1,859,817 research outputs found
Conceptualising Cluster Evolution: Beyond the Life-Cycle Model?
Although the literature on the evolution of industrial clusters is not vast, a preferred approach has already become evident, based around the idea of a cluster 'life-cycle'. This approach has several limitations. In this paper we explore a different conception of cluster evolution drawing on the 'adaptive cycle' model that has been developed in evolutionary ecology. Using this model, cluster evolution is viewed as an adaptive process with different possible outcomes based on episodic interactions of nested systems. Though not without limitations, this approach offers greater scope as a framework for shaping the research agenda into the evolution of clusters.Clusters, Evolution, Life-cycle model, Complex systems, Adaptive cycle model
Damage spreading and dynamic stability of kinetic Ising models
We investigate how the time evolution of different kinetic Ising models
depends on the initial conditions of the dynamics. To this end we consider the
simultaneous evolution of two identical systems subjected to the same thermal
noise. We derive a master equation for the time evolution of a joint
probability distribution of the two systems. This equation is then solved
within an effective-field approach. By analyzing the fixed points of the master
equation and their stability we identify regular and chaotic phases.Comment: 4 pages RevTeX, 2 Postscript figure
Managing evolution and change in web-based teaching and learning environments
The state of the art in information technology and educational technologies is evolving constantly.
Courses taught are subject to constant change from organisational and subject-specific reasons. Evolution
and change affect educators and developers of computer-based teaching and learning environments alike â
both often being unprepared to respond effectively. A large number of educational systems are designed
and developed without change and evolution in mind. We will present our approach to the design and
maintenance of these systems in rapidly evolving environments and illustrate the consequences of evolution
and change for these systems and for the educators and developers responsible for their implementation and
deployment. We discuss various factors of change, illustrated by a Web-based virtual course, with the
objective of raising an awareness of this issue of evolution and change in computer-supported teaching and
learning environments. This discussion leads towards the establishment of a development and management
framework for teaching and learning systems
Self-similar approach to market analysis
A novel approach to analyzing time series generated by complex systems, such
as markets, is presented. The basic idea of the approach is the {\it Law of
Self-Similar Evolution}, according to which any complex system develops
self-similarly. There always exist some internal laws governing the evolution
of a system, say of a market, so that each of such systems possesses its own
character regulating its behaviour. The problem is how to discover these hidden
internal laws defining the system character. This problem can be solved by
employing the {\it Self-Similar Approximation Theory}, which supplies the
mathematical foundation for the Law of Self-Similar Evolution. In this report,
the theoretical basis of the new approach to analyzing time series is
formulated, with an accurate explanation of its principal points.Comment: Latex file, 17 pages, no figure
Algebraic Structure of Discrete Zero Curvature Equations and Master Symmetries of Discrete Evolution Equations
An algebraic structure related to discrete zero curvature equations is
established. It is used to give an approach for generating master symmetries of
first degree for systems of discrete evolution equations and an answer to why
there exist such master symmetries. The key of the theory is to generate
nonisospectral flows from the discrete spectral
problem associated with a given system of discrete evolution equations. Three
examples are given.Comment: 24 pages, LaTex, revise
An Emergent Economics of Ecosystem Management
Economics is an evolving and emerging field of study, so is the management of ecosystems. As such, this paper delineates the co-evolution of economic evaluation that reflects the various recognized ecosystem management approaches of anticipative, adaptive and capacitive ecosystem management. Each management approach is critiqued and from this theoretical analysis an emergent approach for the management of ecosystem is put forward, which accordingly suggests an alternative methodological approach for economic evaluations.Complexity, creativity, economic evaluation, ecosystem management, evolution, open systems, rationality, Resource /Energy Economics and Policy,
Stability radius and internal versus external stability in Banach spaces: an evolution semigroup approach
In this paper the theory of evolution semigroups is developed and used to
provide a framework to study the stability of general linear control systems.
These include time-varying systems modeled with unbounded state-space operators
acting on Banach spaces. This approach allows one to apply the classical theory
of strongly continuous semigroups to time-varying systems. In particular, the
complex stability radius may be expressed explicitly in terms of the generator
of a (evolution) semigroup. Examples are given to show that classical formulas
for the stability radius of an autonomous Hilbert-space system fail in more
general settings. Upper and lower bounds on the stability radius are provided
for these general systems. In addition, it is shown that the theory of
evolution semigroups allows for a straightforward operator-theoretic analysis
of internal stability as determined by classical frequency-domain and
input-output operators, even for nonautonomous Banach-space systemsComment: Also at http://www.math.missouri.edu/~stephen/preprint
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