On the processes of migration and diffusion in the systems with solid-state reagents

This paper deals with peculiarities of diffusion and migration in electrochemical systems with solid-state reagents (ESSSR). Contradictions of the diffusion model are analyzed. It is the difference of applied potentials and the corresponding electric field strength in the bulk solid phase and at the interfaces which is the primary driving force of charge transfer in ESSSR. The time characteristic of diffusion processes is not comparable to the duration of electrode processes at charging/discharging of batteries and especially electrochemical capacitors. In many real systems involving ESSSR, the process of diffusion in solid phase is absent. Examples of charge transfer processes in ESSSR (nickel hydroxide electrode, sparingly soluble quinoid compounds, Li+ intercalation in graphite, etc.) are considered, and the processes are explained using the Grothuss, tunnel and other migration mechanisms. It is shown in this paper that the linear relationship between peak currents in voltammetric curves and the square root of potential scan rate cannot be presented as an ultimate support of the diffusion model, but as а more universal property of ESSSR. In this aspect, the efficient diffusion coefficient, Deff, could be at best discussed, not to distort the ideas of charge-transfer migration mechanisms in the ESSSR

SUBSTANTIATION OF MUD PREPARATION TECHNOLOGY

To study the advantages of hydrodynamic cavitation, to calculate the frequency of cavitation oscillations by the device parameters, to obtain a formula for determining the dispersion time of the material, and to study the flow of the drilling fluid in the device using the SolidWorks program

A parallel algorithm for solving the first border value problem of elasticity theory in 3D space by Monte Carlo method

This work concerns the solution of the first border value problem of elasticity theory for 3-dimensional objects of any form and connectivity. Our approach lies in the application of random walk on spheres method for finding the solution of the differential equations system of the 6-th order which corresponds to this problem. The suggested algorithm is parallel and was designed to be run on high-performance computing clusters.Роботу присвячено розв’язанню першої крайової задачі теорії пружності для 3-вимірних тіл довільної форми та зв’язності. Наш підхід полягає у розробленні методу блукання сферами для знаходження розв’язку системи диференційних рівнянь 6-го порядку, яка відповідає цій задачі. Запропонований алгоритм є паралельним і розрахованим на виконання на високопродуктивних обчислювальних кластерах

Features of flushing an oil well

The first flushing of oil wells during drilling was carried out more than 100 years ago, when developing an oil field near the city of Grozny. Ordinary water was used as a washing liquid at that time. Currently, this technological operation is one of the main ones in the rotary drilling method. The main task of the circulation of the drilling fluid during drilling is to remove the remnants of drilled rocks, in order to avoid additional wear of the rock cutting equipment. The effectiveness of bottomhole cleaning depends on both the rate of passage of the flushing solution and its performance. That is why the flushing fluid is prepared according to established recipes and both geological (rock type, reservoir pressure, reservoir temperature, reservoir water availability, etc.) and technological factors of an oil well (depth, diameter) are necessarily taken into account during preparation

Technological schemes of acid treatments

Acid baths are the simplest acid treatments and are designed to clean the walls of the well and the bottom from the remnants of cement and clay crusts, corrosion products, resinous substances, paraffin, etc. Simple acid treatments are most often used to dissolve the contaminants introduced into the reservoir, as well as to increase the size of the pore channels by dissolving the carbonate rock

Equipment for lifting and lowering operations

The equipment of the lifting complex works in the mode of repeated short-term variable loads. The process of raising a column from a well, composed of separate sections (candles), consists of cyclones "n", which contain repeated operations in a strictly defined sequence: capture of the column by an elevator; lifting of the entire column to the length of the candle under the load on the hook, which is equal to the weight of the column wife in the solution and the resistance forces during its movement in the well; installation of the column on the rotor table; relief from the load that stretches the candle raised to the surface; loosening with keys, loosening the candle from the column with a raised candle and installing it inside the drilling rig in a special store or placing it on bridges near the drilling rig; descent of an unloaded hook and elevator for capturing a column suspended on a rotor; capturing and raising the column to the length of the next candle, etc. When descending the column, these operations are performed in the reverse sequence, but with different durations and loads

On functors associated to a simple root

Associated to a simple root of a finite-dimensional complex semisimple Lie algebra, there are several endofunctors (defined by Arkhipov, Enright, Frenkel, Irving, Jantzen, Joseph, Mathieu, Vogan and Zuckerman) on the BGG category O. We study their relations, compute cohomologies of their derived functors and describe the monoid generated by Arkhipov's and Joseph's functors and the monoid generated by Irving's functors. It turns out that the endomorphism rings of all elements in these monoids are isomorphic. We prove that the functors give rise to an action of the singular braid monoid on the bounded derived category of Oo. We also use Arkhipov's, Joseph's and Irving's functors to produce new generalized tilting modules

Methanol oxidation at platinized copper particles prepared by galvanic replacement

Bimetallic Pt-Cu particles have been prepared by galvanic replacement of Cu precursor nanoparticles, upon the treatment of the latter with a chloro-platinate acidic solution. The resulting particles, typically a few tens of nm large, were supported on high surface area carbon (Vulcan® XC–72R, Cabot) and tested as electrodes. Surface electrochemistry in deaerated acid solutions was similar to that of pure Pt, indicating the existence of a Pt shell (hence the particles are denoted as Pt(Cu)). Pt(Cu)/C supported catalysts exhibit superior carbon monoxide and methanol oxidation activity with respect to their Pt/C analogues when compared on a per electroactive surface area basis, due to the modification of Pt activity by Cu residing in the particle core. However, as a result of large particle size and agglomeration phenomena, Pt(Cu)/C are still inferior to Pt/C when compared on a mass specific activity basis