An Acoustic-Microwave Method for the Study of the Mechanical Influence of Moisture Content in Materials

2003 ◽  
Vol 70 (2) ◽  
pp. 268-274 ◽  
Author(s):  
C. Bacon ◽  
E. Guilliorit ◽  
B. Hosten
Keyword(s):  
Moisture Content ◽  
Acoustic Waves ◽  
Viscoelastic Properties ◽  
Medium Density Fiberboard ◽  
Microwave Method ◽  
One Dimensional ◽  
Electromagnetic Absorption ◽  
Absorbing Materials ◽  
Viscoelastic Characteristics ◽  
Mechanical Influence

A one-dimensional theoretical model is developed to predict the acoustic waves generated by rapid thermal expansion caused by electromagnetic microwave absorption in viscoelastic rods. The theoretical acceleration at the end of the irradiated rod is predicted. The comparison between the experimental and the theoretical accelerations leads to the evaluation of viscoelastic characteristics. Parameters related to the electromagnetic absorption can be also obtained. A procedure to find approximate values of the different parameters is developed. Since it is considered in the model that the distribution of the temperature rise along the rod is exponential, very absorbing materials can be tested. Consequently, the influence of the moisture content on viscoelastic properties of a porous material can be investigated. The method is applied to study the influence of the moisture content on viscoelastic characteristics of medium density fiberboard materials.

The influence of osteopathic correction on the viscoelastic characteristics of the lower leg muscles

2019 ◽  
pp. 93-98
Author(s):  
E. M. Timanin ◽  
N. S. Sydneva ◽  
A. A. Zakharova
Keyword(s):  
Viscoelastic Properties ◽  
Gastrocnemius Muscle ◽  
Soft Tissues ◽  
Subjective Assessment ◽  
Lymphatic Drainage ◽  
Intercellular Substance ◽  
Leg Muscles ◽  
Before And After ◽  
Viscoelastic Characteristics ◽  
Instrumental Methods

Introduction. To date there is a lack of studies dedicated to the objectification of the palpation data obtained by a specialist during the osteopathic examination. The issue of the evidence of the results of osteopathic correction still remains important. Search for instrumental methods allowing to register and to measure various palpation phenomena and manifestations of somatic dysfunctions is very relevant for the development of osteopathy as a science. It is also very important to find objective characteristics of these methods.Goal of research — to study viscoelastic characteristics of the soft tissues of the lower legs by palpation and instrumental methods before and after osteopathic correction.Materials and methods. 22 volunteers (12 women and 10 men) aged 18–23 years without complaints of the musculoskeletal system were examined. Osteopathic diagnostics and measurement of the viscoelastic properties of muscles were carried out by the method of vibration viscoelastometry before and after osteopathic correction.Results. Correlation analysis by Spearman showed that the subjective assessment of an osteopath positively correlated with both elasticity (r=0,43, p<0,05) and viscosity of soft issues (r=0,29, p<0,05). For the gastrocnemius muscle, this pattern was even more pronounced — for elasticity r=0,51, p<0,05, for viscosity =0,34, p<0,05. After osteopathic correction no changes in the elasticity of the soft tissues were observed. The viscosity of the tissues reduced, but in the projection of the gastrocnemius muscle, these changes were not statistically significant (p=0,12), whereas in the projection of the soleus muscle statistically significant changes (p=0,034) were observed.Conclusion. Changes in the viscoelastic properties of tissues demonstrated that the effects of osteopathic correction with the use of myofascial mobilization techniques, articulation mobilization techniques, and lymphatic drainage techniques were not obvious. The elasticity of soft tissues of the lower legs did not change, while the viscosity decreased, especially in the projection of the soleus muscles. This effect of the osteopathic correction can be associated with the effect of thixotropy — the transformation of gel-like intercellular substance into sol. Thus, the research showed that vibration viscoelastometry can be used for the objectifi cation of the condition of soft tissues and of the effects of osteopathic correction.

scholarly journals Resonant excitation of acoustic waves in one-dimensional exciton-polariton systems

2019 ◽  
Vol 100 (4) ◽  
Author(s):  
A. V. Yulin ◽  
V. K. Kozin ◽  
A. V. Nalitov ◽  
I. A. Shelykh
Keyword(s):  
Acoustic Waves ◽  
Resonant Excitation ◽  
One Dimensional

One-dimensional acoustic waves in retarding structures with propagation velocity tending to zero

2002 ◽  
Vol 48 (3) ◽  
pp. 347-352 ◽  
Author(s):  
M. A. Mironov ◽  
V. V. Pislyakov
Keyword(s):  
Acoustic Waves ◽  
Propagation Velocity ◽  
One Dimensional

scholarly journals Energetic characterization and radiographic analysis of torrefied coated MDF residues

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Paula Gabriella Surdi de Castro ◽  
Vinícius Resende de Castro ◽  
Antonio José Vinha Zanuncio ◽  
José Cola Zanuncio ◽  
Angélica de Cássia Oliveira Carneiro ◽  
...  
Keyword(s):  
Moisture Content ◽  
Energy Production ◽  
Medium Density Fiberboard ◽  
Volatile Matter ◽  
Density Variation ◽  
Low Oxygen ◽  
Wood Panel ◽  
X Ray ◽  
Energetic Characterization ◽  
Elementary Chemical

AbstractThe use of wood panel residues as biomass for energy production is feasible. Heat treatments can improve energy properties while minimizing the emission of toxic gases due to thermoset polymers used in Medium Density Fiberboard (MDF) panels. Torrefaction or pre-carbonization, a heat treatment between 200 and 300 °C with low oxygen availability accumulates carbon and lignin, decreases hygroscopicity, and increases energy efficiency. The objective of this work was to evaluate the energy parameters (immediate, structural, and elementary chemical composition, moisture content, and yield) and density in torrefied MDF panels. The torrefaction improved the energetic features of coated MDF, decreasing the moisture content, volatile matter, and consequently, concentrating the carbon with better results in the samples torrefied for 40 min. The densitometric profiles of the torrefied MDF, obtained by X-ray densitometry, showed a decrease in the apparent density as torrefaction time increased. The digital X-ray images in gray and rainbow scale enabled the most detailed study of the density variation of MDF residues.

scholarly journals Wave Propagation in Thin-Walled Aortic Analogues

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
C. G. Giannopapa ◽  
J. M. B. Kroot ◽  
A. S. Tijsseling ◽  
M. C. M. Rutten ◽  
F. N. van de Vosse
Keyword(s):  
Experimental Data ◽  
Wave Propagation ◽  
Frequency Domain ◽  
Analytical Model ◽  
Viscoelastic Properties ◽  
Numerical Models ◽  
Computational Cost ◽  
One Dimensional ◽  
Arterial Blood

Research on wave propagation in liquid filled vessels is often motivated by the need to understand arterial blood flows. Theoretical and experimental investigation of the propagation of waves in flexible tubes has been studied by many researchers. The analytical one-dimensional frequency domain wave theory has a great advantage of providing accurate results without the additional computational cost related to the modern time domain simulation models. For assessing the validity of analytical and numerical models, well defined in vitro experiments are of great importance. The objective of this paper is to present a frequency domain analytical model based on the one-dimensional wave propagation theory and validate it against experimental data obtained for aortic analogs. The elastic and viscoelastic properties of the wall are included in the analytical model. The pressure, volumetric flow rate, and wall distention obtained from the analytical model are compared with experimental data in two straight tubes with aortic relevance. The analytical results and the experimental measurements were found to be in good agreement when the viscoelastic properties of the wall are taken into account.

High-frequency single-electron transport in a quasi-one-dimensional GaAs channel induced by surface acoustic waves

1996 ◽  
Vol 8 (38) ◽  
pp. L531-L539 ◽  
Author(s):  
J M Shilton ◽  
V I Talyanskii ◽  
M Pepper ◽  
D A Ritchie ◽  
J E F Frost ◽  
...  
Keyword(s):  
Electron Transport ◽  
Acoustic Waves ◽  
High Frequency ◽  
Surface Acoustic Waves ◽  
Single Electron ◽  
One Dimensional ◽  
Single Electron Transport

Zener tunneling of acoustic waves in a one-dimensional phononic crystal

2007 ◽  
Vol 144 (10-11) ◽  
pp. 433-436 ◽  
Author(s):  
Zhaojian He ◽  
Shasha Peng ◽  
Yun Wang ◽  
Manzhu Ke ◽  
Zhengyou Liu
Keyword(s):  
Acoustic Waves ◽  
Phononic Crystal ◽  
One Dimensional ◽  
Zener Tunneling

One-dimensional consolidation of multilayered aquifer systems with viscoelastic properties induced by time-dependent groundwater drawdown

2021 ◽  
pp. qjegh2021-073
Author(s):  
Weitao Yang ◽  
Jin Xu
Keyword(s):  
Viscoelastic Properties ◽  
Numerical Solutions ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Time Dependent ◽  
Analytical Models ◽  
Consolidation Process ◽  
One Dimensional ◽  
Groundwater Drawdown ◽  
Aquifer Systems

Most analytical and semi-analytical models for pumping-induced land subsidence invoke the simplifying assumptions regarding characteristics of geomaterials, as well as the pattern of drawdown response to pumping. This paper presents an analytical solution for one-dimensional consolidation of the multilayered soil due to groundwater drawdown, in which viscoelastic property and time-dependent drawdown are taken into account. The presented solution is developed by using the boundary transformation techniques. The validity of the proposed solution is verified by comparing with a degenerated case for a single layer, as well as with the numerical solutions and experimental results for a two-layer system. The difference between the average consolidation degree Up defined by hydraulic head and that Us defined by total settlement is discussed. The detailed parametric studies are conducted to reveal the effects of viscoelastic properties and drawdown patterns on the consolidation process. It is revealed that while the effect of different drawdown response patterns is significant during the early-intermediate stages of consolidation, the viscoelastic properties may have a more dominant influence on long-term consolidation behavior, depending on the values of the material parameters, which are reflected in both the deformation process of soil layers and the dissipation of excess pore-water pressure.

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