This paper presents the results of the evolution of the structure of filtration films of the MFFC-3 and PP-190 types in the process of purification of ethereal substances. It has been established by ...thermogravimetry that a decrease in the mass of samples of working films for MFPC-3 by ~22%, and for PP-190 by 18%, which is a at temperatures of ~130–265°C, is due to the destruction of the polymer molecules of the drainage layer as a result of transmembrane pressure and diffusion of ethereal substances. For a pure MFFC-3 membrane sample, a single thermal effect is recorded at the peak melting temperature
T
max
= 247°С, typical for lavsan with melting enthalpy Δ
H
= 40 kJ/kg, and for the working sample at
T
max
= 249°C with Δ
H
= 19 kJ/kg. For a clean sample of the pre-filter PP-190, a single thermal effect is recorded at the peak melting temperature
T
max
= 160°C with Δ
H
= 68 kJ/kg, and for the working sample at
T
max
= 157°C with Δ
H
= 67 kJ/kg. The bulk crystallinity of the MFFC-3 and PP-190 films of the working samples decreased by 52 and 33%, respectively, in relation to the initial ones, according to the data of differential scanning calorimetry. X-ray diffraction data indicate changes in the microstructure of films of working samples in the intergranular amorphous phase as a result of deformation of lamellar crystallites, while the X-ray degree of crystallinity of the MFPC-3 film decreased by 12%, and that of PP-190 by 9%. On the dependence curves of the hydrodynamic permeability of MFFC-3 and PP-190 filtration films on time at different transmembrane pressures, four characteristic periods are noted, where gel clots are formed on the MFFC-3 membrane, which significantly affect the process of baromembrane separation and the PP-190 pre-filter becomes clogged.
Uncooled photodiodes based on GaSb/GaAlAsSb heterostructures for recording pulsed infrared radiation in the spectral range of 0.9–1.8 μm are developed and studied. The GaSb active region is prepared ...using lead as a neutral solvent in order to reduce the concentration of natural acceptors. The capacitance of the photodiodes with a sensitive-area diameter of 300 μm is 115–135 pF without bias and 62–70 pF with a reverse bias of 1.5 V. The response speed of the photodiode measured in the photovoltaic mode using an InGaAsP/InP laser with a radiation wavelength of 1.55 μm is as high as τ
0.1–0.9
= 42–60 ns. It is demonstrated experimentally that the fabricated photodiodes can be used without cooling to detect pulsed laser and LED radiation in the near-IR spectral region.
The problem of biofuel purification using microfiltration and prefiltration at various transmembrane pressures is considered. The scheme of an experimental installation for carrying out the ...microfiltration process is presented. One of the main elements of the installation is a flat-chamber type working cell, the design of which is described in detail. For the implementation of membrane purification, working samples of MFFK-3 microfiltration membrane and PP-190 preliminary filter manufactured by Research and Production Enterprise Technofilter (Vladimir, Russia) are selected. The kinetic dependences of the specific outlet flow for the MFFK-3 and PP-190 porous films are obtained as a function of time at various transmembrane pressures. The dependences show four periods of change in the specific outlet flow, where gel clots are formed on the MFFK-3 membrane and the PP-190 filter. The dependences of the water content in the filtrate on the transmembrane pressure are given. To separate water from the E phase, it is necessary to maintain a pressure in the baromembrane system of at least 0.5 MPa. Electron microscopic studies of the initial and working samples of MFFK-3 and PP-190 porous films are carried out. Chromatographic analysis of the permeate and concentrate after microfiltration purification show that such components as methanol, margarine oleic, oleic, behenic, erucic, and docosadienoic acids pass through the membrane partition forming a dynamic gel layer on the surface, which prevents the passage of water molecules.
Laboratory stand for car tire diagnostics Holshev, N. V.; Konovalov, D. N.; Prokhorov, A. V. ...
Vestnik SibADI (Online),
01/2022, Letnik:
18, Številka:
6
Journal Article
Recenzirano
Odprti dostop
Introduction.
An automobile vehicle consists of a large number of parts that affect traffic safety in different ways.
The elements that critically affect the safety of the vehicle include automobile ...pneumatic tires. Their technical
condition is currently being assessed visually, without the use of special equipment. This diagnostic method does
not provide detection of hidden tire damage. This article describes the proposed method of diagnosing pneumatic
tires of passenger cars, as well as the scheme of the stand for its implementation.
Materials and methods.
Based on previous studies, it was proposed to use the static stiffness of automobile
tires as a diagnostic parameter when assessing their technical condition. To implement the use of this diagnostic
parameter, a new method for assessing the technical condition of tires was proposed. It consists in determining
and comparing the values of the static stiffness of the tire at its various points with the average stiffness value at all
measurement points. To implement this method in the laboratory, a schematic diagram of the stand was proposed.
Results.
In accordance with the proposed scheme of the stand, a volumetric model of the stand was developed
for the implementation of the proposed method in laboratory conditions, and the frame of the stand was made
and its main elements were selected. As a converter of the rotational movements of the potentiometer handle
into the electronic signal, it was decided to use the Arduino Uno R3 analog-to-digital converter. Software was also
developed to automate the reading and processing of bus diagnostic results.
Discussion and conclusions.
The proposed method of tire diagnostics and the stand implementing it can increase
the efficiency and simplicity of assessing the technical condition of pneumatic tires of passenger cars. Further
research is needed to assess the effectiveness of the proposed solutions.
The effect of the transmembrane pressure and diffusion of essential substances on the transformation of the structure in polymer membranes of UPM-100 and PP-190 type is studied in this work. It is ...found by thermal methods that the processes of reduction of the weight of the samples of the working films by about 15% for PP-190 and 13% for UPM-100 that are observed at 160–220°C are determined by the destruction of the polymer molecules of the drainage layer. The analysis of the TG and DSC curves of the initial and working samples of the films of UPM-100 and PP-190 makes it possible to note that the transmembrane pressure and diffusion of essential substances mainly induce destruction of the molecules of the amorphous phase of the drainage layer with an insignificant decrease in the crystallinity of the polymer matrix. X-ray structural studies reveal that, in a UPM-100 composite film, transmembrane pressure initiates the conformation of the crystallites of the polymer PETF matrix with the orientation of the (
a
) and (
b
) crystallographic axes at a certain angle to the surface of the film, as well as of the macromolecule chains parallel to the surface of the film. Comparisons of the data of X-ray diffraction analysis show that substantial changes in the microstructure of the samples of the working films occur in the intercrystalline amorphous phase as a result of the conformation of the lamellar crystallites; here, the degrees of crystallinity of the polymer PP and PETF matrices decrease by ~10%.
A tubular electrobaric membrane system is developed for processing of solutions in manufacturing and the chemical industry. An optimized system with increased effective area for separation of the ...solutions is proposed; its volume and mass are calculated. Besides increasing the effective area for separation of the solutions, the proposed system increases the quality of separation and the productivity; and decreases the materials consumed per unit volume.
Results of the structure evolution in MFFK-3 and PP-190 polymer films during the purification of water–organic solutions are described. X-ray diffraction analysis data show that significant changes ...in the microstructure of the working film samples occur in the intergranular amorphous phase due to the conformation of lamellar crystallites; in this case, the percentage of crystallinity of the MFFK-3 and PP-190 films decreases by 22 and 9%, respectively. Electron microscopy studies of the original and working samples of the MFFK-3 microfiltration membrane and the PP-190 prefilter on a JEOL JSM 6510 electron microscope at a magnification of 140–7000× are described. For the original and working samples of the MFFK-3 microfiltration membrane and the PP-190 prefilter, it is found that organic substances present in the feed solution are adsorbed on the surface of the active layer of the films.
In this work, experimental data on the rejection coefficient and the specific output flux are obtained. Based on the studies, graphical dependencies of the rejection coefficient on the specific ...output flux were constructed and analyzed. During the analysis, it was noted that with an increase in the output specific flow of the solvent, the rejection coefficient decreases. The reason for this is the boundary layers of fat and protein formed in the near-membrane layers, which prevents the passage of protein molecules through the pores of the membrane. For the theoretical calculation of the rejection coefficient and specific output flux, mathematical expressions are developed and numerical values of the values of empirical coefficients are obtained. The developed mathematical expressions describe the experimental data with good confidence. The obtained experimental and calculated data can be used with great reliability in the calculations of mass-transported flows of substances through semipermeable membranes, as well as in engineering methods for calculating and predicting the effectiveness of the use of membrane processes for the concentration of whey.
A design is proposed for an electrobaric membrane system of coil type for use in the separation of solutions. The effective total working area of the membranes is calculated. The volume of solution ...that may be separated by the refined system here proposed is compared with that for the prototype system (described in the literature).
A theoretical formalism for quantitative description of X-ray diffraction from Langmuir monolayers under conditions of total external reflection has been developed. The proposed approach, based on ...the distorted-wave approximation, allows to consider physical mechanisms for plotting diffraction curves and maps (in the reciprocal space) for real monolayers and describe self-consistently specific features of Bragg peaks. The resulting algorithm can easily be implemented on a personal computer, which provides the opportunities to carry out numerical simulation of experimental two-dimensional diffraction intensity maps and determine reliably both the mean values of structural parameters of layers and their rms deviations.
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