kHz Sampling Rate Research Articles

The presence of low‐frequency narrowband phonations in the wild bottlenose dolphins’ acoustic repertoire.

Bottlenose dolphins’ phonations are commonly divided into three major categories: whistles, echolocation clicks, and burst pulses. Other categories are often mentioned and described as yelps, squawks, barks, and low‐frequency narrowband sounds. Here, we report the occurrence of low‐frequency tonal phonations with fundamental frequency within the 500–2000 Hz range, accompanied by numerous harmonics. Recordings were made using 48 and 192 kHz sampling rates and a 100 Hz high‐pass filter in the presence of free‐ranging bottlenose dolphins in Mississippi Sound, MS. Auditory sensitivity of the bottlenose dolphins has been studied extensively, and the results indicate that dolphins have their best hearing sensitivity in the higher‐frequency range (15–110 kHz). Low‐frequency sounds (above 75 Hz) can be detected as well, and it has been suggested that this detection mechanism may be entirely different from that used for higher frequencies and may even include mechanoreception. The occurrence of low‐frequency phonations in wild dolphins indicates that low‐frequency detection may play an important role in the animals’ everyday activities.

Filterscopes: Spectral line monitors for long-pulse plasma devices

A photomultiplier (PMT)-based diagnostic system for monitoring spectral lines along multiple viewchords, named the "Filterscope" [R. J. Colchin et al., Rev. Sci. Instrum. 74, 2068 (2003)], is currently in use at the DIII-D, NSTX, and CDX-U fusion plasma devices in the US, and has been installed at the KSTAR device in Korea. This diagnostic has recently been upgraded for application to long-pulse devices, such as KSTAR, EAST in China, and the future ITER in France. A new data acquisition system, employing the PXI instrumentation platform with an embedded Windows microprocessor controller, can simultaneously record up to 72 channels at 100 kHz sampling rates for plasma periods lasting up to 20 min. Based on the average signal level during an adjustable time interval (100 ms in the present DIII-D implementation), the controller digitally adjusts PMT dynode voltage throughout the course of a discharge, thereby maintaining the output signals at a level where they are neither saturated nor dominated by digitizer noise. The new system's ability to accommodate large variations in source strength, discharge to discharge and within a single discharge, has proved particularly valuable during DIII-D operations, since changes between top, bottom, and double-null divertor magnetic configurations lead to large temporal variations in signal brightness.

A low noise remotely controllable wireless telemetry system for single-unit recording in rats navigating in a vertical maze

The use of cables for recording neural activity limits the scope of behavioral tests used in conscious free-moving animals. Particularly, cable attachments make it impossible to record in three-dimensional (3D) mazes where levels are vertically stacked or in enclosed spaces. Such environments are of particular interest in investigations of hippocampal place cells, in which neural activity is correlated with spatial position in the environment. We developed a flexible miniaturized Bluetooth-based wireless data acquisition system. The wireless module included an 8-channel analogue front end, digital controller, and Bluetooth transceiver mounted on a backpack. Our bidirectional wireless design allowed all data channels to be previewed at 1 kHz sample rate, and one channel, selected by remote control, to be sampled at 10 kHz. Extracellular recordings of neuronal activity are highly susceptible to ambient electrical noise due to the high electrode impedance. Through careful design of appropriate shielding and hardware configuration to avoid ground loops, mains power and Bluetooth hopping frequency noise were reduced sufficiently to yield signal quality comparable to those recorded by wired systems. With this system we were able to obtain single-unit recordings of hippocampal place cells in rats running an enclosed vertical maze, over a range of 5 m.

Comparison of automatic classification methods for beluga whales vocalizations

The beluga whale is a loquacious marine mammal with a complex vocal repertory. It produces a wide variety of whistles and pulsed tones as well as high‐frequency echolocation clicks. Automatic detection of the long‐distance propagating communication calls are desirable for implementing passive acoustic monitoring (PAM) systems in their environment, for habitat utilisation studies and real‐time early warning devices in anthropogenic impact mitigation systems. Signal processing methods were developed to classify beluga vocalizations from a PAM data set recorded in Cap‐de‐Bon‐Désir in the Saguenay‐St. Lawrence Marine Park in summer 2003 using a 6‐hydrophones array with a 10‐100 kHz sampling rate. The performance of an MFCC‐based HMM system and a polynomial model applied to extracted time‐frequency contours of vocalizations will be evaluated. The feasibility of real‐time implementation will then be analysed for both methods.

Non stationary tire‐road noise analysis using large array beam forming in the time and frequency domains

In the framework of the REBECA Project founded by the ADEME, one seeks to provide a description of the tire‐road noise source from the exterior of the vehicle perspective. Far field acoustic imaging techniques were proposed to identify the sources. Therefore an optimised array of 120 microphones, 4 m in diameter, was modelled and built. Measurements of the noise produced by a car mounted on a roll were performed in a semi anechoic room. The front car axle was driven at various constant speeds and to rising speeds as well. Beam formed images and point signals have been post‐processed with a 125 kHz sampling rate in order to derive space and time analysis of the pressure field in the vicinity of the tire‐roll contact point. The high rate movies processed clearly exhibit periodic phenomena generated around the contact point, while the tire structure borne source appears to be insignificant. Results of frequency and order analysis are also presented in this attempt to provide an interpretation of the tire/roa...

Wireless telemetry system for single‐unit recording in rats navigation

The use of cable systems for neural activity recording limits the measure of behavioral tests in conscious free‐moving animals. In particular, cable attachments make it difficult to solve the challenge of a wired measurement system in enclosed spaces such as tunnels or closure mazes. Such environments are of particular interest in investigations of hippocampal place cells, in which neural activity is correlated with spatial position in the environment. In this study, we developed a flexible miniaturized Bluetooth‐based wireless data acquisition system and validated it in single‐unit recordings of place cells in rats running an enclosed environment over a range of 5 m. The wireless module included an 8‐channel analogue front end, digital controller, and Bluetooth transceiver mounted on a backpack. Our flexible bidirectional wireless design allowed all data channels to be previewed at 1 kHz sample rate, and one channel, selected by remote control, to be sampled at 10 kHz. Through careful hardware design, appropriate shielding and avoiding ground loops, interferences from power line and Bluetooth hopping frequency were reduced sufficiently to yield signal quality comparable to that recorded by wired systems. Bluetooth technology thus offers a novel solution for telemetry systems to enable cable‐free recordings of place cells.

Measurement of Reinforcement Corrosion Rate Using Transient Galvanostatic Pulse Method

Corrosion rate evaluation of concrete structure steel reinforcement was performed through investigation of a galvanostatic pulse transient response technique. A number of short sections of concrete embedded steel bar were used to conduct measurement of galvanostatic pulse transient measurements. There was a 30 to 180 second variation in applied galvanostatic pulse duration. A typical 1 kHz sampling rate was used to investigate the resulting transient potential response. To obtain separate equivalent electronic components, comprising a capacitance and resistance series, with reinforcing steel corrosion condition dependent values, there was analysis of the electrochemical potential transient response. Separate resistive components summation allowed evaluation of corrosion rate, which was then compared with a conventional linear polarization resistance (LPR) measurement corrosion rate on the same specimens. That the galvanostatic pulse transient technique enables resolution of the separate polarization resistance components, which provides a more conservative ongoing corrosion rate evaluation and offers significant advantages over either the galvanostatic or potentiostatic LPR method, is shown by obtained results.

Radio-frequency plasma transducer for use in harsh environments

We describe a compact transducer used to generate and modulate low-intensity radio-frequency atmospheric pressure plasma (RF-APP) for high temperature gap measurement and generation of air-coupled ultrasound. The new transducer consists of a quarter-wave transmission line where the ground return path is a coaxial solenoid winding. The RF-APP is initiated at the open end of the transmission line and stabilized by passive negative feedback between the electrical impedance of the plasma and the energy stored in the solenoid. The electrical impedance of the plasma was measured at the lower-voltage source end of the transducer, eliminating the need to measure kilovolt-level voltages near the discharge. We describe the use of a 7 MHz RF-APP prototype as a harsh-environment clearance sensor to demonstrate the suitability of plasma discharges for a common nondestructive inspection application. Clearance measurements of 0-5 mm were performed on a rotating calibration target with a measurement precision of 0.1 mm and a 20 kHz sampling rate.

Alterations in the Brain–Gut Axis Underlying Visceral Chemosensitivity in Nippostrongylus brasiliensis-Infected Mice

Visceral hypersensitivity, a hallmark of irritable bowel syndrome, is generally considered to be mechanosensitive in nature and mediated via spinal afferents. Both stress and inflammation are implicated in visceral hypersensitivity, but the underlying molecular mechanisms of visceral hypersensitivity are unknown. Mice were infected with Nippostrongylus brasiliensis (Nb) larvae, exposed to environmental stress and the following separate studies performed 3-4 weeks later. Mesenteric afferent nerve activity was recorded in response to either ramp balloon distention (60 mm Hg), or to an intraluminal perfusion of hydrochloric acid (50 mmol/L), or to octreotide administration (2 micromol/L). Intraperitoneal injection of cholera toxin B-488 identified neurons projecting to the abdominal viscera. Fluorescent neurons in dorsal root and nodose ganglia were isolated using laser-capture microdissection. RNA was hybridized to Affymetrix Mouse whole genome arrays for analysis to evaluate the effects of stress and infection. In mice previously infected with Nb, there was no change in intestinal afferent mechanosensitivity, but there was an increase in chemosensitive responses to intraluminal hydrochloric acid when compared with control animals. Gene expression profiles in vagal but not spinal visceral sensory neurons were significantly altered in stressed Nb-infected mice. Decreased afferent responses to somatostatin receptor 2 stimulation correlated with lower expression of vagal somatostatin receptor 2 in stressed Nb-infected mice, confirming a link between molecular data and functional sequelae. Alterations in the intestinal brain-gut axis, in chemosensitivity but not mechanosensitivity, and through vagal rather than spinal pathways, are implicated in stress-induced postinflammatory visceral hypersensitivity.

Anomalyous interaural coherence minima near 45 degrees

High‐resolution (200 kHz sample rate) measurements of interaural coherence for a KEMAR manikin were made in an anechoic environment. As the angle of incident sound was varied in the horizontal plane, there was a minimum in coherence around ±45°. These coherence minima occured at low frequencies, up to about 3000 Hz, and decreased in depth for increasing frequency, f, at a rate approximately proportional to 1/f. In a 1/3‐octave band centered at 500 Hz, the interaural coherence was approximately 0.7 for angles of ±45°. These results were confirmed by measurements in KEMAR using probe microphones. Measurements made using probe microphones with human listeners at angles of ±45° and 0° showed a similar pattern in coherences, but the minima were far more shallow. In the 500 Hz band, a coherence of, on average, 0.94 was measured in listeners facing ±45°, compared to an average coherence of 0.99 in that band at 0°. Headphone experiments using measured values of coherence showed that the deeper measured coherence minima lead to a deficit in sound localization. [Work supported by the NIDCD grant DC00181.]

A Taste Receptor Required for the Caffeine Response In Vivo

Caffeine is a methylxanthine present in the coffee tree, tea plant, and other naturally occurring sources and is among the most commonly consumed drugs worldwide. Whereas the pharmacological action of caffeine has been studied extensively, relatively little is known concerning the molecular mechanism through which this substance is detected as a bitter compound. Unlike most tastants, which are detected through cell-surface G protein-coupled receptors, it has been proposed that caffeine and related methylxanthines activate taste-receptor cells through inhibition of a cyclic nucleotide phosphodiesterase (PDE) . Here, we show that the gustatory receptor Gr66a is expressed in the dendrites of Drosophila gustatory receptor neurons and is essential for the caffeine response. In a behavioral assay, the aversion to caffeine was specifically disrupted in flies missing Gr66a. Caffeine-induced action potentials were also eliminated, as was the response to theophylline, the methylxanthine in tea. The Gr66a mutant exhibited normal tastant-induced action potentials upon presentation of theobromine, a methylxanthine in cocoa. Given that theobromine and caffeine inhibit PDEs with equal potencies , these data further support the role of Gr66a rather than a PDE in mediating the caffeine response. Gr66a is the first gustatory receptor shown to be essential for caffeine-induced behavior and activity of gustatory receptor cells in vivo.

High-speed gas sensor for chemosensory event-related potentials or magnetic fields

The observation of odor and air exchange with high temporal accuracy is necessary to obtain strict chemosensory event-related potentials (CSERPs) or magnetic fields, as proposed by Evans et al. [Evans W, Kobal G, Lorig T, Prah J. Suggestions for collection and reporting of chemosensory (olfactory) event-related potentials. Chem Senses, 1993; 18: 751– 6]. No suitable method for real time observation of gas stimuli, however, has been available until now. We have developed a technique to measure accurately gas molecule concentrations with a high temporal resolution. We determined that attenuation of sound amplitude varies in a manner dependent on the average molecular weight through which the sound wave passes. Based on this principle, we have designed a high-speed gas concentration sensor utilizing ultrasound. We investigated the practical potential of this sensor using a chemosensory stimulator (olfactometer); we succeeded in observing rapid gas exchange between air and nitrogen with a 2 kHz sampling rate. The signal/noise ratio of the stimulus was greater than 42 dB. In a 20 min experiment we determined that, for this olfactometer, the gas onset latency was 79 ms and the rise time was 16 ms. No significant artifact to magnetic fields was observed, even when the sensor was situated near a whole head magnetoencephalography (MEG) system. These results indicate that this sensor could be used for the observation of odor and air exchange, as well as, for real time monitoring of odor stimuli during actual experiments with a participant.

Does intonation have primitive units?

This study investigated whether listeners can interpret intonation based on partial rather than global fundamental frequency (F0) or pitch information. Matched Statements and echo questions were recorded digitally at 22 kHz sampling rate using a Computerized Speech Lab (CSL). Each production was stored on the CSL and edited by slicing the wave form into two parts that corresponded to terminal (last 150–200 ms span of the F0 contour) and preterminal (section of contour preceding the terminal region) F0 contour regions. A total of 92 stimuli was thus generated and recorded on a DAT tape. The tape was played to 96 young (20–28 years) and old (42–79 years) adults to determine if each stimulus was part of a statement or a question. For preterminal (PTL) stimuli, both groups successfully identified statements 91% and 88% of the time, respectively, compared to 72% each for questions. The respective scores for the terminal (TL) stimuli were 94% and 91% (statements) versus 91% and 87% (questions). Across groups, statements were easier to identify with both TL (p=0.002) and PTL (p=0.001) cues compared to questions. These findings suggest that intonation decoding might involve units smaller than global F0 contour. [Work supported by NIH (NIDCD) grant 5R03DC04955-02.]

First results on GOMOS/ENVISAT

Global ozone monitoring by occultation of stars (GOMOS) on ENVISAT is the first space instrument dedicated to the study of the atmosphere of the Earth by the technique of stellar occultations (global ozone monitoring by occultation of stars). From a polar orbit, it allows to have a good latitude coverage. Because it is self-calibrated, it is particularly well adapted to the long time trend monitoring of stratospheric species. With four spectrometers the wavelength coverage of 245–942 nm allows to monitor ozone, H 2O, NO 2, NO 3, air, aerosols, O 2 and the temperature profiles. Two additional fast photometers (1 kHz sampling rate) allow for the correction of scintillations, as well as a study of the turbulence regime. A high vertical resolution profile of the temperature may also be obtained from the time shift between the red and the blue photometer. The first results of GOMOS are presented and ozone measurements compared to other sources.

A novel fuzzy-logic-based phase selection technique for power system relaying

Fast tripping and consequent single-pole auto-reclosure of the faulted phase for single-phase earth faults is extensively used in long line applications. Traditional phase selection techniques can suffer some drawbacks due to their dependency on varying system and fault conditions. However, with the advent of fuzzy-logic techniques, and their ability to map complex and non-linear power system configurations provide a very attractive solution to accurate and fast phase selection procedure. This paper presents a new approach to real-time phase selection in power transmission systems using fuzzy-logic-based multi-criteria approach. Only the three line currents are utilised to detect the faulted phase. An online wavelet-based pre-processor stage [IEEE Trans. Power Delivery, 18 (4) (2003) 1158; IEEE Trans. Power delivery 17(4) (2002) 908; IEEE Trans. Power Delivery, 18 (1) (2003) 170; Paper # 01TD069, IEEE T&D Conference, 28 October–2 November 2001, Atlanta, GA] is used with 10 samples data window (based on 4.5 kHz sampling rate and 50 Hz power frequency). The paper demonstrates the multi-criteria algorithm that is based on fuzzy sets for the decision making part of the scheme. Computer simulation have been conducted using EMTP programs. Results proved that the correct detection is achieved in less than half a cycle and that computational burden is simpler than the recently postulated phase selection techniques, and this approach can be used as an effective tool for high speed digital relaying.

Software-centered implementation of 128 channel huge speaker array with stock PC

A huge speaker array system of 128 loudspeakers was constructed and experimented. It was implemented as ‘‘software-centered’’ style utilizing stock loudspeakers and a PC. No dedicated hardware nor DSP was utilized. Spot forming, instead of beam forming, could be realized by 32 by 4 square layout of the array. Spot means small area of higher sound pressure level. Number of the spot was not limited to one. In the experiment, within 3 m by 3 m area, four spots of different sounds could be simultaneously formed. This spot forming was confirmed by actually measured spatial distribution of sound pressure level. The effect of the spot was also confirmed auditorily. Since the system was software-centered, it was dynamic. By simply changing software parameters, location of the spot can be easily moved even while the system was running. This movability of the spot was intended to be basis for visual steering. To realize the system, a simultaneous 128 channel 14-bit DA converter PCI board was developed. 44.1 kHz sampling rate was achieved by 2.4-GHz Intel Xeon-based PC utilizing the DA board and a real-time OS, named ART-Linux. Approximately 23-μs loop could be realized by software. It was the world’s fastest software loop.

Bow response to the string it is bowing

The force that a bowed string exerts on the bow can be reconstructed from the forces on the string’s termination. By using one or more accelerometers attached to the bow, the response of the bow to that reconstructed force can be recorded. Bow responses will be shown that were obtained using a bowing machine. At some harmonic frequencies of the string the signal from the longitudinal standing wave excited on the bow hair allows determination of the velocity of propagation of that wave. The consequence of the variable excitation of various harmonics of the standing wave as the bow stroke progresses is a rapidly changing excitation of the bows various normal modes. Three data channels, requiring at least a 128 kHz sampling rate for E-strings, are required for bow force reconstruction and motion detection of the bow. The validity of substituting the force of the string on the bridge instead of the reconstructed bow force is explored. That allows a reduction of the minimum number of data channels from three to two, a reduction in the necessary sampling rate, and use of a bow stroke by a player instead of a bowing machine.

Flow-induced vibration testing of replacement thermowell designs

Inconel 600 Primary Water Stress Corrosion Cracking (PWSCC) in Nuclear Pressurized Water Reactors (PWRs) has necessitated the repair/replacement of various small bore nozzles. These repairs/replacements must be designed to avoid unwanted vibrations. So, to this end, new RTD-Thermowell-Nozzle replacement designs were developed and subjected to flow testing over a velocity range from 9.14 to 33.53 m/s (30–110 ft/s), and temperatures ranging from 121°C to 316°C (250–600°F). The replacement nozzles are welded on the pipe OD, rather than on the pipe ID. A split, tapered ferrule is used to support the nozzle tip inside the pipe bore. This maintains high thermowell tip-resonance frequencies with the objective of avoiding self-excitation from vortex shedding that is believed to have caused failures in an earlier design during initial, precritical plant startup testing. The flow testing was complicated by the small size of the thermowell tips (5.08 mm or 0.2 in ID), which necessitated use of a complement of low temperature and high temperature instrumentation. Since the high temperature device had an internal resonance (750 Hz) within the frequency range of interest (0–2500 Hz), adequate sensor correlations had to be derived from low temperature tests. The current nozzle/thermowell design was tested concurrently with two slight variations of the replacement design. The acceleration signals were acquired during incremental and continuous flow sweeps, nominally at 5 kHz sampling rates and for time domain processing as high as 25 kHz. Whereas vortex-shedding frequencies were predicted to prevail between 400 and 1500 Hz, no such response was observed at these frequencies. Rather, the thermowell tips responded due to turbulent buffeting with a peak response that was related directly to flow velocity. Lift direction response was always larger than drag direction response. The thermowell tips also responded at their natural tip frequencies in a narrow band random fashion. At the higher flow rates, one replacement design experienced an instability mode leading to high tip stresses. Although this instability did not repeat, this particular design was eliminated from consideration. The second replacement design performed almost identically to the current in-plant design. The experimental data were used to extract forcing functions and thermowell responses that were used as input into the design calculations.

Loss-less data acquisition system for SST-1

SST-1 being steady-state Tokamak having a discharge duration of 1000 s demands a data acquisition system (DAS) which is capable enough to acquire data loss lessly from slow diagnostics. The needs of loss-less continuous acquisition have a significant effect on selection of acquisition hardware. The evolution of DAS for steady-state operation of Tokamaks has been technology-driven. The paper describes the various needs of SST diagnostics and our selection of the most suitable configuration for long-duration discharges. Here PXI bus, which is an extension of the widely accepted PCI bus, has been evaluated on the most commonly used platform like Windows with normally available PCs. For slow diagnostics, the PXI-based system with 48 channels was evaluated for continuous, single-shot and windowed acquisition. In the case of continuous acquisition, it acquires data from 48 channels at 10 kHz sampling rate and pushes all the 48 data channels on the network as well as writing to the hard disk simultaneously. A client utility also has been developed to view the data from any network node.

A modified wavelet-based fault classification technique

This paper presents a new Wavelet-based fault classification technique that utilises the HF components confined to scale-8 (level-3) of Wavelet analysis of the three line currents in transmission line. Data window required for the algorithm is small (less than half power frequency cycle based on 1.0 kHz sampling rate). In the paper firstly the theoretical background is reported and briefly discussed in relation to reference ‘IEEE, T&D Conf. (2001)’. Then, an extended study is conducted, and the proposed method is described in detail. Finally, some case studies are examined using the emtp and matlab softwares in order to highlight the performance of the method. It is proved that the proposed technique is reliable and appropriate for real-time measurement algorithms and fault classification techniques.