Search

The change in the phase, from quiescence to surge, may perturb the glacier’s dynamical behavior. To understand these changes through geospatial technique, the fastest moving tidewater Monacobreen Glacier, Svalbard, was studied for the year 2016–2019. It was elucidated that the surge had initiated during 2017–2018 before it the glacier was in quiescence since 2001. Initially, the glacier radar zones, namely percolation refreeze, lower percolation, and clean ice, were identified using the multi-temporal SAR data. These zones were utilized to delineate the equilibrium line altitude, and it was found that it is continuously moving down during surging, unlike the quiescence phase. The accumulation area ratio was always more than 0.67 throughout the analysis. The seasonal change in glacier surface velocity for both the phases was estimated, adapting the most appropriate Offset Tracking approach using the SAR data. The mean velocity over the main trunk was found to vary from 0.5 to 4 m/day. Thereafter, Glen's flow law equation was used to estimate the ice-thickness and found that the glacier has an average thickness range of 216–326 m in quiescence and 136–244 m during the surging. The analysis depicted that the basal shear stresses are increasing with surging, and the viscosity is decreasing. It can be said that the transition of the glacier from quiescent to surging phase has entirely changed its dynamic behavior and characteristics. Further, in the absence of field observations, the geospatial technique may provide reasonable estimates of the glacier’s physical and dynamical parameters.

Although Mn-Ga alloys are discussed as novel permanent magnetic materials, there are several drawbacks, including the high price of Ga and the yet too small saturation magnetization to name a few. We used several guidelines to motivate the replacement of Ga by Sn to tackle these issues and explored the phase formation, structural and magnetic properties of a Mn 2.6 Ga 1− x Sn x alloy series. The structure of Sn-rich samples is dominated by the corresponding hexagonal and orthorhombic phases, while the structure of Ga-rich samples shows additional contributions from the tetragonal DO 22 structure. However, formation of the tetragonal phase happens only upon an appropriate annealing procedure. In contrast to the discussion in the literature, our experiments do not hint on the tetragonal DO 22 structure being metastable, but rather indicate the DO 22 structure being an equilibrium phase. In general, the experimentally found phase fractions impact on the magnetic properties and hard magnetic properties are downgraded very rapidly even if only a small amount of Ga is substituted by Sn. This indicates that the DO 22 phase found only in the Ga-rich samples is indeed the one which is most relevant for realization of high magnetic anisotropy.

Aneurysmal subarachnoid haemorrhage (SAH) is a devastating subset of stroke. One of the major determinates of morbidity is the development of delayed cerebral ischemia (DCI). Disruption of the nitric oxide (NO) pathway and consequently the control of cerebral blood flow (CBF), known as cerebral autoregulation, is believed to play a role in its pathophysiology. Through the pharmacological manipulation of in vivo NO levels using an exogenous NO donor we sought to explore this relationship.Phase synchronisation index (PSI), an expression of the interdependence between CBF and arterial blood pressure (ABP) and thus cerebral autoregulation, was calculated before and during sodium nitrite administration in 10 high-grade SAH patients acutely postrupture. In patients that did not develop DCI, there was a significant increase in PSI around 0.1 Hz during the administration of sodium nitrite (33%; p-value 0.006). In patients that developed DCI, PSI did not change significantly.Synchronisation between ABP and CBF at 0.1 Hz has been proposed as a mechanism by which organ perfusion is maintained, during periods of physiological stress. These findings suggest that functional NO depletion plays a role in impaired cerebral autoregulation following SAH, but the development of DCI may have a distinct pathophysiological aetiology.

Chemical dynamics simulations are performed to study the dissociation of excited benzene-hexafluorobenzene (Bz-HFB) complex in N2 bath and the results are compared with the gas phase dynamics. Two N2 bath densities 20 and 750 kg/m3 are considered. Bz-HFB is excited with respect to the temperatures of 1000, 1500, and 2000 K at each bath density. The nature of the Bz-HFB* dissociation dynamics at the bath density of 20 kg/m3 is quite similar to gas phase one, but the same is drastically different at high bath density where energy transfer pathway dominates over dissociation and negligible direct dissociation of Bz-HFB* is reported.

We formulate a theory for the collective phase description of globally coupled noisy limit-cycle oscillators exhibiting macroscopic rhythms. Collective phase equations describing such macroscopic rhythms are derived by means of a two-step phase reduction. The collective phase sensitivity and collective phase coupling functions, which quantitatively characterize the macroscopic rhythms, are illustrated using three representative models of limit-cycle oscillators. As an important result of the theory, we demonstrate noise-induced anti-phase synchronization between macroscopic rhythms by direct numerical simulations of the three models., Comment: 19 pages, 11 figures

The liquid-phase processes occurring during fuel droplet combustion are important in deciding the behaviour of the overall combustion process, especially, for the binary fuel droplets. Hence, understanding these processes is essential for explaining the combustion of the binary fuel droplet. However, experimental investigation of such processes is not easily accomplishable due to the very short period of time available for tracking them within the finely small fuel droplet. In the present work, a high speed imaging and subsequent image processing leading to quantitative analysis of the binary fuel droplet combustion including liquid-phase dynamics are performed. Two categories of binary fuels – in which diesel is the base fuel – are prepared and utilized. The first category is biodiesel/diesel and bioethanol/diesel blends, while the second category is the water-in-diesel and diesel-in-water emulsions. Specific optical setup is developed and used for tracking droplet combustion. The resulting magnification of the droplet images is up to 30 times the real size, offering the possibility of droplet interior visualization at high imaging rates up (to 40,000 fps). With the aid of this setup, spatial and temporal tracking of nucleation, bubble formation, puffing, microexplosion, and secondary atomization during the combustion of two adjacent binary fuel droplets are performed. The burning rate constants are evaluated and found to have the same trends as the isolated droplet combustion. However, the ratio of the droplet burning rate constant of the interactive droplet combustion to that of the isolated droplet combustion is higher than unity. This is the same for the nucleation rate within the interacting fuel droplets.

Phase dynamics of disordered Josephson junction ladders (JJLs) driven by external currents which are spatially and temporally modulated is studied using a numerical simulation based on a random field XY model. This model is considered theoretically as an effective model of JJLs with structural disorder in a magnetic field. The spatiotemporal modulation of external currents causes peculiar dynamical effects of phases in the system under certain conditions, such as the directed motion of phases and the mode-locking in the absence of dc currents. We clarify the details of effects of the spatiotemporal modulation on the phase dynamics.

In this study, we investigate the role of stochastic parametric noise on the phase dynamics and the frequency characteristics of a vortex induced vibration (VIV) system, in the framework of synchronisation theory. In-phase, arbitrary-phase and anti-phase synchronisations exist during pre lock-in, lock-in and post lock-in regimes of the deterministic system, respectively. However the noise induced phase dynamics is found to be considerably different from the corresponding deterministic scenario and is largely dependent on the intensity of noise. Stochastic noise alters the conventional route to instability and is seen to induce new dynamical states such as Noise Induced Intermittency (NII) and quasi-periodicity in the structural response. It is also observed that noise triggers additional system frequencies in both structural and flow responses albeit not the same way. The birth of new dynamical states is strongly linked with these frequency characteristics of the structural and the flow oscillators. Phase can characterise the overall dynamics of coupled oscillators systematically and in the present study relative phase has been exploited in a stochastic framework in terms of both averaged and instantaneous quantities. The stochastic VIV system manifests asynchronous and synchronous phase dynamics as well as regions of phase slips during the transition boundaries of stochastic bifurcations. These are quantitatively and qualitatively monitored through phase coherence values in the desired parametric ranges.

[EN] The microstructure of rubber-modified polystyrene after thermal ageing at 90 °C and multiple extrusion was analyzed by time-domain nuclear magnetic resonance (TD-NMR) in a non-destructive manner. The transverse magnetization decay behaviour observed in TD-NMR was related to the total rubber fraction and its cross-linking density. The data reveal different mechanisms of long-term rubber degradation in high-impact polystyrene (HIPS) during thermo-oxidation and multiple processing: Multiple processing causes a slight increase in the cross-linking density of the rubber phase, without appreciably altering the total amount of rubber fraction. Thermo-oxidation is accompanied by a significant overall decrease of the rubber fraction, an increase of the cross-linking density, and a pronounced increase of the non-crosslinked fraction (chain ends and fragmented segments). The NMR results correlate well with spectroscopic observations and moderately with macroscopic mechanical properties. © 2011 Elsevier Ltd. All rights reserved., The lab support for the NMR studies by Jens Schober and Cornelia Willax is gratefully acknowledged. FV thanks the economical support of the Spanish Ministry of Science and Innovation through the FPU doctoral program.

Disturbances have been recognized as a key factor shaping the species composition, structure and dynamics of natural forest ecosystems. In Europe, where forests driven by spontaneous processes have survived in relic form, knowledge about natural disturbance regimes is still fragmentary. To expand this knowledge, we reconstructed stand-level growth and analyzed the spatio-temporal pattern of release signals in the increment chronologies of individual trees as indicators of disturbance events in the Western Carpathians (Central Europe). The study was carried out in five old-growth forests formed by Fagus sylvatica L., Abies alba Mill. and Picea abies (L.) H. Karst. Depending on the stand, the analyses included tree-ring series of 84–193 trees sampled over areas of 5.9–13.6 ha and aimed at determining (1) the spatio-temporal pattern of disturbance severity over the last two centuries, (2) whether disturbances have been synchronized in time across the study sites and (3) whether disturbances have induced pulsed dynamics of stand development manifested as fluctuations in radial tree increment at the level of entire stands. In the period 1850–2010, the percentage of decades with the proportion of released trees

Every living organism involves biological membranes one way or another, which are important in most biological processes and cellular functions. All of these are dramatically manipulated by not only the sizes and numbers of domains (lipid rafts) but also their lateral organization and phase dynamics in biomembranes. In this article, we discuss the recent findings on domain formation and phase transition behaviors in phospholipid mixtures containing cholesterol and relate to membrane lateral heterogeneity. Thermodynamic forces and considerations regulating in-plane as well as out-of-plane domain structures and interactions in lipid monolayers and bilayers are described. Compositional symmetry and asymmetry between inner and outer leaflets in biomembranes are also considered.

The formation of spatially repetitive structures along the growth axis of a developing embryo is a common theme in developmental biology. Here we apply the novel flow-distributed oscillator (FDO) mechanism of wave pattern formation to the problem of axial segmentation in general and to somitogenesis in particular. We argue that the conditions for formation of FDO waves are satisfied during somitogenesis in the chick and mouse and that the waves of gene expression observed in these species arise from phase dynamics in a growing oscillatory medium. We substantiate this claim by showing that the FDO mechanism allows the waves to be mimicked by an inorganic experiment and that it predicts a wavelength that coincides with that observed experimentally. To see whether the FDO mechanism is compatible with other aspects of somitogenesis, we construct an FDO-based model of somitogenesis and successfully test it against a number of experimental observations, including the effect of heat shock. Our analysis provides a rigorous physical basis for the hypothesis that the phase dynamics of a segmental clock controls important stages of segmentation during somitogenesis in the chick and mouse as well as in other organisms that undergo segmentation during their axial growth.

Using the previous approach outlined in Ratliff and Bridges (2016, 2015), a novel method is presented to derive the fifth order Kadomtsev–Petviashvili(KP) equation from periodic wavetrains. As a result, the coefficients and criterion for the fifth order KP to emerge take a universal form that can be determined a-priori, relating to the system’s conservation laws and the termination of a Jordan chain. Moreover, the analysis reveals that generically a mixed dispersive term q X X X Y appears within the final phase equation. The theory presented here is complimented by an example from the context of flexural gravity waves in shallow water and a higher order Nonlinear Schrodinger model relevant in plasma physics, demonstrating how the coefficients in this model are determined via elementary calculations.

In the quasi-one-dimensional mixed-stack organic charge-transfer complex, TTF-CA, photoirradiation is known to trigger transitions between the neutral and ionic phases. Here we use a one-dimensional extended Peierls–Hubbard model with alternating potentials and calculate the mean-field dynamics of charge density coupled with that of lattice displacements. We show qualitative differences between the photoinduced ionic-to-neutral and neutral-to-ionic transitions, which are consistent with recent experimental findings. That is, the ionic-to-neutral transition proceeds cooperatively, characterized by threshold behavior, while the neutral-to-ionic transition proceeds uncooperatively, characterized by linear behavior. The threshold absorption in the former depends on the strength or the duration of the pulse. The coherence during the transition dynamics is also different between the two transitions. In the ionic-to-neutral transition, a clear interference effect is observed as a function of the interval when the pulse is spilt into two.

This article presents the phase dynamics of an inline long Josephson junction in voltage state under the influence of constant external magnetic field. Fractional calculus approach is used to model the evolution of the phase difference between the macroscopic wave functions of the two superconductors across the junction. The governing non-linear partial differential equation is then solved using finite difference-finite element schemes. Other quantities of interest like Josephson current density and voltage across the junction are also computed. The effects of various parameters in the model on phase difference,Josephson current density and voltage are analyzed graphically with the help of numerical simulations.

For αβ>−1, stable time periodic solutions A(X,T)=AqeiqX+iωqT are the locally preferred planform for the complex Ginzburg–Landau equation ∂ T A=A+(1+iα)∂ X 2 A−(1+iβ)A|A| 2 . In order to describe the spatial global behavior, an evolution equation for the local wave number q can be derived formally. The local wave number q satisfies approximately a conservation law ∂τq=∂ξh(q). It is the purpose of this paper to explain the extent to which the conservation law is valid by proving estimates for this formal approximation.

The simplified models of neural networks based on biophysical Hodgkin–Huxley neurons are studied with a focus on coherent-phase dynamics. In our approach, each neuron is considered as a nonlinear oscillator, and collective dynamics of a mesoscopic network of neural oscillators are studied using the methods of nonlinear dynamics. We explore the mechanisms for synchrony, clustering and their breakup in the synaptic parameter space and discuss implications to temporal aspects of neural-information processing.

We construct a theory of dynamical behavior in intrinsic Josephson junction stacks with multigap superconducting layers. The theory predicts the existence of two kinds of phase modes, one of which is the Josephson-plasma mode and other of which is the Leggett’s mode. We discuss a cooperative phenomena induced by inter-band Josephson coupling in addition to capacitive and inductive couplings between the superconducting layers.

In this study we present an investigation on the impact of sparger configuration and fluid properties on the local gas phase dynamics for up to 17% total gas holdup. Experiments in a bubble column with 100 mm inner diameter were conducted with deionized water and NaOH solution of up to cNaOH = 32 mmol·l−1. Ultrafast X-ray computed tomography (UFXCT) was applied to obtain local hydrodynamic parameters, such as gas holdup distribution, bubble sizes and average bubble rise velocities. Radial gas holdup profiles show wall peaking, which is attributed to the uniform bubbly flow regime generated by the needle sparger used in this study. The addition of NaOH leads to similar gas holdup values but significant changes on local bubbly dynamics, such as bubble size distribution and axial gas phase velocity. The Sauter mean diameter was found to decrease with increasing concentration of NaOH, whereby the decrease is larger at higher gas flow rate.

In this work, we investigate the dynamics of vortex-induced vibration of an elastically mounted cylinder with very low values of mass and damping. We use two methods to investigate this canonical problem: first we calculate the instantaneous phase between the cylinder motion and the fluid forcing; second we decompose the total hydrodynamic force into drag and lift components that act along and normal to, respectively, the instantaneous effective angle of attack. We focus on the phase dynamics in the large-amplitude–response range, consisting of the initial, upper and lower “branches” of response. The instantaneous phase between the transverse force and displacement shows repeated phase slips separating periods of constant, or continuous-drifting, phase in the second half of the upper branch. The phase between the lift component and displacement shows strong phase locking throughout the large-amplitude range – the average phase varies linearly with the primary frequency – however the modulation of this phase is largest in the second half of the upper branch. These observations suggest that the large-amplitude–response dynamics is driven by two distinct limit cycles – one that is stable over a very small range of reduced velocity at the beginning of the upper branch, and another that consists of the lower branch. The chaotic oscillation between them – the majority of the upper branch – occurs when neither limit cycle is stable. The transition between the upper and lower branches is marked by intermittent switching with epochs of time where different states exist at a constant reduced velocity. These different states are clearly apparent in the phase between the lift and displacement, illustrating the utility of the force decomposition employed. The decomposed force measurements also show that the drag component acts as a damping factor whereas the lift component provides the necessary fluid excitation for free vibration to be sustained.

The liquid-phase processes occurring during fuel droplet combustion are important in deciding the behaviour of the overall combustion process, especially, for the binary fuel droplets. Hence, understanding these processes is essential for explaining the combustion of the binary fuel droplet. However, experimental investigation of such processes is not easily accomplishable due to the very short period of time available for tracking them within the finely small fuel droplet. In the present work, a high speed imaging and subsequent image processing leading to quantitative analysis of the binary fuel droplet combustion including liquid-phase dynamics are performed. Two categories of binary fuels – in which diesel is the base fuel – are prepared and utilized. The first category is biodiesel/diesel and bioethanol/diesel blends, while the second category is the water-in-diesel and diesel-in-water emulsions. Specific optical setup is developed and used for tracking droplet combustion. The resulting magnification of the droplet images is up to 30 times the real size, offering the possibility of droplet interior visualization at high imaging rates up (to 40,000 fps). With the aid of this setup, spatial and temporal tracking of nucleation, bubble formation, puffing, microexplosion, and secondary atomization during the combustion of two adjacent binary fuel droplets are performed. The burning rate constants are evaluated and found to have the same trends as the isolated droplet combustion. However, the ratio of the droplet burning rate constant of the interactive droplet combustion to that of the isolated droplet combustion is higher than unity. This is the same for the nucleation rate within the interacting fuel droplets.

The idea of phase dynamics originally considered for regular non-equilibrium patterns is applied to irregular patterns. In the dissipation-dominated regime, a slow modulation of irregular pattern is shown to decay in time according to the diffusion law. Possible relevance of this result for the ultra-slow diffusion modes observed in glass-forming systems is discussed. In this connection we speculate about a possibility of appearance of some sorts of soft structures resembling quasi-periodic microcrystalline states in glass-forming systems.

High critical temperature superconductors (HTS) based devices can have impact in the study of the phase dynamics of Josephson junctions (JJs) thanks to the wide range of junction parameters they offer and to their unconventional properties. Measurements of current-voltage characteristics and of switching current distributions constitute a direct way to classify different regimes of the phase dynamics and of the transport, also in nontrivial case of the moderately damped regime (MDR). MDR is going to be more and more common in JJs with advances in nanopatterning superconductors and synthesizing novel hybrid systems. Distinctive signatures of macroscopic quantum tunneling and of thermal activation in presence of different tunable levels of dissipation have been detected in YBCO grain boundary JJs. Experimental data are supported by Monte Carlo simulations of the phase dynamics, in a wide range of temperatures and dissipation levels. This allows us to quantify dissipation in the MDR and partially reconstruct a phase diagram as guideline for a wide range of moderately damped systems. (C) 2014 Elsevier B.V. All rights reserved.

Understanding the coupled two-phase dynamics in the cathode gas diffusion layer (GDL) and gas channel (GC) is of vital importance to optimize water management and to improve performance of proton exchange membrane fuel cell (PEMFC). However, it is difficult to directly observe the two-phase flow in the cathode of PEMFC because the GDL is opaque and has complex structures. To circumvent this issue, a similarity experiment model is developed in the present study. Based on the soft lithography technology, we fabricate a microfluidic device composed of a duct representing the GC and a bundle of tubes representing the GDL. Emergence of liquid droplets from these tubes into the duct gas stream is conducted to mimic the two-phase dynamics in the GDL and the GC. With this similarity experiment, we explore the influences of the gas flow rate on the liquid water flow in the cathode of PEMFC as well as the effects of the GDL surface defects on the two-phase dynamics in the GC. The two-phase flows in the hydrophilic and hydrophobic systems are also compared to elucidate the effects of wettability on water management of PEMFCs.

We have studied the phase properties of initially coherent light interacting with two identical two-level atoms using the Hermitian phase operator of Pegg and Barnett. The results show that, in a certain initial state of the atoms, the field would, to a certain extent, preserve its order in phase, even for a long interaction time with the two atoms.

In this paper we present an electronic system designed to emulate neural networks. Two major restrictions are assumed: discrete synapses (+1,0,−1) and threshold-type neurons. Drawbacks given by restrictions are solved with a more complex learning algorithm that maps real valued configurations for synapses into bipolar ones. The central unit of the system is an ASIC designed in accordance with a new sequential dynamics, which is faster and with better recall characteristics. As a result, the system designed has a fast recall phase and a large number of neurons. A handwritten OCR system is being designed.

With the aim of synthesizing the mixed nanoparticle system x In 2 O 3 –(1− x )SnO 2 over all molar concentration range 0 ≤ x ≤ 1, Δ x = 0.1, we performed hydrothermal supercritical experiments on indium–tin hydrogel resulted from InCl 3 –SnCl 4 water solution. Nanophases isostructural with InOOH and SnO 2 were obtained by hydrothermal reaction at 400 °C, in the molar concentration range of 0.1 ≤ x ≤ 0.7; at x = 0.8 and x = 0.9 only one phase, isostructural with InOOH, was observed. Samples calcined at 500 °C with x in the range of 0.2 ≤ x ≤ 0.7 contain a nanoscaled phase isostructural with rhombohedral In 2 O 3 and a second one isostructural with tetrahedral SnO 2 . At x = 0.8 and x = 0.9 only one phase isostructural with rhombohedral In 2 O 3 appears: rhombohedral ITO phase. The determined band gap energies could recommend the rhombohedral ITO structure for visible light photocatalytic applications. The phase dynamics together with the concentration range for existence of the solid solutions in the InOOH–SnO 2 and In 2 O 3 –SnO 2 composite semiconducting nanoparticle systems have been evidenced and discussed.