85 research outputs found
A Software Architecture for Cognitive Technical Systems Suitable for an Assembly Task in a Production Environment
Non
Geometrical Nonlinearity on Collapse of Reinforced Concrete Piers
The objective of this study is to investigate the possible collapse mechanisms of reinforced concrete
columns. Analyses are performed to study the effect of both material and geometrical nonlinearities in the
post peak response of flexural columns. Discussion is mainly focussed on the restoring force
characteristics, especially in large deformation range, of RC columns having high shear capacity so that
the ultimate failure is governed by bending
Установка для измерения относительной напряженности электрического поля в объемных резонаторах
Probabilistic Quantification of the Effects of Soil-Shallow Foundation-Structure Interaction on Seismic Structural Response
Previous earthquakes demonstrated destructive effects of soil-structure interaction on structural response. For example, in the 1970 Gediz earthquake in Turkey, part of a factory was demolished in a town 135 km from the epicentre, while no other buildings in the town were damaged. Subsequent investigations revealed that the fundamental period of vibration of the factory was approximately equal to that of the underlying soil. This alignment provided a resonance effect and led to collapse of the structure. Another dramatic example took place in Adapazari, during the 1999 Kocaeli earthquake where several foundations failed due to either bearing capacity exceedance or foundation uplifting, consequently, damaging the structure. Finally, the Christchurch 2012 earthquakes have shown that significant nonlinear action in the soil and soil-foundation interface can be expected due to high levels of seismic excitation and spectral acceleration. This nonlinearity, in turn, significantly influenced the response of the structure interacting with the soil-foundation underneath.
Extensive research over more than 35 years has focused on the subject of seismic soil-structure interaction. However, since the response of soil-structure systems to seismic forces is extremely complex, burdened by uncertainties in system parameters and variability in ground motions, the role of soil-structure interaction on the structural response is still controversial. Conventional design procedures suggest that soil-structure interaction effects on the structural response can be conservatively ignored. However, more recent studies show that soil-structure interaction can be either beneficial or detrimental, depending on the soil-structure-earthquake scenarios considered.
In view of the above mentioned issues, this research aims to utilise a comprehensive and systematic probabilistic methodology, as the most rational way, to quantify the effects of soil-structure interaction on the structural response considering both aleatory and epistemic uncertainties. The goal is achieved by examining the response of established rheological single-degree-of-freedom systems located on shallow-foundation and excited by ground motions with different spectral characteristics. In this regard, four main phases are followed.
First, the effects of seismic soil-structure interaction on the response of structures with linear behaviour are investigated using a robust stochastic approach. Herein, the soil-foundation interface is modelled by an equivalent linear cone model. This phase is mainly considered to examine the influence of soil-structure interaction on the approach that has been adopted in the building codes for developing design spectrum and defining the seismic forces acting on the structure. Second, the effects of structural nonlinearity on the role of soil-structure interaction in modifying seismic structural response are studied. The same stochastic approach as phase 1 is followed, while three different types of structural force-deflection behaviour are examined. Third, a systematic fashion is carried out to look for any possible correlation between soil, structural, and system parameters and the degree of soil-structure interaction effects on the structural response. An attempt is made to identify the key parameters whose variation significantly affects the structural response. In addition, it is tried to define the critical range of variation of parameters of consequent. Finally, the impact of soil-foundation interface nonlinearity on the soil-structure interaction analysis is examined. In this regard, a newly developed macro-element covering both material and geometrical soil-foundation interface nonlinearity is implemented in a finite-element program Raumoko 3D. This model is then used in an extensive probabilistic simulation to compare the effects of linear and nonlinear soil-structure interaction on the structural response.
This research is concluded by reviewing the current design guidelines incorporating soil-structure interaction effects in their design procedures. A discussion is then followed on the inadequacies of current procedures based on the outcomes of this study
Beating the confusion limit: The necessity of high angular resolution for probing the physics of Sagittarius A* and its environment: Opportunities for LINC-NIRVANA (LBT), GRAVITY (VLTI) and and METIS (E-ELT)
The super-massive 4 million solar mass black hole (SMBH) SgrA* shows variable
emission from the millimeter to the X-ray domain. A detailed analysis of the
infrared light curves allows us to address the accretion phenomenon in a
statistical way. The analysis shows that the near-infrared flux density
excursions are dominated by a single state power law, with the low states of
SgrA* limited by confusion through the unresolved stellar background. We show
that for 8-10m class telescopes blending effects along the line of sight will
result in artificial compact star-like objects of 0.5-1 mJy that last for about
3-4 years. We discuss how the imaging capabilities of GRAVITY at the VLTI,
LINC-NIRVANA at the LBT and METIS at the E-ELT will contribute to the
investigation of the low variability states of SgrA*.Comment: 19 pages, 5 figure, Conf. Proc. SPIE Astronomical Telescopes +
Instrumentation 1 - 6 July 2012. Amsterdam No. 8445-
Селянський рух в Харківській губернії (1917–1921 рр.)
Дисертацію присвячено комплексному дослідженню розвитку селянського руху в Харківській губернії в період Української революції 1917–1921 рр. Доведено, що невирішені проблеми у сфері аграрних відносин спричинили селянський рух і розгортання збройного конфлікту на Харківщині у 1917–1921 рр. Порівняно ступінь активної участі у революційних подіях у даному регіоні різних соціальних груп населення. Обґрунтовано тезу, що у період Української революції 1917–1921 рр. представники лівих політичних партій вживали поняття "куркуль" для визначення власників індивідуальних селянських господарств, які бажали зберегти приватну власність на землю й активно захищали свої економічні, політичні та національні права. З'ясовано, що невирішеність національного питання була одним з важливих чинників посилення селянського руху у Харківській губернії. Досліджено взаємозв'язок селянського повстанського руху сусідніх регіонів з селянським рухом у Харківській губернії та встановлено, що найбільш впливовими та популярними серед сільського населення регіону було махновське і "уенерівське" повстанство. Розглянуто процес радикалізації селянського руху у 1917–1921 рр., висвітлено пасивні й активні, нелегальні та легальні форми боротьби селянства за свої економічні, політичні та національні інтереси. Узагальнено наслідки селянського руху
GRAVITY: observing the universe in motion
GRAVITY is the second generation VeryLarge Telescope Interferometer instrument for precision narrow-angle as -trometry and interferometric imaging.With its fibre-fed integrated optics,wavefront sensors, fringe tracker, beamstabilisation and a novel metrologyconcept, GRAVITY will push the sensitivity and accuracy of astrometry andinterferometric imaging far beyond whatis offered today. Providing precisionastrometry of order 10 microarcseconds,and imaging with 4-milliarcsecondresolution, GRAVITY will revolutionisedynamical measurements of celestialobjects: it will probe physics close tothe event horizon of the Galactic Centreblack hole; unambiguously detect andmeasure the masses of black holesin massive star clusters throughout theMilky Way; uncover the details of massaccretion and jets in young stellarobjects and active galactic nuclei; andprobe the motion of binary stars, exoplanets and young stellar discs. Theinstrument capabilities of GRAVITY areoutlined and the science opportunitiesthat will open up are summarised
Non-invasive imaging in the diagnosis of acute viral myocarditis
Autopsy series of consecutive cases have demonstrated an incidence of myocarditis at approximately 1–10%; on the contrary, myocarditis is seriously underdiagnosed clinically. In a traditional view, the gold standard has been myocardial biopsy. However, it is generally specific but invasive and less sensitive, mostly because of the focal nature of the disease. Thus, non-invasive approaches to detect myocarditis are necessary. The traditional diagnostic tools are electrocardiography, laboratory values, especially troponin T or I, creatine kinase and echocardiography. For a long period, nuclear technique with indium-111 antimyosin antibody has been used as a diagnostic approach. In the last years, the use of this technique has declined because of radiation exposure and 48-h delay in obtaining imaging after injection to prevent blood pool effect. Thus, a non-invasive diagnostic approach without radiation and online image availability has been awaited. Cardiac magnetic resonance imaging has these promising characteristics. With this technique, it is possible to analyse inflammation, oedema and necrosis in addition to functional parameters such as left ventricular function, regional wall motion and dimensions. Thus, cardiovascular magnetic resonance imaging has emerged as the most important imaging tool in the diagnostic procedure and the review focus on this field. But there are also advances in echocardiography and computer tomography, which are described in detail
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