Checking the adequacy of polynomial dependencies of a single-phase asynchronous motor without external phase-shifting devices for ship automation systems

Статья посвящена сравнению результатов расчётов полиномиальных зависимостей однофазного асинхронного двигателя, полученных с использованием методов планирования эксперимента, с математической моделью построенной с помощью программ на ЭВМ на языке программирования Python. Актуальность работы заключается в том, что задачи аппроксимационного типа не всегда возможно решить, используя ЭВМ, поэтому исследователи часто применяют методы планирования эксперименты для решения таких задач и после уже стоят математическую модель на ЭВМ и проверяют адекватность полученных результатов. В результате в статье авторами предоставляется план проверки адекватности полиномиальных зависимостей однофазного асинхронного электродвигателя без внешних фазосдвигающих устройств для систем судовой автоматики. По итогу выполненной работы авторы приходят к выводу об адекватности построенной математической модели на ЭВМ с использованием языка программирования Python. The article is devoted to the comparison of the results of calculations of polynomial dependencies of a single-phase asynchronous motor, obtained using methods of experiment planning, with a mathematical model built using computer programs in the Python programming language. The relevance of the work lies in the fact that problems of the approximation type are not always possible to solve using a computer, therefore, researchers often use methods of planning experiments to solve such problems and after that they already have a mathematical model on a computer and check the adequacy of the results obtained. As a result, the authors provide a plan for checking the adequacy of the polynomial dependencies of a single-phase asynchronous electric motor without external phase-shifting devices for ship automation systems. As a result of the work performed, the authors come to the conclusion about the adequacy of the constructed mathematical model on a computer using the Python programming language.

Development of a methodology for calculating and designing a single-phase asynchronous electric motor without external phase-shifting devices for ship automation systems using a mathematical model obtained using experimental planning methods

Статья посвящена разработке методики проектирования однофазного асинхронного электродвигателя без внешних фазосдвигающих устройств для систем судовой автоматики. Отмечается, что существующие на сегодняшний день известные методики расчёта микромашин не учитывает потерь в стали, что приводит к значительным погрешностям при расчёте двигателя. Авторами предлагается применять разработанную уточненную методику расчёта двигателя для дальнейшего его проектирования. Отмечается, что из выявленных в работе зависимостей важнейшей является зависимость пускового момента от электрического угла между осями обмоток 1 и 44 - α. Где выбор не оптимального электрического угла - крайне негативно сказывается на величине пускового момента однофазной микромашины. Для пояснения особенностей определения активной части двигателя авторами строится график зависимости наружной поверхности и потерь от полезной мощности. Также, в статье авторы приводят номограммы, позволяющие принимать проектировочные решения не только на основания расчёта, но и графоаналитическим методом. Результатом работы является получение новой методики расчёта и проектирования однофазной микромашины для систем судовой автоматики, используя для расчёт математическую модель, полученную с помощью методов планирования эксперимента. The article is devoted to the development of a design technique for a single-phase asynchronous electric motor without external phase-shifting devices for ship automation systems. It is noted that the currently known methods for calculating micromachines do not take into account losses in steel, which leads to significant errors in calculating the engine. The authors propose to apply the developed refined methodology for calculating the engine for its further design. It is noted that of the dependences identified in the work, the most important is the dependence of the starting torque on the electric angle between the axes of the windings 1 and 44 - α. Where the choice of a non-optimal electrical angle has an extremely negative effect on the magnitude of the starting torque of a single-phase micromachine. To clarify the features of determining the active part of the engine, the authors build a graph of the dependence of the outer surface and losses on the net power. Also, in the article, the authors provide nomograms that allow making design decisions not only on the basis of calculation, but also by the graphical analytical method. The result of the work is to obtain a new methodology for calculating and designing a single-phase micromachine for ship automation systems, using for the calculation a mathematical model obtained using experimental planning methods.

Optimization of entrapment efficiency and release of clindamycin in microsponge based gel

The aim of the present study was to formulate clindamycin (CLN) as a microsponge based gel to release the drug in a controlled manner and reduce the side effects in the treatment of acne. Since this method requires poor water solubility of the drug to be loaded in particles, therefore, conversion of the hydrochloride salt to free base was done. By using an emulsion solvent diffusion method, we made six different formulations of microsponges containing CLN-free base by changing the proportions of polymer, emulsifier and the pH of the external phase. These formulations were studied for physical characterization and for drug- polymer interactions. The physical characterization showed that microsponge formulations coded by C5, C6 resulted in a better loading efficiency and production yield and their particle size was less than 30 µm. Scanning electron microscopy images showed the microsponges porous and spherical. C5, C6 microsponge formulation was prepared as gel in Carbopol and in vitro evaluated. The microsponge formulation gel C8 was found to be optimized. C8 released 90.38% of drug over 12 h and showed viscosity 20,157 ± 38 cp, pH of 6.3 ± 0.09 and drug content of 99.64 ± 0.04%. Fourier transform infrared spectroscopy and differential scanning calorimetry confirmed no significant interactions between excipients and drug.

An Investigation on the Process of Reimbibition of Oil and Its Impact on Oil Recovery in the Yates Field

Summary In mixed- to oil-wet reservoirs characterized by intense natural fracturing where the dominant displacement mechanism is gravity drainage, surfactant injection can lead to a shift in wettability and incremental oil production. In some cases, oil can also reimbibe back into the rock matrix after the oil saturation has been reduced upon initial exposure to surfactant, suggesting limited permanence in the wettability shift. The reimbibition phenomenon is investigated in this paper using Amott cells. Three cationic surfactants (C12-, C12–16-, C16-based) with interfacial tensions (IFT) between 0.18 and 0.95 mN/m were preselected to be evaluated. Current application of the C12-based surfactant in the Yates field is considered successful based on incremental oil recovery seen during the treatment. Silurian dolomite (SD) rock samples were flooded with Yates crude oil before being aged at 60°C for 6 weeks. For the imbibition tests, the aqueous surfactant solution was set as the external phase within the Amott cell, and the recovery of oil was recorded periodically. After the imbibition tests ended, the rock samples were placed in an inverse Amott cell with the Yates oil as the external phase. Baseline tests were first conducted to show that without a surfactant in the oil or brine, no imbibition occurred. With a surfactant concentration of 3,000 ppm, oil recovery at the end of the imbibition tests varied from 34 to 60% of the original oil volume in the core sample. During the reimbibition test, a large amount of oil was able to reimbibe into the rock, displacing the brine. Most of the displacement occurred within the first 2 weeks. The net oil recovery, taken as the final volume of oil recovered in the imbibition test minus the final volume of oil reimbibed into the rock, ranged from 0 to 18%. Given the possibility of surfactant dilution in field applications, another set of tests was conducted with 1,500 ppm. A reduction in oil recovery during imbibition was observed for all the tested surfactants. Partition coefficients were determined for each of the tested surfactants, and the ion-pair mechanism was used to explain the net oil recovery results. Lastly, the impact of rock permeability on reimbibition was investigated. Results show increasing permeability may lead to a linear response in oil reimbibition; therefore, minimizing the permeability range when selecting rock samples may be necessary when conducting the reimbibition test. The importance of oil reimbibition is demonstrated in the experimental study, and we make an argument for conducting both the imbibition and reimbibition tests to better evaluate surfactant efficacy. The improved understanding of wettability alteration should lead to advancements in chemical enhanced oil recovery (EOR) designs for field treatments.

Achieving Uniform Fluid Distribution with a Custom-Designed Organic Solvent Maximizing Coiled Tubing Reach During Matrix Acid Stimulations

The success of stimulation fluid placement in openhole extended reach wells (ERWs) through coiled tubing (CT) is highly dependent on the depth achieved. Friction forces and helical buckling typically cause early CT lockup, which limits the reach. Organic deposits in the wellbore increases frictional forces causing premature lockup or in some cases even complete blockage. Efficient removal of organic deposits enables CT to reach maximum depth to perform the matrix stimulation. Analysis of these organic deposits was conducted and following a thorough comparative test, a new solvent-external phase emulsion inhibitor was selected to treat the wellbore prior to matrix stimulation. Optimum cleanout methodology was identified for the CT run with a high-pressure jetting nozzle (HPJN) combined with a chemical dissolution effect of the chosen solvent. Focused, high-energy fluid streams loosen any compacted deposits, while the high rate of fluid passing through the tool allows for an efficient cleanout. A matrix stimulation treatment with CT was then executed in the openhole section of the ERW with a TD of 18,773-ft (9800-ft horizontal lateral section) with HCl and emulsified acid systems. By using a solvent-external phase emulsion, only the external phase of the emulsion containing the dissolver is in contact with organic deposits; the remaining internal phase fluid is not. This therefore allows a reduction in total solvent volume. The proposed wellbore cleanout treatment with HPJN reduced the friction coefficient between CT and the completion by 10%. In turn, it was verified that during the operation, an additional 3,320 ft of reach was achieved in the openhole section. Combined with other extended-reach techniques (i.e., mechanical agitator tools, friction reducers), it allowed the 2.0-in CT pipe to reach the TD of the well (18,773 ft). These efforts together maximized the reservoir contact during the matrix stimulation in the openhole section with HCl and emulsified acid systems. Distributed temperature sensing (DTS) methodology was used with the aid of fiber optic installed CT, and the intake profile of the openhole section was mapped. Analysis of the data was applied to optimize the pumping schedule to obtain uniform production contribution across the openhole section. The systematic engineering workflow presented includes the organic deposit diagnostic procedure, laboratory testing, chemical selection, and treatment application. This yields a wellbore treatment that minimizes friction for the remainder of the operation and enables maximum CT reach. This provides more insights of integrated matrix stimulation treatment with CT to overcome the serious challenges present in extended reach openhole wells.

An Investigation on the Process of Re-Imbibition of Oil and its Impact on Oil Recovery in the Yates Field

In mixed- to oil-wet reservoirs characterized by intense natural fracturing where the dominant displacement mechanism is gravity drainage, surfactant injection can lead to a shift in wettability and incremental oil production. In some cases, oil can also re-imbibe back into the rock matrix after the oil saturation has been reduced upon initial exposure to surfactant, suggesting limited permanence in the wettability shift. The re-imbibition phenomenon is investigated in this paper utilizing Amott cells. Three cationic surfactants (C12-, C12-16-, C16-based) solutions with interfacial tensions (IFT) between 0.18 to 0.95 mN/m were pre-selected to be evaluated. Current applications of the C12- based surfactant in the Yates field is considered successful based on incremental oil recovery seen during the treatment. Silurian dolomite rock samples were flooded with Yates crude oil before being aged at 140 °F for 6 weeks. For the imbibition tests, synthetic brine was set as the external phase within the Amott cell and the recovery of oil was recorded periodically. After the imbibition tests ended, the rock samples were placed in an inverse Amott cell with the Yates oil as the external phase. Baseline tests were first conducted to show that without a surfactant in the oil or brine, no imbibition occurred. With a surfactant concentration of 3,000 ppm, oil recovery at the end of the imbibition tests varied from 34% to 64% of the original oil volume in the core sample. During the re-imbibition test, a large amount of oil was able to re-imbibe into the rock, displacing the brine. Most of the displacement occurred within the first two weeks. The net oil recovery, taken as the final volume of oil recovered in the imbibition test minus the final volume of oil re-imbibed into the rock, ranged from 0% to 18%. Given the possibility of surfactant dilution in field applications, another set of tests were conducted with 1,500 ppm. A reduction in oil recovery during imbibition was observed for both the C12- based surfactant and the C12-16- mixture. Partition coefficients were determined for each of the tested surfactants and the ion pair mechanism was used to explain the net oil recovery results. Lastly, the impact of rock permeability on re-imbibition was investigated. Results show increasing permeability may lead to a linear response in oil re-imbibition,therefore minimizing the permeability range when selecting rock samples may be necessary when conducting the re-imbibition test. The importance of oil re-imbibition is demonstrated in the experimental study and we make an argument for conducting both the imbibition and re-imbibition tests to better evaluate surfactant efficacy. The improved understanding of wettability alteration should lead to advancements in chemical enhanced oil recovery designs for field treatments.

NANOEMULSION FOR TOPICAL THERAPY OF ACNE: OPTIMIZATION AND EVALUATION

The present investigation was aimed / carried out to develop a nano-sized emulsion-based vehicle containing 13-cis-retinoic acid as a means of increasing its permeability and be a suitable topical therapy for acne. Various heterogeneous dispersions were formulated by spontaneous nano emulsification method using 9% w/w propylene glycol dicaprylate/dicaprate, 27% w/w caprylocaproyl macrogol glycerides, 9% w/w polyglyceryl–6–dioleate and 55% w/w distilled water as an external phase. All plain and 13- cis-retinoic acid loaded nanoemulsions were clear and showed suitable physicochemical parameters for desired topical delivery and stability. The permeation profiles of 13-cis-retinoic acid through rat skin from selected optimized nanoemulsion formulation followed zero order kinetics. The microscopic observations indicate that the optimized nanoemulsion has no significant effect on the microscopic structure of the skin and epithelial cells appeared mostly unchanged. The surface epithelium lining and the granular cellular structure of the skin were totally intact. Hence, developed nanoemulsion containing 13-cis-retinoic acid would be a potential drug delivery vehicle for effective management of acne.

Biocompatible Solvents and Ionic Liquid-Based Surfactants as Sustainable Components to Formulate Environmentally Friendly Organized Systems

In this review, we deal with the formation and application of biocompatible water-in-oil microemulsions commonly known as reverse micelles (RMs). These RMs are extremely important to facilitate the dissolution of hydrophilic and hydrophobic compounds for biocompatibility in applications in drug delivery, food science, and nanomedicine. The combination of two wisely chosen types of compounds such as biocompatible non-polar solvents and ionic liquids (ILs) with amphiphilic character (surface-active ionic liquids, SAILs) can be used to generate organized systems that perfectly align with the Green Chemistry concepts. Thus, we describe the current state of SAILs (protic and aprotic) to prepare RMs using non-polar but safe solvents such as esters derived from fatty acids, among others. Moreover, the use of the biocompatible solvents as the external phase in RMs and microemulsions/nanoemulsions with the other commonly used biocompatible surfactants is detailed showing the diversity of preparations and important applications. As shown by multiple examples, the properties of the RMs can be modified by changes in the type of surfactant and/or external solvents but a key fact to note is that all these modifications generate novel systems with dissimilar properties. These interesting properties cannot be anticipated or extrapolated, and deep analysis is always required. Finally, the works presented provide valuable information about the use of biocompatible RMs, making them a green and promising alternative toward efficient and sustainable chemistry.