Acceleration waves on random fields with fractal and Hurst effects

Nishawala, Vinesh V.; Ostoja–Starzewski, Martin

doi:10.1016/j.wavemoti.2017.07.004

Cited by 13 publications

(7 citation statements)

References 11 publications

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“…To model the said RFs, we work with second-order, wide-sense stationary and isotropic models having Cauchy or Dagum correlation (covariance) functions [2,3], which do not automatically presuppose any self-affinity. Such fields have already been employed in one-dimensional spatial settings and random process loadings [4]. Here, we continue our investigations in the setting of two-dimensional RFs of mass density with such characteristics and, as a stepping-stone, we use two recent studies:…”

Section: Introductionmentioning

confidence: 99%

Impact force and moment problems on random mass density fields with fractal and Hurst effects

Zhang

Ostoja–Starzewski

2020

Phil. Trans. R. Soc. A.

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This paper reports the application of cellular automata to study the dynamic responses of Lamb-type problems for a tangential point load and a concentrated moment applied on the free surface of a half-plane. The medium is homogeneous, isotropic and linear elastic while having a random mass density field with fractal and Hurst characteristics. Both Cauchy and Dagum random field models are used to capture these effects. First, the cellular automata approach is tested on progressively finer meshes to verify the code against the continuum elastodynamic solution in a homogeneous continuum. Then, the sensitivity of wave propagation on random fields is assessed for a wide range of fractal and Hurst parameters. Overall, the mean response amplitude is lowered by the mass density field’s randomness, while the Hurst parameter (especially, for β < 0.2) is found to have a stronger influence than the fractal dimension on the response. The resulting Rayleigh wave is modified more than the pressure wave for the same random field parameters. Additionally, comparisons with previously studied Lamb-type problems under normal in-plane and anti-plane loadings are given. This article is part of the theme issue ‘Advanced materials modelling via fractional calculus: challenges and perspectives’.

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Section: Introductionmentioning

confidence: 99%

Impact force and moment problems on random mass density fields with fractal and Hurst effects

Zhang

Ostoja–Starzewski

2020

Phil. Trans. R. Soc. A.

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“…e H can be used as an index to judge whether time-series data follow a random walk or a biased random walk [22]. Because this index cannot adequately indicate the changes in chaos of radiotelephony communication, this paper illustrates how the chaos in a speech signal changes the presence of fatigue from a different aspect.…”

Section: Chaos In a Speech Signalmentioning

confidence: 99%

A High-Precision Fatigue Detecting Method for Air Traffic Controllers Based on Revised Fractal Dimension Feature

Shen

Pan

Yan

2020

Mathematical Problems in Engineering

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As air traffic volume increases, the air traffic controller (ATC) fatigue has become a major cause for air traffic accidents. However, the conventional fatigue-detecting methods based on speech are neither effective nor accurate because the speech signals are nonlinear and complicated. In this paper, an ATC fatigue-detecting method based on fractal dimension (FD) is proposed. Firstly, a special speech database of ATC radiotelephony communications is constructed. These radiotelephony communications are obtained from Air Traffic Management Shandong Bureau of China. Then, speech signals implement a wavelet decomposition and FD calculation. The calculation result shows the significant difference among the FD of the speech signal before and after fatigue. Furthermore, a novel fatigue feature of the ATC based on the FD of speech is built. A series of experiments are conducted to detect the ATC fatigue with the fatigue feature comparison process and a support vector machine (SVM). The results show that the accuracy in detecting ATC fatigue based on FD was 92.82%, which are higher than the state-of-the art methods. The research provides a theoretical guidance for Air Traffic Management Authority on detecting ATC’s fatigue, while it may provide reference for the fatigue assessment in other professional fields of civil aviation.

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“…Неопределенность процессов, происходящих в биосфере Неопределенность процессов, происходящих на Земле, в биосфере и других геосферах, в сфере синтеза, перераспределения и возобновления энергии, во многом обусловлена недостатком информации, поскольку постоянно протекающие, во многом фрактальные, явления описывают отдельными наблюдениями, качество которых для создания образа реального объекта может быть критически дефектным. На это накладываются волны многомасштабной акселерации статистических полей, наблюдается эффект Харста, в результате усиливается девиация параметров системы по сравнению со случаем, если её рассматривать как гомогенную монотонную Nishawala & Ostoja-Starzewski, 2017). Это усиливает вероятность проявления положительных обратных связей между парциальными явлениями в геосферах, обусловливает их дестабилизацию, формируется неустойчивый мир.…”

Section: биотехнологияunclassified

Renewal of Energy and Life in the Biosphere

2017

European Journal of Renewable Energy

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Energy renewal should be oriented not so much on a human who is the energy main consumer, but in the first turn on the Earth's geospheres. The properties of sources, fluxes and sinks of energy are considered in focus of energy consumer, and, simultaneously, in focus of an object to which the consumer belongs concerning creating a long-term priority human living conditions and providing buffer parameters for geospheres. The evolution of the biosphere and the pedosphere is considered, the significance of the use and renewal of hydrocarbon energy in the Earth's biogeochemical cycle is shown. Demand for energy on Earth is considered in the focus of the current conflict "technology -consumption -ecosphere" as a result of an incorrect strategy of technological development within the framework of outdated industrial technological platform. To increase the application of renewal energy on Earth is possible due to optimization of the biogeochemical cycle, improving the quality of the biosphere, improving living conditions, motivating the use of energy. Biogeosystem Technique is proposed as a new scientific and technical platform for strategic development of the world and its technology, organically connected with the problem of production and use of renewal energy on Earth. Biogeosystem Technique instead of direct imitation of natural phenomena suggests the use of development opportunities that Nature leaves to man as a productive way to understand the Nature's intent and use it for harmonious development, but not to resist Nature. Biogeosystem Technique provides: design of long-term resistant high-fertility soils by milling the layer of 20-45 cm, which increases biological productivity by 30-50 % for a period of up to 40 years; soil watering without the infiltration of water by a pulse injection through the slide syringe element directly into a discrete volume of soil of 2-3 cm diameter to a depth from 10 to 40 cm, that provides fresh water saving in comparison with standard irrigation methods from 3 to 20 times, soil conservation, a stable biogeochemical barrier "soil -root system"; recycling of industrial, domestic, agricultural, biological waste (including dangerous due to possibility to break the trophic distribution chains, including gasification waste) in the intra-soil milling and intra-soil watering for fertilizing and improving soil, avoiding food contamination. The way for expanding biosphere and increasing its product is opened up through expanding the biological and soil phase of the carbon biogeochemical cycle, enhancing ionization of air in photosynthesis and precipitating aerosols, obtaining additional food, raw materials, biofuels,

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Acceleration waves on random fields with fractal and Hurst effects

Cited by 13 publications

References 11 publications

Impact force and moment problems on random mass density fields with fractal and Hurst effects

Impact force and moment problems on random mass density fields with fractal and Hurst effects

A High-Precision Fatigue Detecting Method for Air Traffic Controllers Based on Revised Fractal Dimension Feature

Renewal of Energy and Life in the Biosphere

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