FINITE ELEMENT FOR STRESS-STRAIN STATE MODELING OF TWO-LAYERED AXIALLY SYMMETRIC SHELLS

Subject of Research. Computation of composite material designs requires application of numerical methods. The finiteelement method usage is connected with surface approximation problems. Application of volumetric and laminar elements leads to systems with large sizes and a great amount of computation. The objective of this paper is to present an equivalent two-layer mathematical model for evaluation of displacements and stresses of cross-ply laminated cone shells subjected to uniformly distributed load. An axially symmetric element for shell problems is described. Method. Axially symmetric finite element is proposed to be applied in calculations with use of correlation for the inner work of each layer separately. It gives the possibility to take into account geometric and physical nonlinearities and non-uniformity in the layers of the shell. Discrete mathematical model is created on the base of the finite-element method with the use of possible motions principle and Kirchhoff–Love assumptions. Hermite element is chosen as a finite one. Cone shell deflection is considered as the quantity sought for. Main Results. One-layered and two-layered cone shells have been considered for proposed mathematical model verification with known analytical and numerical analytical solutions, respectively. The axial displacements of the two-layered cone are measured with an error not exceeding 5.4 % for the number of finite elements equal to 30. The proposed mathematical model requires fewer nodes to define the finite element meshing of the system and much less computation time. Thereby time for finding solution decreases considerably. Practical Relevance. Proposed model is applicable for computation of multilayered designs under axially symmetric loads: composite high-pressure bottles, cylinder shaped fiberglass pipes, reservoirs for explosives and flammable materials, oil and gas storage tanks

Адаптированные алгоритмы Dual Contouring и Marching Cubes для 3D-реконструкции поясничного отдела позвоночника человека

The article deals with the problem of three-dimensional reconstruction of the human lumbar spine using the Marching Cubes and Dual Contouring surface triangulation algorithms for subsequent planning of a surgical intervention based on the analysis of digital computed tomography images. 3D reconstructions of the human lumbar spine are presented, as well as the results of a comparative analysis of the developed methods according to the following criteria: mesh generation speed; the number of generated cells; the absence of conflict situations (intersections of the surface). The optimal algorithm for solving the problem is determined on the basis of a comparative analysis.В статье рассматривается задача трехмерной реконструкции поясничного отдела позвоночника человека алгоритмами триангуляции поверхности Marching Cubes и Dual Contouring для последующего планирования хирургического вмешательства на основе анализа цифровых компьютерно-томографических изображений. Представлены 3D-реконструкции поясничного отдела позвоночника человека, а также результаты сравнительного анализа разработанных методов по следующим критериям: скорость генерации сетки, количество сгенерированных ячеек, отсутствие конфликтных ситуаций (пересечений поверхности). Оптимальный алгоритм для решения поставленной задачи определен на основании сравнительного анализа

ПРИМЕНЕНИЕ АВТОМАТИЗИРОВАННОГО КЛАССИФИКАТОРА РЕЗУЛЬТАТОВ КОМПЬЮТЕРНОЙ ТОМОГРАФИИ ДЛЯ ПОСТРОЕНИЯ ГЕОМЕТРИЧЕСКОЙ МОДЕЛИ ПОЗВОНКА ЧЕЛОВЕКА

The results of the study of a lumbar spine three-dimensional geometric model basic parameters were adduced. Modeling process was based on a spine computer tomography images received by the Gomel regional clinical hospital. The automated system was worked out. It allows to measure the geometric model basic parameters on a base of images of cross-sections of the vertebrae in the DICOM format.Приведены результаты исследования состава основных параметров трехмерной геометрической модели поясничного отдела позвоночника человека. Информационную базу моделирования составляют изображения в формате DICOM [1], полученные в результате компьютерной томографии позвоночника ряда пациентов Гомельской областной клинической больницы. Разработана автоматизированная система, выполняющая измерение изображений моделируемых органов и синтез геометрической модели

Colossal variations in the thermopower and n-p conductivity switching in topological tellurides under pressure

Under applied high pressure, the electronic, optical, structural, and other properties of narrow-bandgap telluride semiconductors are subjected to dramatic changes. They can include, for instance, structural and electronic topological transitions. In this work, we investigated the electronic properties of single crystals of three families of tellurides, namely, HgTe, PbTe, and Bi2Te3 by measurements of the thermoelectric power (the Seebeck coefficient) and electrical resistance under high pressure up to 10 GPa. The applied pressure led to spectacular variations in the electronic transport of all three tellurides. We addressed these effects to electronic topological transitions that could be driven by significant narrowing of the bandgaps in the normal-pressure phases of these compounds. In particular, at about 1 GPa, we observed an n-p switching in the conductivity of HgTe, which was well reproducible under multiple pressure cycling. In contrast, in PbTe, we found that an electronic topological transition irreversibly turns the conductivity from p- to n-type. An electronic topological Lifshitz transition in p-type Bi2Te3 crystals with a low carrier concentration enhanced the n-type conductivity in a narrow pressure region about 2-3 GPa and resulted in a double p-n-p conductivity inversion. An irreversible p-n conductivity switching in p-type Bi2Te3 happened already on decompression from a high-pressure phase from about 8 GPa. The stress-controlled p-n inversions of the electrical conductivity in these industrially important telluride materials can potentially find emergent applications in micro- and nanoelectronics. © 2020 Author(s).The research was supported by a grant of Ministry of Science and Higher Education of the Russian Federation No. 075-15-2020-797 (13.1902.21.0024)

Математическая модель принятия решений при лечении остеохондроза поясничного отдела позвоночника

The results of formalization of the decision-making logics in a field of osteochondrosis treatment are presented. The symptoms of the disease, determining the need for various methods of therapy, are selected. The mathematical model of lumbar spine state is developed. It allows to classify (recognize) spine states requiring principally different treatments. Key descriptors determining the choice of a conservative or operative intervention have been identified. Solutions that can be fully and partially automated are identified.Представлены результаты формализации логики принятия решений о выборе общего направления лечения остеохондроза позвоночника – консервативной или оперативной схемы лечения. Выделены симптомы заболевания, определяющие необходимость применения различных методов лечения. Построена математическая модель, описывающая состояние одного позвоночно-двигательного сегмента поясничного отдела позвоночника под воздействием дегенеративно-дистрофического процесса и позволяющая выполнить классификацию (распознавание) состояний позвоночника, которые требуют принципиально различных схем лечения. Выявлены ключевые дескрипторы, необходимые для описания логики принятия решений при диагностике и выборе направления лечения поясничного остеохондроза. Выделены решения, поддающиеся полной и частичной автоматизации

ИНТЕГРАЛЬНЫЙ МЕТОД ПОСТРОЕНИЯ МАТЕМАТИЧЕСКОЙ МОДЕЛИ И АЛГОРИТМА ИССЛЕДОВАНИЯ ВЯЗКОУПРУГИХ ДЕФОРМАЦИЙ ГРУНТОВЫХ ОСНОВАНИЙ

On the basis of the Boltzmann L. – Volterra V. hereditary creep theory a mathematical model, an algorithm and software for numerical investigation of viscous-elastic deformation of the non-uniform soil base have been developed. The algorithm for investigations of mathematical model is synthesized on the basis of a final element method that allows to take into account heterogeneity of a disperse body.На основе теории наследственной ползучести Больцмана – Вольтерра разработаны математическая модель, алгоритм и программное обеспечение для численного исследования вязкоупругого деформирования неоднородного грунтового основания. Алгоритм исследования математической модели разработан на основе метода конечных элементов, что позволяет учесть неоднородность дисперсного тела

Компьютерное моделирование перенапряжений в распределительных сетях 6–10 кВ при однофазных замыканиях на землю

Nowadays, when designing and operating electric power systems, special attention is paid to predicting emergency situations and minimizing losses in case they occur. The most common method of overvoltage investigations is the use of simulation models in specialized application packages, which imposes additional qualification requirements on the electrical engineer.The authors propose modeling technologies and a software tool for modeling and research of overvoltages that occur in 6–10 kV distribution networks at single-phase ground faults, including the method of visual design of the distribution network through the use of information technology and automated generation of mathematical model for its further study to analyze overvoltages.В настоящее время при проектировании и эксплуатации электроэнергетических систем особое внимание уделяется прогнозирования возникновения аварийных ситуаций и минимизации потерь в случае их появления. Наиболее распространёнными методом исследования перенапряжений являются применение имитационных моделей в специализированных прикладных пакетах, что накладывает дополнительные квалификационные требования на энергетика-проектировщика.Авторами предлагается технологии моделирования и программное средство для моделирования и исследования перенпряжений, возникающих в распределительных сетях 6–10 кВ при однофазных замыканиях на землю, включающее методику визуального проектирования распределительной сети посредством применения информационных технологий и автоматизированную генерацию математической модели для её дальнейшее исследование с целью анализа перенапряжений

KLEVER: An experiment to measure BR(KL→π0ννˉK_L\to\pi^0\nu\bar{\nu}) at the CERN SPS

Precise measurements of the branching ratios for the flavor-changing neutral current decays $K\to\pi\nu\bar{\nu}$ can provide unique constraints on CKM unitarity and, potentially, evidence for new physics. It is important to measure both decay modes, $K^+\to\pi^+\nu\bar{\nu}$ and $K_L\to\pi^0\nu\bar{\nu}$, since different new physics models affect the rates for each channel differently. The goal of the NA62 experiment at the CERN SPS is to measure the BR for the charged channel to within 10%. For the neutral channel, the BR has never been measured. We are designing the KLEVER experiment to measure BR($K_L\to\pi^0\nu\bar{\nu}$) to $\sim$20% using a high-energy neutral beam at the CERN SPS starting in LHC Run 4. The boost from the high-energy beam facilitates the rejection of background channels such as $K_L\to\pi^0\pi^0$ by detection of the additional photons in the final state. On the other hand, the layout poses particular challenges for the design of the small-angle vetoes, which must reject photons from $K_L$ decays escaping through the beam exit amidst an intense background from soft photons and neutrons in the beam. Background from $\Lambda \to n\pi^0$ decays in the beam must also be kept under control. We present findings from our design studies for the beamline and experiment, with an emphasis on the challenges faced and the potential sensitivity for the measurement of BR($K_L\to\pi^0\nu\bar{\nu}$).Comment: 13 pages, 4 figures. Submitted as input to the 2020 update of the European Strategy for Particle Physics. v2: Included authors unintentionally omitted in v

Measurement of associated charm production induced by 400 GeV/c protons

An important input for the interpretation of the measurements of the SHiP ex- periment is a good knowledge of the differential charm production cross section, including cascade production. This is a proposal to measure the associated charm production cross section, employing the SPS 400 GeV/c proton beam and a replica of the first two interaction lengths of the SHiP target. The detection of the produc- tion and decay of charmed hadron in the target will be performed through nuclear emulsion films, employed in an Emulsion Cloud Chamber target structure. In order to measure charge and momentum of decay daughters, we intend to build a mag- netic spectrometer using silicon pixel, scintillating fibre and drift tube detectors. A muon tagger will be built using RPCs. An optimization run is scheduled in 2018, while the full measurement will be performed after the second LHC Long Shutdown