Basic properties of free stratified flows

Results of analytical studies of the governing equations of stratified rotating fluids based on the unification of theories of continuous and discrete groups, perturbations and modern numerical visualizations are described. Symmetries of basic systems and their simplified versions, different approximations and constitutive turbulent models are compared. A new method to calculate discrete groups analytically, which does not need a preliminary search for continuous groups, is developed. As an example of the practical use of the developed algorithm, a complete classification of cellular and roll structures of Bénard convection is presented. A complete classification of 3D periodic motions in compressible viscous stratified and rotating fluids, including regular (wave) and singular elements, is performed by perturbation methods. In all cases, in a viscous fluid, besides waves there are two different periodic boundary layers. In a homogeneous fluid the split boundary layers are merged, thus forming a joint doubly-degenerate structure. Stratification and rotation reduce the degeneration of the 3D periodic boundary layers. Calculations of a 3D periodic wave beam emitted by an oscillating part of a sloping plane are visualized by a computer-graphics method. The existence of thin extended components on the edges of the 3D wave cone is demonstrated.     

Temporal presentation protocols in stereoscopic displays: Flicker visibility, perceived motion, and perceived depth

Most stereoscopic displays rely on field-sequential presentation to present different images to the left and right eyes. With sequential presentation, images are delivered to each eye in alternation with dark intervals, and each eye receives its images in counter phase with the other eye. This type of presentation can exacerbate image artifacts including flicker, and the appearance of unsmooth motion. To address the flicker problem, some methods repeat images multiple times before updating to new ones. This greatly reduces flicker visibility, but makes motion appear less smooth. This paper describes an investigation of how different presentation methods affect the visibility of flicker, motion artifacts, and distortions in perceived depth. It begins with an examination of these methods in the spatio-temporal frequency domain. From this examination, it describes a series of predictions for how presentation rate, object speed, simultaneity of image delivery to the two eyes, and other properties ought to affect flicker, motion artifacts, and depth distortions, and reports a series of experiments that tested these predictions. The results confirmed essentially all of the predictions. The paper concludes with a summary and series of recommendations for the best approach to minimize these undesirable effects.     

Averaging method and long-wave asymptotics in vibrational convection in layers with an interface

A scheme for applying an averaging method to the problem of convection in a two-layer system with an interface under the influence of high-frequency vibration is proposed. The derivation of the averaging equations is given, and the stability of the equilibrium of the averaged problem is considered. Long-wavelength asymptotics of steady and oscillatory instability are constructed. The results of numerical calculations for acetonitrile?Cn-hexane and silicone oil?Cfluorinert systems are given. The directions in which the investigation of thermovibrational convection in problems with free surfaces and interfaces can be continued, are indicated.     

Electrical properties of germanium-based insulator-semiconductor structures with an insulating layer of polynucleotides,and their monomer components on the surface

It is shown that adsorption of nucleic acid molecules and their monomeric components, i.e., nitrogenous bases, from aqueous solutions results in the formation of an insulating layer on the germanium surface. Comparatively small values of the insulator charge and the surface-state density point to promising applications of nucleotides for both the formation of germanium-based insulator-semiconductor structures with nanoscale insulating layers and low surface-state densities at the phase interface, and for germanium surface passivation. Changes in the electronic properties of the space-charge region of germanium during nucleotide adsorption on its surface can be used as a method for determining the nucleotide molecule concentration in aqueous solutions.     

用红光报警器闪烁显示市电停电的电路

将具有闪光报警功能的停电检测器电路(图1,参考文献1)插入电源插座中,并使用慢充电的镍镉电池。利用绿色发光二极管监视有无市电电压。BZV55-C4V3齐纳二极管D_1用于防止电池过压。来自R_6和绿色发     

Solution control of radiative and nonradiative lifetimes: a novel contribution to quantum dot blinking suppression

Time-correlated single photon counting methods are used with confocal microscopy and maximum likelihood estimation analysis to obtain fluorescence lifetime trajectories for single quantum dots with KHz update rates. This technique reveals that control of the solution environment can influence both radiative (k(rad)) and nonradiative (k(nonrad)) pathways for electron-hole recombination emission in a single quantum dot and provides a novel contribution mechanism to nearly complete suppression of quantum dot blinking, specifically by an increase in k(rad*).     

Magnetooptics of non-Kramers Eu3＋ ions in garnets： analysis complemented by crystal-field splitting modeling calculations

Spectra of absorption, luminescence, magnetic circular dichroism (MCD), and magnetic circular polarization of lumines-cence (MCPL) in Gd3Ga5O12:Eu3+and Eu3Ga5O12 garnets were studied within the visible...     

AlCrBN/AlCrSiN纳米晶多层复合涂层的制备及其性能

目的制备高硬度、高耐磨性、自润滑及高热稳定性的AlCrBN/AlCrSiN纳米晶多层复合涂层,探索涂层的微观结构、力学性能、耐磨性能及高温热稳定性能。方法采用多弧离子镀技术在WC-Co硬质合金以及不锈钢基底上,制备AlCrBN/AlCrSiN多层纳米晶复合涂层。采用扫描电子显微镜、X射线衍射、透射电子显微镜、纳米压痕仪等设备,对涂层在不同温度(600~1000℃)下退火前后的表面形貌、微观结构、力学性能、耐磨性能进行系统研究。结果AlCrSiN/AlCrBN涂层为典型的纳米晶复合多层结构,涂层主要由fcc-AlCrN纳米晶镶嵌在非晶的SiNx和BNx中并形成多层结构。涂层具有优异的热稳定性能,其结构能够保持到800℃不发生变化,当温度增加到900℃时,涂层发生调幅分解,形成c-AlN、hcp-AlN和Cr2N等复合结构,在1000℃退火后,涂层结构基本稳定,仍能检测到CrN相。涂层纳米硬度及平均摩擦因数分别为29.15 GPa和0.67。结论AlCrSiN/AlCrBN涂层具有优异的力学性能、耐磨性能及高温热稳定性能,在800℃以下保持稳定,在1000℃退火后仍能保持较高的硬度及良好的耐磨性能,在高速切削刀具中具有良好的应用前景。     

Composite control of nonlinear singularly perturbed systems via approximate feedback linearization

Machine Intelligence Research - This article is devoted to the problem of composite control design for continuous nonlinear singularly perturbed (SP) system using approximate feedback linearization...