bluuebunny/crossref_metadata_2025 huggingface dataset:
Patterns of spectra and timbre in musical context
Authors: Kendall Roger A.
Published: July 2002

Although there are a few exceptions, much of the research on musical timbre has involved single notes drawn from the center of the tessituras of the instruments employed. In single-tone research, multiple authors have found that the long-time-average spectral centroid maps well with the primary dimension of multidimensional perceptual spaces (ca. r>0.89). The second dimension of perceptual spaces often maps to a measure of spectral flux or variability. The present study examines the patterning of spectral centroid and flux in quasi-musical contexts. Bb major scales consisting of quarter notes followed by quarter rests (M.M.=72) were recorded across the playing range of a variety of orchestral winds and strings. In addition, a folk song in Bb major was performed in normal tessitura for a given instrument. Spectral analyses (ninth-order FFT) were conducted for every steady state, and the unweighted spectral centroid, independent of frequency, calculated. Various statistical and mathematical analyses were performed, including the construction of a theoretical multidimensional map that incorporates pitch class. Perceptual analyses were conducted using verbal ratings of timbral similarity and quality. Results suggest that patternings of spectra are well connected to the fingerings employed, and hence driver-resonator characteristics.
Investigations of a thermoacoustic refrigerator prototype
Authors: Minner Brian , Mongeau Luc , Braun Jim
Published: July 2002

A thermoacoustic refrigerator prototype was built and tested. The system was designed to provide 140-W cooling power with a temperature lift of 40°F, using a 55% mix of helium–argon at 20 bars pressure and operating at 180 Hz. Leaf springs were used to tune the mechanical driver system to be resonant at 154 Hz, such that the sum of mechanical and acoustical reactances is zero near 180 Hz. Initial testing achieved acoustic powers near 50 W, with an electroacoustic transduction efficiency of about 27% (the maximum efficiency is near 45%). Pressure amplitudes were near 3% of the mean in the stack region, and heat rejected to a secondary fluid was measured to be near 60 W. While this acoustic power level is near the target for the desired cooling load, initial tests indicate that the cooling power is well below 140 W. Results of continuing testing and investigations for determination of the cause of discrepancies in pressures, temperatures, and cooling power between measurement and model (Deltae) will be presented. The influence of DC flows, nuisance heat loads, gas mixture, and hardware (stack and heat exchanger) factors will be addressed. Accelerometer, thermocouple, and pressure sensor data will be presented and interpreted.
Intensity-difference limens as a function of level for brief 2-kHz Gaussian-shaped tones
Authors: Nizami Lance , Jesteadt Walt , Reimer Jason F.
Published: July 2002

Intensity-difference limens (DLs) were measured for brief 2-kHz tones whose frequency spectra contained no sidelobes to 90 dB below the peak. The tone’s pedestal levels spanned 30–90 dB SPL in 10-dB steps, where tone level was the SPL of the carrier. Tone duration was set by terminating the Gaussian envelope at 4 standard deviations from the mean. The DLs were obtained using Levitt’s method for two men and three women (ages 18–40) having normal auditory thresholds. The tone durations, 32, 8, and 4 ms, were all integer multiples of the carrier’s period. For the 32-ms tones, plotting DL vs pedestal level revealed the ‘‘near-miss to Weber’s law’’ known for longer tones, although present DLs were higher. The DLs for 8 and 4 ms rose from about 2 dB at 30 dB SPL to 6–8 dB at 50–70 dB SPL, dropping to 1–2 dB at 90 dB SPL. (DLs will also be shown for 2 and 16 ms for three of the listeners.) A nonmonotonic DL also occurs for the acoustic click [Raab and Taub, J. Acoust. Soc. Am. 46, 965–968 (1969)], which is surprising as the click’s frequency spectrum is much broader than that of the Gaussian-shaped tone.
Binaural coherence edge pitch—Manipulations and models
Authors: Hartmann William M. , McMillon Colleen D. , Rakerd Brad
Published: July 2002

Binaural coherence edge pitch (BICEP) is a dichotic broadband noise pitch effect. The stimulus is made by summing spectrally dense sine components with random phases. The interaural phase angle is a constant (e.g., 0 or π) for components with frequencies below (or above) a chosen edge frequency, and it is a random variable for the remaining components. Pitch-matching experiments show that the BICEP exists for coherence edge frequencies between 300 and 1000 Hz. It is matched by a pure tone frequency shifted from the edge frequency by 5% to 10%. The matching frequency falls on the incoherent side of the edge. The BICEP persists if the noise to one of the ears is delayed (<3 ms). Some BICEP exists even when the component amplitudes are entirely independent in the two ears, so long as the phase coherence conditions of the stimulus are maintained. The existence of the BICEP is a challenge for current models of dichotic pitch, though the pitch shift is consistent with the equalization-cancellation model as previously applied to dichotic pitch effects by M. A. Klein and W. M. Hartmann [J. Acoust. Soc. Am. 70, 51–61 (1981)]. [Work supported by the NIDCD of the NIH and by the NSF REU Program.]
Frequency analysis of broadband acoustic signals propagating through nonlinear internal waves
Authors: Frank Scott , Siegmann William L. , Badiey Mohsen , Mu Yongke , Lynch James F. , Wolf Stephen
Published: July 2002

Nonlinear internal waves along the ocean thermocline are known to affect modal compositions and other properties of acoustic signals. Such nonlinear waves were observed during the SWARM 95 Orthogonal Propagation Experiment, where extensive data were collected from two broadband sources. One source was a 30-s linear frequency modulated sweep signal, and the other was a 0.1-s airgun shot. Both sources were repeated every minute and received by two vertical linear arrays several kilometers away. Sound speed profiles were measured near the source and the receiver arrays simultaneously. The influences of internal waves on the broadband frequency behavior of received and simulated signals are described. Features of energy spectral density and of transmission loss versus frequency plots are used to detect resonant frequencies where anomalous loss occurs. A time-frequency analysis of received signals at several ranges is performed to determine modal propagation characteristics, including modal transitions of the signals passing through the internal waves. An objective of this study is to link acoustic signal behavior to internal wave properties such as wavelength, packet length, and amplitude. [Work supported by ONR.]
Temporal coherence of matched-field, matched-mode, and matched-beam correlation as a function of frequency and range in the Sicily Strait
Authors: Yang T. C. , Siderius Martin , Yoo Kwang
Published: July 2002

Ocean medium fluctuations reduce the temporal coherence of acoustic signals. Temporal coherence limits the time duration a replica field can be used for matched-field, matched-mode, and matched-beam source localization in a random ocean. During the Advent 99 experiment, which took place in the Sicily Strait in May 1999, narrow-band signals (12 tones in the band 200–1500 Hz) were transmitted from a bottom-mounted tower and received on a 64-phone line array covering the water column; the water depth was 80 m. The data were collected at three ranges: 2, 5, and 10 km. Using a reference signal as the replica, temporal coherence was measured for the vertical array in the phone domain (matched-field correlation), mode domain (matched-mode correlation), and in the beam domain (matched-beam correlation). For the latter two cases, coherence is a function of the modes and beams used. This paper presents the preliminary results of the data analysis and comparison with acoustic simulations based on an internal wave model. Implications for signal processing will be discussed. [Work was supported by ONR and SACLANTCEN.]
The evasive responses of praying mantids and tiger beetles to complex ultrasonic pulse trains produced by echolocating bats
Authors: Yager David D.
Published: July 2002

Two highly visual diurnal insect predators, praying mantids and tiger beetles, become the prey of echolocating bats at night. Although very distant phylogenetically, the two insects have evolved similar ultrasound-triggered behavioral responses to help them evade capture. The tiger beetle ears have a conventional tympanate design with sharp tuning at 30–35 kHz and directional capabilities. The mantis peripheral auditory system is highly unconventional with a single cyclopean ear in the metathorax that apparently sacrifices directionality for increased sensitivity. There are six to eight pairs of ascending auditory interneurons in the mantis thorax. Even though it slows response time, auditory processing in the brain is required for the evasive behavior, i.e., it is not a simple reflex. The tiger beetles behavioral response to ultrasound is similar, but there appears to be no system of large ascending interneurons. In both insects, the nocturnal ultrasound-triggered evasive behaviors probably evolved from diurnal defensive displays triggered by visual stimuli. Thus, the evolutionary innovation may not have been extensive new circuitry, but, rather, a context-dependent switch that links the behavior to vision during the day and to hearing at night.
The impact of high-dose lithotripsy on renal structure and function
Authors: Willis Lynn R. , Evan Andrew P. , Connors Bret A. , Blomgren Philip , Lingeman James E.
Published: July 2002

These studies characterized the effects of normal and high ‘‘doses’’ of shock waves on renal structure and function in healthy and compromised kidneys of young, anesthetized pigs. A ‘‘normal’’ dose of 2000 shock waves (24 kV, unmodified HM3 lithotripter) to one kidney produced lesions comprising about 8% of functional renal mass, transiently reduced renal blood flow and glomerular filtration rate (GFR) in both kidneys, and reduced regional perfusion in shocked kidneys. High doses of shock waves to one kidney (8000 shocks at 24 kV) produced larger lesions (about 14%), intensified the initial vasoconstriction in both kidneys, and sustained the reduction of GFR in the shocked kidneys for at least 24 h after treatment. The administration of 2000 shock waves (24 kV) to pyelonephritic (compromised) kidneys exaggerated the structural/functional impairment by inducing large lesions and intense vasoconstriction normally seen only after 8000 shock waves in healthy kidneys. We conclude that both shock wave number and preexisting renal disease increase the severity of tissue injury and functional impairment produced by shock wave lithotripsy. Since renal ischemia and inflammation occur in association with such injury, subsequent renal scarring and permanent loss of functional renal mass may also be related to shock wave dosage.
Characterization of a cosine-shaped horn
Authors: Arenas Jorge , Crocker Malcolm
Published: July 2002

Several approaches to the problem of the acoustic wave propagation in a duct with a varying cross section have been described in the literature. It has been shown that a simple one-dimensional analysis gives accurate predictions of the sound propagation. In this research, the impedance of a cosine-shaped horn is obtained using the Wentzel–Kramers–Brillouin (WKB) approximation to solve the Webster wave equation and the results are compared with those obtained from a numerical solution of the equivalent system of nonlinear equations. A comparison of the throat impedance ratio is presented for similar exponential, conical, parabolic, and catenoidal horns with the same overall dimensions. The mouth of the horn is assumed to be terminated in an infinite baffle. In addition, since the device may be used as an impedance transformer, the results for the impedance ratio for two pipes of different areas joined by a cosine-shaped connector are compared with several well-known couplings. Such a cosine-shaped connector will act as a simple discontinuity when its length is short compared with a wavelength and as a transformer for acoustic impedance for higher frequencies.
Anatomy of a readable publication
Authors: Burgess John C.
Published: July 2002

Richard Borden, some time ago, came up with a four-point formula that applies to any type of communication. The colloquial expressing of this formula consists of the phrases (1) Ho hum! (2) Why bring that up? (3) For instance! (4) So what? The present paper rephrases this formula so that it can be used by authors of research articles for JASA. The phrase ‘‘Ho hum,’’ for example, translates to the requirement that the opening paragraph of an article should attract the reader’s interest and motivate the reader to continue reading. Examples are taken from various JASA papers that indicate that those papers which are manifestly readable are in actuality (even if unconsciously) adhering to Borden’s formula. It is suggested that authors who want their papers to be read and understood give serious consideration to making use of Borden’s formula.
The use of color in representing complex number data
Authors: Weinreich Gabriel
Published: July 2002

With the general availability of color printers, the application of color for representing physical quantities has taken on a new interest. Since hue is by its nature a cyclic variable, it is ideally suited for representing the phase of a complex number; at the same time, color saturation can be used to specify amplitude. In this way, a complex number is conveniently represented by a single color; and a complex number that depends on, say, frequency, such as the input admittance of a wind instrument or the radiativity of a violin, can be mapped into a one-dimensional colored band. The great advantage of such a method is that these one-dimensional bands can be ‘‘stacked’’ in a perpendicular direction to indicate how the whole function behaves when another independent variable is introduced; for example, one might exhibit a radiativity as a function of both frequency and direction, or an input impedance as a function of both frequency and the number of open tone holes. A detailed application of the method to the ‘‘Swiss Cheese Violin’’ of Carleen Hutchins will be presented. [Work supported by NSF.]
Nonlinear wave interactions in water with bubbles: Solved and unsolved problems
Authors: Ostrovsky Lev A.
Published: July 2002

This lecture is an outline of some nontrivial aspects of nonlinear acoustics of bubbly liquids. It is common knowledge now that a very small volume content of bubbles can increase the nonlinearity parameter of the gas–liquid mixture by several orders. Basic problems of nonlinear wave propagation in such media with shock wave formation, harmonic generation, etc., have been thoroughly discussed during the last decades, especially for a less realistic case of equal-size bubbles. Not as well understood are waves in bubbles widely distributed in sizes, especially nonlinear scattering problems when the standard ‘‘continual’’ approximation is inapplicable. Also, collective behavior of bubbles interacting with each other (not just via the macroscopic acoustic field) can radically change the nonlinear properties on a medium. Here, some relevant theoretical and experimental results are discussed, including nonlinear scattering of sound on sea bubbles; the use of resonance bubble layers to enhance nonlinear transformation; and some effects of bubble interaction due to period-averaged forces such as radiation pressure. The relationship between coherent and incoherent parts of acoustic field and some ideas of an ‘‘acoustic masker’’ are also discussed
Numerical results for acoustic scattering from a coated wedge
Authors: Hughes R. , Niemiec J. , Solomon S. , Überall Herbert
Published: July 2002

Earlier work on the acoustic wedge problem mainly dealt with an impenetrable wedge, including the work of Sommerfeld (1896), Bromwrich (1915), Carslaw (1920), and Oberhettinger (1954, 1958). The present investigation assumes a line source parallel to the edge of the wedge, and extends Oberhettinger’s approach for the scattering of a sound wave from the edge of a perfectly reflecting wedge, to the case that the field does not satisfy a Dirichlet or Neumann boundary condition on the wedge surface, but an impedance boundary condition. Such a condition is capable of describing the effect of a lossy coating on the wedge surface as shown for the electromagnetic case (Überall, 1964, 1966), and the corresponding impedance for the acoustic case has been obtained here for one, two, and multiple layers of coating. Numerical results for the wedge-scattered sound intensity will be presented and discussed.
Spatial unmasking for nearby speech sources in a simulated anechoic environment
Authors: Schickler Jason , Kopčo Norbert , Shinn-Cunningham Barbara G. , Litovsky Ruth Y.
Published: July 2002

The ‘‘cocktail party effect’’ is traditionally studied with sources varying in azimuth, where binaural and level cues are large. In these conditions, speech intelligibility improves dramatically when the target speech and maskers are spatially separated. In the present study, we investigated spatial unmasking of nearby sources for several configurations of target and sources varying in distance and azimuth. Targets were sentences from the IEEE corpus and maskers were speech-shaped noise. Locations were simulated over headphones using anechoic head-related transfer functions (both individually measured and using a spherical-head model). Speech reception thresholds were measured adaptively, varying target level while keeping masker level constant. For nearby sources, overall energy effects (due to changes in target and masker level with distance) are large. Therefore, target level was normalized to equate the signal-to-noise ratio at the better ear in all conditions. This approach allowed direct measurement of binaural unmasking in the various conditions. Overall energy effects (removed by the normalization) are also reported. Results are compared with detection threshold measurements from similar experiments. [Work supported in part by AFOSR Grant F49620-98-1-0108 to BGSC and NIDCD Grant DC02696 to RYL.]
Investigations of the precedence effect with narrow-band continuous noise
Authors: Dizon Roberto , Colburn H. Steven
Published: July 2002

The precedence effect has been shown to be strong for stimuli with onset transients, e.g., clicks. Zurek [J. Acoust. Soc. Am. 67, 952–964 (1980)] showed that a continuous, broadband noise whose fine structure leads that of a simulated reflection dominates lateralization even when onset gating cues have been removed. We report on experiments similar to those of Zurek, but using narrow-band noises of varying bandwidths and center frequencies. In a 2IFC headphone task, the leading and lagging stimuli are placed on either side of midline (±300-μs ITD) in the first interval, and the signals to the two ears are switched in the second interval. Subjects report whether the stimulus in the second interval is to the right or left of the first. Results are consistent with a precedence effect for bandwidths as narrow as a critical band. For narrower bandwidths, onset dominance is still observed, but with oscillations in lateralization consistent with the interaural differences expected for narrow-band stimuli, given the ITDs of the lead and lag stimuli and the lead–lag delay. As bandwidths approach zero, lateralization is dominated by these interaural differences, and onset dominance is not evident. [Work supported by NIH (DC00100) and ONR-MURI (Z883401).]
Influence of visual cues on the perception of surround sound
Authors: Czyzewski Andrzej , Kornacki Artur , Kostek Bozena , Odya Piotr , Zielinski Slawomir
Published: July 2002

Contemporary digital video, film, or multimedia presentations are often accompanied by the surround sound. Techniques and standards involved in digital video processing are much more developed than concepts underlying creating recording and mixing of the multichannel sound. The main challenge in the sound processing in the multichannel system is to create an appropriate basis for connecting multimodal context of visual and sound domains. Therefore one of the purposes of experiments is to study in which way and how the surround sound interferes or is associated with the visual context. This kind of study was hitherto carried out when two-channel sound technique was associated with a stereo TV. However, there are not many studies done yet that associate surround sound and digital video presented at the TV screen. The main issue in such experiments is the analysis of the influence of visual cues on perception of the surround sound. This problem will be addressed in the paper.
Active stabilization of liquid capillary bridges using optically sensed modal amplitudes
Authors: Thiessen David B. , Marr-Lyon Mark J. , Marston Philip L.
Published: July 2002

Cylindrical capillary bridges consisting of liquid between two circular supports naturally become unstable and break when the length of the bridge exceeds its circumference for the situation where the weight or buoyancy of the bridge can be neglected. This is the Rayleigh–Plateau (RP) slenderness limit which is relevant to the management of liquids and to the formation of liquid drops. We have demonstrated methods of suppressing this instability based on the optical sensing of the instantaneous modal amplitude and the rapid adjustment of the axial distribution of applied radial stress. This applied stress may be the result of ultrasonic radiation pressure [M. J. Marr-Lyon et al., J. Fluid Mech. 351, 345–357 (1997)] or electrostatic stresses from an array of electrodes [M. J. Marr-Lyon et al., Phys. Fluids (accepted)]. We have stabilized bridges as much as 42% beyond the RP limit by phasing the stress so that the effective modal spring constant becomes positive; however, the modal damping is then decreased. The closed-loop response includes terms associated with boundary-layer damping and the sensor’s response time. The analysis indicates that damping of short bridges may be enhanced by reversing the feedback phase. [Work supported by NASA.]
Active structural intensity control using strain sensing
Authors: Audrain Pascal , Masson Patrice , Berry Alain
Published: July 2002

An investigation of structural intensity control using strain sensing is presented in this paper. As opposed to previous work, the approach taken here does not assume waves propagating predominantly in one direction. Moreover, the instantaneous intensity is completely taken into account in the control algorithm, i.e., all the terms are considered in the real-time control process and, in particular, the evanescent waves are considered in this approach. A finite-difference approach using discrete PVDF strain sensors is used as the sensing scheme. A feedforward filtered-X LMS algorithm is adapted to this energy-based control problem, involving a nonpositive definite quadratic form in general. In this respect, the approach is limited to cases where the geometry is such that the intensity component will have the same sign for the control source and the primary disturbance. Experimental validation of the approach is conducted on a free–free beam covered with viscoelastic material. A comparison is made between classical acceleration control and structural intensity control and the performance of both approaches is presented. These results tend to indicate that using intensity control allows the error sensors to be placed closer to the control source and the primary disturbance, while preserving a good control performance.
Active/passive design for vibration control
Authors: Rule John A. , Clark Robert L.
Published: July 2002

A method has been developed for the control of panel vibration using a hybrid active/passive spatial optimization technique. The method relies on the rapid estimation of Hankel singular values (HSV’s) to predict coupling of sensor/actuator pairs to particular vibration modes of interest. The two-step process first requires the selection of the best sensor/actuator pair for active control, using a design metric which is typically used to target the control of low-frequency, long-wavelength modes, while simultaneously minimizing higher frequency, or out-of-bandwidth, system response. With the active control system in place, potentially destabilizing out-of-bandwidth modes are identified for passive control. A similar design metric is then applied which emphasizes coupling of passive damping material to the high-frequency, short-wavelength structural modes. Numerical simulations were performed to demonstrate this concept. It was then implemented on an 18-×16-in steel plate. Plate response was measured first for the uncontrolled plate, then the plate with just the active control system in place, and finally the complete hybrid active/passive system. Performance of each system was analyzed, with benefits and tradeoffs considered.
Assessing the relative detection performance of matched-field processing and conventional beamforming
Authors: Maranda Brian H. , Thomson David J.
Published: July 2002

The primary advantage of matched-field processing (MFP) over conventional plane-wave beamforming is the ability to localize an acoustic source in a single data snapshot; for example, MFP can help to decide whether or not the source is submerged. It is to be expected that MFP will also provide improved detection performance over the plane-wave beamformer when the acoustic pressure field at the array exhibits the complicated behavior that is typically observed in the oceanic waveguide. Accurately quantifying the performance gain is difficult, owing to analytical problems in determining the exact performance of a detector that thresholds many correlated search cells. However, on the basis of simple statistical arguments concerning the effective dimensionality of the search spaces, it is claimed that a rough comparison of detector performance is provided by the ratio of the quadratic forms that are used as the decision variables. This ratio is computed for several array and ocean scenarios, including both a vertical line array in shallow water and a horizontal line array in deep water. Two-dimensional plots (depth and range) are used to illustrate the detection gain that can be provided by matched-field processing.
Performance analysis for a short vertical array in a shallow-water waveguide
Authors: Gao Tainfu , Wang Lan , Shang E. C.
Published: July 2002

Vertical line array (VLA) has been widely used for field data collection in underwater acoustics. The performance of VLA strongly depends on: (1) the signal processing approach used, (2) the environmental knowledge, (3) the signal-to-noise ratio (S/N), and (4) the configuration of the array (length, position, curvature). In this paper, we concentrate our investigation on the length effect. Theoretical analysis has been done for a short array in a Pekeris shallow-water waveguide. For lower frequency in shallow water, the information provided by a VLA can be described by the capability of mode decomposition, which is determined by the spectrum of the eigenvalue of the ‘‘covariance matrix’’ of the field sampled by the VLA. The approximate decay behavior of the spectrum is calculated analytically for short array. It is shown that the estimated eigenvalues are very close to the exact eigenvalues. The indicator of the performance used in this paper is the number of ‘‘S,’’ which represents the dimension of the ‘‘signal space,’’ and can be easily determined by the spectrum decay law.
Detection of impulsive signals in shallow water
Authors: Cable Peter G.
Published: July 2002

The effect of multipath induced time spread on the detectability of impulsive signals transmitted in shallow water is considered. The effective signal duration and temporal shape of received signal energy, two related features of the pulse spread associated with propagation, were analyzed for the shallow-water coastal environments in the DARPA Area Characterization Tests (ACT I, II, and III). Measured multipath induced time spreads were between 30 and 40 ms and, for each environment, the integrated received energy was found to be well fitted by an exponential function of the integration time. Using the observed signal energy durations and shapes, a model of energy detection of impulsive signals in shallow water was formulated and will be described. An analysis of expected performance (probability of signal detection for fixed probability of false alarm) as a function of input signal-to-background energy ratio and integration time will be presented.
First-order bias and second-order variance of maximum likelihood time delay and Doppler shift estimates
Authors: Naftali Eran , Makris Nicholas C.
Published: July 2002

Exact expressions for the bias and variance of a maximum likelihood time delay and Doppler shift estimate are difficult to obtain analytically. It has become popular in such nonlinear problems to compute limiting bounds on mean-square estimation error, such as the Cramer–Rao bound (CRB), since these are easier to obtain than the true variance. Recently it has been shown [Makris and Naftali, J. Acoust. Soc. Am. 106, 2 (1999)] that the first-order bias and second-order variance of a general maximum-likelihood estimator (MLE) can be computed analytically, using higher-order asymptotics. This approach is applied to the classic radar/sonar problem of estimating the time delay and Doppler shift of a deterministic signal in additive white Gaussian noise. The MLE is shown to be unbiased to first order for this problem. By evaluating the asymptotic expansion for the variance for three specific signal waveforms, Gaussian, LFM, and HFM, it is found that (a) the CRB yields an unrealistically optimistic variance estimate for SNR’s lower than 20–30 dB, (b) both first- and second-order time-delay variance terms decrease with increasing signal bandwidth, and (c) both first and second Doppler-shift variance terms of LFM and HFM signals approach constant values as bandwidth increases.
Eliminating acoustical barriers to learning in classrooms—Case study of reverberation reduction in elementary school gymnasiums
Authors: Brooks Bennett M.
Published: July 2002

A gymnasium can be a highly reverberant space. This is a consequence of the large room volume coupled with an abundance of hard surfaces. School designers frequently overlook the need for reverberation control in gymnasiums, cafeterias, and other large school rooms. The high level of reverberation promotes a high noise level and interferes with speech intelligibility, degrading the primary functions of those spaces. Moreover, those rooms are often used for additional functions, such as student assemblies, community meetings, and school performances, which will also suffer from excess reverberation. A case study is presented for two elementary school gymnasiums, each with mid-frequency reverberation times of about 5 s. Renovation treatments to control reverberation were developed using simple computer models. Significant reductions in reverberation and noise level were achieved. As a result, student manageability was improved, and teacher sanity was restored.
A method for fast inversion of ocean waveguide parameters
Authors: Jiang Dejun
Published: July 2002

A method for fast inversion of waveguide parameters using a broadband pulse signal is presented. The input parameters are relative amplitudes and relative delays of normal modes which can be determined with TDE technique. The cost function consists of the sum of two parts; one is the relative amplitudes of normal modes which can be used to calculate the velocity and density of waveguide, the other is the relative delays of normal modes which can be used to calculate the attenuation coefficient. A genetic algorithm (GA) is used to estimate waveguide parameters. The result shows that the method not only increased the inversion speed significantly, but is also robust to ocean environment.
Hot topics in psychological and physiological acoustics: Compression
Authors: Bacon Sid P.
Published: July 2002

The auditory system has an extraordinarily large dynamic range, evidenced, for example, by the fact that humans can detect an approximately 1-dB increment in the level of sounds that vary over a range of 120 dB. This enormous dynamic range is a consequence of the compression that is observed in the vibratory response of the basilar membrane in the cochlea. Damage to the cochlea, which occurs in many types of hearing loss, usually results in a reduction or loss of compression and, importantly, a reduction in the dynamic range of hearing. Physiological evidence for compression will be presented, along with results from recent psychophysical experiments that provide quantitative estimates of the degree of compression in humans. In addition, the effects of temporary and permanent hearing loss will be described, as will some of the signal processing strategies that are employed by many hearing aids in an effort to compensate for reduced compression.
Thermoacoustic microengines
Authors: Yaron Ran , Radebaugh Ray , Elias Ezra , Ostrovsky Lev A.
Published: July 2002

The high rate of heat transfer (up to 500 MW/m2) which can be achieved by explosive bubbles has long been recognized. This process finds a widening range of application from microsurgery to computer peripherals design. The best-known example is the thermal ink-jet printer, where an ultrahigh heat flux applied for short duration of about 6 μs induces rapid bubble generation and growth, which drives an adequate mass of ink forward through the exit nozzle. Explosive boiling is a phenomenon in which boiling is developed in an explosive manner at large superheat. Superheat conditions can be realized by absorption of a strong laser beam or by quick heating of a surface. Reversible phase transitions near the fluid’s critical temperature by ‘‘acoustic explosive bubble’’ may provide a new way to continuously transfer the high thermal power associated with explosive boiling in a variety of heat exchange processes. For example, explosive bubbles could form the basis for fluid micropumping devices to be used in microrefrigerators. The present paper concentrates mainly on estimating the necessary conditions for realizing explosive boiling in liquids and how this boiling can be used to create a stable acoustic oscillation involving growth and collapse of the bubble.
Integrated photoelectric device made of a piezoelectric ceramic exhibiting pyroelectricity and an internal photoeffect
Authors: Quanlu Li
Published: July 2002

This paper reports on the preparation of a piezoelectric ceramic, which also exhibits pyroelectricity and an internal photoeffect. It then describes the design and trial production of a new integrated photoelectric device using this ceramic with a piezoelectric transformer, a solar cell, and an inverter. Important applications of this device are given.
Transient Normal Force Transducer Response in a Modified Weissenberg Rheogoniometer
Authors: Hansen M. G. , Nazem F.
Published: July 2002

A theoretical and experimental study for measuring meaningful transient normal force in the cone-and-plate geometry of the Weissenberg rheogoniometer type apparatus is presented. Meissner's modifications (J. Appl. Polym. Sci., 16, 2877 (1972)) are adapted to our Weissenberg rheogoniometer. The apparatus is stiffened and the closed loop feedback system is replaced by an open loop cantilever spring to extend the capability of the Weissenberg rheogoniometer to ascertain the transient normal force measurement. Due to these modifications, the transient gap variation in the instrument is limited to less than 1 μ which causes negligible effect on the normal stress measurement response. However, depending on the geometrical factors of the apparatus, the characteristic response time of the normal force measuring system in some cases, might not be small in comparison to the characteristic time of the testing fluid. The factors influencing the characteristic response time of the normal force measuring system are determined and a criterion is established which should be met to minimize the influence of the instrument response on the rheological measurements of the test fluid. Time constants as functions of geometrical and experimental factors associated with gap separation velocity for two Newtonian incompressible liquids are measured and compared with the calculated values. The theory is qualitatively in agreement with the experimental findings, yet for some cases disagreements of up to 43% between the measured and calculated time constants are observed. The dominant effect of gap angle is also confirmed.
Re-envisioning the Paradigm for Oncology Electronic Health Record Documentation by Paying for What Matters for Patients, Quality, and Research
Authors: Gabriel Peter E. , Singh Aditi P. , Shulman Lawrence N.
Published: January 2023

This Viewpoint discusses re-envisioning and incentivizing a unique approach to oncology electronic health record documentation.
Cobalt‐Catalyzed Diastereo‐ and Enantioselective Hydroarylation of Cyclopropenes with Arylboronic Acids
Authors: Zhang Jiwu , Wang Lei , Chong Qinglei , Meng Fanke
Published: January 2023

Catalytic diastereo‐ and enantioselective hydroarylation of 3,3‐disubstituted cyclopropenes with easily accessible arylboronic acids promoted by a chiral phosphine‐Co complex is presented. Such a process represents an unprecedented Co‐catalyzed approach for direct introduction of a variety of aryl groups onto the cyclopropane motif, affording multisubstituted cyclopropanes in up to 86% yield with greater than 95 : 5 dr and 99 : 1 er.
A deep learning ensemble approach for predicting tropical cyclone rapid intensification
Authors: Chen Buo‐Fu , Kuo Yu‐Te , Huang Treng‐Shi
Published: January 2023

Predicting rapid intensification (RI) of tropical cyclones (TCs) is critical in operational forecasting. Statistical schemes rely on human‐driven feature extraction and predictor correlation to predict TC intensities. Deep learning provides an opportunity to further improve the prediction if data, including satellite images of TC convection and conventional environmental predictors, can be properly integrated by deep neural networks. This study shows that deep learning yields enhanced intensity and RI prediction performance by simultaneously handling the human‐defined environmental/TC‐related parameters and information extracted from satellite images. From operational and practical perspectives, we use an ensemble of 20 deep‐learning models with different neural network designs and input combinations to predict intensity distributions at +24 h. With the intensity distribution based on the ensemble forecast, forecasters can easily predict a deterministic intensity value demanded in operations and be aware of the chance of RI and the prediction uncertainty. Compared with the operational forecasts provided for western Pacific TCs, the results of the deep learning ensemble achieve higher RI detection probabilities and lower false‐alarm rates.
Integrating mobile learning and SPOC‐based flipped classroom to teach a course in water supply and drainage science and engineering
Authors: Zhang Hui , Zhang Jie , Wang Junping , Zhang Haihan
Published: January 2023

To promote the combination of mobile learning (m‐learning) in new courses contexts and improve students' learning outcomes, an integrated method of m‐learning and small private online course (SPOC)‐based flipped classroom was proposed and used for teaching the “hydrology” course at Xi'an University of Architecture and Technology (XAUAT). The offering of the new methodology was composed of preclass (knowledge acquisition), in‐class (knowledge internalization), and after‐class (knowledge application) stages, and the WeChat applet Mu classroom with m‐learning technology was adopted in the in‐class stage. To improve the teacher–student interactions and communication, several interactive activities were designed based on Mu classroom, including random roll calls, open questions, objective questions, discussion, and extended discussion. After using the integrated method, the average score of each final exam was improved significantly (p < .05), and the failed (<60) percentage was decreased significantly (p = .002 < .01). Positive correlation between the scores of in‐class quizzes and discussion and final exam were obtained (R2 = .530, p < .001), indicating that students' outcomes were greatly affected by mobile learning. Moreover, positive feedback from students' questionnaires confirmed that the integrated approach was effective and could motivate students' learning interests and knowledge understanding.
Sustainable Modification of Chitosan Binder for Capacitive Electrodes Operating in Aqueous Electrolytes
Authors: Bargnesi Luca , Rozzarin Arianna , Lacarbonara Giampaolo , Tombolesi Serena , Arbizzani Catia
Published: January 2023

Biopolymers emerged in recent years as a promising alternative for a more sustainable manufacturing of electrochemical energy storage systems. In fact, for environmentally friendly aqueous systems, fluorinated polymers are usually adopted. For this reason, substituting these polymers with water processable binders could improve the overall environmental impact of the device. In this study, a low – cost and environmentally friendly modification of chitosan binder for self‐standing activated carbon electrodes operating in Na ion, aqueous electrochemical double layer capacitors is reported and discussed.
Chiral Alkynyl‐Stabilized Ag/Cu Nanoclusters from Spontaneous Resolution
Authors: Sun Xueli , Guo Zipeng , Tang Xiongkai , Xu Zhen , Sun Jing , Xie Zhenlang , Nan Zi‐Ang , Guo Shuo , Shen Hui
Published: January 2023

Intrinsically chiral metal nanoclusters with crystal structure are highly desirable to gain deep insights into chirality origin of chiral nanostructures and understand structure‐and‐property relationship of heterogeneous catalysts in asymmetric catalysis. Although several strategies including the use of chiral ligands and high‐performance liquid chromatography have been routinely employed to gain nanoclusters with inherent chirality, another simple methodology of spontaneous resolution remains largely unexplored. In this work, we report the isolation of homochiral Ag/Cu nanoclusters stabilized by alkynyl ligands from spontaneous self‐resolution, which represents a pioneering example in the realm of alkynyl‐protected metal nanoclusters. The cluster, with the formula of [Ag12Cu7(dppe)3(RC≡C)14]3+, has been prepared in one‐pot, with the high yield of 71%. Structural anatomy reveals that the metal architecture, metal‐ligand interface and ligand arrangement of the cluster all display chirality. The cluster features superatomic free electrons, implying its potential application in specific fields. This work not only offers strategic guidance for the simple synthesis of alkynyl‐protected metal nanoclusters with inherent chirality in an all‐achiral environment, but also displays the hierarchical chirality of cluster moieties at molecular level.
Facile synthesis of ordered mesoporous molybdenum carbide electrocatalysts for high‐performance hydrogen evolution reaction
Authors: Zheng Man , Cao Bohan , Liu Jiaxian , Shi Kun , Zhang Yufan , Wang Huan
Published: January 2023

In this study, a simple method was designed to prepare ordered mesoporous carbons embedded with molybdenum without any extreme conditions. We prepared three different ordered molybdenum carbide materials with mesoporous structures to explore the influence of the structure of molybdenum‐based materials on the HER catalytic efficiency. The ordered mesoporous molybdenum carbide catalysts (CMK‐3‐MoCx, fCMK‐3‐MoCx, CMK‐8‐MoCx) were characterized by SEM, TEM, XRD, nitrogen adsorption‐desorption and XPS. The HER is catalyzed efficiently on the three electrocatalysts, fCMK‐3‐MoCx shows the best HER electro‐catalytic performance with a small onset potential of −0.06 V vs. RHE, a low tafel slope of 66 mV dec−1 and a small over‐potential value of 89 mV at 10 mA cm−2. This excellent performance on HER is due to its high specific surface area and highly ordered mesoporous structure that resulted in excellent proton transport efficiency and high electron transfer rate. Our results provide a new research direction for the application of flat ordered mesoporous structures in catalysis.
The Australopithecus assemblage from Sterkfontein Member 4 (South Africa) and the concept of variation in palaeontology
Authors: Beaudet Amélie
Published: January 2023

Interpreting morphological variation within the early hominin fossil record is particularly challenging. Apart from the fact that there is no absolute threshold for defining species boundaries in palaeontology, the degree of variation related to sexual dimorphism, temporal depth, geographic variation or ontogeny is difficult to appreciate in a fossil taxon mainly represented by fragmentary specimens, and such variation could easily be conflated with taxonomic diversity. One of the most emblematic examples in paleoanthropology is the Australopithecus assemblage from the Sterkfontein Caves in South Africa. Whereas some studies support the presence of multiple Australopithecus species at Sterkfontein, others explore alternative hypotheses to explain the morphological variation within the hominin assemblage. In this review, I briefly summarize the ongoing debates surrounding the interpretation of morphological variation at Sterkfontein Member 4 before exploring two promising avenues that would deserve specific attention in the future, that is, temporal depth and nonhuman primate diversity.
Crimean‐Congo hemorrhagic fever outbreak in Pakistan, 2022: A warning bell amidst unprecedented floods and COVID 19 pandemic
Authors: Tabassum Shehroze , Naeem Aroma , Khan Maleeka Zamurad , Mumtaz Nimra , Gill Saima , Ohadi Laya
Published: January 2023

Crimean‐Congo hemorrhagic fever (CCHF) is an infection caused by a tick‐borne virus (genus: Nairovirus, family: Bunyaviridae). The most important vector for CCHF is the ixodid tick. Along with tick bite, direct contact with the virus‐affected animal is responsible for its spread. Pakistan witnessed its first case of CCHF in 1976 and has been a major victim of CCHF for years, but spikes in cases are seen after Eid‐ul‐Adha, an Islamic festival involving the sacrifice of cattle. The disease, in particular, is common among butchers, veterinarians, and livestock workers. From the start of this year till June 22, 2022, a total of four cases have been reported across the country. Pakistan faces major challenges in combating CCHF every year due to its specific geographical position and a majority of the population being involved with animal husbandry. There is no approved vaccine for its prevention. All these factors contribute to the burden on the already weakened healthcare system of Pakistan. Strict actions should be taken to contain the spread of the disease. The need of the hour is to engage the general population, raise awareness, and develop policies to ensure disease surveillance. This should be accompanied by fostering collaboration among animal and human health departments for efficient communication and early intervention. The focus should be on medical research to find an efficacious treatment and prophylaxis for the CCHF virus, which will be the cornerstone of future CCHF prevention and control strategies.