An Alternative Method for the Characterisation of Fibrous Materials from Measurements of Absorption Using Techniques Based on the Allard and Champoux Model

2000 ◽  
Vol 31 (8) ◽  
pp. 19-25
Author(s):  
Jesús Alba ◽  
Jaime Ramis
Keyword(s):  
Fibrous Material ◽  
Flow Resistance ◽  
Fibrous Materials ◽  
Specific Flow ◽  
Alternative Method ◽  
Starting Point ◽  
Complete Characterisation ◽  
Absorption Measurements

In this work we present a method for characterising fibrous materials from absorption measurements in the Kundt tube. Specific Flow Resistance may be calculated, using techniques based on the Allard & Champoux model. Using this model and taking measurements of absorption as a starting point, the method presented here enables one to achieve a complete characterisation of a fibrous material.

The Characterisation of Fibrous Materials from Measurements of Absorption Using Techniques Based on Miki's Model

2000 ◽  
Vol 31 (5) ◽  
pp. 14-18
Author(s):  
Jesús Alba ◽  
Jaime Ramis
Keyword(s):  
Fibrous Material ◽  
Flow Resistance ◽  
Fibrous Materials ◽  
Special Equipment ◽  
Specific Flow ◽  
Starting Point ◽  
Complete Characterisation ◽  
Absorption Measurements

In this work the authors present a method for characterizing fibrous materials from absorption measurements in the Kundt tube. Specific Flow Resistance may be calculated, using techniques based on the Miki's model. Using this model and taking measurements of absorption as a starting point, the method presented here enables one to achieve a complete characterisation of a fibrous material, with the added advantage that no special equipment is needed.

scholarly journals The 3D structure of fibrous material is fully restorable from its X-ray diffraction pattern

IUCrJ ◽  
2021 ◽  
Vol 8 (4) ◽  
Author(s):  
Hiroyuki Iwamoto
Keyword(s):  
Diffraction Pattern ◽  
Fibrous Material ◽  
3D Structure ◽  
Wide Field ◽  
Fibrous Materials ◽  
X Ray Diffraction ◽  
X Ray ◽  
Fiber Diffraction ◽  
Puzzle Solving ◽  
Diffraction Patterns

X-ray fiber diffraction is potentially a powerful technique to study the structure of fibrous materials, such as DNA and synthetic polymers. However, only rotationally averaged diffraction patterns can be recorded and it is difficult to correctly interpret them without the knowledge of esoteric diffraction theories. Here we demonstrate that, in principle, the non-rotationally averaged 3D structure of a fibrous material can be restored from its fiber diffraction pattern. The method is a simple puzzle-solving process and in ideal cases it does not require any prior knowledge about the structure, such as helical symmetry. We believe that the proposed method has a potential to transform the fiber diffraction to a 3D imaging technique, and will be useful for a wide field of life and materials sciences.

Investigating the Effects of Fibrous Material Compression on the Acoustical Behavior of Absorption and Barrier Materials

2006 ◽  
Vol 129 (2) ◽  
pp. 133-140 ◽  
Author(s):  
A. R. Ohadi ◽  
M. Moghaddami
Keyword(s):  
Absorption Coefficient ◽  
Fibrous Material ◽  
Transmission Loss ◽  
Element Model ◽  
Physical Parameters ◽  
Fibrous Materials ◽  
Barrier Materials ◽  
Rigid Frame ◽  
Absorbing Materials ◽  
The Galerkin Method

This paper discusses the effects of compression on acoustical performance of fibrous materials. A finite element model is used to predict the absorption coefficient and transmission loss of absorbing and barrier materials. This model is developed based on the Galerkin method and includes the equation of wave propagation in rigid frame porous material. The compression of fibrous material is entered to the model with relations that explain modifications of physical properties used in the wave equation. Acoustical behavior of absorption and barrier materials with and without compression is studied. It is shown that compression of the material leads to reduction of the transmission loss of the barrier materials and absorption coefficient of absorbing materials. In this regard, “thickness reduction” and “variations of physical parameters” due to compression are investigated.

Simple random walk statistics. Part I: Discrete time results

1996 ◽  
Vol 33 (2) ◽  
pp. 311-330 ◽  
Author(s):  
W. Katzenbeisser ◽  
W. Panny
Keyword(s):  
Random Walk ◽  
Random Walks ◽  
Order Statistics ◽  
Discrete Time ◽  
Rank Order ◽  
Simple Random Walk ◽  
Alternative Method ◽  
Starting Point ◽  
Famous Paper ◽  
Rank Order Statistics

In a famous paper, Dwass (1967) proposed a method to deal with rank order statistics, which constitutes a unifying framework to derive various distributional results. In the present paper an alternative method is presented, which allows us to extend Dwass's results in several ways, namely arbitrary endpoints, horizontal steps and arbitrary probabilities for the three step types. Regarding these extensions the pertaining rank order statistics are extended as well to simple random walk statistics. This method has proved appropriate to generalize all results given by Dwass. Moreover, these discrete time results can be taken as a starting point to derive the corresponding results for randomized random walks by means of a limiting process.

The Characterization of Fibrous Material in CVI Graphite Cylinder Wall

2017 ◽  
Vol 904 ◽  
pp. 142-145 ◽  
Author(s):  
Min Yang ◽  
Ming Ming Yu ◽  
Hong Li ◽  
Mu Su Ren ◽  
Jia Bao Zhang ◽  
...  
Keyword(s):  
Fibrous Material ◽  
Chemical Vapor Infiltration ◽  
Laser Raman Spectroscopy ◽  
Main Element ◽  
High Temperature Treatment ◽  
Cylinder Wall ◽  
X Rays ◽  
Fibrous Materials ◽  
Graphite Cylinder

By isothermal chemical vapor infiltration (ICVI) preparation of carbon/carbon composites, We found fibrous materials with silver metallic luster in CVI furnace graphite cylinder outer wall, fiber diameter is 1 ~ 2 mm, length is 4 ~ 15 mm. The characterization of fibrous material have been systematically studied by scanning electron microscopy (SEM),element analysis, energy dispersive X-rays spectroscopy (EDS).After 2300 degrees heat treatment, the fibrous material were characterized by ultra-violet laser Raman spectroscopy. The SEM examination shows that these fibrous materials have a spherical top, the cross-section reveals a unique structure in which layers like growth rings lie concentrically on top of each other. The EDS analysis show the main element of fibrous material is carbon and a small amount of metallic element. Raman spectra show after 2300°C high temperature treatment ,the carbon fibrous material transformed from layer structure to graphite structure.

scholarly journals Influence of the processing method on basic physical and mechanical characteristics of the fibrous material

2020 ◽  
Author(s):  
Roman Marchenko ◽  
Valentina Shurkina
Keyword(s):  
Fibrous Material ◽  
Mechanical Characteristics ◽  
Processing Method ◽  
Fibrous Materials ◽  
Processing Methods ◽  
Physical And Mechanical Characteristics

The article presents a brief analysis of various processing methods for fibrous materials

scholarly journals An Investigation of the Radiative Heat Transfer through Nonwoven Fibrous Materials

2009 ◽  
Vol 4 (1) ◽  
pp. 155892500900400 ◽  
Author(s):  
Imad Qashou ◽  
Hooman Vahedi Tafreshi ◽  
Behnam Pourdeyhimi
Keyword(s):  
Heat Transfer ◽  
Radiative Heat Transfer ◽  
Fibrous Material ◽  
Radiative Heat ◽  
Volume Fraction ◽  
Fiber Diameter ◽  
Solid Volume Fraction ◽  
Surface Radiation ◽  
Fibrous Materials ◽  
Heat Penetration

In this study, the surface-to-surface radiation model of the Fluent CFD code is used to investigate the response of a fibrous material to the radiative heat transfer. The unsteady state heat transfer equation is solved for the temperature and heat flux in and around the fibers that constitute a nonwoven fibrous material. For a fixed fiber diameter, it was shown that the higher the fabric's Solid Volume Fraction (SVF), the slower is the material's average temperature rise. Our simulation results also indicate that for a fixed SVF, fiber diameter has a negligible influence on the unsteady transfer of heat through the media. Of particular interest in this paper is the effect of material's thickness on the heat penetration. It is shown that the transient heat transfer exponentially decreases by increasing the material's thickness for fixed SVFs and fiber diameters. The above finding is also in agreement with our experimental study.

The Characterisation of Fibrous Materials from Measurements of Absorption Using Techniques Based on the Voronina Model

2000 ◽  
Vol 31 (3) ◽  
pp. 14-19
Author(s):  
Jesus Alba ◽  
Jaime Ramis ◽  
Jaime Llinares
Keyword(s):  
Structural Characteristics ◽  
Propagation Constant ◽  
Fibrous Materials ◽  
Special Equipment ◽  
Complex Propagation ◽  
Specific Impedance ◽  
Absorption Measurements

In this work we present a method for characterising fibrous materials from absorption measurements in the Kundt tube. One may calculate the structural characteristics, the complex propagation constant and the specific impedance of material using techniques based on the Voronina Model. Furthermore, this method allows one to estimate the diameter of a fibre for its use in other models, and does not require any special equipment.

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