Clarification Of Aqueous Suspensions With A High Content Of Suspended Solids In Rapid Sand Filters

The presented work is devoted to solving the actual problem of increasing the efficiency of rapid sand filters with granular filling, which operate at a constant filtration rate when cleaning suspensions with a relatively high concentration of contaminants. The proposed mathematical model for clarifying the suspension by filtration consists of three interconnected blocks: clarified, filtration, and hydraulic. Convenient dimensionless mathematical dependencies are obtained for calculating the concentrations of contaminants and sediment from the height of the filter and suspension in the filtrate; head loss in the filter loading; the effective time of the filter (the duration of the filter cycle). The design of the experimental setup and the methodology for conducting experimental studies and mathematical processing of the results are valid. The results of experimental studies of the suspension filtering process through the granular loading are presented, and the obtained data is analyzed. Measurement of pressure losses in the filter loading is performed when a suspension is passed with a relatively high concentration of contaminants at various filtration rates. The nature of the change in the filtration rate with time and height (length) loading at various filtration rates and initial contamination concentrations is determined. Measured variable concentration of suspended matter in filtered water and retained contamination over time. As a result of the experiments, it is confirmed that an increase in the concentration of retained contaminants S leads to an increase in the parameter Δn/n. Upon reaching a certain value of the concentration of the retained sediment S (in our case S=30 g/dm3), an increase in the relative specific volume of the sediment greater than Δn/n0=0.65 is not observed. It is established that an important characteristic of the retained sediment is the ratio of the volume concentration of the sediment to the volume concentration of solid particles in this sediment γ=Csd/Сs. The values of the adhesion and detachment of particles of contaminant in the particles of the material loading =4,9; =0,009. The results of experimental studies in general confirm the correctness and reliability of the obtained analytical dependencies

Contact Displacements of Spatial Contact of a Rough Body and a Body with Coating

This paper is an example of the application of a structural nonlocal theory to the solution of the contact problem of a rough curvilinear body with plastic coating on another body. The main goal of these investigations is the creation of extrapolation methods of results of theoretical investigations from flat surfaces to any tribological system with curvilinear macro surfaces. This paper deals with the application of a phenomenological approach which is based on using the middle layer. It allows to represent a contact problem for real bodies as a superposition of two problems. The first one is the problem of penetration of rigid roughness in a plastic coating taking into account statistical characteristics of the surface. The second problem is the elastic deformation of smooth bodies with a circular area of interaction. The external load is supposed to be constant. The solution is obtained with the help of the contracting mapping principle and a simple iteration method. It is established that the first analytical approximation of solutions of the corresponding equations is useful for practical applications with sufficient accuracy. The paper deals with the case of plastic penetration of a surface asperity only when the macro contact stress is less than the yield stress of the coating, i.e. without macro plastic penetration of curvilinear bodies into this coating

Effect of Surface Rheology on Contact Displacement

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Mathematical Modelling of Spatial Contact Interaction of a System of Finite Cylindrical Bodies

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Historical legal aspects of judicial discretion

Стаття присвячена судовому розсуду як можливості суддів ухвалити рішення в кожному конкретному випадку, залежно від конкретних фактів і обставин. Судовий розсуд розглядається в історико-правовому аспекті, від часів Стародавнього Єгипту і Стародавнього Риму до початку ХХ стThe article is sanctified to judicial discretion as possibility of judges to make decision in every concrete case, depending on concrete facts and circumstances. Judicial discretion is examined in a historical legal aspect from Ancient Egypt and Ancient Rome to XX century

Controlled vortex core switching in a magnetic nanodisk by a rotating field

The switching process of the vortex core in a Permalloy nanodisk affected by a rotating magnetic field is studied theoretically. A detailed description of magnetization dynamics is obtained by micromagnetic simulations.Comment: REVTeX, 5 pages, 5 figure