bluuebunny/crossref_metadata_2025 huggingface dataset:
Very long-range source localization with a small vertical array
Authors: Heaney Kevin D. , Kuperman W. A.
Published: July 2002

Several processors are developed and used to perform source localization on the 3250-km San Diego–Hawaii path of the Acoustic Engineering Test (AET). Associated simulations are done to test the range-frequency limits of coherent matched-field processing using PE modeling through a simulated internal-wave environment. The AET experiment is presently well beyond the range of effective coherent matched-field processing. A mode filter was developed to extract 60 complex mode amplitudes from the data received on the 20-element vertical line array. A mode space depth estimator successfully localizes the source. A mode arrival time difference range estimator is developed and found to be biased by internal-wave induced mode coupling. The final processor developed utilizes the stability of early arriving wavefronts to determine the source range by matching wavefront arrival patterns.
Loudness perception and frequency discrimination in subjects with steeply sloping hearing loss: Possible correlates of neural plasticity
Authors: McDermott Hugh J. , Lech Margaret , Kornblum Michelle S. , Irvine Dexter R. F.
Published: July 2002

Loudness functions and frequency difference limens (DLFs) were measured in five subjects with steeply sloping high-frequency sensorineural hearing loss. The stimuli were pulsed pure tones encompassing a range of frequencies. Loudness data were obtained using a 2AFC matching procedure with a 500-Hz reference presented at a number of levels. DLFs were measured using a 3AFC procedure with intensities randomized within 6 dB around an equal-loudness level. Results showed significantly shallower loudness functions near the cutoff frequency of the loss than at a lower frequency, where hearing thresholds were near normal. DLFs were elevated, on average, relative to DLFs measured using the same procedure in five normally hearing subjects, but showed a local reduction near the cutoff frequency in most subjects with high-frequency loss. The loudness data are generally consistent with recent models that describe loudness perception in terms of peripheral excitation patterns that are presumably restricted by a steeply sloping hearing loss. However, the DLF data are interpreted with reference to animal experiments that have shown reorganization in the auditory cortex following the introduction of restricted cochlear lesions. Such reorganization results in an increase in the spatial representation of lesion-edge frequencies, and is comparable with the functional reorganization observed in animals following frequency-discrimination training. It is suggested that similar effects may occur in humans with steeply sloping high-frequency hearing loss, and therefore, the local reduction in DLFs in our data may reflect neural plasticity.
Fluid flow in a dynamic mechanical model of the vocal folds and tract. II. Implications for speech production studies
Authors: Shadle Christine H. , Barney Anna , Davies P. O. A. L.
Published: July 2002

A companion paper [Barney et al., J. Acoust. Soc. Am. 105, 444–455 (1999)] presents measurements in a dynamic mechanical model (the DMM) of the vocal folds and vocal tract: It was shown that closer prediction of the radiated sound pressure was possible when nonacoustic (vortical) as well as acoustic components of the velocity in the duct were included. In this paper, using such a simple geometry to model the vocal tract is justified by comparing acoustic and aerodynamic measurements in the DMM to those made in vivo: sub- and supraglottal pressures, radiated pressure, and hot wire velocities. The DMM produces sound equivalent to weak, low-frequency falsetto. A Rothenberg mask was then placed on the end of the DMM, and two estimates of the glottal waveform were compared to velocities measured near the “glottis.” The results show that the glottal waveform does not resemble any hot wire velocities measured near the shutters; travel times for acoustic and nonacoustic components of the velocity field differ significantly, which may cause problems when using the Rothenberg mask to analyze transients; the mask itself alters the acoustic field in the duct, and the radiated pressure, significantly. The evidence points toward the existence of a vortex train during and caused by phonation, and significant sound generation due to the interaction of that train with tract boundaries; these findings indicate that the models on which inverse filtering are based have been overgeneralized.
Acoustic pursuit of invisible moving targets by cats
Authors: Beitel Ralph E.
Published: July 2002

Head movements evoked by an invisible acoustic target were used as a metric to analyze localization of moving sources of sound in naive cats. The target was presented in the lateral sound field and moved along an arc at constant angular speeds. Head-movement trajectories were characterized by a large-magnitude orienting component that undershot the target, and a tracking component elicited by the target during acoustic pursuit. The tracking component was characterized by a succession of stepwise head movements that maintained a relatively close alignment of the median plane of the head with the moving acoustic target.
Behavior of piano-action in a grand piano. I. Analysis of the motion of the hammer prior to string contact
Authors: Hayashi Eiji , Yamane Masami , Mori Hajime
Published: July 2002

Producing a stable soft tone, difficult even for pianists, is one of the critical challenges in the development of an automatic piano. The motion of the hammer prior to string contact was studied to provide a basis for creating a stable, soft tone. A simple dynamic mechanical model was used to analyze the motion. Using the actuator developed for the touch system, the motion of the hammer under various input waveforms was observed and recorded. Based on this analysis, it can be said that the calculated behavior correlates with the measured behavior. These results indicate that the proposed model is useful because it clearly illustrates the behavior of the hammer. The modified constant speed necessary to produce an optimum touch input waveform has now been found, which allows the system to achieve stable soft tones.
Blowing pressure, power, and spectrum in trumpet playing
Authors: Fletcher N. H. , Tarnopolsky A.
Published: July 2002

Measurements of sound output as a function of blowing pressure are reported for a group of experienced trumpet players. The study identifies several common features, namely (1) a threshold blowing pressure approximately proportional to the frequency of the note being played, (2) an extended region in which the sound output rises by about 15 dB for each doubling of blowing pressure, and (3) a saturation region in which sound output rises by only about 3 dB for a doubling of blowing pressure. Some players are able to blow with maximum pressures as high as 25 kPa, which is significantly greater than normal systolic blood pressure. A simple theory is presented that provides a physical explanation for the acoustical behavior, but a detailed treatment requires solution of the nonlinear coupled equations both for the lip-valve mechanism and for nonlinear wave propagation in the instrument tube. Frequency analysis of the sound shows a basic spectral envelope determined by the resonance properties of the mouthpiece cup and the radiation behavior of the bell, supplemented by an extension to increasingly high frequencies as the blowing pressure is increased. This high-frequency behavior can be attributed to nonlinear wavefront steepening during sound propagation along the cylindrical bore of the instrument.
Hypothesis testing for geoacoustic environmental models using likelihood ratio
Authors: Mecklenbräuker Christoph F. , Gerstoft Peter , Böhme Johann F. , Chung Pei-Jung
Published: July 2002

A generalized likelihood ratio test is developed for testing acoustic environmental models with an application to parameter inversion using an acoustic propagation code. The signal-to-noise ratio in acoustic measurements proves to limit the details on geoacoustic environments that can be determined by matched field processing methods. A hypothesis test serves in Monte Carlo simulations as a tool to determine minimal signal levels for the bottom parameter inversion. The term “hierarchy of models” is used for denoting a sequence of models in which each particular model contains all previous ones. For determining the model order and its parameters, a combined parameter estimation and multiple sequential test is proposed. Given the observed data, how many parameters should be included in the model? The last question is important for the order selection in hierarchies of models with an increasing number of parameters. Multiple sequential hypotheses testing provides a procedure to determine the model order in a statistically justified way. Monte Carlo simulations show the behavior of the test for selecting a model order as a function of the signal-to-noise (SNR) ratio. The test is applied to broadband data measured using a vertical array near the island of Elba in the Mediterranean Sea and compared with Akaike’s Information Criterion.
Low-frequency shear wave propagation in periodic systems of alternating solid and viscous fluid layers
Authors: Gurevich Boris
Published: July 2002

Waves in periodic layered systems at low frequencies can be studied using an asymptotic analysis of the Rytov’s exact dispersion equations. Since the wavelength of the shear wave in the fluid (viscous skin depth) is much smaller than the wavelength of the shear wave in the solid, the presence of viscous fluid layers requires a consideration of higher terms in the asymptotic expansions. For a shear wave with the directions of propagation and of particle motion in the bedding plane, the attenuation (inverse Q) obtained by this procedure is Q−1=ωηφ/μs(1−φ)+ωφρf2hf2/12ρη+o(ω), where ω is frequency, ρ is weighted average density of the solid/fluid system, hf is the thickness of fluid layers, φ is fluid volume fraction, i.e., the “porosity,” μs is solid shear modulus, and ρf and η are the density and viscosity of the fluid, respectively. The term proportional to η is responsible for the viscous shear relaxation, while the term proportional to η−1 accounts for the visco-inertial (poroelastic) attenuation of Biot’s type. This result shows that the characteristic frequencies of visco-elastic ωVE, poroelastic ωB, and scattering ωR attenuation mechanisms obey the relation ωVEωB=ωR2, which explains why the visco-elastic and poroelastic mechanisms are usually treated separately in the context of macroscopic theories that imply ω≪ωR. The poroelastic mechanism dominates over the visco-elastic one when the frequency-independent parameter B=ωB/ωVE=12η2/μsρfhf2≪1, and vice versa.
The beam forming properties of a concave spherical reflector with an on-axis receiver
Authors: Deane Grant B.
Published: July 2002

A wave-theoretical formulation for the on-axis scattering of a concave, spherical reflector with a pressure release surface is presented. Expressions for the reflector gain and half-power beam width are derived using a stationary phase analysis of the radiation integral arising from the Kirchhoff–Helmholtz scalar diffraction theory. The gain is shown to scale with frequency and the beam width scales inversely with frequency. The results of the analysis compare well with data collected from a 3-m spherical dish in both air and underwater calibrations.
Full-wave simulation of the forward scattering of sound in a structured ocean: A comparison with observations
Authors: Wolfson Michael A. , Spiesberger John L.
Published: July 2002

Between 1983 and 1989, acoustic pulse-like signals at 133-Hz, 60-ms resolution, were transmitted from Oahu to Northern California. Analysis of the data indicates that the early arriving, steep paths are stable over basin scales, whereas the late, near-axial paths are sensitive to ocean structure. The late paths undergo vertical scattering on the order of the acoustic waveguide, i.e., 1 km [J. Acoust. Soc. Am. 99, 173–184 (1996)]. The parabolic approximation is used to simulate pulse propagation over the vertical plane connecting the source and receiver. Several prescriptions are used for the speed of sound: (1) Climatologically averaged sound speed with and without a realization of internal waves superposed; (2) Measured mesoscale structure with and without a realization of internal waves superposed. The spectrum of the internal waves is given by Garrett and Munk. Modeled internal waves and the measured mesoscale structure are sufficient to explain the vertical scattering of sound by 1 km. The mesoscale structure contributes a travel time bias of 0.6 s for the late multipath. This bias is seen to be a relevant contribution in accounting for the travel times of the last arrival.
Masking by harmonic complexes with different phase spectra in hearing-impaired listeners
Authors: Lentz Jennifer J. , Leek Marjorie R.
Published: July 2002

At the last meeting, we showed that in normal-hearing listeners, masking effectiveness of harmonic complexes depends on the maskers’ phase spectra. Such masking differences are thought to partially reflect an interaction between the input waveform and phase characteristics of the normal auditory system. We have extended that work to explore masking by harmonic complexes in listeners with hearing impairment. The masker was a harmonic complex with equal-amplitude components, with phases selected according to scaled modifications of the Schroeder algorithm. Masking was measured for several different signal frequencies and levels. In contrast to normal-hearing listeners, most hearing-impaired listeners showed little change in masking for different phase selections. Some listeners did demonstrate masking differences, but the greatest reduction in masking occurred when the components had nearly equal phases (i.e., a highly modulated masker waveform). Apparently, in those listeners, the within-channel phase characteristic did not substantially alter the phase structure of the input stimulus, as is thought to occur in normal ears. In aggregate, these data suggest that sensorineural hearing loss is accompanied by deficits in temporal resolution, possibly involving changes in the phase characteristics of auditory channels. [Work supported by NIH DC00626.]
Sound propagation over concave surfaces
Authors: Wang Qiang , Li Kai Ming
Published: July 2002

Diffraction of sound by concave surfaces is investigated theoretically and experimentally. In an earlier study [J. Acoust. Soc. Am. 104, 2683–2691 (1998)], it has been demonstrated that a rigorous analogy exists for the sound field above a convex circular cylinder in an otherwise homogeneous medium. The predicted sound field corresponds to the situation where the sound speed of the medium decreases exponentially with height. Extending the previous work, this paper investigates of the sound field above a concave surface and explores the corresponding analogy. Normal mode solutions have been developed for a downward refracting medium with an exponential sound speed profile. The solutions are used to predict the sound fields diffracted by a cylindrical concave surface. A series of laboratory experiments is conducted using point monopole, horizontal dipole, and vertical dipole sources over cylindrical concave surfaces. The experimental measurements are compared with the normal mode predictions. For monopole and horizontal dipole sources, good agreement has been found between measurements and the normal mode predictions using an exponential profile. However, the agreement is less satisfactory where the sound field was due to vertical dipole sources.
Spectro-temporal modulation transfer functions and speech intelligibility
Authors: Chi Taishih , Gao Yujie , Guyton Matthew C. , Ru Powen , Shamma Shihab
Published: July 2002

Detection thresholds for spectral and temporal modulations are measured using broadband spectra with sinusoidally rippled profiles that drift up or down the log-frequency axis at constant velocities. Spectro-temporal modulation transfer functions (MTFs) are derived as a function of ripple peak density (Ω cycles/octave) and drifting velocity (ω Hz). The MTFs exhibit a low-pass function with respect to both dimensions, with 50% bandwidths of about 16 Hz and 2 cycles/octave. The data replicate (as special cases) previously measured purely temporal MTFs (Ω=0) [Viemeister, J. Acoust. Soc. Am. 66, 1364–1380 (1979)] and purely spectral MTFs (ω=0) [Green, in Auditory Frequency Selectivity (Plenum, Cambridge, 1986), pp. 351–359]. A computational auditory model is presented that exhibits spectro-temporal MTFs consistent with the salient trends in the data. The model is used to demonstrate the potential relevance of these MTFs to the assessment of speech intelligibility in noise and reverberant conditions.
Normal modes of a radially braced guitar determined by electronic TV holography
Authors: Rossing Thomas D. , Eban Gila
Published: July 2002

Electronic TV holography has been used to determine normal modes of vibration of a classical guitar having an innovative bracing design. The modes observed at frequencies up to 800 Hz are quite similar to those reported in other classical guitars. Observing modes of the air cavity with stationary plates and ribs helps to understand the normal modes of the guitar. Sound spectra indicate the relative sound radiation by the top and back plates at each modal frequency.
Characterization of multiple-sprung masses for wideband noise control
Authors: Maidanik G. , Becker K. J.
Published: July 2002

The design of a wide frequency band neutralizer, vibration absorber and/or structural fuzzy, in the form of multiple-sprung masses, is extensively reported in the open literature. The action of the device is reported in terms of the joint point impedance of the sprung masses. This joint impedance is merely the sum over the impedances of the individual sprung masses at the common point to which the device is to be attached to a master structure. The normalized frequency bandwidth of a device composed of a single-sprung mass is proportional to the loss factor of that sprung mass. To increase this bandwidth, a device composed of more than one sprung mass, with distributed resonance frequencies, is utilized. To keep suppressed the undulations in the joint impedance of a set composed of a multiplicity of sprung masses, the loss factors are rendered larger than the normalized separations between adjacent antiresonance frequencies. This modal overlap condition, together with consideration of weight, are central to the design of the device. The analysis of the device is enriched by considering two distinct distributions of resonance frequencies for each set of sprung masses. Moreover, the ranges and parameters which specify that device are limited to reasonably moderate values; e.g., the useful frequency bandwidth of a given device is limited to one-third of its center frequency and the number of sprung masses in a device is restricted not to exceed one-score. In a set employing the first resonance frequency distribution, as the number of sprung masses is initially increased, an increase in the bandwidth is accompanied by an increase in the level of the joint impedance. As the number of sprung masses is further increased, the bandwidth and the level of the joint impedance become saturated. In a set incorporating the second resonance frequency distribution, an ongoing increase in the bandwidth, as the number of sprung masses increases, is accompanied by an ongoing decrease in the level of the joint impedance. The examination of these and other characteristics in the joint impedance of the sprung masses is provided by data obtained in computer experiments performed on a few selected sets of sprung masses.
Dispersion and absorption of sound in monatomic gases: An extended kinetic description
Authors: Marques Wilson
Published: July 2002

The problem concerning the propagation of plane harmonic waves of small amplitudes in monatomic ideal gases is studied using an extended kinetic model that replaces (in the same manner as in the Bhatnagar–Gross–Krook model) the Boltzmann collision operator with a single relaxation-time term. Numerical results for the speed and attenuation of sound are derived and compared with the experimental data of Meyer and Sessler, Greenspan, and Schotter for monatomic gases. At low frequencies, the correct continuum limits for the absorption and dispersion are recovered, while at high frequencies a complete agreement between theory and experiments is observed.
A basic concept of direct converting digital microphone
Authors: Yasuno Yoshinobu , Riko Yasuhiro
Published: July 2002

An electroacoustic system which directly converts analog acoustic signals to digital electric signals is described. The system consists of a subtractor, a sampling and holding circuit, a sigma–delta modulator as a comparator, an accumulator, and a local direct digital-to-analog converting transducer similar to a typical electronic analog-to-digital converter. The subtractor is an electrostatic device which has a diaphragm, driving electrodes, and a detecting electrode. The surface area of the driving electrodes corresponds to the significant bits in the digital signal, as an electroacoustic digital-to-analog converter. The detecting electrode produces an electrical signal proportional to the displacement of the diaphragm driven by subtracting the received acoustic signal from the electrostatically driven force. This is regarded as a subtractor. The detected signal is amplified and sampled-held and modulated by the sigma–delta procedure and generates a signal of ±1 bit, which is added to the accumulator memory by a high clock frequency. The output of the accumulator is the digital signal output and is also fed to the driving electrodes. A 4-bit conceptual system was developed to affirm this concept.
Informational masking by everyday sounds
Authors: Oh Eunmi L. , Lutfi Robert A.
Published: July 2002

Tone-in-noise detection is severely degraded when only a few spectral components of the noise are presented at random on each trial [Neff and Green, Percept. Psychophys. 41, 409–415 (1987)]. The elevations in threshold are attributed to uncertainty regarding the noise caused by sparse sampling of noise components—informational masking is the term used to describe the result. The present experiment was undertaken to determine how informational masking is affected when sparse sampling is from a set of common everyday sounds instead of noise. On each presentation a different masker waveform of constant total power was synthesized from the magnitude and phase of a fixed number, m, of spectral components (m=2–921 across blocks of trials). The components were selected at random from 1 of 50 common environmental sounds (e.g., baby crying, door slamming, phone ringing), or 1 of 50 samples of Gaussian noise. Masked thresholds for a 1.0-kHz signal in the presence of both types of maskers were obtained using an adaptive, two-interval, forced-choice procedure. Results with noise replicated earlier, results showing largest elevations in threshold for 10–20 sampled components. Results with everyday sounds showed a similar pattern with thresholds elevated above those for noise by as much as 10 dB at the larger values of m. The differences in masked thresholds were systematically related to differences in the ensemble variance of masker spectra, as predicted by a model previously applied to noise [Lutfi, J. Acoust. Soc. Am. 94, 748–758 (1993)]. Not predicted was the result of a subsequent trial-by-trial analysis in which 9–11 dB less masking was observed for samples from everyday sounds rated as easily recognized by listeners. The results suggest that listeners fail to exploit lawful dependencies among spectral components of everyday sounds to aid detection, unless enough information is available for the sound to be easily recognized.
Structural radiation mode sensing for active control of sound radiation into enclosed spaces
Authors: Cazzolato Ben S. , Hansen Colin H.
Published: July 2002

In the recent article by Cazzolato and Hansen [J. Acoust. Soc. Am. 104, 2878–2889 (1998)] it was shown that it is possible to derive for a structure some set of surface velocity distributions, referred to as radiation modes, which are orthogonal in terms of their contributions to the acoustic potential energy of a coupled cavity. The technique used an orthonormal decomposition to derive an expression for the radiation modes which was based on prior work for free-field sound radiation. It will be shown in the following letter that for the special case involving the calculation of global internal potential energy it is possible to use a simple approach which requires no orthonormal decomposition since the expression for the global potential energy is already in a form that can be easily diagonalized.
Acoustics of a flanged cylindrical pipe using singular basis functions
Authors: Amir N. , Matzner H. , Shtrikman S.
Published: July 2002

The problem of acoustic radiation from a cylindrical pipe with an infinite flange has been discussed in a number of papers. The most common approach is to decompose the field inside the pipe over a basis of Bessel functions. A very large number of basis functions is usually required, with a large degree of ripple appearing as an artifact in the solution. In this paper it is shown that a close analysis of the velocity field near the corner yields a new family of functions, which are called “edge functions.” Using this set of functions as test functions and applying the moment method on the boundary between the waveguide and free space, a solution is obtained with greatly improved convergence properties and no ripple.
Performance of some sparseness criterion blind deconvolution methods in the presence of noise
Authors: Broadhead Michael K. , Pflug Lisa A.
Published: July 2002

A comparison of the sparseness (simplicity) norm criterion blind deconvolution methods of Cabrelli and Wiggins is made in order to ascertain relative performance for underwater acoustic transient source signal estimation, especially in the presence of noise. Both methods perform well at high signal-to-noise ratios, producing source estimates that are significant improvements over the original received signal for classification purposes. At moderate and lower SNRs, the Cabrelli method tends to generate results that are superior to the Wiggins method. This is especially true for a damped sinusoid transient source, for which the Wiggins method fails completely at lower SNRs, while the Cabrelli method can still produce good source estimates.
Noninvasive system identification for multichannel broadband active noise control
Authors: Nowlin William C. , Guthart Gary S. , Toth Gregory K.
Published: July 2002

Many real-world applications of active noise control are characterized by transfer functions that vary significantly and unpredictably. The controller’s transfer-function models must adapt to these variations. Presented here is a class of adaptive filters that accomplish quasiperiodic system identification updates for feedforward control by using blocks of input–output histories. The algorithms form a one-dimensional family linking normalized least-mean squares (LMS) adaptive filters and block recursive least-squares, termed “block projection” algorithms, and generalize the noninvasive system identification studied by Sommerfeldt and Tichy. The system identification proceeds noninvasively, producing nonparametric impulse responses. Simulations show that the algorithm’s convergence is faster than that of normalized LMS, even after the additional overhead of computing the update is taken into account. Both the multichannel generalization and application of these algorithms to system identification are novel. Simulations of the algorithms’ performance using measured data are presented here, while experimental results of an implemented algorithm are contained in the companion paper.
Psychoacoustics as the basis for modern audio signal data compression
Authors: Zwicker Tilmann
Published: July 2002

To almost everyone involved in music, whether they create it or listen to it, storing and transmitting music signals is of great importance. Recent progress makes it possible to store audio signals in small files and transmit them with very small transmission bandwidths, so that standardized data compression schemes, such as ATRAC (Adaptive Transform Acoustic Coding) or MP3 (Motion Picture Expert Group Layer 3 Format), are now ubiquitous. Successful development of audio storage and transmission technology has always taken into account how the final receiver of audio signals and final judge of their quality, the human auditory system, can actually appreciate them. For example, standards for frequency response and wow and flutter for analog studio tape recorders were originally designed to satisfy known limits of hearing. The use of digital signal processing to exploit newly discovered intricacies of the auditory system has increased the accuracy with which stored and transmitted audio signals can be tailored to the requirements imposed by our hearing. Such accurate matching provides the basis for highly effective audio-signal data compression. This talk provides an overview of the related idiosyncrasies of human hearing, in particular, masking effects in the frequency and temporal domains.
Shear wave velocity measurements of layered sediment models using radiation impedance
Authors: Kimura Masao
Published: July 2002

Shear wave velocity is important in characterizing surface marine sediments. It was demonstrated that the shear wave velocity in viscoelastic media can be obtained using the value of the frequency at which the radiation reactance becomes zero, and the shear wave velocity of sands can be measured. Moreover, the effect of the size of the radius of the circular vibrating plate on the measured values of shear wave velocities in sands is shown. In this study, the shear wave velocities in layered sediment model are measured. The sediment model is a two-layered model, which is composed of clay as the upper medium and sand or urethane rubber as the lower medium. The effect of the thickness of the upper medium on the measured values of shear wave velocities is also considered.
Alternative mouthpiece design for viewing the lip reed in motion
Authors: Ayers R. Dean , Lodin Michael S.
Published: July 2002

Mouthpieces for stroboscopic viewing of the lip reed have been designed for the full range of brass instruments, from trumpet to tuba. In order to provide an unobstructed frontal view of the lips, the axis of the backbore has been rotated 90° from the axis of the rim, so that it emerges from the side of the cup. This is similar to the original design of Daniel W. Martin [J. Acoust. Soc. Am. 13, 305–308 (1942)]. Flat end windows are desirable for avoiding optical distortion, but they limit the range of viewing angles. Placement of the lips on the rim and the angle of the air channel between the lips can vary noticeably from performer to performer, so a flat window that works well for one embouchure may be quite inadequate for another. The large cup volumes of the low brass mouthpieces allow for greater flexibility in design without getting into severe distortion. A cylindrical end window with its axis parallel to that of the rotated backbore provides a wide range of viewing angles. A preliminary survey of embouchures used by beginning and advanced trombone players will be presented. [Work supported in part by the Scholarly and Creative Activities Committee at CSULB.]
The lateralization of simple dichotic pitches
Authors: Akeroyd Michael A. , Summerfield A. Quentin
Published: July 2002

A “simple” dichotic pitch arises when a single narrow band possesses a different interaural configuration from a surrounding broadband noise whose interaural configuration is uniform and correlated. Such pitches were created by interaurally decorrelating a narrow band (experiment 1) or by giving a narrow band a different interaural time difference from the noise (experiment 2). Using an adaptive forced-choice procedure, listeners adjusted the interaural intensity difference of “pointers” to match their lateralization to that of the dichotic pitches. The primary determinants of lateralization were the interaural configuration of the broadband noise (experiment 1), the center frequency of the narrow band (experiment 1), and its interaural configuration (experiment 2). The ability of two computational models to predict these results was evaluated. A version of the central-spectrum model [J. Raatgever and F. A. Bilsen, J. Acoust. Soc. Am. 80, 429–441 (1986)] incorporating realistic frequency selectivity accounted for the main results of experiment 1 but not experiment 2. A new “reconstruction–comparison” model accounted for the main results of both experiments. To accommodate the variables shown to influence lateralization, this model segregates evidence of the dichotic pitch from the noise, reconstructs the cross-correlogram of the noise, and compares it with the cross-correlogram of the original stimulus.
Measurement of the Axial Pressure Distribution of Molten Polymers in Flow Through a Circular Tube
Authors: Han C. D. , Charles M. , Philippoff W.
Published: July 2002

Axial pressure distributions for the flow of molten polyethylene and polystyrene has been obtained at shear rates of from 100 to 500 sec−1. In the case of polyethylene, fully developed flow was obtained within a length equivalent to one tube diameter (18 in.). The extrapolation of the polyethylene pressure profile revealed a normal stress (radial) at the exit which was greater than zero for all shear rates investigated. These extrapolated values of “exit pressure” were used to calculate values of the primary normal stress difference at the shear rates considered. The differences so calculated were found to correlate well with shear rate.
Rheological Implications of the Exit Pressure and Die Swell in Steady Capillary Flow of Polymer Melts. II. The Secondary Normal Stress Difference
Authors: Han C. D. , Charles M.
Published: July 2002

An equation relating the secondary normal stress difference to the “exit pressure” has been derived and used to calculate secondary normal stress difference for polyethylene and polypropylene melts. The results of these calculations indicate that the secondary normal stress difference for these fluids at shear rates of from 200 sec−1 to 800 sec−1 and at a temperature of 180°C is greater than the primary normal stress difference. This apparently unexpected result is discussed in terms of what is currently known regarding the behavior of polymer solutions.
Entrance- and Exit-Correction in Capillary Flow of Molten Polymers
Authors: Han C. D. , Charles M.
Published: July 2002

An apparatus is designed for the determination of the axial pressure distributions of molten polyethylene and polypropylene, both in a capillary and in a reservoir. Experimental results reveal that the pressure at the tube exit, termed “exit pressure,” is above atmospheric and it is found to be shear dependent for a given L/D ratio. The authors suggest a modified Bagley plot corrected for “exit pressure.” Such plots show curvature at the entrance region. The plots of entrance-correction vs. wall shear stress also show curvature, thus indicating that Hooke's law in shear is not obeyed by the polymers under study. The “exit pressure” is further used to correlate with the total pressure drop at the entry to the tube.
End Corrections in Capillary Flow of Polymer Melts with Nonzero Exit Pressures
Authors: McHugh T. W. , Harrell E. R. , Powell J. W. , Chartoff R. P.
Published: July 2002

Capillary flow data for a polypropylene melt exhibiting a positive exit pressure are analyzed using the normal Bagley correction procedure. The results obtained by this method are shown to be the same as those derived by the Hagenbach-Couette procedure. The agreement is exact because the Bagley procedure implicitly involves a linear extrapolation to zero exit pressure. Thus it is not necessary to subtract the exit pressure from total pressure drop as suggested by other workers. The Bagley procedure correctly adjusts data obtained for polymer melts in capillary flow experiments even if a positive exit pressure exists.
Flow of Viscoelastic Polymer Solutions Through an Abrupt 2-to-1 Expansion
Authors: Halmos Andrew L. , Boger David V.
Published: July 2002

Developing centerline velocity and reattachment lengths were measured for viscoelastic polymer solutions in an abrupt 2-to-1 expansion. Test fluids were characterized for shear stress and first normal stress difference using a Weissenberg Rheogoniometer. The deviation from inelastic behavior is examined for 0.31⩽n⩽0.58, 2.7⩽Re⩽116.0 and 0⩽We⩽0.195. No deviation from inelastic behavior was observed for We⩽0.047, while significant predevelopment of the flow field relative to inelastic behavior was observed for 0.047⩽We⩽0.114. A flow instability was observed for We⩾0.12. The conditions for unstable flow are compared to the reversed contraction flow and to criteria suggested in the literature.
Study of crystallite size and strain as a function of morphological evolution in zinc oxide powder obtained from hydroxycarbonate precursor
Authors: Sigoli Fernando Aparecido , de Oliveira Paiva-Santos Carlos , Jafelicci Miguel , Davolos Marian Rosaly
Published: July 2002

In this work, zinc oxide samples were obtained from hydroxycarbonate by thermal decomposition at 300 °C. Zinc hydroxycarbonate samples were produced by homogeneous precipitation over different periods of time. The method used to obtain zinc oxide produces different morphologies as a function of the precursor precipitation time. Among the obtained particle shapes were porous spherical aggregates, spherulitic needle aggregates, and single acicular particles. This work investigated spherulitic needle-aggregate formation and the correlation among morphology, domain size, and microstrain. Transmission electron microscopy data revealed that the acicular particles that form the spherulitic needle aggregates consist of nanometer crystallites. Apparent crystallite size and microstrain in the directions perpendicular to (h00), (h0l), (hk0), and (00l) planes were invariable as a function of precursor precipitation time. From the results, it was possible to conclude that the precursor precipitation period directly influenced the morphology of the zinc oxide but did not influence average crystallite size and microstrain for ZnO samples. Therefore, using this route, it was possible to prepare zinc oxide with different morphologies without microstructural alterations.
A novel CSoDoA based passive islanding detection technique for multi‐DER AC microgrid control
Authors: Bodda Sivaramarao , Agnihotri Prashant , Biswas Santosh
Published: January 2023

Micro‐grid islanding methods are gaining importance as the presence of renewable energy resources is becoming increasingly popular in power distribution. Among all the islanding methods, passive methods are easy to implement and applicable to all types of DERs provided the NDZ is minimized. This article presents a novel passive islanding detection method based on the CSoDoA of ellipse formed by the successive phase voltages to address the NDZ problem. The peak magnitude and phase angle difference of voltages are the parameters to be estimated to compute the area of the ellipse. State‐of‐the‐art passive methods consider the effect of either magnitude or phase angle or frequency as an islanding detection metric. The CSoDoA metric combines the effect of both magnitude and phase angle thereby reducing the NDZ. The proposed method is validated on both synchronous and inverter‐interfaced DERs. The test systems considered are both single‐DER based MG and modified IEEE 13 bus multi‐DER MG. The CSoDoA algorithm is implemented on a Raspberry‐Pi controller and validated using HIL workbench with real‐time simulator OP‐4510. Various islanding and non‐islanding events are simulated, tested and it is evident from the results that it has a very small NDZ.
Controlling an automatic voltage regulator using a novel Harris hawks and simulated annealing optimization technique
Authors: Izci Davut , Ekinci Serdar , Zeynelgil Hatice Lale
Published: January 2023

Maintaining the terminal voltage of a power system is a crucial process and this can be achieved via a system named automatic voltage regulator (AVR). However, an AVR needs an appropriate control method. In this context, this article proposes a novel Harris hawks optimization (HHO) and simulated annealing (SA) technique which can be used for AVR. The proposed optimization technique (HHO‐SA) combines the good exploration feature of HHO with the exceptional local search feature of SA. The HHO‐SA algorithm is introduced as a novel design method to obtain the optimum parameters for proportional + integral + derivative plus second order derivative (PID + DD) controller adopted in the AVR. Time domain objective function of the system is effectively minimized and the best PID + DD parameters are obtained. The analysis of statistical tests, convergence, transient and frequency responses, root locus, and disturbance rejection along with robustness are conducted for verifying the efficiency of the HHO‐SA algorithm. Also, the performance of the HHO‐SA tuned PID + DD controller on AVR is compared with the original HHO tuned PID + DD along with PID, FOPID, and PID + DD controllers that are adjusted by state‐of‐the‐art metaheuristic methods. The practical implementation of the proposed controller is also demonstrated in this work. The extensive simulation results and comparisons with the existing controllers adopting the same set of data demonstrate the superior control performance and good robustness of the HHO‐SA tuned PID + DD controller.
Polymer‐Supported Phosphoric‐Acid Catalysed Enantioselective Pictet‐Spengler Cyclisation for the Synthesis of Quaternary Tryptolines in Batch/Continuous Flow
Authors: Chaudhari Moreshwar B. , Gupta Prachi , Llanes Patricia , Pericàs Miquel A.
Published: January 2023

The enantioselective Pictet‐Spenlger reaction of tryptamines and diketo compounds catalyzed by a polymer‐supported phosphoric acid (TRIP) has been accomplished for the first time in continuous flow. Using this approach, a diverse library of quaternary tryptolines has been synthesized in 36–95% yield with 39–99% enantiomeric excess. The scalability of the reaction has been demonstrated in continuous flow, with a residence time of only 24 minutes. The robust immobilized catalyst has been recycled and reused multiple times in batch and flow. The synthesis of the chiral precursors of Tadalafil, the Iboga‐type alkaloid (+)‐Tabertinggine and antimalarial spiroindolinones has been achieved in batch and continuous‐flow.

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Selective Catalytic Cross‐Cyclotrimerization En Route to 1,4‐Diborylated Benzenes and Their Synthetic Transformations
Authors: Fadeev Alexander A. , Manca Gabriele , Kotora Martin
Published: January 2023

A synthesis of 1,4‐diborylated benzenes was achieved by the Ru‐catalyzed regioselective co‐cyclotrimerization of alkynes with a commercially available ethynyl boronate. The reaction is applicable to a wide array of alkynes with metal‐coordinating groups, providing synthetically useful diborylated benzenes in 23–68% isolated yields. DFT calculations shed light on the reaction course and the origin of its remarkable regioselectivity. Selected diborylated benzenes were converted into various products, such as quinones and hydroquinones, including three natural bioactive small molecules.

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Mimicking the Biological Sense of Taste In Vitro Using a Taste Organoids‐on‐a‐Chip System
Authors: Wu Jianguo , Chen Changming , Qin Chunlian , Li Yihong , Jiang Nan , Yuan Qunchen , Duan Yan , Liu Mengxue , Wei Xinwei , Yu Yiqun , Zhuang Liujing , Wang Ping
Published: January 2023

Thanks to the gustatory system, humans can experience the flavors in foods and drinks while avoiding the intake of some harmful substances. Although great advances in the fields of biotechnology, microfluidics, and nanotechnologies have been made in recent years, this astonishing recognition system can hardly be replaced by any artificial sensors designed so far. Here, taste organoids are coupled with an extracellular potential sensor array to form a novel bioelectronic organoid and developed a taste organoids‐on‐a‐chip system (TOS) for highly mimicking the biological sense of taste ex vivo with high stability and repeatability. The taste organoids maintain key taste receptors expression after the third passage and high cell viability during 7 days of on‐chip culture. Most importantly, the TOS not only distinguishs sour, sweet, bitter, and salt stimuli with great specificity, but also recognizes varying concentrations of the stimuli through an analytical method based on the extraction of signal features and principal component analysis. It is hoped that this bioelectronic tongue can facilitate studies in food quality controls, disease modelling, and drug screening.
Aniline Sulfonic Acid Induced Uniform Perovskite Film for Large‐Scale Photovoltaics
Authors: Wang Kai‐li , Li Meng , Lou Yan‐Hui , Chen Jing , Shi Yi‐Ran , Chen Chun‐Hao , Zhou Yu‐Hang , Wang Zhao‐Kui , Liao Liang‐Sheng
Published: January 2023

Unreacted/excess lead iodide is considered to be the archcriminal for the rapid degradation of hybrid perovskite solar cells. Meanwhile, a high‐quality perovskite film with uniform and large grain size is the basis for high‐performance perovskite modules. Herein, a dual‐site molecular additive 4‐Aniline Sulfonic Acid (4A) is developed to regulate the unreacted/excess PbI2 and passivate defects through hydrogen bonding and intermolecular interactions between amino, and a sulfate groups and PbI2, respectively. Furthermore, the introduction of the 4A additive can induce perovskite seeds to grow uniformly on the substrate, yielding dense, uniform and defect‐less perovskite films with large grain sizes. This enables the fabrication of perovskite photovoltaics with a maximum power conversion efficiency of 24.09% (0.09 cm2) and 20.87% (16 cm2), respectively. This work demonstrated a new strategy to deposit high‐quality large‐scale perovskite films for photovoltaic modules.
Metastable Decomposition Realizing Dendrite‐Free Solid‐State Li Metal Batteries
Authors: Song Ruifeng , Yao Jingming , Xu Ruonan , Li Zhixuan , Yan Xinlin , Yu Chuang , Huang Zhigao , Zhang Long
Published: January 2023

A stable interface and preventing dendrite‐growth are two crucial factors to realize long‐life all‐solid‐state Li batteries (ASSLBs) using sulfide‐based solid electrolytes (SEs) and Li metal anodes. But it remains a challenge to accomplish the two factors simultaneously. Here, an effective strategy is reported to realize this goal in Li‐argyrodites via self‐engineered metastable decomposition that is enabled by Si doping in Cl‐rich argyrodites. It is shown that Cl atoms in the lattice become metastable and are highly reactive with Li atoms. The locally deposited/grown Li crystal nuclei are thus depleted by the metastable Cl during electrochemical cycling, in situ generating electrically insulated LiCl shells concentrated at the argyrodite grain boundaries. The shells in turn prevent the autochthonous Li redeposition and act as self‐protective layers to restrain the continuous decomposition in the interior argyrodite, that is, self‐assembly of reactive‐cores‐stable‐shells to Li metal, thereby enabling an ultra‐long life ASSLB using Li metal anodes at room temperature under relatively high current densities.