Dependence the Integrated Energy of the Electromagnetic Response from Excitation Pulse Duration for Epoxy Samples With Sand Filler

Results of research of influence of the excitation pulse duration on the parameters of the electromagnetic response of epoxy samples with filler the quartz sand presented in the paper. The electric component of a response was registered by the capacitive sensors using a differential amplifier. Measurements were carried out at two frequencies of the master generator of 65 kHz and 74 kHz. The pulse duration was changing from 10 to 100 microseconds. The stepped sort of dependence of the integrated oscillations energy in the response from duration of the excitation pulse was discovered. The conclusion was made about the determining role of the normal oscillations in formation of such dependence

TG study of the Li[0.4]Fe[2.4]Zn[0.2]O[4] ferrite synthesis

In this paper, the kinetic analysis of Li-Zn ferrite synthesis was studied using thermogravimetry (TG) method through the simultaneous application of non-linear regression to several measurements run at different heating rates (multivariate non-linear regression). Using TG-curves obtained for the four heating rates and Netzsch Thermokinetics software package, the kinetic models with minimal adjustable parameters were selected to quantitatively describe the reaction of Li-Zn ferrite synthesis. It was shown that the experimental TG-curves clearly suggest a two-step process for the ferrite synthesis and therefore a model-fitting kinetic analysis based on multivariate non-linear regressions was conducted. The complex reaction was described by a two-step reaction scheme consisting of sequential reaction steps. It is established that the best results were obtained using the Yander three-dimensional diffusion model at the first stage and Ginstling-Bronstein model at the second step. The kinetic parameters for lithium-zinc ferrite synthesis reaction were found and discussed

Determining the effect of the duration of alternating acoustic excitation on electromagnetic response parameters of the composite

The paper presents the results of the experimental investigation dealing with the effect of the alternating excitation acoustic pulse duration on the parameters of the electromagnetic emission caused by interaction of acoustic vibrations with inhomogeneities in the sample structure, piezoelectric inclusions and media interfaces of different dielectric properties. The model sample was epoxy resin with quartz sand as filler. The electrical component of the response was recorded with a capacitive transducer. The acoustic pulse was generated by piezoelectric transducer at frequencies of 57 kHz, 65 kHz, 74 kHz, 87.5 kHz and 94.5 kHz with the pulse duration varying from 10 ?s to 100 ?s. It is shown that the reduced duration of the acoustic action leads to dominance of the intrinsic frequency in the spectrum. A contribution of tensile pulses to acoustic electromagnetic transformation response generation is revealed

Modeling of radiative - conductive heat transfer in compositing materials

A layer of composite material is investigated, which is heated one-sidedly with one-dimensional energy transfer accounting for thermal conductivity and radiation. A mathematical model is suggested for non-stationary coefficient thermophysical problem under radiative-conductive heat transfer in a material layer. Temperature dependencies of thermal capacity and thermal conductivity coefficient of composite radio-transparent material have been determined through numerical modeling by solving the coefficient reverse problem of thermal conductivity

Processing line for industrial radiation-thermal synthesis of doped lithium ferrite powders

The paper considers the issues of industrial production of doped lithium ferrite powders by radiation-thermal method. A technological scheme of the processing line is suggested. The radiation-thermal technological scheme enables production of powders with technical characteristics close to the required ones under relatively low temperature annealing conditions without intermediate mixing. The optimal conditions of the radiation-thermal synthesis are achieved isothermally under irradiation by the electron beam with energy of 2.5 MeV in the temperature range of 700-750 °С within~ 120 min

The Relationship Between the Parameters of the Electric and the Acoustic Signal with the Destruction of Concrete Under Cyclic Freeze-Thaw

The paper presents the research results of the effect of formation crack process on the parameters of the electric and acoustic response to impact excitation. The physical basis of mechanoelectric transformations is described. It was found that with increasing number of freeze-thaw cycles observed increase of the attenuation coefficient of energy of the electric and acoustic response by a linear relationship. Differences in the dynamics of change of attenuation coefficient of energy of the electric and acoustic response associated with differences in formation and registration of electric and acoustic response

Effect of ion-plasma treatment on oxidation-reduction processes in lithium-titanium-zinc ferrites

We examined the effect of nitrogen, oxygen and argon plasma on the diffusion-controlled oxidation-reduction processes in lithium-titanium-zinc ferrite ceramics by measuring the activation energy of electrical conductivity in the depth of the sample. The experimental results show that the high-temperature treatment in polycrystalline ferrites by nitrogen or argon ion plasma greatly accelerates the oxidation-reduction processes in ferrites and changes the process direction depending on the partial pressure of oxygen

THE ESTIMATION OF RISK FOR DEVELOPMENT OF DISEASES DUE TO WHOLE-BODY VIBRATION EXPOSURE IN THE WORKERS OF TURBINE SHOPS OF THERMAL POWER STATIONS

The estimation of risk for development of diseases due to whole body vibration exposure on the basis of spectral characteristics at the workplaces in turbine shops of thermal power stations was carried out. The highest average equivalent levels of whole-body vibration by speeding up of vibration and. vibration velocity were observed at the workplaces of turbine machinists of Kuznetsk Thermal Power Station and. the Western-Siberian Thermal Power Station; in the machinists-inspectors of turbine equipment the indicators were a little bit lower. At the workplaces of turbine machinists the highest levels of risk for backache in the lower part and autonomic sensory polyneuropathy syndromes development were registered at the Western-Siberian Thermal Power Station and the Southern-Kuzbass Thermal Power Station, little smaller indicators were observed at Tom-Usinsk Thermal Power Station and Kuznetsk Thermal Power Station

SPECTRAL CHARACTERISTICS OF NOISE IN THE WORKERS OF MAIN DEPARTMENTS OF THE ENTERPRISES OF ALUMINIUM AND THERMAL POWER INDUSTRIES

The study of the spectral characteristics of noise levels in the workers of main departments of the enterprises of aluminium and thermal power industries had shown that equivalent sound levels in electrolysis shops at the workplaces of those engaged in electrolysis and anodic production exceeded permissible indicators on 7,1 and 11,8 dBA; in boiler shops of a thermal power station at the workplaces of boiler machinists, machinists-inspectors of boiler equipment and mill machinists the excess in permissible indicators was 22,2 dBA, 21,4 dBA and 29,3 dBA accordingly. It was established that noise in boiler and turbine shops of a thermal power station was broadband and exceeded maximum permissible values in all parts of a spectrum. In the turbine shops of a thermal power station noise levels more often exceeded maximum permissible levels in low- and high-frequency parts of a spectrum

Strain-Magneto-Optics in Magnetostrictive Ferrite-Spinel CoFe2O4

A new direction in the physics of magnetic phenomena strain-magneto-optics based on the correlation of magnetoelastic and magneto-optical properties has been created. Experimental data are important for theoretical studies of new magneto-optical properties and the creation of functional materials.Работа выполнена в рамках государственного задания Минестерства науки и высшего образования России (тема “Спин” №АААА-А18-118020290104-2)