scholarly journals Structural health monitoring and structural modifications of industrial building subjected to dynamic loading

2020 ◽  
Vol 313 ◽  
pp. 00021
Author(s):  
Robert Soltys ◽  
Michal Tomko ◽  
Ivo Demjan
Keyword(s):  
Load Transfer ◽  
Steel Structure ◽  
Industrial Building ◽  
Construction Work ◽  
Structural Behaviour ◽  
Structural Modifications ◽  
Power Spectral ◽  
Power Spectral Densities ◽  
Before And After ◽  
Complex Structural

A complex structural, static and dynamic review of an existing steel ceiling has been realised after two years of service and the completion of subsequent construction work. The construction work involved the reconstruction of a steel structure and structural modifications to the ceiling, which is part of the production hall. The construction work was realised in order to reduce the vibration response of the ceiling. The interior of the steel structure was supplemented by steel structural elements to share the load transfer of automatic washing machines. The structural behaviour of the ceiling was monitored before and after the modification. Accelerations of the ceiling were time-domain-monitored at specific locations. Measured data was transformed to the spectral-domain which is represented by power spectral densities.

Detection of Vehicle Tripped and Untripped Rollovers by a Novel Index With Mass-Center-Position Estimations

2017 ◽  
Author(s):  
Fengchen Wang ◽  
Yan Chen
Keyword(s):  
Load Transfer ◽  
Center Of Mass ◽  
Roll Motion ◽  
Mass Center ◽  
Motion Models ◽  
Center Position ◽  
Before And After ◽  
Vehicle Rollover ◽  
Lift Off ◽  
Rollover Index

This paper presents a novel mass-center-position (MCP) metric for vehicle rollover propensity detection. MCP is first determined by estimating the positions of the center of mass of one sprung mass and two unsprung masses with two switchable roll motion models, before and after tire lift-off. The roll motion information without saturation can then be provided through MCP continuously. Moreover, to detect completed rollover statues for both tripped and untripped rollovers, the criteria are derived from d’Alembert principle and moment balance conditions based on MCP. In addition to tire lift-off, three new rollover statues, rollover threshold, rollover occurrence, and vehicle jumping into air can be all identified by the proposed criteria. Compared with an existing rollover index, lateral load transfer ratio, the fishhook maneuver simulation results in CarSim® for an E-class SUV show that MCP metric can successfully predict the vehicle impending rollover without saturation for untripped rollovers. Tripped rollovers caused by a triangle road bump are also successfully detected in the simulation. Thus, MCP metric can be successfully applied for rollover propensity prediction.

Combined Reinforced Concrete Columns Strengthening with Steel Clipping and Concrete Surfacing

2021 ◽  
pp. 11-22
Author(s):  
Ю. Г. Москалькова ◽  
С. В. Данилов ◽  
В. А. Ржевуцкая
Keyword(s):  
Reinforced Concrete ◽  
Load Transfer ◽  
Limit State ◽  
Concrete Columns ◽  
Ultimate Limit State ◽  
Concrete Core ◽  
Reinforced Concrete Columns ◽  
Entire Height ◽  
Complex Structural ◽  
Ultimate Limit

Постановка задачи. Исследуется метод усиления железобетонных колонн устройством стальной обоймы с обетонированием, который позволяет восстанавливать эксплуатационные показатели колонн, имеющих значительные дефекты и повреждения. Предпосылкой настоящих исследований явилось предположение о том, что усиление стальной обоймой с обетонированием является эффективным способом повышения несущей способности железобетонных колонн, причем вариант приложения нагрузки - только на бетонное ядро или ко всему сечению - существенно на эффективность усиления не влияет. В связи с этим целью исследования является определение необходимости устройства стального оголовка и включения в работу ветвей стальной обоймы при условии обетонирования стержня колонны по всей высоте. Результаты и выводы. Рациональным признан способ передачи нагрузки только на бетонное ядро усиленных колонн, поскольку устройство оголовка стальной обоймы требует применения сложных конструктивно-технологических решений, но при этом дополнительно увеличивает несущую способность незначительно (согласно проведенным исследованиям менее чем на 10 %). Ввиду отсутствия необходимости устройства конструкций стального оголовка снижаются трудоемкость и сроки производства работ по усилению колонн. Statement of the problem. The method of strengthening reinforced concrete columns with a steel clipping and the concrete surfacing is investigated. This method allows one to repair the columns with significant defects and damage. The prerequisite for this study was the assumption of strengthening with a steel clipping and the concrete surfacing is an effective way to increase the ultimate limit state of reinforced concrete columns, furthermore, the option of applying the load (only to the concrete core or to the entire section) does not significantly affect the strengthening effectiveness. In this regard, the purpose of the investigation was to identify the need to include the steel jacketing in the work, on the condition the column is coated with concrete along with the entire height. Results and conclusions. The load transfer method only to the concrete core of the strengthened columns is recognized as rational since the device of the steel clipping head requires the use of complex structural and technological solutions, but at the same time additionally increases the ultimate limit state insignificantly (according to the studies by less than 10 %). Due to the absence of the need to establish structures of the steel jacketing head, the labor intensiveness and terms of work production on strengthening the columns are reduced.

Analysis of power spectral densities of electrocardiograms

1971 ◽  
Vol 12 (1-2) ◽  
pp. 41-51 ◽  
Author(s):  
Vrudhula K. Murthy ◽  
L. Julian Haywood ◽  
John Richardson ◽  
Robert Kalaba ◽  
Steven Salzberg ◽  
...  
Keyword(s):  
Spectral Densities ◽  
Power Spectral ◽  
Power Spectral Densities

scholarly journals History, observation and mathematical models in the seismic analysis of the Valadier abutment area in the Colosseum

1995 ◽  
Vol 38 (5-6) ◽  
Author(s):  
G. Croci ◽  
D. D'Ayala ◽  
R. Liburdi
Keyword(s):  
Mathematical Models ◽  
Seismic Analysis ◽  
Numerical Models ◽  
Time History ◽  
Historical Records ◽  
Direct Integration ◽  
Structural Behaviour ◽  
Seismic Behaviour ◽  
Before And After ◽  
Xix Century

The present work aimed to outline the need to investigate different fields of research to interpret the structural behaviour of a monument as complex as the Colosseum. It is shown how defining the numerical models first. then refining them, followed by interpretation of results. is strictly linked with the inforination gathered from historical records and observation of the ~nonumenta s it is today. The study is confined to the area of the Valadier abutment. analysing its state and its seismic behaviour before and after the XIX century restoration using different ilumerical tools, from the elastic modal analysis to the non linear step by step time history direct integration. The procedure comparati\ely evaluates the reliability in the interpretation of the results and identifies future lines or research.

scholarly journals Delta and Theta waves in Super Consciousness Meditation.

2020 ◽  
Author(s):  
Anil Kumar Bheemaiah
Keyword(s):  
Average Power ◽  
Spectral Densities ◽  
Theta Wave ◽  
Convolutional Networks ◽  
Theta Waves ◽  
Power Spectral ◽  
Power Spectral Densities ◽  
Lyapunov Coefficient ◽  
Fmri Time Series ◽  
Power Densities

Study on Kundalini Meditation of Super-conscious Meditation of the Himalayan Tradition and Sahaja Meditation, to determine the average power spectral densities and power ratios of TP9, AF7, AF8, and TP10, electrodes and two ear electrodes on a Muse Headset.These parameters are used to create quantitative criteria to indicate degree of meditation and to create a trigger for bird chirp events.We find an increase in Delta and Theta wave power densities, in the deep meditation state as compared to the initiation and restful states. keywords: Kundalini, super consciousness, neurosky, muse, chakra based meditation, alpha to beta ratio, delta to beta ratio, power spectral densities, differential power spectral densities, fMRi, time series, iD convolutional networks. Lyapunov coefficient

scholarly journals Differences Amplitude Based Improvement of Minimum Variance Distortionless Response Filter

2020 ◽  
Vol 8 (5) ◽  
pp. 1635-1637
Keyword(s):  
A Priori ◽  
Minimum Variance ◽  
Coherent Noise ◽  
Noise Interference ◽  
Power Spectral ◽  
Minimum Variance Distortionless Response ◽  
Power Spectral Densities ◽  
Noisy Signals ◽  
A New Technique ◽  
Priori Information

In this work, the author introduces a new technique for improving the performance of minimum variance distortionless response filter in condition of coherent noise. The proposal algorithm exploits a priori information of differences amplitude to balance power spectral densities of observed noisy signals. The output signal of MVDR filter is then processed by an additional post-filtering, which based speech presence probability to suppress more noise interference and increase quality speech. In experiments using two noisy signal recordings in anechoeic room, the modified MVDR-filter results provides that the suggested algorithm increases speech quality compared to the conventional MVDR filter.

Analysis of earth motions and seismic sources by power spectral density

1969 ◽  
Vol 59 (3) ◽  
pp. 1071-1091
Author(s):  
Dean V. Power
Keyword(s):  
Spectral Density ◽  
Power Spectral Density ◽  
High Explosive ◽  
Peak Velocity ◽  
Test Site ◽  
Nevada Test Site ◽  
Spectral Densities ◽  
Power Spectral ◽  
Power Spectral Densities ◽  
Velocity Spectra

abstract Ground motion records from six high-explosive cratering events in northeastern Montana, ten contained nuclear explosive events at the Nevada Test Site, and motions of an earth-fill dam during the Gasbuggy underground nuclear explosion in New Mexico were analyzed for power spectral density, peak velocity and velocity spectra. The high-explosive events included four 20-ton single charges at depths of burst which varied between 42 to 57 feet, a 140-ton row charge consisting of three 20-ton and two 40-ton charges at optimum cratering depths of burst, and a 0.5-ton charge at the optimum depth of burst. It was found that at these depths and charge weights an increase in depth of burst resulted in an increase in peak velocities and power-spectral densities as measured at distant points (> 5 km). Power spectral density was found to be approximately proportional to the first power of yield. For this region it was determined that power spectral density varied inversely as radial distance to the 3.55 power. Three analysis techniques—peak velocity, velocity spectra and power spectral density—are compared, and it is shown that power spectral density is the most consistent method when comparing records from different measuring stations. An analysis of power-spectral density measured at one station for the ten events at the Nevada Test Site shows that a significant shift in the frequency of the energy in the seismogram occurs when the source location changes. For events in the Yucca Flat area the peak energy at Mercury was consistently at 1.0 Hz, while for events in the Pahute Mesa area this peak occurs at 2.5 Hz. A comparison of the power spectral densities on and near the Navajo Dam revealed that the natural frequencies and first harmonics of the dam are 1.4, 2.0 and 2.5 Hz in the mode where motion is parallel to the canyon axis. A simple model makes use of these frequencies to calculate a shear-wave velocity of 1130 ft/sec. A method of using power spectral density to measure earthquake magnitudes and measure the yield of underground explosions is proposed.

Using COVID19 as an Opportunity to Measure Seismic Silences and Bring Geoscience Projects to Students

2021 ◽  
Author(s):  
Artash Nath
Keyword(s):  
Northwest Territories ◽  
World Health ◽  
Virtual Classrooms ◽  
Power Spectral ◽  
Essential Services ◽  
Power Spectral Densities ◽  
The World ◽  
Seismic Vibrations ◽  
Health Organization ◽  
Almost All

<p>On 11 March 2020, the World Health Organization declared Covid19 a pandemic. Countries around the world rushed to declare various states of emergencies. Canada also implemented emergency measures to restrict the movements of people including the closure of borders, non-essential services, and schools and offices to slow the spread of Covid19. I used this opportunity to measure changes in seismic vibrations registered in Canada before, during, and after the lockdown due to the slowdown in transportation, economic, and construction activities. I analyzed continuous seismic data for 6 Canadian cities: Calgary and Edmonton (Alberta), Montreal (Quebec), Ottawa, and Toronto (Ontario), and Yellowknife (Northwest Territories). These cities represented the wide geographical spread of Canada. The source of data was seismic stations run by the Canadian National Seismograph Network (CNSN). Python and ObSpy libraries were used to convert raw data into probabilistic power spectral densities. The seismic vibrations in the PPSDs that fell between 4 Hz and 20 Hz were extracted and averaged for every two weeks period to determine the trend of seismic vibrations. The lockdown had an impact on seismic vibrations in almost all the cities I analyzed. The seismic vibrations decreased between 14% - 44% with the biggest decrease in Yellowknife in the Northwest Territories. In the 3 densely populated cities with a population of over 1 million - Toronto, Montreal, and Calgary, the vibrations dropped by over 30%.</p><p>To enable other students to undertake similar projects for their cities, I created a comprehensive online training module using Jupyter notebooks available on Github. Students can learn about seismic vibrations, how to obtain datasets, and analyze and interpret them using Python. They can share their findings with local policymakers so that they become aware of the effectiveness of the lockdown imposed and are better prepared for lockdowns in the future. When we make data and technology accessible, then lockdowns because of pandemics can be an opportunity for students to take up practical geoscience projects from home or virtual classrooms.</p>

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