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Comparative Study of Long- and Short-Stretch Woven Compression Bandages

Aboalasaad Abdelhamid R. R., Sirková Brigita Kolčavová, Bílá Pavlína, Khalil Amany A. S.

Autex Research Journal

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2021

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Vol. 21, no. 4

435--444

EN

Compression therapy using bandages or socks is the most common treatment for venous leg ulcers and edema. This article aims to compare the compression between long- and short-stretch bandages (LSB and SSB, respectively). Load-elongation curves, cyclic loading, and elastic recovery are investigated for both Cotton/Polyamide/Polyurethane and 100% bleached cotton bandages as LSB and SSB, respectively. Static (resting) and dynamic (working) pressures are measured on seven male legs, 31 ± 3.6 years old, using both two and three layers bandaging. Picopress pressure tests are performed on the ankle and mid-calf positions at gradual decreasing compression from the ankle to the knee. The deviation percentage between the experimental results by Picopress and theoretical calculations using Laplace's law and Al-Khaburi equations is compared. LSB recovered approximately 99% of its original length after stress-relaxation whereas SSB recovered only 93% of its original length after 5 days of cyclic load-relaxation. Moreover, SSB lost approximately 28.6% of its activity after wearing on the human leg for 5 days.

2

Energy-based analysis of permanent strain behaviour of cohesive soil under cyclic loading

Sas W., Głuchowski A., Bursa B., Szymański A.

Acta Geophysica

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2017

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Vol. 65, no. 2

331--344

EN

In this paper the original results of uniaxial cyclic compression test on cohesive soil are presented. The shakedown phenomena in cohesive soil are described. Energy-based method highlights the change of soil material behaviour from plastic shakedown through plastic creep shakedown to incremental collapse. The samples were cyclically loaded under undrained conditions with the constant amplitude of stress in one-way test procedure. In this study the energy-based method was presented as a proper method to categorise response of cohesive soil to cyclic loading in uniaxial conditions. A shakedown criterion factor, SE, was introduced to help understand the shakedown phenomena in cohesive soil. In cohesive soils the absence of a limit between plastic shakedown and plastic creep shakedown was pointed out.

3

An improved Neural Kalman Filtering Algorithm in the analysis of cyclic behaviour of concrete specimens

Krok A.

Computer Assisted Mechanics and Engineering Sciences

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2011

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Vol. 18, no. 4

275-282

EN

The article is related to the results of research on Node Decoupled Extended Kalman Filtering (NDEKF) as a learning method for the training of Multilayer Perceptron (MPL). Developments of this method made by the author are presented. The application of NDEKF and MPL and other methods (pruning of MLP, Gauss Process model calibrated by Genetic Algorithm and Bayesian learning methods) are discussed on the problem of hysteresis loop simulations for tests of compressed concrete specimens subjected to cyclic loading.

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Influence of loading history on the cervical screw pullout strength value

Pezowicz C., Filipiak J.

Acta of Bioengineering and Biomechanics

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2009

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Vol. 11, nr 3

35-40

EN

The problem of the loosening and pullout of bone screws in cervical spine stabilisation is a significant factor in failed implantations of that spine region. Therefore, studies were undertaken to determine the impact of the loading history of bone screws of the cervical spine, inserted from the anterior approach, on the stability of the screw-bone interface. The research was conducted on vertebrae obtained from cadaver specimens of the cervical spine. Two screws were inserted into each vertebra and then pulled out with a force acting along the screw axis. The mean pullout force for the screws subjected to cyclic preloading was 355.2 +- 74.4 N, and for the screws subjected to direct pullout it was 411.0 +- 78 N (p<0.05). The research results show a significant impact of bone tissue preloading with a cyclic variable force on the pullout force obtained. For the preloaded bone screws the recorded rupture strength of the implant-vertebral body interface was by 16% lower compared to the screws pulled out without preloading. The values presented also show a strong correlation between the bone density and the pullout force obtained after cyclic loading with the strength normal to the screw axis.