Resonant absorption of shear instabilities in flow systems with energy dissipation

It is shown that hydrodynamic and electrohydrodynamic waves excited in two-layer dissipative systems due to shear instabilities experience resonant absorption of two types: at the rotational frequency of particles of the medium and the frequency of their collision with the lattice.     

Resonant enhancement and dissipation in nonequilibrium van der Waals forces

Dispersion forces between molecules that are in relative motion, coupled to baths at different temperatures, or in excited states, are calculated using a Green function Liouville space expansion that extends the celebrated McLachlan response theory to the nonlinear regime. Our dynamical theory is applicable to systems that may be in any initial nonequilibrium state and that are subject to an arbitrary time-dependent coupling. In contrast to equilibrium forces which are attractive, nonequilibrium forces may be attractive or repulsive, exhibit chemically specific resonances, are far stronger, and may be nonconservative (with either positive or negative dissipation).     

Adiabatic perturbations for compactons under dissipation and numerically-induced dissipation

Compacton propagation under dissipation shows amplitude damping and the generation of tails. The numerical simulation of compactons by means of dissipative schemes also show the same behaviors. The truncation error terms of a numerical method can be considered as a perturbation of the original partial differential equation and perturbation methods can be applied to its analysis. For dissipative schemes, or when artificial dissipation is added, the adiabatic perturbation method yields evolution equations for the amplitude loss in the numerical solution and the amplitude of the numerically-induced tails. In this paper, such methods are applied to the K(2,2)$K(2\text{,}2)$ Rosenau–Hyman equation, showing a very good agreement between perturbative and numerical results.     

Resonant enhancement of neutrinoless double-electron capture in 152Gd

In the search for the nuclide with the largest probability for neutrinoless double-electron capture, we have determined the Q(??) value between the ground states of (152)Gd and (152)Sm by Penning-trap mass-ratio measurements. The new Q(??) value of 55.70(18) keV results in a half-life of 10(26) yr for a 1 eV neutrino mass. With this smallest half-life among known 0ν?? transitions, (152)Gd is a promising candidate for the search for neutrinoless double-electron capture.     

Improved power distribution in diffuse Indoor Optical Wireless systems employing multiple transmitter configurations

Power distribution plays a vital role in the performance of diffuse indoor optical wireless systems. Commonly used single-transmitter diffuse systems result in non-uniform power distribution patterns. We propose the use of multiple transmitters, suitably placed at different locations on the ceiling, as a technique to obtain fairly uniform power distribution on the floor. In this paper we use an extension of the recursive method developed by J.R. Barry and J.M. Kahn (IEEE Sel. Area Commun. 1 367, 1993), to compute multi-path impulse response and power distribution. We show that placement of the transmitters is crucial in achieving near uniform power distribution. Effect of the number of transmitters on power distribution and the channel bandwidth are also examined.     

The effect of pressure on orbital electron capture

The effect of pressure on the decay rate by electron capture has been estimated on the basis of certain simplifying assumptions. For the case of ⁷Be the order-of-magnitude agreement is found.     

Resonant capture of low-energy electrons by molecules of phthalide derivatives

The interaction of 0–15 eV electrons with organic molecules modeling the monomeric units of polyarylenephthalides, where charge instability has been observed, is studied by negative-ion mass spectrometry. It is found that the C-O bond is unstable with respect to the interaction of the molecule with low-energy electrons and, in consequence, there is a high probability that this bond will break, which could explain the unusual electrophysical properties of these polymers. Pis’ma Zh. éksp. Teor. Fiz. 64, No. 6, 402–406 (25 September 1996) Deceased.     

Metaheuristic optimization-based identification of fractional-order systems under stable distribution noises

This research investigates the identification problem of fractional-order chaotic systems under stable distribution noises. A powerful metaheuristic optimization method called composite differential evolution is used for the identification of the fractional-order Lorenz and Chen systems in the noisy environment, where the structure, parameters, orders and initial values of the systems are all unknown. The identification accuracy is examined when the noise follows the three special cases of stable distributions, i.e., Gaussian, Cauchy and Lévy distributions. In addition, the impact of the four parameters of stable distributions on the identification accuracy is discussed. The experimental results show that the identification error becomes larger when the noise switches from Gaussian to Cauchy and Lévy distributions. The results also turn out that the location of the stable distribution noise plays the most substantial role in the identification accuracy.     

After effects of orbital electron capture in Co spinels

In this work we present several Mössbauer emission spectra of the spinels ⁵⁷CoMn₂O₄, ⁵⁷CoY₂O₄ and ⁵⁷CoV₂O₄ prepared under well determined conditions. The consequences of electronic capture in ⁵⁷Co in spinels are studied. It is found that the appearance of anomalous charge states is connected with the macroscopic properties of the spinel.     

207Bi L-subshell orbital electron capture probabilities and decay energy

The L₁ subshell orbital electron capture probability P_L1 in the decay of 33.4 y ²⁰⁷Bi to the 2339.89 keV level in ²⁰⁷Pb is measured to be 0.518 ± 0.081 (95% confidence) by a new method in which L₁ subshell characteristic X-rays in the L_γ X-ray peak are observed in an Xγt coincidence mode with 1770.23 keV γ-rays. The value of P_L2is 0.047 ± 0.015 (95% confidence). From these results a value of Q_EC = 39_-8⁺²¹ keV is obtained for capture transitions to the 2339.89 keV level. The absence of K-capture to this level also is established by absence of K X-rays in coincidence with 1770.23 keV γ-rays.     

Enhanced quantum resources via two distant atom-cavity systems under the influence of atomic dissipation

Quantum resources such as entanglement and coherence are the holy grail for modern quantum technologies.Although the unwanted environmental effects tackle quantum information processing tasks,suprisingly these key quantum resources may be protected and even enhanced by the implementation of some special hybrid open quantum systems.Here,we aim to show how a dissipative atom-cavity-system can be accomplished to generate enhanced quantum resources.To do so,we consider a couple of dissipative cavities,where each one contains two effective two-level atoms interacting with a single-mode cavity field.In practical applications,a classical laser field may be applied to drive each atomic subsystem.After driving the system,a Bell-state measurement is performed on the output of the system to quantify the entanglement and coherence.The obtained results reveal that the remote entanglement and coherence between the atoms existing inside the two distant cavities are not only enhanced,but can be stabilized,even under the action of dissipation.In contrast,the local entanglement between two atoms inside each dissipative cavity attenuates due to the presence of unwanted environmental effects.Nevertheless,the local coherence may show the same behavior as the remote coherence.Besides,the system provides the steady state entanglement in various interaction regimes,particularly in the strong atom-cavity coupling and with relatively large detuning.More interestingly,our numerical analyses demonstrate that the system may show a memory effect due to the fact that the death and revival of the entanglement take place during the interaction.Our proposed model may find potential applications for the implementation of long distance quantum networks.In particular,it facilitates the distribution of quantum resources between the nodes of large-scale quantum networks for secure communication.     

空气强制对流冷却工况下多芯片散热过程数值模拟

建立强制空气对流冷却多个电子芯片的理论模型,采用控制容积法离散控制方程组并进行数值求解,得到芯片和固体基板的温度场,分析了冷却空气流过电子芯片的流场,同时在考虑芯片与基板的接触热阻的情况下,计算了芯片的温度分布,并与不考虑其接触热阻的数值模拟结果进行了比较。研究表明离冷却空气进口最远的芯片温度最高;空气在芯片之间流动会产生回流现象;当电子芯片与固体基板接触热阻较小时,芯片工作产生的热量能很好地通过固体基板传递出去,而当电子芯片与固体基板接触热阻较大时,热量传递会相对困难,使得芯片工作时产生的热量不能及时带走,芯片容易超温工作。     

Observation of non-exponential orbital electron capture decays of hydrogen-like Pr and Pm ions

We report on time-modulated two-body weak decays observed in the orbital electron capture of hydrogen-like ¹⁴⁰Pr⁵⁹⁺ and ¹⁴²Pm⁶⁰⁺ ions coasting in an ion storage ring. Using non-destructive single ion, time-resolved Schottky mass spectrometry we found that the expected exponential decay is modulated in time with a modulation period of about 7 seconds for both systems. Tentatively this observation is attributed to the coherent superposition of finite mass eigenstates of the electron neutrinos from the weak decay into a two-body final state.     

Quantum chaos, thermalization and dissipation in nuclear systems

Nuclei have complex energy-level sequence with statistical properties in agreement with canonical random matrix theory. This agreement appears when the one-particle one-hole states are mixed completely with two-particle two-hole states. In the transition, there is a new universality which we present here, bringing about a relation between dynamics and statistics. We summarize also the role of chaos in thermalization and dissipation in isolated systems like nuclei. The methods used to bring forth this understanding emerge from random matrix theory, semiclassical physics, and the theory of dynamical systems.     

Resonant Rayleigh scattering of exciton-polaritons in multiple quantum wells

A theoretical concept of resonant Rayleigh scattering (RRS) of exciton-polaritons in multiple quantum wells (QWs) is presented. The optical coupling between excitons in different QWs can strongly affect the RRS dynamics, giving rise to characteristic temporal oscillations on a picosecond scale. Bragg and anti-Bragg arranged QW structures with the same excitonic parameters are predicted to have drastically different RRS spectra. Experimental data on the RRS from multiple QWs show the predicted strong temporal oscillations at small scattering angles, which are well explained by the presented theory.     

Magnetic configurations of hybrid ferromagnetic dot–superconductor systems

In-plane single domain and vortex magnetization configurations of the magnetic dot in the hybrid superconductor–ferromagnet system are considered. Single domain configuration energy shift due to the presence of superconductor is calculated. The change of the phase curve of the ferromagnetic dot magnetization due to the repulsion of the magnetic field by the superconductor is obtained. Up to the two-fold decrease of the ferromagnetic dot critical radius due to the presence of the superconductor is predicted.