bluuebunny/crossref_metadata_2025 huggingface dataset:
A Multi-Aspect Modeling Method for Service Flow Simulation Using Scene Transition Nets (STNs)
Authors: Tateyama Takeshi , Mikoshiba Satoshi , Kimita Koji , Watanabe Kentaro , Chiba Ryosuke , Shimomura Yoshiki , Kawata Seiichi
Published: September 2013

Recently, a new academic field, “service engineering” has been very actively investigated. However, there are few effective methods and tools to simulate and evaluate services designed based on the concept of service engineering. In the past, the authors proposed a service flow simulation method using scene transition nets (STN) which is a graphic modeling and simulation method for discrete-continuous hybrid systems. However, this method does not consider how to model and simulate complex service flows including multiple layered, parallel, and interrupted structures and it is difficult to construct STN models of such complex systems using the existing STN concepts. In this paper, the authors propose a new STN modeling method using “multi-aspect STN modeling “ concepts in order to provide easy methods for modeling of such complex services. The experimental results for the modeling and simulation of a nursing service demonstrate the effectiveness of the proposed method.
A Computational Strategy for Design and Implementation of Equipment That Addresses Sustainable Agricultural Residue Removal at the Subfield Scale
Authors: Muth David , Koch Joshua , McCorkle Douglas , Bryden Kenneth
Published: September 2013

Agricultural residues are the largest potential near term source of biomass for bioenergy production. Sustainable use of agricultural residues for bioenergy production requires consideration of the important role that residues play in maintaining soil health and productivity. Innovation equipment designs for residue harvesting systems can help economically collect agricultural residues while mitigating sustainability concerns. A key challenge in developing these equipment designs is establishing sustainable reside removal rates at the sub-field scale. Several previous analysis studies have developed methodologies and tools to estimate sustainable agricultural residue removal by considering environmental constraints including soil loss from wind and water erosion and soil organic carbon at field scale or larger but have not considered variation at the sub-field scale. This paper introduces a computational strategy to integrate data and models from multiple spatial scales to investigate how variability of soil, grade, and yield within an individual cornfield can impact sustainable residue removal for bioenergy production. This strategy includes the current modeling tools (i.e., RUSLE2, WEPS, and SCI), the existing data sources (i.e., SSURGO soils, CLIGEN, WINDGEN, and NRCS managements), and the available high fidelity spatial information (i.e., LiDAR slope and crop yield monitor output). Rather than using average or representative values for crop yields, soil characteristics, and slope for a field, county, or larger area, the modeling inputs are based on the same spatial scale as the precision farming data available. There are three challenges for developing an integrated model for sub-field variability of sustainable agricultural residue removal—the computational challenge of iteratively computing with 400 or more spatial points per hectare, the inclusion of geoprocessing tools, and the integration of data from different spatial scales. Using a representative field in Iowa, this paper demonstrates the computational algorithms used and establishes key design parameters for an innovative residue removal equipment design concept.
Cooperative Micromanipulators for 3D Micromanipulation and Assembly
Authors: Cappelleri David J. , Fu Zhenbo
Published: September 2013

In this paper we demonstrate coordinated control of multiple micromanipulators for use in automated 3D micromanipulation and assembly tasks. We build on our previous work on caging micromanipulation by using a similar methodology and extend it to the 3D case. Simultaneous movements of the coordinated micromanipulators normal to the caging polygon allows for the transition of 2D planar micro-caging grasps to micro-force closure grasps suitable for 3D micro-transporting tasks. Experimental results illustrate the success and accuracies of both the micro-grasps’ transitions and 3D pick-and-place tasks. Finally, the new 3D transportation primitive is used in conjunction with our previous 2D micromanipulation primitives and an encoded XY stage to semi-autonomously execute some representative 3D microassembly tasks.
Material Property Manipulation of Photopolymer Vibration Energy Harvesters
Authors: Baker Evan , Reissman Timothy , Zhou Fan , Sun Cheng
Published: September 2013

The inefficiency in converting naturally occurring vibration frequencies (sub-100 Hz) to electrical energy continues to be a major obstacle for miniaturized vibration energy harvesters. In a recent work, we addressed this issue by introducing photopolymer-based designs, using projection microstereolithography which exhibited 61 Hz resonant frequencies due to low elastic moduli and low flexural rigidity using a three-dimensional, helical coil design. In this paper, we extend upon those findings to report on a post-process technique which uses ultraviolet exposure time to manipulate the material properties of photopolymer-based vibration energy harvesters. The results show with 1–3 minutes of post-exposure, an effective elastic modulus variation from 399–904 MPa and a parasitic damping change from 0.0595–0.0986 kgs−1. Likewise, resonant frequency shifts of 53.5–805 Hz and power output increase from 56.5 to 120.4 μW (when excited at a constant acceleration of 6.06±0.06 ms−2) are achieved, without geometry changes and using the same photopolymer material.
Enhancing Visual Thinking in a Toy Design Course Using Freehand Sketching
Authors: Taborda Elkin , Chandrasegaran Senthil K. , Kisselburgh Lorraine , Reid Tahira , Ramani Karthik
Published: September 2013

Engineering graduates in advancing economies are not only expected to have engineering knowledge, but also use them in creative and innovative ways. The importance of visual thinking has been critical for creativity and innovation in design. However, today’s engineering students are proficient in detailed design tools but lacking in conceptual design and ideation, and engineering curricula needs to develop a more effective framework for teaching visual thinking. In this paper, we report our efforts to embed principles of design thinking and visual thinking practices, like McKim’s “seeing, imagining and drawing” cycle [1]. We use a toy design course in mechanical engineering for our pilot study as a scaffold for introducing these principles in an engaging, creative, and fun environment. We introduced free-hand sketching as a tool for visual thinking during the design and communication of concepts. We also report the impact of these changes through information gleaned from student feedback surveys and analysis of design notebooks. We use our findings to propose ways to provide the students with a set of balanced techniques that help them in visual thinking, communication, and design. An improved implementation of this experience is discussed and future work is proposed to overcome barriers to thinking and communication.
Uncertainty Quantification in Nonlinear Resonant MEMS
Authors: Goyal Rajat , Bajaj Anil K.
Published: September 2013

This work is focused on Uncertainty Quantification (UQ) in a nonlinear MEMS T-beam structure exhibiting 1:2 autoparametric internal resonance. The study is presented by elaborating on the sources of uncertainty in fabrication and operation of the device and their quantification. Nonlinear response of the system is formulated by using a two-mode model constructed with lowest two linear modes of the structure in conjunction with the nonlinear Lagrangian representing the dynamics of the beam structure as well as the excitation mechanism. Thus UQ for the nonlinear resonant MEMS is carried out in two steps. First, propagation and quantification in linear analysis outputs namely mode shapes, natural frequencies and tuning, and secondly, UQ on nonlinear response obtained from averaged equations determined by the averaged Lagrangian. In this paper, applications of UQ techniques on linear part are presented and effects of various parameteric uncertainties on model output are brought out. Sensitivity analysis is performed to reduce the number of parameters and a comparison of sensitivity analysis with sampling is done to establish the accuracy of the method. Response surface analysis is performed using generalized polynomial chaos (gPC) to generate an analytical expression for multi-dimensional uncertainty. A detailed description of the gPC collocation method is also presented. A comparison of response surface method with direct sampling is done to illustrate the efficiency and accuracy of gPC collocation technique for up to 5 uncertain parameters.
Topology Optimization of Blank Geometry for the Sheet Forming Process
Authors: DorMohammadi Saber , Rouhi Mohammad , Rais-Rohani Masoud
Published: September 2013

The newly developed element exchange method (EEM) for topology optimization is applied to the problem of blank shape optimization for the sheet-forming process. EEM uses a series of stochastic operations guided by the structural response of the model to switch solid and void elements in a given domain to minimize the objective function while maintaining the specified volume fraction. In application of EEM to blank optimization, a sheet forming simulation model is developed using Abaqus/Explicit. With the goal of minimizing the variability in wall thickness of the formed component, a subset of solid (i.e., high density) elements with the highest increase in thickness is exchanged with a consistent subset of void (i.e., low density) elements having the highest decrease in thickness so that the volume fraction remains constant. The EEM operations coupled with finite element simulations are repeated until the optimum blank geometry (i.e., boundary and initial thickness) is found. The developed numerical framework is applied to blank optimization of a benchmark problem. The results show that EEM is successful in generating the optimum blank geometry efficiently and accurately.
Flow Analysis of Straight and Swept Edge Wind Turbine Blades in Blade and Wake Regions
Authors: Amano Ryoichi S. , Mohan Das Pradeep Mohan , Alnakhli Mohammed
Published: September 2013

This paper presents the comparison of the wake sizes and shapes between two different designs of a horizontal axis wind turbine (HAWT) rotor blades; one a straight edged and the other with a backward sweep. The straight edge blade was constructed so that it is optimal for on coming wind and rotation speeds with 7m/s and 23rpm. The blade has a length of 20m and uses a constant airfoil cross section. The swept edge blade has the same characteristics as the straight edge except for the trajectory of the edge. Each swept blade has the same cross section with the same dimensions at the same distance from the hub as its corresponding section in the straight edge blade. The analysis was done at a range of velocities from 7 m/s to 18 m/s. It was confirmed that the stall region observed by previous studies is in fact due to the flow separation throughout the span of the blade for both the straight and swept blades. A comparison of wake lengths for both straight and swept blades was done for a range of wind velocities. It was shown that the wake length for swept edged blades were longer than for straight blades and both start decreasing beyond the stall region. From a comparison of flow separation angles from experiments and CFD computations, both were observed to follow the same trends at high Reynolds numbers.
Water Aeration in Wastewater Treatment
Authors: Amano R. S. , Alkhalidi Ammar , Bryar Patrick , Alwayel Wayel
Published: September 2013

The primary objective of this paper is to examine ways to increase the efficiency of water aeration process. This objective was completed through the use of a propeller and fan blade designs. Both Standard oxygen transfer efficiency (SOTE) and power reclamation were analyzed. Results of SOTE analysis indicated a decrease in efficiency, when compared to the standard model air diffuser. While the propeller design was able to successfully breakup the forming bubble column, the system reduced the circulatory currents that create mixing within the experimental tank. Results indicate a small SOTE drop, throughout the system. Power reclamation was able to yield, at a peak depth of 25cm (10 in) below the top water surface, 0.8W, with input energy of approximately 45 W resulting in reclamation of 1.8% of the power put into the system. This data was retrieved at a volumetric flow rate of 9.4 × 10−4 m3/s (2 CFM) with a pressure of 55kPa (8psi).
Joint Design for 3-D Printing Non-Assembly Mechanisms
Authors: Song Xuan , Chen Yong
Published: September 2013

The layer-based additive manufacturing (AM) processes can directly fabricate sub-systems with multiple components during the building process. Novel applications in robotics and many others have been demonstrated by removing the need of component assembly. However, the AM processes also have inferior accuracy compared to the Computer Numerical Control (CNC) machining process. Hence the joint clearance that can be achieved in a 3D-printed mechanism is large. This would significantly limit the use of AM in directly building movable sub-systems without further assembly operations after the building process. To reduce the joint clearance, we present a novel joint design by considering the fabrication limitation of AM processes. A novel marker structure is developed for various types of joints including cylindrical pin joints. The relation of the marker design and the rotation performance of the 3D-printed joint is modeled. Test cases based on the Stereolithography Apparatus (SLA) process have been performed to verify the effectiveness of the developed joint design. Compared to the traditional pin joint design, the new design can achieve a smaller clearance during rotation while still be able to be fabricated by the SLA process. Consequently its rotation performance can be improved.
Nonlinear Dynamics of Electrostatically Actuated Coupled MEMS Parallel Cantilever Resonators
Authors: Caruntu Dumitru I. , Taylor Kyle N.
Published: September 2013

This paper deals with the nonlinear response of a coupled cantilever system composed of two micro beams electrostatically actuated. The AC frequency of actuation is near natural frequency of the cantilevers. The two cantilevers are identical. Lagrange equations are used to develop a mathematical model of the system. These equations of motion are nondimensionalized and subjected to the method of multiple scales in order to find steady state solutions. Alternating Current (AC) and Direct Current (DC) actuation voltages are applied between the first cantilever and ground plate with DC voltage applied between the first and second cantilevers. Amplitude-frequency and phase-frequency responses of the system are provided for typical micro beam system structures.
Integrating CAD and Nano-Indentation for Complex Lithography
Authors: Xu Kangmin , Yang Seung-Cheol , Qian Xiaoping
Published: September 2013

We present an approach for producing complex nanoscale patterns by integrating computer-aided design (CAD) geometry processing with an atomic force microscope (AFM) based nanoindentation process. Surface modification is achieved by successive nano-indentation using a vibrating tip. By incorporating CAD geometry, this approach provides enhanced design and patterning capability for producing geometric features of both straight lines and freeform B-splines. This method automatically converts a pattern created in CAD software into a lithography plan for successive nanoindentation. For ensuring reliable lithography, key machining parameters including the interval of nanoindentation and the depth of nanogrooves have been investigated, and a proper procedure for determining the parameters has been provided. Finally, the automated nanolithography has been demonstrated on poly methylmethacrylate samples. It shows the robustness of the CAD integrated, AFM based nanoindentation approach in fabricating complex patterns.
Modeling the Obsolescence of Critical Human Skills Necessary for Supporting Legacy Systems
Authors: Sandborn Peter , Prabhakar Varun J. , Kusimo Abisola
Published: September 2013

Obsolescence of human skills impacts the support of long field life systems. Human skills obsolescence is a growing problem for organizations as they try to estimate and mitigate the effects of an aging workforce with specialized (and possibly irreplaceable) skill sets. Difficulties with skills obsolescence have been reported in a number of industries including industrial controls, aerospace, and military systems, all product sectors that must support critical systems for 20–30 years or longer.

Common workforce planning models do not generally address the obsolescence of skills. Rather, they implicitly assume lost human resources are always replenishable. Nearly all of the existing research associated with the obsolescence of skills focuses on the opposite of the problem addressed in this paper, i.e., workers have skills that are obsolete and therefore need to be retrained in order to be employable. Alternatively, this paper addresses the lack of workers with the necessary skill set and the inability to replace them. This paper describes a model for the obsolescence of skills and skilled worker retention. This research provides a way to quantitatively address the problem of skills obsolescence and provides a basis upon which to estimate the cost of future system support.
Vocal communication of wild parrots
Authors: Bradbury Jack
Published: September 2013

Field studies of four sympatric parrot species in Costa Rica are revealing several possible functions for the well-known ability of parrots to mimic new sounds throughout life. Despite earlier suggestions that this might facilitate exchanges of environmental information, all data so far suggest that vocal mimicry in the wild is associated with mediation of the fission/fusion of groups of parrots and/or of conflicts between mated pairs. Recent results using array recording and interactive playback will be summarized, and several technical problems created by the mechanisms of parrot vocal signal production discussed. [Research supported by NSF Grant IBN-022927 and by continued encouragement and logistics provided by the staff of the Area Conservacion Guanacaste (Costa Rica).]
Echolocation in wild toothed whales
Authors: Tyack Peter L. , Johnson Mark , Madsen Peter Teglberg , Zimmer Walter M. X.
Published: September 2013

Don Griffin showed more than 50 years ago that bats echolocate for orientation and to capture prey. Experiments also demonstrated that captive dolphins can echolocate; more recent work parallels Griffin’s work with bats in the wild. Digital acoustic recording tags were attached to sperm and beaked whales, Ziphius cavirostris and Mesoplodon densirostris, to record outgoing clicks and incoming echoes. The sperm whale data show echoes from the sea surface and seafloor, which are probably used for orientation and obstacle avoidance. When diving, sperm whales adjust their interclick interval as they change their pitch angle, consistent with the hypothesis that they are echolocating on a horizontal layer at the depth at which they will feed. This suggests that they may be listening for volume reverberation to select a prey patch. The beam pattern of sperm whales includes a narrow, forward-directed high-frequency beam probably used for prey detection, and a broader, backward-directed lower-frequency beam probably used for orientation. Beaked whales produce directional clicks with peak frequencies in the 25–40-kHz region. Echoes from individual prey items have been detected from clicks of beaked whales. This opens a new window into the study of how animals use echolocation to forage in the wild.
Reciprocity calibration of hydrophones at various temperatures in the MHz frequency range
Authors: Labuda Cecille , Church Charles C. , Raymond Jason
Published: September 2013

Calibration of an Imotec 300/24/62 bilaminar PVDF needle hydrophone and a Sonora Medical S4-155 membrane hydrophone over the frequency range 1–12 MHz at different temperatures (3–37°C) was conducted using a reciprocity method. Calibration data received from hydrophone manufacturers are given for a range of frequencies but usually at only one temperature, typically room temperature. If the hydrophone must be used at a temperature different than the one at which it was calibrated, a new calibration must be performed. The reciprocity method employed in this study makes use of pairs of unfocused reciprocal transducers (send/receive) to provide redundant measurements and simplicity. The method was tested by calibrating a hydrophone for which the manufacturers calibration data were available. Our test data, with error bars of about 1.7 dB, fell within the range of the manufacturers data, which have error bars of about 1 dB. The results for the passive PVDF probe (Imotec) showed that sensitivity decreased by about one order of magnitude as the temperature decreased from 22°C (i.e., room temperature) to 3°C. A small increase is observed as temperature rises from 22°C to 37°C although the sensitivity remains about the same order of magnitude.
Nonlinear seismo-acoustic landmine detection
Authors: Donskoy Dimitri
Published: September 2013

The seismo-acoustic methods are among the most promising emerging techniques for the detection of landmines. Numerous field tests have demonstrated that buried landmines manifest themselves at the surface through linear and nonlinear responses (or signatures) to acoustic/seismic excitation at the frequencies below 1000 Hz. The linear signatures are due to lower impedance of soil above softer mine, especially in the vicinity of mines resonance. The nonlinear signatures are explained by high contact nonlinearity at the mine–soil interface. These phenomena are utilized in high provability/low false alarm detection methods pioneered by University of Mississippi (linear detection) and Stevens Institute of Technology (nonlinear detection). A simple mass-spring model of the mine-soil system [Donskoy et al., J. Acoust. Soc. Am. (2002)] explains and provides an analytical tool for analysis and prediction of both: linear and nonlinear signatures with respect to depths, soil, and mine types. This presentation provides an overview of theoretical and experimental investigations conducted at Stevens over the last 4 years with the emphasis on nonlinear detection techniques. Among major accomplishments are discovery and explanation of mines resonance behavior; soil/depth effect on buried mines resonances; discovery and analysis of nonlinear acoustic interactions at the soil–mine interface; and development of nonlinear quadratic and intermodulation detection algorithms based on dual-frequency excitation.
Demonstration of an end-fire array Rayleigh wave source for a seismo-acoustic sonar
Authors: Baker Steven R. , Rumph Steven E.
Published: September 2013

A linear array of four vertical-motion sources was deployed on the sand in the near-surf zone of Del Monte Beach, Monterey, CA. The sources were spaced 25 cm apart (approximately one-quarter wavelength at 100 Hz, the nominal operating frequency) and were driven with a transient signal in a sequential fashion so as to preferentially radiate Rayleigh waves in one end-fire direction. Beam patterns were measured at a radius of 3.5 m. Measurements were made with the array directing the radiation toward, away from, and parallel to the surf line. In general, results were in fair agreement with simple (nondispersive) theory, except for the depth of the nulls. A measured front-to-back radiation suppression of approximately 15 dB was routinely achievable.
Psychophysical and speech results from the penetrating auditory brainstem implant (PABI)
Authors: Shannon Robert V. , Robert Mark E. , Otto Steve
Published: September 2013

The penetrating auditory brainstem implant (PABI) is a prosthetic device that delivers sound information to the brain via microstimulation of the cochlear nucleus. The design of the speech processor is similar to that in a cochlear implant. Surface electrodes are placed in the lateral recess of the IV ventricle, adjacent to the cochlear nucleus. Penetrating microelectrodes are inserted into the ventral cochlear nucleus. Threshold measures in two patients confirm intra-nuclear placement. Stimulation of the penetrating microelectrodes produced a full range of loudness sensations as well as a wide range of pitch sensations. Initial psychophysical measures show excellent temporal resolution (forward masking, gap detection, modulation detection) on the penetrating electrodes in one patient and poor temporal performance in another. Speech understanding was moderate, with one patient receiving primarily a supplement to lip-reading, while the other patient received modest open-set speech understanding on the third day following initial stimulation. Ongoing studies will characterize the interference between and within surface and penetrating electrode systems and the ability of the patient to integrate speech information across the two types of electrodes. [Work supported by NIDCD Contract N01-DC-00-11.]
Detection and F0 discrimination of harmonic complex tones in the presence of concurrent complexes
Authors: Micheyl Christophe , Oxenham Andrew
Published: September 2013

This study measured the level of target harmonic complex tones, relative to simultaneous concurrent harmonic or inharmonic maskers, necessary for (a) target detection and (b) discrimination of the target F0. Depending on the condition, the F0 of the target was around 100, 200, or 400 Hz and the average F0 of the masker was either equal to this or 7 semitones lower or higher. Target and maskers were bandpass filtered between 1200 and 3600 Hz (48-dB/octave slopes). Low-pass noise masked distortion products. Masked thresholds in the target-detection task were generally higher when the average F0 of the masker was lower than that of the target, and were also higher for inharmonic than for harmonic maskers. In the F0 discrimination task, average F0 differences between the target and masker tones consistently improved masked thresholds at the highest F0 used (400 Hz) but not the lowest (100 Hz). Temporal asynchronies between the target and masker and reduced masker–F0 uncertainty had similar effects. These results suggest that peripheral frequency resolution may limit the ability to benefit from auditory segregation cues for both the detection and discrimination of harmonic complex tones embedded in other tones. [Work supported by NIDCD R01DC05216.]
An SII-based approach to predict the speech intelligibility in fluctuating noise for normal-hearing listeners
Authors: Rhebergen Koenraad S. , Versfeld Niek J.
Published: September 2013

The speech intelligibility index (SII) is frequently used to predict the speech intelligibility for speech in a given interfering noise. However, the SII model only has been validated for speech in stationary noise. Since the SII departs from speech and noise spectra, it does not take into account any fluctuations in the masking noise. Hence, the model will yield similar SII values, regardless of the degree of fluctuation. In contrast, from the literature it is clear that normal-hearing listeners can benefit from the fluctuations in the noise. The present paper describes an SII-based approach to model speech reception thresholds (SRTs) for speech in both stationary and fluctuating noise. The basic principle of this approach is that both speech and noise signals are partitioned into small time frames. Within each time frame, the conventional SII is determined, yielding the speech information available to the listener at that time frame. Next, the SII values of these time frames are averaged, resulting in the SII for that particular condition. With the aid of SRT data from the literature, it will be shown that this approach can give a good account for most existing data.
Scattering from marine sediments with discrete inclusions
Authors: Ivakin Anatoliy N.
Published: September 2013

A model of scattering in sediments with discrete inclusions is developed allowing prediction of bottom reverberation, given material parameters of the sediment and inclusions and their size distribution, which can be depth dependent. The frequency-angular dependencies of the seabed scattering strength for various types of the sediment and inclusions are calculated and discussed. An environmental data set obtained at SAX99 site (near Walton Beach, FL), including the sediment particle size distribution and roughness spectra, was used to compare contributions of volume and roughness components of the seafloor scattering. It is shown, in particular, that contribution of gravel and shell inclusions and coarse sand fraction in total scattering can be dominating (over roughness) at high frequencies (about 100 kHz and higher) and grazing angles above critical (about 30 deg) while roughness at SAX99 site is likely a dominating mechanism of bottom scattering at lower frequencies and grazing angles below critical. A combined model, taking into account both roughness and volume discrete scattering, is shown to be a good descriptor of bottom reverberation in a wide frequency-angular range. Possibilities for inversion of various sediment parameters from backscattering data are discussed. [Work supported by ONR, Ocean Acoustics.]
Aerial hearing sensitivity in some pinnipeds is comparable to that of humans
Authors: Reichmuth Kastak Colleen , Kastak David , Holt Marla M. , Schusterman Ronald J. , Southall Brandon L.
Published: September 2013

Aerial hearing sensitivity was measured in pinnipeds in a sound attenuating, hemi-anechoic chamber. Thresholds at 12 frequencies between 0.1 and 32.5 kHz were obtained behaviorally for three individuals (a California sea lion, a harbor seal, and a northern elephant seal) and compared to thresholds obtained using headphones in less controlled testing environments. The thresholds measured in the chamber revealed the expected relative changes in sensitivity with frequency; however, the absolute sensitivities were much better than had been previously measured. Harbor seal thresholds were on average 25 dB lower with best sensitivity of −2 dB (re: 20 μPa) at 3.2 kHz. Elephant seal thresholds averaged 23 dB lower with best sensitivity of 27 dB (re: 20 μPa) at 0.4 kHz. Thresholds for the California sea lion were also much lower than expected, with best sensitivity of 1 dB (re: 20 μPa) at 12 kHz. The thresholds measured for the sea lion and harbor seal rival those of human subjects at some frequencies, and suggest that previously reported aerial hearing thresholds in pinnipeds wwere significantly noise limited. Further, the results indicate that these pinnipeds have greater sensitivity in air than in water when comparisons are made in terms of sound pressure.
Aided speech recognition in single-talker competition by elderly hearing-impaired listeners
Authors: Coughlin Maureen , Humes Larry
Published: September 2013

This study examined the speech-identification performance in one-talker interference conditions that increased in complexity while audibility was ensured over a wide bandwidth (200–4000 Hz). Factorial combinations of three independent variables were used to vary the amount of informational masking. These variables were: (1) competition playback direction (forward or reverse); (2) gender match between target and competition talkers (same or different); and (3) target talker uncertainty (one of three possible talkers from trial to trial). Four groups of listeners, two elderly hearing-impaired groups differing in age (65–74 and 75–84 years) and two young normal-hearing groups, were tested. One of the groups of young normal-hearing listeners was tested under acoustically equivalent test conditions and one was tested under perceptually equivalent test conditions. The effect of each independent variable on speech-identification performance and informational masking was generally consistent with expectations. Group differences in the observed informational masking were most pronounced for the oldest group of hearing-impaired listeners. The eight measures of speech-identification performance were found to be strongly correlated with one another, and individual differences in speech understanding performance among the elderly were found to be associated with age and level of education. [Work supported, in part, by NIA.]
TADA: An enhanced, portable Task Dynamics model in M
A
T
L
A
B
Authors: Nam Hosung , Goldstein Louis , Saltzman Elliot , Byrd Dani
Published: September 2013

A portable computational system called TADA was developed for the Task Dynamic model of speech motor control [Saltzman and Munhall, Ecol. Psychol. 1, 333–382 (1989)]. The model maps from a set of linguistic gestures, specified as activation functions with corresponding constriction goal parameters, to time functions for a set of model articulators. The original Task Dynamic code was ported to the (relatively) platform-independent MATLAB environment and includes a MATLAB version of the Haskins articulatory synthesizer, so that articulator motions computed by the Task Dynamic model can be used to generate sound. Gestural scores can now be edited graphically and the effects of gestural score changes on the models output evaluated. Other new features of the system include: (1) A graphical user interface that displays the input gestural scores, output time functions of constriction goal variables and articulators, and an animation of the resulting vocal-tract motion; (2) Integration of the Task Dynamic model with the prosodic clock-slowing, pi-gesture model of Byrd and Saltzman [J. Phonetics 31, 149–180 (2003)]. This now allows prosody-driven slowing to be applied to the full set of active gestures and its effects to be evaluated perceptually. [Work supported by NIH.]
Modal scattering and T-waves: Sediment amplification and source effects
Authors: Odom Robert I. , Soukup Darin J.
Published: September 2013

If the Earth were a plane-layered semi-infinite half-space or a radially symmetric sphere oceanic, T-waves could not exist. This is apparent because the source depth of T-wave producing earthquakes is greater than the depth at which the low order modes comprising the T-waves have any significant amplitude. Bottom roughness provides a mechanism by which energy from high order source modes can be scattered into the lower order modes. The efficiency of this scattering is improved when there is a layer of sediments overlying the higher speed upper ocean crust. Some of the source modes develop a large anti-node, reminiscent of a Scholte wave, at the water sediment interface. Bottom roughness serves as a sheet of secondary sources placed directly on the anti-node of these modes, and contributes a significant amount of energy to the T-waves. However, a significant fraction of the total T-wave energy is also provided by small scattered contributions from many higher modes of the continuum spectrum, which is modeled using the locked mode approximation. Source mechanism modeling of T-wave excitation shows that normal fault earthquakes are inefficient generators of T-waves.
Experimental high-intensity focused ultrasound lesion formation in cardiac tissue
Authors: Muratore Robert , Kalisz Andrew , Lee Paul , Lizzi Frederic , Fujikura Kana , Otsuka Ryo , Homma Shunichi
Published: September 2013

High-intensity focused ultrasound (HIFU) (4.5–7.5 MHz) was used to form lesions in cardiac tissue, with an ultimate objective of treating conditions such as hypertrophic cardiomyopathy and ventricular tachycardia. Ultrasound attenuation coefficients were experimentally determined in vitro for calf myocardial tissue, both muscle and pericardial fat. These coefficients were employed in computational models of linear beam propagation, tissue heating profiles and thermal lesion formation for a variety of focused transducers. Modeling was performed for continuous and pulsed exposures. These models suggested initial power levels and exposure durations for in vitro experiments on calf ventricles and septa and ex vivo experiments on canine whole hearts. Repeatability of lesion size and placement was studied as power and exposure parameters varied around the initial values. With these experimental results, power and exposure parameters were selected to create lesions in vivo in canine ventricles and septa in open-chest, anesthetized dogs. Pulsed exposures were synchronized to cardiac and respiration cycles to ensure accurate placement of the lesions. These initial in vivo experiments showed that HIFU treatments in the beating heart are feasible; they also identified refinements that are now being implemented for better control of lesion size and placement. [Work supported by NCI and NHLBI Grant 5R01 CA84588.]
Listening to a town: The urban soundscape as an image of the city
Authors: Semidor Catherine
Published: September 2013

City dwellers often have a visual representation of their town. They are able to identify some areas from pictures. But, urban sounds are also a characteristic part of the city’s identity. A previous paper [C. Semidor, Proceedings 20th PLEA, Santiago, Chile (2003)] shows the possibility to distinguish the soundscape of a ‘‘car-free’’ Sunday from the soundscape of a Sunday with cars. The proposed method based on the so-called soundwalk could be very illustrative for this suggestion. These soundwalks are sound recordings made with a ‘‘dummy’’ head and a DAT recorder, on walks following a trajectory with different urban forms and, in this case study, in different towns where a tramway is running. The acoustical images (time versus frequency graphs) of the sound signals could be a representation of these soundscapes. This type of information could help urban planners and other town designers to improve the acoustic comfort of the cities. The objective of this approach is to valorize what is pleasant and agreeable in the urban sound environment.
Transfer of knowledge from sound quality measurement to noise impact evaluation
Authors: Genuit Klaus
Published: September 2013

It is well known that the measurement and analysis of sound quality requires a complex procedure with consideration of the physical, psychoacoustical and psychological aspects of sound. Sound quality cannot be described only by a simple value based on A-weighted sound pressure level measurements. The A-weighted sound pressure level is sufficient to predict the probabilty that the human ear could be damaged by sound but the A-weighted level is not the correct descriptor for the annoyance of a complex sound situation given by several different sound events at different and especially moving positions (soundscape). On the one side, the consideration of the spectral distribution and the temporal pattern (psychoacoustics) is requested and, on the other side, the subjective attitude with respect to the sound situation, the expectation and experience of the people (psychology) have to be included in context with the complete noise impact evaluation. This paper describes applications of the newest methods of sound quality measurements—as it is well introduced at the car manufacturers—based on artifical head recordings and signal processing comparable to the human hearing used in noisy environments like community/traffic noise.
Using eccentricity in multilayered scatterer as mechanism for tunable phononic materials
Authors: Cai Liang-Wu
Published: September 2013

The concept of multiple scattering in single scatterers, originally proposed by the author, can be utilized to analyze the scattering of elastic waves by scatterers having multiple eccentric layers. Using a dual-layer circular eccentric cylindrical scatterer as an example, it is demonstrated that, in a certain frequency range, the geometric eccentricity can significantly influence the pattern of the scattered field. The geometric eccentricity of such a scatterer can be described by three parameters: the orientation angle between the line connecting the two centers and the incident direction; the ratio of radii of the two layers, and the ratio of the distance between two centers and the radius of the outer layer. It is found that, when the wavelength is comparable to the outer diameter of the scatterer, the pattern of the scattered wave field is extremely sensitive to all three geometric parameters. Furthermore, this is the frequency range that is very close to the band gap as dictated by the lattice structure. It is expected that when such multilayered scatterers are arranged in a lattice pattern, the eccentricity can be exploited for tuning the band-gap characteristics of the resulting phononic material.
Acousto–domain interaction in ferroelectric lithium niobate
Authors: Ostrovskii Igor V. , Borovoy Mukola M. , Korotchenkov Oleg O. , Nadtochii Andrij B. , Chupryna Roman G.
Published: September 2013

First observation of the reorientation of ferroelectric domains in the lithium niobate single crystals induced by ultrasound is reported. This effect is detected from the samples, which are treated by megahertz frequency-range ultrasound with above certain threshold amplitude at room temperature. Acoustic strain amplitude causing the domain reorientation is of the order of E10−5. The effect is directly revealed by chemically etched crystal surfaces, and independently confirmed by the acoustically induced evolution of x-ray diffraction rocking curves and changes in acousto-electric properties of the lithium niobate crystals. The physical mechanism responsible for the interaction of the domains and ultrasound can be attributed to the mechanical stress and piezoelectric field produced by a piezo-active acoustic wave. A new effect of acousto-domain interaction in ferroelectric crystals might be taken into account for a wide variety of fundamental physical phenomena involving propagation of the acoustic waves in real crystals.
Effects of frequency transposition on discrimination of recycled tonal sequences
Authors: Hashida Tomoko , Kayahara Takuro , Sato Takao
Published: September 2013

Recycled sequences have been used for examining perception of sequences which requires temporal-order judgments of components to eliminate advantages of the initial and the terminal components in sequence recognition. The purpose of this study was to examine whether listeners could discriminate recycled sequences when the center frequency was varied. Each stimulus in this study was a random sequence of ten 200-ms pure tones divided equally in log scale within 2/3 octave. The center frequency of the standard sequence was fixed at 500 Hz, while those of test sequences were varied from 62.5 to 4000 Hz. Two test sequences were prepared for each center frequency. One had the same order as the standard; the other had a different order by reversing two contiguous components. Subjects were asked to judge which one of these two test sequences had the same order as that of the standard sequence. Results indicated that (1) listeners could distinguish the order of sequences even when the center frequency was transposed, and that (2) the range of transposition within which listeners could distinguish was limited within several octaves.
Differentiating speech and nonspeech sounds via amplitude envelope cues
Authors: Lehnhoff Robert J. , Strange Winifred , Long Glenis
Published: September 2013

Recent evidence from neuroscience and behavioral speech science suggests that the temporal modulation pattern of the speech signal plays a distinctive role in speech perception. As a first step in exploring the nature of the perceptually relevant information in the temporal pattern of speech, this experiment examined whether speech versus nonspeech environmental sounds could be differentiated on the basis of their amplitude envelopes. Conversational speech was recorded from native speakers of six different languages (French, German, Hebrew, Hindi, Japanese, and Russian) along with samples of their English. Nonspeech sounds included animal vocalizations, water sounds, and other environmental sounds (e.g., thunder). The stimulus set included 30 2-s speech segments and 30 2-s nonspeech events. Frequency information was removed from all stimuli using a technique described by Dorman et al. [J. Acoust. Soc. Am. 102 (1997)]. Nine normal-hearing adult listeners participated in the experiment. Subjects decided whether each sound was (originally) speech or nonspeech and rated their confidence (7-point Likert scale). Overall, subjects differentiated speech from nonspeech very accurately (84% correct). Only 12 stimuli were not correctly categorized at greater than chance levels. Acoustical analysis is underway to determine what parameters of the amplitude envelope differentiate speech from nonspeech sounds.
The role of spectral asynchrony in the identification of spectrally smeared environmental sounds
Authors: Shafiro Valeriy , Gilichinskaya Yana
Published: September 2013

This study examined possible contributions of spectral asynchrony caused by the differences in filter group delays across channels to the previously reported decline in identification accuracy of several spectrally smeared environmental sounds [V. Shafiro, J. J. Jenkins, and W. Strange, J. Acoust. Soc. Am, 113(4), 2326–2327 (2003)]. As in the previous experiment, stimuli were obtained by processing environmental sounds through a noise-based vocoder with a varying number of frequency channels. In the present experiment, however, the group delays were held constant across channels, while the overall frequency response of the filters closely resembled the earlier one. Listeners were instructed to identify the most likely source of each sound by selecting it from 60 possible response options. Results indicated that identification accuracy improved for some environmental sounds, while it worsened for other sounds. Overall, there was little improvement in identification accuracy across channels. These findings are interpreted as reflecting the limitations in signal-processing parameters and undesirable processing artifacts. Preliminary results of a different signal-processing method that maintains a constant group delay and uses linear frequency intervals for individual channels indicate a greater improvement in identification accuracy.
The acquisition of voice onset time by English-learning infants
Authors: Lowenstein Joanna H. , Nittrouer Susan
Published: September 2013

Lisker and Abramson [Word 20, 384-422 (1964)] showed that voice onset time (VOT) for word-initial stops labeled as voiced and voiceless differ across languages, thus demonstrating that VOT is learned. Over the years, several studies have examined the developmental course of acquiring VOT for several languages, but questions remain regarding the time course of this development. Earlier studies of VOT acquisition have demonstrated that English learning infants initially produce stops with short-lag VOTs only, then go through a stage of ambiguous VOTs, finally developing two mature categories of voiced and voiceless. This study analyzed mean VOT and variability in word-initial stops produced in spontaneous samples by three infants, taped at approximately 2-month intervals between the ages of 12 months and 30 months. As predicted, these infants produced primarily voiced stops (VOT<40 ms) with moderate variability until approximately 21 months. Then longer lag stops began to appear and variability increased. Outliers (both voiced stops with extreme prevoicing and very long lag voiceless stops) were found. By the last recording session, all three infants showed mean voiced and voiceless VOTs approaching adult values, but still exhibited greater variability. [Work supported by NIDCD Grant No. DC-00633.]