Modification of the RLA model for presenting a cluster system of a composite material with a fractal filler structure

The paper proposes a modification of the diffusion-limited aggregation model to study the properties of a cluster system. A computational experiment to determine the mutual influence of the sticking probability and the volume concentration of particles on the formation of fractal clusters in a cluster system was carried out in accordance with the second-order orthogonal central compositional plan (OCCP). As a result of a computational experiment in accordance with the OCCP, an equation was obtained for the dependence of the mass fractal dimension of clusters on the volume of particle concentration and the probability of adhesion of diffusing particles and cluster particles in the adhesion zone. This dependence was obtained in a range of volume concentration of particles from 2 to 5 % and the probability of adhesion of diffusing particles and particles of clusters in the adhesion zone from 0.2 to 1.

Электронная структура вариантов составов скандатных и оксидно-никелевых катодов СВЧ приборов

By methods of electron spectroscopy for chemical analysis and spectroscopy of characteristic losses of electron energy, the electronic structure of barium oxide crystallites doped with other chemical elements, including scandium from scandium-containing phases, was investigated. The physical and physicochemical conditions are formulated, the fulfillment of which allows to form the electronic structure of the scandate cathode with a high level of thermionic emission: the achievement of the minimum ratio of the surface volume concentration of oxygen vacancies and the maximum distance between the top of the valence band and the Fermi level.

Rheological Properties of TiO2/POE Nanolubricant for Automotive Air-Conditioning System

The enhancement of nanolubricant rheological properties can improve the performance of automotive air-conditioning systems. The rheological properties of the TiO2/POE nanolubricant were investigated in this study at 0.01 to 0.1% volume concentrations and temperatures ranging from 0 to 100°C. TiO2 nanoparticles were dispersed in the base lubricant of Polyol-ester (POE RL68H) lubricant in two steps. The dynamic viscosity was measured with an Anton-Paar Rotational Rheometer. According to the findings, the TiO2/POE nanolubricant behaved as Newtonian fluids at all volume concentrations and temperatures. The dynamic viscosity increment of nanolubricants up to 1.75% only occurred for 0.1% volume concentration and temperature of 90 to 100°C. Meanwhile, when compared to POE lubricant, nanolubricants with volume concentrations of 0.01 and 0.05% showed a decrement trend in dynamic viscosity of up to 1.8%. Finally, the TiO2/POE nanolubricant improved the rheological properties of the POE lubricant for use in automotive air-conditioning systems.

Investigation on Rheological Properties of Water-Based Novel Ternary Hybrid Nanofluids Using Experimental and Taguchi Method

This study presents the rheological behavior of water-based GO-TiO2-Ag and rGO-TiO2-Ag ternary-hybrid nanofluids. The impact of nanoparticles’ volumetric concentration and temperature on the rheological properties were studied. All experiments were performed under temperatures ranging from 25 to 50 °C in the solid volume concentration range of 0.5–0.00005%. The data optimization technique was adopted using the Taguchi method. The types of nanomaterials, concentration, temperature, and shear rate were chosen to optimize the viscosity and shear stress. The effect of shear stress, angular sweep, frequency sweep, and damping factor ratio is plotted. The experimental results demonstrated that the rheological properties of the ternary hybrid nanofluid depend on the ternary hybrid nanofluid’s temperature. The viscosity of ternary hybrid nanofluids (THNf) change by 40% for GO-TiO2-Ag and 33% for rGO-TiO2-Ag when temperature and shear rates are increased. All the ternary hybrid nanofluids demonstrated non-Newtonian behavior at lower concentrations and higher shear stress, suggesting a potential influence of nanoparticle aggregation on the viscosity. The dynamic viscosity of ternary hybrid nanofluid increased with enhancing solid particles’ volume concentration and temperature.

Measurement of Dielectric and Magnetic Constants of Ferrofluid-Doped Sol-Gels by a Resonant Cavity Method

Materials with specific electromagnetic properties are increasingly used for the realization of passive components. Therefore, electromagnetic characterization is a priority to know these materials properties. This study focuses on the electromagnetic characterization of 10 nm maghemite ferrofluid doped sol-gel using a resonant cavity method. We deposited the sol-gel by dipping/removal on an alumina substrate in order to make measurements on the cavity to determine the complex permittivity and permeability. Two studies were carried out; the first consisted in varying the doped sol-gel thickness of layers of the same concentration in the realization of samples; and the second consisted in varying the volume concentration of ferrofluid according to the matrix dimensions. The first study showed that the dielectric constants do not vary with the thickness of the magnetic sol-gel layers. In the second study, measurements also showed that the gyromagnetic resonance is the same for all samples regardless of the ferrofluid volume concentration.

Impact of Microplastics on Oil Dispersion Efficiency in the Marine Environment

Oil spill and microplastics (MPs) pollution has raised global concerns, due to the negative impacts on ocean sustainability. Chemical dispersants were widely adopted as oil-spill-treating agents. When MPs exist during oil dispersion, MP/oil-dispersant agglomerates (MODAs) are observed. This study explored how MPs affect oil-dispersion efficiency in oceans. Results showed that, under dispersant-to-oil volumetric ratio (DOR) 1:10 and mixing energy of 200 rpm, the addition of MPs increased the oil droplet size, total oil volume concentration, and oil-dispersion efficiency. Under DOR 1:25 and mixing energy of 120 rpm, the addition of MPs increased the oil droplet size but resulted in a decrease of total oil volume concentration and dispersion efficiency. Compared with the oil volume concentration, the oil droplet size may no longer be an efficient parameter for evaluating oil-dispersion efficiency with the existence of MODAs. A machine learning (ML)-based XGBRegressor model was further constructed to predict how MPs affected oil volume concentration and oil-dispersion efficiency in oceans. The research outputs would facilitate decision-making during oil-spill responses and build a foundation for the risk assessment of oil and MP co-contaminants that is essential for maintaining ocean sustainability.

Comparative analysis of the theory of constrained sedimentation and compression of sediments

The object of research contains a comparison between the theories made by Kynch and professor E.F. Kurgaev. These theories are based on the fundamental hypothesis about the change in volume concentration during compression (settling). The features of both of them have been clarified to be applied to the study of sediments compression from stations of potable water preparation. The advantage of the theory of professor E.F. Kurgaev considers the term of sediments compression both in short term and long term perspective, meaning up to several years, which is especially important for the calculation of sludge collectors.

Laboratory studies of suspended particle volume concentration in atmosphere using a smartphone

The article presents the results of laboratory studies of the effect of volume concentration of suspended particles in contrast to the luminous slits image obtained by smartphone cameras of SAMSUNG Galaxy A3 and Honor 8 Lite. Experimentally it was found that a pattern of change in contrast to the luminous slits image from the volumetric concentration of suspended particles appears under ambient light. The pattern of contrast change can be expressed by an exponential function. The correlation coefficient is 0.97. Cigarette smoke was used as suspended particles.

Operation of marine diesel on biodiesel

Annotation – The influence of biodiesel fuel on the economic and ecological performance of the marine diesel engine is considered. The reasons limiting use of alternative fuels (including fuels based on biological origin) on vessels are indicated. The results are performed on a specialized vessel with a deadweight of 10,820 tons, which carried out short-term (within 4 ... 6 days) transitions between ports, were it was possible to replenish alternative fuel stocks. Studies performed on 5DC-17A Tier II Daihatsu Diesel marine diesels in the range of their operational loads 55 ... 85 %, from a fuel mixture consisting of 80 ... 95% of DMB diesel fuel and 5 ... 20% of B99.9 FAME biofuel, next conclusion have been done: in all range of loads and for all content of biofuels in the fuel mixture there is an increase in the specific efficient fuel consumption; on the operating modes in range 55 ... 65% of nominal loading and 5 ... 10 % of the maintenance of biofuel in mix this increase makes 1.92 ... 2.96 %, on the modes 75 ... 85 % of loading and at use mixtures with a content of 15 ... 20 % biofuels increase in fuel consumption reaches 4.04 ... 6.67 %; most of all, the efficiency of the diesel engine detected during its operation at loads of 55 ... 65 % and 15 ... 20 % of the biofuel content in the mixture, in this conditions, the increase in specific fuel efficiency reaches 7.39 ... 8.17 %; during the operation of the diesel engine in the load range of 55 ... 85 %, the emission of nitrogen oxides is observed, with best efficacies (up to 23.8 ... 24.3 %) corresponding to 10 ... 15 % of the biofuel content in mixtures; with an increase in the content of biofuels in the mixture up to 20 % reduction in emissions of nitrogen oxides is in the range of 10.1 ... 15.2 %; the use of biofuels helps to reduce the volume concentration of carbon monoxide in the exhaust gases; the greatest efficiency is corresponding at load 75 ... 85 % and use of the fuel mix containing 20 % of biofuel, under such conditions decrease in concentration of carbon monoxide reaches 25.4%; which further enhances the energy efficiency of ships. The optimal composition of the fuel mixture containing biofuel has been proposed, taking into account its environmental (before the emission of nitrogen oxides and the volume concentration of carbon monoxide in the exhaust gases), as well as economic performance of marine diesel.