Experimental study of the effect of artificial charged aqueous aerosol cloud on model aircraft radome

The effect of artificial clouds of strongly charged aqueous aerosol on model aircraft radomes has been experimentally studied. It is established that the character of discharge development in the “charged aerosol cloud-inner electrode under model radome” gap significantly differs from that observed in the absence of the model radome. The presence of the dielectric radome in the gap between charged cloud and ground can lead to the phenomenon of reversal of the polarity of discharge current from the electrode (modeling antenna). Dependence of the discharge development and its characteristics on the size (volume) of space under radome has been studied. Possible physical mechanisms involved in the interaction of lightning discharges and thunderstorm clouds with radiotrasparent aircraft radomes and equipment arranged inside are considered.     

Breakdown of model aircraft radome dielectric shell in artificial charged aerosol clouds

The breakdown of a model aircraft radome dielectric shell in artificial charged aqueous aerosol clouds has been experimentally studied. It is established that, in most cases, electric breakdown of a model shell takes place without explicit discharge development between a charged aqueous aerosol cloud and a model antenna arranged under the radome shell. The probabilities of the dielectric shell breakdown have been determined for various radome models. A possible mechanism of the shell breakdown in hollow dielectric radomes interacting with charged aqueous aerosol clouds and electric discharges in these clouds is proposed that takes into account the accumulation of charges of opposite signs on the internal and external surface of the radome.     

Laser heating of an aqueous aerosol particle

Approximate analytical and full numerical solutions are obtained for the transient response of both a pure water and solution droplets to both short- and long-time laser heating. The differences in the temperature and size histories between pure water and solution droplets are elucidated. The validity of of the approximate analytical solution, extended from that of Armstrong ["Aerosol Heating and Vaporization by Pulsed Light Beams," Appl. Opt. 23, 148 (1984)] in pure water droplets, is evaluated by comparison to solution of the full governing equations.     

基于云模型人工鱼群算法的模糊优化设计

云模型是通过熵来控制云滴的不确定度,并利用模糊集理论中的隶属函数来判断云滴的优劣,其正向云发生器可显著提高智能优化算法的全局寻优能力.为此,采用云模型中的正向云发生器来改进人工鱼群算法(称为云模型人工鱼群算法),并将其应用于机械零部件的模糊优化设计.首先,确定模糊综合评判所需的机械零部件的相关参数,并通过模糊综合评判确...     

Vacuum discharge as an effective source of multiply charged ions

The time-of-flight (TOF) spectra measured under high vacuum conditions revealed ion beams of a cathode material (Cu ⁿ⁺) with a maximum charge of up to +19 generated in the initial stage of a spark discharge development at a storage voltage of up to U ₀=2.5 kV. As the U ₀ value increases, the range of the multiply charged states of ions detected by the TOF technique increases, the average ion charge reaching +9.     

The interaction of charged planes in an electron cloud and plasma

Distributions of the field potential, the field intensity, and the plasma density are considered for charged planes surrounded by thermoemission electrons, compensating the charge of these planes, or by a finite-density plasma. It is shown that the planes in both cases repulse each other due to the action of electrostatic forces. An expression for the electrostatic pressure is derived.     

A physical mechanism of dense smoke suppression in a closed room by admitting a charged aqueous aerosol

It is experimentally demonstrated that the rapid suppression of an optically dense aerosol (smoke) by a strongly charged aqueous aerosol is related to acceleration of the volume diffusion and to electrostatic repulsion of the charged agglomerates.     

The evolution of an aerosol cloud under conditions of diffusion mixing with gas

The one-dimensional problem of mixing of aerosol with gas, accompanied by phase transitions, is solved in a self-similar formulation. The evolution of temperature and concentration fields is studied as a function of the initial temperatures of aerosol and gas, as well as of the particle density of vapor in gas. The options are analyzed of mixing of aerosol with cold and warm gas, as well as with superheated vapor.     

Generation of aerosol nanoparticles by the multi-spark discharge generator

We have experimentally studied the formation of aerosol nanoparticles synthesized by the processes of electro-erosive wear of three pairs of electrodes upon a series connection on the discharge circuit that is controlled by a frequency generator of pulsed currents. Using a diffusion aerosol spectrometer, we have measured the particle-size distribution in the flows of aerosols upon varying velocity V of air flow, repetition frequency of discharge f, and single discharge energy W. It has been established that when controlling parameters of generator one can obtain nanoparticles (agglomerates of nanoparticles) in a wide range of mean size values d _mean from 8 to 75 nm with a geometric standard deviation (GSD) of 1.3–2.0. The growth of agglomerates of nanoparticles monotonously depends on the residence time of particles in the gas and the particle concentration.     

Simultaneous estimation of aerosol cloud concentration and spectral backscatter from multiple-wavelength lidar data

We present a sequential algorithm for estimating both concentration dependence on range and time and backscatter coefficient spectral dependence of optically thin localized atmospheric aerosols using data from rapidly tuned lidar. The range dependence of the aerosol is modeled as an expansion of the concentration in an orthonormal basis set whose coefficients carry the time dependence. Two estimators are run in parallel: a Kalman filter for the concentration range and time dependence and a maximum-likelihood estimator for the aerosol backscatter wavelength and time dependence. These two estimators exchange information continuously over the data-processing stream. The state model parameters of the Kalman filter are also estimated sequentially together with the concentration and backscatter. Lidar data collected prior to the aerosol release are used to estimate the ambient lidar return. The approach is illustrated on atmospheric backscatter long-wave infrared (CO2) lidar data.     

Effect of an electric field on the discharge of polydispersions from a slotted vertical plane-parallel channel

Results are shown of an experimental study concerning electrorheological dielectric systems and the hydrodynamic characteristics of their discharge from a slotted plane-parallel channel in the presence of a constant electric field.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 23, No. 4, pp. 681–685, October, 1972.     

Generalization of an asymptotic model for constant-rate aerosol reactors

An asymptotic model was previously developed to predictbehaviors of constant-rate aerosol reactors operating with particles in the free-molecular or continuum limits. This model considered the limiting cases of having either condensation or nucleation dominate during a nucleation burst that occurs from steady addition of condensable monomer. In the present article, this model is generalized to allow condensation and nucleation to both be important during a nucleation burst. Criteria are derived to predict the relative magnitudes of nucleation and condensation, and scaling relations are presented for particle number densities, particle sizes, and onset times and durations of nucleation bursts. Comparison of the asymptotic results with numerical integration of the governing equations is favorable both qualitatively and quantitatively.     

人工中耳力学模型的研究

依据人工中耳的机械模型[6],抽象出六条假设,并由此建立人工中耳力学模型.由变分原理及贝赛尔函数推导出人工鼓膜位移与声压的关系,得到鼓膜位移的解析解,并由此得到听骨位移.经与试验测得位移相对比,证明该方程的正确性.依据方程可以避免环境和测试人员技术水平的干扰,能够更客观地评价人工听骨的传声性能.而且该方法简单易行,同时它还可以优化听骨的材料和形状.     

Parameterization of aerosol and cirrus cloud effects on reflected sunlight spectra measured from space: application of the equivalence theorem

An original methodology to account for aerosol and cirrus cloud contributions to reflected sunlight is described. This method can be applied to the problem of retrieving greenhouse gases from satellite-observed data and is based on the equivalence theorem with further parameterization of the photon path-length probability density function (PPDF). Monte Carlo simulation was used to validate this parameterization for a vertically nonhomogeneous atmosphere including an aerosol layer and cirrus clouds. Initial approximation suggests that the PPDF depends on four parameters that can be interpreted as the effective cloud height, cloud relative reflectance, and two additional factors to account for photon path-length distribution under the cloud. We demonstrate that these parameters can be efficiently retrieved from the nadir radiance measured in the oxygen A-band and from the H(2)O-saturated area of the CO(2) 2.0 microm spectral band.     

Effect of dicationic ionic liquids on cloud points of tergitol surfactant and the formation of aqueous micellar two-phase systems

Journal of Materials Science - A cloud point evaluation was performed for the nonionic surfactant Tergitol 15-S-7 in aqueous solutions of McIlvaine buffer (pH 7.0). Cloud point temperatures of the...     

Magnetogasdynamic model of capillary discharge from evaporating wall

The article describes the mathematical and physical models of heavy-current capillary discharges. The results of numerical calculation of plasma flow in capillaries are presented.     

Theoretical investigation of colloid separation from dilute aqueous suspensions by oppositely charged granular media

A theoretical investigation of removal of colloidal particles from aqueous suspensions by oppositely charged granular (porous) media is presented in th     

Optical pulsating discharge plasma dynamics in a supersonic jet: Experiment and an analytical model of the quasistationary flow development

An analytical method for determining the wave structure and quasistationary flow parameters of an optical pulsating discharge plasma expanding in a supersonic flow is developed. The method is based on a physical model of the optical gas breakdown, a theory of the point explosion, the results of numerical modeling of the breakdown plasma dynamics along a laser beam, experimental data, and numerical estimates.     

Effect of an electrostatic field on the optical properties of a cloud of dielectric particles

The optical properties of a cloud of anisotropic dielectric particles when the orientational distribution is made nonrandom by interaction with an electrostatic field are studied. Since the interaction energy is determined by the polarizability of the particles, a general expression for the polarizability of nonspherical particles is worked out. In particular, we investigated the response to the electrostatic field of two different dispersions whose component particles are built as clusters of four identical spheres. Although in one cloud the clusters were shaped as linear chains, and in the other cloud the clusters were shaped as squares, the optical properties of both dispersions as a function of the static field are rather similar. There are, however, noticeable ranges of size within which the optical response of the two kinds of particles is substantially different.     

Calibration of the cloud and aerosol spectrometer for coal dust composition and morphology

The cloud and aerosol spectrometer (CAS) was calibrated to enable CAS sizing of coal dust for studies on flammable dust control. Coal dust sizes were determined by light-scattering theories for irregular particles that account for particle composition and morphology in computing coal dust diameters. Coal dust size computations were compared with test dust that was generated by cyclone separation and air-jet sieving and characterized by aerodynamic particle sizer (APS) and computer-controlled scanning electron microscopy (CCSEM) measurements. For test dust in the range of 0.5–32 μm, coal dust size distributions were consistent with cyclone-separated and sieve-segregated sizes. For the 3–20 μm size range, the coal dust size distribution had a mass median diameter that was 14% larger than that of the APS. This difference was reasonable considering that the basic calibration for glass spheres had 13% uncertainty. For the 20–32 μm and 32–45 μm test dusts, mass median diameters differed from CCSEM measurements by only 4% and 5%, respectively. Overall, the results suggest agreement between test dust sizes and computations for coal dust. Alternatively, using conventional Mie theory computations for spheres, coal dust mass median diameters were 35% and 40% larger than APS and CCSEM measurements, respectively.