Sonic Frequencies Research Articles

Sensate vibratory prosthesis

First Page

Sonic method for facilitating the fracturing of earthen formations in well bore holes

A pressurized liquid column is fed down the tubing string of a well and out of the well to the earthen formation at the bottom of the string. Mounted within the tubing string is an elastic rod string and the tubing plus the rod may comprise an elastic column. A vibration generator which may comprise an orbiting mass oscillator is mounted on the top of the rod string or both rod and tubing, the oscillator being operated at a sonic frequency which will effect resonant standing wave vibration of the rod string. A plurality of sonic impeller elements are fixedly mounted on the rod string at spaced intervals therealong, the spacing between such impeller elements being les than 1/10th of the wave length of the standing waves. The impeller elements are designed and oriented so as to effect downward pumping action of the liquid column in response to the sonic energy. This pumping action effects high pressure pulses against the earthen formation which causes fracturing thereof so as to create fissures therein; thereby enhancing the yield of the well.

Nondestructive Depth Profiling of a Diffuse Interface

AbstractA numerical solution of the one-dimensional wave equation is used to find the characteristics of wave propagation in a non-homogeneous medium. The solution is used to determine the magnitude and phase of the reflection coefficient at a diffuse interface. The result is found to be strongly dependent on sonic frequency. Comparison is made between theoretical calculations and measurements of the reflection coefficient at a copper-to-nickel diffusion bond.

Vp/Vs in unconsolidated oil sands: Shear from Stoneley

The SDT-A sonic tool was tested in a borehole in the Orinoco heavy oil belt, eastern Venezuela. The sonically slow reservoir consists of unconsolidated quartz sand interbedded with shale. Full‐waveform analysis yields both compressional and shear slownesses. We calculated the shear‐wave slowness from the Stoneley slowness; compressional and Stoneley slownesses were determined using modified semblance techniques. The compressional velocity is relatively fast in the heavy oil pay zone compared to the remainder of the well. Heavy oil (8 API) possesses a finite rigidity at sonic frequencies, and the rigidity of the hydrocarbon adds to the stiffness of the poorly consolidated sand. The sand would not otherwise yield such a high velocity. Compressional and shear velocities of samples from eight whole cores were measured in the laboratory, and the core velocities were found to be consistent with the logs. Especially encouraging is the agreement of the laboratory shear with the shear log derived from Stoneley. The ratio of the compressional‐to‐shear velocities, [Formula: see text], is sensitive to fluid saturation and rock fabric. The oil sands have a [Formula: see text] of less than 2.5. The shales in the well have a [Formula: see text] of greater than 2.5. We found that water‐saturated formations are governed by Biot’s theory, while oil sands are better described by scattering theory. A third arrival has been identified as a leaky compressional mode trapped in the borehole. The velocity of the mode is dominated by the slowness of the borehole mud.

The role of prey-generated sounds, vision, and echolocation in prey localization by the African batCardioderma cor (Megadermatidae)

Cardioderma cor responded with head movements and flight toward speakers broadcasting calls of frogs and crickets which contained only sonic frequencies. Unlike the frog-eating bat,Trachops cirrhosus, they did not make contact with the speakers. Prey movements that generated sonic and ultrasonic sounds were both sufficient and necessary for the bats to localize and capture prey. Prey dragged across a glass sheet with a thin layer of water did not generate sounds and bats did not attempt to capture these prey, even with the availability of visual and echolocation cues. There was no evidence for the use of visual cues while hunting; bats did not localize prey more readily in light than darkness. Prey were presented such that their movements initially generated sounds, but then the prey moved onto the water layer of the glass sheet and sounds were eliminated. The bats emitted echolocation signals while hunting in this situation; however, the information from these signals was not utilized. The bats landed at the site that prey last made sound. These results demonstrate the importance of passive hearing for prey localization in this bat, and further suggest that when preygenerated sounds and echolocation signals offer conflicting information the bat's behavior is guided by the former.

Nature of fatigue failure of glass at sonic and ultrasonic loading frequencies

Nature of fatigue failure of glass at sonic and ultrasonic loading frequencies

Murine vocalizations: Experimental validation of a novel detector

A new device to detect vocalizations by mice or rats is described. Of modest cost and incorporating integrated circuits and controls that permit rapid setting of center frequency and sensitivity, the device is based on phase-locked tone decoding and can operate at sonic or ultrasonic frequencies. Circuit operation and schematics are provided, as are data from two studies of mice in which reliable discrimination of distress and submission calls from background noise was demonstrated.

‘Strength of materials and structural components at sonic and ultrasonic loading frequencies’ symposium

‘Strength of materials and structural components at sonic and ultrasonic loading frequencies’ symposium

Transgastric ultrasonography of the pancreas

This is a report of initial experience gained with the transgastric diagnostic examination of the pancreas in a total of 80 patients. The examinations were carried out with two different instruments. One of the two fiberscopes carries on its tip a mechanical sector scanner, the scan plane of which is angulated through 90° vis-a-vis the longitudinal axis of the instrument. The other ultrasonic endoscope is provided with an ultrasonic linear array assembly arranged along the longitudinal axis of the instrument. The sonic frequency is 7 and 7.5 MHz, respectively, so that the quality of resolution obtained is equal to that of a “small parts” scanner. Intubation of the stomach is readily possible with either instrument. In contrast, owing to the relatively long inflexible tip of the instrument, intubation of the duodenum proved impossible in about one quarter of the patients, in particular when the duodenum was deformed by scar tissue. The topographic-anatomic orientation proved difficult, in particular since the scan planes are strictly determined by the position of the endoscope. A systematic examination of the pancreas in two planes is, as a result, virtually impossible. All in all, therefore, the technique must be considered merely as a supplementary procedure to external diagnostic ultrasonography. Thanks to its superior resolution, and the avoidance of such obstacles as “bowel gas”, however, it is capable, as a supplementary examination, of providing additional diagnostic information about lesions of the pancreas.

The construction and assessment of lenses for local treatment of malignant tumours by ultrasound

A simple method to build ultrasound lenses from araldite has been developed. The focussing properties of these lenses as a function of sonic frequency and lens diameter were studied using a computer model. The optimum frequency and diameter of these lenses were found to be around 1 MHz and between 40 and 60 mm respectively, for deep tissue heating. The stability of the power output as well as the temperature distributions produced in vitro and in vivo have also been studied. It appears to be possible to produce larger temperature elevations near the acoustical focus than near the skin surface in vivo. Therefore the lenses seem to be suitable for local cancer treatment.

Behavioral responses of the frog-eating bat,Trachops cirrhosus, to sonic frequencies

The frog-eating bat,Trachops cirrhosus (Phyllostomatidae), locates frogs by using the frogs' vocalizations and shows a behavioral response to constant frequencies in the sonic range. The minimum intensity needed to elicit a behavioral response to a constant frequency (i.e. threshold intensity) increased as the frequency decreased from 15 kHz to 5 kHz. This is consistent with audiograms of other bats that have been tested in the sonic range. However, the threshold ofT. cirrhosus decreases with frequencies below 5 kHz, which is unusual among bats so far tested in this frequency range. This decreased threshold coincides with the frequencies which characterize frog calls that the bats use to locate their prey.

Shear wave velocity measurements in marine sediments

Pulsed ultrasonic techniques for the measurement of sound speed are reliable and well documented. Extension of these techniques to the measurement of shear wave velocities in marine sediments, generally was unsuccessful. Recently developed shear wave transducers, based upon piezoelectric benders operated at sonic frequencies, provide significantly improved transducer-sample mechanical coupling. This improved coupling allows the application of pulsed techniques to the measurement of shear wave velocities in marine sediments, and the rapid determination of sediment dynamic elastic properties. Two types of bender-based shear wave transducer and preliminary data are described: 1) a probe configuration for box core samples, and 2) a modification to the Hamilton Frame Velocimeter for cut samples.

Ultrasonic characteristics of a rock mass

A programme aimed at the in-situ assessment of rock properties and rock condition has been undertaken at the Julius Kruttschnitt Mineral Research Centre of the University of Queensland. The project aims to quantify rock mass parameters and to use them in a model of blasting to predict and control fragmentation. A technique for characterization of a rock mass utilizing acoustic data obtained from test or production boreholes was investigated as part of the programme. The system is a cross-hole acoustic system which uses wave propagation velocities and the attenuation parameter, Q (as estimated from a measurement of the change in pulse shape during propagation) to asses the rock mass condition. This system is a modification of the ultrasonic stress monitoring device (USMD) developed by Gladwin [5] in which a magnetostrictive transducer, mechanically clamped in an NX borehole is used to produced ultrasonic pulses of approximately 37.5 kHz. Pulse transmission times to detectors clamped at measured depths are used to produce a velocity profile for distances of up to 15 m from the source hole. The viability of the technique and the required instrument specifications, have been studied in a series of field experiments, which indicate good agreement between structural core log data and pulse rise time. Characterization of the state of fracture of a rock mass is being carried out at several sites with markedly different geological environments. These sites include a high grade open cut hematite mine, an open cut coal mine, an underground dolomitic copper ore body, and an underground lead-zinc ore body. The ultrasonic technique is being supplemented by studies in the sonic frequency range using small explosive charges as a acoustic sources. A comparison between the two sets of data will be made for both velocity and Q measurements for the preliminary field experimentation.

Elastically vibratory longitudinal jacketed drill

A drill bit is connected to the bottom end of a longitudinally elastic drill stem which is contained within a jacket. An orbiting mass oscillator is coupled to the drill stem, this oscillator generating vibrational energy at a sonic frequency. The rotation axis of the oscillator is parallel to the drill stem, the drill stem being driven elastically, preferably at a frequency such as to set up standing waves therein, whereby circumferentially successive lengthwise oriented regions around the periphery of the column cyclically elongate and contract longitudinally in rotary progression. This longidudinal vibratory energy is transferred to the drill bit causing nutation thereof such that successive portions of the bit drive into the work material in a progression of longitudinal impulses as the stem undergoes circumferentially successive longitudinal cyclic motion in response to the vibratory energy applied thereto. This motion is limited by a jacket which surrounds the stem, thus effectively limiting the cyclic stress of this stem and isolating the vibrations thereof from the supporting structure of the assembly.

Ultrasonic attenuation in normal and superconducting indium

Abstract : The dependence of ultrasonic attenuation on temperature, sonic frequency, propagation direction, and superconducting state has been measured in indium single crystals using low-amplitude longitudinal waves. These measurements and the experimental apparatus with which they have been obtained are described. These data indicate that, in addition to the usual electronic attenuation described quantitatively by the BCS theory of superconductivity (Bardeen et al., Phys. Rev. 108, 1175), there is an additional source of attenuation. This secondary attenuation is generally attributed to the interaction of sound waves and crystal dislocations within the specimen, a process which has been described most thoroughly by Granato and Lucke (J. Appl. Phys. 27, 583). A comparison of the measured dislocation attenuations with those predicted by the theory of Granato and Lucke is given. This theory is shown to be inapplicable to the situation of this experiment, i.e., to indium at low temperatures. Earlier works in which similar data appear to substantiate the Granato and Lucke theory of dislocation attenuation are shown to be insufficient tests of that theory. (Author)

Measuring system for complex shear modulus of liquids using torsionally vibrating quartz crystals

In rheology, torsionally vibrating quartz crystals are in use to determine dynamic shear moduli of liquids in the sonic and ultrasonic frequency range. A computer controlled measuring system using such crystals is described. The main advantages of this system are high measuring speed with respect to the manual AC bridge method and on-line data reduction. As an illustration measurements of a solution of polystyrene in toluene in the 10-100 kHz range are presented.

An acoustic study of pulsation characteristics of fires

The pulsation characteristic of fires was examined using acoustic parameters at very low sonic and subsonic frequencies up to 2 Hz. The existences of a characteristic frequency related to the diameter of the seat of the fire was demonstrated. The signal was found to decay rapidly with distance, suggesting displacement of the medium rather than vibrations in the medium. The use of this type of effect in fire detection is also discussed.

Sonic fishing lure

First Page

Attenuation of seismic waves in dry and saturated rocks: II. Mechanisms

Theoretical models based on several hypothesized attenuation mechanisms are discussed in relation to published data on the effects of pressure and fluid saturation on attenuation. These mechanisms include friction, fluid flow, viscous relaxation, and scattering. The application of these models to the ultrasonic data of Toksöz et al (1979, this issue) indicates that friction on thin cracks and grain boundaries is the dominant attenuation mechanism for consolidated rocks under most conditions in the earth’s upper crust. Increasing pressure decreases the number of cracks contributing to attenuation by friction, thus decreasing the attenuation. Water wetting of cracks and pores reduces the friction coefficient, facilitating sliding and thus increasing the attenuation. In saturated rocks, fluid flow plays a secondary role relative to friction. At ultrasonic frequencies in porous and permeable rocks, however, Biot‐type flow may be important at moderately high pressures. “Squirting” type flow of pore fluids from cracks and thin pores to larger pores may be a viable mechanism for some rocks at lower frequencies. The extrapolation of ultrasonic data to seismic or sonic frequencies by theoretical models involves some assumptions, verification of which requires data at lower frequencies.

Interconnected fibre masses precipitated from solutions of polymers

IN studies to increase the mechanical strength of polymeric encapsulants for high voltage electronic devices we have formed fibre masses of unusual structure from isotactic polypropylene. The method for producing these three-dimensionally interconnected fibrous structures is described here and involves agitation of a solution of the polymer at sonic frequencies with simultaneous cooling. This process has since been observed for polyethylene and polybutene-1. Furthermore, the process has been extended to other polymers, both crystalline and non-crystalline, through a process we call ‘seeding’. Uniform reinforcement of encapsulating resins through the addition of high strength, short fibres, is not practical because of the complex shapes and numerous small interstices of the devices to be encapsulated. We therefore set out in 1973 to form fibres in situ by precipitation from low viscosity solutions which would readily impregnate a device of complex geometry. As a secondary objective, we hoped to polymerise the solvent to form a matrix around the fibres thereby producing a self-reinforced composite.