scholarly journals STANDING WAVES IN ENGINEERING OBJECTS OF COMPLEX CONSTRUCTIONS

2019 ◽  
Vol 2 (2) ◽  
pp. 67-73
Author(s):  
Alexander Emanov ◽  
Alexander Bach
Keyword(s):  
Complex Geometry ◽  
Block Structure ◽  
Standing Waves ◽  
Coupled Resonators ◽  
Natural Oscillations ◽  
Standing Wave Method ◽  
Seismic Oscillations ◽  
Complex Engineering ◽  
Verification Of Models ◽  
Common Field

According to the results of research on complex engineering objects, results were obtained that demonstrate significant deviations from the models of buildings and structures adopted as the basis for calculating seismic resistance and structural stability. First, it is the existence of reflecting seismic oscillations of the boundaries inside the building, when standing waves form a common field for the building as a whole and a local field for a part of the object. Secondly, a block structure of the object, when there are natural oscillations of different magnification with a different area of the object's coverage, when some blocks independently oscillate, they unite into one system. Thirdly, the existence of walls with double reflecting properties, which changes the field of standing waves. Fourthly, the complex geometry of the object causes fields of standing waves, e is described by two wave numbers. Experimental data show that in the theory of buildings, it is necessary to move to the models of nested resonators, models of coupled resonators, and the verification of models should be entrusted to the standing wave method.

Methods of detectiоn a voids under concrete slabs of water faces of the dam of Novosibirsk hydrostation by the standing wave method

2020 ◽  
Author(s):  
Konstantin V. Fedin ◽  
◽  
Yury I. Kolesnikov ◽  
Luckymore Ngomayezwe ◽  
◽  
...  
Keyword(s):  
Standing Wave ◽  
Acoustic Noise ◽  
Standing Waves ◽  
Hydraulic Structures ◽  
Concrete Slabs ◽  
Wave Method ◽  
Compression Waves ◽  
Standing Wave Method ◽  
Amplitude Spectra ◽  
Base Soil

Using the example of the Novosibirsk hydrostation, the capabilities of the standing wave method to identify defects in the fastenings of water faces of dams of hydraulic structures are demonstrated. The accumulation of amplitude spectra of acoustic noise records allows one to determine the frequencies of the few first modes of standing compression waves generated by noise in concrete slabs. A sharp increase in the frequency of the lowest mode of standing waves is an indicator of the appearance of voids under the slabs or decompression of the base soil.

scholarly journals Verification of a design model and evaluation of a technique of manufacturing aircraft engine composite parts on the basis of dynamic tests

2020 ◽  
Vol 18 (4) ◽  
pp. 52-63
Author(s):  
A. V. Zinin ◽  
A. N. Arkhipov ◽  
D. P. Kholobtsev ◽  
Yu. A. Ravikovich ◽  
A. O. Shevjakov ◽  
...  
Keyword(s):  
Experimental Evaluation ◽  
Complex Geometry ◽  
Aircraft Engine ◽  
Design Model ◽  
Natural Oscillations ◽  
Local Characteristics ◽  
Damped Oscillations ◽  
Thin Walled ◽  
Effective Design

The results of finite element modeling and experimental evaluation of dynamic characteristics (vibration modes and frequencies) of the composite element of aircraft power plant structures are presented. The aim of the work is to develop effective design and technological schemes for thin-walled complex-geometry composite parts, taking into account the peculiarities of mechanical behavior of polymer composite materials to the fullest extent possible. A method for determining the parameters of natural oscillations of composite parts in a free state using a ping test is developed, which allows excluding the influence of kinematic boundary conditions and obtaining frequency characteristics that depend only on the local characteristics of the material which are primarily determined by the manufacturing technology. According to the results of measurements of the amplitude-frequency parameters of the dynamic response, spectrograms of damped oscillations are obtained the peak values of which correspond to the experimental evaluation of the natural frequencies of the composite part. Verification of the design model was carried out according to the results of the ping test and a method for assessing the quality of technological processes of manufacturing thin-walled carbon fiber structures was proposed.

scholarly journals FEATURES OF SEASONAL CHANGES OF THE FIELD OF STANDING WAVES IN THE DAM OF THE CHIRKEY HPP

2019 ◽  
Vol 2 (3) ◽  
pp. 3-10
Author(s):  
Aleksei Liseikin ◽  
Victor Seleznev ◽  
Zarahman Adilov
Keyword(s):  
Standing Wave ◽  
Experimental Work ◽  
Seasonal Changes ◽  
Standing Waves ◽  
Technical Condition ◽  
Arch Dam ◽  
Natural Oscillations ◽  
Wave Fields

The natural oscillations of the arch dam of the Chirkey HPP, isolated from the microseismic background by the method of coherent recovery of standing wave fields, are analyzed. Experimental work was carried out twice - at the maximum and minimum filling levels of the reservoir. This made it possible to identify the features of seasonal changes in the field of standing waves. The results can be used to monitor the technical condition of the Chirkey dam.

EXCITATION OF FREAK WAVE BY NATURAL OSCILLATIONS OF THE WATER BODY

2021 ◽  
pp. 106-114
Author(s):  
P. V. Anakhov
Keyword(s):  
Spatial Structure ◽  
Linear Theory ◽  
Water Body ◽  
Standing Waves ◽  
Dam Break ◽  
Extreme Waves ◽  
Natural Oscillations ◽  
Freak Waves ◽  
Freak Wave ◽  
Fixed Period

In linear theory the formation of extreme waves their existence is interpreted as a local superposition of surface monochromatic waves. Natural water areas are resonators that have their own set of natural oscillations – standing waves of stable spatial structure and fixed period. In the spectra of waves of many water bodies of World Ocean observed double high waves, this is explained by the tidal-seiche resonance. During a storm, the energy of natural oscillations increases ten times the background energy, during a tsunami it can increase up to three orders of magnitude. Examples of the effects of natural oscillations on the coast are given, and it is reported about the increased probability of the occurrence on the coast freak waves. Additionally, it is noted that natural oscillations in water mass are a normal state for any body of water at any time of its existence. The corresponding indices of the water fluctuations of the water basins are given. The events of extreme waves during the accidents at DniproHES (Zaporizhia) on August 18, 1941, and the Kurenivsky dam (Kyiv) on March 13, 1961, are presented. The excitement of the freak wave can be interpreted as enhancing the natural oscillations of the water basin, represented by standing waves of stable spatial structure, fixed period and high probability of waves in the water body. This does not contradict the linear theory of the resonant formation of abnormally high waves. The purpose of the article is to investigate possible sources of the excitement of freak waves, the results are proposed to be implemented in the development of countermeasures to the destructive process. However, the waves carry out both destructive and creative work. A task is presented, which involves the development of measures to stimulate extreme waves. This will increase electricity generation. Affiliation of dam-break waves to freak waves can be doubtful. However, they formally correspond to the classical condition of double exceeding the significant wave height. Most water basins are integral anthropogenic sites. The variability of both natural and anthropogenic environments forces the overriding of systematization and definition. It is proposed to attribute extreme waves of dam-break waves to freak waves.

scholarly journals Features of the monitoring of natural frequencies of hydro power plant dams (on the example of the Chirkey dam)

2019 ◽  
Vol 1 (1) ◽  
pp. 23-34
Author(s):  
Aleksei Liseikin ◽  
Viktor Seleznev ◽  
Zarakhman Adilov ◽  
Ting-Yu Hsu ◽  
Valentino Arygianni
Keyword(s):  
Power Plant ◽  
Natural Frequencies ◽  
Standing Waves ◽  
Relaxation Processes ◽  
Base System ◽  
Observation Data ◽  
Natural Oscillations ◽  
Hydro Power ◽  
Factors Affecting ◽  
Definition Of

A method is proposed for monitoring the natural frequencies of hydro power plant dams using continuous seismic observation data. The object of the research is the largest in Russia arched Chirkey dam located in the Caucasus. At the initial stage, a detailed study of the natural oscillations of the dam was performed using the method of coherent restoration of the standing wave fields with the definition of both the natural frequencies of the structure and their modes. The features of seasonal changes in the total field of standing waves are studied and factors affecting changes in natural frequencies are established. At the next stage, the values of natural frequencies were determined from the spectra of microseismic oscillations recorded by seismic equipment installed on the object. Observation points located in the antinodes of standing waves were used. The values of the natural frequencies of the Chirkey dam, as a whole, decrease with increasing upstream level. It was determined that there are additional factors leading to the hysteresis effect in the relationship between the values of the upstream level and natural frequencies, presumably associated with relaxation processes in the dam body and/or in the dam-base system after the change of level. A method for monitoring the state of the dam is proposed, based on a comparison of the observed values of natural frequencies with the predicted ones. The latter are determined by linear dependencies on the upstream level, taking into account the time shifts associated with relaxation processes

The Moving-IAT

2017 ◽  
Vol 33 (6) ◽  
pp. 445-452
Author(s):  
Monika Fleischhauer
Keyword(s):  
Internal Consistency ◽  
Personality Assessment ◽  
Block Structure ◽  
Mental Representations ◽  
Indirect Measures ◽  
Attitude Research ◽  
Self Reports ◽  
Implicit Personality ◽  
Single Block ◽  
Psychometric Quality

Abstract. Accumulated evidence suggests that indirect measures such as the Implicit Association Test (IAT) provide an increment in personality assessment explaining behavioral variance over and above self-reports. Likewise, it has been shown that there are several unwanted sources of variance in personality IATs potentially reducing their psychometric quality. For example, there is evidence that individuals use imagery-based facilitation strategies while performing the IAT. That is, individuals actively create mental representations of their person that fit to the category combination in the respective block, but do not necessarily fit to their implicit personality self-concept. A single-block IAT variant proposed by attitude research, where compatible and incompatible trials are presented in one and the same block, may prevent individuals from using such facilitation strategies. Consequently, for the trait need for cognition (NFC), a new single-block IAT version was developed (called Moving-IAT) and tested against the standard IAT for differences in internal consistency and predictive validity in a sample of 126 participants. Although the Moving-IAT showed lower internal consistency, its predictive value for NFC-typical behavior was higher than that of the standard IAT. Given individual’s strategy reports, the single-block structure of the Moving-IAT indeed reduces the likelihood of imagery-based strategies.

Matching Design of Tram Flexible Block Structure and Material

CICTP 2020 ◽  
2020 ◽  
Author(s):  
Wanqing Zhang ◽  
Jinyan Zhu ◽  
Ying Cheng ◽  
Chen Liu ◽  
Rongchun Shi
Keyword(s):  
Block Structure ◽  
Matching Design

On everyday academic research

2017 ◽  
pp. 98-134 ◽  
Author(s):  
J. Tirole
Keyword(s):  
Common Good ◽  
Academic Research ◽  
Research Quality ◽  
Economic Research ◽  
Relevant Research ◽  
The Common ◽  
Verification Of Models ◽  
Science And Research

In the fourth chapter of the book “The economy of the common good”, the nature of economics as a science and research practices in their theoretical and empirical aspects are discussed. The author considers the processes of modeling, empirical verification of models and evaluation of research quality. In addition, the features of economic cognition and the role of mathematics in economic research are analyzed, including the example of relevant research in game theory and information theory.

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