Computational analysis of high frequency fluid–structure interactions in constricted flow

Constricted flow in a thin cylindrical shell with an idealized blunt constriction is modeled using ADINA. Highly disturbed recirculation region is observed at the constriction exit where pressure fluctuations and consequential vessel wall vibrations display broadband spectral content over a range of several hundred Hz. Maximum dynamic pressure and vibration amplitudes are observed around the reattachment point and they gradually decrease along downstream of flow. Results obtained by numerical simulations are compared with relevant studies in the literature and are in good agreement in terms of general spectral behavior. However, the amplitudes were significantly lower as compared to experimental results

Computational analysis of high frequency fluid-structure interactions in constricted flow

Constricted flow in a thin cylindrical shell with an idealized blunt constriction is modeled using ADINA. Highly disturbed recirculation region is observed at the constriction exit where pressure fluctuations and consequential vessel wall vibrations display broadband spectral content over a range of several hundred Hz. Maximum dynamic pressure and vibration amplitudes are observed around the reattachment point and they gradually decrease along downstream of flow. Results obtained by numerical simulations are compared with relevant studies in the literature and are in good agreement in terms of general spectral behavior. However, the amplitudes were significantly lower as compared to experimental results

Kan Damarlarındaki Daralma Seviyesi ve Şekillerinin Tanısal Amaçlı Olarak Kullanımının Sayısal Benzetimlerle İncelenmesi

Stenoz probleminin akışkanlar mekaniği kısmına odaklanılacak ve problem sayısal tekniklerle çözülecektir. Özellikle damardaki daralma sonrasında oluşan yüksek frekanslı basınç dalgalanmaları incelenecek ve daralma mertebesi ve şeklinin bu dalgalanmalara olan etkisi araştırılacaktır

Исследование возможностей современных компьютерных программ для расчета оболочек сложной геометрии

Relevance. In design and calculation of civil engineering structures, several standard commercial software packages, which are successfully applied to solve everyday engineering problems, are traditionally used. However, when it is necessary to design the models of complex shape shell structures with defining surfaces based on parametric equations, such programs often have certain drawbacks. The aim of the work - analysis of existing types of commercial computational software packages in order to check which allow to design finite element models for shell structures with median surfaces of complex geometry given by parametric equations. Methods. The analysis of commercial computational software packages is carried out by studying the software manuals, and by building and calculating a model in the shape of a right helicoid as a test example. To evaluate the results of the stress-strain state of a shell with a middle surface in the form of a right helicoid, an analytical calculation method based on the Reissner’s equations and Fourier series expansion is used. Results. A review of modern commercial computational software packages as applied to models defined by parametric equations is carried out. A model for a shell structure with a median surface in the form of right helicoid is built. The numerical results of stress-strain behavior of the right helicoid are obtained and analyzed in comparison with the analytical solutions obtained using the Reissner’s equations with Fourier series expansion. The pros and cons of several popular means of software are presented.Актуальность. При проектировании и расчете строительных конструкций традиционно используются несколько стандартных коммерческих пакетов программного обеспечения, которые успешно применяются для решения повседневных инженерных задач. Однако, когда необходимо разработать модели структур оболочек сложной формы с заданием поверхностей с помощью параметрических уравнений, такие программы зачастую имеют определенные недостатки. Цель исследования - проанализировать существующие типы коммерческих вычислительных программных пакетов с целью определения позволяющих проектировать конечно-элементные модели для конструкций оболочек со срединными поверхностями сложной геометрии, заданными параметрическими уравнениями. Методы. Анализ коммерческих вычислительных программных пакетов выполнялся путем изучения руководств по программному обеспечению, а также построения и расчета модели в форме прямого геликоида в качестве тестового примера. Для оценки результатов напряженно-деформированного состояния оболочки со срединной поверхностью в форме прямого геликоида использовался аналитический метод расчета, основанный на уравнениях Рейсснера и разложении решения в ряды Фурье. Результаты. Проведен обзор современных коммерческих вычислительных программных пакетов применительно к моделям, задаваемым параметрическими уравнениями. Построена модель оболочки со срединной поверхностью в форме прямого геликоида. Численные результаты напряженно-деформированного состояния этой оболочки получены и проанализированы в сравнении с аналитическими решениями, вычисленными с использованием уравнений Рейсснера с разложением решения в ряды Фурье. Представлены плюсы и минусы нескольких популярных программных комплексов

Solar Power Generation Analysis and Forecasting Real-World Data Using LSTM and Autoregressive CNN

Generated power of a solar panel is volatile and susceptible to environmental conditions. In this study, we have analyzed variables affecting the generated power of a 17.5 kW real-world solar power plant with respect to five independent variables over the generated power: irradiance, time of measurement, panel's temperature, ambient temperature and cloudiness of the weather at the time of measurement. After our analysis, we have trained three different models to predict intra-day solar power forecasts of the plant. Our models are able to predict future power output of the solar power plant with less than 10% RMSE without requiring additional sensor data, e.g. a camera to observe clouds. Based on our forecasting accuracy, our study promises: fast, scaleable and effective solutions to solar power plant maintainers and may facilitate grid safety on a large scale

Hot Isostatic Pressing of Aluminum–Silicon Alloys Fabricated by Laser Powder-Bed Fusion

Hot isostatic pressing can be utilized to reduce the anisotropic mechanical properties of Al–Si–Mg alloys fabricated by laser powder-bed fusion (L-PBF). The implementation of post processing densification processes can open up new fields of application by meeting high quality requirements defined by aircraft and automotive industries. A gas pressure of 75 MPa during hot isostatic pressing lowers the critical cooling rate required to achieve a supersaturated solid solution. Direct aging uses this pressure related effect during heat treatment in modern hot isostatic presses, which offer advanced cooling capabilities, thereby avoiding the necessity of a separate solution annealing step for Al–Si–Mg cast alloys. Hot isostatic pressing, followed by rapid quenching, was applied to both sand cast as well as laser powder-bed fused Al–Si–Mg aluminum alloys. It was shown that the critical cooling rate required to achieve a supersaturated solid solution is significantly higher for additively manufactured, age-hardenable aluminum alloys than it is for comparable sand cast material. The application of hot isostatic pressing can be combined with heat treatment, consisting of solution annealing, quenching and direct aging, in order to achieve both a dense material with a small number of preferred locations for the initiation of fatigue cracks and a high material strength