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

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

Research into the process of preparation of Ukrainian coal by the oil aggregation method

We conducted a study into concentration of Donetsk coal with varying degrees of coalification – anthracite and grade G – by the method of oil aggregation. We determined the character of impact of the following factors on the results of oil aggregation of coal: the ash content of original coal, pulp agitation duration, pulp density, consumption and type of reagent-binder. The research demonstrated a possibility of effective preparation of finely- and thinly dispersed Donetsk coal the size of 0–0.1; 0–1(2) mm and ash content from 10–15 % to 65–70 % by the method of oil aggregation. In this case, it was established that with an increase in the ash content of original coal, the process of oil aggregation displays a capacity of self-leveling. By reducing the speed of aggregation, it is possible to attain practically stable technological results over the entire examined range of ash content of original coal – from 10–15 % to 65–70 %. Obtained results substantiate the possibility of employing the process of oil aggregation for the re-preparation of waste, in particular, waste of flotation and gravitation separation of coal preparation.Досліджено збагачення донецького вугілля різного ступеня вуглефікації масляною агрегацією. Встановлено вплив на результати процесу зольності вугілля, тривалості агітації, густини пульпи, витрат і виду реагенту. Показано можливість ефективного збагачення вугілля крупності 0–0,1 (2) мм, зольності 10–70 % і самовирівнювання масляної агрегації при збільшенні зольності. Обгрунтовано застосування масляної агрегації для перезбагачення відходів флотації

Research into the process of preparation of Ukrainian coal by the oil aggregation method

We conducted a study into concentration of Donetsk coal with varying degrees of coalification – anthracite and grade G – by the method of oil aggregation. We determined the character of impact of the following factors on the results of oil aggregation of coal: the ash content of original coal, pulp agitation duration, pulp density, consumption and type of reagent-binder. The research demonstrated a possibility of effective preparation of finely- and thinly dispersed Donetsk coal the size of 0–0.1; 0–1(2) mm and ash content from 10–15 % to 65–70 % by the method of oil aggregation. In this case, it was established that with an increase in the ash content of original coal, the process of oil aggregation displays a capacity of self-leveling. By reducing the speed of aggregation, it is possible to attain practically stable technological results over the entire examined range of ash content of original coal – from 10–15 % to 65–70 %. Obtained results substantiate the possibility of employing the process of oil aggregation for the re-preparation of waste, in particular, waste of flotation and gravitation separation of coal preparation.Досліджено збагачення донецького вугілля різного ступеня вуглефікації масляною агрегацією. Встановлено вплив на результати процесу зольності вугілля, тривалості агітації, густини пульпи, витрат і виду реагенту. Показано можливість ефективного збагачення вугілля крупності 0–0,1 (2) мм, зольності 10–70 % і самовирівнювання масляної агрегації при збільшенні зольності. Обгрунтовано застосування масляної агрегації для перезбагачення відходів флотації

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

Use of Simulation Methods of Wave Processes for Non-Destructive Testing of Concrete Products of Different Geometrical Size

Theoretical and experimental research of electrical responses under pulsed mechanical excitation of different size concrete products was carried out. Comparison of calculated and experimental data shows very close agreement. The obtained results will help to develop new opportunities to improve the method of non-destructive testing of concrete by creating a bank of calculated electrical responses from products of different geometrical arrangement and elastic response and using them as standard samples for defectiveness evaluation of products according to previously established criteria

Benchmark Calculations of Electron Impact Electronic Excitation of the Hydrogen Molecule

We present benchmark integrated and differential cross-sections for electron collisions with H$_2$ using two different theoretical approaches, namely, the R-matrix and molecular convergent close-coupling (MCCC). This is similar to comparative studies conducted on electron-atom collisions for H, He and Mg. Electron impact excitation to the $b \ ^3\Sigma_u^+$, $a \ ^3\Sigma_g^+$, $B \ ^1\Sigma_u^+$,$c \ ^3\Pi_u$,$EF \ ^1\Sigma_g^+$,$C \ ^1\Pi_u$,$e \ ^3\Sigma_u^+$,$h \ ^3\Sigma_g^+$,$B' \ ^1\Sigma_u^+$and$d \ ^3\Pi_u$excited electronic states are considered. Calculations are presented in both the fixed nuclei and adiabatic nuclei approximations, where the latter is shown only for the$b \ ^3\Sigma_u^+$ state. Good agreement is found for all transitions presented. Where available, we compare with existing experimental and recommended data.Comment: 21 pages, 25 figure

Close-coupling approach to antiproton-impact ionisation of H2 with analytical spherical averaging

Integrated cross section for single ionisation of molecular hydrogen by antiproton impact has been calculated in a wide range of impact energies from 1 keV up to 2 MeV using a close-coupling approach. For the first time all possible orientations of the molecular target have been accounted for using an ab initio analytical spherical averaging technique. Obtained results are in good agreement with experiment

EFFECT OF THE SIZE OF COARSE AGGREGATE IN CONCRETE ON THE PARAMETERS OF THE ELECTRIC RESPONSE

The parameters of the electric response to the elastic impact excitation of heavy concrete samples with different size of coarse aggregate were studied. It is shown that the change of the aggregate size leads to a change of power, amplitude-time and amplitudefrequency characteristics of the electric response.Работа выполнена в рамках Государственного задания «Наука»

Positron scattering on atoms and molecules

An overview is given of recent progress in the calculation of positron scattering on atoms and molecules using the convergent close-coupling method. Particular emphasis is given to those cases where positronium formation is one of the reaction channels, as well as the importance of demonstrating convergence with increasing orbital angular momentum of the bases used. Targets considered are atomic hydrogen, lithium, and molecular hydrogen