cardinal/sepia respectively. Seven points of different genetical composition were chosen for each of the three systems. C. Tricultures with wild/cardinal/sepia. Seventy composition points were chosen. The points arranged in a three dimensional diagram with the axes wild, cardinal and sepia, make up an equilateral triangle hyperplane. An analysis of optimal density and intrins…
The cost advantage of Sicilian wine farms
2013
This study presents the results of research carried out on a Sicilian wine farm in order to demonstrat e the economic convenience of the mechanized harvest. After the determination of the minimum optimal farm size that justifies the introduction of grape harve ster in the farm, it has been estimated production cost and the relative profitability of two wine grape cultiv ars (Chardonnay and Nero d’Avola), comparing three hypotheses of harvest: manual, with farm property g rape harvester and with rented grape harvester. The economic analysis shows that the introduction of th e grape harvester in the wine farm is justified in large sized farms. However, even in small farms the use o f rented g…
Optimal passive-damping design using a decentralized velocity-feedback H-infinity approach
2012
In this work, a new strategy to design passive energy dissipation systems for vibration control of large structures is presented. The method is based on the equivalence between passive damping systems and fully decentralized static velocity-feedback controllers. This equivalence allows to take advantage of recent developments in static output-feedback control design to formulate the passive-damping design as a single optimization problem with Linear Matrix Inequality constraints. To illustrate the application of the proposed methodology, a passive damping system is designed for the seismic protection of a five-story building with excellent results. Peer Reviewed
Food supplementation reveals constraints and adaptability of egg quality in the magpie Pica pica
2015
Differences in the deposition of limited maternal resources to eggs can reflect the optimal allocation to manipulate offspring phenotype, or constraints caused by maternal condition. We examined multiple maternal substances transferred to eggs in the magpie Pica pica to test the hypothesis that certain substances represent constraint and some optimal allocation. We did this by supplementary feeding magpies prior to egg-laying and then comparing the effect of food on maternal substances in conjunction with laying order relative to a control group. Certain substances such as carotenoids, immunoglobulins and avidin responded positively to food supplementation, whereas others, such as testoste…
Simulation of a UAV ground control station
2012
International audience; In this article we present the development of a UAV ground control station simulator. We propose a module based description of the architecture of this simulator. We recall the nonlinear model of a fixed-wing aircraft. Finally, we outline ideas for improved path planning tasks. The approach is made clearthrough several diagrams, figures of the resulting station are displayed.
Méthodes géometriques en mécanique spatiale et aspects numériques
2005
We present in this thesis two research projectson the optimal control of the space vehicles.In the first, we have dealt with the orbit transferproblem. We study the minimum time control of a satellite that we want to reach a geostationary orbit. Our contribution is of two kinds. Geometric, first, since we study the controllability of the system together with the geometry of the transfer (structure of the command) by means of geometric control without state constraint tools (minimum principle). Then we present shootingalgorithm and homotopy method. These approaches allow the numerical resolution of problems with strong or low thrust satellites.The second project concerns to the calculation o…
Continuous optimal control sensitivity analysis with AD
2000
In order to apply a parametric method to a minimum time control problem in celestial mechanics, a sensitivity analysis is performed. The analysis is continuous in the sense that it is done in the infinite dimensional control setting. The resulting sufficient second order condition is evaluated by means of automatic differentiation, while the associated sensitivity derivative is computed by continuous reverse differentiation. The numerical results are given for several examples of orbit transfer, also illustrating the advantages of automatic differentiation over finite differences for the computation of gradients on the discretized problem.