scholarly journals Laboratory measurements on gas hydrates and bubbly liquids using active and passive low-frequency acoustic techniques

2011 ◽  
Author(s):  
Chad Greene ◽  
Preston S. Wilson ◽  
Richard B. Coffin
Keyword(s):  
Gas Hydrates ◽  
Low Frequency ◽  
Laboratory Measurements ◽  
Bubbly Liquids ◽  
Acoustic Techniques

A PHASE-PLANE DESCRIPTION OF NONLINEAR TRAVELING WAVES IN BUBBLY LIQUIDS

1999 ◽  
Vol 07 (02) ◽  
pp. 71-82
Author(s):  
A. NADIM ◽  
D. GOLDMAN ◽  
J. J. CARTMELL ◽  
P. E. BARBONE
Keyword(s):  
Equation Of State ◽  
Fixed Points ◽  
Traveling Wave ◽  
Phase Plane ◽  
Volume Fraction ◽  
Low Frequency ◽  
Traveling Wave Solutions ◽  
Bubbly Liquid ◽  
Phase Plane Analysis ◽  
Bubbly Liquids

One-dimensional traveling wave solutions to the fully nonlinear continuity and Euler equations in a bubbly liquid are considered. The elimination of velocity from the two equations leaves a single nonlinear algebraic relation between the pressure and density profiles in the mixture. On assuming the bubbles to have identical size and taking the volume fraction of bubbles in the medium to be small, an equation of state which relates the mixture pressure to the density and its first two material time-derivatives is derived. When this equation of state is linearized and combined with the laws of conservation of mass and momentum, a nonlinear, second-order, ordinary differential equation is obtained for the density as a function of the single traveling wave coordinate. A phase-plane analysis of this equation reveals the existence of two fixed points, one of which is a saddle and the other a node. A single trajectory connects the two fixed points and corresponds to a traveling shock wave solution when the Mach number of the wave, defined as the ratio of traveling wave speed to the low-frequency speed of sound in the bubbly liquid, exceeds unity. The analysis provides a qualitative explanation of the oscillations behind shocks seen in experiments on bubbly liquids.

Low-frequency laboratory measurements of the elastic properties of sandstone flooded with supercritical CO2

2013 ◽  
Vol 53 (2) ◽  
pp. 484
Author(s):  
Vassili Mikhaltsevitch ◽  
Maxim Lebedev ◽  
Boris Gurevich
Keyword(s):  
Supercritical Co2 ◽  
Low Frequency ◽  
Bedding Plane ◽  
Residual Water ◽  
Laboratory Measurements ◽  
Elastic Parameters ◽  
Sandstone Sample ◽  
Confining Pressures ◽  
The Difference ◽  
Set Up

This extended abstract presents the results of the first low-frequency experiments conducted on a sandstone sample (Donnybrook, WA) flooded with supercritical CO2 (scCO2). The experiments investigated the effects of scCO2 injection on the elastic and anelastic properties of the rock. The sandstone sample (porosity—11.4%, permeability—0.28 mD) was cut in the direction orthogonal to a formation-bedding plane and tested in a Hoek's triaxial pressure cell equipped with the means for independent control of pore and confining pressures. The pore and confining pressures were set up at 10 and 31 MPa correspondingly. The low-frequency system and the pump comprising of scCO2 were held at a temperature of 42°C. Supercritical CO2 was injected into the sample preliminary saturated with distilled water. The amount of the residual water in the sample after the scCO2 injection was about 40% of pore volume. The elastic parameters obtained for the sample with scCO2 at frequencies from 0.1–100 Hz are very close to those for the dry sample. Some discrepancy in calculated acoustic velocities are caused by the difference in water and scCO2 densities. The measured extensional attenuation is larger when the sample is saturated with scCO2. The applicability of Gassmann's fluid substitution theory for the interpretation of obtained results was also tested during the experiments.

Performance evaluation of the ISMLR package for predicting the next day's influent wastewater flowrate at Kirie WRP

2019 ◽  
Vol 80 (4) ◽  
pp. 695-706 ◽  
Author(s):  
Jun-Jie Zhu ◽  
Paul R. Anderson
Keyword(s):  
Low Frequency ◽  
Soft Sensor ◽  
Wastewater Management ◽  
Laboratory Measurements ◽  
Data Retention ◽  
Intelligent Monitoring ◽  
Know How ◽  
Sensor Applications ◽  
Frequency Monitoring ◽  
Available Information

Abstract Soft-sensor applications for wastewater management can provide valuable information for intelligent monitoring and process control above and beyond what is available from conventional hard sensors and laboratory measurements. To realize these benefits, it is important to know how to manage gaps in the data time series, which could result from the failure of hard sensors, errors in laboratory measurements, or low-frequency monitoring schedules. A robust soft-sensor system needs to include a plan to address missing data and efficiently select variable(s) to make the most use of the available information. In this study, we developed and applied an enhanced iterated stepwise multiple linear regression (ISMLR) method through a MATLAB-based package to predict the next day's influent flowrate at the Kirie water reclamation plant (WRP). The method increased the data retention from 77% to 93% and achieved an adjusted R2 up to 0.83 by integrating with a typical artificial neural network.

Magnetic susceptibility mapping of the Sudbury area, Ontario, Canada: evaluating pollution distributions decades later

2016 ◽  
Vol 53 (5) ◽  
pp. 466-484 ◽  
Author(s):  
A. Yurtseven-Sandker ◽  
M.T. Cioppa
Keyword(s):  
Magnetic Susceptibility ◽  
Iron Sulfide ◽  
Mine Waste ◽  
Low Frequency ◽  
Temporal Variations ◽  
Health Concern ◽  
Laboratory Measurements ◽  
Magnetic Minerals ◽  
Mining Sites

This study evaluates the use of magnetic susceptibility and magnetic parameter measurements in assessing spatial and temporal variations of pollutants that emanated from mining industries in and around Sudbury, Ontario, Canada. For this purpose, in situ magnetic susceptibility (κin situ) was measured at 106 sites on a grid of 10 km × 10 km and 5 km × 5 km. The κin situ values ranged from 2 × 10−5 to 149 × 10−5 SI, and the highest κin situ values were observed near the active (Copper Cliff) and inactive (Coniston) mining sites. The lowest κin situ values were measured at increased distances from possible pollution sources; therefore, mapping of in situ magnetic susceptibility values is a proxy to polluted areas in and around Sudbury. To evaluate potential anthropogenic and (or) lithogenic input to κin situ, low-frequency mass specific magnetic susceptibility (χlf) variations with depth were classified into four different types of profiles. For further investigation of magnetic minerals in the samples, laboratory measurements of magnetic susceptibility, frequency dependence of magnetic susceptibility, hysteresis properties, thermosusceptibility curves, anhysteretic and isothermal magnetizations, and scanning electron microscopy – energy-dispersive X-ray spectroscopy (SEM–EDS) were also conducted on the soil samples. Laboratory measurements indicated that ferrimagnetic minerals (e.g., magnetite) of variable grain size were the dominant magnetic minerals, with the exception of one site that contained an iron sulfide (greigite) phase near a mine waste site. Magnetic spherules observed in SEM micrographs are of variable sizes (6–60 μm), suggesting that suspended particulate matter (PM10) is present, and may be a health concern. At some sites, EDS analysis showed that heavy metals (Co, Al, and Ni), which threaten human health, are also present in the study area.

Wave propagation in bubbly liquids at finite volume fraction

1985 ◽  
Vol 160 ◽  
pp. 1-14 ◽  
Author(s):  
Russel E. Caflisch ◽  
Michael J. Miksis ◽  
George C. Papanicolaou ◽  
Lu Ting
Keyword(s):  
Wave Propagation ◽  
Finite Volume ◽  
Small Volume ◽  
Volume Fraction ◽  
Low Frequency ◽  
Multiple Scale ◽  
Bubbly Liquid ◽  
Bubbly Liquids ◽  
Frequency Regime ◽  
Small Volume Fraction

We derive effective equations for wave propagation in a bubbly liquid in a linearized low-frequency regime by a multiple-scale method. The effective equations are valid for finite volume fraction. For periodic bubble configurations, effective equations uniformly valid for small volume fraction are obtained. We compare the results to the ones obtained in a previous paper (Caflisch et al. 1985) for a nonlinear theory at small volume fraction.

Laboratory measurements of low‐frequency acoustic scattering from a buried canonical target

2000 ◽  
Vol 107 (5) ◽  
pp. 2921-2921
Author(s):  
Harry J. Simpson ◽  
Brian H. Houston ◽  
Carl K. Frederickson
Keyword(s):  
Acoustic Scattering ◽  
Low Frequency ◽  
Laboratory Measurements
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