scholarly journals Study of agricultural material frequency response in order to ensure safety of technologies using super high frequencies

2020 ◽  
Author(s):  
Elena Logacheva ◽  
Valery Zhdanov ◽  
Alexander Ivashina ◽  
Viktor Yarosh
Keyword(s):  
Frequency Response ◽  
High Frequencies ◽  
Agricultural Material

scholarly journals Diffuse-Field Equalisation of Binaural Ambisonic Rendering

2018 ◽  
Vol 8 (10) ◽  
pp. 1956 ◽  
Author(s):  
Thomas McKenzie ◽  
Damian Murphy ◽  
Gavin Kearney
Keyword(s):  
Virtual Reality ◽  
Frequency Response ◽  
Sound Source ◽  
High Frequency ◽  
Sagittal Plane ◽  
Impulse Responses ◽  
Spectral Difference ◽  
High Frequencies ◽  
Listening Tests ◽  
Frequency Reproduction

Ambisonics has enjoyed a recent resurgence in popularity due to virtual reality applications. Low order Ambisonic reproduction is inherently inaccurate at high frequencies, which causes poor timbre and height localisation. Diffuse-Field Equalisation (DFE), the theory of removing direction-independent frequency response, is applied to binaural (over headphones) Ambisonic rendering to address high-frequency reproduction. DFE of Ambisonics is evaluated by comparing binaural Ambisonic rendering to direct convolution via head-related impulse responses (HRIRs) in three ways: spectral difference, predicted sagittal plane localisation and perceptual listening tests on timbre. Results show DFE successfully improves frequency reproduction of binaural Ambisonic rendering for the majority of sound source locations, as well as the limitations of the technique, and set the basis for further research in the field.

Externally Pressurized Bearings—II: Vibration Attenuators

1968 ◽  
Vol 90 (3) ◽  
pp. 614-617 ◽  
Author(s):  
D. F. Wilcock ◽  
W. E BeVier
Keyword(s):  
Frequency Response ◽  
Closed Loop ◽  
Magnetic Hysteresis ◽  
Rolling Element Bearings ◽  
High Frequencies ◽  
Gear Teeth ◽  
Hydrostatic Bearing ◽  
Performance Factors ◽  
Rolling Element ◽  
Turbine Blading

Rolling element bearings are vibration generators, and in addition are stiff, so that they transmit rotor generated noise as well to the machine frame and casing. Self-acting (hydrodynamic) bearings are also very rigid, so that they are excellent transmitters of rotor generated vibration, e.g., front gear teeth, turbine blading, or magnetic hysteresis. A typical rotor weighing 1000 lb may be supported on bearings having a stiffness of 3 × 106 lb/in., and hence will be a good vibration transmitter up to a frequency of 172 cps. Hydrostatic bearings afford an opportunity to control the bearing frequency response so that attenuation of middle and high frequencies can be secured. Analysis of the hydrostatic bearing as a closed-loop servomechanism reveals methods of designing them for attenuation without serious consequences in other performance factors. They may be used as the primary bearing, or as separate isolator bearings in conjunction with rolling element or self-acting bearings. Some examples of possible applications are discussed.

Interaural Intensity and Time Differences in Anechoic and Reverberant Rooms

1967 ◽  
Vol 10 (2) ◽  
pp. 177-185 ◽  
Author(s):  
Donald Dirks ◽  
John P. Moncur
Keyword(s):  
Frequency Response ◽  
Sound Pressure ◽  
Anechoic Chamber ◽  
Intensity Level ◽  
Average Response ◽  
Response Curves ◽  
Interaural Time Differences ◽  
High Frequencies ◽  
Intensity Changes ◽  
Free Environment

The purpose of this investigation was to describe the physical characteristics of an artificial head and to determine the interaural time and intensity changes which occurred at selected azimuths. Measurements were conducted in a reflection free environment and in controlled reverberation conditions. The frequency response of the head microphones simulated the average response curves at the human auditory canal. In the anechoic chamber, the sound pressure at the ear nearest the speaker remained constant as the head moved from 0° azimuth to 45° and 90°. A reduction in intensity was observed in the far ear at azimuths of 45° and 90°. The decrease in sound pressure was observed in the middle and high frequencies. A “build-up” in the intensity level was found during the reverberant conditions. In the anechoic chamber, interaural time differences ranged from 0.42 to 0.56 msec at 45° azimuth and from 0.76 to 0.81 msec at 90° azimuth.

Representation of frequency in the primary auditory field of the barn owl forebrain

1996 ◽  
Vol 76 (6) ◽  
pp. 3682-3692 ◽  
Author(s):  
Y. E. Cohen ◽  
E. I. Knudsen
Keyword(s):  
Frequency Response ◽  
Interindividual Variability ◽  
Frequency Tuning ◽  
Barn Owl ◽  
Auditory Information ◽  
Low Frequencies ◽  
High Frequencies ◽  
Frequency Representation ◽  
Response Profiles ◽  
Auditory Field

1. The primary auditory field (PAF) constitutes the first telencephalic stage of auditory information processing in the classical auditory pathway. In this study we investigated the frequency representation in the PAF of the barn owl, a species with a broad frequency range of hearing and a highly advanced auditory system. 2. Single- and multiunit sites were recorded extracellularly in ketamine-anesthetized owls. The frequency response properties of PAF sites were assessed with the use of digitally synthesized dichotic stimuli. PAF sites (n = 442) either were unresponsive to tonal stimulation (but responsive to noise stimuli), were tuned for frequency, or had multipeaked frequency response profiles. Tuned sites responded best to frequencies between 0.2 and 8.8 kHz, a range that encompasses nearly the entire hearing range of the barn owl. Most sites responding best to frequencies < 4 kHz had relatively broad frequency tuning, whereas sites responding best to higher frequencies had either broad or narrow frequency tuning. Sites with multipeaked frequency response profiles typically had two response peaks. The first peak was usually between 1 and 3 kHz and the second was usually between 5 and 8 kHz; there was no systematic relationship between the two peak frequencies. 3. In dorsoventral electrode penetrations that contained sites with tuned and/or multipeaked response profiles, a “common frequency” was identified that elicited a maximal response from all of the sites in the penetration. 4. The PAF contains a single tonotopic field. Units tuned to low frequencies are located caudomedially, whereas units tuned to high frequencies are located rostrolaterally. Compared with the frequency representation along the basilar papilla and in other auditory structures, the PAF overrepresents low frequencies (< 4 kHz) that are important for barn owl vocalizations. Conversely, high frequencies (> or = 4 kHz), which are necessary for precise sound localization, are underrepresented relative to these more peripheral auditory structures. 5. There was considerable interindividual variability both in the relative magnification of different frequency ranges and in the orientation of the tonotopic map in the brain. 6. These results suggest that the barn owl PAF, like the mammalian primary auditory cortex, is a general processor of auditory information that is involved in the analysis of both the meaning (such as species-specific vocalizations) and the location of auditory stimuli. In addition, the high degree of interindividual variability in the representation of frequency information suggests that the barn owl PAF, like the mammalian auditory cortex, is subject to modification by sensory experience.

scholarly journals The relative frequency response derived from individually separated targets of northeast Arctic cod (Gadus morhua), saithe (Pollachius virens), and Norway pout (Trisopterus esmarkii)

2009 ◽  
Vol 66 (6) ◽  
pp. 1149-1154 ◽  
Author(s):  
Geir Pedersen ◽  
Rolf J. Korneliussen
Keyword(s):  
Frequency Response ◽  
Relative Frequency ◽  
Gadus Morhua ◽  
Target Strength ◽  
Reference Frequency ◽  
Acoustic Measurements ◽  
Arctic Cod ◽  
High Frequencies ◽  
Specific Frequency

Abstract Pedersen, G., and Korneliussen, R. J. 2009. The relative frequency response derived from individually separated targets of northeast Arctic cod (Gadus morhua), saithe (Pollachius virens), and Norway pout (Trisopterus esmarkii). – ICES Journal of Marine Science, 66: 1149–1154. The concept of relative frequency response r(f) of fish is an important feature used to characterize acoustic targets. It is defined as the volume-backscattering coefficient at a specific frequency f relative to that of a reference frequency. When based on volume backscattering, r(f) reliably distinguishes several acoustic categories if the insonified volumes are reasonably comparable between the frequencies, and that enough samples and targets are measured to constrain stochastic variations in the data within acceptable limits. Therefore, r(f) distinguishes different fish species with swimbladders poorly if they appear as single targets. Using target-strength (TS) data, the acoustic measurements are more spatially comparable, and averaging the TS over an echotrace of a single fish improves the ability to distinguish between different species. Frequency response was estimated using TS data from in situ measurements, collected using Simrad EK60 echosounders with split-beam transducers transmitting simultaneously at 18, 38, 70, 120, and 200 kHz. Selected series with nearly pure catches of northeast Arctic cod (Gadus morhua), saithe (Pollachius virens), and Norway pout (Trisopterus esmarkii) were analysed using a target-tracking algorithm. The frequency response of northeast Arctic cod and saithe did not differ significantly, but at high frequencies, the response of both northeast Arctic cod and saithe differed from that of Norway pout. However, in the latter case, northeast Arctic cod and saithe could be separated, because of their different TS magnitudes.

An electrodynamic shaker with an integral force gauge for high-frequency measurements on lightweight structures

2000 ◽  
Vol 214 (10) ◽  
pp. 1285-1297 ◽  
Author(s):  
R M Grice ◽  
R J Pinnington
Keyword(s):  
Frequency Response ◽  
Piezoelectric Material ◽  
Response Function ◽  
High Frequency ◽  
Frequency Response Function ◽  
Dynamic Behaviour ◽  
High Frequencies ◽  
Lightweight Structures ◽  
Electrodynamic Shaker ◽  
Design Construction

The design, construction and calibration of a purpose-built electrodynamic shaker for making frequency response function measurements on lightweight structures at high frequencies (i.e. many kHz) are described. The shaker uses a conventional wire-wound coil onto which is assembled a force gauge. The force gauge is constructed using little more than just a miniature piece of piezoelectric material. The dimensions of the components used to manufacture the shaker are determined by comparing their estimated dynamic behaviour with the estimated mobility of a lightweight perspex test structure. Although such an electrodynamic shaker is not entirely novel, it demonstrates how careful use of basic materials can produce a device that overcomes some limitations of commercial devices at very little cost.

scholarly journals Frequency response of ice streams

2012 ◽  
Vol 468 (2147) ◽  
pp. 3285-3310 ◽  
Author(s):  
C. Rosie Williams ◽  
Richard C. A. Hindmarsh ◽  
Robert J. Arthern
Keyword(s):  
Frequency Response ◽  
Dynamical Response ◽  
Ice Shelf ◽  
Ice Streams ◽  
Ice Dynamics ◽  
Low Frequencies ◽  
High Frequencies ◽  
Grounding Line ◽  
Propagation Properties ◽  
Inland Ice

Changes at the grounding line of ice streams have consequences for inland ice dynamics and hence sea level. Despite substantial evidence documenting upstream propagation of frontal change, the mechanisms by which these changes are transmitted inland are not well understood. In this vein, the frequency response of an idealized ice stream to periodic forcing in the downstream strain rate is examined for basally and laterally resisted ice streams using a one-dimensional, linearized membrane stress approximation. This reveals two distinct behavioural branches, which we find to correspond to different mechanisms of upstream velocity and thickness propagation, depending on the forcing frequency. At low frequencies (centennial to millennial periods), slope and thickness covary hundreds of kilometres inland, and the shallow-ice approximation is sufficient to explain upstream propagation, which occurs through changes in grounding-line flow and geometry. At high frequencies (decadal to sub-decadal periods), penetration distances are tens of kilometres; while velocity adjusts rapidly to such forcing, thickness varies little and upstream propagation occurs through the direct transmission of membrane stresses. Propagation properties vary significantly between 29 Antarctic ice streams considered. A square-wave function in frontal stress is explored by summing frequency solutions, simulating some aspects of the dynamical response to sudden ice-shelf change.

Quasi-Periodic Oscillations in Dwarf Novae

1979 ◽  
Vol 46 ◽  
pp. 77-88
Author(s):  
Edward L. Robinson
Keyword(s):  
Binary Systems ◽  
Outer Edge ◽  
Light Curves ◽  
Close Binary ◽  
Bright Spot ◽  
Dwarf Novae ◽  
Periodic Oscillations ◽  
High Frequencies ◽  
Short Period ◽  
Typical Time

Three distinct kinds of rapid variations have been detected in the light curves of dwarf novae: rapid flickering, short period coherent oscillations, and quasi-periodic oscillations. The rapid flickering is seen in the light curves of most, if not all, dwarf novae, and is especially apparent during minimum light between eruptions. The flickering has a typical time scale of a few minutes or less and a typical amplitude of about .1 mag. The flickering is completely random and unpredictable; the power spectrum of flickering shows only a slow decrease from low to high frequencies. The observations of U Gem by Warner and Nather (1971) showed conclusively that most of the flickering is produced by variations in the luminosity of the bright spot near the outer edge of the accretion disk around the white dwarf in these close binary systems.

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