scholarly journals Analysis of Local Seismic Events near a Large-N Array for Moho Reflections

2020 ◽  
Vol 92 (1) ◽  
pp. 408-420
Author(s):  
Qicheng Zeng ◽  
Robert L. Nowack
Keyword(s):  
Poisson’S Ratio ◽  
Velocity Model ◽  
Poisson's Ratio ◽  
Moho Depth ◽  
Seismic Events ◽  
Wide Angle ◽  
Large N ◽  
Static Corrections ◽  
The Difference ◽  
The Individual

Abstract Local seismic events recorded by the large-N Incorporated Research Institutions for Seismology Community Wavefield Experiment in Oklahoma are used to estimate Moho reflections near the array. For events within 50 km of the center of the array, normal moveout corrections and receiver stacking are applied to identify the PmP and SmS Moho reflections on the vertical and transverse components. Corrections for the reported focal depths are applied to a uniform event depth. To stack signals from multiple events, further static corrections of the envelopes of the Moho reflected arrivals from the individual event stacks are applied. The multiple-event stacks are then used to estimate the pre-critical PmP and SmS arrivals, and an average Poisson’s ratio of 1.77±0.02 was found for the crust near the array. Using a modified Oklahoma Geological Survey (OGS) velocity model with this Poisson’s ratio, the time-to-depth converted PmP and SmS arrivals resulted in a Moho depth of 41±0.6  km. The modeling of wide-angle Moho reflections for selected events at epicenter-to-station distances of 90–135 km provides additional constraints, and assuming the modified OGS model, a Moho depth of 40±1  km was inferred. The difference between the pre-critical and wide-angle Moho estimates could result from some lateral variability between the array and the wide-angle events. However, both estimates are slightly shallower than the original OGS model Moho depth of 42 km, and this could also result from a somewhat faster lower crust. This study shows that local seismic events, including induced events, can be utilized to estimate properties and structure of the crust, which, in turn, can be used to better understand the tectonics of a given region. The recording of local seismicity on large-N arrays provides increased lateral phase coherence for the better identification of precritical and wide-angle reflected arrivals.

The Effect of Design Changes on Sound Transmission through a Building

1996 ◽  
Vol 3 (3) ◽  
pp. 145-185
Author(s):  
Robert J.M. Craik
Keyword(s):  
Young’S Modulus ◽  
Poisson’S Ratio ◽  
Young's Modulus ◽  
Sound Transmission ◽  
Poisson's Ratio ◽  
Analysis Model ◽  
Room Size ◽  
Design Changes ◽  
Small Change ◽  
The Individual

A statistical energy analysis model of a building was used to assess the effect of design changes on sound transmission. Systematic changes were made to the material properties (density, Young's modulus, Poisson's ratio and internal loss factor) and to the dimensions (thickness and room size). These changes resulted in a redistribution of the energy throughout the building causing the noise level to go up in some rooms and to go down in others. For each case examined it was found that the effect of several changes could be estimated from the sum of the individual changes. Thus a change of 20% in the density resulted in approximately double the change in DnTw that was obtained from a 10% change in density. The same additive effect was also found to apply if more than one variable was changed at the same time. Thus the change in DnTw resulting from a small change in Young's modulus for the floors and a small change in the density of the walls can be estimated from the sum of the two individual effects. Changes to the thickness and density of the walls and floors have the greatest effect on sound transmission whilst changes to Young's modulus and Poisson's ratio have a much smaller effect. Damping can also have a significant effect on transmission particularly far from the source.

scholarly journals Structure Dependence of Poisson’s Ratio in Cesium Silicate and Borate Glasses

Materials ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 2837
Author(s):  
Martin B. Østergaard ◽  
Mikkel S. Bødker ◽  
Morten M. Smedskjaer
Keyword(s):  
Poisson’S Ratio ◽  
Network Connectivity ◽  
Silicate Glasses ◽  
Poisson's Ratio ◽  
Borate Glasses ◽  
Oxide Glasses ◽  
Topological Constraint ◽  
Binary Glass ◽  
The Difference ◽  
Positive Correlations

In glass materials, Poisson’s ratio (ν) has been proposed to be correlated with a variety of features, including atomic packing density (Cg), liquid fragility (m), and network connectivity. To further investigate these correlations in oxide glasses, here, we study cesium borate and cesium silicate glasses with varying modifier/former ratio given the difference in network former coordination and because cesium results in relatively high ν compared to the smaller alkali modifiers. Within the binary glass series, we find positive correlations between ν on one hand and m and Cg on the other hand. The network former is found to greatly influence the correlation between ν and the number of bridging oxygens (nBO), with a negative correlation for silicate glasses and positive correlation for borate glasses. An analysis based on topological constraint theory shows that this difference cannot be explained by the effect of superstructural units on the network connectivity in lithium borate glasses. Considering a wider range of oxide glasses from the literature, we find that ν generally decreases with increasing network connectivity, but with notable exceptions for heavy alkali borate glasses and calcium alumino tectosilicate glasses.

scholarly journals Prediction of Pore Size Characteristics of Needle-Punched Nonwoven Geotextiles Subjected to Uniaxial Tensile Strains

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Lin Tang ◽  
Qiang Tang ◽  
Aolai Zhong ◽  
Hanjie Li
Keyword(s):  
Pore Size ◽  
Poisson’S Ratio ◽  
Poisson's Ratio ◽  
Uniaxial Tensile ◽  
Modified Model ◽  
Pore Sizes ◽  
Pore Size Distributions ◽  
Out Of Plane ◽  
Tensile Strains ◽  
The Difference

A modified theoretical model has been proposed to predict the pore size characteristics of nonwoven geotextiles under certain uniaxial tensile strains, considering the difference between the out-of-plane Poisson’s ratio and the in-plane Poisson’s ratio of geotextiles. The pore size distributions (PSDs) and O95 subjected to different levels of uniaxial tensile strains in two needle-punched nonwoven geotextiles have been investigated by the dry sieving test. The variation of the fibre orientation with tensile strains and the corresponding effect on pore sizes has been evaluated by image analysis. The out-of-plane Poisson’s ratio and the in-plane Poisson’s ratio of geotextiles have been examined. A comparison has been made between the predictions of the original and the modified models. It is shown that the modified model can more accurately predict the decreasing rate of the PSDs, O95, and O98 than the original one. The corrected theoretical O95 and O98 under certain strains can provide a reference for the filtration design under engineering strains. The fibres reorientating to the loading direction result in the increase of the directional parameter with increasing tensile strains, which leads to the decrease of pore sizes. The theoretical PSDs are sensitive to the variation of directional parameter.

Analysis of Spherical Contact Models for Differential Hardness as a Function of Poisson's Ratio

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
Giuseppe Pintaude
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Yield Stress ◽  
Poisson’S Ratio ◽  
Large Deformations ◽  
Poisson's Ratio ◽  
Spherical Contact ◽  
Indentation Process ◽  
Contact Models ◽  
The Difference

A differential hardness is needed for a spherical indenter to avoid large deformations of it during an indentation process. Tabor proposes a criterion for this, where the ball hardness should be at least 2.5 times harder than the specimen. Later, five models expand the Tabor proposal, such that the critical interference corresponding to the inception of plastic deformation depends on the Poisson's ratio. This paper discusses the difference among these models, showing that they can be divided in two groups only. In addition, their similarity depending on the specific mechanical properties of tested material was used to make the conversion between yield stress and hardness.

An Application of the Interferometer Strain Gage in Photoelasticity

1935 ◽  
Vol 2 (3) ◽  
pp. A99-A102
Author(s):  
R. W. Vose
Keyword(s):  
Strain Gage ◽  
Poisson’S Ratio ◽  
Poisson's Ratio ◽  
Massachusetts Institute ◽  
Massachusetts Institute Of Technology ◽  
Lateral Deformation ◽  
Principal Stresses ◽  
Photoelastic Analysis ◽  
The Difference ◽  
Institute Of Technology

Abstract This paper was written at the suggestion of Mr. Mieth Maeser, in response to numerous inquiries concerning the methods of photoelastic analysis in use at the Massachusetts Institute of Technology. By the use of any of the usual photoelastic methods the difference of the principal stresses and their direction at any point in a suitable loaded specimen are determined, and through a knowledge of Poisson’s ratio their sum is obtained (and a solution made possible) by a measurement of the lateral deformation of the specimen by means of an interferometer strain gage. This instrument, together with its accessories and their use, is illustrated and described in the paper. Examples of the problems solved by the use of the instrument show its accuracy and the consistency of the results obtained by the method.

Velocity-porosity relationships, 1: Accurate velocity model for clean consolidated sandstones, GEOPHYSICS, 68, 1822–1834.

Geophysics ◽  
2006 ◽  
Vol 71 (2) ◽  
pp. Y3-Y3
Author(s):  
Mark A. Knackstedt ◽  
Christoph H. Arns ◽  
W. Val Pinczewski
Keyword(s):  
Poisson’S Ratio ◽  
Empirical Equation ◽  
Velocity Model ◽  
Poisson's Ratio ◽  
Porous Rock

The empirical equation of Arns et al., 2002a, is reproduced incorrectly in this paper as equation 22. The correct nonlinear empirical equation for the Poisson's ratio of a dry porous rock should read

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