On the uniqueness of invariant tori in D4*S1 symmetric systems

The uniqueness of the branch of two-tori in the D4-equivariant Hopf bifurcation problem is proved in a neighbourhood of a particular limiting case where, after reduction, the Euler equations for the rotation of a free rigid body apply

Bifurcation of periodic orbits near a frequency maximum in near-integrable driven oscillators with friction

We investigate analytically the effect of perturbations on an integrable oscillator in one degree of freedom whose frequency shows a maximum as a function of the energy, i.e. a system with nonmonotone twist. The perturbation depends on three parameters: one parameter describes friction such that the Jacobian is constant and less than one. A second and a third describe the variation of the frequency and of the strength of the driving force respectively. The main result is the appearance of two chains of saddle node pairs in the phase portrait. This contrasts with the bifurcation of one chain of periodic orbits in the case of perturbations of monotone twist systems. This result is obtained for a mapping, but it is demonstrated that the same formalism and results apply for time continuous systems as well. In particular we derive an explicit expression for the stroboscopic mapping of a particle in a potential well, driven by a periodic force and under influence of friction, thus giving a clear physical interpretation to the bifurcation parameters in the mapping

The 41Ca(n,α)38Ar cross section up to 100 keV neutron energy

The 41Ca(n,alpha)38Ar reaction cross section has been studied with resonance neutrons at the GELINA neutron facility of the Institute for Reference Materials and Measurements in Geel (Belgium) from a few eV up to 100 keV. A Frisch-gridded ionization chamber with methane as detector gas was installed at a 30 meter long flight path. About 20 resonances have been identified. From the cross section data obtained, the Maxwellian averaged cross section (MACS) as a function of stellar temperature has been calculated by numerical integration

Hopf bifurcation with non-semisimple 1:1 resonance

A generalised Hopf bifurcation, corresponding to non-semisimple double imaginary eigenvalues (case of 1:1 resonance), is analysed using a normal form approach. This bifurcation has linear codimension-3, and a centre subspace of dimension 4. The four-dimensional normal form is reduced to a three-dimensional system, which is normal to the group orbits of a phase-shift symmetry. There may exist 0, 1 or 2 small-amplitude periodic solutions. Invariant 2-tori of quasiperiodic solutions bifurcate from these periodic solutions. The authors locate one-dimensional varieties in the parameter space 1223 on which the system has four different codimension-2 singularities: a Bogdanov-Takens bifurcation a 1322 symmetric cusp, a Hopf/Hopf mode interaction without strong resonance, and a steady-state/Hopf mode interaction with eigenvalues (0, i,-i)

Complexity in decision-making - the case of Maasvlakte - Connecting decisions, arenas and actors in spatial decision-making

Decision-making about infrastructure is very complex. Decisions to develop the Rotterdam harbour are being taken in a network of local, regional and national actors and influenced by international actors (firms, NGO’s etc.) both public and private. This decision-making process shows a lot of uncertainty and complexity and the outcomes are of great importance for the development of the harbour. Network theory has been widely used to indicate, explain and manage uncertainty in decision-making processes. The theory is well equipped for empirical research and has shown many applicable results. The attention for influences from outside the network to decision-making inside the network is however still poorly developed. In the case of decision-making with a strong international component this is a handicap. In this paper the relation between influences from outside and decision-making inside networks is studied both theoretically and empirically. A distinction is made between locally bound and non-locally bound networks to theorise the complex decision-making process. The well-known scientific concept of space of flows versus space of places from Manuel Castells is used as an inspiration to describe the relation between the locally and non-locally bounded networks of decision making. The locally bounded network is formed by the formal decision making process between the governmental and non-governmental organisations in countries, regions and municipalities. The non-locally bounded networks exist of organizations that are footloose and act globally mainly according to economic principals. The concept of inclusion is used to analyse the various actors in the decision-making process. The paper starts with the description of the external influences in port areas in general. The balance between the influence of local and non-local bounded networks depends on the multiple-inclusion of the different actors in the decision-making process in both networks. In areas in which many actors are included in the place-bounded networks, the external influences can be expected to be marginal. The port area of Rotterdam is a node in international networks and so the hypothesis can be set that in the Rotterdam port area the influence of actors mainly included in non-place bounded networks is significant in decision making networks. To explore this assumption various networks, which are relevant for decision-making about spatial issues in the Rotterdam port are identified and the differences in inclusion of the relevant actors is analysed. By means of the analysis of perceptions of the various actors (locally bound or non-locally bound) and their strategic choices and decisions we show that notions on international port development are being interpreted and transformed quite differently by the various actors. This first part of analysis highlights the possible gap between the awareness of the various actors of the non-locally bounded networks and their translation into their strategies in local bounded networks. We also trace difference of perceptions and strategies between actors who solely operate in locally bound networks and actors who are both included in locally and non-locally bound networks (like shipping firms etc). This second part of analysis indicates if there are differences in what the actors use as input for their respective positions in the decision-making networks. The paper shows that the influence of external developments in non-locally bound networks manifests itself in locally bound networks but is transformed and interpreted in many ways by the different actors. The paper ends with some conclusions about decision-making on large ports and the possibilities to influence this complex decision-making process that takes place in locally bound and non-locally bounded networks at the same time.

On phase-locking of oscillators with delay coupling

We consider two oscillators with delayed direct and velocity coupling. The oscillators have frequencies close or equal to 1:1 resonance. Due to the coupling the oscillations of the subsystems are in or out of phase. For these synchronized and anti-phase solutions, we use averaging for analytical stability results for small parameters. We also determine bifurcation curves of the delay system numerically. We identify regions in the parameter space (two coupling constants and the delay) where both solutions are stable or only one. For small parameters the averaging and numerical results are in good agreement. For larger values of the delay, we find multiple synchronized and anti-phase solutions. For small detuning we show that a minimal coupling value is needed to have almost synchronous or anti-phase behaviour

Crafting Firm Competencies to Improve Innovative Performance.

Recent interdisciplinary research suggests that customer and technological competencies have a direct, unconditional effect on firms' innovative performance. This study extends this stream of literature by considering the effect of organizational competencies. Results from a survey-research executed in the fast moving consumer goods industry suggest that firms that craft organizational competencies - such as improving team cohesiveness and providing slack time to foster creativity - do not directly improve their innovative performance. However, those firms that successfully combine customer, technological and organizational competencies will create more innovations that are new to the market.Innovation, Research and Development, Consumer Goods, Product Innovation, Production Management, Personnel Management, Capability Building