Study of the Activation Barrier of Crystallization of a Metastable Liquid Using Metadynamics

Physics of the Solid State - Crystallization of a weakly supercooled Lennard-Jones liquid has been investigated by molecular-dynamics simulation using metadynamics. The Steinhardt order parameter...     

A Possible Mechanism for the Formation of Unwettable Dry Spots on the Heated Surface under Nucleate Boiling: Part I. Basic Models and Characteristics of Heterogeneous Nucleate Pool Boiling at a Low Pressure

The problems associated with the physics of heterogeneous pool boiling at a low pressure on a flat horizontal surface are considered. The examples of parametric mismatch between the trends are connected with the thermophysical properties and wall surface microgeometry, with the size of the working area, with the affected zone of a growing bubble, and with the contact angle at the interface between the liquid, solid, and vapor phases. A conclusion is drawn concerning the possible causes of ambiguity in the results of the simulation of nucleate pool boiling modes under calculation of the individual contribution of each of the heat transfer mechanisms (convection, liquid microlayer evaporation, and rearrangement of the thermal boundary layer after bubble detachment). It is emphasized that the problem should be solved in the 3D conjugate formulation.     

An Experimental Study of the Two-Phase Flow Adjacent to a Wire in Nucleate Boiling Under an Electric Field

An experimental study of the two-phase flow near a heated wire in nucleate pool boiling is presented. A nonuniform electric field of cylindrical geometry was imposed to the heater. The two-phase flow parameters were measured using specifically developed local phase-detection optical probes. The study includes experiments varying the vertical distance from the heater (z) and measurements of the void fraction and the impact rate in a plane perpendicular to the heater (y-z). The results show that the void fraction decreases with applied voltage and with z. The dependence of the void fraction and the impact rate with heat flux is complex, with a strong decrement in the impact rate and void fraction near the critical heat flux when voltage is applied. The maximum void fraction and impact rate move from the vertical centerline (z) to a position 3 heater radii away.     

On the Becker/Döring Theory of Nucleation of Liquid Droplets in Solids

Nucleation of liquid precipitates in semi-insulating GaAs is accompanied by deviatoric stresses resulting from the liquid/solid misfit. A competition of surface tension and stress deviators at the interface determines the nucleation barrier.The evolution of liquid precipitates in semi-insulating GaAs is due to diffusional processes in the vicinity of the droplet. The diffusion flux results from a competition of chemical and mechanical driving forces.The size distribution of the precipitates is determined by a Becker--Dö-ring system. The study of its properties in the presence of deviatoric stresses is the subject of this study. The main tasks of this study are: (i) We propose a new Becker/Döring model that takes thermomechanical coupling into account. (ii) We compare the current model with already existing models from the literature. Irrespective of the incorporation of mechanical stresses, the various models differ due to different environments where the evolution of precipitates takes place. (iii) We determine the structure of equilibrium solutions according to the Becker/Döring model, and we compare these solutions with those that result from equilibrium thermodynamics.     

运用严格耦合波理论计算平面电介质光栅的衍射效率

本文阐述了严格耦合波理论的基本思想。针对横电波的情况，详细分析了运用严格耦合波理论实现光栅衍射效率计算的方法，并且进一步给出了编制计算衍射效率程序的步骤。通过一个具体计算实例表明：各衍射级分布的光能量之和等于入射光的能量，满足能量守恒定律，从而证实了计算结果的正确性。     

A Theory for the Quantitative Estimation of Bed Load Transport Using Radioisotopes

In this paper an attempt has been made to develop a simple theory for the application of radiotracer techniques to estimate the quantum of bed material transported in rivers, estuaries, etc. The emphasis is mainly on the physical concepts involved. Certain assumptyions made in the theory are later verified experimentally.     

Self-Similarity in the Problem of Laminar Film Boiling on a Vertical Surface Submerged in a Large Volume of a Liquid

Technical Physics - Using the methods of self-similarity for a laminar free-convective film boiling on a vertical finite-length surface submerged into a large volume of an arbitrarily subcooled...     

On the Possibility of Using a Single Time Realization for Investigating Noise from Vortex Rings

Acoustical Physics - The possibility of using a single time realization of a vortex ring to study its aeroacoustic properties is considered. For each realization, averaging is performed over six...     

The Kinetics of the Liquid Phase Nucleation in a Stretched FCC Crystal: A Molecular Dynamics Simulation

Physics of the Solid State - The kinetics of a spontaneous formation of liquid phase in a stretched (superheated) Lennard-Jones fcc crystal is studied. Molecular dynamics experiments are used to...     

On the Possibility of Using a Filament RF Discharge for Analyzing the Atomic Composition of Organic Compounds

Physics of Particles and Nuclei Letters - A method for analyzing the atomic composition of organic compounds based on a filament RF discharge is proposed. The sample is prepared by heating it to...     

On the Possibility of a Significant Increase in the Storage Time of Ultracold Neutrons in Traps Coated with a Liquid Helium Film

JETP Letters - Birefringent microstructures recorded at a fixed depth under the action of laser pulses with a wavelength of 1030 nm, different durations in the range of 0.3–3.8 ps, and...     

Calculation of the Electron Efficiency for a Two-Cavity Gyroklystron Amplifier by Using a Self-Consistent Code

The beam-wave interaction in a Ka-band, two-cavity fundamental gyroklystron amplifier is studied by using a self-consistent nonlinear simulation code. The electron efficiency for this gyroklystron amplifier is calculated, and the effect of various parameters, such as beam voltage, beam current, electron guiding center radius, velocity pitch ratio and drift tube length on the electron efficiency is discussed in detail.     

Estimation of the Seabed Parameters in a Nonuniform Waveguide Using the Matched-Field Method

Radiophysics and Quantum Electronics - We estimate geoacoustic parameters of a layered bottom in a shallow waveguide, which is nonuniform along the path, using the data of the full-scale experiment...     

On the Existence of Hypersonic Electrostatic Solitons (Estimation of Limiting Mach Numbers of Ion-Sound Solitons in a Warm Plasma)

Journal of Experimental and Theoretical Physics - We develop a nonlinear theory of ion-sound waves in a collisionless warm electron–ion plasma. The theory is based on analysis of the Sagdeev...     

Study of the Possibility Of Replacing an Integrated Airframe with a Flat Polygonal Screen to Estimate The Efficiency of Noise Screening of Engines Using Geometric Diffraction Theory

Acoustical Physics - Using the example of an integrated airframe, we performed a computational and experimental study of the possibility of using geometric diffraction theory (GDT) to calculate the...     

An Analytical Calculation of the Equation of State and the Critical Point in a Dense Classical Fluid of Charged Hard Spheres

A theoretical expression for the equation of state is developed which is based on the mass action law, the Carnahan-Starling expression for the hard-sphere contributions and the mean-spherical approximation for the Coulombic interactions. Numerical calculations of the pressure and the critical data show good agreement with other methods (HNC, MC etc.).     

用改进的格点哈密顿量计算2+1维SU(2)规范场胶球质量

用改进的格点哈密顿量和截断本征方程法计算2+1维SU(2)规范场胶球质量,结果在广阔的耦合区内(1.0≤1/g²≤8.0)显示出极好的标度行为.     

On the Possibility of Increasing the Noise Immunity in Detecting Sound Signals in a Shallow Water Using Energy and Phase Invariants

Acoustical Physics - Differential equations are obtained and analyzed to describe the dynamics of “ridges” constructed from zones of interference maxima and sound pressure equal phase...     

Classical limit of the probability density for a perturbed change in the Hamiltonian

The stationary perturbation series is derived from the time-dependent perturbation series up to any order by using a formula derived from the theory of divergent series. The probability density of the perturbed state turns out as the evolution of the density operator of the pure unperturbed initial state as 0. This result, for 0, indicates that the particle moves in the classical trajectory with the HamiltonianH=H ₀+V immediately afterV is turned on, if it is in the trajectory ofH ₀ initially. This confirms the classical dynamics. Further, the adiabatic theorem is introduced in order to get the same conclusion for arbitrary finite potentialV.This paper was developed from part of a report (Su, 1968) which was supported by National Science Council, Republic of China.