Global Stability (global + stability)

Distribution by Scientific Domains


Selected Abstracts


MARKET SELECTION OF FINANCIAL TRADING STRATEGIES: GLOBAL STABILITY

MATHEMATICAL FINANCE, Issue 4 2002
Igor V. Evstigneev
In this paper we analyze the long-run dynamics of the market selection process among simple trading strategies in an incomplete asset market with endogenous prices. We identify a unique surviving financial trading strategy. Investors following this strategy asymptotically gather total market wealth. This result generalizes findings by Blume and Easlcy (1992) to any complete or incomplete asset market. [source]


Global stability results for systems under sampled-data control

INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 10 2009
Iasson Karafyllis
Abstract In this work sufficient conditions for uniform input-to-output stability and uniform input-to-state stability are presented for finite-dimensional systems under feedback control with zero-order hold. The conditions are expressed by means of single and vector Lyapunov functions. Copyright © 2008 John Wiley & Sons, Ltd. [source]


Global stability and the Hopf bifurcation for some class of delay differential equation

MATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 10 2008
Marek Bodnar
Abstract In this paper, we present an analysis for the class of delay differential equations with one discrete delay and the right-hand side depending only on the past. We extend the results from paper by U. Fory, (Appl. Math. Lett. 2004; 17(5):581,584), where the right-hand side is a unimodal function. In the performed analysis, we state more general conditions for global stability of the positive steady state and propose some conditions for the stable Hopf bifurcation occurring when this steady state looses stability. We illustrate the analysis by biological examples coming from the population dynamics. Copyright © 2007 John Wiley & Sons, Ltd. [source]


Climate change affects colonization dynamics in a metacommunity of three Daphnia species

GLOBAL CHANGE BIOLOGY, Issue 6 2008
FLORIAN ALTERMATT
Abstract Climate change is expected to alter the range and abundance of many species by influencing habitat qualities. For species living in fragmented populations, not only the quality of the present patches but also access to new habitat patches may be affected. Here, we show that colonization in a metacommunity can be directly influenced by weather changes, and that these observed weather changes are consistent with global climate change models. Using a long-term dataset from a rock pool metacommunity of the three species Daphnia magna, Daphnia longispina and Daphnia pulex with 507 monitored habitat patches, we correlated a four-fold increase in colonization rate with warmer, drier weather for the period from 1982 to 2006. The higher colonization rate after warm and dry summers led to an increase in metacommunity dynamics over time. A mechanistic explanation for the increased colonization rate is that the resting stages have a higher exposure to animal and wind dispersal in desiccated rock pools. Although colonization rates reacted in the same direction in all three species, there were significant species-specific effects that resulted in an overall change in the metacommunity composition. Increased local instability and colonization dynamics may even lead to higher global stability of the metacommunity. Thus, whereas climate change has been reported to cause a unidirectional change in species range for many other species, it changes the dynamics and composition of an entire community in this metacommunity, with winners and losers difficult to predict. [source]


Adaptive control of stochastic nonlinear systems with uncontrollable linearization

INTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 7 2009
Wang Qiang-de
Abstract For a class of high-order stochastic nonlinear systems with uncontrollable linearization, this paper investigates the problem of adaptive global stability in probability. By using the tool of adaptive adding a power integrator, a feedback domination design approach is presented and a smooth controller is constructed. The closed-loop stochastic system is proved to be globally stable in probability and the states can be regulated to the origin almost surely. Copyright © 2008 John Wiley & Sons, Ltd. [source]


Adaptive robust control of nonlinear systems with dynamic uncertainties

INTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 4 2009
Xiangbin Liu
Abstract In this paper, the discontinuous projection-based adaptive robust control (ARC) approach is extended to a class of nonlinear systems subjected to parametric uncertainties as well as all three types of nonlinear uncertainties,uncertainties could be state-dependent, time-dependent, and/or dynamic. Departing from the existing robust adaptive control approach, the proposed approach differentiates between dynamic uncertainties with and without known structural information. Specifically, adaptive robust observers are constructed to eliminate the effect of dynamic uncertainties with known structural information for an improved steady-state output tracking performance,asymptotic output tracking is achieved when the system is subjected to parametric uncertainties and dynamic uncertainties with known structural information only. In addition, dynamic normalization signals are introduced to construct ARC laws to deal with other uncertainties including dynamic uncertainties without known structural information not only for global stability but also for a guaranteed robust performance in general. Copyright © 2008 John Wiley & Sons, Ltd. [source]


Mixed Isobutylphobane/N-Heterocyclic Carbene Ruthenium- Indenylidene Complexes: Synthesis and Catalytic Evaluation in Olefin Metathesis Reactions

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2010
Xavier Sauvage
Abstract Two new second generation ruthenium(II) dichloride-indenylidene complexes [RuCl2(9-isobutylphosphabicyclo[3.3.1]nonane)(NHC)(3-phenyl-1-indenylidene)], where NHC=1,3-bis(2,4,6-trimethylphenyl)imidazolin-2-ylidene (SIMes) or its unsaturated imidazol-2-ylidene analogue (IMes), were isolated in high yields upon heating a tetrahydrofuran (THF) solution of the diphosphane complex [RuCl2(isobutylphobane)2(3-phenyl-1-indenylidene)] with a two-fold excess of the corresponding imidazol(in)ium-2-carboxylate zwitterions. Both products were characterized by 1H, 13C, and 31P,NMR spectroscopy, and the molecular structure of [RuCl2(isobutylphobane)(SIMes)(3-phenyl-1-indenylidene)] was determined by X-ray diffraction analysis. A close inspection of the packing structure revealed the presence of different types of intra- and intermolecular interactions that enhanced the global stability of the crystals, while low temperature NMR experiments showed the existence of two distinct rotational isomers due to the unsymmetrical nature of the phobane ligand. The catalytic activity of both compounds was assessed in olefin metathesis using benchmark ring-opening metathesis polymerization, ring-closing metathesis (RCM), and cross-metathesis reactions, and compared with those of related first and second generation ruthenium-benzylidene and indenylidene catalyst precursors. Kinetic studies confirmed the high thermal stability of the mixed isobutylphobane/N-heterocyclic carbene complexes, which suffered from a slow initiation efficiency compared to other catalytic systems based on the tricyclohexylphosphane ligand. However, the remarkable robustness of [RuCl2(isobutylphobane)(SIMes)(3-phenyl-1-indenylidene)] was beneficial for performing the RCM of diethyl 2,2-bis(2-methylallyl)malonate. Monitoring the formation of the ruthenium-methylidene active species [RuCl2(isobutylphobane)(SIMes)(CH2)] derived from this precursor further demonstrated its ability to sustain long reaction times and high temperatures required to carry out the RCM of tetrasubstituted olefins. [source]


A differential constraint approach to obtain global stability for radiation-induced double-diffusive convection in a porous medium

MATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 8 2009
Antony A. Hill
Abstract The stability of double-diffusive porous convection with a concentration-based internal heat source is studied. Owing to the significant sensitivity of standard energy method, a highly desirable reduction in the number of required coupling parameters is achieved through the novel energy method of van Duijn et al. (Environmental Mechanics: Water, Mass and Energy Transfer in the Biosphere. American Geophysical Union: Washington, DC, 2002; 155,169). This approach incorporates the Darcy equation as a differential constraint, and has been shown by van Duijn et al. to generally yield sharper nonlinear results. Owing to the widespread use of coupling parameters in analysing porous media stability, this result strongly advocates the differential constraint approach for obtaining optimal nonlinear stability thresholds. Copyright © 2008 John Wiley & Sons, Ltd. [source]


Global stability and the Hopf bifurcation for some class of delay differential equation

MATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 10 2008
Marek Bodnar
Abstract In this paper, we present an analysis for the class of delay differential equations with one discrete delay and the right-hand side depending only on the past. We extend the results from paper by U. Fory, (Appl. Math. Lett. 2004; 17(5):581,584), where the right-hand side is a unimodal function. In the performed analysis, we state more general conditions for global stability of the positive steady state and propose some conditions for the stable Hopf bifurcation occurring when this steady state looses stability. We illustrate the analysis by biological examples coming from the population dynamics. Copyright © 2007 John Wiley & Sons, Ltd. [source]


A predator,prey model with disease in the prey species only

MATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 8 2007
David Greenhalgh
Abstract A predator,prey model with transmissible disease in the prey species is proposed and analysed. The essential mathematical features are analysed with the help of equilibrium, local and global stability analyses and bifurcation theory. We find four possible equilibria. One is where the populations are extinct. Another is where the disease and predator populations are extinct and we find conditions for global stability of this. A third is where both types of prey exist but no predators. The fourth has all three types of individuals present and we find conditions for limit cycles to arise by Hopf bifurcation. Experimental data simulation and brief discussion conclude the paper. Copyright © 2006 John Wiley & Sons, Ltd. [source]


Existence, uniqueness, stochastic persistence and global stability of positive solutions of the logistic equation with random perturbation

MATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 1 2007
Chunyan Ji
Abstract This paper discusses a randomized logistic equation (1) with initial value x(0)=x0>0, where B(t) is a standard one-dimension Brownian motion, and ,,(0, 0.5). We show that the positive solution of the stochastic differential equation does not explode at any finite time under certain conditions. In addition, we study the existence, uniqueness, boundedness, stochastic persistence and global stability of the positive solution. Copyright © 2006 John Wiley & Sons, Ltd. [source]


Adaptive output feedback control for a class of planar nonlinear systems,

ASIAN JOURNAL OF CONTROL, Issue 5 2009
Fang Shang
Abstract This paper is concerned with the problem of global adaptive stabilization by output feedback for a class of planar nonlinear systems with uncertain control coefficient and unknown growth rate. The control coefficient is not supposed to have known upper bound, and this relaxes the corresponding requirement in the existing literature (see e.g. 1, 2. First, by the universal control method, an observer is constructed based on the dynamic high-gain K-filters. Then, the control design procedure is developed to obtain the stabilizing controller and dynamic compensator for the uncertainties in the control coefficient. It is shown that the global stability of the closed-loop system can be guaranteed by the appropriate choice of the design parameters. A simulation example is also provided to illustrate the correctness of the theoretical results. © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society. [source]


The Rich Tradition of Australian Realism

AUSTRALIAN JOURNAL OF POLITICS AND HISTORY, Issue 3 2009
Michael Wesley
Australian International Relations (IR) developed as a discipline at the same time as its emergence in the rest of the Anglophone world. A deep reading of Australian writing on international relations since the 1920s reveals a distinctive tradition of IR scholarship, shaped very much by this country's international circumstances and the pragmatic culture of political inquiry that pervaded its universities and diplomatic institutions. Three characteristics frame the Australian Realist outlook. The first is experiential, a preoccupation with the particularities of Australia's international position , size, isolation, wealth, population, culture , and how these factors can help understand the ways in which Australia relates to the world beyond its shores. The second is systemic pessimism, a tendency to be apprehensive about broader global stability. The third is pragmatism, a predilection for understanding the essential attributes of the situation itself, rather than using the situation to inquire into the general nature of the international system. These characteristics have fostered sustained attention to three sets of issues: geography, demographics and race, and power differentials in Australian Realist scholarship. [source]


Isofagomine Induced Stabilization of Glucocerebrosidase

CHEMBIOCHEM, Issue 16 2008
Gregory J. Kornhaber Dr.
Abstract Structurally destabilizing mutations in acid ,-glucosidase (GCase) can result in Gaucher disease (GD). The iminosugar isofagomine (IFG), a competitive inhibitor and a potential pharmacological chaperone of GCase, is currently undergoing clinical evaluation for the treatment of GD. An X-ray crystallographic study of the GCase-IFG complex revealed a hydrogen bonding network between IFG and certain active site residues. It was suggested that this network may translate into greater global stability. Here it is demonstrated that IFG does increase the global stability of wild-type GCase, shifting its melting curve by ,15,°C and that it enhances mutant GCase activity in pre-treated N370S/N370S and F213I/L444P patient fibroblasts. Additionally, amide hydrogen/deuterium exchange mass spectroscopy (H/D-Ex) was employed to identify regions within GCase that undergo stabilization upon IFG-binding. H/D-Ex data indicate that the binding of IFG not only restricts the local protein dynamics of the active site, but also propagates this effect into surrounding regions. [source]