bluuebunny/crossref_metadata_2025 huggingface dataset:
Teachers’ daily practices with curriculum materials: Toward a transactional view of the curriculum system
Authors: Raymond Kate M.
Published: November 2021

Recent research demonstrates that mathematics teachers rely on a variety of curriculum materials and must make meaning and synthesize these materials for use in a particular place with particular students. While there are multiple theories about the nature of this work and the factors which influence this work, the field continues to lack a theoretical basis with which to understand this multifaceted and complex work. This paper seeks to illuminate the process by which teachers come to make meaning from curriculum materials by the daily practices of one team of teachers. Findings supports a transactional view of curriculum in which students, teachers, curriculum materials, and contexts work with and on each other as curriculum emerges. Using this theory as a framework, multiple understandings of teachers’ work with curriculum can be synthesized as highlighting particular aspects of a larger curriculum system.
The feasibility of clinical evaluation for anterior uveitis through spectral‐domain optical coherence tomography in dogs
Authors: Jeong Youngseok , Kang Seonmi , Shim Jaeho , Lee Eunji , Jeong Dajeong , Park Sanghyun , Lee Songhui , Kim Su An , Seo Kangmoon
Published: November 2021

Objective

To evaluate the clinical application of spectral‐domain optical coherence tomography (SD‐OCT) for anterior uveitis in dogs.

Animals and procedures

Client‐owned dogs presenting with anterior uveitis and clinically healthy dogs were enrolled in this study. Included eyes were divided into 5 groups by flare grade and 3 groups by cell grade through slit‐lamp biomicroscopy. Each eye was examined using SD‐OCT following slit‐lamp biomicroscopy. The ratio of aqueous signal intensity to air signal intensity, which is called the aqueous‐to‐air relative intensity (ARI) index, was used to evaluate the flare grade. Cell number, central corneal thickness (CCT), and the presence of keratic precipitates (KPs) were analyzed on SD‐OCT. The OCT parameters, including ARI index, cell number, and CCT, were compared to the slit‐lamp clinical flare and cell grade.

Results

Thirty‐six eyes with anterior uveitis and 27 healthy eyes were enrolled. The ARI index showed a significant correlation with clinical flare grade (rs = 0.811, p < .001). In multiple regression analysis, the ARI index and CCT showed a significant negative correlation (r = −0.258, p = .044). The number of cells on SD‐OCT significantly increased with cell grade on slit‐lamp biomicroscopy (rs = 0.653, p < .001). The clinical flare grade and CCT were significantly correlated in the partial correlation analysis after controlling for age (partial correlation coefficient = 0.471, p = .002). KPs were observed in 61% of the eyes with flare using SD‐OCT (22/36 eyes).

Conclusions

Spectral‐domain optical coherence tomography could provide quantitative information, including the ARI index, cell counts, and CCT in dogs. SD‐OCT is an auxiliary modality for slit‐lamp biomicroscopy when evaluating anterior uveitis in dogs.
Functionally Graded Non-Periodic Cellular Structure Design and Optimization
Authors: Wang Jun , Huang Jida
Published: November 2021

Topological tailoring of materials at a micro-scale can achieve a diverse range of exotic physical and mechanical properties that are not usually found in nature. Modification of material properties through customizing the structural pattern paves an avenue for novel functional products design. This paper explores a non-periodic microstructure design framework for functional parts design with high-strength and lightweight. To address the geometric frustration problem commonly found in non-periodic microstructure designing, we employ a smooth transition layer to connect distinct structural patterns and thus achieve functional gradation among adjacent microstructures. The concept of spatial control points is introduced for the interpolation of this transition layer. To achieve a high-strength macro-structural performance for designing functional parts, we formulate the control points as the design variables and encapsulate them into a macro-structural design optimization problem. Given that our objective function involves expensive finite element (FE) simulations, a Bayesian optimization scheme is exploited to address the computational challenge brought by the FE simulation. Experimental results demonstrate that the proposed design framework can yield both functionally graded lightweight structures and high-strength macro-mechanical performance for the designing parts. The compatibility issue of non-periodic microstructure design is well-addressed. Comparative studies reveal that the proposed framework is robust and can achieve superior mechanical performance to design functional parts with spatially varying properties.
An Integrated Surrogate Modeling Method for Fusing Noisy and Noise-Free Data
Authors: Li Kunpeng , Wang Shuo , Liu Yin , Song Xueguan
Published: November 2021

Many datasets in engineering applications are heterogeneous mixtures of noise-free data, noisy data with known noise variances, and noisy data with unknown noise variances. This article proposes a data fusion method called the multi-type data fusion (MTDF) model, which fully utilizes the information provided by each of these types of data. To capture the underlying trend implied in the multiple types of data, the method approximately interpolates the noise-free data, while regressing the noisy data. The prediction accuracy of the MTDF model is compared with those of various surrogate models (interpolation models, regression models, and multi-fidelity models) on both numerical and practical engineering problems. In the experiments, the proposed MTDF model demonstrates higher performance than the other benchmark models. The effects of noise level and sample size of the noise-free data on the model performance are investigated, along with the robustness of the MTDF model. The results demonstrate the satisfactory feasibility, practicality, and stability of the MTDF.
Robust Topology Optimization of Graphene Platelets Reinforced Functionally Graded Materials Considering Hybrid Bounded Uncertainties
Authors: Cheng Jin , Lu Wei , Lou Yibin , Hu Weifei , Liu Zhenyu , Tan Jianrong
Published: November 2021

An efficient scheme for the robust topology optimization considering hybrid bounded uncertainties (RTOHBU) is proposed for the graphene platelets (GPLs) reinforced functionally graded materials (FGMs). By introducing the concept of the layer-wise FGMs, the properties of the GPLs reinforced FGMs are calculated based on the Halpin-Tsai micromechanics model. The practical boundedness of probabilistic variables is naturally ensured by utilizing a generalized Beta distribution in constructing the robust topology optimization model. To address the issue of lacking the information of critical loads in existing topology optimization approaches considering hybrid uncertainties, a gradient-attributed search is carried out at first based on the hypothesis of linear elasticity to determine the critical loads leading to the worst structural performance. Subsequently, the statistical characteristics of the objective structural performance under such critical loads are efficiently evaluated by integrating the univariate dimension reduction method and the Gauss–Laguerre quadrature, the accuracy of which is verified by the comparison analyses utilizing the results of Monte Carlo simulation as references. Furthermore, a novel realization vector set is constructed for the bounded probabilistic uncertainties to parallelize the sensitivity analysis and accelerate the optimization process. All the proposed innovations are integrated into the robust topology optimization scheme, the effectiveness and efficiency of which are verified by both numerical and realistic engineering examples.
Bubble Dynamics and Enhancement of Pool Boiling in Presence of an Idealized Porous Medium: A Numerical Study Using Lattice Boltzmann Method
Authors: Mondal Kaushik , Bhattacharya Anandaroop
Published: November 2021

This paper reports a single-component two-dimensional pseudo-potential phase change model using lattice Boltzmann method (LBM) to investigate the enhancement of pool boiling heat transfer inside an array of solid pillars with square cross section. The entire saturated pool boiling curve for the flat surface comprising different nucleate boiling regimes from boiling incipience (BI) to critical heat flux (CHF), transition boiling regime between CHF to Leidenfrost point (LP) and the film boiling regime has been obtained numerically. The effect of the array of solid pillars with square cross section has been quantitatively evaluated and expressed in the form of its corresponding boiling curve. It is found that the boiling incipience in the presence of solid array occurs at a lower surface superheat compared with that of a plane surface. Further, the solid array effectively delays the onset of film boiling. Qualitative analysis of pool boiling phenomenon shows the bubble dynamics in such solid structure including bubble nucleation, coalescence, growth, entrapment, splitting, and escape to be very different compared with a flat surface. Based on the heat flux values and trends, the entire boiling curve could be classified into four distinct zones. To the best of our knowledge, this is the first instance where LBM could predict the entire pool boiling curve for a porous medium. Finally, two different pillar arrays of porosity 90% and 98% are studied to examine the effect of porosity. It is found that the sensitivity of the heat transfer rates to porosity is significant especially at higher values of surface superheat.
Effect of Series and Parallel Combination of Photovoltaic Thermal Collectors on the Performances of Integrated Active Solar Still
Authors: Tiwari G. N. , Meraj Md. , Khan M. E. , Dwevedi V. K.
Published: November 2021

In this article, an analytical expression for hourly yield, electrical energy and overall exergy of self-sustained solar still integrated with series and parallel combination of photovoltaic thermal-compound parabolic concentrator (PVT-CPC) collectors have been derived. The analysis is based on the basic energy balance equation of the proposed active solar distillation system. Based on numerical computations, it has been observed that the yield is maximum for all self-sustained PVT-CPC collectors are connected in series (case (i)). Furthermore, the daily yield and exergy increase with the increase of water depth unlike passive solar still for all collectors connected in series. However, overall exergy decreases with an increase of water depth for all collectors connected in parallel (case (iv)). For numerical simulations, the total numbers of self-sustained PVT-CPC collectors has been considered as constant. Furthermore, an effect of series and parallel combination of PVT-CPC collectors on daily yield, electrical energy, and overall exergy has also been carried out. Following additional conclusions have also been drawn: (i) The daily yield of the proposed active solar still decreases with the increase of packing factor of semi-transparent photovoltaic (PV) module for a given water depth and electrical energy and overall exergy increase with water depth for case (i) as expected due to low operating temperature range at higher water depth in the basin. (ii) The daily yield, electrical energy, and overall exergy increase with the increase of water depth for all combination of series and parallel arrangement of PVT-CPC collectors for a packing factor of 0.22 as per our expectation.
Evaluation of Blast Simulation Methods for Modeling Blast Wave Interaction With Human Head
Authors: Sutar Sunil , Ganpule Shailesh
Published: November 2021

Blast-induced traumatic brain injury (bTBI) research is crucial in asymmetric warfare. The finite element analysis is an attractive option to simulate the blast wave interaction with the head. The popular blast simulation methods are ConWep-based pure Lagrangian, Arbitrary–Lagrangian–Eulerian, and coupling method. This study examines the accuracy and efficiency of ConWep and coupling methods in predicting the biomechanical response of the head. The simplified cylindrical, spherical surrogates and biofidelic human head models are subjected to field-relevant blast loads using these methods. The reflected overpressures at the surface and pressures inside the brain from the head models are qualitatively and quantitatively evaluated against the available experiments. Both methods capture the overall trends of experiments. Our results suggest that the accuracy of the ConWep method is mainly governed by the radius of curvature of the surrogate head. For the relatively smaller radius of curvature, such as cylindrical or spherical head surrogate, ConWep does not accurately capture decay of reflected blast overpressures and brain pressures. For the larger radius of curvature, such as the biofidelic human head, the predictions from ConWep match reasonably well with the experiment. For all the head surrogates considered, the reflected overpressure-time histories predicted by the coupling method match reasonably well with the experiment. Coupling method uniquely captures the shadowing and union of shock waves governed by the geometry-driven flow dynamics around the head. Overall, these findings will assist the bTBI modeling community to judiciously select an objective-driven modeling methodology.
Compact Thermosyphon Cooling System For High Heat Flux Servers: Validation Of Thermosyphon Simulation Code Considering New Test Data
Authors: Haynau Rémy , Marcinichen Jackson B. , Amalfi Raffaele L. , Cataldo Filippo , Thome John R.
Published: November 2021

Passive, gravity-driven thermosyphons represent a step-change in technology towards the goal of greatly reducing PUE (Power Usage Effectiveness) of datacenters by replacing energy hungry fans of air-cooling approach with a highly-reliable solution able to dissipate the rising heat loads demanded in a cost-effective manner. The European Union has launched a zero carbon-footprint target for datacenters by the timeline of 2030, which would include new standards for implementing green solutions. In the present study, a newly updated version of the general thermosyphon simulation code previously presented at InterPACK 2019 and InterPACK 2020 is considered. To facilitate the industrial transition to thermosyphon cooling technology, with its intrinsic complex flow phenomena, the availability of a general-use, widely validated design tool that handles both air-cooled and liquid-cooled types of thermosyphons is of paramount importance. The solver must be able to analyze and design thermosyphon-based cooling systems with high accuracy and handle the numerous geometric singularities in the working fluid’s flow path, besides that of the secondary coolant. Therefore, a new extensive validation of the thermosyphon simulation solver is performed and presented here versus experimental data gathered for a compact liquid-cooled thermosyphon design, which is being considered for the cooling of high-performance servers. The new experimental database has been gathered to be able to characterize the effect of filling ratio, heat load, secondary coolant temperature and mass flow rate on the cooling performance, using R1234ze(E) as a low GWP (Global Warming Potential) working fluid. This compact design has experimentally demonstrated high performance, maintaining the pseudo chip’s temperature lower than 45°C for evaporator footprint heat fluxes up to 18W/cm2. The comparison shows that the solver is able to accurately predict thermosyphon thermal-hydraulic performance, and based on this prediction, characterize the internal flow rate generated by the thermosyphon, which is key to correctly estimate the maximum heat removal capability.
Nonlocal Damage Modeling of Solder Joint Failure Under Thermomechanical Cyclic Loading
Authors: Maniar Youssef , Kabakchiev Alexander , Kuczynska Marta , Bazrafshan Masoomeh , Binkele Peter , Schmauder Siegfried
Published: November 2021

The increasing electrified mobility poses a challenge on reliability prediction of automotive electronics, especially when safety systems are concerned. The use of finite element simulation for accurate end-of-life prediction of automotive electronic devices under harsh environmental loading condition is getting increasingly significant. In particular, solder interconnection failure is in focus when subjected to thermomechanical loads. During cyclic loading, the initial deformation behavior and subsequent solder degradation can be modeled within finite element simulations using material damage coupled deformation models. Such models employ the calculation of an internal damage state variable at integration point level as functions of time, temperature and governing stress-strain state.

In this work, a thermodynamic consistent implicit nonlocal damage formulation is presented. This modeling approach allows absolute end-of-life prediction of different solder joint geometries under thermomechanical cyclic loading within finite element simulations. The presented nonlocal damage model consists of damage evolution with strain and stress state dependencies, such as stress multiaxiality. Furthermore, a numerical de-localization algorithm is proposed, in order to avoid instability of damage evolution caused by finite element mesh dependency. Finally, the advantages and implications of the nonlocal damage approach are discussed based on simulations of damage evolution in multiple solder joints of a QFN48 package under combined cyclic thermal and mechanical 4-point bending loading.
Characterization of High-Density Aircraft Electronic and Thermal Management Systems
Authors: Kasitz Joshua , Huitink David
Published: November 2021

As aircrafts move toward electrification with the research and development of hybrid-electric powertrains, the focus has begun to shift to the reliability challenges of electronic devices subject to flight. Electronic components in aircraft applications are subject to two main sources of failure inducing stresses: the thermomechanical stresses that develop due to unequal coefficients of thermal expansion of different materials used in the components, and the stresses developing due to shocks and vibrations during flight as well as landing and takeoff. While the challenge of dealing with CTE mismatches is applicable to electronic devices in general, the ambient conditions surrounding the aircraft in flight, combined with weight and space constrains add significant logistical issues to any cooling mechanism. This paper will focus on the environmental influence on the thermal dissipation profile that will ultimately lead to CTE failures. The push toward more-electric-aircraft (MEA) increases the need to further advance the power and versatility of electronic cooling systems to adequately manage high density power modules, which until recently were not highly incorporated in aviation systems. Environmental conditions will play a large role in the design space and limitations of potential cooling solutions and will dictate the effectiveness of current thermal management systems. In arising scenarios where high-density electronics cannot be contained within a pressurized and temperature-controlled cabin, drastic pressure and temperature swings, facilitated by the external environment, will lead to an extra source of fluctuating stress on the cooling system. This is likely to be a prevalent factor in hybrid-electric and all-electric powertrains as requiring environmental controlled spaces for major components could be limited. This can easily be seen in current attempts to examine and redesign local cooling systems for electric motors in aviation. Representing just one of the major cooling requirements on an electric aircraft, motor cooling systems demonstrate the universal cooling problems limiting all aspects of the powertrains system. This paper aims to define the impact of the changing environment, through a flight profile of an aircraft, on high density electronic cooling systems by assessing the potential system stressors that significantly impact performance, efficiency, and reliability of the cooling systems. It will also utilize local cooling efforts for motors to relate the general problems to applicable design considerations that must be understood to further the performance capability of the overall propulsion system.
Numerical Modeling of Continuous Dynamic Recrystallization in Sn-Based Solder Connection Under Cyclic Loading
Authors: Kuczynska Marta , Becker Ulrich , Maniar Youssef , Weihe Steffen
Published: November 2021

The reoccurring cyclic load imposed onto soldered electronic components during their operation time leads to accumulation of inelastic strains in the structure. On a microscale level, the degree of plastic deformation is determined by the formation and annihilation of dislocations, leading to continuous refinement by creation of new grain boundaries, precipitates relocation and growth. This microstructure rearrangement, triggered by an increasing amount of inelastic deformation, is defined as dynamic recrystallization.

This work presents a macroscale modelling approach for the description of continuous dynamic recrystallization observed in Sn-based solder connections. The model used in this work describes kinetics of macroscopic gradual evolution of equivalent grain size, where the initial grain size is continuously refined with increasing accumulated inelastic strain until a saturation grain size is reached. The rate and distribution of dynamic recrystallization is further numerically modelled dependent on the effective accumulated inelastic strain and governing stress multiaxiality. A parameter study of the presented model and its employment in finite element (FE) simulation is further described. Finally, FE simulation of the grain size evolution is demonstrated on an example of a bulky sample under isothermal cyclic mechanical loading, as well as a BGA-like structure under tensile, shear and mixed mode cyclic load.
Print-Consistency and Process-Interaction for Inkjet-Printed Copper on Flexible Substrate
Authors: Lall Pradeep , Goyal Kartik , Schulze Kyle , Hill Curtis
Published: November 2021

Printed electronics is a fastest growing and emerging technology that have shown much potential in several industries including automotive, wearables, healthcare, and aerospace. Its applications can be found not only in flexible but also in large area electronics. The technology provides an effective and convenient method to additively deposit conductive and insulating materials on any type of substrate. Comparing with traditional manufacturing processes, which involves chemical etching, this technology also comes to be relatively environmental friendly. Despite its status, it is not without its challenges. Starting from the material being compatible in the printer equipment to the point of achieving fine resolutions, and with excellent properties are some of the challenges that printed electronics face. Among the myriad of printing technologies such as Aerosol Jet, micro-dispensing, gravure printing, screen printing, Inkjet printing, Inkjet has gained much attention due to its low-cost, low material consumption, and roll-to-roll capability for mass manufacturing. The technology has been widely used in home and office, but recently gained interest in printed electronics in a research and development setting. Conductive materials used in Inkjet printing generally comprises of metal Nanoparticles that need to be thermally sintered for it to be conductive. The preferred metal of choice has been mostly silver due to its excellent electrical properties and ease in sintering. However, silver comes to be expensive than its counterpart copper. Since copper is prone to oxidation, much focus has been given towards photonic sintering that involves sudden burst of pulsed light at certain energy to sinter the copper Nanoparticles. With this technique, only the printed material gets sintered in a matter of seconds without having a great impact on its substrate, due to which it is also preferred in low temperature applications. With all the knowledge, there is still a large gap in the process side with copper where it is important to look how the print process affects the resolution of the print along with the effect of post-print processes on electrical and mechanical properties. In this paper, a copper Inkjet ink is utilized for understanding the effect of Inkjet print parameters on the ejected droplet and its resolution. Post-print process is also quantified using a photonic sintering equipment for excellent electrical and mechanical properties. To demonstrate the complete process, commercial-off-the-shelf components will also be mounted on the additively printed pads via Inkjet. Statistically, control charting technique will be utilized to understand the capability of the Inkjet process.
Development of Multi-Layer Circuitry Using Electrically Conductive Adhesive and Low-Temperature Solder Material for Surface-Mount Component Attachment
Authors: Lall Pradeep , Narangaparambil Jinesh , Miller Scott
Published: November 2021

The increased versatility in the design and manufacturing of components in low volumes, as well as the shorter time between design and prototype, has increased interest in the field of additively printed electronics. The ability to directly print on a variety of substrates, whether rigid, flexible, or conformable, provides several benefits over conventional electronics fabrication methods. Furthermore, the growing complexity of flexible electronics necessitates the development of multilayered circuits similar to traditional PCBs to decrease the volumetric and gravimetric effect of the underlying electronics. Using z-axis interconnections with dielectric materials, which may allow or prevent the connection between two layers, is one method of reaching several layers of circuits. In this paper, a working multilayer circuitry test vehicle is designed and additively printed using the direct-write method. The circuit model involves conductive and dielectric ink printing, as well as passive and active component attachments using an electrically conductive adhesive (ECA) and low-temperature solder (LTS). The study also shows details about the process of developing dielectric printing parameters for microvias for multilayer z-axis interconnections.
Effect of Lamination Parameters and Mechanical Folding on SOH Degradation of Li-ion Battery Subjected to Accelerated Life Testing
Authors: Lall Pradeep , Soni Ved , Narangaparambil Jinesh , Miller Scott
Published: November 2021

The growing interest in the flexible field of electronics has provided impetus to incorporation of electronic components such as resistors, capacitors, LEDs, sensors, etc. into flexible circuits. Power sources are another significant component of a majority of electronic circuits which need to be integrated in flexible circuits so as to push the bounds of the wearable technology. One way to do this is by using a laminated film to laminate ultra-thin pouch batteries and then bind them to a flexible substrate. During the lamination process, these batteries are exposed to higher temperatures (above 100 °C), albeit for a short period of time, which can result in damage to the battery’s internals. In this study, a Li-ion pouch cell has been laminated using a hot roller lamination process with different conditions of lamination speed and temperature. The laminated batteries have then been subjected to accelerated life testing in presence and absence of static and dynamic mechanical folding so as to investigate the effect of folding on the laminated batteries. Further, the SOH degradation of the tested batteries is computed and has been incorporated in a regression model so as to study the effect of lamination parameters.
Assessment of nonreleasing antifungal surface coatings bearing covalently attached pharmaceuticals
Authors: Naderi Javad , Griesser Hans J. , Coad Bryan R.
Published: November 2021

There are many reports of antimicrobial coatings bearing immobilized active agents on surfaces; however, strong analytical evidence is required to verify that the agents are indeed covalently attached to the surface. In the absence of such evidence, antimicrobial activity could result from a release of active agents. We report a detailed assessment of antifungal surface coatings prepared using covalent attachment chemistries, with the aim of establishing a set of instrumental and biological evidence required to convincingly demonstrate antimicrobial activity due to nonreleasing, surface active compounds and to exclude the alternate possibility of activity due to release. The strongest biological evidence initially supporting permanent antifungal activity was the demonstration of the ability to reuse samples in multiple, sequential pathogen challenges. However, additional supporting evidence from washing studies and instrumental analysis is also required to probe the possibility of gradual desorption of strongly physisorbed compounds versus covalently attached compounds. Potent antifungal surface coatings were prepared from approved pharmaceutical compounds from the echinocandin drug class (caspofungin, anidulafungin, and micafungin) and assessed by microbiological tests and instrumental methods. Carbonyl diimidazole linking chemistry enabled covalent attachment of caspofungin, anidulafungin, and micafungin to plasma polymer surfaces, with antifungal surface activity likely caused by molecular orientations that present the lipophilic tail toward interfacing fungal cells. This study demonstrates the instrumental and biological evidence required to convincingly ascertain activity due to nonreleasing, surface active compounds and summarize these as three criteria for assessing other reports on surface-immobilized antimicrobial compounds.
ACOUSTICAL SOCIETY OF AMERICA PIONEERS OF UNDERWATER ACOUSTICS MEDAL 2021: Finn Jensen
Authors: Jensen Finn
Published: November 2021

The Pioneers of Underwater Acoustics Medal is presented to an individual irrespective of nationality, age, or society affi liation, who has made an outstanding contribution to the science of underwater acoustics, as evidenced by publication of research in professional journals or by other accomplishments in the fi eld. The award was named in honor of fi ve pioneers in the fi eld: H. J. W. Fay, R. A. Fessenden. H. C. Hayes, G. W. Pierce, and P. Langevin.
Characterization of open woodwind toneholes by the tube reversed method
Authors: Garcia Mayén H. , Kergomard J. , Vergez C. , Guillemain P. , Jousserand M. , Pachebat M. , Sanchez P.
Published: November 2021

Woodwind tonehole's linear behavior is characterized by two complex quantities: the series and shunt acoustic impedances. A method to determine experimentally these two quantities is presented for the case of open toneholes. It is based on two input impedance measurements. The method can be applied to clarinet-like instruments, and can be used for undercut toneholes as well as toneholes with pads above their output, under the condition that a symmetry axis exists. The robustness of the method proposed is explored numerically through the simulation of the experiment when considering geometrical and measurement uncertainties. Experimental results confirm the relevance of the method proposed to estimate the shunt impedance. Even the effect of small changes in the hole's geometry, such as those induced by undercutting, are characterized experimentally. The main effect of undercutting is shown to be a decrease in the tonehole's acoustic mass, in agreement with theoretical considerations based on the shape of the tonehole. Investigation on the effects of pads will be studied in a further work. Experimental results also reveal that losses in toneholes are significantly higher than those predicted by the theory. Therefore, the method is suitable for the experimental determination of the shunt impedance, but it is not convenient for the characterization of the series impedance.
Sensitivity of mixed layer duct propagation to deterministic ocean features: The interaction parameter
Authors: Colosi John A. , Zinicola-Lapin William
Published: November 2021

Surface duct propagation can be affected by deterministic ocean features such as fronts, eddies, filaments, and/or density compensated temperature and salinity anomalies (spice). Using the concept of duct modal structure and the Dyson series solution to the wave equation, we present a non-dimensional parameter Γmn, termed the interaction parameter, that quantifies the strength of mode coupling between a surface duct mode m and any other mode n as a function of ocean feature scales and acoustic frequency. Weak, first order coupling is given by Γmn < 1 where as strong, higher order coupling has Γmn > 1. Importantly, there is a frequency dependent resonance condition associated with the range width of the perturbations, Δ, such that Γmn goes to zero as Δ approaches 0 and infinite. The utility of the interaction parameter in estimating the stability of mixed layer propagation is demonstrated using numerical examples of a cold eddy and of a hot and salty spice feature.
The impact of internal tides and gravity waves on key acoustic parameters and acoustic transmission loss near the Amazon shelf
Authors: Schönau Martha , Coelho Emanuel , Helber Robert , Shriver Jay , Verlinden Kathryn
Published: November 2021

Upper ocean variability depends on tides and wind forcing. The barotropic tide creates baroclinic internal tides and internal gravity waves (IGWs) that can propagate long distances and dissipate, impacting mixed layer and thermocline depths, vertical thermal gradients, and mixing. In the last decade, there has been an effort to include tidal motions in global HYCOM (HYbrid Coordinate Ocean Model). Here, we look at the impacts of tidally driven motions on acoustic propagation along the Amazon shelf by comparing acoustic transmission loss and key acoustic parameters in 1/25 deg Global HYCOM model runs with and without tides. Acoustic runs were performed at mid-frequencies using Bellhop3D at depths above and below the sonic-layer depth (SLD). Key acoustic parameters assessed include the SLD and vertical sound-speed gradients. Although the impacts of the internal waves and tides on acoustics are intermingled with the effects of other stochastic ocean processes (e.g., mesoscale eddies, fronts, and atmospheric forcing), timeseries analysis indicates that there is acoustic sensitivity to tidally forced variability. These ocean-acoustic results can be used for future development of machine learning algorithms to model coupled oceanographic and acoustical processes.
Relationship between salinity of the liquid and shell composition on the resonance frequency of the C3F8 lipid coated microbubbles
Authors: Jafarisojahrood Amin , Yang Celina , Counil Claire , Nittayacharn Pinuta , deLeon A. l. C. , Exner Agata , Goertz David , Kolios Michael
Published: November 2021

Lipid-coated microbubbles (MBs) are used in contrast-enhanced ultrasound (CEUS) imaging and MB enhanced therapeutic ultrasound (US). Understanding the MB behavior and the influence of the surrounding medium on its response to the US is necessary to select the suitable US exposure parameters. The MB lipid coating is often charged, however the influence of the ions in the medium on MB behavior is not fully understood. In this work, the influence of the medium salinity on the pressure-dependent MB behavior is investigated for the first time. MBs of different lipid shell compositions are size isolated to achieve the same size distribution. The MBs linear and pressure-dependent attenuation are measured in deionized water, PBS 1×, PBS 2×, and PBS 10× using a system of aligned PVDF 100% bandwidth transducers with a center frequency of 10 MHz and exposures with peak to peak pressure range of 3–140 kPa. With increasing salinity, the linear resonance frequency decreases up to 50% for conventional lipid shell compositions, and the pressure dependence of the resonance frequency is inhibited. By modifying the shell PEG ratio, the salinity effects can significantly be altered. Moreover, the nonlinear pressure-dependent resonance frequency is restored with applications to increased CEUS.
Cavitation dynamics of histotripsy bubble cloud nucleated from echogenic liposomes
Authors: Bhargava Aarushi , Huang Shaoling , McPherson David D. , Bader Kenneth B.
Published: November 2021

Deep vein thrombosis is a serious health concern worldwide. Administration of catheter-directed thrombolytics is the primary approach to achieve vessel patency for critical obstructions. Adjuvant techniques that localize thrombolytic delivery will improve treatment outcomes and reduce the potential caustic bleeding associated with systemic lytic administration. Histotripsy is a bubble-based focused ultrasound therapy that has been shown to act synergistically with lytic to promote clot degradation. Combining histotripsy with a targeted drug delivery agent may further improve treatment efficacy. Echogenic liposomes are vesicles formulated to entrain the thrombolytic, and can be triggered with ultrasound to release drugs locally. The objective of this study was to assess histotripsy bubble cloud dynamics nucleated from echogenic liposomes in an in vitro venous flow model. The change in liposome echogenicity following histotripsy exposure was assessed with high frame rate imaging. Hypoechogenicity indicative of liposome destruction extended beyond the focal region, with a strong decrease in pixel intensity immediately after the applied histotripsy pulse. Interestingly, echogenicity was restored to baseline levels over the course of ∼4 s, which was attributed to vigorous fluid mixing from bubble cloud oscillations. These results indicate an interesting range of bubble cloud behaviors when histotripsy is combined with echogenic liposomes.
Static magnetic fields dampen focused ultrasound-induced cavitation and blood-brain barrier opening outcome
Authors: Yang Yaoheng , Pacia Christopher P. , Ye Dezhuang , Yue Yimei , Chien Chih-Yen , Chen Hong
Published: November 2021

MRI-guided focused ultrasound combined with microbubbles has been used in clinical studies for blood-brain barrier (BBB) opening. However, the impact of the static magnetic field generated by an MRI scanner on the BBB opening outcome has not been evaluated. The objective of this study was to determine the relationship of the static magnetic field of an MRI scanner on focused ultrasound combined with microbubble-induced BBB opening. Mice were divided into four groups which were sonicated by FUS in different static magnetic fields B0 (∼0T, 1.5T, 3.0T, and 4.7T) with all other experimental parameters kept the same. Microbubble cavitation activity was monitored by passive cavitation detection during FUS after microbubble injection. After sonication, contrast-enhanced T1-weighted MRI and Evans blue were used to evaluate the BBBO outcome. The microbubble cavitation dose decreased by an average of 2.1 dB at 1.5T (P = 0.05), 2.9 dB at 3.0T (Pi = 0.01), and 3.0 dB at 4.7T (P = 0.01) compared with that outside the magnetic field. It also decreased Evans blue trans-BBB delivery 1.4-fold at1.5T (P = 0.009), 1.6-fold at 3.0T (P < 0.001), and 1.9-fold at 4.7T (P < 0.001). These findings demonstrated that static magnetic fields dampened microbubble cavitation and decreased trans-BBB delivery by FUS.
Atomization of a collagenase-treated tendon
Authors: Smallcomb Molly , Simon Julianna
Published: November 2021

Microfountains and atomization have been observed at tissue-air interfaces with focused ultrasound (fUS) and cause surface erosion. Highly collagenous tissues, such as tendon, have been resistant to erosion from atomization. Here, we evaluate whether tendon erosion is achievable after pre-treatment with collagenase, an enzyme that breaks down collagen. Fresh bovine tendons were cut lengthwise and submerged in 0.1% w/v collagenase solution for up to 24 h. Then, the tendon was partially submerged in water and the tendon-air interface insonified with 1.5 MHz fUS pulses of 10–20 ms at 1 Hz and predicted peak pressures of p+ = 106 MPa (p- = 28 MPa) for up to 5 min. The microfountain and atomization was monitored with high-speed photography. Results showed microfountains formed in collagenase-treated tendons with maximum heights reaching 4 mm; no fountains were observed in unaltered tendons. Additionally, surface erosion was observed upon gross examination in the collagenase-treated tendons. For 2-min treatments, 10 ms pulses produced ∼24 mm diameter holes while 20 ms pulses produced ∼34 mm holes but showed some thermal injury. No tissue erosion was observed in the unaltered tendons. These results suggest erosion may be achievable in collagen-degraded tendons such as tendinosis. [Work supported by NSF-GRFP-DGE1255832 and NIH-NIBIB-EB027886.]
Fully acoustic NDT for composite plate via LDR technique
Authors: Hanuman Nudurupati S. , Bose Tanmoy
Published: November 2021

The contact-based NDT methods occupy the industrial application to evaluate the material integrity. But, some difficulties are faced during inspection of the structures due to vast impedance mismatch at boundary and highly elevated temperatures. It is a big challenge to the modern NDT field. The noncontact NDT methods have overcome these challenges. Meanwhile, nonlinear techniques have been growing in advance to evaluate micro-scale damages. This study presents that air-coupled acoustic testing based on the local defect resonance (LDR) technique. In order, the numerical and experimental study has been carried out on a composite plate. Theexplicit dynamic analysis is carried out for numerical study using the ABAQUS software package. The dual piezo-speakers and microphones are used in an experimental case. The chirp signals are provided to the plate to stipulate the damage in both numerical and experimental cases. Corresponding sound pressure levels (SPL) are obtained at the damage region in numerical and experimental cases. The output data are processed by using MATLAB in an experimental case to get sound pressure levels (SPL).
Production and perception of English phonemes for Chinese college students
Authors: Liu Chang , Wan Yunzi , Liu Junbo , Tao Sha , Wang Wenjing
Published: November 2021

The production and perception of English vowels and consonants were measured for Chinese college students who started their English education from 9 to 13 years old. In the production experiment, 12 English vowels were recorded in the /hVd/ context and twenty one English consonants were recorded in /aCa/ context for each participant. In the perception experiment, participants were asked to identify English vowels in /hVd/ and English consonants in /aCa/ that were produced by a young female American English native speaker. In both production and perception, vowels were markedly more challenging than consonants with vowel production and perception scores around 60% and consonant production and perception approximately 90%. Moreover, there was a significant correlation between consonant production and perception, but not between vowel production and perception. These results indicate that Chinse college students’ main difficulty in English phonetic production and perception are vowels rather than consonants at simple phonetic contexts like /VCV/ and /CVC/ structures. The second language learning models will be discussed to interpret these findings. [Work supported by the Open Project Fund from the National Key Laboratory of Cognitive Neuroscience and Learning at Beijing Normal University, China, and University of Texas at Austin Research Grant.]
Perception and imitation of prevoicing across language backgrounds
Authors: Clare Emily J. , Schertz Jessamyn
Published: November 2021

The present study investigates speakers’ ability to perceive and imitate prevoicing, testing speakers of languages differing its contrastive status: those where prevoicing serves as a primary cue to the laryngeal contrast (Indo-Aryan languages; “true voicing” languages, e.g., Tagalog), those where prevoicing never occurs (“aspirating” languages, e.g., Cantonese), and those where prevoicing occurs in free variation (other aspirating languages, e.g., English). After hearing pairs of Hindi words differing in presence/absence of prevoicing, participants were asked to imitate them, followed by an ABX discrimination task. Preliminary findings show above-chance discrimination accuracy as well as significant imitation of the difference in participants all language backgrounds, with place of articulation, consonantal, and vocalic cues all affecting the extent of prevoicing in production. As expected, speakers of languages where prevoicing is absent showed less overall prevoicing than other groups; however, there were not clear differences across language groups in discrimination ability. While faithful imitation was usually associated with accurate discrimination, good discrimination was also found on many tokens that were not faithfully imitated, indicating that other (production-based) factors are necessary to account for variability in imitative ability.
Language dominance affects auditory translation priming in heritage speakers
Authors: Soo Rachel , Monahan Philip J.
Published: November 2021

Late L2 learners show translation priming from the first language to the second (L1–L2), while L2–L1 effects are inconsistent (Altarriba & Basnight-Brown, 2007). Typically, late L2 learners are both less dominant in the L2 and have a later L2 age of acquisition, making the relative contribution of language dominance and age of acquisition in L2–L1 priming unclear. We test Cantonese heritage and native speakers in an auditory translation priming paradigm. As heritage speakers first learn Cantonese (L1) but later become more proficient in English (L2), this profile potentially allows for the dissociation of dominance and age of acquisition in translation priming. If age of acquisition is the primary factor, more priming is expected to occur in the L1–L2 (Cantonese-English) direction; however, if dominance plays a stronger role, priming is expected to occur in the L2–L1 (English-Cantonese) direction. Preliminary results indicate that native speakers show L1–L2 but not L2–L1 priming, consistent with previous findings, while heritage speakers show priming in both directions, but stronger L2–L1 priming. The inter-condition difference is greater for native speakers. In short, age of acquisition plays a role in bilingual language processing (Silverburg & Samuel, 2004) and potentially drives auditory translation priming effects more strongly than language dominance.
Real-time visual acoustic feedback in computer-assisted pronunciation training
Authors: Rehman Ivana
Published: November 2021

Previous research on visualization of speech segments for pronunciation training suggests that such learning results in improved segmental production (e.g., Katrushina et al., 2015; Olson, 2014; Patten & Edmonds, 2015). However, investigation into real-time formant visualization for L2 vowel production training has been limited to either training a single or a pair of vowels (Carey, 2004; Sakai, 2016) and to examination of improvement on trained items only (Katrushina et al., 2015). This project investigates the effects of real-time formant visualization on production training for eight L2 vowels in trained and untrained environments as well as spontaneous speech. L2 learners (n = 11) participated in nine 30-minute training sessions, during which they used a formant visualization system to practice their vowel production. A control group (n = 8) was involved in audio-only vowel production training. Pre-test, post-test, and delayed post-test design was used, and pronunciation improvement was analyzed acoustically using Mahalanobis distance and mixed-effects modeling. The use of real-time visual acoustic feedback resulted in retained improvement in vowel quality in both trained and untrained items than audio-only training. Spontaneous speech was not improved. The findings suggest that this system could be used as an effective pedagogical tool for L2 learners.