Search results for " Opera"

Stability and -Gain Control of Positive Switched Systems with Time-Varying Delays via Delta Operator Approach

2013

This paper investigates the problems of stability and -gain controller design for positive switched systems with time-varying delays via delta operator approach. The purpose is to design a switching signal and a state feedback controller such that the resulting closed-loop system is exponentially stable with -gain performance. Based on the average dwell time approach, a sufficient condition for the existence of an -gain controller for the considered system is established by constructing an appropriate copositive type Lyapunov-Krasovskii functional in delta domain. Moreover, the obtained conditions can unify some previously suggested relevant methods in the literature of both continuous- and…

Quantized Dissensus in Networks of Agents subject to Death and Duplication

2012

Dissensus is a modeling framework for networks of dynamic agents in competition for scarce resources. Originally inspired by biological cells behaviors, it fits also marketing, finance and many other application areas. Competition is often unstable in the sense that strong agents, those having access to large resources, gain more and more resources at the expense of weak agents. Thus, strong agents duplicate when reaching a critical amount of resources, whereas weak agents die when loosing all their resources. To capture all these phenomena we introduce systems with a discrete time gossip and unstable state dynamics interrupted by discrete events affecting the network topology. Invariancy o…

A Branch-and-Cut method for the Capacitated Location-Routing Problem

2011

International audience; Recent researches in the design of logistic networks have shown that the overall distribution cost may be excessive if routing decisions are ignored when locating depots. The Location-Routing Problem (LRP) overcomes this drawback by simultaneously tackling location and routing decisions. The aim of this paper is to propose an exact approach based on a Branch-and-Cut algorithm for solving the LRP with capacity constraints on depots and vehicles. The proposed method is based on a zero-one linear model strengthened by new families of valid inequalities. The computational evaluation on three sets of instances (34 instances in total), with 5–10 potential depots and 20–88 …

Swing options in commodity markets: a multidimensional Lévy diffusion model

2013

Author's version of an article in the journal: Mathematical Methods of Operations Research. Also available from the publisher at: http://dx.doi.org/10.1007/s00186-013-0452-7 We study valuation of swing options on commodity markets when the commodity prices are driven by multiple factors. The factors are modeled as diffusion processes driven by a multidimensional Lévy process. We set up a valuation model in terms of a dynamic programming problem where the option can be exercised continuously in time. Here, the number of swing rights is given by a total volume constraint. We analyze some general properties of the model and study the solution by analyzing the associated HJB-equation. Furthermo…

A computational study of LP-based heuristic algorithms for two-dimensional guillotine cutting stock problems

2002

In this paper we develop and compare several heuristic methods for solving the general two-dimensional cutting stock problem. We follow the Gilmore-Gomory column generation scheme in which at each iteration a new cutting pattern is obtained as the solution of a subproblem on one stock sheet. For solving this subproblem, in addition to classical dynamic programming, we have developed three heuristic procedures of increasing complexity, based on GRASP and Tabu Search techniques, producing solutions differing in quality and in time requirements. In order to obtain integer solutions from the fractional solutions of the Gilmore-Gomory process, we compare three rounding procedures, rounding up, t…

Comprensión de textos expositivos académicos en e-book Reader y en papel: influencia del conocimiento previo de dominio y la aptitud verbal

2018

espanolResumen: En un estudio del que participaron 102 estudiantes universitarios, se comparo la comprension en la lectura de textos expositivos academicos impresos versus en formato de e-book Reader. Se examinaron los efectos del soporte, del conocimiento especifico de dominio previo del lector y la aptitud verbal. Asimismo se indagaron las actitudes de los estudiantes hacia los soportes textuales antes y despues de la experiencia. Los resultados sugieren que el e-book Reader beneficiaria a los lectores competentes, y/o que podria promover mayor actividad metacognitiva en los procesos de comprension. Asimismo, las opiniones hacia el e-book Reader cambiaron despues de la experiencia, aunque…

EMISSION FACTORS, VEHICLE MODAL ACTIVITY AND ROAD OPERATIONS. A MESOSCOPIC APPROACH

2009

Current studies underline that vehicle emissions are highly linked to modal vehicle activity and a modal approach to traffic-related air quality modeling is suitable to estimate mobile source contribution to air quality. Pollutant emissions depend on characteristics of vehicles in traffic flow and on road operating conditions predictable after the implementation of the road project; then, the usual emission rate models do not predict properly the on-road vehicles emissions of modal traffic events, such as those ones occurring at intersections. Moreover modal activity analysis carried out at micro scale level, as required by modal emission models, will be still necessary to value reliable em…

Pathway network inference from gene expression data

2014

[EN] Background: The development of high-throughput omics technologies enabled genome-wide measurements of the activity of cellular elements and provides the analytical resources for the progress of the Systems Biology discipline. Analysis and interpretation of gene expression data has evolved from the gene to the pathway and interaction level, i.e. from the detection of differentially expressed genes, to the establishment of gene interaction networks and the identification of enriched functional categories. Still, the understanding of biological systems requires a further level of analysis that addresses the characterization of the interaction between functional modules. Results: We presen…

Determinazione tramite GC/MS di etilentiourea (ETU) in urine di lavoratori di una azienda vitivinicola siciliana esposti a mancozeb

2008

Do You See What I See? Effectiveness of 360-Degree vs. 2D Video Ads Using a Neuroscience Approach

2021

[EN] This study compares cognitive and emotional responses to 360-degree vs. static (2D) videos in terms of visual attention, brand recognition, engagement of the prefrontal cortex, and emotions. Hypotheses are proposed based on the interactivity literature, cognitive overload, advertising response model and motivation, opportunity, and ability theoretical frameworks, and tested using neurophysiological tools: electroencephalography, eye-tracking, electrodermal activity, and facial coding. The results revealed that gaze view depends on ad content, visual attention paid being lower in 360-degree FMCG ads than in 2D ads. Brand logo recognition is lower in 360-degree ads than in 2D video ads. …