НАГРУЖЕНИЕ ГРУНТА ТРАКАМИ ГУСЕНИЧНЫХ МАШИН: ОБЗОР РАСЧЕТНЫХ СХЕМ

The results of investigations in the field of existing soil loading schemes by tracks of tracked vehicles and their effect on the traction force realized by a caterpillar propulsion device are presented. The review shows that most researchers emphasize the important role of lugs in the creation of tractive effort. However, most of the existing methods of calculating the traction force on the clutch are based on one or another specific design scheme that does not depend on the loads acting on the tracks, on the combination of the parameters of the grousers and on the physical and mechanical properties of the soil. The use of these methods does not allow us to consider the sequence and alternative variants of soil disruption, and also to establish a relationship between the magnitude of the tangential force acting on the tract with a wide range of combinations of geometric parameters of the grousers, and to link it to the physical processes taking place in the soil. Consequently, these methods do not fully describe the interaction of the crawler tracks with the ground, which makes it difficult to use them to optimize the geometric parameters of the lugs. The authors proposed an analytical method for analyzing the interaction of soil with a track of a caterpillar engine based on the regularities of the theory of the limiting state of ground masses and the main provisions used in the theory of cutting soil, taking into account the revealed features of this interaction, which makes it possible to investigate the interaction of tracks of a caterpillar propulsion with soil, taking into account the multiphase and alternative options for the destruction of soil between the grousers. This method allows you to choose the parameters of the lugs, providing an improvement in traction and coupling properties of crawler tractors. Приведены результаты исследований в области существующих схем нагружения грунта траками гусеничных машин и их влияния на реализуемую гусеничным движителем силу тяги по сцеплению. Проведенный обзор показывает, что большинство исследователей подчеркивают немаловажную роль грунтозацепов в создании тягового усилия. Однако большая часть существующих методов расчета силы тяги по сцеплению базируется на определенной расчетной схеме, не зависящей от нагрузок, действующих на траки, от сочетания параметров грунтозацепов и от физико-механических свойств грунта. Использование этих методов не позволяет рассмотреть последовательность и альтернативные варианты разрушения грунта, а также установить взаимосвязь величины касательной силы, действующей на трак, с широким спектром сочетаний геометрических параметров грунтозацепов и связать ее с физическими процессами, протекающими в грунте. Следовательно, эти методы не в полной мере описывают взаи- модействие грунтозацепов гусеничного движителя с грунтом, что затрудняет их использование для оптимизации геометрических параметров грунтозацепов. Авторами предложен аналитический метод анализа взаимодействия грунта с траком гусеничного движителя, основанный на закономерностях теории предельного состояния грунтовых масс и основных положений, используемых в теории резания грунта, учитывающий выявленные особенности этого взаимодействия. Данный метод позволяет проводить исследование взаимодействия траков гусеничного движителя с грунтом с учетом многофазности и альтернативных вариантов разрушения грунта, находящегося между грунтозацепами, а также выбирать параметры грунтозацепов, которые обеспечивают улучшение тягово-сцепных качеств гусеничных тягачей

Hierarchically Porous Carbon Cloth–Polyaniline (CC–PANI) Composite Supercapacitor Electrodes with Enhanced Stability

In this work, hierarchically porous composites were prepared in the form of activated carbon cloth (CC) Busofit T–1–055 filled with an electrically conductive polymer, polyaniline (PANI), for use as pseudocapacitive electrodes of electrochemical supercapacitors (SCs). CC fibers have high nanoporosity and specific surface area, so it was possible to deposit (via the chemical oxidative polymerization of aniline) a significant amount of PANI on them in the form of a thin layer mainly located on the inner surface of the pores. Such morphology of the composite made allowed the combining of the high capacitive characteristics of PANI with the reversibility of electrochemical processes, high columbic efficiency and cyclic stability rather typical for carbon materials of double-layer SCs. The highest capacitance of composite electrodes of about 4.54 F/cm2 with high cyclic stability (no more than 8% of capacity loss after 2000 charge–discharge cycles with a current density of 10 A/cm2) and columbic efficiency (up to 98%) was achieved in 3 M H2SO4 electrolyte solution when PANI was synthesized from an aniline hydrochloride solution with a concentration of 0.25 M. Trasatti analysis revealed that 27% of specific capacitance corresponded to pseudocapacitance, and 73% to the double-layer capacitance

Dural arteriovenous fistulas: two case reports and review

The paper discusses the etiology, pathogenesis, classification, principles of diagnosis and tactics of surgical treatment of dural arteriovenous fistulas. The study presents two case reports of successful treatment of patients with symptomatic dural arteriovenous fistulas

The place of 3D modeling in the educational space

При организации учебного процесса необходимо учитывать быстроразвивающиеся цифровые возможности. Огромным потенциалом в развитии творческих навыков, критического мышления обладает 3D-моделирование. Практикующим инженерам в современной реальности необходимо генерировать новые идеи и предлагать инновационные решения. Учащиеся через практический опыт, через технологии 3D-печати, могут понять, в чем заключается современная инженерная деятельность.It is necessary to take into account the rapidly developing digital opportunities to organize the educational process. 3D modeling has a huge potential in developing creative skills and critical thinking. Practicing engineers need to generate new ideas and offer innovative solutions in modern reality. Students can understand what modern engineering activities are through 3D printing technologies, through practical experience

Stent-assisted coiling of acute ruptured cerebral aneurysms

The necessity of quick surgical treatment of acute ruptured cerebral aneurysms was demonstrated in large studies by the ISAT and ISUIA, which also proved the advantage of the endovascular method over the surgical one. Ballonassistence is widely used in treatment of aneurysms with wide neck and unfavorable vascular anatomy, but the radicality of the treatment is insufficient. The aim of this study was to demonstrate the efficacy and safety of stent-assisted embolization of «acute» cerebral aneurysms. Material and methods. A retrospective analysis of the treatment of 234 patients with «acute» cerebral aneurysms was carried out. Results. Only coils were used in 40.6 % of cases (n = 95), balloon-assistance, in 40.2 % of cases (n = 94), and stent-assistance, in 19.2 % of cases (n = 45). There were 11.5 % (n = 27) clinically significant complications. Total aneurysm occlusion (Raymond-Roy I) was achieved in 187 cases (79.9 %); the radicality at the control examination was 67.1 % (157 patients). Discussion. The radicality of the treatment with stents was slightly higher then with balloons and coils at the end of operation (84.4 %, n = 38 and 78.8 %, n = 149, p > 0.05), but it was significantly higher at the control examination (80.0 %, n = 36 and 60.8 %, n = 115, respectively, p <0.05). Also, we had no statistically significant difference of the complication rate in the «stent» and «no stent» groups; therefore, the clinical outcomes of endovascular treatment of cerebral aneurysms did not depend on the choice of treatment method. Conclusions. Intracranial stents allow achieving good results of the embolization of complex aneurysms in the acute period of intracranial hemorrhage without increasing the risk of surgical treatment

Клинические особенности системной красной волчанки, протекающей с поражением органов дыхания

Summary. A retrospective cohort study of 105 patients with systemic lupus erythematosus (SLE) was held. Patients were divided in 2 groups: 1) those with pulmonary involvement (n = 63) and 2) those without pulmonary involvement (n = 42). Standard clinical and biochemical examination, immunological tests, hemostasis assessment, electrocardiography, echocardiography, chest X-ray examination were performed. We noted that SLE with pulmonary involvement was accompanied by significantly more frequent lesions of cardiovascular and digestive systems, IgA level abnormalities and radiological signs of deformed and increased pulmonary vascularity, blurred hilus and pleural thickening.Резюме. Было проведено ретроспективное когортное исследование с участием 105 пациентов, разделенных на 2 группы. В 1-ю группу вошли больные системной красной волчанкой (СКВ) с поражением органов дыхания (n = 63). Во 2-ю группу были включены пациенты с СКВ без поражения органов дыхания (n = 42). В обеих группах оценивались результаты проведенных стандартных исследований (общеклинического, биохимического и иммунологического), оценка системы гемостаза, электрокардиограмма, эхокардиограмма, стандартное рентгенологическое исследование органов грудной клетки. Установлено, что течение СКВ у пациентов с поражением органов дыхания статистически значимо чаще сопровождается поражением системы кровообращения и желудочно-кишечного тракта, колебаниями уровня JgА относительно нормы и рентгенологическими признаками усиления, деформации и сгущения легочного рисунка, неструктурности корней и наличия плевральных наложений

Being as intentional object of thinking and “Unity of being” in Parmenids

We propose the interpretation of Parmenides’ poem in which “indivisibility” of things is justified. It is shown that there are good reasons for the interpretation of what-is in Parmenides as an internal object of thinking, which is defined only all at once, completely, by all the characteristics that are attributed to that object in subject’s act of thinking. So, we develop J. Barrington’s treatment of what-is in Parmenides. We also show that Parmenides could mean in Doxa that any apprehended objects are different if and only if they can be apprehended separately. We propose a formalization of these Parmenides’ assumptions on objects of thinking. We construct this formalization by the instrumentality of B. Linsky & E. Zalta’s Theory of abstract objects . We demonstrate how this formalism imply Parmenides’ thesis on “indivisibility” of what-is, which we interpret as assertion of our inability to distinguish between propositions, which are defining an internal object of thought, or to distinguish between properties attributed to the internal object of thinking. We also point out the respects in which our interpretation is similar to “predicational monism”, attributed to Parmenides by P. Curd, and in which respects it is different from it

Development of methodical instruments of obtaining, research and control of electrophysical service properties of nanostructure composites

The article highlights the main problems of development of methodical instruments of obtaining, research and control of electrophysical service properties of nanostructure composites. Some of the results obtained at the research performed by scientists from National Research Nuclear University MEPhI (Moscow Engineering Physics Institute) and National Research University St. Petersburg State Polytechnical University are presented. The results are discussed in the focus of development of a new general method of control of electrophysical service properties of materials and products of nanostructured composites during the manufacturing process

Oscillations in Orthopositronium Annihilation in Magnetic Field in SiO2\text{}_{2} Powders

The observation method of γ-quantum angular distribution oscillations in positronium annihilation in magnetic field is essentially improved. Oscillation parameters in the experiment are in agreement with theoretical estimations