Synchronous chaos in the coupled system of two logistic maps

Synchronous chaos is investigated in the coupled system of two Logistic maps. Although the diffusive coupling admits all synchronized motions, the stabilities of their configurations are dependent on the transverse Lyapunov exponents while independent of the longitudinal Lyapunov exponents. It is shown that synchronous chaos is structurally stable with respect to the system parameters. The mean motion is the pseudo-orbit of an individual local map so that its dynamics can be described by the local map. (C) 2004 Elsevier Ltd. All rights reserved.

A novel oblique detonation structure and its stability

Oblique detonation structures induced by the wedge in the supersonic combustible gas mixtures are simulated numerically. The results show that the stationary oblique detonation structures are influenced by the gas flow Mach number, and a novel critical oblique detonation structure, which is characterized by a more complicated wave system, appears in the low Mach number cases. By introducing the inflow disturbance, its nonstationary evolution process is illustrated and its stability is verified.

Viscosity-induced mode splitting and potential energy criterion for mode stability

This paper points out that viscosity can induce mode splitting in a uniform infinite cylinder of an incompressible fluid with self-gravitation, and that the potential energy criterion cannot be appropriate to all normal modes obtained, i.e., there will be stable modes with negative potential energy (<0). Therefore the condition >0 is not necessary, although sufficient, for the stability of a mode in an incompressible static fluid or magnetohydrodynamics (MHD) system, which is a correction of both Hare's [Philos. Mag. 8, 1305 (1959)] and Chandrasekhar's [Hydrodynamic and Hydromagnetic Stability (Oxford U.P., Oxford, 1961), p. 604] stability criterion for a mode. These results can also be extended to compressible systems with a polytropic exponent.

On the non-linear stability theory of spinning solid bodies with liquid-filled cavities and its application to the columbus problem

In this paper, we first present a system of differential-integral equations for the largedisturbance to the general case that any arbitrarily shaped solid body with a cavity contain-ing viscous liquid rotates uniformly around the principal axis of inertia, and then develop aweakly non-linear stability theory by the Lyapunov direct approach. Applying this theoryto the Columbus problem, we have proved the consistency between the theory and Kelvin'sexperiments.

Oscillatory Instability of Rayleigh-Marangoni-Benard Convection in Two-Layer System

The convective instabilities in two or more superposed layers heated from below were studied extensively by many scientists due to several interfacial phenomena in nature and crystal growth application. Most works of them were performed mainly on the instability behaviors induced only by buoyancy force, especially on the oscillatory behavior at onset of convection (see Gershuni et. Al.(1982), Renardy et. Al. (1985,2000), Rasenat et. Al. (1989), and Colinet et. Al.(1994)) . But the unstable situations of multi-layer liquid convection will become more complicated and interesting while considering at the same time the buoyancy effect combined with thermocapillary effect. This is the case in the gravity reduced field or thin liquid layer where the thermocapillary effect is as important as buoyancy effect. The objective of this study was to investigate theoretically the interaction between Rayleigh-Bénard instability and pure Marangoni instability in a two-layer system, and more attention focus on the oscillatory instability both at the onset of convection and with increasing supercriticality. Oscillatory behavious of Rayleigh-Marangoni-Bénard convective instability (R-M-B instability) and flow patterns are presented in the two-layer system of Silicon Oil (10cSt) over Fluorinert (FC70) for a larger various range of two-layer depth ratios (Hr=Hupper/Hdown) from 0.2 to 5.0. Both linear instability analysis and 2D numerical simulation (A=L/H=10) show that the instability of the system depends strongly on the depth ratio of two-layer liquids. The oscillatory instability regime at the onset of R-M-B convection are found theoretically in different regions of layer thickness ratio for different two-layer depth H=12,6,4,3mm. The neutral stability curve of the system displaces to right while we consider the Marangoni effect at the interface in comparison with the Rayleigh-Bénard instability of the system without the Marangoni effect (Ma=0). The numerical results show different regimes of the developing of convection in the two-layer system for different thickness ratios and some differences at the onset of pure Marangoni convection and the onset of Rayleigh-Bénard convections in two-layer liquids. Both traveling wave and standing wave were detected in the oscillatory instability regime due to the competition between Rayleigh-Bénard instability and Marangoni effect. The mechanism of the standing wave formation in the system is presented numerically in this paper. The oscillating standing wave results in the competition of the intermediate Marangoni cell and the Rayleigh convective rolls. In the two-layer system of 47v2 silicone oil over water, a transition form the steady instability to the oscillatory instability of the Rayleigh-Marangoni-Bénard Convection was found numerically above the onset of convection for ε=0.9 and Hr=0.5. We propose that this oscillatory mechanism is possible to explain the experimental observation of Degen et. Al.(1998). Experimental work in comparison with our theoretical findings on the two-layer Rayleigh-Marangoni-Bénard convection with thinner depth for H<6mm will be carried out in the near future, and more attention will be paid to new oscillatory instability regimes possible in the influence of thermocapillary effects on the competition of two-layer liquids

The Convective Instabilities in a Liquid-Vapor System with a Non-equilibrium Evaporation Interface

Rayleigh-Marangoni-B,nard instability in a system consisting of a horizontal liquid layer and its own vapor has been investigated. The two layers are separated by a deformable evaporation interface. A linear stability analysis is carried out to study the convective instability during evaporation. In previous works, the interface is assumed to be under equilibrium state. In contrast with previous works, we give up the equilibrium assumption and use Hertz-Knudsen's relation to describe the phase change under non-equilibrium state. The influence of Marangoni effect, gravitational effect, degree of non-equilibrium and the dynamics of the vapor on the instability are discussed.

Stability against crystallization and spectroscopic properties of Tm3+ doped fluorophosphate glasses

Fluorophosphate glasses with various content of Al(PO3)(3) were prepared. With the increment of Al(PO3)(3) content, density decreases while refractive index increases, and transition temperature, crystallization peak temperature and melt temperature increase which were suggested by differential scanning calorimetry. These glasses exhibit the best stability against crystallization with 7-9 mol'Yo Al(PO3)(3) content. Normalized Raman spectra were used to analyze structure and phonon state. The increment of Al(PO3)(3) content does not affect phonon energy but results in the augment of phonon density. Absorption spectra were measured. H-3(6) -> F-3(4) transition exhibits absorption at L band of the third communication window. Compared with the energy of Tm3+ excited states in other glass system, F-3(4) energy of Tm3+ in these glasses is considerable higher and H-3(4) energy is considerable lower, and it can be predicted that emission band of H-3(4) -> F-3(4) transition is close to the amplified band of gain-shift Tm3+ doped fiber amplifier. Analyses of Judd-Ofelt theory suggest when Al(PO3)(3) content is no more than 7 mol%, Judd-Ofelt parameters Omega(t) and the lifetime of H-3(4) energy level of TM3+ vary little with the increment of Al(PO3)(3) content, and when Al(PO3)(3) content is more than 7 mol%, Omega(2) and Omega(6) increase and radiative lifetime of H-3(4) energy level of Tm3+ drops sharply with the increment of Al(PO3)(3) content. (c) 2006 Elsevier B.V. All rights reserved.

Structural investigation on TeO2-BiCl3 glassy system

Glass systems of composition xBiCl(3)-(1-x)TeO2 (x=0.2, 0.4, 0.5 and 0.6, respectively) have been investigated by means of DSC, infrared absorption spectroscopy and Raman spectroscopy in order to obtain information about the transformation of structure, thermal and optical properties in the formation of the glass network. The results confirm that the addition of BiCl3 network former increases the glass forming ability and the optical transmission range. And also from Raman results a structural evolution was observed where the number of structural units described as [TeO3] trigonal pyramids, [TeO3+1] polyhedra and ionic behavior bonds (NBO) increases at the expense of the [TeO4] trigonal bipyramids. Bi3+ ions exist in network structure as [BiO6] or [BiCl6] octahedral coordination. As upconversion luminescence glass host, this glassy system is desired for optical properties but the thermal stability will still be improved. (c) 2005 Elsevier B.V. All rights reserved.

Structure and thermal stability of novel fluorophosphate glasses

A systematic investigation on glass formation in the PbF2-InF3-BaHPO4 ternary system has been carried out. These glasses have characterized by IR spectra, Raman spectra and differential thermal analysis. The results show that the structure of these glasses is mainly affected by BaHPO4 and InF3 contents. With decreasing BaHPO4 content, the glass structure gradually transforms from metaphosphate to polyphosphate. When InF3 content is low, it mainly acts as network modifier, when its content is high; it enters glass matrix and forms In(O,F)(6) groups connecting the polymerized phosphorus oxygen species. PbF2 mainly acts as network modifier in this system. Systematic variations of the glass transition temperature and the thermal stability index agree well with these results. The most stable glass with Delta T = 230 degrees C and S = 21.79 K is obtained. (c) 2004 Elsevier B.V. All rights reserved.

Design and fabrication of color filters for projection display system

Color filters are key components in an optical engine projection display system. In this paper, a new admittance-matching method for designing and fabricating the high performance filters is described, in which the optimized layers are limited to the interfaces between the stack (each combination of quarter-wave-optical-thickness film layers is called a stack) and stack, or between stack and substrate, or between stack and incident medium. This method works well in designing filters containing multiple stacks such as UV-IR cut and broadband filters. The tolerance and angle sensitivity for the designed film stacks are analyzed. The thermal stability of the sample color filters was measured. A good result in optical performance and thermal stability was obtained through the new design approach. (c) 2006 Society of Photo-Optical Instrumentation Engineers.

Design and fabrication of color filters for projection display system

Color filters are key components in an optical engine projection display system. In this paper, a new admittance-matching method for designing and fabricating the high performance filters is described, in which the optimized layers are limited to the interfaces between the stack (each combination of quarter-wave-optical-thickness film layers is called a stack) and stack, or between stack and substrate, or between stack and incident medium. This method works well in designing filters containing multiple stacks such as UV-IR cut and broadband filters. The tolerance and angle sensitivity for the designed film stacks are analyzed. The thermal stability of the sample color filters was measured. A good result in optical performance and thermal stability was obtained through the new design approach. (c) 2006 Society of Photo-Optical Instrumentation Engineers.

Diffusive coevolution and mutualism maintenance mechanisms in a fig-fig wasp system

In reciprocal mutualism systems, the exploitation events by exploiters might disrupt the reciprocal mutualism, wherein one exploiter species might even exclude other coexisting exploiter species over an evolutionary time frame. What remains unclear is how such a community is maintained. Niche partitioning, or spatial heterogeneity among the mutualists and exploiters, is generally believed to enable stability within a mutualistic system. However, our examination of a reciprocal mutualism between a fig species (Ficus racemosa) and its pollinator wasp (Ceratosolen fusciceps) shows that spatial niche partitioning does not sufficiently prevent exploiters from overexploiting the common resource (i.e., the female flowers), because of the considerable niche overlap between the mutualists and exploiters. In response to an exploiter, our experiment shows that the fig can (1) abort syconia-containing flowers that have been galled by the exploiter, Apocryptophagus testacea, which oviposits before the pollinators do; and (2) retain syconia-containing flowers galled by Apocryptophagus mayri, which oviposit later than pollinators. However, as a result of (2), there is decreased development of adult non-pollinators or pollinator species in syconia that have not been sufficiently pollinated, but not aborted. Such discriminative abortion of figs or reduction in offspring development of exploiters while rewarding cooperative individuals with higher offspring development by the fig will increase the fitness of cooperative pollinating wasps, but decrease the fitness of exploiters. The fig fig wasp interactions are diffusively coevolved, a case in which fig wasps diversify their genotype, phenotype, or behavior as a result of competition between wasps, while figs diverge their strategies to facilitate the evolution of cooperative fig waps or lessen the detrimental behavior by associated fig wasps. In habitats or syconia that suffer overexploitation, discriminative abortion of figs or reduction in the offspring development of exploiters in syconia that are not or not sufficiently pollinated will decrease exploiter fitness and perhaps even drive the population of exploiters to local extinction, enabling the evolution and maintenance of cooperative pollinators through the movement between habitats or syconia (i.e., the metapopulations).

Study of sorption, biodegradation and isomerization of HCH in stimulated sediment/water system

This paper reported the sorption, biodegradation and isomerization of hexachlorocyclohexane (HCH) in laboratory sediment/water system under aerobic and anaerobic conditions, respectively. The effect of organic nutrient addition to the sorption of HCH was also investigated. It indicates that HCH is highly adsorbed on sediments under both conditions. During the tests, the biodegradation and isomerization of HCH were dramatically speeded up after organic nutrient additions, especially in the case of the observation under aerobic condition. It was found, beta-HCH was the most persistent in the environment, that is due to the isomerization of alpha-HCH in a big amount to beta-HCH, besides its chemical stability. (C) 1997 Elsevier Science Ltd.

Stability of GaAs photocathodes under different intensities of illumination

The photocurrent curves of reflection-mode GaAs photocathodes as a function of time, when were illuminated by white light with an intensity of 0, 33 and 100 Ix, respectively, were measured using a multi-information measurement system. The calculated lifetimes of cathodes are 320, 160 and 75 min, respectively, showing that the stability of cathodes degraded with the increase of light intensity. The lifetime of cathode, illuminated by white light with an intensity of 100 Ix, while no photocurrent was being drawn during the illumination, was 100 min. Through comparison, we found that the influence of illumination on cathodes stability is greater than that of photocurrent. The quantum-yield curves of cathodes as a functions of time, when illuminated by white light with an intensity of 33 Ix, were measured also. The measured results show that the shape of the yield curves changes with increasing illumination time due to the faster quantum-yield degradation rate of low energy photons. Based on the revised quantum-efficiency equations for the reflection-mode cathodes, the variation of yield curves are analyzed to be due to the intervalley diffusion of photoelectrons and the evolution of the surface potential barrier profile of the photocathodes during degradation process.

Nonlinear optical properties and thermal stability of the poled polymer NTAB/PEK-c

Films of high glass' transition temperature polymer polyetherketone doped with chromophore 2,2'[4-[(5-nitro-2-thiazolyl)azophenyl]-amino]-bisethanol NTAB) were prepared, poled by the corona-onset poling setup which includes a grid voltage making the surface-charge distribution uniform at elevated temperature. The thickness of the films was measured by the Model 2010 Prism Coupler system. Second harmonic generation d(33) was measured by the second harmonic generation method, and the d33 is 38.12 pm/V at 1064 nm under the absorption correction. The nonlinear optical activity maintains is 80% of its initial value. (C) 2002 Elsevier Science B.V. All rights reserved.