Complex Dynamical Regimes Research Articles

Historical and future black carbon deposition on the three ice caps: Ice core measurements and model simulations from 1850 to 2100

AbstractIce core measurements in conjunction with climate model simulations are of tremendous value when examining anthropogenic and natural aerosol loads and their role in past and future climates. Refractory black carbon (BC) records from the Arctic, the Antarctic, and the Himalayas are analyzed using three transient climate simulations performed with the Goddard Institute for Space Studies ModelE. Simulations differ in aerosol schemes (bulk aerosols vs. aerosol microphysics) and ocean couplings (fully coupled vs. prescribed ocean). Regional analyses for past (1850–2005) and future (2005–2100) carbonaceous aerosol simulations focus on the Antarctic, Greenland, and the Himalayas. Measurements from locations in the Antarctic show clean conditions with no detectable trend over the past 150 years. Historical atmospheric deposition of BC and sulfur in Greenland shows strong trends and is primarily influenced by emissions from early twentieth century agricultural and domestic practices. Models fail to reproduce observations of a sharp eightfold BC increase in Greenland at the beginning of the twentieth century that could be due to the only threefold increase in the North American emission inventory. BC deposition in Greenland is about 10 times greater than in Antarctica and 10 times less than in Tibet. The Himalayas show the most complicated transport patterns, due to the complex terrain and dynamical regimes of this region. Projections of future climate based on the four CMIP5 Representative Concentration Pathways indicate further dramatic advances of pollution to the Tibetan Plateau along with decreasing BC deposition fluxes in Greenland and the Antarctic.

Constitutionalization by Association? The Doubtful Case of the European Economic Area

The European Economic Area (EEA) is a special form of association created initially for all the European Free Trade Area (EFTA) countries which were looking for a way to strengthen their economic ties with the European Union’s (EU) single market without abandoning their sovereignty to the extent of joining the EU to become a Member State. The EEA Agreement aims to reconcile the logics of integration and of preservation of sovereignty using tools of international law to prevent on the one hand the transfer of legislative powers and sovereignty of the EFTA EEA States and to create on the other hand a complex dynamic legal regime; this legal regime encompasses the constant adaptation of EEA law to new relevant legislation adopted in the EU and the homogeneous interpretation of legal provisions identical to norms of the Treaty on the Functioning of the European Union (TFEU), referring for this latter...

Semiconductor ring laser subject to delayed optical feedback: Bifurcations and stability

We study semiconductor ring lasers subject to delayed optical feedback from one or two short external cavities. In case of two cavities we consider the feedback strengths and phases to be either symmetric or asymmetric feedback. When feedback is symmetric, the laser operates in a bi-directional continuous wave or periodic regime for most parameter values. Only for some small parameter regions complex dynamics, such as quasi-periodicity and chaos are obtained. When the feedback is asymmetric complex dynamical regimes, including chaos, are obtained in large parameter regions. We explain complex dynamical regimes obtained in both symmetric and asymmetric feedback cases by linear stability of the stationary solutions calculated using DDE-BIFTOOL.

Topological structures enhance the presence of dynamical regimes in synthetic networks

Genetic and protein networks, through their underlying dynamical behavior, characterize structural and functional cellular processes, and are thus regarded as "driving forces" of all living systems. Understanding the rhythm generation mechanisms that emerge from such complex networks has benefited in recent years by synthetic approaches, through which simpler network modules (e.g., switches and oscillators) have been built. In this manner, a significant attention to date has been focused on the dynamical behavior of these isolated synthetic circuits, and the occurrence of unifying rhythms in systems of globally coupled genetic units. In contrast to this, we address here the question: Could topologically distinct structures enhance the presence of various dynamical regimes in synthetic networks? We show that an intercellular mechanism, engineered to operate on a local scale, will inevitably lead to multirhythmicity, and to the appearance of several coexisting (complex) dynamical regimes, if certain preconditions regarding the dynamical structure of the synthetic circuits are met. Moreover, we discuss the importance of regime enhancement in synthetic structures in terms of memory storage and computation capabilities.

Identifying the dynamics of complex spatio-temporal systems by spatial recurrence properties

Complex spatio-temporal systems may exhibit irregular behaviors when driven far from equilibrium. Reaction-diffusion systems often lead to the formation of patterns and spatio-temporal chaos. When a limited number of observations is available, the reconstruction and identification of complex dynamical regimes become challenging problems. A method based on spatial recurrence properties is proposed to deal with this problem: generalized recurrence plots and generalized recurrence quantification analysis are exploited to show that detection of structural changes in spatially distributed systems can be performed by setting up appropriate diagrams accounting for different spatial recurrences. The method has been tested on two prototypical systems forming complex patterns: the complex Ginzburg-Landau equation and the Schnakenberg system. This work allowed us to identify changes in the stability of spiral wave solutions in the former system and to analyze the Turing bifurcations in the latter.

Diffusion-induced instability and chaos in random oscillator networks

We demonstrate that diffusively coupled limit-cycle oscillators on random networks can exhibit various complex dynamical patterns. Reducing the system to a network analog of the complex Ginzburg-Landau equation, we argue that uniform oscillations can be linearly unstable with respect to spontaneous phase modulations due to diffusional coupling-the effect corresponding to the Benjamin-Feir instability in continuous media. Numerical investigations under this instability in random scale-free networks reveal a wealth of complex dynamical regimes, including partial amplitude death, clustering, and chaos. A dynamic mean-field theory explaining different kinds of nonlinear dynamics is constructed.

Complexity measures from interaction structures

We evaluate information-theoretic quantities that quantify complexity in terms of kth-order statistical dependences that cannot be reduced to interactions among k-1 random variables. Using symbolic dynamics of coupled maps and cellular automata as model systems, we demonstrate that these measures are able to identify complex dynamical regimes.

Optimal reconfiguration maneuvers for spacecraft imaging arrays in multi-body regimes

Upcoming National Aeronautics and Space Administration (NASA) mission concepts include satellite arrays to facilitate imaging and identification of distant planets. These mission scenarios are diverse, including designs such as the terrestrial planet finder-occulter (TPF-O), where a monolithic telescope is aided by a single occulter spacecraft, and the micro-arcsecond X-ray imaging mission (MAXIM), where as many as 16 spacecraft move together to form a space interferometer. Each design, however, requires precise reconfiguration and star tracking in potentially complex dynamic regimes. This paper explores control methods for satellite imaging array reconfiguration in multi-body systems. Specifically, optimal nonlinear control and geometric control methods are derived and compared to the more traditional linear quadratic regulators, as well as input state feedback linearization. These control strategies are implemented and evaluated for the TPF-O mission concept.

Electrohydrodynamics of yeast cells in microchannels subjected to travelling electric fields

While travelling wave dielectrophoresis (twDEP) offers a promising method for the control of micro-sized particles suspended in liquids, particularly when the motion of particles along the length of the channel is sought without having to pump the liquid itself, it leads to a variety of complex dynamical regimes which need to be clearly understood for the design of efficient microfluidic devices targeting particular functions. In this paper, we describe the various dynamical regimes in terms of the forces acting on the particles, i.e. the conventional dielectrophoretic and twDEP force and torque, the viscous drag exerted by the fluid on the particle and the electrostatic and hydrodynamic particle–particle interactions. We also explore the variation of the dynamical regimes in three different configurations typical of microfluidic channels whose electrodes are embedded in the bottom wall. The first two configurations have different, i.e. aligned and staggered, electrode geometries, and the third configuration consists of aligned electrodes but energized at different potentials. For these purposes, we use our direct numerical simulation code based on the distributed Lagrange multiplier method for solving the equations of motion for both the fluid and the individual particles, and the point dipole model to compute the electrostatic forces. The model particles are chosen so as to have mechanical and electrical properties of yeast cells suspended in an aqueous solution. It is found that the motion of the particles not only depends significantly on the Clausius–Mossotti factor, which is a function of the electric properties of the fluid and the particles, but also on the specific configuration considered. Particularly, the spinning of particles plays a crucial role in the particle translations and interactions, but the direction of such spinning motion depends on the particular device configuration used.

Transient activation in a network of coupled map neurons.

The focus of this Letter is on the activity of a network of neurons pairwise coupled by inhibitory connections. Each neuron is represented by a two-dimensional map capable, when isolated, of a rich variety of complex dynamical regimes. It is shown that the network exhibits a stimulus-dependent sequential activation and inactivation of subgroups of neurons. This complex behavior is rather similar to some spatiotemporal features observed in the first stages of the olfaction process in some insects and suggests the possibility of large scale simulation of these processes by using reasonable computational capabilities.

Complex dynamics of a distributed parametric oscillator

The dynamics of a system with three parametrically coupled waves with delayed feedback is considered. Results of the detailed numerical simulation of the onset of self-modulation, as well as complex dynamic and chaotic regimes, are presented. The relation of self-modulation regimes with the formation and propagation of solitons is investigated. It is discovered that as the pump parameter increases, the synchronization of phases of the interacting waves, which is characteristic of stationary generation and periodic self-modulation regimes, is violated, and the system goes to a chaotic regime via intermittency.

Electrochemistry in Self-Organized Dynamical States: Current Oscillations and Potential Patterns in Electrocatalytic Reactions

Self-organized spatiotemporal periodicities of chemical origin are prominent features of all living systems. Although to date no one has ever provided a clear reason as to why biochemical systems generally prefer operating in periodic or even more complex dynamical regimes, there is agreement that non-stationary regimes far from equilibrium could offer significant evolutionary advantages to regulatory chemical mechanisms when it comes to robustness and flexibility to external perturbations. Intrigued by the idea of unraveling the mechanisms of spatiotemporal dynamics in nature, researchers have been looking for simpler chemical model systems where certain dynamic aspects could be studied in more detail.

Dynamic simulation of dynamic eccentricity in induction machines-winding function approach

The paper describes a method for the dynamic simulation of dynamic rotor eccentricity in squirrel cage rotor induction machines. The method is based on a winding function approach, which allows for all harmonics of magnetomotive force to be taken into account. It is demonstrated how this complex dynamic regime can be modeled using the mutual inductance curves of symmetrical machine using proper scaling techniques. Experimental results demonstrate the effectiveness of the proposed technique and validate the theoretical analysis.

Competition, collusion, and chaos

In this paper, we present results which show that cartel formation can still be observed in a completely deterministic model where myopic firms compete through price in finite time. The firms are spatially differentiated and take turns with their neighboring firms in setting prices. Among the different possible dynamic scenarios, we focus attention on those where cooperative and competitive behavior continue to coexist throughout time. The continual interaction of cooperative and competitive behavior results in complex dynamic regimes. Because the set of prices which firms choose will be discrete, a formal equivalence is established between the model's dynamics and the theory of cellular automata.

Neutron and raman scattering study of the soft mode behaviour at the structural phase transition in A-tCNB

Abstract Direct observations of the soft mode in A-TCNB by inelastic neutron scattering in association with Raman scattering are presented. These measurements indicate a complex dynamic regime which seems to be intermediate between displacive and order-disorder types.

Dynamics of lumped chemically reacting systems near singular bifurcation points

The systematic method of locating and classifying complex dynamical regimes of lumped reactors involves analysis of dynamics near singular bifurcation points at multiple eigenvalues. Amplitude expansion in the proximity of a singular bifurcation combined with multiple time scaling are used to derive universal equations that, though valid quantitatively only in a narrow patch of the parametric space, give full qualitative information on dynamics of a system possessing the respective highest singularity. The principal general result is that an algebraic singularity of a certain order is required to obtain dynamics of a certain dimensionality. In the lowest order, this is cusp singularity for two-dimensional dynamics in the proximity of bifurcation at double zero eigenvalue, and swallowtail singularity for three-dimensional dynamics at triple zero eigenvalue. The basic equation of two-dimensional dynamics describes various transitions between stationary and periodic states as observed, for example, in a first-order exothermic reaction. The equation of three-dimensional dynamics generates more complex phenomena, in particular, chaotic regimes.

Thermal diffusion separation of gas mixtures with the aid of laser radiation

An analysis is made of thermal diffusion processes in gas mixtures stimulated by laser radiation. It is shown that these processes may be characterized by high values of the separation coefficient. Complex dynamic regimes of thermal diffusion in a laser radiation field are revealed by the calculations. The results of an experimental study are also given.