Control of the magnitude and spatial distribution of interference energy flows in near fields of systems of identical radiators

The problem of active control for both the magnitude and spatial distribution of individual components of the interference component of the Poynting vector within the near zone of a system of radiators is studied. The characteristic size of this zone is on the order of the wavelength and is characterized by the presence of evanescent (nonpropagating) fields, which are formed due to the interference interaction of radiators. Using multipole expansions for fields and special summation formulas for such expansions allows one to obtain concise expressions convenient in carrying out numerical calculations. The results of calculations confirm the feasibility of the above-mentioned control in principle in solving problems of medium and object sensing

The role played by evanescent fields in the process of formation of radiation of combined radiating systems

The problem of active controlling of the structure of fields of combined radiating systems within their near zone is studied. The characteristic size of this zone is on the order of the wavelength and is characterized by the presence of evanescent (nonpropagating) fields, which are formed, among other things, due to the interference interaction of radiators of the system. Using multipole expansions for fields and special summation formulas for such expansions allows one to obtain concise expressions convenient in carrying out numerical calculations. The results of calculations confirm that the evanescent fields’ structure plays a significant part in the process of the formation of the radiation field

Фракционная анизотропия белого и серого вещества головного мозга в остром периоде ишемического инсульта как маркер неврологического, когнитивного и функционального статуса

Aim. To study the fractional anisotropy of white and gray brain matter and its associations with clinical and instrumental data in acute ischemic stroke. Materials and methods. The parameters of fractional anisotropy of 10 areas of white and gray brain matter were analyzed in 30 acute ischemic stroke patients by diffusion-tensor imaging. The neurological (NIHSS), cognitive (MMSE), functional (Rivermead Mobility Index and Modified Rankin Scale) and some laboratory and instrumental data were assessed. Results. The fraction anisotropy was analyzed on the side of lesion and symmetrically. The decline of anisotropy was revealed in posterior limb of internal capsule on the side of stroke independently of the lesion location. Also the interactions between fraction anisotropy and stroke severity, global cognitive status and duration of hospital treatment were found. Conclusion. The obtained data may suggest that in acute period of stroke the neurodegeneration and neuroreparational ready start. It appears the changes of white and gray matter integrity. According to the concept “heart-vessels-brain” we received the data indicating the significance of vascular risk factors which lead to hypoperfusion and hypoxia in the development of microstructural changes. Some parameters of fractional anisotropy may predict clinical and functional outcome on discharge.Цель исследования: оценить фракционную анизотропию белого и серого вещества головного мозга и ее связь с клинико-инструментальными характеристиками в остром периоде ишемического инсульта. Материал и методы. Измерены показатели фракционной анизотропии 10 зон белого и серого вещества головного мозга у 30 пациентов в остром периоде ишемического инсульта методом диффузионно-тензорного изображения. Оценены показатели неврологического (NIHSS), когнитивного (MMSE), функционального статусов (индекс мобильности Ривермид и модифицированная шкала Ренкина), а также лабораторно-инструментальные данные. Результаты. Проанализированы различия фракционной анизотропии на стороне очага поражения и симметричных участках головного мозга. Выявлено снижение показателя в зоне задней ножки внутренней капсулы на стороне очага по сравнению с симметричными зонами интактного полушария вне зависимости от расположения зоны инфаркта. Продемонстрирована взаимосвязь между значениями фракционной анизотропии в исследованных зонах со степенью неврологического дефицита и когнитивным статусом при выписке, а также длительностью лечения. Заключение. Проведенное исследование может свидетельствовать о том, что уже в остром периоде ишемического инсульта параллельно инициируются процессы нейродегенерации и нейрорепарации, проявляющиеся изменением интегральности белого и серого вещества головного мозга. В подтверждение концепции “сердце-сосуды-мозг” получены данные о значимости сосудистых факторов риска, обусловливающих гипоперфузию и гипоксию, в развитии микроструктурных изменений изученных зон мозга. Ряд показателей фракционной анизотропии, рассмотренных в работе, могут служить предикторами неврологического и функционального исхода при выписке пациентов из стационара

Амилоид-бета 40 как биомаркер когнитивных нарушений в остром периоде ишемического инсульта

Aim: to study the role of amyloid-beta 40 (Aβ 40) in the development of cognitive impairment in acute ischemic stroke.Materials and methods. The study included 70 patients aged 33–86 years, 46 men and 24 women. In patients with acute ischemic stroke cognitive status was assessed with Mini-Mental State Examination (MMSE), Montreal Cognitive Assessment Test (MoCA), Frontal Assessment Battery (FAB), Schulte tables, Clock Drawing Test, Test for Semantic Verbal Fluency and Five Words Test. The concentration of Aβ 40 in the cerebrospinal fluid was determined. Morphometric (size of the infarct and leukoaraiosis area, volume of the brain ventricles and hippocampus) and diffusion-tensor parameters of MRI (fractional anisotropy of putamen, thalamus, hippocampus, corpus callosum, limbs of the internal capsule, the cingulate, the superior longitudinal and inferior fronto-occipital tracts) were studied.Results. The concentration of Aβ 40 in the cerebrospinal fluid was 436,4 (226,0–514,0) pg/ml. The protein level was associated with the result of subtests «Orientation» (MMSE) and «Attention» (MoCA), as well as indirect recall with cues in MoCA. Patients with MMSE score of 24–27 points were characterized by a lower concentration of Aβ 40 as compared to patients with a score less than 24 points. Aβ 40 concentration more than 436,4 pg/mL was associated with a more severe somatic co-morbidity of stroke (hypertension, lower hemoglobin and albumin level, higher erythrocyte sedimentation rate), a smaller volume of the brain ventricles, lower fractional anisotropy of the thalamus, cingulate tracts and contralateral hippocampus. Aβ 40 concentration more than 436,4 pg/mL was also associated with a lower global cognitive status (according to the MMSE and MoCA), as well as the reduction in certain cognitive functions, namely, attention, visual-spatial functions and memory.Conclusions. The concentration of Aβ 40 in the cerebrospinal fluid is a biological marker of severity type of post-stroke cognitive impairment. This interaction is probably due to the damage to the hippocampus, thalamus and cingulate tracts. In our opinion, the biomarker reflects both ischemic and neurodegenerative components of the pathogenesis of cognitive impairment in acute ischemic stroke.Цель исследования. Изучение роли амилоида-бета 40 (Aβ 40) в развитии когнитивных нарушений в остром периоде ишемического инсульта.Материал и методы. Обследованы 70 пациентов в возрасте 33–86 лет, из которых 46 мужчин и 24 женщины.У пациентов в остром периоде ишемического инсульта проводилась оценка когнитивного статуса (краткая шкала оценки психического статуса (MMSE), Монреальская шкала оценки когнитивных функций (MoCA), батарея лобных тестов (FAB), таблицы Шульте, тест рисования часов, тест на семантическую вербальную беглость и тест пяти слов). Также исследовалась концентрации Аβ 40 в ликворе, изучались морфометрические (размер очага инфаркта и площадь лейкоареоза, объем желудочков мозга и гиппокампов) и диффузионно-тензорные показатели (фракционная анизотропия скорлупы, таламуса, гиппокампа, мозолистого тела, ножек внутренней капсулы, цингулярного, верхнего продольного и нижнего фронто-окципитального пучков) магнитно-резонансной томографии.Результаты. Концентрация Аβ 40 в ликворе составила 436,4 (226,0–514,0) пг/мл и была ассоциирована с результатом субтестов «ориентация» (MMSE) и «внимание» (MoCA), а также опосредованным воспроизведением в MoCA. Пациенты с результатом MMSE 24–27 баллов характеризовались более низкой концентрацией Аβ 40 по сравнению с пациентами с результатом шкалы менее 24 баллов. Концентрация Аβ 40 более 436,4 пг/мл была связана с более выраженной соматической коморбидностью инсульта (артериальная гипертензия, более низкое содержание гемоглобина и альбумина крови, более высокая скорость оседания эритороцитов), меньшим объемом желудочков мозга, более низкой фракционной анизотропией таламусов, цингулярных пучков и контралатерального гиппокапма и ассоциирована с более низким глобальным когнитивным статусом (по результатам MMSE и MoCA), а также снижением отдельных когнитивных функций, а именно внимания, зрительно-пространственного гнозиса и памяти.Выводы. Концентрация Аβ 40 в спинномозговой жидкости является биологическим маркером как выраженности, так и характера постинсультных когнитивных нарушений, что, вероятно, опосредовано повреждением гиппокампов, таламуса и цингулярных трактов. При этом, на наш взгляд, биомаркер отражает как сосудистый, или ишемический, компонент патогенеза когнитивных нарушений в остром периоде ишемического инсульта, так и влияние амилоид-опосредованной нейродегенерации

Development of a digital model of the working process of a hydraulic excavator

In this work, we consider a method for determining the rational values of the structural and operational parameters of the lever - hydraulic mechanisms of hydraulic excavators based on an analysis of the results of a computational experiment obtained at the output of a mathematical model of a workflow. It is shown that the presence of kinematic connections between the engine (hydraulic cylinder) and the links of the lever-hydraulic mechanism causes a change in the relationship between the operating parameters of the engine and the power parameters implemented on the driven members (bucket, handle and arrow), depending on the geometric parameters (lengths) of links and coordinates of points (axes) connections links. A simulation model of the working process is developed, which allows to determine the operational parameters of the lever - hydraulic mechanisms

Features of designing hydraulic excavator in APM WinMachine

The urgency of the work is due to the need for design departments involved in the design of hydraulic excavators in techniques. Allowing to reduce the weight of excavators while providing at the same time sufficient reliability. The purpose of the work: development of a technique for application in the design of excavators of calculation modules based on the use of finite elements. Research methodology: modeling of working equipment. For a hydraulic excavator with a “direct” shovel working equipment, a mathematical model for calculating effort, an algorithm and a program in an algorithmic language have been developed, which allow to determine the working area of the excavator, possible digging forces, and efforts in the elements of the working equipment. To calculate stresses in the design of the working equipment, two modeling options are proposed: the models for the Strucrure 3D computational module are compiled separately for the bucket of the handle and the boom, the interaction of the models is carried out by efforts that are determined by the specified digging forces; a complete model of all the working equipment for the calculation module is compiled, without the need to calculate the loads between the elements, the calculation is carried out directly by the digging force. For the first variant formulas of calculation of efforts in elements of the working equipment are resulted. For the second variant, it is suggested to use a plate-rod model, and recommendations are given for the implementation of the relationships between the boom, the handle and the bucket. The results of stress calculations for the working equipment are presented

Control of the magnitude and spatial distribution of interference energy flows in near fields of systems of identical radiators

The problem of active control for both the magnitude and spatial distribution of individual components of the interference component of the Poynting vector within the near zone of a system of radiators is studied. The characteristic size of this zone is on the order of the wavelength and is characterized by the presence of evanescent (nonpropagating) fields, which are formed due to the interference interaction of radiators. Using multipole expansions for fields and special summation formulas for such expansions allows one to obtain concise expressions convenient in carrying out numerical calculations. The results of calculations confirm the feasibility of the above-mentioned control in principle in solving problems of medium and object sensing

The role played by evanescent fields in the process of formation of radiation of combined radiating systems

The problem of active controlling of the structure of fields of combined radiating systems within their near zone is studied. The characteristic size of this zone is on the order of the wavelength and is characterized by the presence of evanescent (nonpropagating) fields, which are formed, among other things, due to the interference interaction of radiators of the system. Using multipole expansions for fields and special summation formulas for such expansions allows one to obtain concise expressions convenient in carrying out numerical calculations. The results of calculations confirm that the evanescent fields’ structure plays a significant part in the process of the formation of the radiation field

Analysis of Influence of Heat Insulation on the Thermal Regime of Storage Tanks with Liquefied Natural Gas

Is numerically investigated the process of convective heat transfer in the reservoirs of liquefied natural gas (LNG). The regimes of natural convection in a closed rectangular region with different intensity of heat exchange at the external borders are investigated. Is solved the time-dependent system of energy and Navier-Stokes equations in the dimensionless variables “vorticity – the stream function”. Are obtained distributions of the hydrodynamic parameters and temperatures, that characterize basic regularities of the processes. The special features of the formation of circulation flows are isolated and the analysis of the temperature distribution in the solution region is carried out. Is shown the influence of geometric characteristics and intensity of heat exchange on the outer boundaries of reservoir on the temperature field in the LNG storage