scholarly journals Relationships between the Macrostructure Features and Acoustic Parameters of Resonance Spruce for Piano Soundboards

2021 ◽  
Vol 11 (4) ◽  
pp. 1749
Author(s):  
Ginevra Manzo ◽  
Jan Tippner ◽  
Petr Zatloukal
Keyword(s):  
Sound Velocity ◽  
Cross Section ◽  
Acoustic Radiation ◽  
Longitudinal Direction ◽  
Acoustic Properties ◽  
Mode Shapes ◽  
Strong Correlations ◽  
Acoustic Parameters ◽  
Radiation Coefficient ◽  
The Cross

An experimental examination of the relationship between the macrostructure characteristics and the acoustic properties of Norway spruce was performed. The macrostructure features were found to comprise the density (ρ), percentage of latewood (%LW), slope of grain (α), and angle the annual rings in a cross section (β). The main acoustic parameters of the research were the sound velocity, dynamic Young’s modulus, acoustic impedance (Z), and radiation coefficient (R). The acoustic properties for both the cross section and the longitudinal direction were calculated. Non-destructive evaluation (NDE) is the appropriate approach to define acoustic properties. Ultrasonic direct transmission and a transitory excitation method were used to calculate and compare the acoustic properties. A modal analysis was performed to predict the frequency range that corresponded to the different mode shapes. There were no significant differences between the two methods, yet an 80% reduction of the velocity, Z and R was identified between the longitudinal direction and the cross section. The equations used to define acoustic radiation according to the latewood component were defined, and strong correlations between the macrostructure and acoustic parameters were confirmed. A tight relationship was observed between the reduction of sound velocity and material density exceeding 440 kg m−3.

The Anticlastic Curvature of a Strip With Lateral Thickness Variation

1954 ◽  
Vol 21 (4) ◽  
pp. 351-358
Author(s):  
Y. C. Fung ◽  
W. H. Wittrick
Keyword(s):  
Cross Section ◽  
Large Deflection ◽  
Longitudinal Direction ◽  
Middle Surface ◽  
Thickness Variation ◽  
Double Wedge ◽  
Wedge Shape ◽  
The Cross ◽  
Anticlastic Curvature ◽  
Plates Of Variable Thickness

Abstract The large deflection equations of von Kármán have been extended to apply to plates of variable thickness with initial deviations of the middle surface from a plane. These are used to determine the distortion of the cross section of a strip with lateral thickness variation, when bent uniformly in the longitudinal direction. Numerical calculations are made for the case of a strip whose cross section is of double-wedge shape and it is shown that when the longitudinal curvature becomes large the distortion of the cross section is quite different from that of a strip of uniform thickness.

Hybridizing semianalytical and conventional finite-element schemes for simulations of electromagnetic borehole resistivity measurement

Geophysics ◽  
2017 ◽  
Vol 82 (1) ◽  
pp. E17-E26 ◽  
Author(s):  
Jiefu Chen ◽  
Shubin Zeng
Keyword(s):  
Finite Element ◽  
Finite Elements ◽  
Cross Section ◽  
Resistivity Measurement ◽  
Longitudinal Direction ◽  
Integration Scheme ◽  
The Cross ◽  
Semianalytical Method ◽  
Resistivity Logging ◽  
Finite Element Schemes

A semianalytical finite-element method (FEM) has been developed to simulate electromagnetic borehole resistivity measurements in a layered underground formation. A piecewise homogeneous structure is divided into several layers. Each layer is uniform in the longitudinal direction, and the distributions of geometry and material can be arbitrary on the transverse plane, or cross section, of the layer. To develop this semianalytical finite-element scheme, the standard functional corresponding to the vector wave equation is cast to a new form in the Hamiltonian system based on dual variables that are the transverse components of electric and magnetic fields on the cross section of the layer. The 2D finite elements are used to discretize the cross section, and a high-precision integration scheme based on the Riccati equations is used to exploit the longitudinal homogeneity in the layer. By transforming a 3D layered problem into a series of 2D problems, this semianalytical FEM can save a great amount of computational costs and meanwhile achieve a higher level of accuracy when compared with conventional finite-element schemes. The flexibility of this semianalytical method can be greatly increased by hybridization with conventional finite elements, and this strategy works well for layered structures with local inhomogeneities such as borehole washouts. Several tests, including near-bit resistivity measurement and wave propagation resistivity logging, verified the effectiveness of this semianalytical FEM.

The Acoustic and Structural Properties of the Human Femur

1998 ◽  
Vol 120 (1) ◽  
pp. 71-76 ◽  
Author(s):  
S. Weiss ◽  
M. C. Zimmerman ◽  
R. D. Harten ◽  
F. G. Alberta ◽  
A. Meunier
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Acoustic Impedance ◽  
Acoustic Property ◽  
Moment Of Inertia ◽  
The Other ◽  
Acoustic Properties ◽  
Human Femur ◽  
Principal Moments Of Inertia ◽  
The Cross

This study evaluates the variations in the acoustic properties of the human femur at ten evenly spaced locations along its length, as well as differences that exist within given transverse sections. Six pairs of human femora, three male and three female, were sectioned, ground, and polished, and scanned with a microprocessor-driven scanning acoustic microscope. Images with a resolution of approximately 140 μm were used to calculate the average acoustic impedances for each transverse cross section and each quadrant within a cross section. The mean acoustic impedance for all the cross sections was 7.69 ± 0.18 Mrayls. Variations were observed among the cross sections, and the central sections (4–7) had values that were statistically greater than the other more distal and proximal sections. Within the cross sections, the posterior quadrant had a lower average acoustic impedance compared to the other quadrants and this was statistically significant (Tukey’s multiple comparison test). The cross sections were further analyzed to determine several geometric parameters including the principal moments of inertia, polar moment of inertia, and the biomechanical shape index. The product of the acoustic impedance and the maximum moment of inertia provided a result that attempted to account for the acoustic property variation and the change in shape at the different section locations.

scholarly journals A new approach to the identification of distortion modes of thin-walled structures based on plate/shell theory

2019 ◽  
Vol 278 ◽  
pp. 03005
Author(s):  
Lei Zhang ◽  
Weidong Zhu ◽  
Aimin Ji ◽  
Liping Peng
Keyword(s):  
Cross Section ◽  
Shell Theory ◽  
Mode Shapes ◽  
Beam Model ◽  
Linear Superposition ◽  
New Approach ◽  
Thin Walled Structures ◽  
Dynamic Analyses ◽  
Thin Walled ◽  
The Cross

In this paper, a new approach to identify cross-section deformation modes is presented and utilized in the establishment of a high-order beam model for dynamic analyses of thin-walled structures. Towards this end, a systematic procedure to extract cross-section in-plane vibration shapes for a thin-walled cross-section is developed based on elastic plate/shell theory. Then the distortion shapes are separated from vibration shapes by removing the components of classic modes involved with the minimum value problem of 2-norm. Sequentially, curve fitting method is utilized to approximate the distortion shape functions along the cross-section midline. It should be noticed that these distortion modes are arranged in hierarchy consistent with the order that they are identified and the number of distortions to be identified depends on the required model precision. Based on this, Hamilton's principle is applied to formulate the dynamic governing equations of the beam by constructing its displacement field with the linear superposition of the cross-section mode shapes including distortions. Numerical examples are also presented to validate the new approach and to demonstrate its efficiency in the reproduction of three-dimensional behaviours of thin-walled structures in dynamic analyses.

A New Approach to the Demonstration of Oxidase-Localization Using Tannic Acid Or Catechin

1973 ◽  
Vol 31 ◽  
pp. 698-699
Author(s):  
V. Mizuhira ◽  
Y. Futaesaku
Keyword(s):  
Cross Section ◽  
Tannic Acid ◽  
Elastic Fiber ◽  
The Other ◽  
New Approach ◽  
Tissue Block ◽  
Active Reaction ◽  
The Cross

Previously we reported that tannic acid is a very effective fixative for proteins including polypeptides. Especially, in the cross section of microtubules, thirteen submits in A-tubule and eleven in B-tubule could be observed very clearly. An elastic fiber could be demonstrated very clearly, as an electron opaque, homogeneous fiber. However, tannic acid did not penetrate into the deep portion of the tissue-block. So we tried Catechin. This shows almost the same chemical natures as that of proteins, as tannic acid. Moreover, we thought that catechin should have two active-reaction sites, one is phenol,and the other is catechole. Catechole site should react with osmium, to make Os- black. Phenol-site should react with peroxidase existing perhydroxide.

Energy Distribution in Electron Beams

1972 ◽  
Vol 30 ◽  
pp. 568-569
Author(s):  
Tamotsu Ohno
Keyword(s):  
Electron Beam ◽  
Energy Distribution ◽  
Cross Section ◽  
Integral Curve ◽  
Electron Beams ◽  
Electron Gun ◽  
Angular Divergence ◽  
Apparent Increase ◽  
Integral Width ◽  
The Cross

The energy distribution in an electron; beam from an electron gun provided with a biased Wehnelt cylinder was measured by a retarding potential analyser. All the measurements were carried out with a beam of small angular divergence (<3xl0-4 rad) to eliminate the apparent increase of energy width as pointed out by Ichinokawa.The cross section of the beam from a gun with a tungsten hairpin cathode varies as shown in Fig.1a with the bias voltage Vg. The central part of the beam was analysed. An example of the integral curve as well as the energy spectrum is shown in Fig.2. The integral width of the spectrum ΔEi varies with Vg as shown in Fig.1b The width ΔEi is smaller than the Maxwellian width near the cut-off. As |Vg| is decreased, ΔEi increases beyond the Maxwellian width, reaches a maximum and then decreases. Note that the cross section of the beam enlarges with decreasing |Vg|.

Research in the cross-section of community psychology and global climate change: A call for action

2009 ◽  
Author(s):  
Marci Culley ◽  
Holly Angelique ◽  
Courte Voorhees ◽  
Brian John Bishop ◽  
Peta Louise Dzidic ◽  
...  
Keyword(s):  
Climate Change ◽  
Cross Section ◽  
Global Climate Change ◽  
Community Psychology ◽  
Global Climate ◽  
The Cross

Experimental Studies Of Multilayer Glass Structures On Compression, Compression With Bending And Simple Bending

2019 ◽  
pp. 22-30
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Applied Load ◽  
Experimental Studies ◽  
Strength Properties ◽  
Research Topic ◽  
Normative Values ◽  
Laminated Glass ◽  
The Cross ◽  
Experimental Values

The work of multilayer glass structures for central and eccentric compression and bending are considered. The substantiation of the chosen research topic is made. The description and features of laminated glass for the structures investigated, their characteristics are presented. The analysis of the results obtained when testing for compression, compression with bending, simple bending of models of columns, beams, samples of laminated glass was made. Overview of the types and nature of destruction of the models are presented, diagrams of material operation are constructed, average values of the resistance of the cross-sections of samples are obtained, the table of destructive loads is generated. The need for development of a set of rules and guidelines for the design of glass structures, including laminated glass, for bearing elements, as well as standards for testing, rules for assessing the strength, stiffness, crack resistance and methods for determining the strength of control samples is emphasized. It is established that the strength properties of glass depend on the type of applied load and vary widely, and significantly lower than the corresponding normative values of the strength of heat-strengthened glass. The effect of the connecting polymeric material and manufacturing technology of laminated glass on the strength of the structure is also shown. The experimental values of the elastic modulus are different in different directions of the cross section and in the direction perpendicular to the glass layers are two times less than along the glass layers.

Seasonality in the Cross-Section of Stock Returns

CFA Digest ◽  
2008 ◽  
Vol 38 (3) ◽  
pp. 55-56
Author(s):  
Kathryn Dixon Jost
Keyword(s):  
Stock Returns ◽  
Cross Section ◽  
The Cross
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