Stability of periodic optical solitons for a nonlinear Schrodinger system

This paper is concerned with the existence and nonlinear stability of periodic travelling-wave solutions for a nonlinear Schrodinger-type system arising in nonlinear optics. We show the existence of smooth curves of periodic solutions depending on the dnoidal-type functions. We prove stability results by perturbations having the same minimal wavelength, and instability behaviour by perturbations of two or more times the minima period. We also establish global well posedness for our system by using Bourgain`s approach.

Mean motion resonances and the stability of a circumbinary disk in a triple stellar system

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

LOSS of EXPONENTIAL STABILITY FOR A THERMOELASTIC SYSTEM WITH MEMORY

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Using transient and steady state considerations to investigate the mechanism of loss of stability of a dynamical system

This work presents the complete set of features for solutions of a particular non-ideal mechanical system near the fundamental and near to a secondary resonance region. The system comprises a pendulum with a horizontally moving suspension point. Its motion is the result of a non-ideal rotating power source (limited power supply), acting oil the Suspension point through a crank mechanism. Main emphasis is given to the loss of stability, which occurs by a sequence of events, including intermittence and crisis, when the system reaches a chaotic attractor. The system also undergoes a boundary-crisis, which presents a different aspect in the bifurcation diagram due to the non-ideal supposition. (c) 2004 Published by Elsevier B.V.

Stability regions around the components of the triple system 2001 SN263

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Stability of nonlinear system using takagi-sugeno fuzzy models and hyper-rectangle of LMIs

This paper presents a theorem based on the hyper-rectangle defined by the closed set of the time derivatives of the membership functions of Takagi-Sugeno fuzzy systems. This result is also based on Linear Matrix Inequalities and allows the reduction of the conservatism of the stability analysis in the sense of Lyapunov. The theorem generalizes previous results available in the literature. © 2013 Brazilian Society for Automatics - SBA.

Singular value analyses of voltage stability on power system considering wind generation variability

Pós-graduação em Engenharia Elétrica - FEIS

Obese elderly women exhibit low postural stability: a novel three-dimensional evaluation system

OBJECTIVE: The aim of this study was to evaluate the multisegmental static postural balance of active eutrophic and obese elderly women using a three-dimensional system under different sensory conditions. METHODS: A cross-sectional study was conducted on 31 elderly women (16 eutrophic and 15 obese) aged 65 to 75 years. The following anthropometric measurements were obtained: weight, height, waist and hip circumference, and handgrip strength. The physical activity level was evaluated using the International Physical Activity Questionnaire. Body composition was measured using the deuterium oxide dilution technique. The Polhemus (R) Patriot (three-dimensional) equipment was used to measure the parameters of postural balance along the anteroposterior and laterolateral axes. The data acquisition involved one trial of 60 s to test the limit of stability and four trials of 90 s each under the following conditions: (1) eyes open, stable surface; (2) eyes closed, stable surface; (3) eyes open, unstable surface; and (4) eyes closed, unstable surface. RESULTS: For the limit of stability, significant differences were observed in the maximum anteroposterior and laterolateral displacement (p<0.01) and in the parameter maximum anteroposterior displacement in the eyes closed stable surface condition (p<0.01) and maximum anteroposterior and laterolateral displacement in the eyes open unstable surface (p<0.01 and p = 0.03) and eyes closed unstable surface (p<0.01 and p<0.01) conditions. CONCLUSIONS: Obese elderly women exhibited a lower stability limit (lower sway area) compared with eutrophic women, leaving them more vulnerable to falls.

Synthesis in millireactor system and stability of intermediates for the functionalization of imidazole

This Master thesis presents the results obtained in the curricular traineeship, carried out within the laboratories of the Department of Chemistry of the University of Bergen, during the Erasmus period, and within the Department of Industrial Chemistry of the University of Bologna. The project followed in Bergen concerned the synthesis of key intermediates used for the functionalization of the backbone of imidazole, using N,N'- diiodo-5,5-dimethylhydantoin (“DIH”) as an iodinating agent, and employing an innovative kind of chemical reactor: the “Multijet Oscillating Disc Millireactor” (MJOD Reactor). Afterwards, the work performed in Bologna consisted in verifying the stability in solution of the above mentioned N,N'-diiodo-5,5-dimethylhydantoin utilising spectrophotometric techniques and High Performance Liquid Chromatography analyses (HPLC).

Stability analysis of a mono inverter dual sensorless motors system

When a single brush-less dc motor is fed by an inverter with a sensor-less algorithm embedded in the switching controller, the system exhibits a linear and stable output in terms of the speed and torque. However, with two motors modulated by the same inverter, the system is unstable and rendered useless for a steady application, unless provided with some resistive damping on the supply lines. The project discusses and analysis the stability of such a system through simulations and hardware demonstrations and also will discuss a method to derive the values of these damping.

Simplified small-signal stability analysis for optimized power system architecture

The optimization of power architectures is a complex problem due to the plethora of different ways to connect various system components. This issue has been addressed by developing a methodology to design and optimize power architectures in terms of the most fundamental system features: size, cost and efficiency. The process assumes various simplifications regarding the utilized DC/DC converter models in order to prevent the simulation time to become excessive and, therefore, stability is not considered. The objective of this paper is to present a simplified method to analyze small-signal stability of a system in order to integrate it into the optimization methodology. A black-box modeling approach, applicable to commercial converters with unknown topology and components, is based on frequency response measurements enabling the system small-signal stability assessment. The applicability of passivity-based stability criterion is assessed. The stability margins are stated utilizing a concept of maximum peak criteria derived from the behavior of the impedance-based sensitivity function that provides a single number to state the robustness of the stability of a well-defined minor-loop gain.

Stability Analysis of Teleoperation System by State Convergence with Variable Time Delay

We propose a novel control scheme for bilateral teleoperation of n degree-of-freedom (DOF) nonlinear robotic systems with time-varying communication delay. A major contribution from this work lies in the demonstration that the structure of a state convergence algorithm can be also applied to nth-order nonlinear teleoperation systems. By choosing a Lyapunov Krasovskii functional, we show that the local-remote teleoperation system is asymptotically stable. The time delay of communication channel is assumed to be unknown and randomly time varying, but the upper bounds of the delay interval and the derivative of the delay are assumed to be known.

Direct measurement of salt-bridge solvation energies using a peptide model system: implications for protein stability.

The solvation energies of salt bridges formed between the terminal carboxyl of the host pentapeptide AcWL- X-LL and the side chains of Arg or Lys in the guest (X) position have been measured. The energies were derived from octanol-to-buffer transfer free energies determined between pH 1 and pH 9. 13C NMR measurements show that the salt bridges form in the octanol phase, but not in the buffer phase, when the side chains and the terminal carboxyl group are charged. The free energy of salt-bridge formation in octanol is approximately -4 kcal/mol (1 cal = 4.184 J), which is equal to or slightly larger than the sum of the solvation energies of noninteracting pairs of charged side chains. This is about one-half the free energy that would result from replacing a charge pair in octanol with a pair of hydrophobic residues of moderate size. Therefore, salt bridging in octanol can change the favorable aqueous solvation energy of a pair of oppositely charged residues to neutral or slightly unfavorable but cannot provide the same free energy decrease as hydrophobic residues. This is consistent with recent computational and experimental studies of protein stability.

Creating Stability: National Preferences and the Origins of European Monetary System. CES Germany & Europe Working Papers, No. 00.9, December 2000

This essay compares the preferences of France, Italy, and Britain on the creation of the European Monetary System in 1978-1979, especially the Exchange Rate Mechanism, which stabilised nominal exchange rates. My claim is that the different conclusions reached by the governments (France and Italy in, Britain out) cannot be explained by economic circumstances or by interests, and I elaborate an intervening institutional variable which helps explain preferences. Deducing from spatial theory that where decisionmakers `sit' on the left-right spectrum matters to their position on the EMS, I argue that domestic constitutional power-. sharing mechanisms privilege certain actors over others in a predictable and consistent way. Where centrists were in power, the government's decision was to join. Where left or right extremists were privileged, the government's decision was negative. The article measures the centrism of the governments in place at the time, and also reviews the positions taken by the national political parties in and out of government. It is intended to contribute to the growing comparativist literature on the European Union, and to the burgeoning literature on EU-member-state relations.

Stability of a system of equations describing the flow behind a shock /

"This work has been supported by the National Science Foundation under Grant G-1221"